Large accumulation of micro-sized synthetic polymer particles in the sea surface microlayer.

PubMed

Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Kang, Jung-Hoon; Kwon, Oh Youn; Han, Gi Myung; Shim, Won Joon

2014-08-19

Determining the exact abundance of microplastics on the sea surface can be susceptible to the sampling method used. The sea surface microlayer (SML) can accumulate light plastic particles, but this has not yet been sampled. The abundance of microplastics in the SML was evaluated off the southern coast of Korea. The SML sampling method was then compared to bulk surface water filtering, a hand net (50 μm mesh), and a Manta trawl net (330 μm mesh). The mean abundances were in the order of SML water > hand net > bulk water > Manta trawl net. Fourier transform infrared spectroscopy (FTIR) identified that alkyds and poly(acrylate/styrene) accounted for 81 and 11%, respectively, of the total polymer content of the SML samples. These polymers originated from paints and the fiber-reinforced plastic (FRP) matrix used on ships. Synthetic polymers from ship coatings should be considered to be a source of microplastics. Selecting a suitable sampling method is crucial for evaluating microplastic pollution.

Submonolayer Quantum Dot Infrared Photodetector

NASA Technical Reports Server (NTRS)

Ting, David Z.; Bandara, Sumith V.; Gunapala, Sarath D.; Chang, Yia-Chang

2010-01-01

A method has been developed for inserting submonolayer (SML) quantum dots (QDs) or SML QD stacks, instead of conventional Stranski-Krastanov (S-K) QDs, into the active region of intersubband photodetectors. A typical configuration would be InAs SML QDs embedded in thin layers of GaAs, surrounded by AlGaAs barriers. Here, the GaAs and the AlGaAs have nearly the same lattice constant, while InAs has a larger lattice constant. In QD infrared photodetector, the important quantization directions are in the plane perpendicular to the normal incidence radiation. In-plane quantization is what enables the absorption of normal incidence radiation. The height of the S-K QD controls the positions of the quantized energy levels, but is not critically important to the desired normal incidence absorption properties. The SML QD or SML QD stack configurations give more control of the structure grown, retains normal incidence absorption properties, and decreases the strain build-up to allow thicker active layers for higher quantum efficiency.

Salmeterol versus slow-release theophylline combined with ketotifen in nocturnal asthma: a multicentre trial. French Multicentre Study Group.

PubMed

Muir, J F; Bertin, L; Georges, D

1992-11-01

We wished to assess the efficacy of inhaled salmeterol (SML; 50 micrograms b.i.d.) compared to a combination of slow-release theophylline and ketotifen p.o. (TK; T 300 mg+K 1 mg b.i.d.) for the treatment of nocturnal asthma. Ninety six patients with nocturnal asthma, (forced expiratory volume in one second (FEV1) 60-90% of predicted value, reversibility > or = 15%, at least two nocturnal awakenings per week) were eligible for a multicentre, double-blind, double-dummy cross-over study (14-day run-in, two successive 28-day treatment periods). Efficacy was assessed as success/failure, success being defined as the complete disappearance of nocturnal symptoms/awakening during the last week of each treatment period. There was a statistically significant difference between SML and TK for this criterion: 46% and 39% success with SML during periods I (first 28-day period) and II (following the cross-over), compared to only 15% and 26% with TK, respectively (p < 0.01). SML was also significantly better for the other criteria (lung function, rescue salbutamol intake during day and night). Side-effects were five times less frequent in SML-treated patients (p < 0.004). Efficacy and tolerance of SML were obviously far better than those of TK in patients with nocturnal asthma.

Fixation and detachment of superior and anterior malleolar ligaments in human middle ear: Experiment and modeling

PubMed Central

Dai, Chenkai; Cheng, Tao; Wood, Mark W.; Gan, Rong Z.

2007-01-01

The aim of this study is to investigate the function of the superior malleolar ligament (SML) and the anterior malleolar ligament (AML) in human middle ear for sound transmission through simulations of fixation and detachment of these ligaments in human temporal bones and a finite element (FE) ear model. Two laser vibrometers were used to measure the vibrations of the tympanic membrane (TM) and stapes footplate. A 3-D FE ear model was used to predict the transfer function of the middle ear with ligament fixation and detachment. The results demonstrate that fixations and detachments of the SML and AML had different effects on TM and stapes footplate movements. Fixation of the SML resulted in a reduction of displacement of the TM (umbo) and the footplate at low frequencies (f < 1000 Hz), but also caused a shift of displacement peak to higher frequencies. Fixation of both SML and AML caused a reduction of 15 dB at umbo or stapes at low frequencies. Detachment of the SML had almost no effect on TM and footplate mobility, but AML detachment had a minor effect on TM and footplate movement. The FE model was able to predict the effects of SML and AML fixation and detachment. PMID:17517484

Scharioth Macula Lens: A new intraocular implant for low-vision patients with stabilized maculopathy- first experience.

PubMed

Nekolova, Jana; Rozsival, Pavel; Sin, Martin; Jiraskova, Nada

2017-06-01

To present the initial results of Scharioth Macula Lens (SML) implantation. The SML is a new add-on intraocular lens designed to increase uncorrected near visual acuity (UCVA) in patients with stabilized maculopathy. Eight patients were included in the study. All met the indication criteria before SML implantation. An SML was implanted in the better seeing eye. Near and distance visual acuity were tested. Possible complications and patient complaints were recorded and patients were asked about their quality of vision after SML implantation. The examination was carried out on day 1, 1 week, 1, 3 and 6 months after surgery. Six-month-results are presented. Apart from one, all patients with the SML had good near visual acuity at a recommended reading distance of 15 cm. Preoperatively, the mean (min-max) near UCVA was J13 (J8-J16), mean distance BCVA was 0.27. Postoperatively, the best results were after 1 month - near UCVA was J2.5 (J1-J7), distance BCVA was 0.26. Three months after surgery, this decreased to J4.5 (J1-J8); distance VA remained 0.25. Six months postoperatively - near vision was J4 (J1-J8) and distance VA was unchanged. Patients reported problems with reading speed and reading distance. Daily exercise improved their reading ability. One patient converted to wet AMD 3 months post-implantation. The SML is a new hope for low-vision patients. It acts as a magnifier in the eye. It is a suitable method for increasing near visual acuity in patients with inactive maculopathy.

Turbulent Mixing and Vertical Heat Transfer in the Surface Mixed Layer of the Arctic Ocean: Implication of a Cross-Pycnocline High-Temperature Anomaly

NASA Astrophysics Data System (ADS)

Kawaguchi, Yusuke; Takeda, Hiroki

2017-04-01

This study focuses on the mixing processes in the vicinity of surface mixed layer (SML) of the Arctic Ocean. Turbulence activity and vertical heat transfer are quantitatively characterized in the Northwind Abyssal Plain, based on the RV Mirai Arctic cruise, during the transition from late summer to early winter 2014. During the cruise, noticeable storm events were observed, which came over the ship's location and contributed to the deepening of the SML. According to the ship-based microstructure observation, within the SML, the strong wind events produced enhanced dissipation rates of turbulent kinetic energy in the order of magnitude of ɛ = 10-6-10-4W kg-1. On thermal variance dissipation rate, χ increases toward the base of SML, reaching O(10-7) K2 s-1, resulting in vertical heat flux of O(10) W m-2. During the occasional energetic mixing events, the near-surface warm water was transferred downward and penetrated through the SML base, creating a cross-pycnocline high-temperature anomaly (CPHTA) at approximately 20-30 m depth. Near CPHTA, the vertical heat flux was anomalously magnified to O(10-100) W m-2. Following the fixed-point observation, in the regions of marginal and thick ice zones, the SML heat content was monitored using an autonomous drifting buoy, UpTempO. During most of the ice-covered period, the ocean-to-ice turbulent heat flux was dominant, rather than the diapycnal heat transfer across the SML bottom interface.

Impacts of temperature increase and acidification on thickness of the surface mucopolysaccharide layer of the Caribbean coral Diploria spp.

NASA Astrophysics Data System (ADS)

Pratte, Zoe A.; Richardson, Laurie L.

2014-06-01

Coral mechanisms of resilience and resistance to stressors such as increasing sea surface temperature and ocean acidification must first be understood in order to facilitate the survival of coral reefs as we know them. One such mechanism is production of the protective surface mucopolysaccharide layer (SML). In this study, we investigated changes in the thickness of the SML in response to increasing temperature and acidification for the three Caribbean scleractinian coral species of the genus Diploria, which have been shown to exhibit differential resilience to disease and bleaching. Among the three species, Diploria strigosa is known to have a higher susceptibility to disease, Diploria labyrinthiformis is known to bleach more quickly, and Diploria clivosa is relatively unstudied. When temperature was increased from 25 to 31 °C over a 1- or 6-week period, the overall thickness of the SML decreased from 33 to 55 % for all three species. Average SML thickness at 25 °C for all three species ranged from 106 to 156 μm, while average thickness at 31 °C ranged from 64 to 86 μm. SML thickness was significantly different among species at 25 °C, but not at 31 °C. D. labyrinthiformis demonstrated lower fragment mortality due to thermal stress when compared to the other Diploria species. Acidification from pH 8.2 to 7.7 over 5 weeks had no effect on SML thickness for any species. The observed decrease in SML thickness in response to increased temperature might be attributed to a decrease in the production of mucus or an increase in the viscosity of the SML. These findings may help to explain the increased prevalence of coral disease during the warmer months, since increased temperature compromises an important aspect of coral innate immunity, as well as differences in disease and bleaching susceptibilities between Diploria species.

Design and fabrication of a hybrid maglev model employing PML and SML

NASA Astrophysics Data System (ADS)

Sun, R. X.; Zheng, J.; Zhan, L. J.; Huang, S. Y.; Li, H. T.; Deng, Z. G.

2017-10-01

A hybrid maglev model combining permanent magnet levitation (PML) and superconducting magnetic levitation (SML) was designed and fabricated to explore a heavy-load levitation system advancing in passive stability and simple structure. In this system, the PML was designed to levitate the load, and the SML was introduced to guarantee the stability. In order to realize different working gaps of the two maglev components, linear bearings were applied to connect the PML layer (for load) and the SML layer (for stability) of the hybrid maglev model. Experimental results indicate that the hybrid maglev model possesses excellent advantages of heavy-load ability and passive stability at the same time. This work presents a possible way to realize a heavy-load passive maglev concept.

Preparation and Evaluation of Surface Modified Lactose Particles for Improved Performance of Fluticasone Propionate Dry Powder Inhaler.

PubMed

Singh, Deepak J; Jain, Rajesh R; Soni, P S; Abdul, Samad; Darshana, Hegde; Gaikwad, Rajiv V; Menon, Mala D

2015-08-01

Dry powder inhalers (DPI) are generally formulated by mixing micronized drug particles with coarse lactose carrier particles to assist powder handling during the manufacturing and powder aerosol delivery during patient use. In the present study, surface modified lactose (SML) particles were produced using force control agents, and their in vitro performance on dry powder inhaler (DPI) formulation of Fluticasone propionate was studied. With a view to reduce surface passivation of high surface free energy sites on the most commonly used DPI carrier, α- lactose monohydrate, effects of various force control agents such as Pluronic F-68, Cremophor RH 40, glyceryl monostearate, polyethylene glycol 6000, magnesium stearate, and soya lecithin were studied. DPI formulations prepared with SML showed improved flow properties, and atomic force microscopy (AFM) studies revealed decrease in surface roughness. The DSC and X-ray diffraction patterns of SML showed no change in the crystal structure and thermal behavior under the experimental conditions. The fine particle fraction (FPF) values of lactose modified with Pluronic F-68, Cremophor RH 40, glyceryl monostearate were improved, with increase in concentration up to 0.5%. Soya lecithin and PEG 6000 modified lactose showed decrease in FPF value with increase in concentration. Increase in FPF value was observed with increasing concentration of magnesium stearate. Two different DPI devices, Rotahaler(®) and Diskhaler(®), were compared to evaluate the performance of SML formulations. FPF value of all SML formulations were higher using both devices as compared to the same formulations prepared using untreated lactose. One month stability of SML formulations at 40°C/75% RH, in permeable polystyrene tubes did not reveal any significant changes in FPF values. SML particles can help in reducing product development hindrances and improve inhalational properties of DPI.

Natural Surfactant Enrichments in the Atlantic Ocean Between 50°N and 50°S: Data from the Atlantic Meridional Transect, Oct-Nov 2014

NASA Astrophysics Data System (ADS)

Sabbaghzadeh, B.; Upstill-Goddard, R. C.; Nightingale, P. D.; Beale, R.

2016-02-01

Surfactants that decrease air-sea gas exchange by suppressing the gas transfer velocity (kw) show variable enrichments in the sea surface microlayer (SML) relative to the underlying water. This reflects variability in the rates of surfactant production and consumption. Total surfactant activity (SA: equivalent to Triton-X-100, mgL -1) was determined daily between the UK and the Falkland Islands, during cruise 24 of the Atlantic Meridional Transect programme (AMT 24). Samples were simultaneously obtained from the SML (Garrett screen), from the ship's underway system (inlet at 7m) and in hydrocasts to 500m. SA analysis was by hanging mercury drop electrode polarography (Metrohm 797 VA Computrace). SA enrichment factors (EF: SML SA / underlying water SA) >1 were observed at most locations, showing the SML to be consistently SA-enriched along the entire cruise transect. The persistence of these enrichments up to wind speeds 12m s-¹ support previous conclusions regarding the stability of the SML under high winds. More specifically, SA in the SML was up to four-fold higher in the Atlantic Northern Hemisphere than in the Atlantic Southern Hemisphere. Even so, EF values were not significantly different between the two hemispheres (p >0.05). These various findings have potentially important implications for kw variability across ocean basin scales.

Spatial Homogeneity of Bacterial Communities Associated with the Surface Mucus Layer of the Reef-Building Coral Acropora palmata.

PubMed

Kemp, Dustin W; Rivers, Adam R; Kemp, Keri M; Lipp, Erin K; Porter, James W; Wares, John P

2015-01-01

Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions--uppermost (high irradiance), underside (low irradiance), and the colony base--representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.

Abundance and Distribution Characteristics of Microplastics in Surface Seawaters of the Incheon/Kyeonggi Coastal Region.

PubMed

Chae, Doo-Hyeon; Kim, In-Sung; Kim, Seung-Kyu; Song, Young Kyoung; Shim, Won Joon

2015-10-01

Microplastics in marine environments are of emerging concern due to their widespread distribution, their ingestion by various marine organisms, and their roles as a source and transfer vector of toxic chemicals. However, our understanding of their abundance and distribution characteristics in surface seawater (SSW) remains limited. We investigated microplastics in the surface microlayer (SML) and the SSW at 12 stations near-shore and offshore of the Korean west coast, Incheon/Kyeonggi region. Variation between stations, sampling media, and sampling methods were compared based on abundances, size distribution, and composition profiles of microsized synthetic polymer particles. The abundance of microplastics was greater in the SML (152,688 ± 92,384 particles/m(3)) than in SSW and showed a significant difference based on the sampling method for SSWs collected using a hand net (1602 ± 1274 particles/m(3)) and a zooplankton trawl net (0.19 ± 0.14 particles/m(3)). Ship paint particles (mostly alkyd resin polymer) accounted for the majority of microplastics detected in both SML and SSWs, and increased levels were observed around the voyage routes of large vessels. This indicates that polymers with marine-based origins become an important contributor to microplastics in coastal SSWs of this coastal region.

A numerical analysis of carbon dynamics of the Southern Ocean phytoplankton community: the roles of light and grazing in effecting both sequestration of atmospheric CO 2 and food availability to larval krill

NASA Astrophysics Data System (ADS)

Walsh, John J.; Dieterle, Dwight A.; Lenes, Jason

2001-01-01

Reduced ice extent within coastal regions of the Southern Ocean may lead to deeper surface mixed layers (SML), as prevail in offshore areas. A future decline of ice melt-induced stability of the water column may be associated with a shift in dominant food webs, from larger, sun-adapted diatoms grazed by euphausiids to smaller, shade-adapted flagellates consumed by salps. A basically one-dimensional numerical model of three dominant groups of the Antarctic phytoplankton community (diatoms, cryptophytes, and colonial prymnesiophytes) and four types of herbivore (protozoans, salps, copepods, and euphausiids) is used to explore the seasonal importance of both light limitation and grazing pressure on the amount of annual carbon sequestration and larval krill survival within contrasting oceanic and neritic waters, where respective validation data have been gathered during austral spring by the European JGOFS and RACER programs. With imposition of moderate and large grazing stresses, thought to be typical of offshore waters, we were able to replicate the European JGOFS 1992 observations of light penetration, phytoplankton biomass, primary production, pCO 2, bacterial biomass, labile DOC, ammonium, and total particle effluxes at 100 m within the deep SML of our model. The fidelity of such a large set of simulated state variables suggests that multiple limiting factors are indeed operating on different components of the oceanic phytoplankton community — selective grazing losses on the flagellates, but light limitation of diatoms. Release of protozoan grazing pressure in our model instead leads to unobserved spring blooms of cryptophytes, found only in laboratory enclosures. On an annual basis, weak sequestration of atmospheric CO 2 is simulated in a habitat typical of the Polar Front, while evasion of carbon dioxide occurs under biophysical conditions of the Antarctic Circumpolar Current. Stratification in shallow SML and the same absolute grazing demands by krill and copepods allows sun-adapted diatoms of our model to bloom at the expense of shade-adapted cryptophytes and prymnesiophytes, eaten by salps and protozoans. We were also able to replicate RACER-I observations of the same suite of variables in 1986-1987, as well as the observed 10-fold range of detrital fluxes caught by other sediment trap deployments during 1980 and 1983 along the Antarctic Peninsula. In western Bransfield Strait, coastal waters are a strong sink for atmospheric CO 2 within parcels of Bellingshausen Sea origin, but not perhaps in those from the Weddell Sea, which resemble the oceanic regime of deep SML. We conclude that even in shallow neritic SML, some protozoan rivals of larval krill must still crop flagellates to ensure sufficient abundance of diatom food for both euphausiid survival and possible clogging of the mucous nets of other salp rivals.

On the chemical dynamics of extracellular polysaccharides in the high Arctic surface microlayer

NASA Astrophysics Data System (ADS)

Gao, Q.; Leck, C.; Rauschenberg, C.; Matrai, P. A.

2012-07-01

The surface microlayer (SML) represents a unique system of which the physicochemical characteristics may differ from those of the underlying subsurface seawater (SSW). Within the Arctic pack ice area, the SML has been characterized as enriched in small colloids of biological origin, resulting from extracellular polymeric secretions (EPS). During the Arctic Summer Cloud Ocean Study (ASCOS) in August 2008, particulate organic matter (POM, with size range > 0.22 μm) and dissolved organic matter (DOM, < 0.22 μm, obtained after filtration) samples were collected and chemically characterized from the SML and the corresponding SSW at an open lead centered at 87.5° N and 5° E. Total organic carbon was persistently enriched in the SML with a mean enrichment factor (EF) of 1.45 ± 0.41, whereas sporadic depletions of dissolved carbohydrates and amino acids were observed. Monosaccharide compositional analysis reveals that EPS in the Arctic lead was formed mainly of distinctive heteropolysaccharides, enriched in xylose, fucose and glucose. The mean concentrations of total hydrolysable neutral sugars in SSW were 94.9 ± 37.5 nM in high molecular weight (HMW) DOM (> 5 kDa) and 64.4 ± 14.5 nM in POM. The enrichment of polysaccharides in the SML appeared to be a common feature, with EFs ranging from 1.7 to 7.0 for particulate polysaccharides and 3.5 to 12.1 for polysaccharides in the HMW DOM fraction. A calculated monosaccharide yield suggests that polymers in the HMW DOM fraction were scavenged, without substantial degradation, into the SML. Bubble scavenging experiments showed that newly aggregated particles could be formed abiotically by coagulation of low molecular weight nanometer-sized gels. Aerosol particles, artificially generated by bubbling experiments, were enriched in polysaccharides by factors of 22-70, relative to the source seawater. We propose that bubble scavenging of surface-active polysaccharides could be one of the possible mechanisms for the enrichment of polysaccharides in the high Arctic open lead SML.

On the chemical dynamics of extracellular polysaccharides in the high Arctic surface microlayer

NASA Astrophysics Data System (ADS)

Gao, Q.; Leck, C.; Rauschenberg, C.; Matrai, P. A.

2012-01-01

The surface microlayer (SML) represents a unique system of which the physicochemical characteristics may differ from those of the underlying subsurface seawater (SSW). Within the Arctic pack ice area, the SML has been characterized as enriched in small colloids of biological origin, resulting from extracellular polymeric secretions (EPS). During the Arctic Summer Cloud-Ocean Study (ASCOS) in August 2008, particulate and dissolved organic matter (POM, DOM) samples were collected and chemically characterized from the SML and the corresponding SSW at an open lead centered at 87.5° N and 5° E. Total organic carbon was persistently enriched in the SML with a mean enrichment factor (EF) of 1.45 ± 0.41, whereas sporadic depletions of dissolved carbohydrates and amino acids were observed. Monosaccharide compositional analysis reveals that EPS in the Arctic lead was formed mainly of distinctive heteropolysaccharides, enriched in xylose, fucose and glucose. The mean concentrations of total hydrolysable neutral sugars in SSW were 94.9 ± 37.5 nM in high molecular weight (HMW) DOM and 64.4 ± 14.5 nM in POM. The enrichment of polysaccharides in the SML appeared to be a common feature, with EFs ranging from 1.7 to 7.0 for particulate polysaccharides and 3.5 to 12.1 for polysaccharides in the HMW DOM fraction. A calculated monosaccharide yield suggests that polymers in the HMW DOM fraction were scavenged, without substantial degradation, into the SML. Bubble scavenging experiments showed that newly aggregated particles could be formed abiotically by coagulation of low molecular weight nanometer-sized gels. Experimentally-generated aerosol particles were enriched in polysaccharides by factors of 22-70, relative to the source seawater. We propose that bubble scavenging of surface-active polysaccharides was one of the possible mechanisms for the enrichment of polysaccharides in the SML.

Changes in optical characteristics of surface microlayers hint to photochemically and microbially mediated DOM turnover in the upwelling region off the coast of Peru

NASA Astrophysics Data System (ADS)

Galgani, Luisa; Engel, Anja

2016-04-01

The coastal upwelling system off the coast of Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. From 3 to 23 December 2012, R/V Meteor (M91) cruise took place in the Peruvian upwelling system between 4.59 and 15.4° S, and 82.0 to 77.5° W. During M91 we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like chromophoric dissolved organic matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. We analyzed SML and underlying water (ULW) samples at 38 stations focusing on CDOM spectral characteristics as indicator of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and excitation-emission matrix fluorescence (EEMs), which allow us to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. Spectral slope S varied between 0.012 to 0.043 nm-1 and was quite similar between SML and ULW, with no significant differences between the two compartments. Higher S values were observed in the ULW of the southern stations below 15° S. By EEMs, we identified five fluorescent components (F1-5) of the CDOM pool, of which two had excitation/emission characteristics of amino-acid-like fluorophores (F1, F4) and were highly enriched in the SML, with a median ratio SML : ULW of 1.5 for both fluorophores. In the study region, values for CDOM absorption ranged from 0.07 to 1.47 m-1. CDOM was generally highly concentrated in the SML, with a median enrichment with respect to the ULW of 1.2. CDOM composition and changes in spectral slope properties suggested a local microbial release of DOM directly in the SML as a response to light exposure in this extreme environment. In a conceptual model of the sources and modifications of optically active DOM in the SML and underlying seawater (ULW), we describe processes we think may take place (Fig. 1); the production of CDOM of higher MW by microbial release through growth, exudation and lysis in the euphotic zone, includes the identified fluorophores (F1, F2, F3, F4, F5). Specific amino-acid-like fluorophores (F1, F4) accumulate in the SML with respect to the ULW, as photochemistry may enhance microbial CDOM release by (a) photoprotection mechanisms and (b) cell-lysis processes. Microbial and photochemical degradation are potential sinks of the amino-acid-like fluorophores (F1, F4), and potential sources of reworked and more refractory humic-like components (F2, F3, F5). In the highly productive upwelling region along the Peruvian coast, the interplay of microbial and photochemical processes controls the enrichment of amino-acid-like CDOM in the SML. We discuss potential implications for air-sea gas exchange in this area.

Effect of temperature on the accumulation of marine biogenic gels in the surface microlayer near the outlet of nuclear power plants and adjacent areas in the Daya Bay, China.

PubMed

Yue, Wei-Zhong; Sun, Cui-Ci; Shi, Ping; Engel, Anja; Wang, You-Shao; He, Wei-Hong

2018-01-01

The surface microlayer (SML) in marine systems is often characterized by an enrichment of biogenic, gel-like particles, such as the polysaccharide-containing transparent exopolymer particles (TEP) and the protein-containing Coomassie stainable particles (CSP). This study investigated the distribution of TEP and CSP, in the SML and underlying water, as well as their bio-physical controlling factors in Daya Bay, an area impacted by warm discharge from two Nuclear power plants (Npp's) and aquaculture during a research cruise in July 2014. The SML had higher proportions of cyanobacteria and of pico-size Chl a contrast to the underlayer water, particularly at the nearest outlet station characterized by higher temperature. Diatoms, dinoflagellates and chlorophyll a were depleted in the SML. Both CSP and TEP abundance and total area were enriched in the SML relative to the underlying water, with enrichment factors (EFs) of 1.5-3.4 for CSP numbers and 1.32-3.2 for TEP numbers. Although TEP and CSP showed highest concentration in the region where high productivity and high nutrient concertation were observed, EFs of gels and of dissolved organic carbon (DOC) and dissolved acidic polysaccharide (> 1 kDa), exhibited higher values near the outlet of the Npp's than in the adjacent waters. The positive relation between EF's of gels and temperature and the enrichment of cyanobacteria in the SML may be indicative of future conditions in a warmer ocean, suggesting potential effects on adjusting phytoplankton community, biogenic element cycling and air-sea exchange processes.

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer

DOE PAGES

Engel, Anja; Bange, Hermann W.; Cunliffe, Michael; ...

2017-05-30

Despite the huge extent of the ocean’s surface, until now relatively little attention has been paid to the sea surface microlayer (SML) as the ultimate interface where heat, momentum and mass exchange between the ocean and the atmosphere takes place. Via the SML, large-scale environmental changes in the ocean such as warming, acidification, deoxygenation, and eutrophication potentially influence cloud formation, precipitation, and the global radiation balance. Due to the deep connectivity between biological, chemical, and physical processes, studies of the SML may reveal multiple sensitivities to global and regional changes. Understanding the processes at the ocean’s surface, in particular involvingmore » the SML as an important and determinant interface, could therefore provide an essential contribution to the reduction of uncertainties regarding ocean-climate feedbacks. This review identifies gaps in our current knowledge of the SML and highlights a need to develop a holistic and mechanistic understanding of the diverse biological, chemical, and physical processes occurring at the ocean-atmosphere interface. We advocate the development of strong interdisciplinary expertise and collaboration in order to bridge between ocean and atmospheric sciences. Although this will pose significant methodological challenges, such an initiative would represent a new role model for interdisciplinary research in Earth System sciences.« less

The bacterial community composition of the surface microlayer in a high mountain lake.

PubMed

Hörtnagl, Paul; Pérez, Maria Teresa; Zeder, Michael; Sommaruga, Ruben

2010-09-01

The existence of bacterioneuston in aquatic ecosystems is well established, but little is known about its composition and dynamics, particularly in lakes. The bacterioneuston underlies extreme conditions at the air-water boundary, which may influence its dynamics in a different way compared with the bacterioplankton. In this study, we assessed quantitative changes in major bacterial groups of the surface microlayer (SML) (upper 900 microm) and the underlying water (ULW) (0.2-0.5 m depth) of an alpine lake during two consecutive ice-free seasons. Analysis of the bacterial community composition was done using catalyzed reporter deposition FISH with oligonucleotide probes. In addition, several physicochemical parameters were measured to characterize these two water layers. Dissolved organic carbon was consistently enriched in the SML and the dissolved organic matter pool presented clear signals of photodegradation and photobleaching. The water temperature was generally colder in the SML than in the subsurface. The bacterial community of the SML and the ULW was dominated by Betaproteobacteria and Actinobacteria. The bacterial community composition was associated with different combinations of physicochemical factors in these two layers, but temporal changes showed similar trends in both layers over the two seasons. Our results identify the SML of alpine lakes as a microhabitat where specific bacterial members such as of Betaproteobacteria seem to be efficient colonizers.

Web-Based Media Literacy to Prevent Tobacco Use among High School Students

ERIC Educational Resources Information Center

Phelps-Tschang, Jane S.; Miller, Elizabeth; Rice, Kristen; Primack, Brian A.

2015-01-01

Facilitator-led smoking media literacy (SML) programs have improved media literacy and reduced intention to smoke. However, these programs face limitations including high costs and barriers to standardization. We examined the efficacy of a Web-based media literacy program in improving smoking media literacy skills among adolescents. Sixty-six 9th…

Changes in optical characteristics of surface microlayers hint to photochemically and microbially-mediated DOM turnover in the upwelling region off Peru

NASA Astrophysics Data System (ADS)

Galgani, L.; Engel, A.

2015-12-01

The coastal upwelling system off Peru is characterized by high biological activity and a pronounced subsurface oxygen minimum zone, as well as associated emissions of atmospheric trace gases such as N2O, CH4 and CO2. During the Meteor (M91) cruise to the Peruvian upwelling system in 2012, we investigated the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples at 38 stations determining DOC concentration, amino acid composition, marine gels, CDOM and bacterial and phytoplankton abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slope (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources and sinks. We identified five fluorescent components of the CDOM pool, of which two had excitation/emission characteristics of protein-like fluorophores and were highly enriched in the SML. CDOM composition and changes in spectral slope properties suggested a local microbial release of HMW DOM directly in the SML as a response to light exposure in this extreme environment. Our results suggest that microbial and photochemical processes play an important role for the production, alteration and loss of optically active substances in the SML.

Sterols as biomarkers in the surface microlayer of the estuarine areas.

PubMed

Alsalahi, Murad Ali; Latif, Mohd Talib; Ali, Masni Mohd; Dominick, Doreena; Khan, Md Firoz; Mustaffa, Nur Ili Hamizah; Nadzir, Mohd Shahrul Mohd; Nasher, Essam; Zakaria, Mohamad Pauzi

2015-04-15

This study aims to determine the concentration of sterols used as biomarkers in the surface microlayer (SML) in estuarine areas of the Selangor River, Malaysia. Samples were collected during different seasons through the use of a rotation drum. The analysis of sterols was performed using gas chromatography equipped with a flame ionisation detector (GC-FID). The results showed that the concentrations of total sterols in the SML ranged from 107.06 to 505.55 ng L(-1). The total sterol concentration was found to be higher in the wet season. Cholesterol was found to be the most abundant sterols component in the SML. The diagnostic ratios of sterols show the influence of natural sources and waste on the contribution of sterols in the SML. Further analysis, using principal component analysis (PCA), showed distinct inputs of sterols derived from human activity (40.58%), terrigenous and plant inputs (22.59%) as well as phytoplankton and marine inputs (17.35%). Copyright © 2015 Elsevier Ltd. All rights reserved.

Surfactants in the sea-surface microlayer and atmospheric aerosol around the southern region of Peninsular Malaysia.

PubMed

Jaafar, Shoffian Amin; Latif, Mohd Talib; Chian, Chong Woan; Han, Wong Sook; Wahid, Nurul Bahiyah Abd; Razak, Intan Suraya; Khan, Md Firoz; Tahir, Norhayati Mohd

2014-07-15

This study was conducted to determine the composition of surfactants in the sea-surface microlayer (SML) and atmospheric aerosol around the southern region of the Peninsular Malaysia. Surfactants in samples taken from the SML and atmospheric aerosol were determined using a colorimetric method, as either methylene blue active substances (MBAS) or disulphine blue active substances (DBAS). Principal component analysis with multiple linear regressions (PCA-MLR), using the anion and major element composition of the aerosol samples, was used to determine possible sources of surfactants in atmospheric aerosol. The results showed that the concentrations of surfactants in the SML and atmospheric aerosol were dominated by anionic surfactants and that surfactants in aerosol were not directly correlated (p>0.05) with surfactants in the SML. Further PCA-MLR from anion and major element concentrations showed that combustion of fossil fuel and sea spray were the major contributors to surfactants in aerosol in the study area. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study on organic matter fractions in the surface microlayer in the Baltic Sea by spectrophotometric and spectrofluorometric methods

NASA Astrophysics Data System (ADS)

Drozdowska, Violetta; Wrobel, Iwona; Markuszewski, Piotr; Makuch, Przemysław; Raczkowska, Anna; Kowalczuk, Piotr

2017-08-01

The fluorescence and absorption measurements of the samples collected from a surface microlayer (SML) and a subsurface layer (SS), at a depth of 1 m, were studied during three research cruises in the Baltic Sea along with hydrophysical studies and meteorological observations. Several absorption (E2 : E3, S, SR) and fluorescence (fluorescence intensities at Coble classified peaks: A, C, M, T the ratio M + T/A + C, HIX (humification index)) indices of colored and fluorescent dissolved organic matter (CDOM and FDOM) helped to describe the changes in molecular size and weight as well as in composition of organic matter. The investigation allowed the assessment of a decrease in the contribution of two terrestrial components (A and C) with increasing salinity ( ˜ 1.64 and ˜ 1.89 % in the SML and ˜ 0.78 and ˜ 0.71 % in the SS, respectively) and an increase in components produced in situ (M and T) with salinity ( ˜ 0.52 and ˜ 2.83 % in the SML and ˜ 0.98 and ˜ 1.87 % in the SS, respectively). Hence, a component T reveals the biggest relative changes along the transect from the Vistula River outlet to Gdansk Deep, in both the SML and SS, although an increase was higher in the SML than in the SS ( ˜ 18.5 and ˜ 12.3 %, respectively). The ratio E2 : E3 points to greater changes in the molecular weight of CDOM affected by a higher rate of photobleaching in the SML. The HIX index reflects a more advanced stage of humification and condensation processes in the SS. Finally, the results reveal a higher rate of degradation processes occurring in the SML than in the SS. Thus, the specific physical properties of surface active organic molecules (surfactants) may modify, in a specific way, the solar light spectrum entering the sea and a penetration depth of the solar radiation. Research on the influence of surfactants on the physical processes linked to the sea surface becomes an important task, especially in coastal waters and in the vicinity of the river mouths.

Analytical screening of polyadipates and other plasticisers in poly(vinyl chloride) gasket seals and in fatty food by gas chromatography-mass spectrometry.

PubMed

Ezerskis, Z; Morkūnas, V; Suman, M; Simoneau, C

2007-11-26

Fourteen poly(vinyl chloride) (PVC) gasket seals and 15 samples of pesto, tomatoes sauces, olive oil and olives in oil were analysed for the additives and plasticisers. The systematic screening of the representative samples revealed that epoxidised soybean oil (ESBO) was the principal plasticiser in eight gaskets and the concentrations of the substance ranged from 15% to 42%. Diisodecyl phthalate (DIDP) as main plasticiser was revealed in three samples and the amount ranged from 37 to 41%. Polyadipate was added in four samples at 16-46%. The concentration of ESBO exceeded 60 mg kg(-1) in three food samples with extreme at 281.9 mg kg(-1) and average 61.3 mg kg(-1). Di-(2-ethylhexyl) phthalate (DEHP) was detected in six food samples and it ranged from 2.5 to 8.7 mg kg(-1). The concentration of DEHP exceeded SML (3 mg kg(-1)) in five cases. The concentration of total polyadipate (PA) was 16.3 mg kg(-1) in average. All eight positive food samples for total PA showed the concentrations below SML (30 mg kg(-1)), which are specified for the fraction of polyadipates lower than 1000 Da. The migration rate of polyadipate in the food ranged from 1 to 7%. At such low transfer rate the polyadipates could be promising plasticisers for PVC gasket seals used in food industry.

From Social Movement Learning to Sociomaterial Movement Learning? Addressing the Possibilities and Limits of New Materialism

ERIC Educational Resources Information Center

McGregor, Callum

2014-01-01

In recent years academic interest in social movement learning (SML) has flourished. "Studies in the Education of Adults" has arguably emerged as the premier international forum for exploring the links between adult learning and movements for progressive change. In parallel to this subfield, yet largely in isolation from it,…

Smoking Media Literacy in Vietnamese Adolescents

ERIC Educational Resources Information Center

Page, Randy M.; Huong, Nguyen T.; Chi, Hoang K.; Tien, Truong Q.

2011-01-01

Background: Smoking media literacy (SML) has been found to be independently associated with reduced current smoking and reduced susceptibility to future smoking in a sample of American adolescents, but not in other populations of adolescents. Thus, the purpose of this study was to assess SML in Vietnamese adolescents and to determine the…

Identification of intentionally and non-intentionally added substances in plastic packaging materials and their migration into food products.

PubMed

García Ibarra, Verónica; Rodríguez Bernaldo de Quirós, Ana; Paseiro Losada, Perfecto; Sendón, Raquel

2018-05-07

Plastic materials are widely used in food packaging applications; however, there is increased concern because of the possible release of undesirable components into foodstuffs. Migration of plastic constituents not only has the potential to affect product quality but also constitutes a risk to consumer health. In order to check the safety of food contact materials, analytical methodologies to identify potential migrants are required. In the first part of this work, a GC/MS screening method was developed for the identification of components from plastic packaging materials including intentionally and "non-intentionally added substances" (NIAS) as potential migrants. In the second part of this study, the presence of seven compounds (bis (2-ethylhexyl) phthalate (DEHP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), butylated hydroxytoluene (BHT), acetyl tributyl citrate (ATBC), benzophenone (BP)) previously identified in packaging materials were investigated in food products (corn and potatoes snacks, cookies, and cakes). For this purpose, a suitable extraction method was developed and quantification was performed using GC-MS. The developed method was validated in terms of linearity, recovery, repeatability, and limits of detection and quantification. The spiked recoveries varied between 82.7 and 116.1%, and relative standard deviation (RSD) was in the range of 2.22-15.9%. The plasticizer ATBC was the most detected compound (94% samples), followed by DEP (65%), DEHP (47%), BP (44%), DBP (35%), DIBP (21%), and BHT (12%). Regarding phthalates, DEP and DEHP were the most frequently detected compounds in concentrations up to 1.44 μg g -1 . In some samples, only DBP exceeded the European SML of 0.3 mg kg -1 established in Regulation 10/2011. Graphical abstract Chemical migration from plastic packaging into food.

A Randomized Crossover Study of Web-Based Media Literacy to Prevent Smoking

ERIC Educational Resources Information Center

Shensa, Ariel; Phelps-Tschang, Jane; Miller, Elizabeth; Primack, Brian A.

2016-01-01

Feasibly implemented Web-based smoking media literacy (SML) programs have been associated with improving SML skills among adolescents. However, prior evaluations have generally had weak experimental designs. We aimed to examine program efficacy using a more rigorous crossover design. Seventy-two ninth grade students completed a Web-based SML…

Occurrence and distribution of hydrocarbons in the surface microlayer and subsurface water from the urban coastal marine area off Marseilles, Northwestern Mediterranean Sea.

PubMed

Guigue, Catherine; Tedetti, Marc; Giorgi, Sébastien; Goutx, Madeleine

2011-12-01

Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed in dissolved and particulate material from surface microlayer (SML) and subsurface water (SSW) sampled at nearshore observation stations, sewage effluents and harbour sites from Marseilles coastal area (Northwestern Mediterranean) in 2009 and 2010. Dissolved and particulate AH concentrations ranged 0.05-0.41 and 0.04-4.3 μg l(-1) in the SSW, peaking up to 38 and 1366 μg l(-1) in the SML, respectively. Dissolved and particulate PAHs ranged 1.9-98 and 1.9-21 ng l(-1) in the SSW, amounting up 217 and 1597 ng l(-1) in the SML, respectively. In harbours, hydrocarbons were concentrated in the SML, with enrichment factors reaching 1138 for particulate AHs. Besides episodic dominance of biogenic and pyrogenic inputs, a moderate anthropisation from petrogenic sources dominated suggesting the impact of shipping traffic and surface runoffs on this urbanised area. Rainfalls increased hydrocarbon concentrations by a factor 1.9-11.5 in the dissolved phase. Copyright © 2011 Elsevier Ltd. All rights reserved.

Are additive effects of dietary surfactants on intestinal tight junction integrity an overlooked human health risk? - A mixture study on Caco-2 monolayers.

PubMed

Glynn, Anders; Igra, Annachiara Malin; Sand, Salomon; Ilbäck, Nils Gunnar; Hellenäs, Karl Erik; Rosén, Johan; Aspenström-Fagerlund, Bitte

2017-08-01

Surfactants may cause dysfunction of intestinal tight junctions (TJs), which is a common feature of intestinal autoimmune diseases. Effects of dietary surfactants on TJ integrity, measured as trans-epithelial resistance (TEER), were studied in Caco-2 cell monolayers. Cytotoxicity was assessed as apical LDH leakage. Monolayers were apically exposed for 60 min to the dietary surfactants solanine and chaconine (SC, potato glycoalkaloids, 0-0.25 mM), perfluorooctane sulfonic acid (PFOS, industrial contaminant, 0-0.8 mM), and sucrose monolaurate (SML, food emulsifier E 473, 0-2.0 mM) separately and as a mixture. Dose-response modelling of TEER EC 50 showed that SC were 2.7- and 12-fold more potent than PFOS and SML, respectively. The mixture was composed of 1 molar unit SC, 2.7 units PFOS and 12 units SML ("SC TEER equivalent" proportions 1:1:1). Mixture exposure (0-0.05 mM SC equivalents) dose-response modelling suggested additive action on TJ integrity. Increasing SC and SML concentrations caused increased LDH leakage, but PFOS decreased LDH leakage at intermediate exposure concentrations. In the mixture PFOS appeared to protect from extensive SC- and SML-induced LDH leakage. Complex mixtures of surfactants in food may act additively on intestinal TJ integrity, which should be considered in risk assessment of emulsifier authorisation for use in food production. Copyright © 2017 Elsevier Ltd. All rights reserved.

The potential roles of bacterial communities in coral defence: A case study at Talang-talang reef

NASA Astrophysics Data System (ADS)

Kuek, Felicity W. I.; Lim, Li-Fang; Ngu, Lin-Hui; Mujahid, Aazani; Lim, Po-Teen; Leaw, Chui-Pin; Müller, Moritz

2015-06-01

Complex microbial communities are known to exert significant influence over coral reef ecosystems. The Talang- Satang National Park is situated off the coast of Sematan and is one of the most diverse ecosystems found off-Sarawak. Interestingly, the Talang-talang reef thrives at above-average temperatures of 28- 30°C throughout the year. Through isolation and identification (16S rRNA) of native microbes from the coral, the surface mucus layer (SML), as well as the surrounding sediment and waters, we were able to determine the species composition and abundance of the culturable bacteria in the coral reef ecosystem. Isolates found attached to the coral are related mostly to Vibrio spp., presumably attached to the mucus from the water column and surrounding sediment. Pathogenic Vibrio spp. and Bacillus spp. were dominant amongst the isolates from the water column and sediment, while known coral pathogens responsible for coral bleaching, Vibrio coralliilyticus and Vibrio shiloi, were isolated from the coral SML and sediment samples respectively. Coral SML isolates were found to be closely related to known nitrogen fixers and antibiotic producers with tolerance towards elevated temperatures and heavy metal contamination, offering a possible explanation why the local corals are able to thrive in higher than usual temperatures. This specialized microbiota may be important for protecting the corals from pathogens by occupying entry niches and/or through the production of secondary metabolites such as antibiotics. The communities from the coral SML were tested against each other at 28, 30 and 32°C, and were also assessed for the presence of type I modular polyketides synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes which are both involved in the production of antibiotic compounds. The bacterial community from the SML exhibited antimicrobial properties under normal temperatures while pathogenic strains appeared toxic at elevated temperatures and our results highlight the role of the coral SML bacterial community in the coral's defence.

Encapsulation, controlled release, and antitumor efficacy of cisplatin delivered in liposomes composed of sterol-modified phospholipids

DOE PAGES

Kieler-Ferguson, Heidi M.; Chan, Darren; Sockolosky, Jonathan; ...

2017-03-03

Here, we employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shortermore » acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48 h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.« less

Encapsulation, controlled release, and antitumor efficacy of cisplatin delivered in liposomes composed of sterol-modified phospholipids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieler-Ferguson, Heidi M.; Chan, Darren; Sockolosky, Jonathan

Here, we employed a recently introduced class of sterol-modified lipids (SML) to produce m-PEG-DSPE containing liposome compositions with a range of cis-platinum content release rates. SML have a cholesterol succinate attached to the phosphatidylglycerol head group and a fatty acid at the 2 position. These compositions were compared to the well-studied liposome phospholipid compositions: mPEG-DSPE/Hydrogenated Soy PC/cholesterol or mPEG-DSPE/POPC/cholesterol to determine the effect of the cis-platinum release extent on C26 tumor proliferation in the BALB/c colon carcinoma mouse model. The release rates of cis-platinum from liposomes composed of SML are a function of the acyl chain length. SML-liposomes with shortermore » acyl chain lengths C-8 provided more rapid cisplatin release, lower in vitro IC50, and were easier to formulate compared to liposomes using traditional phospholipid compositions. Similar to other liposome cis-platinum formulations, the half-life of m-PEG-DSPE SML liposome cisplatin is substantially longer than the free drug. This resulted in a higher tumor cisplatin concentration at 48 h post-dosing compared to the free drug and higher Pt-DNA adducts in the tumor. Moreover, the maximum tolerated dose of the liposome formulations where up to four fold greater than the free drug. Using X-ray fluorescence spectroscopy on tumor sections, we compared the location of platinum, to the location of a fluorescence lipid incorporated in the liposomes. The liposome platinum co-localized with the fluorescent lipid and both were non-uniformly distributed in the tumor. Non-encapsulated Cis-platinum, albeit at a low concentration, was more uniformly distributed thorough the tumor. Three liposome formulations, including the well studied hydrogenated HSPC composition, had better antitumor activity in the murine colon 26 carcinoma model as compared to the free drug at the same dose but the SML liposome platinum formulations did not perform better than the HSPC formulation.« less

Effects of Salvia miltiorrhiza extract with supplemental liquefied calcium on osteoporosis in calcium-deficient ovariectomized mice.

PubMed

Park, Bongkyun; Song, Hae Seong; Kwon, Jeong Eun; Cho, Se Min; Jang, Seon-A; Kim, Mi Yeon; Kang, Se Chan

2017-12-20

Extracts from Salvia miltiorrhiza Bunge have been used in traditional Asian medicine to treat coronary heart disease, chronic renal failure, atherosclerosis, myocardial infraction, angina pectoris, myocardial ischemia, dysmenorrheal, neurasthenic insomnia, liver fibrosis and cirrhosis. The aim of the study was to investigate the anti-RANK signal effect of the combination of S.miltiorrhiza Bunge (SME) and liquefied calcium (LCa) supplement with ovariectomized (OVX-SML) mice, a osteoporosis animal model. Results were compared to 17β-estradiol (E 2 ) treatment. A total of 70 female ICR strain mice (7 weeks) were randomly divided into 10 groups with 7 mice in each group as follows: (1) sham-operated control mice (sham) received daily oral phosphate-buffered-saline (PBS) of equal volumes through oral administration. (2) OVX mice received a daily oral administration of PBS (OVX). (3) OVX mice treated daily with 50 mg/kg b.w./ day of SME (4) with 100 mg/kg b.w./day of SME or (5) with 200 mg/kg b.w./day of SME via oral administration. (6) OVX mice treated daily with 50 mg/kg b.w./day of SML (7) with 100 mg/kg b.w./day of SML or (8) with 200 mg/kg b.w./day of SML via oral administration. (9) OVX mice treated daily with 10 ml/kg b.w./day of LCa (10) OVX mice received i.p. injections of 17β-estradiol (E 2 ) (0.1 mg/kg b.w./day) three times per week for 12 weeks. micro-CT analysis revealed that oral administration of SML inhibited tibial bone loss, sustained trabecular bone state, and ameliorated bone biochemical markers. In addition, SML administration compared to SEM and LCa reduced serum levels of RANKL, osteocalcin and BALP through increased serum levels of OPG and E 2 in OVX mice. SML also had more beneficial effects on protection of estrogen-dependent bone loss through blocking expression of TRAF6 and NFTAc1 and produces cathepsin K and calcitonin receptor to develop osteoclast differentiation. These data suggest that S. miltiorrhiza Bunge combined with liquefied calcium supplement has an inhibitory activity in OVX mice. This result implies the possibility of a pharmacological intervention specifically directed toward a disease such as osteoporosis where decreased bone strength increases the risk of a broken bone .

Synthetic ultraviolet light filtering chemical contamination of coastal waters of Virgin Islands National Park, St. John, U.S. Virgin Islands

USGS Publications Warehouse

Bargar, Timothy A.; Alvarez, David; Garrison, Virginia H.

2015-01-01

Contamination of surface waters by synthetic ultraviolet light (UV) filtering chemicals is a concern for the Virgin Islands National Park (VINP). Discrete water samples were collected from VINP bays to determine UV filter chemical presence in the coastal waters. Spatial distribution and the potential for partitioning between subsurface waters and the sea surface microlayer (SML) were also examined. The UV filter chemicals 4-methylbenzylidene camphor, benzophenone-3, octinoxate, homosalate, and octocrylene were detected at concentrations up to 6073 ng/L (benzophenone-3). Concentrations for benzophenone-3 and homosalate declined exponentially (r2 = 0.86 to 0.98) with distance from the beach. Limited data indicate that some UV filter chemicals may partition to the SML relative to the subsurface waters. Contamination of VINP coastal waters by UV filter chemicals may be a significant issue, but an improved understanding of the temporal and spatial variability of their concentrations would be necessary to better understand the risk they present.

Evidence of the Value of the Smoking Media Literacy Framework for Middle School Students.

PubMed

Bier, Melinda C; Zwarun, Lara; Sherblom, Stephen A

2016-10-01

Susceptibility to future smoking, positive beliefs about smoking, and perceptions of antismoking norms are all factors that are associated with future smoking. In previous research, smoking media literacy (SML) has been associated with these variables, even when controlling for other known risk factors for smoking. However, these studies were performed with older teenagers, often in high school, not younger teens at a crucial developmental point with respect to the decision to begin smoking. This study uses survey data collected from 656 American public middle school students representing multiple zip codes, schools, and school districts. Smoking media literacy levels for middle school students were similar to those of high school students in earlier studies. Higher SML levels were associated with lower susceptibility to future smoking and predicted susceptibility to smoke when controlling for other risk factors. This suggests that the same relationships found with teenagers may exist with middle school students. Although follow-up studies using larger and more controlled administrations of the SML scale are warranted, this study suggests the utility of the SML framework and scale in the development and investigation of media literacy as a prevention strategy in students this age. © 2016, American School Health Association.

Biodiversity of the white coral bank off Cape Santa Maria di Leuca (Mediterranean Sea): An update

NASA Astrophysics Data System (ADS)

Mastrototaro, F.; D'Onghia, G.; Corriero, G.; Matarrese, A.; Maiorano, P.; Panetta, P.; Gherardi, M.; Longo, C.; Rosso, A.; Sciuto, F.; Sanfilippo, R.; Gravili, C.; Boero, F.; Taviani, M.; Tursi, A.

2010-03-01

The biodiversity of the Santa Maria di Leuca (SML) coral bank is summarized and its description is updated using data collected by means of underwater video systems, benthic samplers and fishing gears. A total of 222 living species have been recorded within the coral bank area in the depth range 280-1121 m. The most abundant benthic taxa recorded are Porifera (36 species) followed by Mollusca (35) and Cnidaria (31). The scleractinian corals Madrepora oculata and Lophelia pertusa are the main colonial species in the structure of the SML bank. Annelida, Crustacea and Bryozoa have been found with 24, 23 and 19 species, respectively. A total of 40 species of demersal fish have been recorded. Other faunal taxa were found with small numbers of species. One hundred and thirty-five species are new for the SML bank, 31 of which represent new records for the north-western Ionian Sea (2 Porifera, 17 Cnidaria, 1 Mollusca, 3 Annelida, 2 Crustacea, 4 Bryozoa and 4 Echinodermata). The finding of the annelid Harmothoë vesiculosa represents the first record for the Mediterranean Sea. The SML coral bank represents a biodiversity "hot-spot" on the bathyal bottoms of the Mediterranean Sea.

Bacterial assemblages differ between compartments within the coral holobiont

NASA Astrophysics Data System (ADS)

Sweet, M. J.; Croquer, A.; Bythell, J. C.

2011-03-01

It is widely accepted that corals are associated with a diverse and host species-specific microbiota, but how they are organized within their hosts remains poorly understood. Previous sampling techniques (blasted coral tissues, coral swabs and milked mucus) may preferentially sample from different compartments such as mucus, tissue and skeleton, or amalgamate them, making comparisons and generalizations between studies difficult. This study characterized bacterial communities of corals with minimal mechanical disruption and contamination from water, air and sediments from three compartments: surface mucus layer (SML), coral tissue and coral skeleton. A novel apparatus (the `snot sucker') was used to separate the SML from tissues and skeleton, and these three compartments were compared to swab samples and milked mucus along with adjacent environmental samples (water column and sediments). Bacterial 16S rRNA gene diversity was significantly different between the various coral compartments and environmental samples (PERMANOVA, F = 6.9, df = 8, P = 0.001), the only exceptions being the complete crushed coral samples and the coral skeleton, which were similar, because the skeleton represents a proportionally large volume and supports a relatively rich microflora. Milked mucus differed significantly from the SML collected with the `snot sucker' and was contaminated with zooxanthellae, suggesting that it may originate at least partially from the gastrovascular cavity rather than the tissue surface. A common method of sampling the SML, surface swabs, produced a bacterial community profile distinct from the SML sampled using our novel apparatus and also showed contamination from coral tissues. Our results indicate that microbial communities are spatially structured within the coral holobiont, and methods used to describe these need to be standardized to allow comparisons between studies.

Microhydrodynamics of flotation processes in the sea surface layer

NASA Astrophysics Data System (ADS)

Grammatika, Marianne; Zimmerman, William B.

2001-10-01

The uppermost surface of the ocean forms a peculiarly important ecosystem, the sea surface microlayer (SML). Comprising the top 1-1000 μm of the ocean surface, the SML concentrates many chemical substances, particularly those that are surface active. Important economically as a nursery for fish eggs and larvae, the SML unfortunately is also especially vulnerable to pollution. Contaminants that settle out from the air, have low solubility, or attach to floatable matter tend to accumulate in the SML. Bubbles contribute prominently to the dynamics of air-sea exchanges, playing an important role in geochemical cycling of material in the upper ocean and SML. In addition to the movement of bubbles, the development of a bubble cloud interrelates with the single particle dynamics of all other bubbles and particles. In the early sixties, several in situ oceanographic techniques revealed an "unbelievably immense" number of coastal bubbles of radius 15-300 μm. The spatial and temporal variation of bubble numbers were studied; acoustical oceanographers now use bubbles as tracers to determine ocean processes near the ocean surface. Sea state and rain noises have both been definitively ascribed to the radiation from huge numbers of infant micro bubbles [The Acoustic Bubble. Academic Press, San Diego]. Our research programme aims at constructing a hydrodynamic model for particle transport processes occurring at the microscale, in multi-phase flotation suspensions. Current research addresses bubble and floc microhydrodynamics as building blocks for a microscale transport model. This paper reviews sea surface transport processes in the microlayer and the lower atmosphere, and identifies those amenable to microhydrodynamic modelling and simulation. It presents preliminary simulation results including the multi-body hydrodynamic mobility functions for the modelling of "dynamic bubble filters" and floc suspensions. Hydrodynamic interactions versus spatial anisotropy and size of particle clouds are investigated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

March-Leuba, S.; Jansen, J.F.; Kress, R.L.

A new program package, Symbolic Manipulator Laboratory (SML), for the automatic generation of both kinematic and static manipulator models in symbolic form is presented. Critical design parameters may be identified and optimized using symbolic models as shown in the sample application presented for the Future Armor Rearm System (FARS) arm. The computer-aided development of the symbolic models yields equations with reduced numerical complexity. Important considerations have been placed on the closed form solutions simplification and on the user friendly operation. The main emphasis of this research is the development of a methodology which is implemented in a computer program capablemore » of generating symbolic kinematic and static forces models of manipulators. The fact that the models are obtained trigonometrically reduced is among the most significant results of this work and the most difficult to implement. Mathematica, a commercial program that allows symbolic manipulation, is used to implement the program package. SML is written such that the user can change any of the subroutines or create new ones easily. To assist the user, an on-line help has been written to make of SML a user friendly package. Some sample applications are presented. The design and optimization of the 5-degrees-of-freedom (DOF) FARS manipulator using SML is discussed. Finally, the kinematic and static models of two different 7-DOF manipulators are calculated symbolically.« less

Active Learning Strategies for Phenotypic Profiling of High-Content Screens.

PubMed

Smith, Kevin; Horvath, Peter

2014-06-01

High-content screening is a powerful method to discover new drugs and carry out basic biological research. Increasingly, high-content screens have come to rely on supervised machine learning (SML) to perform automatic phenotypic classification as an essential step of the analysis. However, this comes at a cost, namely, the labeled examples required to train the predictive model. Classification performance increases with the number of labeled examples, and because labeling examples demands time from an expert, the training process represents a significant time investment. Active learning strategies attempt to overcome this bottleneck by presenting the most relevant examples to the annotator, thereby achieving high accuracy while minimizing the cost of obtaining labeled data. In this article, we investigate the impact of active learning on single-cell-based phenotype recognition, using data from three large-scale RNA interference high-content screens representing diverse phenotypic profiling problems. We consider several combinations of active learning strategies and popular SML methods. Our results show that active learning significantly reduces the time cost and can be used to reveal the same phenotypic targets identified using SML. We also identify combinations of active learning strategies and SML methods which perform better than others on the phenotypic profiling problems we studied. © 2014 Society for Laboratory Automation and Screening.

Distributions of dissolved monosaccharides and polysaccharides in the surface microlayer and surface water of the Jiaozhou Bay and its adjacent area

NASA Astrophysics Data System (ADS)

Zhang, Yan-Ping; Yang, Gui-Peng; Lu, Xiao-Lan; Ding, Hai-Bing; Zhang, Hong-Hai

2013-07-01

Sea surface microlayer (SML) samples and corresponding bulk surface water (SW) samples were collected in the Jiaozhou Bay and its adjacent area in July and November 2008. The average concentrations of dissolved monosaccharides (MCHO) and polysaccharides (PCHO) revealed similar temporal variability, with higher concentrations during the green-tide period (in July) than during the non-green-tide period (in November). Average enrichment factors (EF) of MCHO and PCHO, defined as the ratio of the concentration in the SML to that in the SW, were 1.3 and 1.4 in July, respectively, while those values in November were 1.9 and 1.6. Our data also showed that the concentrations of MCHO and PCHO in the SML were strongly correlated with those in the SW, indicating that most of the organic materials in the SML came from the SW. The total dissolved carbohydrate concentrations (TDCHO) in the bulk surface water were closely correlated with salinity during the cruises (July: r=-0.580, n=18, P=0.01; November: r=-0.679, n=26, P<0.001), suggesting that riverine input had an important effect on the distribution of TDCHO in surface seawater of the study area.

A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples.

PubMed

Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Han, Gi Myung; Rani, Manviri; Lee, Jongmyoung; Shim, Won Joon

2015-04-15

The analysis of microplastics in various environmental samples requires the identification of microplastics from natural materials. The identification technique lacks a standardized protocol. Herein, stereomicroscope and Fourier transform infrared spectroscope (FT-IR) identification methods for microplastics (<1mm) were compared using the same samples from the sea surface microlayer (SML) and beach sand. Fragmented microplastics were significantly (p<0.05) underestimated and fiber was significantly overestimated using the stereomicroscope both in the SML and beach samples. The total abundance by FT-IR was higher than by microscope both in the SML and beach samples, but they were not significantly (p>0.05) different. Depending on the number of samples and the microplastic size range of interest, the appropriate identification method should be determined; selecting a suitable identification method for microplastics is crucial for evaluating microplastic pollution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Wavefront correction using machine learning methods for single molecule localization microscopy

NASA Astrophysics Data System (ADS)

Tehrani, Kayvan F.; Xu, Jianquan; Kner, Peter

2015-03-01

Optical Aberrations are a major challenge in imaging biological samples. In particular, in single molecule localization (SML) microscopy techniques (STORM, PALM, etc.) a high Strehl ratio point spread function (PSF) is necessary to achieve sub-diffraction resolution. Distortions in the PSF shape directly reduce the resolution of SML microscopy. The system aberrations caused by the imperfections in the optics and instruments can be compensated using Adaptive Optics (AO) techniques prior to imaging. However, aberrations caused by the biological sample, both static and dynamic, have to be dealt with in real time. A challenge for wavefront correction in SML microscopy is a robust optimization approach in the presence of noise because of the naturally high fluctuations in photon emission from single molecules. Here we demonstrate particle swarm optimization for real time correction of the wavefront using an intensity independent metric. We show that the particle swarm algorithm converges faster than the genetic algorithm for bright fluorophores.

Enrichment of Extracellular Carbonic Anhydrase in the Sea Surface Microlayer and Its Effect on Air-Sea CO2 Exchange

NASA Astrophysics Data System (ADS)

Mustaffa, N. I. H.; Striebel, M.; Wurl, O.

2017-12-01

This paper describes the quantification of extracellular carbonic anhydrase (eCA) concentrations in the sea surface microlayer (SML), the boundary layer between the ocean and the atmosphere of the Indo-West Pacific. We demonstrated that the SML is enriched with eCA by 1.5 ± 0.7 compared to the mixed underlying water. Enrichment remains up to a wind speed of 7 m s-1 (i.e., under typical oceanic conditions). As eCA catalyzes the interconversion of HCO3- and CO2, it has been hypothesized that its enrichment in the SML enhances the air-sea CO2 exchange. We detected concentrations in the range of 0.12 to 0.76 nM, which can enhance the exchange by up to 15% based on the model approach described in the literature.

Chemical Controls of Ozone Dry Deposition to the Sea Surface Microlayer

NASA Astrophysics Data System (ADS)

Carpenter, L.; Chance, R.; Tinel, L.; Saint, A.; Sherwen, T.; Loades, D.; Evans, M. J.; Boxhall, P.; Hamilton, J.; Stolle, C.; Wurl, O.; Ribas-Ribas, M.; Pereira, R.

2017-12-01

Oceanic dry deposition of atmospheric ozone (O3) is both the largest and most uncertain O3 depositional sink, and is widely acknowledged to be controlled largely by chemical reactions in the sea surface microlayer (SML) involving iodide (I-) and dissolved organic material (DOM). These reactions not only determine how quickly O3 can be removed from the atmosphere, but also result in emissions of trace gases including volatile organic compounds and may constitute a source of secondary organic aerosols to the marine atmosphere. Iodide concentrations at the sea surface vary by approximately an order of magnitude spatially, leading to more than fivefold variation in ozone deposition velocities (and volatile iodine fluxes). Sea-surface temperature is a reasonable predictor of [I-], however two recent parameterisations for surface I- differ by a factor of two at low latitudes. The nature and reactivity of marine DOM to O3 is almost completely unknown, although studies have suggested approximately equivalent chemical control of I- and DOM on ozone deposition. Here we present substantial new measurements of oceanic I- in both bulk seawater and the overlying SML, and show improved estimates of the global sea surface iodide distribution. We also present analyses of water-soluble DOM isolated from the SML and bulk seawater, and corresponding laboratory studies of ozone uptake to bulk and SML seawater, with the aim of characterizing the reactivity of O3 towards marine DOM.

Survey of bisphenol a diglycidyl ether (BADGE) in canned foods.

PubMed

Summerfield, W; Goodson, A; Cooper, I

1998-10-01

2,2-Bis(4-hydroxyphenyl)propane bis(2,3-epoxypropyl) ether (BADGE) is used in the manufacture of lacquers for coating the inside of food and beverage cans. In June 1996 the EC Scientific Committee for Food temporarily increased the specific migration limit applying to BADGE to 1 mg/kg pending consideration of additional toxicological data. In order to find out if there is migration of BADGE from can coatings into foods, a 'worst case' sampling exercise has been conducted to survey those canned foods where the propensity for migration of BADGE was judged to be highest. The foods surveyed include canned fish in oil, meat and milk and, altogether, BADGE was determined in 181 retail samples. Analysis for BADGE was conducted, in duplicate, by HPLC with fluorescence detection with confirmation of BADGE identity by GC/MS analysis using selected ion monitoring. BADGE was found at levels exceeding 1 mg/kg in seven of the 15 canned anchovy samples and five of the 22 sardine samples purchased during the period September 1995-July 1996. Infrared analysis of the can coatings provided strong evidence that the higher BADGE levels found were associated with use of PVC organosol lacquers, although in some cases cans coated with organosols gave low BADGE results. For canned sardine samples found to contain greater than 0.5 mg/kg BADGE in the total contents, a replicate can was opened and separate analyses performed on the drained fish and the oil. The results clearly showed that BADGE concentrations in the oil were about 20 times higher than in the drained fish. Further samples of canned sardines and anchovies were purchased in June/July 1997 and, in all cases, BADGE levels were found to be below 1 mg/kg. In the other retail canned foods, BADGE was not detectable (DL = 0.02 mg/kg) or detected at concentrations well below the temporary SML of 1 mg/kg.

Growth and characterization of InAs sub-monolayer quantum dots with varying fractional coverage

NASA Astrophysics Data System (ADS)

Mukherjee, S.; Pradhan, A.; Mukherje, S.; Maitra, T.; Sengupta, S.; Chakrabarti, S.; Nayak, A.; Bhunia, S.

2018-04-01

We have studied the optical properties of InAs sub monolayer (SML) quantum dots in GaAs quantum well with InAs average deposition below one monolayer (ML) [0.3 - 0.8 ML] in Molecular Beam Epitaxy (MBE) growth system. The samples have exhibited sharp photoluminescence peak at low temperature (3.3 K) which could be tuned in the near infrared (NIR) region (1.42 eV-1.47 eV) by controlling the InAs SML coverage.

Production of Antigens and Antibodies for Diagnosis of Arbovirus Diseases

DTIC Science & Technology

1994-05-20

ISS Phl-3 Vlsm2 7 314 VS-Indiana Indiana Lab sm9 5 271 VS-New Jersey Hazelhurst CEl8V4sml 4 364 Zika prototype smlSi 11 501 5 Additionally, 8 viruses ...residual infectivity was inactivated with beta-propiolactone. An additional 8 viruses were passaged in mice and the mice were stored frozen awaiting...beta- propiolactone. An additional 8 viruses were passaged in mice and the mice were stored frozen awaiting sucrose-acetone extraction of the brains

Supervised Machine-Learning-Based Determination of Three-Dimensional Structure of Metallic Nanoparticles

DOE PAGES

Timoshenko, Janis; Lu, Deyu; Lin, Yuewei; ...

2017-09-29

Tracking the structure of heterogeneous catalysts under operando conditions remains a challenge due to the paucity of experimental techniques that can provide atomic-level information for catalytic metal species. Here we report on the use of X-ray absorption near edge structure (XANES) spectroscopy and supervised machine learning (SML) for refining the three-dimensional geometry of metal catalysts. SML is used to unravel the hidden relationship between the XANES features and catalyst geometry. To train our SML method, we rely on ab-initio XANES simulations. Our approach allows one to solve the structure of a metal catalyst from its experimental XANES, as demonstrated heremore » by reconstructing the average size, shape and morphology of well-defined platinum nanoparticles. This method is applicable to the determination of the nanoparticle structure in operando studies and can be generalized to other nanoscale systems. In conclusion, it also allows on-the-fly XANES analysis, and is a promising approach for high-throughput and time-dependent studies.« less

Interplanetary Shocks Inducing Magnetospheric Supersubstorms (SML < ‑2500 nT): Unusual Auroral Morphologies and Energy Flow

NASA Astrophysics Data System (ADS)

Hajra, Rajkumar; Tsurutani, Bruce T.

2018-05-01

We present case studies of two interplanetary shock-induced supersubstorms (SSSs) with extremely high intensities (peak SML ‑4418 and ‑2668 nT) and long durations (∼1.7 and ∼3.1 hr). The events occurred on 2005 January 21 and 2010 April 5, respectively. It is shown that these SSSs have a different auroral evolution than a nominal Akasofu-type substorm. The auroras associated with the SSSs did not have the standard midnight onset and following expansion. Instead, at the time of the SML index peak, the midnight sector was generally devoid of intense auroras, while the most intense auroras were located in the premidnight and postmidnight magnetic local times. Precursor energy input through magnetic reconnection was insufficient to balance the large ionospheric energy dissipation during the SSSs. It is argued that besides the release of stored magnetotail energy during the SSSs, these were powered by additional direct driving through both dayside magnetic reconnection and solar wind ram energy.

Supervised Machine-Learning-Based Determination of Three-Dimensional Structure of Metallic Nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timoshenko, Janis; Lu, Deyu; Lin, Yuewei

Tracking the structure of heterogeneous catalysts under operando conditions remains a challenge due to the paucity of experimental techniques that can provide atomic-level information for catalytic metal species. Here we report on the use of X-ray absorption near edge structure (XANES) spectroscopy and supervised machine learning (SML) for refining the three-dimensional geometry of metal catalysts. SML is used to unravel the hidden relationship between the XANES features and catalyst geometry. To train our SML method, we rely on ab-initio XANES simulations. Our approach allows one to solve the structure of a metal catalyst from its experimental XANES, as demonstrated heremore » by reconstructing the average size, shape and morphology of well-defined platinum nanoparticles. This method is applicable to the determination of the nanoparticle structure in operando studies and can be generalized to other nanoscale systems. In conclusion, it also allows on-the-fly XANES analysis, and is a promising approach for high-throughput and time-dependent studies.« less

Color reduction of sulfonated eucalyptus kraft lignin.

PubMed

Zhang, Hui; Bai, Youcan; Zhou, Wanpeng; Chen, Fangeng

2017-04-01

Several eucalyptus lignins named as HSL, SML and BSL were prepared by high temperature sulfonation, sulfomethylation, butane sultone sulfonation respectively. The color properties of samples were investigated. Under optimized conditions the sulfonic group (SO 3 H) content of HSL, SML and BSL reached 1.52, 1.60 and 1.58mmol/g, respectively. Samples were characterized by UV-vis spectroscopy, FTIR spectroscopy, 1 H NMR spectroscopy, GPC and brightness test, respectively. The results revealed that BSL performed a higher molecular weight and lighter color due to the phenolic hydroxyl blocking by 1,4-butane sultone (1,4-BS). The color reduction of sodium borohydride treated BSL (labeled as SBSL) was further enhanced and the brightness value was improved by 76.1% compared with the darkest HSL. SBSL process was much better than HSL and SML process. Hydroxyl blocking effect of 1,4-BS and reducibility of sodium borohydride played important roles in the color reduction of sulfonated eucalyptus kraft lignin. Copyright © 2017 Elsevier B.V. All rights reserved.

Submesoscale-selective compensation of fronts in a salinity-stratified ocean.

PubMed

Spiro Jaeger, Gualtiero; Mahadevan, Amala

2018-02-01

Salinity, rather than temperature, is the leading influence on density in some regions of the world's upper oceans. In the Bay of Bengal, heavy monsoonal rains and runoff generate strong salinity gradients that define density fronts and stratification in the upper ~50 m. Ship-based observations made in winter reveal that fronts exist over a wide range of length scales, but at O(1)-km scales, horizontal salinity gradients are compensated by temperature to alleviate about half the cross-front density gradient. Using a process study ocean model, we show that scale-selective compensation occurs because of surface cooling. Submesoscale instabilities cause density fronts to slump, enhancing stratification along-front. Specifically for salinity fronts, the surface mixed layer (SML) shoals on the less saline side, correlating sea surface salinity (SSS) with SML depth at O(1)-km scales. When losing heat to the atmosphere, the shallower and less saline SML experiences a larger drop in temperature compared to the adjacent deeper SML on the salty side of the front, thus correlating sea surface temperature (SST) with SSS at the submesoscale. This compensation of submesoscale fronts can diminish their strength and thwart the forward cascade of energy to smaller scales. During winter, salinity fronts that are dynamically submesoscale experience larger temperature drops, appearing in satellite-derived SST as cold filaments. In freshwater-influenced regions, cold filaments can mark surface-trapped layers insulated from deeper nutrient-rich waters, unlike in other regions, where they indicate upwelling of nutrient-rich water and enhanced surface biological productivity.

Development of the Symbolic Manipulator Laboratory modeling package for the kinematic design and optimization of the Future Armor Rearm System robot. Ammunition Logistics Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

March-Leuba, S.; Jansen, J.F.; Kress, R.L.

1992-08-01

A new program package, Symbolic Manipulator Laboratory (SML), for the automatic generation of both kinematic and static manipulator models in symbolic form is presented. Critical design parameters may be identified and optimized using symbolic models as shown in the sample application presented for the Future Armor Rearm System (FARS) arm. The computer-aided development of the symbolic models yields equations with reduced numerical complexity. Important considerations have been placed on the closed form solutions simplification and on the user friendly operation. The main emphasis of this research is the development of a methodology which is implemented in a computer program capablemore » of generating symbolic kinematic and static forces models of manipulators. The fact that the models are obtained trigonometrically reduced is among the most significant results of this work and the most difficult to implement. Mathematica, a commercial program that allows symbolic manipulation, is used to implement the program package. SML is written such that the user can change any of the subroutines or create new ones easily. To assist the user, an on-line help has been written to make of SML a user friendly package. Some sample applications are presented. The design and optimization of the 5-degrees-of-freedom (DOF) FARS manipulator using SML is discussed. Finally, the kinematic and static models of two different 7-DOF manipulators are calculated symbolically.« less

Submesoscale-selective compensation of fronts in a salinity-stratified ocean

PubMed Central

Spiro Jaeger, Gualtiero; Mahadevan, Amala

2018-01-01

Salinity, rather than temperature, is the leading influence on density in some regions of the world’s upper oceans. In the Bay of Bengal, heavy monsoonal rains and runoff generate strong salinity gradients that define density fronts and stratification in the upper ~50 m. Ship-based observations made in winter reveal that fronts exist over a wide range of length scales, but at O(1)-km scales, horizontal salinity gradients are compensated by temperature to alleviate about half the cross-front density gradient. Using a process study ocean model, we show that scale-selective compensation occurs because of surface cooling. Submesoscale instabilities cause density fronts to slump, enhancing stratification along-front. Specifically for salinity fronts, the surface mixed layer (SML) shoals on the less saline side, correlating sea surface salinity (SSS) with SML depth at O(1)-km scales. When losing heat to the atmosphere, the shallower and less saline SML experiences a larger drop in temperature compared to the adjacent deeper SML on the salty side of the front, thus correlating sea surface temperature (SST) with SSS at the submesoscale. This compensation of submesoscale fronts can diminish their strength and thwart the forward cascade of energy to smaller scales. During winter, salinity fronts that are dynamically submesoscale experience larger temperature drops, appearing in satellite-derived SST as cold filaments. In freshwater-influenced regions, cold filaments can mark surface-trapped layers insulated from deeper nutrient-rich waters, unlike in other regions, where they indicate upwelling of nutrient-rich water and enhanced surface biological productivity. PMID:29507874

Two pulses of seasonal activity in martian southern mid-latitude recurring slope lineae (RSL)

NASA Astrophysics Data System (ADS)

Stillman, David E.; Grimm, Robert E.

2018-03-01

Recurring slope lineae (RSL) are narrow dark features that incrementally lengthen down steep low-albedo slopes when temperatures are warm, subsequently fade, and reoccur annually. RSL could be caused by wet, wet-triggered debris, or dry granular flow mechanisms. We have classified 190 candidate and confirmed southern mid-latitude (SML) RSL sites using six Mars years of high-resolution imagery to provide new constraints on RSL flow mechanisms. We demonstrate that at least three confirmed SML RSL sites have at least two pulses of active lengthening. We have also confirmed that RSL start much earlier than previously thought. The first SML RSL pulse occurs from solar longitude (Ls) 187° ± 6° to 226° ± 14° or 62 ± 32 sols, while the second pulse occurs from Ls 260° ± 26° to 329° ± 29° or 113 ± 89 sols. Even with the newly observed early pulse, the total SML RSL active duration is still shorter than RSL found elsewhere on the planet. No significant seasonal variations exist between the dominant (N, NW, W) slope-face orientations. The central peak of Hale crater appears to be anomalous in that it has a third pulse that rejuvenates RSL late in the southern summer (Ls 330° ± 1° to 348° ± 19° or 48 ± 26 sols). These additional RSL pulses of activity add increased complexity to RSL behavior. Follow-up missions may be needed to unambiguously discriminate between RSL mechanisms.

Depletion of Cellular Iron by Curcumin Leads to Alteration in Histone Acetylation and Degradation of Sml1p in Saccharomyces cerevisiae

PubMed Central

Azad, Gajendra Kumar; Singh, Vikash; Golla, Upendarrao; Tomar, Raghuvir S.

2013-01-01

Curcumin, a naturally occurring polyphenolic compound, is known to possess diverse pharmacological properties. There is a scarcity of literature documenting the exact mechanism by which curcumin modulates its biological effects. In the present study, we have used yeast as a model organism to dissect the mechanism underlying the action of curcumin. We found that the yeast mutants of histone proteins and chromatin modifying enzymes were sensitive to curcumin and further supplementation of iron resulted in reversal of the changes induced by curcumin. Additionally, treatment of curcumin caused the iron starvation induced expression of FET3, FRE1 genes. We also demonstrated that curcumin induces degradation of Sml1p, a ribonucleotide reductase inhibitor involved in regulating dNTPs production. The degradation of Sml1p was mediated through proteasome and vacuole dependent protein degradation pathways. Furthermore, curcumin exerts biological effect by altering global proteome profile without affecting chromatin architecture. These findings suggest that the medicinal properties of curcumin are largely contributed by its cumulative effect of iron starvation and epigenetic modifications. PMID:23520547

Respiratory Microbiome of Endangered Southern Resident Killer Whales and Microbiota of Surrounding Sea Surface Microlayer in the Eastern North Pacific.

PubMed

Raverty, Stephen A; Rhodes, Linda D; Zabek, Erin; Eshghi, Azad; Cameron, Caroline E; Hanson, M Bradley; Schroeder, J Pete

2017-03-24

In the Salish Sea, the endangered Southern Resident Killer Whale (SRKW) is a high trophic indicator of ecosystem health. Three major threats have been identified for this population: reduced prey availability, anthropogenic contaminants, and marine vessel disturbances. These perturbations can culminate in significant morbidity and mortality, usually associated with secondary infections that have a predilection to the respiratory system. To characterize the composition of the respiratory microbiota and identify recognized pathogens of SRKW, exhaled breath samples were collected between 2006-2009 and analyzed for bacteria, fungi and viruses using (1) culture-dependent, targeted PCR-based methodologies and (2) taxonomically broad, non-culture dependent PCR-based methodologies. Results were compared with sea surface microlayer (SML) samples to characterize the respective microbial constituents. An array of bacteria and fungi in breath and SML samples were identified, as well as microorganisms that exhibited resistance to multiple antimicrobial agents. The SML microbes and respiratory microbiota carry a pathogenic risk which we propose as an additional, fourth putative stressor (pathogens), which may adversely impact the endangered SRKW population.

Microbial Communities in the Surface Mucopolysaccharide Layer and the Black Band Microbial Mat of Black Band-Diseased Siderastrea siderea

PubMed Central

Sekar, Raju; Mills, DeEtta K.; Remily, Elizabeth R.; Voss, Joshua D.; Richardson, Laurie L.

2006-01-01

Microbial community profiles and species composition associated with two black band-diseased colonies of the coral Siderastrea siderea were studied by 16S rRNA-targeted gene cloning, sequencing, and amplicon-length heterogeneity PCR (LH-PCR). Bacterial communities associated with the surface mucopolysaccharide layer (SML) of apparently healthy tissues of the infected colonies, together with samples of the black band disease (BBD) infections, were analyzed using the same techniques for comparison. Gene sequences, ranging from 424 to 1,537 bp, were retrieved from all positive clones (n = 43 to 48) in each of the four clone libraries generated and used for comparative sequence analysis. In addition to LH-PCR community profiling, all of the clone sequences were aligned with LH-PCR primer sequences, and the theoretical lengths of the amplicons were determined. Results revealed that the community profiles were significantly different between BBD and SML samples. The SML samples were dominated by γ-proteobacteria (53 to 64%), followed by β-proteobacteria (18 to 21%) and α-proteobacteria (5 to 11%). In contrast, both BBD clone libraries were dominated by α-proteobacteria (58 to 87%), followed by verrucomicrobia (2 to 10%) and 0 to 6% each of δ-proteobacteria, bacteroidetes, firmicutes, and cyanobacteria. Alphaproteobacterial sequence types related to the bacteria associated with toxin-producing dinoflagellates were observed in BBD clone libraries but were not found in the SML libraries. Similarly, sequences affiliated with the family Desulfobacteraceae and toxin-producing cyanobacteria, both believed to be involved in BBD pathogenesis, were found only in BBD libraries. These data provide evidence for an association of numerous toxin-producing heterotrophic microorganisms with BBD of corals. PMID:16957217

Changes in optical characteristics of surface microlayers in the Peruvian upwelling region hint to photochemically and microbially-mediated DOM turnover

NASA Astrophysics Data System (ADS)

Engel, A.; Galgani, L.

2016-02-01

The coastal upwelling system off Peru is characterized by high biological activity and associated subsurface oxygen minimum zone, leading to an enhanced emission of atmospheric trace gases. High biological productivity in the water column may promote the establishment of enriched organic surface films, key environments for processes regulating gas fluxes across the water-air interface. During M91 cruise to the Peruvian upwelling, we focused our attention on the composition of the sea-surface microlayer (SML), the oceanic uppermost boundary directly subject to high solar radiation, often enriched in specific organic compounds of biological origin like Chromophoric Dissolved Organic Matter (CDOM) and marine gels. In the SML, the continuous photochemical and microbial recycling of organic matter may strongly influence gas exchange between marine systems and the atmosphere. In order to understand organic matter cycling in surface films, we analyzed SML and underlying water samples in 38 stations determining DOC concentrations, amino acids composition, marine gels, CDOM and bacterial abundance as indicators of photochemical and microbial alteration processes. CDOM composition was characterized by spectral slopes (S) values and Excitation-Emission Matrix fluorescence (EEMs), which allow to track changes in molecular weight (MW) of DOM, and to determine potential DOM sources. Profound changes in spectral slope properties were observed suggesting smaller MW CDOM in the SML compared to underlying water. Microbial and photochemical degradation are likely the main drivers for organic matter cycling in the top layer of the ocean. Consequences on the formation of inorganic and organic species highly relevant for air-sea gas exchange and for climate dynamics will be discussed.

Antibacterial Activity of Marine and Black Band Disease Cyanobacteria against Coral-Associated Bacteria

PubMed Central

Gantar, Miroslav; Kaczmarsky, Longin T.; Stanić, Dina; Miller, Aaron W.; Richardson, Laurie L.

2011-01-01

Black band disease (BBD) of corals is a cyanobacteria-dominated polymicrobial disease that contains diverse populations of heterotrophic bacteria. It is one of the most destructive of coral diseases and is found globally on tropical and sub-tropical reefs. We assessed ten strains of BBD cyanobacteria, and ten strains of cyanobacteria isolated from other marine sources, for their antibacterial effect on growth of heterotrophic bacteria isolated from BBD, from the surface mucopolysaccharide layer (SML) of healthy corals, and three known bacterial coral pathogens. Assays were conducted using two methods: co-cultivation of cyanobacterial and bacterial isolates, and exposure of test bacteria to (hydrophilic and lipophilic) cyanobacterial cell extracts. During co-cultivation, 15 of the 20 cyanobacterial strains tested had antibacterial activity against at least one of the test bacterial strains. Inhibition was significantly higher for BBD cyanobacteria when compared to other marine cyanobacteria. Lipophilic extracts were more active than co-cultivation (extracts of 18 of the 20 strains were active) while hydrophilic extracts had very limited activity. In some cases co-cultivation resulted in stimulation of BBD and SML bacterial growth. Our results suggest that BBD cyanobacteria are involved in structuring the complex polymicrobial BBD microbial community by production of antimicrobial compounds. PMID:22073011

Research on the industry environmental total factor productivity in Jiangsu Province based on the SBM-SML

NASA Astrophysics Data System (ADS)

Lingfang, Sun; Han, Wang; Jian, Gong

2017-03-01

This paper uses the SBM-SML to measure the industry environmental total factor productivity in Jiangsu province of its 13 cities during 2005-2014 with SO2 emissions as the undesirable output, and discomposes the total factor productivity into the pure technical efficiency, the scale efficiency change, the pure technical change and the scale technical change. The research shows that the overall trend of the industry environmental total factor productivity is increasing in Jiangsu province during 2005-2014, the technical change is a main reason pushing up growth rates of economy, and the pure technical change is the intrinsic motivation of the technical change.Introduction.

Regulation of Small Mitochondrial DNA Replicative Advantage by Ribonucleotide Reductase in Saccharomyces cerevisiae

PubMed Central

Bradshaw, Elliot; Yoshida, Minoru; Ling, Feng

2017-01-01

Small mitochondrial genomes can behave as selfish elements by displacing wild-type genomes regardless of their detriment to the host organism. In the budding yeast Saccharomyces cerevisiae, small hypersuppressive mtDNA transiently coexist with wild-type in a state of heteroplasmy, wherein the replicative advantage of the small mtDNA outcompetes wild-type and produces offspring without respiratory capacity in >95% of colonies. The cytosolic enzyme ribonucleotide reductase (RNR) catalyzes the rate-limiting step in dNTP synthesis and its inhibition has been correlated with increased petite colony formation, reflecting loss of respiratory function. Here, we used heteroplasmic diploids containing wild-type (rho+) and suppressive (rho−) or hypersuppressive (HS rho−) mitochondrial genomes to explore the effects of RNR activity on mtDNA heteroplasmy in offspring. We found that the proportion of rho+ offspring was significantly increased by RNR overexpression or deletion of its inhibitor, SML1, while reducing RNR activity via SML1 overexpression produced the opposite effects. In addition, using Ex Taq and KOD Dash polymerases, we observed a replicative advantage for small over large template DNA in vitro, but only at low dNTP concentrations. These results suggest that dNTP insufficiency contributes to the replicative advantage of small mtDNA over wild-type and cytosolic dNTP synthesis by RNR is an important regulator of heteroplasmy involving small mtDNA molecules in yeast. PMID:28717049

Quorum Sensing Signal Production and Microbial Interactions in a Polymicrobial Disease of Corals and the Coral Surface Mucopolysaccharide Layer

PubMed Central

Zimmer, Beth L.; May, Amanda L.; Bhedi, Chinmayee D.; Dearth, Stephen P.; Prevatte, Carson W.; Pratte, Zoe; Campagna, Shawn R.; Richardson, Laurie L.

2014-01-01

Black band disease (BBD) of corals is a complex polymicrobial disease considered to be a threat to coral reef health, as it can lead to mortality of massive reef-building corals. The BBD community is dominated by gliding, filamentous cyanobacteria with a highly diverse population of heterotrophic bacteria. Microbial interactions such as quorum sensing (QS) and antimicrobial production may be involved in BBD disease pathogenesis. In this study, BBD (whole community) samples, as well as 199 bacterial isolates from BBD, the surface mucopolysaccharide layer (SML) of apparently healthy corals, and SML of apparently healthy areas of BBD-infected corals were screened for the production of acyl homoserine lactones (AHLs) and for autoinducer-2 (AI-2) activity using three bacterial reporter strains. AHLs were detected in all BBD (intact community) samples tested and in cultures of 5.5% of BBD bacterial isolates. Over half of a subset (153) of the isolates were positive for AI-2 activity. AHL-producing isolates were further analyzed using LC-MS/MS to determine AHL chemical structure and the concentration of (S)-4,5-dihydroxy-2,3-pentanedione (DPD), the biosynthetic precursor of AI-2. C6-HSL was the most common AHL variant detected, followed by 3OC4-HSL. In addition to QS assays, 342 growth challenges were conducted among a subset of the isolates, with 27% of isolates eliciting growth inhibition and 2% growth stimulation. 24% of BBD isolates elicited growth inhibition as compared to 26% and 32% of the bacteria from the two SML sources. With one exception, only isolates that exhibited AI-2 activity or produced DPD inhibited growth of test strains. These findings demonstrate for the first time that AHLs are present in an active coral disease. It is possible that AI-2 production among BBD and coral SML bacteria may structure the microbial communities of both a polymicrobial infection and the healthy coral microbiome. PMID:25268348

Biogeochemical linkage between atmosphere and ocean in the eastern equatorial Pacific Ocean: Results from the EqPOS research cruise

NASA Astrophysics Data System (ADS)

Furutani, H.; Inai, Y.; Aoki, S.; Honda, H.; Omori, Y.; Tanimoto, H.; Iwata, T.; Ueda, S.; Miura, K.; Uematsu, M.

2012-12-01

Eastern equatorial Pacific Ocean is a unique oceanic region from several biogeochemical points of view. It is a remote open ocean with relatively high marine biological activity, which would result in limited influence of human activity but enhanced effect of marine natural processes on atmospheric composition. It is also characterized as high nutrient low chlorophyll (HNLC) ocean, in which availability of trace metals such as iron and zinc limits marine primary production and thus atmospheric deposition of these trace elements to the ocean surface is expected to play an important role in regulating marine primary production and defining unique microbial community. High sea surface temperature in the region generates strong vertical air convection which efficiently brings tropospheric atmospheric composition into stratosphere. In this unique eastern equatorial Pacific Ocean, EqPOS (Equatorial Pacific Ocean and Stratospheric/Tropospheric Atmospheric Study) research cruise was organized as a part of SOLAS Japan activity to understand biogeochemical ocean-atmospheric interaction in the region. Coordinated atmospheric, oceanic, and marine biological observations including sampling/characterization of thin air-sea interfacial layer (sea surface microlayer: SML) and launching large stratospheric air sampling balloons were carried out on-board R/V Hakuho Maru starting from 29 January for 39 days. Biogeochemically important trace/long-lived gases such as CO2, dimethyl sulfide (DMS), and some volatile organic carbons (VOCs) both in the atmosphere and seawater were continuously monitored and their air-sea fluxes were also observed using gradient and eddy-covariance techniques. Atmospheric gas measurement of CO2, CH4, N2O, SF6, CO, H2, Ar and isotopic composition of selected gases were further extended to stratospheric air by balloon-born sampling in addition to a vertical profiling of O3, CO2, and H2O with sounding sondes. Physical and chemical properties of marine atmospheric aerosols such as size distribution, total and cloud condensation nuclei concentrations, particle morphology, bulk and single particle chemical composition were also continuously determined to find out potential link between biogenic VOCs emitted from the ocean and aerosol composition. Biological and biogeochemical characterizations of marine microorganisms, suspended particulate matter, dissolved nutrients in seawater and SML were also conducted. In the presentation, brief overview of the research activities during the EqPOS cruise and biogeochemical linkage atmosphere and ocean via atmospheric and oceanic gaseous and particulate matter from ocean surface to stratosphere observed during the cruise and unique importance of SML would be presented.

Study on detection of terrestrial and marine fractions in marine organic molecules by spectrophoto- and spectrofluorometric methods

NASA Astrophysics Data System (ADS)

Drozdowska, Violetta; Wróbel, Iwona; Piskozub, Jacek

2017-04-01

The sea surface is a highly productive and active interface between the sea and the atmosphere. Sea surface films are created by organic matter from sea and land sources and they dissipate due to loss of material at the sea surface, including microbial degradation, chemical and photo chemical processes, and loss due to absorption and adsorption onto particulates. However the surface microlayer is almost ubiquitous and cover most of the surface of the ocean, even under conditions of high turbulence. Surface active molecules (surfactants) present in the surface microlayer (SML) may modify the number of physical processes taking place there: among others they affect the depth of penetration of solar radiation and gas exchange. Therefore, research on the influence of surfactants on the sea surface properties become an important task, especially in coastal waters and in vicinity of the river mouths. Surfactants comprises a mixture of organic molecules rich in lipids, polymeric and humus whose proportions determine the various properties of the SML. A unique structure of the energy levels of the organic molecules results in a unique spectral distribution of the light intensity absorbed and emitted by the molecules. Hence, the absorption and fluorescence spectra of organic compounds may allow the identification of the sources of organic matter. Additionally, several absorption (E2:E3, S, SR) and fluorescence (fluorescence intensities at peaks: A, C, M, T, the ratio (M+T)/(A+C), HIX) indices help in describing the changes in molecular size and weight as well as composition of organic matter during the humification processes and caused by photobleaching and biodegradation. Investigations included the region of Gulf of Gdańsk, along a transect from the Vistula River outlet to open sea. The fluorescence and absorption measurements of the samples collected from a surface films and a subsurface layer (SS, a depth of 1 m) during three research cruises in Gulf of Gdańsk, the Baltic Sea, as well as hydrophysical studies and meteorological observations allowed to assess (i) the contribution of two terrestrial components (A and C) decreased with increasing salinity ( 1.64% and 1.89 % in SML and 0.78 and 0.71 % in SS, respectively), while the contribution of, in-situ, in the sea produced components (M and T) increased with salinity ( 0.52% and 2.83% in SML and 0.98% and 1.87 % in SS, respectively), (ii) the biggest relative changes of the FDOM component composition, along the transect from the Vistula River outlet to Gdańsk Deep, were recorded for component T, both in SML and SS (about 18.5 % and 12.3 %, respectively), (iii) the ratio E2:E3 points to discrete changes in molecular weight/size, effected by photobleaching, while (iv) HIX index reflects the humification/condensation processes more sensitively and effectively in SS. The organic molecules included in the SML can specifically modify the physical processes associated with the sea surface microlayers. It should be necessary to continue a study on the physical properties of surface microlayer in the future, especially in less urbanized and more natural and pristine region, like Arctic.

Fabrication and evaluation of magnetic activated carbon as adsorbent for ultrasonic assisted magnetic solid phase dispersive extraction of bisphenol A from milk prior to high performance liquid chromatographic analysis with ultraviolet detection.

PubMed

Filippou, Olga; Deliyanni, Eleni A; Samanidou, Victoria F

2017-01-06

In the present study, the impregnation of a micro - meso porous activated carbon with magnetite (Fe 3 O 4 ) was successfully achieved by sonication and the magnetic activated carbon prepared (Bmi) was evaluated as a new adsorbent for ultrasonic assisted magnetic solid phase dispersive extraction of Bisphenol A (BPA) from cow milk and human breast milk samples, prior to the determination by HPLC with UV detection. The prepared Bmi was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The effect of pH on adsorption, initial concentration, contact time and desorption were studied. The main experimental parameters influencing extraction efficiency of BPA, such as type and amount of the adsorbent, sample amount, type of desorption solvent, time of adsorption and desorption, type of precipitation solvent, were investigated and optimized. Under the optimal extraction conditions the absolute recovery of BPA was 81% and 95% in cow milk and human breast milk samples, respectively. Good linearity was observed in the investigated concentration range of 2.5μgkg -1 -5000μgkg -1 (R 2 =0.9997). Limit of detection (LOD) was 0.75μgL -1 , which is in accordance with the specific migration limit (SML) established by the European Union, and limit of quantification (LOQ) was 2.5μgL -1 . Within-day and between-day recoveries ranged from 91.4% to 98.6% and 89.1% to 99.4% respectively and the RSDs were less than 3.7%. Due to the excellent magnetic behavior of Bmi the proposed method was shown to be simple and rapid. Besides these, this method is sensitive, low cost, efficient and environmentally friendly. Copyright © 2016 Elsevier B.V. All rights reserved.

Ranking and combining multiple predictors without labeled data

PubMed Central

Parisi, Fabio; Strino, Francesco; Nadler, Boaz; Kluger, Yuval

2014-01-01

In a broad range of classification and decision-making problems, one is given the advice or predictions of several classifiers, of unknown reliability, over multiple questions or queries. This scenario is different from the standard supervised setting, where each classifier’s accuracy can be assessed using available labeled data, and raises two questions: Given only the predictions of several classifiers over a large set of unlabeled test data, is it possible to (i) reliably rank them and (ii) construct a metaclassifier more accurate than most classifiers in the ensemble? Here we present a spectral approach to address these questions. First, assuming conditional independence between classifiers, we show that the off-diagonal entries of their covariance matrix correspond to a rank-one matrix. Moreover, the classifiers can be ranked using the leading eigenvector of this covariance matrix, because its entries are proportional to their balanced accuracies. Second, via a linear approximation to the maximum likelihood estimator, we derive the Spectral Meta-Learner (SML), an unsupervised ensemble classifier whose weights are equal to these eigenvector entries. On both simulated and real data, SML typically achieves a higher accuracy than most classifiers in the ensemble and can provide a better starting point than majority voting for estimating the maximum likelihood solution. Furthermore, SML is robust to the presence of small malicious groups of classifiers designed to veer the ensemble prediction away from the (unknown) ground truth. PMID:24474744

A comparison of hand grasp breakaway strengths and bare-handed grip strengths of the astronauts, SML 3 test subjects, and the subjects from the general population

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar L.; Klute, Glenn K.

1993-01-01

Astronauts have the task of retrieving and deploying satellites and handling massive objects in a around the payload bay. Concerns were raised that manual handling of such massive objects might induce loads to the shuttle suits exceeding the design-certified loads. The Crew and Thermal Division of NASA JSC simulated the satellite handling tasks (Satellite Manload Tests 1 and 3) and determined the maximum possible load that a suited member could impart onto the suit. In addition, the tests revealed that the load to the suit by an astronaut could be calculated from the astronaut's maximum hand grasp breakaway strength. Thus, this study was conducted to document that hand grasp breakaway strengths of the astronauts who were scheduled to perform EVA during the upcoming missions. In addition, this study verified whether the SML 3 test results were sufficient for documenting the maximum possible load. An attempt was made to predict grasp strength from grip strength and hand anthropometry. Based on the results from this study, the SML 3 test results were deemed sufficient to document the maximum possible load on the suit. Finally, prediction of grasp strength from grip strength was not as accurate as expected. Hence, it was recommended that grasp strength be collected from the astronauts in order to obtain accurate load estimation.

Synchronous neural interactions assessed by magnetoencephalography: a functional biomarker for brain disorders

NASA Astrophysics Data System (ADS)

Georgopoulos, Apostolos P.; Karageorgiou, Elissaios; Leuthold, Arthur C.; Lewis, Scott M.; Lynch, Joshua K.; Alonso, Aurelio A.; Aslam, Zaheer; Carpenter, Adam F.; Georgopoulos, Angeliki; Hemmy, Laura S.; Koutlas, Ioannis G.; Langheim, Frederick J. P.; Riley McCarten, J.; McPherson, Susan E.; Pardo, José V.; Pardo, Patricia J.; Parry, Gareth J.; Rottunda, Susan J.; Segal, Barbara M.; Sponheim, Scott R.; Stanwyck, John J.; Stephane, Massoud; Westermeyer, Joseph J.

2007-12-01

We report on a test to assess the dynamic brain function at high temporal resolution using magnetoencephalography (MEG). The essence of the test is the measurement of the dynamic synchronous neural interactions, an essential aspect of the brain function. MEG signals were recorded from 248 axial gradiometers while 142 human subjects fixated a spot of light for 45-60 s. After fitting an autoregressive integrative moving average (ARIMA) model and taking the stationary residuals, all pairwise, zero-lag, partial cross-correlations (PCCij0) and their z-transforms (zij0) between i and j sensors were calculated, providing estimates of the strength and sign (positive, negative) of direct synchronous coupling at 1 ms temporal resolution. We found that subsets of zij0 successfully classified individual subjects to their respective groups (multiple sclerosis, Alzheimer's disease, schizophrenia, Sjögren's syndrome, chronic alcoholism, facial pain, healthy controls) and gave excellent external cross-validation results. Contribution by the authors: Designed research (APG); acquired data (AAA, IGK, FJPL, ACL, SML, JJS); analyzed data (APG, EK, ACL, JKL); wrote the paper (APG, EK, ACL, SML); contributed subjects (AAA, ZA, AFC, AG, LSH, IGK, FJPL, SML, JRM, SEM, JVP, PJP, GJP, SJR, BMS, SRS, MS, JJS, JJW); discussed results (All); contributed equally (ZA, AFC, AG, LSH, FJPL, JRM, SEM, JVP, PJP, GJP, SJR, BMS, SRS, MS, JJS, JJW).

Growth and stability of Langmuir-Blodgett films on OH-, H-, or Br-terminated Si(001)

NASA Astrophysics Data System (ADS)

Bal, J. K.; Kundu, S.; Hazra, S.

2010-01-01

Growth of Langmuir-Blodgett (LB) films of nickel arachidate (NiA) on differently terminated (OH-, H-, or Br-terminated) Si(001) substrates and their structural evolution with time have been investigated by x-ray reflectivity technique and complemented by atomic force microscopy. Stable and strongly attached asymmetric monolayer (AML) of NiA is found to grow on freshly prepared oxide-covered Si substrate while unstable and weakly attached symmetric monolayer (SML) of NiA grows on H-terminated Si substrate, corresponding to stable hydrophilic and unstable hydrophobic natures of the substrates, respectively. The structure of LB film on Br-terminated Si substrate, however, shows intermediate behavior, namely, both AML and SML are present on the substrate, indicative of coexisting (hydrophilic and hydrophobic) nature of this terminated surface. Such coexisting nature of the substrate shows unusual growth behavior of LB films: (i) hydrophilic and hydrophobic attachments of NiA molecules in single up stroke of deposition and (ii) growth of few ring-shaped large-heights islands in subsequent deposition. These probably occur due to the presence of substrate-induced perturbation in the Langmuir monolayer and release of initially accumulated strain in the film structures near hydrophilic/hydrophobic interface, respectively, and provide the possibility to grow desired structures (AML or SML) of LB films by passivation-selective surface engineering.

The Relieving Effects of BrainPower Advanced, a Dietary Supplement, in Older Adults with Subjective Memory Complaints: A Randomized, Double-Blind, Placebo-Controlled Trial.

PubMed

Zhu, Jingfen; Shi, Rong; Chen, Su; Dai, Lihua; Shen, Tian; Feng, Yi; Gu, Pingping; Shariff, Mina; Nguyen, Tuong; Ye, Yeats; Rao, Jianyu; Xing, Guoqiang

2016-01-01

Subjective memory complaints (SMCs) are common in older adults that can often predict further cognitive impairment. No proven effective agents are available for SMCs. The effect of BrainPower Advanced, a dietary supplement consisting of herbal extracts, nutrients, and vitamins, was evaluated in 98 volunteers with SMCs, averaging 67 years of age (47-88), in a randomized, double-blind, placebo-controlled trial. Subjective hypomnesis/memory loss (SML) and attention/concentration deficits (SAD) were evaluated before and after 12-week supplementation of BrainPower Advanced capsules (n = 47) or placebo (n = 51), using a 5-point memory questionnaire (1 = no/slight, 5 = severe). Objective memory function was evaluated using 3 subtests of visual/audio memory, abstraction, and memory recall that gave a combined total score. The BrainPower Advanced group had more cases of severe SML (severity ⩾ 3) (44/47) and severe SAD (43/47) than the placebo group (39/51 and 37/51, < 0.05, < 0.05, resp.) before the treatment. BrainPower Advanced intervention, however, improved a greater proportion of the severe SML (29.5%)(13/44) (P < 0.01) and SAD (34.9%)(15/43)(P < 0.01) than placebo (5.1% (2/39) and 13.5% (5/37), resp.). Thus, 3-month BrainPower Advanced supplementation appears to be beneficial to older adults with SMCs.

Compressive strength evolution of thermally-stressed Saint Maximin limestone.

NASA Astrophysics Data System (ADS)

Farquharson, J.; Griffiths, L.; Baud, P.; Wadsworth, F. B.; Heap, M. J.

2017-12-01

The Saint Maximin quarry (Oise, France) opened in the early 1600s, and its limestone has been used extensively as masonry stone, particularly during the classical era of Parisian architecture from the 17th century onwards. Its widespread use has been due to a combination of its regional availability, its high workability, and its aesthetic appeal. Notable buildings completed using this material include sections of the Place de la Concorde and the Louvre in Paris. More recently, however, it has seen increasing use in the construction of large private residences throughout the United States as well as extensions to private institutions such as Stanford University. For any large building, fire hazard can be a substantial concern, especially in tectonically active areas where catastrophic fires may arise following large-magnitude earthquakes. Typically, house fires burn at temperatures of around 600 °C ( 1000 F). Given the ubiquity of this geomaterial as a building stone, it is important to ascertain the influence of heating on the strength of Saint Maximin limestone (SML), and in turn the structural stability of the buildings it is used in. We performed a series of compressive tests and permeability measurements on samples of SML to determine its strength evolution in response to heating to incrementally higher temperatures. We observe that the uniaxial compressive strength of SML decreases from >12 MPa at room temperature to <7 MPa at 600 °C. The rate of strength reduction increases at elevated temperature (>400 °C). We anticipate that this substantial weakening is in part a result of thermal microcracking, whereby changes in temperature induce thermal stresses due to a mismatch in thermal expansion between the constituent grains. This mechanism is compounded by the volumetric increase of quartz through its alpha - beta transition at 573 °C, and by the thermal decomposition of calcite. To track the formation of thermal microcracks, we monitor acoustic emissions, a common proxy for microcracking, during the heating of an SML sample. The implications of these results are that in the event of a fire, the structural integrity of buildings constructed using Saint Maximin limestone could be greatly compromised. Its ubiquity as a masonry stone demands consideration during fire hazard mitigation.

Anthropogenic impact in the Santa Maria di Leuca cold-water coral province (Mediterranean Sea): Observations and conservation straits

NASA Astrophysics Data System (ADS)

D'Onghia, G.; Calculli, C.; Capezzuto, F.; Carlucci, R.; Carluccio, A.; Grehan, A.; Indennidate, A.; Maiorano, P.; Mastrototaro, F.; Pollice, A.; Russo, T.; Savini, A.; Sion, L.; Tursi, A.

2017-11-01

The Santa Maria di Leuca (SML) cold-water coral (CWC) province is a proposed priority conservation area according to several conservation initiatives in the Mediterranean Sea. Part of it is a Fisheries Restricted Area (FRA). Anthropogenic impacts due to fishing on this FRA were investigated using a towed camera system during 2005. The geographic distribution of fishing effort in the SML CWC province was examined through an observers' program of longline and trawl fishing activities during 2009 and 2010 and Vessel Monitoring by satellite System (VMS) data from 2008 to 2013. Using the video system, it was possible to observe evidence of impacts in the FRA due to longlines, proved by remains of lines on the bottoms and/or entangled in corals, and those due to trawl nets, proved by trawl door scars on the bottom. The application of Generalized Liner Models indicates that the impacts due to longline were significantly related to a geographic site characterized by carbonate mounds while those from trawl net were significantly related to the soft bottoms, consisting of bioturbated fine-grained sediments. The presence of waste of various types was also observed in the FRA; plastic was the most widespread waste and was significantly related to a macrohabitat characterized by the presence of corals. The geographic distribution of fishing effort for each type of fishing were rather superimposed in the two years of the observers' program and six years of VMS data with a significantly greater fishing effort outside the FRA than inside this area. The trawlers generally fished on the muddy bottoms of the upper and middle slope within the SML CWC province and near and inside the northward limit of the FRA. The longliners fished mainly on the shelf in north and off the FRA. The coral by-catch was only recorded during 2009 in 26% of the trawl hauls. No coral by-catch was recorded from longlining in either year. The catches from longlining mainly consisted of Chelidonichthys lucerna, Merluccius merluccius and Conger conger while those from trawling mostly consisted of Aristeus antennatus, Aristaeomorpha foliacea and M. merluccius. The information collected during the observers' program and VMS data indicated greater impact due to trawling than longlining. The conservation and effective management of this vulnerable marine ecosystem remain difficult.

Spin-memory loss due to spin-orbit coupling at ferromagnet/heavy-metal interfaces: Ab initio spin-density matrix approach

NASA Astrophysics Data System (ADS)

Dolui, Kapildeb; Nikolić, Branislav K.

2017-12-01

Spin-memory loss (SML) of electrons traversing ferromagnetic-metal/heavy-metal (FM/HM), FM/normal-metal (FM/NM), and HM/NM interfaces is a fundamental phenomenon that must be invoked to explain consistently large numbers of spintronic experiments. However, its strength extracted by fitting experimental data to phenomenological semiclassical theory, which replaces each interface by a fictitious bulk diffusive layer, is poorly understood from a microscopic quantum framework and/or materials properties. Here we describe an ensemble of flowing spin quantum states using spin-density matrix, so that SML is measured like any decoherence process by the decay of its off-diagonal elements or, equivalently, by the reduction of the magnitude of polarization vector. By combining this framework with density functional theory, we examine how all three components of the polarization vector change at Co/Ta, Co/Pt, Co/Cu, Pt/Cu, and Pt/Au interfaces embedded within Cu/FM/HM/Cu vertical heterostructures. In addition, we use ab initio Green's functions to compute spectral functions and spin textures over FM, HM, and NM monolayers around these interfaces which quantify interfacial spin-orbit coupling and explain the microscopic origin of SML in long-standing puzzles, such as why it is nonzero at the Co/Cu interface; why it is very large at the Pt/Cu interface; and why it occurs even in the absence of disorder, intermixing and magnons at the interface.

Improving the detection of tectonic transients in Japan by accounting for Earth's deformation response to surface mass loading

NASA Astrophysics Data System (ADS)

Martens, H. R.; Simons, M.; Moore, A. W.; Owen, S. E.; Rivera, L. A.

2016-12-01

We explore the contributions of oceanic, atmospheric, and hydrologic mass loading to Global Navigation Satellite System (GNSS)-inferred observations of surface displacements in Japan. Surface mass loading (SML) generates mm- to cm-level deformation of the solid Earth on time scales of hours to years, which exceeds the measurement uncertainties of most GNSS position estimates. By improving the efficiency and accuracy of the prediction and empirical estimation of SML response, we aim to reduce the variance of GNSS time series and therefore enhance the ability to resolve subtle tectonic signals, such as aseismic transients associated with subduction zone processes. Using the GIPSY software in precise point positioning mode, we estimate time series of sub-daily receiver positions for the GNSS Earth Observation Network System (GEONET) in Japan. We also model the Earth's elastic deformation response to a variety of surface mass loads, including loads of atmospheric (e.g., ECMWF) and oceanic (e.g., TPXO8-Atlas, ECCO2) origin. We extract periodic signals, such as the ocean tides and seasonal variations in hydrological loading, using harmonic analysis. Deformation caused by non-periodic loads, such as non-tidal oceanic and atmospheric loads, can be predicted and removed to further reduce the variance. We seek to streamline the workflow for estimating SML-induced surface displacements from a variety of sources in order to account for loading signals in routine GNSS data processing, thereby improving the ability to assess the mechanics of plate boundaries.

Development of potential novel cushioning agents for the compaction of coated multi-particulates by co-processing micronized lactose with polymers.

PubMed

Lin, Xiao; Chyi, Chin Wun; Ruan, Ke-feng; Feng, Yi; Heng, Paul Wan Sia

2011-10-01

This work aimed to explore the potential of lactose as novel cushioning agents with suitable physicomechanical properties by micronization and co-spray drying with polymers for protecting coated multi-particulates from rupture when they are compressed into tablets. Several commercially available lactose grades, micronized lactose (ML) produced by jet milling, spray-dried ML (SML), and polymer-co-processed SMLs, were evaluated for their material characteristics and tableting properties. Hydroxypropylcellulose (HPC), hydroxypropylmethylcellulose (HPMC), and polyvinylpyrrolidone (PVP) at three different levels were evaluated as co-processed polymers for spray drying. Sugar multi-particulates layered with chlorpheniramine maleate followed by an ethylcellulose coat were tableted using various lactose types as fillers. Drug release from compacted multi-particulate tablets was used to evaluate the cushioning effect of the fillers. The results showed that the cushioning effect of lactose principally depended on its particle size. Micronization can effectively enhance the protective action of lactose. Although spray drying led to a small reduction in the cushioning effect of ML, it significantly improved the physicomechanical properties of ML. Co-spray drying with suitable polymers improved both the cushioning effect and the physicomechanical properties of SML to a certain degree. Among the three polymers studied, HPC was the most effective in terms of enhancing the cushioning effect of SML. This was achieved by reducing yield pressure, and enhancing compressibility and compactibility. The combination of micronization and co-spray drying with polymers is a promising method with which new applications for lactose can be developed. Copyright © 2011 Elsevier B.V. All rights reserved.

Somatic mutation load of estrogen receptor-positive breast tumors predicts overall survival: an analysis of genome sequence data.

PubMed

Haricharan, Svasti; Bainbridge, Matthew N; Scheet, Paul; Brown, Powel H

2014-07-01

Breast cancer is one of the most commonly diagnosed cancers in women. While there are several effective therapies for breast cancer and important single gene prognostic/predictive markers, more than 40,000 women die from this disease every year. The increasing availability of large-scale genomic datasets provides opportunities for identifying factors that influence breast cancer survival in smaller, well-defined subsets. The purpose of this study was to investigate the genomic landscape of various breast cancer subtypes and its potential associations with clinical outcomes. We used statistical analysis of sequence data generated by the Cancer Genome Atlas initiative including somatic mutation load (SML) analysis, Kaplan-Meier survival curves, gene mutational frequency, and mutational enrichment evaluation to study the genomic landscape of breast cancer. We show that ER(+), but not ER(-), tumors with high SML associate with poor overall survival (HR = 2.02). Further, these high mutation load tumors are enriched for coincident mutations in both DNA damage repair and ER signature genes. While it is known that somatic mutations in specific genes affect breast cancer survival, this study is the first to identify that SML may constitute an important global signature for a subset of ER(+) tumors prone to high mortality. Moreover, although somatic mutations in individual DNA damage genes affect clinical outcome, our results indicate that coincident mutations in DNA damage response and signature ER genes may prove more informative for ER(+) breast cancer survival. Next generation sequencing may prove an essential tool for identifying pathways underlying poor outcomes and for tailoring therapeutic strategies.

Physicochemical signatures of natural surfactant sea films from coastal Middle Adriatic stations

NASA Astrophysics Data System (ADS)

Frka, Sanja; Pogorzelski, Stanislaw; Kozarac, Zlatica; Ćosović, Božena

2013-04-01

Boundary layers between different environmental compartments represent critical interfaces for biological, chemical and physical processes. The sea surface microlayer (SSM) as a top layer of the sea surface represents natural interface between the atmosphere and ocean. Although < 1 mm in thickness the SML plays a key role in the global biogeochemical cycling because all gaseous, liquid and particulate materials must pass through this interface when exchanging between the ocean and the atmosphere. The SSM thus represents a very important driver enhancing air-water exchange processes. A variety of natural and anthropogenic organic compounds, particularly those which are surface active (SA) are generally enriched in the SML. It is widely acknowledged that the SSM is complex matrix of SA organics as carbohydrates, proteins, lipids and humic substances. Although lipid material is much less abundant than carbohydrates and proteins in the SML, their contribution to surface activity may be disproportionately large. The surfactant films at the air-sea interface change its physicochemical properties reducing air-sea exchange possesses by impeding molecular diffusion across the interface and influencing the hydrodynamic characteristics of water motion at the interface. Various biological, chemical and physical processes lead to the alteration of the film chemical composition, surface physical properties, surface concentration and spatial distribution of film-forming components. Instead of analyzing its chemical composition, it should be possible to scale the SML surface pressure-area (π-A) isotherms in terms of structural parameters which appear to be a sensitive and quantitative measure of the film physicochemical composition, surface concentration and miscibility of its film-forming components. We will present a large data set obtained by electrochemical and monolayer techniques, accompanied with the novel scaling approach for physicochemical characterization of SA substances of the natural microlayers from coastal Middle Adriatic stations including saline Rogoznica Lake and Krka river estuarine station. Higher primary production during late spring-early autumn is reflected in the presence of microlayers of higher surfactant activity containing on average molecules of lower molecular masses (Mw=0.65±0.27 kDa) and higher miscibility (y=6.46±1.33) and elasticity (E=18.33±2.02 mN/m) modulus in comparison to structural parameters (average Mw=2.15±1.58 kDa; y=3.51±1.46; E=6.41±1.97 mN/m) obtained for microlayers from period of lower organic matter production. Higher inhibition effect on the reduction process of cadmium ions is observed for natural microlayers abundant with SA material from more productive period. This kind of distribution is explained as the consequence of competitive adsorption of hydrophobic lipid-like substances of lower Mw which highly influence the surface structural properties of natural air-water interface forming there segregated surface films during more productive period. This study will offer different perspective on contemporary SML concept taking into account the lipids that act as end-members highly influencing seasonal change of SA concentration and surface structural properties of natural films at the air-water interface.

Wireless LAN Extension

DTIC Science & Technology

2003-03-01

competing for airspace in the 2.4GHz radio spectrum. Most of these devices are actually common household products like microwaves and cordless phones. Thus...standard for SML, then one important consideration would be to ensure that these household products are not available anywhere near or inside the

Effect of mandibular tori on glottic exposure during simulated suspension microlaryngoscopy.

PubMed

Best, Simon R; Kobler, James B; Friedman, Aaron D; Barbu, Anca M; Zeitels, Steven M; Burns, James A

2014-03-01

Mandibular tori have been identified as a contributing factor in difficult exposure during intubation. However, no investigation has measured the effect of mandibular tori on glottic exposure during suspension microlaryngoscopy (SML). The objective of this study was to measure how the size and location of mandibular tori affect glottic exposure during simulated SML at different thyromental distances. Suspension microlaryngoscopy was modeled on an anatomically accurate skull and larynx with thyromental distances between 6 and 12 cm. Mandibular tori were simulated by protruding screws 5 to 15 mm from the lingual aspect of the mandible. The tori were positioned either 15 mm (anterior) or 25 mm (posterior) from the midline of the symphysis. The glottic exposure for the various-size tori in each location was measured by recording the displacement of the glottiscope tip relative to the most anterior exposure achievable without tori. The glottiscope angle relative to the horizontal plane was measured for each condition. Mandibular tori of more than 10 mm had a significant impact on glottic exposure. Displacement of the glottiscope tip ranged from 2 to 9 mm for anteriorly placed tori and from 7 to 29 mm for posteriorly placed tori, with larger tori causing greater displacement. Increasing the thyromental distance increased the posterior glottiscope tip displacement regardless of torus size or location. The glottiscope angle increased with larger tori (12º to 28º), but this angle did not change with increasing thyromental distance. Larger size and more-posterior location of mandibular tori more significantly reduce glottic exposure during SML. The inner table of the mandible is the most relevant anatomic constraint on glottic exposure, which varies with the presence or absence of mandibular tori independent of thyromental distance.

Relation of field-aligned currents measured by AMPERE project to solar wind and substorms

NASA Astrophysics Data System (ADS)

McPherron, R. L.; Anderson, B. J.; Chu, X.

2016-12-01

Magnetic perturbations measured in the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) by the Iridium constellation of spacecraft have been processed to obtain the time history of field-aligned currents (FAC) connecting the magnetosphere to the ionosphere. We find that the strength of these currents is closely related to the strength of the solar wind driver defined as a running average of the previous three hours of the optimum AL (auroral lower) coupling function. The relation is well represented by a saturation model I = A*S*Ss/(S+Ss) with I the current strength in mega Amps, S the driver strength in mV/m, Ss the saturation value of 7.78 mV/m, and A = 2.55 scales the relation to units of current. We also find that in general the upward current on the nightside increases with each substorm expansion onset defined by a combination of the SuperMag SML (SuperMag AL) and midlatitude positive bay (MPB) onset lists. A superposed epoch analysis using 700 onsets in 2010 shows the following: solar wind coupling peaks at expansion onset; dayside outward current starts to increase one hour before onset while nightside outward current starts suddenly at onset; nightside outward current reaches a peak at 28 minutes as do SML and MPB indices; FAC, SML, and MPB respectively take 1, 2, and 3 hours to decay to background. The data indicate that the substorm current wedge is superposed on a pre-existing field-aligned current system and that the location and properties of the current wedge can be studied with the AMPERE data.

U.S. EPA, Pesticide Product Label, , 01/31/1985

EPA Pesticide Factsheets

2011-04-14

... tt o,.v,/I(.t"1I \\.oil '') e.;_.i_ I • .,,:1-, ')1 ,;.t~t(J ~;:".I,_ "';.~h .I~ :"'f' '.I!e- ~~. ? O$~I!!' ;. I:'::' ... Sm,l) I r' iy inc Lt'1 Sf'S H'''(helli «:luv,,1' :!lites Ch ... ...

Dependence of Substorm Evolution on Solar Wind Condition: Simulation Study

NASA Astrophysics Data System (ADS)

Kamiyoshikawa, N.; Ebihara, Y.; Tanaka, T.

2017-12-01

A substorm is one of the remarkable disturbances occurring in the magnetosphere. It is known that the substorm occurs frequently when IMF is southward and solar wind speed is high. However, the physical process to determine substorm scale is not well understood. We reproduced substorms by using global MHD simulation, calculated auroral electrojet (ionospheric Hall current) flowing in the ionosphere to investigate the dependence of substorm evolution on solar wind condition. Solar wind speed of 372.4 km/s and IMF Bz of 5.0 nT were imposed to, obtain the quasi-stationary state of the magnetosphere. Then the solar wind parameters were changed as a step function. For the solar wind speed, we assumed 300 km/s, 500 km/s and 700 km/s. For IMF, we assumed -1.0 nT, -3.0 nT, -5.0 nT, -7.0 nT and -9.0 nT. In total, 15 simulation runs were performed. In order to objectively evaluate the substorm, the onset was identified with the method based on the one proposed by Newell et al. (2011). This method uses the SME index that is an extension of the AE index. In this study, the geomagnetic variation induced by the ionospheric Hall current was obtained every 1 degree from the magnetic latitude 40 degrees to 80 degrees and in every 0.5 hours in the magnetic region direction. The upper and the lower envelopes of the geomagnetic variation are regarded as SMU index and SML index, respectively. The larger the solar wind speed, the larger the southward IMF, the more the onset tends to be faster. This tendency is consistent with the onset occurrence probability indicated by Newell et al. (2016). Moreover, the minimum value of the SML index within 30 minutes from the beginning of the onset tends to decrease with the solar wind speed and the magnitude of the southward IMF. A rapid decrease of the SML index can be explained by a rapid increase in the field-aligned currents flowing in and out of the nightside ionosphere. This means that electromagnetic energies flowing into the ionosphere increase abruptly. To the analogy with electric circuit, dynamo is necessary in the magnetosphere to supply electromagnetic energy to the ionosphere as a load. We will discuss the physical process that may determine the intensity of the electrojet as seen by the SML index in terms of energy flow from the solar wind to the ionosphere and the convection by analyzing the global MHD simulation.

Computational Chemistry Modeling of the Atmospheric Fate of Toxic Industrial Compounds (TICs)

DTIC Science & Technology

2007-06-01

1+G(3df,2p) number of atoms and number of basis functions) of the (LRG) compounds under study precludes the use of coupled 0 Zero Point Energy ( ZPE ...overlap (NDDO) The extrapolated energy = E(QCI) + E(LRG) - Hamiltonian that is reparameterized to accurately E(SML) + ZPE reproduce coupled cluster

Evidence of the Value of the Smoking Media Literacy Framework for Middle School Students

ERIC Educational Resources Information Center

Bier, Melinda C.; Zwarun, Lara; Sherblom, Stephen A.

2016-01-01

Background: Susceptibility to future smoking, positive beliefs about smoking, and perceptions of antismoking norms are all factors that are associated with future smoking. In previous research, smoking media literacy (SML) has been associated with these variables, even when controlling for other known risk factors for smoking. However, these…

Observations of marine decoupled boundary layer during the ICOS campaign at the GAW Mace Head station, Ireland.

NASA Astrophysics Data System (ADS)

Milroy, Conor; Martucci, Giovanni; O'Dowd, Colin

2010-05-01

The planetary boundary layer (PBL) top height detections have been retrieved by two ceilometers (Vaisala CL31 and Jenoptik CHM15K) and a microwave radiometer (RPG-HATPRO) based at the Mace Head Research station, Ireland, from the 8th to the 28th of June 2009 during the ICOS Mace Head campaign. Characteristic of this region, with warm waters, the marine boundary layer is typically 2-layered with a surface mixed layer (SML) and a decoupled residual or convective layer (DRCL), above which is the free troposphere (Kunz et al. 2002). The PBL data have been analyzed using a newly developed Temporal Height-Tracking (THT) algorithm (Martucci et al., 2010) for automatic detection of the independent SML and DRCL tops. Daily and weekly averages of the PBL data have been performed to smooth out the short term variability and assess the dependence of the PBL depth on different air masses advected over the Mace Head station. Moreover, a qualitative comparison between the ceilometer and radiometer PBL top detected values has been done to assess their consistency.

Multilinear stress-strain and failure calibrations for Ti-6Al-4V.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corona, Edmundo

This memo concerns calibration of an elastic-plastic J 2 material model for Ti-6Al-4V (grade 5) alloy based on tensile uniaxial stress-strain data obtained in the laboratory. In addition, tension tests on notched specimens provided data to calibrate two ductile failure models: Johnson-Cook and Wellman's tearing parameter. The tests were conducted by Kim Haulen- beek and Dave Johnson (1528) in the Structural Mechanics Laboratory (SML) during late March and early April, 2017. The SML EWP number was 4162. The stock material was a TIMETALR® 6-4 Titanium billet with 9 in. by 9 in. square section and length of 137 in. Themore » product description indicates that it was a forging delivered in annealed condition (2 hours @ 1300oF, AC at the mill). The tensile mechanical properties reported in the material certi cation are given in Table 1, where σ o represents the 0.2% strain offset yield stress, σ u the ultimate stress, ε f the elongation at failure and R.A. the reduction in area.« less

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys.

PubMed

Futch, J Carrie; Griffin, Dale W; Lipp, Erin K

2010-04-01

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.

Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys

USGS Publications Warehouse

Futch, J. Carrie; Griffin, Dale W.; Lipp, Erin K.

2010-01-01

To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.

Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities.

PubMed

Sauret, Caroline; Tedetti, Marc; Guigue, Catherine; Dumas, Chloé; Lami, Raphaël; Pujo-Pay, Mireille; Conan, Pascal; Goutx, Madeleine; Ghiglione, Jean-François

2016-03-01

We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated. Harbors and wastewater outfalls influenced drastically and in a different way the total and active bacterial community structure, but they only impacted the communities from the nearshore zone (<2 km from the shore). By using direct multivariate statistical analysis, we confirmed the significant effect of PAH concentrations on the spatial and temporal dynamic of total and active communities in this area, but this effect was putted in perspective by the importance of other biogeochemical variables.

Genetic aspect of Alzheimer disease: Results of complex segregation analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadonvick, A.D.; Lee, I.M.L.; Bailey-Wilson, J.E.

1994-09-01

The study was designed to evaluate the possibility that a single major locus will explain the segregation of Alzheimer disease (AD). The data were from the population-based AD Genetic Database and consisted of 402 consecutive, unrelated probands, diagnosed to have either `probable` or `autopsy confirmed` AD and their 2,245 first-degree relatives. In this analysis, a relative was considered affected with AD only when there were sufficient medical/autopsy data to support diagnosis of AD being the most likely cause of the dementia. Transmission probability models allowing for a genotype-dependent and logistically distributed age-of-onset were used. The program REGTL in the S.A.G.E.more » computer program package was used for a complex segregation analysis. The models included correction for single ascertainment. Regressive familial effects were not estimated. The data were analyzed to test for single major locus (SML), random transmission and no transmission (environmental) hypotheses. The results of the complex segregation analysis showed that (1) the SML was the best fit, and (2) the non-genetic models could be rejected.« less

Work-Function and Surface Energy Tunable Cyanoacrylic Acid Small-Molecule Derivative Interlayer on Planar ZnO Nanorods for Improved Organic Photovoltaic Performance.

PubMed

Ambade, Swapnil B; Ambade, Rohan B; Bagde, Sushil S; Lee, Soo-Hyoung

2016-12-28

The issue of work-function and surface energy is fundamental to "decode" the critical inorganic/organic interface in hybrid organic photovoltaics, which influences important photovoltaic events like exciton dissociation, charge transfer, photocurrent (J sc ), open-circuit voltage (V oc ), etc. We demonstrate that by incorporating an interlayer of cyanoacrylic acid small molecular layer (SML) on solution-processed, spin-coated, planar ZnO nanorods (P-ZnO NRs), higher photovoltaic (PV) performances were achieved in both inverted organic photovoltaic (iOPV) and hybrid organic photovoltaic (HOPV) devices, where ZnO acts as an "electron-transporting layer" and as an "electron acceptor", respectively. For the tuned range of surface energy from 52.5 to 33 mN/m, the power conversion efficiency (PCE) in bulk heterojunction (BHJ) iOPVs based on poly(3-hexylthiophene) (P3HT) and phenyl-C 60 -butyric acid methyl ester (PC 60 BM) increases from 3.16% to 3.68%, and that based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl)] (PTB7:Th):[6,6]-phenyl C 71 butyric acid methyl ester (PC 71 BM) photoactive BHJ increases from 6.55% to 8.0%, respectively. The improved PV performance in iOPV devices is majorly attributed to enhanced photocurrents achieved as a result of reduced surface energy and greater electron affinity from the covalent attachment of the strong electron-withdrawing cyano moiety, while that in HOPV devices, where PCE increases from 0.21% to 0.79% for SML-modified devices, is ascribed to a large increase in V oc benefitted due to reduced work function effected from the presence of strong dipole moment in SML that points away from P-ZnO NRs.

Middle Adriatic Study of the Sea Surface Films as a Sink and Source of Trace Organics of Marine Aerosols

NASA Astrophysics Data System (ADS)

Frka Milosavljevic, S.; Cvitešić, A.; Kroflič, A.; Šala, M.; Ciglenečki, I.; Grgic, I.

2016-02-01

Properties, (trans)formation, and removal of organic particles remain the least understood aspects of atmospheric chemistry despite the importance of organic aerosol (OA) for both human health and climate change. Recently, organosulfur compounds (OS) have come into the focus of atmospheric research as significant reservoirs of S in the atmosphere, being potentially important components of gas-to-particle conversion and formation of secondary organic aerosol (SOA) especially in the oceanic region. Moreover, nitroaromatic compounds (NAC), as (methyl)nitrocatehols recently reported as potentially toxic constituents of aerosol water soluble organic matter (WSOM) and significant SOA tracers, have not been studied over marine atmosphere till now. A range of global exchange processes between the sea and the atmosphere is hindered by the sea surface microlayer (SML) generally enriched in surface active organics which form films and serve both as a sink and a source of marine OA. To better understand the role of surfactant films at the air-sea interface in global biogeochemistry as well as the sources and transport pathways of marine OA and to estimate their importance in global climate, it is necessary to study chemical composition and properties of trace organics, OS and NAC, in both the SML and marine aerosols as an integrated whole. We will present the first attempt to study marine aerosol WSOM as well as the SML collected in the Middle Adriatic with a special emphasis on its total S and OS content as well as on specific NAC. For that purpose a novel methodological approach capable of their quantification as well as determination of their surfactant nature is applied by combining liquid chromatography mass spectrometry, ion chromatography, inductively coupled plasma mass spectrometry, and electrochemistry. The obtained data are correlated with those for dissolved and particulate organic carbon, water soluble anions and cations, chlorophyll a, nutrients, and surfactants.

You're the Business--A Custom-Made Business Challenge for Modern Languages Students

ERIC Educational Resources Information Center

Penet, Jean-Christophe

2016-01-01

Modern Languages (ML) students often express concerns about their perceived lack of commercial awareness, worrying that this will put them at a disadvantage, compared with business graduates for instance, when applying for jobs. To try and change this perception, Newcastle University's School of Modern Languages (SML) teamed up with the Careers…

Exploring the Moderating Role of Self-Management of Learning in Mobile English Learning

ERIC Educational Resources Information Center

Huang, Rui-Ting

2014-01-01

Although a considerable number of studies have revealed that self-management of learning (SML) could be closely related to learning achievements, there is still a paucity of research investigating the moderating effect of self-management of learning on mobile learning outcomes. Accordingly, the primary purpose of this study was to explore the…

Energy Monitoring and Control Systems--Performance Verification and Endurance Test Procedures.

DTIC Science & Technology

1982-12-01

EM-; tK2 s) trave h.en loadted in qvstem sit ~rp sm:l , o,1 ti-’.~ -1 rouiitthe factoz’, lest. E.VEF.NT Comnmwid the system to display the status of...contractor correction of all outstanding deficiencies . 163 TEST NO: END-i Page I of 1 OBJECTIVE: To demonstrate EMCS normal mode operation 24 TITLE: Endurance

Effect of Chlorine Substitution on Sulfide Reactivity with OH Radicals

DTIC Science & Technology

2008-09-01

Single point energy: MP2/6-311+G(3df,2p) (LRG) • Zero Point Energy from a vibrational frequency analysis: MP2/6-31++G** ( ZPE ) • Extrapolated energy...E(QCI) + E(LARG) – E(SML) + ZPE • Characterize the TS • Use a three-point fit methodology – fit a harmonic potential to three CCSD single point

Tangeretin sensitizes SGS1-deficient cells by inducing DNA damage.

PubMed

Chong, Shin Yen; Wu, Meng-Ying; Lo, Yi-Chen

2013-07-03

Tangeretin, a polymethoxyflavone found in citrus peel, has been shown to have antiatherogenic, anti-inflammatory, and anticarcinogenic properties. However, the underlying target pathways are not fully characterized. We investigated the tangeretin sensitivity of yeast (Saccharomyces cerevisiae) mutants for DNA damage response or repair pathways. We found that tangeretin treatment significantly reduced (p < 0.05) survival rate, induced preferential G1 phase accumulation, and elevated the DNA double-strand break (DSB) signal γH2A in DNA repair-defective sgs1Δ cells, but had no obvious effects on wild-type cells or mutants of the DNA damage checkpoint (including tel1Δ, sml1Δ mec1Δ, sml1Δ mec1Δ tel1Δ, and rad9Δ mutants). Additionally, microarray data indicated that tangeretin treatment up-regulates genes involved in nutritional processing and down-regulates genes related to RNA processing in sgs1Δ mutants. These results suggest tangeretin may sensitize SGS1-deficient cells by increasing a marker of DNA damage and by inducing G1 arrest and possibly metabolic stress. Thus, tangeretin may be suitable for chemosensitization of cancer cells lacking DSB-repair ability.

Inverse Problems in Geodynamics Using Machine Learning Algorithms

NASA Astrophysics Data System (ADS)

Shahnas, M. H.; Yuen, D. A.; Pysklywec, R. N.

2018-01-01

During the past few decades numerical studies have been widely employed to explore the style of circulation and mixing in the mantle of Earth and other planets. However, in geodynamical studies there are many properties from mineral physics, geochemistry, and petrology in these numerical models. Machine learning, as a computational statistic-related technique and a subfield of artificial intelligence, has rapidly emerged recently in many fields of sciences and engineering. We focus here on the application of supervised machine learning (SML) algorithms in predictions of mantle flow processes. Specifically, we emphasize on estimating mantle properties by employing machine learning techniques in solving an inverse problem. Using snapshots of numerical convection models as training samples, we enable machine learning models to determine the magnitude of the spin transition-induced density anomalies that can cause flow stagnation at midmantle depths. Employing support vector machine algorithms, we show that SML techniques can successfully predict the magnitude of mantle density anomalies and can also be used in characterizing mantle flow patterns. The technique can be extended to more complex geodynamic problems in mantle dynamics by employing deep learning algorithms for putting constraints on properties such as viscosity, elastic parameters, and the nature of thermal and chemical anomalies.

Impact of Wet Deposition of Black Carbon on Particle Dynamics in Surface Waters of Halong Bay, North Vietnam

NASA Astrophysics Data System (ADS)

Mari, X.; Guinot, B. P.; Thuoc, C. V.; Brune, J.; Lefebvre, J. P.; Raimbault, P.; Niggemann, J.; Dittmar, T.

2016-02-01

Black Carbon (BC) is an aerosol emitted during biomass burning and fossil fuel combustion. The atmospheric lifetime of Black Carbon (BC) ranges from a few days in rainy climates up to one month in dry regions, and on a global scale wet deposition of atmospheric BC accounts for about 80% of the BC input to the ocean. The rain-mediated input of BC to the ocean was studied in a coastal site located in a regional hotspot of atmospheric BC concentration, North Vietnam. We monitored changes in atmospheric and marine BC during a 24-h cycle impacted by a short and heavy rainfall event. During the rainfall event, atmospheric BC concentration decreased by a factor of 8 (i.e. from 5230 to 660 µg BC m-3). This cleaning of the air column was immediately followed by a significant increase (by a factor of 2 to 4) of particulate BC (PBC) and POC concentrations in the surface microlayer (SML) and at 1.5 m depth. In the SML, this event was also followed by a significant increase of DOC and dissolved BC (DBC) concentrations. Interestingly, the concentration of DOC decreased by >10% after the rainfall at 1.5 m depth, suggesting an adsorption of DOC onto sinking PBC. Concomitantly with the increase in particulate BC, nutrient concentrations increased by a factor of 2 in the SML, while no change was observed in the underlying water column. After the rainfall, the particle size spectra, measured along the water column with a LISST (Laser In-Situ Scattering and Transmissometry probe), changed in that the concentration of small particles (<5 µm) decreased and the concentration of large particles (>100 µm) increased. This alteration of the particle size spectra was restricted to a thin layer of about 20 cm thickness, probably corresponding to a BC-enriched layer adsorbing DOC and small particles, and stimulating aggregation during sinking from the surface to deeper water layers. The concentrations of POC, DOC, PBC, DBC and nutrients reached pre-rainfall levels 4 hours after the event.

Applications of non-standard maximum likelihood techniques in energy and resource economics

NASA Astrophysics Data System (ADS)

Moeltner, Klaus

Two important types of non-standard maximum likelihood techniques, Simulated Maximum Likelihood (SML) and Pseudo-Maximum Likelihood (PML), have only recently found consideration in the applied economic literature. The objective of this thesis is to demonstrate how these methods can be successfully employed in the analysis of energy and resource models. Chapter I focuses on SML. It constitutes the first application of this technique in the field of energy economics. The framework is as follows: Surveys on the cost of power outages to commercial and industrial customers usually capture multiple observations on the dependent variable for a given firm. The resulting pooled data set is censored and exhibits cross-sectional heterogeneity. We propose a model that addresses these issues by allowing regression coefficients to vary randomly across respondents and by using the Geweke-Hajivassiliou-Keane simulator and Halton sequences to estimate high-order cumulative distribution terms. This adjustment requires the use of SML in the estimation process. Our framework allows for a more comprehensive analysis of outage costs than existing models, which rely on the assumptions of parameter constancy and cross-sectional homogeneity. Our results strongly reject both of these restrictions. The central topic of the second Chapter is the use of PML, a robust estimation technique, in count data analysis of visitor demand for a system of recreation sites. PML has been popular with researchers in this context, since it guards against many types of mis-specification errors. We demonstrate, however, that estimation results will generally be biased even if derived through PML if the recreation model is based on aggregate, or zonal data. To countervail this problem, we propose a zonal model of recreation that captures some of the underlying heterogeneity of individual visitors by incorporating distributional information on per-capita income into the aggregate demand function. This adjustment eliminates the unrealistic constraint of constant income across zonal residents, and thus reduces the risk of aggregation bias in estimated macro-parameters. The corrected aggregate specification reinstates the applicability of PML. It also increases model efficiency, and allows-for the generation of welfare estimates for population subgroups.

Machine Learning and Inverse Problem in Geodynamics

NASA Astrophysics Data System (ADS)

Shahnas, M. H.; Yuen, D. A.; Pysklywec, R.

2017-12-01

During the past few decades numerical modeling and traditional HPC have been widely deployed in many diverse fields for problem solutions. However, in recent years the rapid emergence of machine learning (ML), a subfield of the artificial intelligence (AI), in many fields of sciences, engineering, and finance seems to mark a turning point in the replacement of traditional modeling procedures with artificial intelligence-based techniques. The study of the circulation in the interior of Earth relies on the study of high pressure mineral physics, geochemistry, and petrology where the number of the mantle parameters is large and the thermoelastic parameters are highly pressure- and temperature-dependent. More complexity arises from the fact that many of these parameters that are incorporated in the numerical models as input parameters are not yet well established. In such complex systems the application of machine learning algorithms can play a valuable role. Our focus in this study is the application of supervised machine learning (SML) algorithms in predicting mantle properties with the emphasis on SML techniques in solving the inverse problem. As a sample problem we focus on the spin transition in ferropericlase and perovskite that may cause slab and plume stagnation at mid-mantle depths. The degree of the stagnation depends on the degree of negative density anomaly at the spin transition zone. The training and testing samples for the machine learning models are produced by the numerical convection models with known magnitudes of density anomaly (as the class labels of the samples). The volume fractions of the stagnated slabs and plumes which can be considered as measures for the degree of stagnation are assigned as sample features. The machine learning models can determine the magnitude of the spin transition-induced density anomalies that can cause flow stagnation at mid-mantle depths. Employing support vector machine (SVM) algorithms we show that SML techniques can successfully predict the magnitude of the mantle density anomalies and can also be used in characterizing mantle flow patterns. The technique can be extended to more complex problems in mantle dynamics by employing deep learning algorithms for estimation of mantle properties such as viscosity, elastic parameters, and thermal and chemical anomalies.

Size-resolved characterization of the polysaccharidic and proteinaceous components of sea spray aerosol

NASA Astrophysics Data System (ADS)

Aller, Josephine Y.; Radway, JoAnn C.; Kilthau, Wendy P.; Bothe, Dylan W.; Wilson, Theodore W.; Vaillancourt, Robert D.; Quinn, Patricia K.; Coffman, Derek J.; Murray, Benjamin J.; Knopf, Daniel A.

2017-04-01

Dissolved organic polymers released by phytoplankton and bacteria abiologically self-assemble in surface ocean waters into nano-to micro-sized gels containing polysaccharides, proteins, lipids and other components. These gels concentrate in the sea surface microlayer (SML), where they can potentially contribute to sea spray aerosol (SSA). Sea spray is a major source of atmospheric aerosol mass over much of the earth's surface, and knowledge of its properties (including the amount and nature of the organic content), size distributions and fluxes are fundamental for determining its role in atmospheric chemistry and climate. Using a cascade impactor, we collected size-fractionated aerosol particles from ambient air and from freshly generated Sea Sweep SSA in the western North Atlantic Ocean together with biological and chemical characterization of subsurface and SML waters. Spectrophotometric methods were applied to quantify the polysaccharide-containing transparent exopolymer (TEP) and protein-containing Coomassie stainable material (CSM) in these particles and waters. This study demonstrates that both TEP and CSM in surface ocean waters are aerosolized with sea spray with the greatest total TEP associated with particles <180 nm in diameter and >5 000 nm. The higher concentrations of TEP and CSM in particles >5 000 nm most likely reflects collection of microorganism cells and/or fragments. The greater concentration of CSM in larger size particles may also reflect greater stability of proteinaceous gels compared to polysaccharide-rich gels in surface waters and the SML. Both TEP and CSM were measured in the ambient marine air sample with concentrations of 2.1 ± 0.16 μg xanthan gum equivalents (XG eq.) m-3 and 14 ± 1.0 μg bovine serum albumin equivalents (BSA eq.) m-3. TEP in Sea Sweep SSA averaged 4.7 ± 3.1 μg XG eq. m-3 and CSM 8.6 ± 7.3 μg BSA eq. m-3. This work shows the transport of marine biogenic material across the air-sea interface through primary particle emission and the first demonstration of particle size discriminated TEP and CSM characterization of SSA and ambient aerosol under field conditions.

Pressure as a limit to bloater (Coregonus hoyi) vertical migration

USGS Publications Warehouse

TeWinkel, Leslie M.; Fleischer, Guy W.

1998-01-01

Observations of bloater vertical migration showed a limit to the vertical depth changes that bloater experience. In this paper, we conducted an analysis of maximum differences in pressure encountered by bloater during vertical migration. Throughout the bottom depths studied, bloater experienced maximum reductions in swim bladder volume equal to approximately 50-60% of the volume in midwater. The analysis indicated that the limit in vertical depth change may be related to a maximum level of positive or negative buoyancy for which bloater can compensate using alternative mechanisms such as hydrodynamic lift. Bloater may be limited in the extent of migration by either their depth of neutral buoyancy or the distance above the depth of neutral buoyancy at which they can still maintain their position in the water column. Although a migration limit for the bloater population was evident, individual distances of migration varied at each site. These variations in migration distances may indicate differences in depths of neutral buoyancy within the population. However, in spite of these variations, the strong correlation between shallowest depths of migration and swim bladder volume reduction across depths provides evidence that hydrostatic pressure limits the extent of daily vertical movement in bloater.

Is bilingualism associated with a lower risk of dementia in community-living older adults? Cross-sectional and prospective analyses.

PubMed

Yeung, Caleb M; St John, Philip D; Menec, Verena; Tyas, Suzanne L

2014-01-01

The aim of this study was to determine whether bilingualism is associated with dementia in cross-sectional or prospective analyses of older adults. In 1991, 1616 community-living older adults were assessed and were followed 5 years later. Measures included age, sex, education, subjective memory loss (SML), and the modified Mini-mental State Examination (3MS). Dementia was determined by clinical examination in those who scored below the cut point on the 3MS. Language status was categorized based upon self-report into 3 groups: English as a first language (monolingual English, bilingual English) and English as a Second Language (ESL). The ESL category had lower education, lower 3MS scores, more SML, and were more likely to be diagnosed with cognitive impairment, no dementia at both time 1 and time 2 compared with those speaking English as a first language. There was no association between being bilingual (ESL and bilingual English vs. monolingual) and having dementia at time 1 in bivariate or multivariate analyses. In those who were cognitively intact at time 1, there was no association between being bilingual and having dementia at time 2 in bivariate or multivariate analyses. We did not find any association between speaking >1 language and dementia.

Axial cervical vertebrae-based multivariate regression model for the estimation of skeletal-maturation status.

PubMed

Yang, Y-M; Lee, J; Kim, Y-I; Cho, B-H; Park, S-B

2014-08-01

This study aimed to determine the viability of using axial cervical vertebrae (ACV) as biological indicators of skeletal maturation and to build models that estimate ossification level with improved explanatory power over models based only on chronological age. The study population comprised 74 female and 47 male patients with available hand-wrist radiographs and cone-beam computed tomography images. Generalized Procrustes analysis was used to analyze the shape, size, and form of the ACV regions of interest. The variabilities of these factors were analyzed by principal component analysis. Skeletal maturation was then estimated using a multiple regression model. Separate models were developed for male and female participants. For the female estimation model, the adjusted R(2) explained 84.8% of the variability of the Sempé maturation level (SML), representing a 7.9% increase in SML explanatory power over that using chronological age alone (76.9%). For the male estimation model, the adjusted R(2) was over 90%, representing a 1.7% increase relative to the reference model. The simplest possible ACV morphometric information provided a statistically significant explanation of the portion of skeletal-maturation variability not dependent on chronological age. These results verify that ACV is a strong biological indicator of ossification status. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Determination of Polar Cap Boundary for the Substorm Event of 8 March 2008

NASA Astrophysics Data System (ADS)

Wang, Chi; Wang, Jiangyan; Lopez, Ramon; Li, Hui; Zhang, Jiaojiao; Tang, Binbin

2018-05-01

The polar cap boundary (PCB) is a fundamental indicator of magnetospheric activities especially during a substorm cycle. Taking a period on 8 March 2008 as an example, we investigate the location of PCB and its dynamics during a substorm event. The PCB location is determined from the Piecewise Parabolic Method with a Lagrangian Remap (PPMLR) -Magnetohydrodynamic (MHD) simulation data and Defense Meteorological Satellite Program (DMSP) observations, respectively. Model-observation comparison indicates that the PPMLR-MHD model gives a reliable estimate of PCB location during a complex substorm sequence. We further analyze the evolution of PCB in that period. The polar cap expands under southward interplanetary magnetic field (IMF), since the low-latitude dayside reconnection produces new open magnetic flux. Meanwhile, more solar wind energy enters and stores in the magnetosphere with the decreasing SML (SuperMAG Auroral Lower) index. After the substorm expansion onset, the polar cap contracts for a while due to the explosive increase of nightside reconnection. When the IMF direction turns northward, the polar cap contracts continuously, since the dayside reconnection ceases and no more open magnetic flux are supplied, and the storage energy in the magnetosphere releases with the increasing SML index. The model results are in good accord with the features from observations.

Assessment of NASA GISS CMIP5 ModelE simulated clouds and TOA radiation budgets using satellite observations over the southern mid-latitudes

NASA Astrophysics Data System (ADS)

Stanfield, Ryan Evan

Past, current, and future climates have been simulated by the National Aeronautics and Space Administration (NASA) Goddard Institute for Space Studies (GISS) ModelE Global Circulation Model (GCM) and summarized by the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC, AR4). New simulations from the updated CMIP5 version of the NASA GISS ModelE GCM were recently released to the public community during the summer of 2011 and will be included in the upcoming IPCC AR5 ensemble of simulations. Due to the recent nature of these simulations, they have not yet been extensively validated against observations. To assess the NASA GISS-E2-R GCM, model simulated clouds and cloud properties are compared to observational cloud properties derived from the Clouds and Earth's Radiant Energy System (CERES) project using MODerate Resolution Imaging Spectroradiometer (MODIS) data for the period of March 2000 through December 2005. Over the 6-year period, the global average modeled cloud fractions are within 1% of observations. However, further study however shows large regional biases between the GCM simulations and CERES-MODIS observations. The southern mid-latitudes (SML) were chosen as a focus region due to model errors across multiple GCMs within the recent phase 5 of the Coupled Model Intercomparison Project (CMIP5). Over the SML, the GISS GCM undersimulates total cloud fraction over 20%, but oversimulates total water path by 2 g m-2. Simulated vertical cloud distributions over the SML when compared to both CERES-MODIS and CloudSat/CALIPSO observations show a drastic undersimulation of low level clouds by the GISS GCM, but higher fractions of thicker clouds. To assess the impact of GISS simulated clouds on the TOA radiation budgets, the modeled TOA radiation budgets are compared to CERES EBAF observations. Because modeled low-level cloud fraction is much lower than observed over the SML, modeled reflected shortwave (SW) flux at the TOA is 13 W m -2 lower and outgoing longwave radiation (OLR) is 3 W m-2 higher than observations. Finally, cloud radiative effects (CRE) are calculated and compared with observations to fully assess the impact of clouds on the TOA radiation budgets. The difference in clear-sky reflected SW flux between model and observation is only +4 W m-2 while the SW CRE difference is up to 17 W m-2, indicating that most of the bias in SW CRE results from the all-sky bias between the model and observation. A sizeable negative bias of 10 W m-2 in simulated clear-sky OLR has been found due to a dry bias in calculating observed clear-sky OLR and lack of upper-level water vapor at the 100-mb level in the model. The dry bias impacts CRE LW, with the model undersimulating by 13 W m-2. The CRE NET difference is only 5 W m-2 due to the cancellation of SW and LW CRE biases.

A Kirchhoff Approach to Seismic Modeling and Prestack Depth Migration

DTIC Science & Technology

1993-05-01

continuation of sources and geophones by finite difference (S-G finite - difference migration ), are relatively slow and dip-limited. Compared to S-G... finite - difference migration , the Kirchhoff integral implements prestack migration relatively efficiently and has no dip limitation. Liu .Mlodeling and...for modeling and migration . In this paper, a finite - difference algorithm is used to calculate traveltimes and amplitudes. With the help of

THE INFLUENCE OF HIP STRENGTH ON KNEE KINEMATICS DURING A SINGLE-LEGGED MEDIAL DROP LANDING AMONG COMPETITIVE COLLEGIATE BASKETBALL PLAYERS.

PubMed

Suzuki, Hidetomo; Omori, Go; Uematsu, Daisuke; Nishino, Katsutoshi; Endo, Naoto

2015-10-01

A smaller knee flexion angle and larger knee valgus angle during weight-bearing activities have been identified as risk factors for non-contact anterior cruciate ligament (ACL) injuries. To prevent such injuries, attention has been focused on the role of hip strength in knee motion control. However, gender differences in the relationship between hip strength and knee kinematics during weight-bearing activities in the frontal plane have not been evaluated. The purpose of this study was to determine the influence of hip strength on knee kinematics in both genders during a single-legged landing task in the frontal plane. The hypotheses were that 1) subjects with a greater hip strength would demonstrate larger knee flexion and smaller knee valgus and internal rotation angles and 2) no gender differences would exist during the single-legged landing task. Forty-three Japanese collegiate basketball players (20 males, 23 females) participated in this study. Three-dimensional motion analysis was used to evaluate knee kinematics during a single-legged medial drop landing (SML). A hand-held dynamometer was used to assess hip extensor (HEXT), abductor (HAB), and external rotator (in two positions: seated position [SHER] and prone [PHER]) isometric strength. Spearman rank correlation coefficients (ρ) were determined for correlations between hip strength and knee kinematics at initial contact (IC) and peak (PK) during SML (p < 0.05). Negative correlations were observed between the knee valgus angle at IC and HEXT (ρ = -0.48, p = 0.02), HAB (ρ = -0.46, p = 0.03) and PHER (ρ = -0.44, p = 0.04) strength in females. In addition, a significant positive correlation was observed between the knee flexion angle at PK and HEXT strength (ρ = 0.61, p = 0.004) in males. Significant correlations between hip strength and knee kinematics during SML were observed in both genders. Hip strength may, therefore, play an important role in knee motion control during sports activities, suggesting that increased hip strength may help to prevent non-contact ACL injuries in athletes of both genders. Moreover, gender-specific programs may be needed to control abnormal knee motion, as the influence of hip strength on knee kinematics may differ based on gender. 3.

Tests of Parameterized Langmuir Circulation Mixing in the Oceans Surface Mixed Layer II

DTIC Science & Technology

2017-08-11

inertial oscillations in the ocean are governed by three-dimensional processes that are not accounted for in a one-dimensional simulation , and it was...Unlimited 52 Paul Martin (228) 688-5447 Recent large-eddy simulations (LES) of Langmuir circulation (LC) within the surface mixed layer (SML) of...used in the Navy Coastal Ocean Model (NCOM) and tested for (a) a simple wind-mixing case, (b) simulations of the upper ocean thermal structure at Ocean

The Seismic Design of Waterfront Retaining Structures

DTIC Science & Technology

1992-11-01

h*ho Hf a. Surcharge 81’ ’ S2- I • 040. K A[ Vih . V,., H - H, ) • • - V,,.H,] , b. Effective horizontal earth pressure - B= 0 degrees Figure...distance between the anchor and the sheet pile. Tuo anchored bulkheads were in place in the harbor of San Antnnio, Chile , during the very large earthquake...Engineering, Santiago, Chile . Provost, J. 1981 (Jan). "DYNAFLOW - A Nonlinear Transient Finite Element Analysis Program, Report No. 81-SM-l, Princeton

The microbiome of coral surface mucus has a key role in mediating holobiont health and survival upon disturbance.

PubMed

Glasl, Bettina; Herndl, Gerhard J; Frade, Pedro R

2016-09-01

Microbes are well-recognized members of the coral holobiont. However, little is known about the short-term dynamics of mucus-associated microbial communities under natural conditions and after disturbances, and how these dynamics relate to the host's health. Here we examined the natural variability of prokaryotic communities (based on 16S ribosomal RNA gene amplicon sequencing) associating with the surface mucus layer (SML) of Porites astreoides, a species exhibiting cyclical mucus aging and shedding. Shifts in the prokaryotic community composition during mucus aging led to the prevalence of opportunistic and potentially pathogenic bacteria (Verrucomicrobiaceae and Vibrionaceae) in aged mucus and to a twofold increase in prokaryotic abundance. After the release of aged mucus sheets, the community reverted to its original state, dominated by Endozoicimonaceae and Oxalobacteraceae. Furthermore, we followed the fate of the coral holobiont upon depletion of its natural mucus microbiome through antibiotics treatment. After re-introduction to the reef, healthy-looking microbe-depleted corals started exhibiting clear signs of bleaching and necrosis. Recovery versus mortality of the P. astreoides holobiont was related to the degree of change in abundance distribution of the mucus microbiome. We conclude that the natural prokaryotic community inhabiting the coral SML contributes to coral health and that cyclical mucus shedding has a key role in coral microbiome dynamics.

The microbiome of coral surface mucus has a key role in mediating holobiont health and survival upon disturbance

PubMed Central

Glasl, Bettina; Herndl, Gerhard J; Frade, Pedro R

2016-01-01

Microbes are well-recognized members of the coral holobiont. However, little is known about the short-term dynamics of mucus-associated microbial communities under natural conditions and after disturbances, and how these dynamics relate to the host's health. Here we examined the natural variability of prokaryotic communities (based on 16S ribosomal RNA gene amplicon sequencing) associating with the surface mucus layer (SML) of Porites astreoides, a species exhibiting cyclical mucus aging and shedding. Shifts in the prokaryotic community composition during mucus aging led to the prevalence of opportunistic and potentially pathogenic bacteria (Verrucomicrobiaceae and Vibrionaceae) in aged mucus and to a twofold increase in prokaryotic abundance. After the release of aged mucus sheets, the community reverted to its original state, dominated by Endozoicimonaceae and Oxalobacteraceae. Furthermore, we followed the fate of the coral holobiont upon depletion of its natural mucus microbiome through antibiotics treatment. After re-introduction to the reef, healthy-looking microbe-depleted corals started exhibiting clear signs of bleaching and necrosis. Recovery versus mortality of the P. astreoides holobiont was related to the degree of change in abundance distribution of the mucus microbiome. We conclude that the natural prokaryotic community inhabiting the coral SML contributes to coral health and that cyclical mucus shedding has a key role in coral microbiome dynamics. PMID:26953605

Dual-Tree Complex Wavelet Transform and Image Block Residual-Based Multi-Focus Image Fusion in Visual Sensor Networks

PubMed Central

Yang, Yong; Tong, Song; Huang, Shuying; Lin, Pan

2014-01-01

This paper presents a novel framework for the fusion of multi-focus images explicitly designed for visual sensor network (VSN) environments. Multi-scale based fusion methods can often obtain fused images with good visual effect. However, because of the defects of the fusion rules, it is almost impossible to completely avoid the loss of useful information in the thus obtained fused images. The proposed fusion scheme can be divided into two processes: initial fusion and final fusion. The initial fusion is based on a dual-tree complex wavelet transform (DTCWT). The Sum-Modified-Laplacian (SML)-based visual contrast and SML are employed to fuse the low- and high-frequency coefficients, respectively, and an initial composited image is obtained. In the final fusion process, the image block residuals technique and consistency verification are used to detect the focusing areas and then a decision map is obtained. The map is used to guide how to achieve the final fused image. The performance of the proposed method was extensively tested on a number of multi-focus images, including no-referenced images, referenced images, and images with different noise levels. The experimental results clearly indicate that the proposed method outperformed various state-of-the-art fusion methods, in terms of both subjective and objective evaluations, and is more suitable for VSNs. PMID:25587878

Dual-tree complex wavelet transform and image block residual-based multi-focus image fusion in visual sensor networks.

PubMed

Yang, Yong; Tong, Song; Huang, Shuying; Lin, Pan

2014-11-26

This paper presents a novel framework for the fusion of multi-focus images explicitly designed for visual sensor network (VSN) environments. Multi-scale based fusion methods can often obtain fused images with good visual effect. However, because of the defects of the fusion rules, it is almost impossible to completely avoid the loss of useful information in the thus obtained fused images. The proposed fusion scheme can be divided into two processes: initial fusion and final fusion. The initial fusion is based on a dual-tree complex wavelet transform (DTCWT). The Sum-Modified-Laplacian (SML)-based visual contrast and SML are employed to fuse the low- and high-frequency coefficients, respectively, and an initial composited image is obtained. In the final fusion process, the image block residuals technique and consistency verification are used to detect the focusing areas and then a decision map is obtained. The map is used to guide how to achieve the final fused image. The performance of the proposed method was extensively tested on a number of multi-focus images, including no-referenced images, referenced images, and images with different noise levels. The experimental results clearly indicate that the proposed method outperformed various state-of-the-art fusion methods, in terms of both subjective and objective evaluations, and is more suitable for VSNs.

Compact Video Microscope Imaging System Implemented in Colloid Studies

NASA Technical Reports Server (NTRS)

McDowell, Mark

2002-01-01

Long description Photographs showing fiber-optic light source, microscope and charge-coupled discharge (CCD) camera head connected to camera body, CCD camera body feeding data to image acquisition board in PC, and Cartesian robot controlled via PC board. The Compact Microscope Imaging System (CMIS) is a diagnostic tool with intelligent controls for use in space, industrial, medical, and security applications. CMIS can be used in situ with a minimum amount of user intervention. This system can scan, find areas of interest in, focus on, and acquire images automatically. Many multiple-cell experiments require microscopy for in situ observations; this is feasible only with compact microscope systems. CMIS is a miniature machine vision system that combines intelligent image processing with remote control. The software also has a user-friendly interface, which can be used independently of the hardware for further post-experiment analysis. CMIS has been successfully developed in the SML Laboratory at the NASA Glenn Research Center and adapted for use for colloid studies and is available for telescience experiments. The main innovations this year are an improved interface, optimized algorithms, and the ability to control conventional full-sized microscopes in addition to compact microscopes. The CMIS software-hardware interface is being integrated into our SML Analysis package, which will be a robust general-purpose image-processing package that can handle over 100 space and industrial applications.

Centromere replication timing determines different forms of genomic instability in Saccharomyces cerevisiae checkpoint mutants during replication stress.

PubMed

Feng, Wenyi; Bachant, Jeff; Collingwood, David; Raghuraman, M K; Brewer, Bonita J

2009-12-01

Yeast replication checkpoint mutants lose viability following transient exposure to hydroxyurea, a replication-impeding drug. In an effort to understand the basis for this lethality, we discovered that different events are responsible for inviability in checkpoint-deficient cells harboring mutations in the mec1 and rad53 genes. By monitoring genomewide replication dynamics of cells exposed to hydroxyurea, we show that cells with a checkpoint deficient allele of RAD53, rad53K227A, fail to duplicate centromeres. Following removal of the drug, however, rad53K227A cells recover substantial DNA replication, including replication through centromeres. Despite this recovery, the rad53K227A mutant fails to achieve biorientation of sister centromeres during recovery from hydroxyurea, leading to secondary activation of the spindle assembly checkpoint (SAC), aneuploidy, and lethal chromosome segregation errors. We demonstrate that cell lethality from this segregation defect could be partially remedied by reinforcing bipolar attachment. In contrast, cells with the mec1-1 sml1-1 mutations suffer from severely impaired replication resumption upon removal of hydroxyurea. mec1-1 sml1-1 cells can, however, duplicate at least some of their centromeres and achieve bipolar attachment, leading to abortive segregation and fragmentation of incompletely replicated chromosomes. Our results highlight the importance of replicating yeast centromeres early and reveal different mechanisms of cell death due to differences in replication fork progression.

Multi-stack InAs/InGaAs Sub-monolayer Quantum Dots Infrared Photodetectors

DTIC Science & Technology

2013-01-01

013110 (2013) Demonstration of high performance bias-selectable dual- band short-/mid-wavelength infrared photodetectors based on type-II InAs/ GaSb ...been used for the growth of QD structures . These include the formation of self-assembled QD, for example, Stranski-Krastanov (SK) growth mode,8,9 atomic...confinement in SML-QD and the reduction in the amount of InAs used per layer of QD can help stack more layers in a 3-dimensional QD structure . Several

The influence of plasma flows bringing the magnetotail back to a more symmetric configuration

NASA Astrophysics Data System (ADS)

Reistad, J. P.; Østgaard, N.; Laundal, K.; Tenfjord, P.; Snekvik, K.; Haaland, S.; Milan, S. E.; Ohma, A.; Grocott, A.; Oksavik, K.

2017-12-01

Research from the past decades, most importantly conjugate studies, have shown extensive evidence of the Earth's closed magnetotail being highly displaced from the quiet-day configuration in response to the IMF interacting with the magnetosphere. By displaced we here refer to the mapping of magnetic field-lines from one hemisphere to the other. The large-scale ionospheric convection related to such displaced closed field-lines has also been studied, showing that the footprint in one hemisphere tend to move faster to reduce the displacement, a process we refer to as the restoring of symmetry. Although the appearance and occurrence of the plasma flows related to the restoring of symmetry has been shown to have a strong Interplanetary Magnetic Field (IMF) control, its dynamics and relation to internal magnetospheric processes are unknown. Using multiple years of line-of-sight measurements of the ionospheric plasma convection from the Super Dual Auroral Radar Network binned by IMF, season, and SML index, we have found that the restoring symmetry flows dominate the average convection pattern in the nightside ionosphere during low levels of magnetotail activity, quantified by the SML index. For increasing magnetotail activity, signatures of the restoring symmetry process become less and less pronounced in the global average convection maps. This effect is seen for all clock angles away from IMF By = 0. These results are relevant in order to better understand the dynamic evolution of flux-tubes in the asymmetric magnetosphere.

The Hygroscopicity Parameter of Marine Organics in Sea Spray Aerosols

NASA Astrophysics Data System (ADS)

Boyer, M.; Chang, R. Y. W.

2015-12-01

The effects of aerosols on climate are poorly understood, specifically with respect to their influence on cloud properties. Since oceans cover >70% of Earth's surface, sea spray aerosols (SSA), which act efficiently as cloud condensation nuclei (CCN), may have important implications on Earth's radiation budget. Surface active organic species readily accumulate in the sea surface microlayer (SML), located at the ocean-atmosphere interface, and transfer onto nascent SSA. While it is understood that SSA are commonly enriched with organics, the resulting effect of the organic content on CCN activation remains unresolved. The hygroscopicity parameter, kappa (k), allows for the cloud nucleating properties of individual components to be predicted in particles of mixed composition; however, most studies typically infer k from ambient measurements without assessing the contribution of the individual components to the overall k. In this study, a method for quantifying the cloud nucleating properties of the organic species in surface seawater using k-Kohler theory is proposed. Ambient SML and bulk water samples will be collected and atomized to generate particles such that the overall k can be inferred from CCN measurements. The inorganic and organic components will be quantified, and the organic component will be separated so that the hygroscopicity of only the organic constituents can be determined. By comparing the inferred k values for the samples before and after removal of the inorganic component, the hygroscopicity of the organic constituents alone can be calculated, providing insight on the effect of organic species on CCN activation in SSA.

Reservoir zonation based on statistical analyses: A case study of the Nubian sandstone, Gulf of Suez, Egypt

NASA Astrophysics Data System (ADS)

El Sharawy, Mohamed S.; Gaafar, Gamal R.

2016-12-01

Both reservoir engineers and petrophysicists have been concerned about dividing a reservoir into zones for engineering and petrophysics purposes. Through decades, several techniques and approaches were introduced. Out of them, statistical reservoir zonation, stratigraphic modified Lorenz (SML) plot and the principal component and clustering analyses techniques were chosen to apply on the Nubian sandstone reservoir of Palaeozoic - Lower Cretaceous age, Gulf of Suez, Egypt, by using five adjacent wells. The studied reservoir consists mainly of sandstone with some intercalation of shale layers with varying thickness from one well to another. The permeability ranged from less than 1 md to more than 1000 md. The statistical reservoir zonation technique, depending on core permeability, indicated that the cored interval of the studied reservoir can be divided into two zones. Using reservoir properties such as porosity, bulk density, acoustic impedance and interval transit time indicated also two zones with an obvious variation in separation depth and zones continuity. The stratigraphic modified Lorenz (SML) plot indicated the presence of more than 9 flow units in the cored interval as well as a high degree of microscopic heterogeneity. On the other hand, principal component and cluster analyses, depending on well logging data (gamma ray, sonic, density and neutron), indicated that the whole reservoir can be divided at least into four electrofacies having a noticeable variation in reservoir quality, as correlated with the measured permeability. Furthermore, continuity or discontinuity of the reservoir zones can be determined using this analysis.

The causes of international labor migrations--a demand-determined approach.

PubMed

Straubhaar, T

1986-01-01

The author first studies the reasons why people migrate using a neoclassical approach concerning income differentials. He tests this approach empirically and demonstrates its limits. A demand-determination approach based on human capital theory is then outlined to overcome these limits and to take into account restrictive immigration controls. Migration from Italy, Spain, Greece, Portugal, and Turkey to the European Community destination countries is examined. It is concluded that "the demand for immigrants in the destination country is the decisive condition for the phenomenon of international labor migration, and the supply of migration-willing workers is only a necessary condition." excerpt

Spin-pumping and spin-Hall magnetoresistance (SMR) at transition metal interfaces: case of (Co/Pt) (Conference Presentation)

NASA Astrophysics Data System (ADS)

Jaffres, Henri; George, Jean-Marie; Laczowski, Piotr; Reyren, Nicolas; Vila, Laurent

2016-10-01

Spintronic phenomena are made possible via the diffusion of spin-currents or the generation of spin-accumulation. Spinorbitronics uses the electronic spin-orbit coupling (SOC) and emerges as a new route to create spin-currents in the transverse direction of the charge flow. This is made possible via the intrinsic spin Hall conduction (SHE) of heavy metals or extrinsic spin-Hall effect of metallic alloys. SHE borrows its concept from the anomalous Hall effect (AHE) where the relativistic spin-orbit coupling (SOC) promotes an asymmetric deflection of the spin-current. SHE is now at the base of magnetization commutation and domain wall moving via spin-orbit torque (SOT) and spin-transfer torque operations in the FMR regime. However, the exact anatomy of SOT at spin-orbit active interfaces like Co/Pt is still missing. In the case of Pt, recent studies have put forward the major role played by i) the spin-memory loss (SML) and the electronic transparency at 3d/5d interfaces and ii) the inhomogeneity of the conductivity in the current-in-plane (CIP) geometry to explain the discrepancy in the SHE. Ingredients to consider then are the profiles of both the conductivity and spin-current across the multilayers and spin-transmission. In this talk, we will present robust SMR measurements observed on NiCo/Pt multilayer stacks characterized by a perpendicular magnetic anisotropy (PMA). The SMR occurs for both in-plane magnetization rotation or from nominal out-of-plane to the in-plane direction transverse to the current flow. This clearly departs from standard AMR or pure interfacial anisotropic-AMR symmetries. We analyze in large details our SMR signals for the whole series of samples owing to two main guidelines: i) we consider the exact conductivity profile across the multilayers, in particular near the Co/Pt interface, via the Camley-Barnas approach and ii) we derive the spin current profile generated by SHE along the perpendicular direction responsible for SMR. We consider pure interfacial spin dissipation by SML (decoherence, interfacial enhanced scattering) and give out a general analytical expression for SMR. Our conclusions go towards a robust value of the spin-Hall conductivity and SML like previously published. The CIP spin-Hall angle, of the order of 0.10 is larger than the one found in spin-pumping experiments (CPP geometry) owing to the smaller conductivity at the Co/Pt interface, in agreement with the results of STT-FMR experiments.

Spring migration of waterfowl in the Northern Hemisphere: a management and conservation perspective

USGS Publications Warehouse

Stafford, Joshua D.; Janke, Adam K.; Anteau, Michael J.; Pearse, Aaron T.; Fox, Anthony D.; Elmberg, Johan; Straub, Jacob N.; Eichholz, Michael W.; Arzel, Céline

2014-01-01

Spring migration is a key part of the annual cycle for waterfowl populations in the northern hemisphere, due to its temporal proximity to the breeding season and because resources may be limited at one or more staging sites. Research based on field observations during spring lags behind other periods of the year, despite the potential for fitness consequences through diminished survival or cross-seasonal effects of conditions experienced during migration. Consequently, conservation strategies for waterfowl on spring migration are often only refined versions of practices used during autumn and winter. Here we discuss the current state of knowledge of habitat requirements for waterfowl at their spring migratory sites and the intrinsic and extrinsic factors that lead to variability in those requirements. The provision of plant foods has become the main conservation strategy during spring because of the birds’ energy requirements at this time, not only to fuel migration but to facilitate early clutch formation on arrival at the breeding grounds. Although energy sources are important to migrants, there is little evidence on the extent to which the availability of carbohydrate-based food is limiting for many migratory waterfowl populations.  Such limitation is relatively unlikely among populations that exploit agricultural grain during migration (e.g. arctic-nesting geese), suggesting that conservation strategies for these populations may be misplaced. In general, however, we found few cases in which an ecological understanding of spring-migrating waterfowl was sufficient to indicate true resource limitation during migration, and still fewer cases where conservation efforts ameliorated these limitations. We propose a framework that aims to address knowledge gaps and apply empirical research results to conservation strategies based on documented limitations and associated fitness impacts on migrating waterfowl. Such a strategy would improve allocation of scarce conservation resources during spring migration and greatly improve ecological understanding of migratory waterfowl and their habitats in the northern hemisphere.

Physical limits of cell migration: control by ECM space and nuclear deformation and tuning by proteolysis and traction force.

PubMed

Wolf, Katarina; Te Lindert, Mariska; Krause, Marina; Alexander, Stephanie; Te Riet, Joost; Willis, Amanda L; Hoffman, Robert M; Figdor, Carl G; Weiss, Stephen J; Friedl, Peter

2013-06-24

Cell migration through 3D tissue depends on a physicochemical balance between cell deformability and physical tissue constraints. Migration rates are further governed by the capacity to degrade ECM by proteolytic enzymes, particularly matrix metalloproteinases (MMPs), and integrin- and actomyosin-mediated mechanocoupling. Yet, how these parameters cooperate when space is confined remains unclear. Using MMP-degradable collagen lattices or nondegradable substrates of varying porosity, we quantitatively identify the limits of cell migration by physical arrest. MMP-independent migration declined as linear function of pore size and with deformation of the nucleus, with arrest reached at 10% of the nuclear cross section (tumor cells, 7 µm²; T cells, 4 µm²; neutrophils, 2 µm²). Residual migration under space restriction strongly depended upon MMP-dependent ECM cleavage by enlarging matrix pore diameters, and integrin- and actomyosin-dependent force generation, which jointly propelled the nucleus. The limits of interstitial cell migration thus depend upon scaffold porosity and deformation of the nucleus, with pericellular collagenolysis and mechanocoupling as modulators.

Polyamine-dependent migration of retinal pigment epithelial cells.

PubMed

Johnson, Dianna A; Fields, Carolyn; Fallon, Amy; Fitzgerald, Malinda E C; Viar, Mary Jane; Johnson, Leonard R

2002-04-01

Migration of retinal pigment epithelial (RPE) cells can be triggered by disruption of the RPE monolayer or injury to the neural retina. Migrating cells may re-establish a confluent monolayer, or they may invade the neural retina and disrupt visual function. The purpose of this study was to examine the role of endogenous polyamines in mechanisms of RPE migration. Endogenous polyamine levels were determined in an immortalized RPE cell line, D407, using HPLC. Activities of the two rate-limiting enzymes for polyamine synthesis, ornithine decarboxylase (ODC), and S-adenosylmethionine decarboxylase (SAMdc), were measured by liberation of ((14)CO(2))(.) Migration was assessed in confluent cultures by determining the number of cells migrating into a mechanically denuded area. All measurements were obtained both in control cultures and in cultures treated with synthesis inhibitors that deplete endogenous polyamines. Subcellular localization of endogenous polyamines was determined using a polyamine antibody. The polyamines, spermidine and spermine, as well as their precursor, putrescine, were normal constituents of RPE cells. The two rate-limiting synthetic enzymes were also present, and their activities were stimulated dramatically by addition of serum to the culture medium. Cell migration was similarly stimulated by serum exposure. When endogenous polyamines were depleted, migration was blocked. When polyamines were replenished through uptake, migration was restored. Polyamine immunoreactivity was limited to membrane patches in quiescent cells. In actively migrating and dividing cells, immunoreactivity was enhanced throughout the cytoplasm. Polyamines are essential for RPE migration. Pharmacologic manipulation of the polyamine pathway could provide a therapeutic strategy for regulating anomalous migration.

25MM Plastic Telescoped Cartridge Case Development Program

DTIC Science & Technology

1975-01-01

Mat’ I____ Projectile: 0wq. No. 30033;7,Rev, A, Platic "Band, 3000 Grain. Primer: Type .SmL. , Lot No.,, , Ne. . Flash Tubet.l3TSpe 1ell Project l...8217 _ ’_"__ Projectile: Dwg. No. 300347, Ray. A, Platic Biand, 3000 Graln. Primer: Type P-SIT.ML , Lot No. . No, Flash Tube:c<# 7’Tr-pecla1, Projectile Rot ntlo...Case: N ,o Rev. ___, Mati:.l, ILt Dwg. No,._____ Rev. M Nt l______Projectile: Dwg, No. 300347, ev • A, Platic ’ t -and, 3000 Grain, Primers Type , Lot

[Studies on primary aromatic amines (PAAs) migration from multi-layer plastic food packaging by HPLC method].

PubMed

Cwiek-Ludwicka, Kazimiera; Pawlicka, Marzena; Starski, Andrzej; Półtorak, Hanna; Karłowski, Kazimierz

2011-01-01

The aim of this study was to identify of primary aromatic amines (PAAs) and to determine their migration from plastic food packaging. The magnitude of the migration of these substances from plastic food packaging consists a base for the evaluation of their compliance with the requirements of EU legislation and hazard for human health taking into account their migration into food. The unprinted and printed multi-layer plastic packaging (laminates), domestic and imported, were examined in these studies. PAAs migration tests from the laminates into food simulant (3% acetic acid) was performed according to the appropriate procedures recommended in the EU for testing migration from food contact articles under standard conditions reflecting the real use of laminates (10 days, 40 degrees C) and under ,, worst case scenario" conditions (2 h, 70 degrees C). PAAs present in migration solutions were concentrated on SPE columns and then seven PAAs (aniline, 1,3-phenylenediamine, 2, 6-toluenediamine, 2,4-toluenediamine, 4,4'-oxydianiline, 4,4'-methylenedianiline and 3,3 '-dimethylbenzidyne) were identified and determined by previously validated HPLC-DAD method. Depending on the migration conditions the PAAs content was different. When the "worst case scenario" conditions were applied the migration of 4,4 '-methylenedianiline (4,4 '-MDA) ranged from below detection limit (LOD = 0.51 microg/kg) up to 9.86 microg/kg, and aniline was released in the range from below detection limit (LOD = 0,98 microg/kg) up to 7.04 microg/kg. In two laminate samples of eight examined, the sum of PAAs (aniline and 4,4'-MDA) was 13.32 microg/kg and 14.72 microg/kg showing that the permitted limit (10 microg/kg) was exceeded. In the standard conditions, the migration of aniline and 4,4'-MDA was significantly lower Regarding the carcinogenic potential of PAAs, the laminates causing the amines migration above the permitted limit should not be used as food packaging.

Migration studies of nickel and chromium from ceramic and glass tableware into food simulants.

PubMed

Szynal, Tomasz; Rebeniak, Małgorzata; Mania, Monika

In addition to the release of lead and cadmium from ceramic and glass vessels, (acceptable limits being set by the EU 84/500/EC Directive), other harmful metals can migrate, such as nickel and chromium. Permissible migration limits for these latter metals however have not yet been set in the EU legislation. Both the toxic properties of nickel and chromium and the measures taken by the European Commission Working Group on Food Contact Materials for verifying permissible migration limits for lead, cadmium and other metals from ceramics have acted as drivers for studies on nickel and chromium release from ceramic and glass tableware. To investigate the migration of nickel and chromium into food simulants from ceramic and glassware, available on the Polish market, which are intended for coming into contact with food. Potential consumer exposure can thereby be estimated from the release of these elements into food. Tableware consisted of ceramics and glass vessels generally available on the domestic market, with inner surfaces being mainly coloured and with rim decorations. Migration of nickel and chromium studied from the ceramics was carried out in 4% acetic acid (24 ± 0.5 hrs at 22 ± 2°C), whilst that from glassware in 4% acetic acid (24 ± 0.5 hrs at 22 ± 2°C) and 0.5% citric acid (2 ± 0.1 hrs at 70 ± 2°C). The concentrations of metals which had migrated into the test solutions were measured by using flame atomic absorption spectrometry (FAAS). This analytical procedure had been previously validated by measuring nickel and chromium released into food simulants from ceramic and glass tableware where working ranges, detection limits, quantification limits, repeatability, accuracy, mean recovery and uncertainty were established. Migration of nickel and chromium was measured from 172 ceramic and 52 and glass vessels samples, with all results being below the limits of quantification (LOQ = 0.02 mg/L), excepting one instance where a 0.04 mg/L concentration of nickel was found. The validated methods for measuring chromium achieved the following parameters; 0.02 to 0.80 mg/L operating range, 0.01 mg/L detection limit, 0.02 mg/L limit of quantification, 6% repeatability, 2.8% accuracy, 102% average recovery and 11% uncertainty. For the nickel method the corresponding parameters were 0.02 to 0.80 mg/L work- ing range, 0.02 mg/L limit of quantification, 0.01 mg/L detection limit, 5% repeatability, 6.5% accuracy, 101% average recovery and 12% uncertainty. The tested ceramics and glassware did not pose a threat to human health regarding migration of nickel and chromium, and thus any potential exposure to these metals released from these products into food will be small. However, due to the toxicity of these metals, the migration of nickel and chromium is still required for articles coming into contact with food, which includes metalware. ceramic tableware, ceramics, glassware, food contact articles, nickel, chromium leaching, migration.

Exposure to lead and cadmium released from ceramics and glassware intended to come into contact with food.

PubMed

Rebeniak, Małgorzata; Wojciechowska-Mazurek, Maria; Mania, Monika; Szynal, Tomasz; Strzelecka, Agnieszka; Starska, Krystyna

2014-01-01

The dietary intake of harmful elements, particularly lead and cadmium constitutes a health threat and essential measures should be undertaken to reduce consumer exposure. The latest risk assessments by the European Food Safety Authority (EFSA) and Joint FAO/WHO Expert Committee on Food Additives (JECFA) have indicated that the Provisional Tolerable Weekly Intake (PTWI) for lead and cadmium do not ensure health safety and their review had to be undertaken. Migration from ceramics and glassware intended for food contact is an important source of lead and cadmium intake. To study the release of lead and cadmium from ceramics and glassware (including decorated products) intended for food contact that are available on the Polish market and to assess the resulting health risk to the consumer. Ceramics and glassware (mainly decorated) were sampled from the Polish market during 2010- 2012 throughout the country by staff of the Sanitary-Epidemiological Stations in accordance with monitoring procedures and guidelines designed by the National Institute of Public Health-National Institute of Hygiene. Migration of lead and cadmium was measured by incubating the samples with 4% acetic acid for 24 hours at a temperature of 22±2ºC in the dark. Flame Atomic Absorption Spectrometry (FAAS) was used to measure these elements in food simulant according to a validated and accredited method (PN-EN ISO/IEC 17025). 1273 samples of ceramics and glass wares were analysed in 2010-2012. Lead and cadmium release were usually found to be below analytical detection limits. Permissible migration limits (as prescribed by the legislation) of these metals were rarely exceeded and were reported mainly in articles imported from outside the EU. Two imported and decorated ceramic flat plates released lead at 0.9 and 11.9 mg/dm2 (limit 0.8 mg/dm2) and 5 imported deep plates gave migration values of 4.7 mg/L, 4.9 mg/L, 5.6 mg/L, 6.1 mg/L, 8.6 mg/L (limit 4.0 mg/L). Lead migrations from ceramic ware rims above the 2.0 mg per product limit (as established in Polish Standard PN-B-13210:1997 [16]) were observed in 4 samples, at 2.1, 3.7, 4.2 and 14.4 mg per product, respectively. Migrations of cadmium from the ceramic samples' rims were within permissible limits. Majority of high migration results were obtained for decorated rims of glass vessels for beverages. The highest migration from the rim of an imported glass mug was reported at 163.8 mg/product for lead and at 8.96 mg/product for cadmium. Risk assessment indicated that exposures to lead and cadmium released from ceramic wares based on the migration limits set by the EU legislation lead to human intake close to, or exceeding reference doses. For a 20 kg b.w. child the lead BMDL01 value could thus be exceeded by over 30-fold and the cadmium TWI value 4-fold. Review of EU legislation applicable to lead and cadmium migration limits from ceramics is necessary with an intention to lower such limits. The limits applied to the rims of ceramics and glassware intended for beverages should be included. The release of lead and cadmium at the maximum permissible levels for ceramics may lead to uptakes becoming hazardous to human health. Appropriate measures are thus necessary to reduce sources of exposure. lead, cadmium, ceramic food contact articles, glass food contact articles, lead migration, cadmium migration, lead exposure, cadmium exposure, food contact articles, risk assessment.

Exposure to airborne asbestos in buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, R.J.; Van Orden, D.R.; Corn, M.

The concentration of airborne asbestos in buildings and its implication for the health of building occupants is a major public health issue. A total of 2892 air samples from 315 public, commercial, residential, school, and university buildings has been analyzed by transmission electron microscopy. The buildings that were surveyed were the subject of litigation related to suits alleging the general building occupants were exposed to a potential health hazard as a result of exposure to the presence of asbestos containing materials (ACM). The average concentration of all asbestos structures was 0.02 structures/ml (s/ml) and the average concentration of asbestos greatermore » than or equal to 5 microns long was 0.00013 fibers/ml (f/ml). The concentration of asbestos was higher in schools than in other buildings. In 48% of indoor samples and 75% of outdoor samples, no asbestos fibers were detected. The observed airborne concentration in 74% of the indoor samples and 96% of the outdoor samples is below the Asbestos Hazard Emergency Response Act clearance level of 0.01 s/ml. Finally, using those fibers which could be seen optically, all indoor samples and all outdoor samples are below the Occupational Safety and Health Administration permissible exposure level of 0.1 f/ml for fibers greater than or equal to 5 microns in length. These results provide substantive verification of the findings of the U.S. Environmental Protection Agency public building study which found very low ambient concentrations of asbestos fibers in buildings with ACM, irrespective of the condition of the material in the buildings.« less

What effect do substorms have on the content of the radiation belts?

PubMed Central

Rae, I. J.; Murphy, K. R.; Freeman, M. P.; Huang, C.‐L.; Spence, H. E.; Boyd, A. J.; Coxon, J. C.; Jackman, C. M.; Kalmoni, N. M. E.; Watt, C. E. J.

2016-01-01

Abstract Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV “seed” population into the inner magnetosphere which is subsequently energized through wave‐particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1–3 days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6 days. Increases in radiation belt content show a significant correlation with SML and SYM‐H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels. PMID:27656336

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duffell, Paul C.; MacFadyen, Andrew I.; Farris, Brian D.

Most standard descriptions of Type II migration state that massive, gap-opening planets must migrate at the viscous drift rate. This is based on the idea that the disk is separated into an inner and outer region and gas is considered unable to cross the gap. In fact, gas easily crosses the gap on horseshoe orbits, nullifying this necessary premise which would set the migration rate. In this work, it is demonstrated using highly accurate numerical calculations that the actual migration rate is dependent on disk and planet parameters, and can be significantly larger or smaller than the viscous drift rate. Inmore » the limiting case of a disk much more massive than the secondary, the migration rate saturates to a constant that is sensitive to disk parameters and is not necessarily of the order of the viscous rate. In the opposite limit of a low-mass disk, the migration rate decreases linearly with disk mass. Steady-state solutions in the low disk mass limit show no pile-up outside the secondary's orbit, and no corresponding drainage of the inner disk.« less

Assessing Risk-Based Upper Limits of Melamine Migration from Food Containers.

PubMed

Ling, Min-Pei; Lien, Keng-Wen; Hsieh, Dennis P H

2016-12-01

Melamine contamination of food has become a major food safety issue because of incidents of infant disease caused by exposure to this chemical. This study was aimed at establishing a safety limit in Taiwan for the degree of melamine migration from food containers. Health risk assessment was performed for three exposure groups (preschool children, individuals who dine out, and elderly residents of nursing homes). Selected values of tolerable daily intake (TDI) for melamine were used to calculate the reference migration concentration limit (RMCL) or reference specific migration limit (RSML) for melamine food containers. The only existing values of these limits for international standards today are 1.2 mg/L (0.2 mg/dm 2 ) in China and 30 mg/L (5 mg/dm 2 ) in the European Union. The factors used in the calculations included the specific surface area of food containers, daily food consumption rate, body weight, TDI, and the percentile of the population protected at a given migration concentration limit (MCL). The results indicate that children are indeed at higher risk of melamine exposure at toxic levels than are other groups and that the 95th percentile of MCL (specific surface area = 5) for children aged 1-6 years should be the RMCL (0.07 mg/dm 2 ) for protecting the sensitive and general population. © 2016 Society for Risk Analysis.

Econometric Models of U.S. Navy Career Petty Officer Retention.

DTIC Science & Technology

1981-06-01

PF AD-AL04 076 NAVAL POSTGRADUATE SCHOOL MONTEREY CA F/6 5/9 ECONO ETRIC MODELS OF U.S. NAVY CAREER PETTY OFFICER RETENTION.(Ul JUN 81 J J B PKO...THESIS D . ECONOMETRIC MODELS OF U. S. NAVY CAREER PETTY OFFICER RETENTION SML Vby John Joseph Bepko III June 1981 Thesis Advisor: George W. Thomas...DOCUMENTATION PACE 33703 coTu~rwc oEm 0419PsR 01N1911VT*48~ &GM01 1𔃻. 411CIP1SIMYS CATALOG IulmSIS Econometric Models of U. S. Navy Career Petty 1’ t h s s j

New Approaches to Chemotherapy of Viral Diseases.

DTIC Science & Technology

1978-04-19

interruptions/k minutes ; SM-l2l3 treated : 277 li g ht beam interruptions/k minutes) and thus the drug does not appear to have a depressant effect ...the In teraction of SM-lZi3 with i~~uncmoduIetory stressors; end (b)the effects of 511-1213 on macrophage function . Psychosocial stress Induced by... effects on lumtedlate and delayed type hypersensitivity r.spons.~ to R8C~~~~— DO ,, 1473 £DITIpN 0? I NOV 55 I GIb lETS S/R oioS-oi4-uO i I SECURItY

Validation of the SMOS-MIRAS Soil Moisture Product (SML2UDP) in the Pampean Region of Argentina

NASA Astrophysics Data System (ADS)

Niclòs, Raquel; Rivas, Raúl; Sánchez, Juan Manuel; García-Santos, Vicente; Doña, Carolina; Valor, Enric; Holzman, Mauro; Bayala, Martín Ignacio; Carmona, Facundo; Ocampo, Dora; Soldano, Alvaro; Thibeault, Marc

2014-05-01

A validation campaign was carried out to evaluate the SMOS-MIRAS Soil Moisture (SM) SML2UDP product (v5.51) in the Pampean Region of Argentina on February 2013. The study area was selected because it is a vast area of flatlands containing quite homogeneous rainfed croplands, with prevalence of soybean crops, considered SMOS nominal land uses (i.e., crops with vegetation heights not exceeding 1 to 2 m by opposition to trees). Transects of ground SM measurements were collected by Delta-T ThetaProbe ML2x SM probes within four ISEA-4H9 DGG SMOS nodes. The SM data obtained by each probe transect in each parcel were checked by collecting soil samples in the same parcels at the same time and measuring their masses. The gravimetric method was used to obtain reference values. An uncertainty of ± 0.03 m3m-3 was obtained for the ML2x probes. Additionally, they were calibrated in the laboratory for different SMs by saturating and drying a specific and representative variety of soil samples collected from the experimental parcels (loam, clay loam and silt loam samples). This calibration showed again accurate operations for the ML2x probes, which even attain uncertainties of ±0.01 m3m-3, in agreement with the manufacturer. The comparison of the SM transect data collected during the campaign with the SMOS-MIRAS SML2UDP product values showed a negative bias between concurrent SMOS data and ground SM measurements, which means a slight SMOS-MIRAS underestimation, and a standard deviation of ± 0.06 m3m-3. The validation sites were selected taking as reference the locations of permanent SM stations property of the Argentinean Comisión Nacional de Actividades Espaciales (CONAE, National Commission of Space Activities), Instituto Nacional de Tecnología Agropecuaria (INTA, National Institute of Farming Technology) and Instituto de Hidrología de Llanuras (IHLLA, Plain Hydrology Institute). During the campaign several transects were carried out in the parcels where permanent SM stations were located, mainly in those within one of the nodes (with 5 stations inside). The objective was to evaluate the station SM data reliability at the SMOS spatial resolution with the aim of using station data series as reference for SMOS-MIRAS SM product validations. A linear correlation was obtained between the ground SM values and the SM station data within the node, with a coefficient of determination of 0.98 and a fitting error of ± 0.010 m3m-3. Therefore, the station data adjusted to obtain node representative values are being evaluated as reference data to extend the validation of SMOS-retrieved data beyond the campaign results.

Migration and HIV prevention programmes: linking structural factors, culture, and individual behaviour--an Israeli experience.

PubMed

Soskolne, Varda; Shtarkshall, Ronny A

2002-10-01

Migration is one of the structural factors associated with HIV infections, but the dynamic and complex role of migrant situations as determinants of HIV-related vulnerability is still a major issue for social science research. Moreover, interventions to address the specific structural and contextual factors inherent in this association are limited and many do not take into account the cultural components. This paper presents a multi-level framework for analysis of the links between migration and HIV. It includes the association of migration with structural macro factors-lower socio-economic status and limited power in the new society; intermediate structural factors-limited social capital and bi-directional interaction of cultural norms; and individual-level factors-stressors unique to the migration context, depleted psychosocial resources, loss of cultural beliefs and low use of health services. All these factors affect risky sexual behaviour and transmission of HIV. The paper utilises those elements of the framework that are relevant to the specific needs of immigrant populations from the former Soviet Union and from Ethiopia in Israel. We demonstrate their application to integrated, multi-level HIV prevention interventions and propose several special principles for development of migration-related HIV prevention programmes.

Does Migration Limit the Effect of Health Insurance on Hypertension Management in China?

PubMed

Fang, Hai; Jin, Yinzi; Zhao, Miaomiao; Zhang, Huyang; A Rizzo, John; Zhang, Donglan; Hou, Zhiyuan

2017-10-20

Background: In China, rapid urbanization has caused migration from rural to urban areas, and raised the prevalence of hypertension. However, public health insurance is not portable from one place to another, and migration may limit the effectiveness of this non-portable health insurance on healthcare. Our study aims to investigate whether migration limits the effectiveness of health insurance on hypertension management in China. Methods: Data were obtained from the national baseline survey of the China Health and Retirement Longitudinal Study in 2011, including 4926 hypertensive respondents with public health insurance. Outcome measures included use of primary care, hypertension awareness, medication use, blood pressure monitoring, physician advice, and blood pressure control. Multivariate logistic regressions were estimated to examine whether the effects of rural health insurance on hypertension management differed between those who migrated to urban areas and those who did not migrate and lived in rural areas. Results: Among hypertensive respondents, 60.7% were aware of their hypertensive status. Compared to rural residents, the non-portable feature of rural health insurance significantly reduced rural-to-urban migrants' probabilities of using primary care by 7.8 percentage points, hypertension awareness by 8.8 percentage points, and receiving physician advice by 18.3 percentage points. Conclusions: In China, migration to urban areas limited the effectiveness of rural health insurance on hypertension management due to its non-portable nature. It is critical to improve the portability of rural health insurance, and to extend urban health insurance and primary care coverage to rural-to-urban migrants to achieve better chronic disease management.

Does Migration Limit the Effect of Health Insurance on Hypertension Management in China?

PubMed Central

Fang, Hai; Jin, Yinzi; Zhang, Huyang; A. Rizzo, John; Zhang, Donglan; Hou, Zhiyuan

2017-01-01

Background: In China, rapid urbanization has caused migration from rural to urban areas, and raised the prevalence of hypertension. However, public health insurance is not portable from one place to another, and migration may limit the effectiveness of this non-portable health insurance on healthcare. Our study aims to investigate whether migration limits the effectiveness of health insurance on hypertension management in China. Methods: Data were obtained from the national baseline survey of the China Health and Retirement Longitudinal Study in 2011, including 4926 hypertensive respondents with public health insurance. Outcome measures included use of primary care, hypertension awareness, medication use, blood pressure monitoring, physician advice, and blood pressure control. Multivariate logistic regressions were estimated to examine whether the effects of rural health insurance on hypertension management differed between those who migrated to urban areas and those who did not migrate and lived in rural areas. Results: Among hypertensive respondents, 60.7% were aware of their hypertensive status. Compared to rural residents, the non-portable feature of rural health insurance significantly reduced rural-to-urban migrants’ probabilities of using primary care by 7.8 percentage points, hypertension awareness by 8.8 percentage points, and receiving physician advice by 18.3 percentage points. Conclusions: In China, migration to urban areas limited the effectiveness of rural health insurance on hypertension management due to its non-portable nature. It is critical to improve the portability of rural health insurance, and to extend urban health insurance and primary care coverage to rural-to-urban migrants to achieve better chronic disease management. PMID:29053607

Short-range, overpressure-driven methane migration in coarse-grained gas hydrate reservoirs

DOE PAGES

Nole, Michael; Daigle, Hugh; Cook, Ann E.; ...

2016-08-31

Two methane migration mechanisms have been proposed for coarse-grained gas hydrate reservoirs: short-range diffusive gas migration and long-range advective fluid transport from depth. Herein we demonstrate that short-range fluid flow due to overpressure in marine sediments is a significant additional methane transport mechanism that allows hydrate to precipitate in large quantities in thick, coarse-grained hydrate reservoirs. Two-dimensional simulations demonstrate that this migration mechanism, short-range advective transport, can supply significant amounts of dissolved gas and is unencumbered by limitations of the other two end-member mechanisms. Here, short-range advective migration can increase the amount of methane delivered to sands as compared tomore » the slow process of diffusion, yet it is not necessarily limited by effective porosity reduction as is typical of updip advection from a deep source.« less

Short-range, overpressure-driven methane migration in coarse-grained gas hydrate reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nole, Michael; Daigle, Hugh; Cook, Ann E.

Two methane migration mechanisms have been proposed for coarse-grained gas hydrate reservoirs: short-range diffusive gas migration and long-range advective fluid transport from depth. Herein we demonstrate that short-range fluid flow due to overpressure in marine sediments is a significant additional methane transport mechanism that allows hydrate to precipitate in large quantities in thick, coarse-grained hydrate reservoirs. Two-dimensional simulations demonstrate that this migration mechanism, short-range advective transport, can supply significant amounts of dissolved gas and is unencumbered by limitations of the other two end-member mechanisms. Here, short-range advective migration can increase the amount of methane delivered to sands as compared tomore » the slow process of diffusion, yet it is not necessarily limited by effective porosity reduction as is typical of updip advection from a deep source.« less

Country-Specific Effects of Climate Variability on Human Migration.

PubMed

Gray, Clark; Wise, Erika

2016-04-01

Involuntary human migration is among the social outcomes of greatest concern in the current era of global climate change. Responding to this concern, a growing number of studies have investigated the consequences of short to medium-term climate variability for human migration using demographic and econometric approaches. These studies have provided important insights, but at the same time have been significantly limited by lack of expertise in the use of climate data, access to cross-national data on migration, and attention to model specification. To address these limitations, we link data on internal and international migration over a 6-year period from 9,812 origin households in Kenya, Uganda, Nigeria, Burkina Faso and Senegal to high-resolution gridded climate data from both station and satellite sources. Analyses of these data using several plausible specifications reveal that climate variability has country-specific effects on migration: Migration tends to increase with temperature anomalies in Uganda, tends to decrease with temperature anomalies in Kenya and Burkina Faso, and shows no consistent relationship with temperature in Nigeria and Senegal. Consistent with previous studies, precipitation shows weak and inconsistent relationships with migration across countries. These results challenge generalizing narratives that foresee a consistent migratory response to climate change across the globe.

Secular Resonance Sweeping of the Main Asteroid Belt During Planet Migration

NASA Astrophysics Data System (ADS)

Minton, David A.; Malhotra, Renu

2011-05-01

We calculate the eccentricity excitation of asteroids produced by the sweeping ν6 secular resonance during the epoch of planetesimal-driven giant planet migration in the early history of the solar system. We derive analytical expressions for the magnitude of the eccentricity change and its dependence on the sweep rate and on planetary parameters; the ν6 sweeping leads to either an increase or a decrease of eccentricity depending on an asteroid's initial orbit. Based on the slowest rate of ν6 sweeping that allows a remnant asteroid belt to survive, we derive a lower limit on Saturn's migration speed of ~0.15 AU Myr-1 during the era that the ν6 resonance swept through the inner asteroid belt (semimajor axis range 2.1-2.8 AU). This rate limit is for Saturn's current eccentricity and scales with the square of its eccentricity; the limit on Saturn's migration rate could be lower if its eccentricity were lower during its migration. Applied to an ensemble of fictitious asteroids, our calculations show that a prior single-peaked distribution of asteroid eccentricities would be transformed into a double-peaked distribution due to the sweeping of the ν6 resonance. Examination of the orbital data of main belt asteroids reveals that the proper eccentricities of the known bright (H <= 10.8) asteroids may be consistent with a double-peaked distribution. If so, our theoretical analysis then yields two possible solutions for the migration rate of Saturn and for the dynamical states of the pre-migration asteroid belt: a dynamically cold state (single-peaked eccentricity distribution with mean of ~0.05) linked with Saturn's migration speed ~4 AU Myr-1 or a dynamically hot state (single-peaked eccentricity distribution with mean of ~0.3) linked with Saturn's migration speed ~0.8 AU Myr-1.

Migration of antimony from PET bottles into beverages: determination of the activation energy of diffusion and migration modelling compared with literature data.

PubMed

Welle, F; Franz, R

2011-01-01

Plastics bottles made from polyethylene terephthalate (PET) are increasingly used for soft drinks, mineral water, juices and beer. In this study a literature review is presented concerning antimony levels found both in PET materials as well as in foods and food simulants. On the other hand, 67 PET samples from the European bottle market were investigated for their residual antimony concentrations. A mean value of 224 ± 32 mg kg(-1) was found, the median was 220 mg kg(-1). Diffusion coefficients for antimony in PET bottle materials were experimentally determined at different temperature between 105 and 150°C. From these data, the activation energy of diffusion for antimony species from the PET bottle wall into beverages and food simulants was calculated. The obtained value of 189 kJ mol(-1) was found to be in good agreement with published data on PET microwave trays (184 kJ mol(-1)). Based on these results, the migration of antimony into beverages was predicted by mathematical migration modelling for different surface/volume ratios and antimony bottle wall concentrations. The results were compared with literature data as well as international legal limits and guidelines values for drinking water and the migration limit set from food packaging legislation. It was concluded that antimony levels in beverages due to migration from PET bottles manufactured according to the state of the art can never reach or exceed the European-specific migration limit of 40 microg kg(-1). Maximum migration levels caused by room-temperature storage even after 3 years will never be essentially higher than 2.5 microg kg(-1) and in any case will be below the European limit of 5 microg kg(-1) for drinking water. The results of this study confirm that the exposure of the consumer by antimony migration from PET bottles into beverages and even into edible oils reaches approximately 1% of the current tolerable daily intake (TDI) established by World Health Organisation (WHO). Having substantiated such low antimony levels in PET-bottled beverages, the often addressed question on oestrogenic effects caused by antimony from PET bottles appears to be groundless.

Probabilistic migration modelling focused on functional barrier efficiency and low migration concepts in support of risk assessment.

PubMed

Brandsch, Rainer

2017-10-01

Migration modelling provides reliable migration estimates from food-contact materials (FCM) to food or food simulants based on mass-transfer parameters like diffusion and partition coefficients related to individual materials. In most cases, mass-transfer parameters are not readily available from the literature and for this reason are estimated with a given uncertainty. Historically, uncertainty was accounted for by introducing upper limit concepts first, turning out to be of limited applicability due to highly overestimated migration results. Probabilistic migration modelling gives the possibility to consider uncertainty of the mass-transfer parameters as well as other model inputs. With respect to a functional barrier, the most important parameters among others are the diffusion properties of the functional barrier and its thickness. A software tool that accepts distribution as inputs and is capable of applying Monte Carlo methods, i.e., random sampling from the input distributions of the relevant parameters (i.e., diffusion coefficient and layer thickness), predicts migration results with related uncertainty and confidence intervals. The capabilities of probabilistic migration modelling are presented in the view of three case studies (1) sensitivity analysis, (2) functional barrier efficiency and (3) validation by experimental testing. Based on the predicted migration by probabilistic migration modelling and related exposure estimates, safety evaluation of new materials in the context of existing or new packaging concepts is possible. Identifying associated migration risk and potential safety concerns in the early stage of packaging development is possible. Furthermore, dedicated material selection exhibiting required functional barrier efficiency under application conditions becomes feasible. Validation of the migration risk assessment by probabilistic migration modelling through a minimum of dedicated experimental testing is strongly recommended.

Parental Migration and Children's Outcomes in Romania

ERIC Educational Resources Information Center

Robila, Mihaela

2011-01-01

Although Eastern European migration has increased greatly, the research on its impact on children and families has been limited. In this study I examined the impact of parental economic migration on children psychosocial and academic outcomes in Romania, one of largest Eastern European migrant sending country. Surveys were conducted with 382…

Gap opening by gas accretion and influence on planet populations

NASA Astrophysics Data System (ADS)

Crida, A.; Bitsch, B.; Ndugu, N.; Morbidelli, A.

2017-09-01

Giant planets grow and migrate in protoplanetary disks. Because they accrete gas from their horseshoe region until the latter is depleted, we find that giant planets can open a gap before being lost into their central star by type I migration. A reduced type II migration is then enough and necessary to limit the total amount of migration that a giant planet suffers during its formation.

Country-Specific Effects of Climate Variability on Human Migration

PubMed Central

Gray, Clark; Wise, Erika

2016-01-01

Involuntary human migration is among the social outcomes of greatest concern in the current era of global climate change. Responding to this concern, a growing number of studies have investigated the consequences of short to medium-term climate variability for human migration using demographic and econometric approaches. These studies have provided important insights, but at the same time have been significantly limited by lack of expertise in the use of climate data, access to cross-national data on migration, and attention to model specification. To address these limitations, we link data on internal and international migration over a 6-year period from 9,812 origin households in Kenya, Uganda, Nigeria, Burkina Faso and Senegal to high-resolution gridded climate data from both station and satellite sources. Analyses of these data using several plausible specifications reveal that climate variability has country-specific effects on migration: Migration tends to increase with temperature anomalies in Uganda, tends to decrease with temperature anomalies in Kenya and Burkina Faso, and shows no consistent relationship with temperature in Nigeria and Senegal. Consistent with previous studies, precipitation shows weak and inconsistent relationships with migration across countries. These results challenge generalizing narratives that foresee a consistent migratory response to climate change across the globe. PMID:27092012

Quantitative methods for analysing cumulative effects on fish migration success: a review.

PubMed

Johnson, J E; Patterson, D A; Martins, E G; Cooke, S J; Hinch, S G

2012-07-01

It is often recognized, but seldom addressed, that a quantitative assessment of the cumulative effects, both additive and non-additive, of multiple stressors on fish survival would provide a more realistic representation of the factors that influence fish migration. This review presents a compilation of analytical methods applied to a well-studied fish migration, a more general review of quantitative multivariable methods, and a synthesis on how to apply new analytical techniques in fish migration studies. A compilation of adult migration papers from Fraser River sockeye salmon Oncorhynchus nerka revealed a limited number of multivariable methods being applied and the sub-optimal reliance on univariable methods for multivariable problems. The literature review of fisheries science, general biology and medicine identified a large number of alternative methods for dealing with cumulative effects, with a limited number of techniques being used in fish migration studies. An evaluation of the different methods revealed that certain classes of multivariable analyses will probably prove useful in future assessments of cumulative effects on fish migration. This overview and evaluation of quantitative methods gathered from the disparate fields should serve as a primer for anyone seeking to quantify cumulative effects on fish migration survival. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Climate change-related migration and infectious disease.

PubMed

McMichael, Celia

2015-01-01

Anthropogenic climate change will have significant impacts on both human migration and population health, including infectious disease. It will amplify and alter migration pathways, and will contribute to the changing ecology and transmission dynamics of infectious disease. However there has been limited consideration of the intersections between migration and health in the context of a changing climate. This article argues that climate-change related migration - in conjunction with other drivers of migration - will contribute to changing profiles of infectious disease. It considers infectious disease risks for different climate-related migration pathways, including: forced displacement, slow-onset migration particularly to urban-poor areas, planned resettlement, and labor migration associated with climate change adaptation initiatives. Migration can reduce vulnerability to climate change, but it is critical to better understand and respond to health impacts - including infectious diseases - for migrant populations and host communities.

EphrinB3 restricts endogenous neural stem cell migration after traumatic brain injury.

PubMed

Dixon, Kirsty J; Mier, Jose; Gajavelli, Shyam; Turbic, Alisa; Bullock, Ross; Turnley, Ann M; Liebl, Daniel J

2016-11-01

Traumatic brain injury (TBI) leads to a series of pathological events that can have profound influences on motor, sensory and cognitive functions. Conversely, TBI can also stimulate neural stem/progenitor cell proliferation leading to increased numbers of neuroblasts migrating outside their restrictive neurogenic zone to areas of damage in support of tissue integrity. Unfortunately, the factors that regulate migration are poorly understood. Here, we examine whether ephrinB3 functions to restrict neuroblasts from migrating outside the subventricular zone (SVZ) and rostral migratory stream (RMS). We have previously shown that ephrinB3 is expressed in tissues surrounding these regions, including the overlying corpus callosum (CC), and is reduced after controlled cortical impact (CCI) injury. Our current study takes advantage of ephrinB3 knockout mice to examine the influences of ephrinB3 on neuroblast migration into CC and cortex tissues after CCI injury. Both injury and/or ephrinB3 deficiency led to increased neuroblast numbers and enhanced migration outside the SVZ/RMS zones. Application of soluble ephrinB3-Fc molecules reduced neuroblast migration into the CC after injury and limited neuroblast chain migration in cultured SVZ explants. Our findings suggest that ephrinB3 expression in tissues surrounding neurogenic regions functions to restrict neuroblast migration outside the RMS by limiting chain migration. Copyright © 2016 Michael Boutros, German Cancer Research Center, Heidelberg, Germany. Published by Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smalley, John F.

In this study, we demonstrate how small and rapid temperature perturbations (produced by the indirect laser-induced temperature jump (ILIT) technique) of solid metal electrode|electrolyte solution interfaces may be used to determine the potential of zero (total) charge (E pzc) and its temperature derivativemore » $$\\left(\\frac{dEpzc}{dT}\\right)$$ of Au(111) electrode surfaces modified by alkanethiol self-assembled monolayers in contact with high ionic strength (i.e., 1.0 M) aqueous electrolyte solutions. The E pzc’s measured for two different types of SAMs (made from either HS(CH 2) n-1CH 3 (5 ≤ n ≤ 12, E pzc = -(0.99 ± 0.12) V vs SSCE) or HS(CH 2) nOH (3 ≤ n ≤ 16, E pzc = (0.46 ± 0.22) V vs SSCE)) are considerably different than those measured previously at much lower electrolyte solution ionic strengths. For mixed monolayers made from both HS(CH 2) n-1CH 3 and HS(CH 2) nFc (where Fc refers to ferrocene), the difference in Epzc decreases as a function of the surface concentration of the Fc moiety (i.e., [Fc]), and it completely disappears at a surprisingly small [Fc] (~4.0 × 10 –11 mol cm –2). These observations for the Au(111)|hydrophobic (neat and mixed) SAM|aqueous electrolyte solution interfaces, along with the surface potentials (g Sml(dip)) evaluated for the contacting electrolyte solution surfaces of these interfaces, are consistent with a structure for the water molecule components of these surfaces where there is a net orientation of the dipoles of these molecules. Accordingly, the negative (oxygen) ends of these molecules point toward the SAM surface. The positive values of g Sml(dip) evaluated for hydrophilic SAM (e.g., made from HS(CH 2) nOH)|aqueous electrolyte solution interfaces) also indicate that the structure of these interfaces is similar to that of the hydrophobic interfaces. However, g Sml(dip) decreases with increasing ionic strength for the hydrophilic interfaces, while it increases with increasing ionic strength for the hydrophobic interfaces. The data (and calculations) reported in the present work and other studies of hydrophobic (and hydrophilic)|aqueous solution interfaces are as yet insufficient to support a complete explanation for the effects of ionic strength observed in the present study. Nevertheless, an analysis based upon the value of $$\\left(\\frac{dEpzc}{dT}\\right)$$ (= (0.51 ± 0.12) mV/K, essentially the same for SAMs made from both HS(CH 2) n-1CH 3 and HS(CH 2) nOH), determined in the present study provides a further indication that upon formation of the SAM there is a partial charge transfer of electrons from the relevant gold atoms on the Au(111) surface to the sulfur atoms of the alkanethiols.« less

Challenges in researching migration status, health and health service use: an intersectional analysis of a South London community

PubMed Central

Gazard, Billy; Frissa, Souci; Nellums, Laura; Hotopf, Matthew; Hatch, Stephani L.

2015-01-01

Objectives. This study aimed to investigate the associations between migration status and health-related outcomes and to examine whether and how the effect of migration status changes when it is disaggregated by length of residence, first language, reason for migration and combined with ethnicity. Design. A total of 1698 adults were interviewed from 1076 randomly selected households in two South London boroughs. We described the socio-demographic and socio-economic differences between migrants and non-migrants and compared the prevalence of health-related outcomes by migration status, length of residence, first language, reason for migration and migration status within ethnic groups. Unadjusted models and models adjusted for socio-demographic and socio-economic indicators are presented. Results. Migrants were disadvantaged in terms of socio-economic status but few differences were found between migrant and non-migrants regarding health or health service use indicators; migration status was associated with decreased hazardous alcohol use, functional limitations due to poor mental health and not being registered with a general practitioner. Important differences emerged when migration status was disaggregated by length of residence in the UK, first language, reason for migration and intersected with ethnicity. The association between migration status and functional limitations due to poor mental health was only seen in White migrants, migrants whose first language was not English and migrants who had moved to the UK for work or a better life or for asylum or political reasons. There was no association between migration status and self-rated health overall, but Black African migrants had decreased odds for reporting poor health compared to their non-migrant counterparts [odds ratio = 0.15 (0.05–0.48), p < 0.01]. Conclusions. Disaggregating migration status by length of residence, first language and reason for migration as well as intersecting it with ethnicity leads to better understanding of the effect migration status has on health and health service use. PMID:25271468

Thermal Stress Limit Rafting Migration of Seahorses: Prediction Based on Physiological and Behavioral Responses to Thermal Stress

NASA Astrophysics Data System (ADS)

Qin, G.; Li, C.; Lin, Q.

2017-12-01

Marine fish species escape from harmful environment by migration. Seahorses, with upright posture and low mobility, could migrate from unfavorable environment by rafting with their prehensile tail. The present study was designed to examine the tolerance of lined seahorse Hippocampus erectus to thermal stress and evaluate the effects of temperature on seahorse migration. The results figured that seahorses' tolerance to thermal stress was time dependent. Acute thermal stress (30°C) increased breathing rate and HSP genes expression significantly, but didn't affect seahorse feeding behavior. Chronic thermal treatment lead to persistent high expression of HSP genes, higher breathing rate, and decreasing feeding, and final higher mortality, suggesting that seahorse cannot adapt to thermal stress by acclimation. No significant negative effects were found in seahorse reproduction in response to chronic thermal stress. Given that seahorses make much slower migration by rafting on sea surface compared to other fishes, we suggest that thermal stress might limit seahorse migration range. and the influence might be magnified by global warming in future.

Climate change-related migration and infectious disease

PubMed Central

McMichael, Celia

2015-01-01

Anthropogenic climate change will have significant impacts on both human migration and population health, including infectious disease. It will amplify and alter migration pathways, and will contribute to the changing ecology and transmission dynamics of infectious disease. However there has been limited consideration of the intersections between migration and health in the context of a changing climate. This article argues that climate-change related migration - in conjunction with other drivers of migration – will contribute to changing profiles of infectious disease. It considers infectious disease risks for different climate-related migration pathways, including: forced displacement, slow-onset migration particularly to urban-poor areas, planned resettlement, and labor migration associated with climate change adaptation initiatives. Migration can reduce vulnerability to climate change, but it is critical to better understand and respond to health impacts – including infectious diseases - for migrant populations and host communities. PMID:26151221

46 CFR 148.450 - Cargoes subject to liquefaction.

Code of Federal Regulations, 2011 CFR

2011-10-01

... migration and subsequent liquefaction if shipped with moisture content in excess of the transportable moisture limit. (2) Moisture migration is the movement of moisture by settling and consolidation of a...

Data on the migration of health-care workers: sources, uses, and challenges.

PubMed Central

Diallo, Khassoum

2004-01-01

The migration of health workers within and between countries is a growing concern worldwide because of its impact on health systems in developing and developed countries alike. Policy decisions need to be made at the national, regional and international levels to manage more effectively this phenomenon, but those decisions will be effective and correctly implemented and evaluated only if they are based on adequate statistical data. Most statistics on the migration of health-care workers are neither complete nor fully comparable, and they are often underused, limited (because they often give only a broad description of the phenomena) and not as timely as required. There is also a conflict between the wide range of potential sources of data and the poor statistical evidence on the migration of health personnel. There are two major problems facing researchers who wish to provide evidence on this migration: the problems commonly faced when studying migration in general, such as definitional and comparability problems of "worker migrations" and those related to the specific movements of the health workforce. This paper presents information on the uses of statistics and those who use them, the strengths and limitations of the main data sources, and other challenges that need to be met to obtain good evidence on the migration of health workers. This paper also proposes methods to improve the collection, analysis, sharing, and use of statistics on the migration of health workers. PMID:15375450

Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface.

NASA Astrophysics Data System (ADS)

Tinel, Liselotte; Rossignol, Stéphanie; Ciuraru, Raluca; George, Christian

2015-04-01

Investigating the pathway for the photochemical formation of VOCs in presence of an organic monolayer at the air/water interface. Liselotte Tinel, Stéphanie Rossignol, Raluca Ciuraru and Christian George Université de Lyon, Université Lyon 1, CNRS, UMR5256, IRCELYON, Institut de recherches sur la catalyse et l'environnement de Lyon, Villeurbanne, F-69626, France Recently the surface microlayer (SML) has received growing attention for its role in the deposition and emission of trace gases. This SML is presumably a highly efficient environment for photochemical reactions thanks to its physical and chemical properties, showing enrichment in chromophores [1]. Still, little is known about the possible photochemical processes that could influence the emission and deposition of volatile organic compounds (VOCs) in the SML. A recent study underlines the particularity of the presence of an organic microlayer, showing enhanced formation of peptide bonds at the air-water interface, although this reaction is thermodynamically disfavoured in bulk water [2]. Also, emissions of small gas phase carbonyl compounds formed photochemically by dissolved organic matter have been measured above natural water and glyoxal, for example, measured above the open ocean is thought to be photochemically produced [3, 4]. This study presents the results of a set of laboratory studies set up in order to better understand the role of the SML in the photochemical production of VOCs. Recently, our group has shown the formation of VOCs by light driven reactions in a small quartz reactor (14mL) containing aqueous solutions of humic acids (HA) in the presence of an organic (artificial or natural) microlayer [5]. The main VOCs produced were oxidized species, such as aldehydes, ketones and alcohols, as classically can be expected by the oxidation of the organics present at the interface initiated by triplet excited chromophores present in the HA. But also alkenes, dienes, including isoprene and unsaturated aldehydes were detected and a reaction pathway, initiated by a H-abstraction of the surfactant by the excited HA*, has been proposed. This mechanism infers that the presence of the surface microlayer will enhance protonation and self-reactions, leading to the formation of dimers as suggested in [6]. These products could explain the formation of the unsaturated products observed. To confirm the hypothesis of an initiative step of H-abstraction, the system was simplified using OH radicals, generated by the photolysis of H2O2, in presence of an artificial organic layer of nonanoic acid. The VOCs produced, monitored by PTR/SRI-TOF-MS in NO+ and H3O+ ionization mode, were less abundant compared to the system with HA, but the same classes of products could be observed, including oxidation products such as aldehydes but also unsatured products like dienes. The underlying water was sampled before and after the experiment and analysed by HR-ESI-MS, showing mostly enrichment of oxidative products, such as hydroxy- and keto-acids immediately derived from the photochemical oxidation of the nonanoic acid layer. These products, showing lower volatility and higher polarity, partition preferentially to the bulk water. The results of this simplified system confirm the reaction mechanism proposed and the role an organic layer can play in the photochemical formation of VOCs, which could influence the marine boundary layer chemistry. 1. Peter S. Liss, R.A.D., ed. Sea Surface and Global Change. 1997, Cambridge University Press: Cambridge. 509. 2. Griffith, E.C. and V. Vaida, In situ observation of peptide bond formation at the water-air interface. Proceedings of the National Academy of Sciences, 2012. 109(39): p. 15697-15701. 3. Sinreich, R., et al., Ship-based detection of glyoxal over the remote tropical Pacific Ocean. Atmospheric Chemistry and Physics, 2010. 10(23): p. 11359-11371. 4. Kieber, R.J., X.L. Zhou, and K. Mopper, Formation of carbonyl-compounds from uv-induced photodegradation of humic substances in natural-waters - fate of riverine carbon in the sea. Limnology and Oceanography, 1990. 35(7): p. 1503-1515. 5. R. Ciuraru, L. Fine, M. van Pinxteren, B. D'Anna, H. Herrmann, C. George, Unravelling new processes at interfaces: chemical isoprene production at the sea surface. submitted. 6. Griffith, E.C., et al., Photoinitiated Synthesis of Self-Assembled Vesicles. Journal of the American Chemical Society, 2014. 136(10): p. 3784-3787.

Perinuclear Arp2/3-driven actin polymerization enables nuclear deformation to facilitate cell migration through complex environments

PubMed Central

Thiam, Hawa-Racine; Vargas, Pablo; Carpi, Nicolas; Crespo, Carolina Lage; Raab, Matthew; Terriac, Emmanuel; King, Megan C.; Jacobelli, Jordan; Alberts, Arthur S.; Stradal, Theresia; Lennon-Dumenil, Ana-Maria; Piel, Matthieu

2016-01-01

Cell migration has two opposite faces: although necessary for physiological processes such as immune responses, it can also have detrimental effects by enabling metastatic cells to invade new organs. In vivo, migration occurs in complex environments and often requires a high cellular deformability, a property limited by the cell nucleus. Here we show that dendritic cells, the sentinels of the immune system, possess a mechanism to pass through micrometric constrictions. This mechanism is based on a rapid Arp2/3-dependent actin nucleation around the nucleus that disrupts the nuclear lamina, the main structure limiting nuclear deformability. The cells' requirement for Arp2/3 to pass through constrictions can be relieved when nuclear stiffness is decreased by suppressing lamin A/C expression. We propose a new role for Arp2/3 in three-dimensional cell migration, allowing fast-moving cells such as leukocytes to rapidly and efficiently migrate through narrow gaps, a process probably important for their function. PMID:26975831

Insights into Wilson's Warbler migration from analyses of hydrogen stable-isotope ratios

Treesearch

Jeffrey F. Kelly; Viorel Atudorei; Zachary D. Sharp; Deborah M. Finch

2002-01-01

Our ability to link the breeding locations of individual passerines to migration stopover sites and wintering locations is limited. Stable isotopes of hydrogen contained in bird feathers have recently shown potential in this regard. We measured hydrogen stable-isotope ratios (deltaD) of feathers from breeding, migrating, and wintering Wilson's Warblers. Analyses...

76 FR 13069 - Airworthiness Directives; BAE Systems (Operations) Limited Model ATP Airplanes; BAE Systems...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-10

..., an operator found an aileron trim tab hinge pin that had migrated sufficiently to cause a rubbing.... Recently, during a walk round check, an operator found an aileron trim tab hinge pin that had migrated... walk round check, an operator found an aileron trim tab hinge pin that had migrated sufficiently to...

River morphodynamics from space: the Landsat frontier

NASA Astrophysics Data System (ADS)

Schwenk, Jon; Khandelwal, Ankush; Fratkin, Mulu; Kumar, Vipin; Foufoula-Georgiou, Efi

2017-04-01

NASA's Landsat family of satellites have been observing the entire globe since 1984, providing over 30 years of snapshots with an 18 day frequency and 30 meter resolution. These publicly-available Landsat data are particularly exciting to researchers interested in river morphodynamics, who are often limited to use of historical maps, aerial photography, and field surveys with poor and irregular time resolutions and limited spatial extents. Landsat archives show potential for overcoming these limitations, but techniques and tools for accurately and efficiently mining the vault of scenes must first be developed. In this PICO presentation, we detail the problems we encountered while mapping and quantifying planform dynamics of over 1,300 km of the actively-migrating, meandering Ucayali River in Peru from Landsat imagery. We also present methods to overcome these obstacles and introduce the Matlab-based RivMAP (River Morphodynamics from Analysis of Planforms) toolbox that we developed to extract banklines and centerlines, compute widths, curvatures, and angles, identify cutoffs, and quantify planform changes via centerline migration and erosion/accretion over large spatial domains with high temporal resolution. Measurement uncertainties were estimated by analyzing immobile, abandoned oxbow lakes. Our results identify hotspots of planform changes, and combined with limited precipitation, stage, and topography data, we parse three simultaneous controls on river migration: climate, sediment, and meander cutoff. Overall, this study demonstrates the vast potential locked within Landsat archives to identify multi-scale controls on river migration, observe the co-evolution of width, curvature, discharge, and migration, and discover and develop new geomorphic insights.

Moving Beyond Salmon Bias: Mexican Return Migration and Health Selection

PubMed Central

Diaz, Christina J.; Koning, Stephanie M.; Martinez-Donate, Ana P.

2017-01-01

Despite having lower levels of education and limited access to health care services, Mexican immigrants report better health outcomes than U.S.-born individuals. Research suggests that the Mexican health advantage may be partially attributable to selective return migration among less healthy migrants—often referred to as “salmon bias.” Our study takes advantage of a rare opportunity to observe the health status of Mexican-origin males as they cross the Mexican border. To assess whether unhealthy migrants are disproportionately represented among those who return, we use data from two California-based studies: the California Health Interview Survey; and the Migrante Study, a survey that samples Mexican migrants entering and leaving the United States through Tijuana. We pool these data sources to look for evidence of health-related return migration. Results provide mixed support for salmon bias. Although migrants who report health limitations and frequent stress are more likely to return, we find little evidence that chronic conditions and self-reported health are associated with higher probabilities of return. Results also provide some indication that limited health care access increases the likelihood of return among the least healthy. This study provides new theoretical considerations of return migration and further elucidates the relationship between health and migration decisions. PMID:27848222

Moving Beyond Salmon Bias: Mexican Return Migration and Health Selection.

PubMed

Diaz, Christina J; Koning, Stephanie M; Martinez-Donate, Ana P

2016-12-01

Despite having lower levels of education and limited access to health care services, Mexican immigrants report better health outcomes than U.S.-born individuals. Research suggests that the Mexican health advantage may be partially attributable to selective return migration among less healthy migrants-often referred to as "salmon bias." Our study takes advantage of a rare opportunity to observe the health status of Mexican-origin males as they cross the Mexican border. To assess whether unhealthy migrants are disproportionately represented among those who return, we use data from two California-based studies: the California Health Interview Survey; and the Migrante Study, a survey that samples Mexican migrants entering and leaving the United States through Tijuana. We pool these data sources to look for evidence of health-related return migration. Results provide mixed support for salmon bias. Although migrants who report health limitations and frequent stress are more likely to return, we find little evidence that chronic conditions and self-reported health are associated with higher probabilities of return. Results also provide some indication that limited health care access increases the likelihood of return among the least healthy. This study provides new theoretical considerations of return migration and further elucidates the relationship between health and migration decisions.

Limited-memory BFGS based least-squares pre-stack Kirchhoff depth migration

NASA Astrophysics Data System (ADS)

Wu, Shaojiang; Wang, Yibo; Zheng, Yikang; Chang, Xu

2015-08-01

Least-squares migration (LSM) is a linearized inversion technique for subsurface reflectivity estimation. Compared to conventional migration algorithms, it can improve spatial resolution significantly with a few iterative calculations. There are three key steps in LSM, (1) calculate data residuals between observed data and demigrated data using the inverted reflectivity model; (2) migrate data residuals to form reflectivity gradient and (3) update reflectivity model using optimization methods. In order to obtain an accurate and high-resolution inversion result, the good estimation of inverse Hessian matrix plays a crucial role. However, due to the large size of Hessian matrix, the inverse matrix calculation is always a tough task. The limited-memory BFGS (L-BFGS) method can evaluate the Hessian matrix indirectly using a limited amount of computer memory which only maintains a history of the past m gradients (often m < 10). We combine the L-BFGS method with least-squares pre-stack Kirchhoff depth migration. Then, we validate the introduced approach by the 2-D Marmousi synthetic data set and a 2-D marine data set. The results show that the introduced method can effectively obtain reflectivity model and has a faster convergence rate with two comparison gradient methods. It might be significant for general complex subsurface imaging.

Polydatin induces bone marrow stromal cells migration by activation of ERK1/2.

PubMed

Chen, ZhenQiu; Wei, QiuShi; Hong, GuoJu; Chen, Da; Liang, Jiang; He, Wei; Chen, Mei Hui

2016-08-01

Bone marrow stromal cells (BMSCs) have proven to be useful for the treatment of numerous human diseases. However, the reparative ability of BMSCs is limited by their poor migration. Polydatin, widely used in traditional Chinese remedies, has proven to exert protective effects to BMSCs. However, little is known about its role in BMSCs migration. In this study, we studied the effects of polydatin on rat BMSCs migration using the scratch wound healing and transwell migration assays. Our results showed polydatin could promote BMSCs migration. Further experiments showed activation of ERK 1/2, but not JNK, was required for polydatin-induced BMSCs migration, suggesting that polydatin may promote BMSCs migration via the ERK 1/2 signaling pathways. Taken together, our results indicate that polydatin might be beneficial for stem cell replacement therapy by improving BMSCs migration. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

I was never recruited: challenges in cross-Canada nurse mobility.

PubMed

Hall, Linda McGillis; Peterson, Jessica; Sheri, Sheri; Andrews, Gavin; Lalonde, Michelle; Harris, Alexandra; MacDonald-Rencz, Sandra

2013-01-01

The internal migration of nurses within Canada has had limited study. This paper reports the results of a survey of registered nurses and licensed practical nurses who had migrated between the provinces and territories in Canada. Factors contributing to internal nurse mobility included seeking full-time work, opportunities for career advancement and flexible scheduling options. Few nurses received incentives to move between the provinces/territories to work. A number of challenges with internal migration are identified, including complexities related to licensing and limitations in available job information. Implications for nursing health human resources policy related to nurse retention in Canada are identified and discussed.

The development of European standard (CEN) methods in support of European Directives for plastics materials and articles intended to come into contact with foodstuff.

PubMed

Ashby, R

1994-01-01

CEC Directives have been implemented for plastics materials and articles intended to come into contact with foodstuffs. These introduce limits upon the overall migration from plastics into food and food simulants. In addition, specific migration limits or composition limits for free monomer in the final article, have been set for some monomers. Agreed test methods are required to allow these Directives to be respected. CEN, the European Committee for Standardization, has created a working group to develop suitable test methods. This is 'Working Group 5, Chemical Methods of Test', of CEN Technical Committee TC 194, Utensils in contact with food. This group has drafted a ten part standard for determining overall migration into aqueous and fatty food simulants by total immersion, by standard cell, by standard pouch and by filling. This draft standard has been approved by CEN TC 194 for circulation for public comment as a provisional standard, i.e. as an ENV. Further parts of this standard are in preparation for determining overall migration at high temperatures, etc. Simultaneously, Working Group 5 is cooperating with the BCR (Community Bureau of Reference) to produce reference materials with certified values of overall migration. CEN TC 194 Working Group 5 is also drafting methods for monomers subject to limitation in Directive 90/128/EEC. Good progress is being made on the monomers of highest priority but it is recognized that developing methods for all the monomers subject to limitation would take many years. Therefore, collaboration with the BCR, the Council of Europe and others is taking place to accelerate method development.

WARM JUPITERS NEED CLOSE ''FRIENDS'' FOR HIGH-ECCENTRICITY MIGRATION—A STRINGENT UPPER LIMIT ON THE PERTURBER'S SEPARATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Subo; Katz, Boaz; Socrates, Aristotle

2014-01-20

We propose a stringent observational test on the formation of warm Jupiters (gas-giant planets with 10 days ≲ P ≲ 100 days) by high-eccentricity (high-e) migration mechanisms. Unlike hot Jupiters, the majority of observed warm Jupiters have pericenter distances too large to allow efficient tidal dissipation to induce migration. To access the close pericenter required for migration during a Kozai-Lidov cycle, they must be accompanied by a strong enough perturber to overcome the precession caused by general relativity, placing a strong upper limit on the perturber's separation. For a warm Jupiter at a ∼ 0.2 AU, a Jupiter-mass (solar-mass) perturbermore » is required to be ≲ 3 AU (≲ 30 AU) and can be identified observationally. Among warm Jupiters detected by radial velocities (RVs), ≳ 50% (5 out of 9) with large eccentricities (e ≳ 0.4) have known Jovian companions satisfying this necessary condition for high-e migration. In contrast, ≲ 20% (3 out of 17) of the low-e (e ≲ 0.2) warm Jupiters have detected additional Jovian companions, suggesting that high-e migration with planetary perturbers may not be the dominant formation channel. Complete, long-term RV follow-ups of the warm-Jupiter population will allow a firm upper limit to be put on the fraction of these planets formed by high-e migration. Transiting warm Jupiters showing spin-orbit misalignments will be interesting to apply our test. If the misalignments are solely due to high-e migration as commonly suggested, we expect that the majority of warm Jupiters with low-e (e ≲ 0.2) are not misaligned, in contrast with low-e hot Jupiters.« less

Holocene Migrations of Creosote Bush and Pinyon Pines in the Western United States: Implications for the Next Century.

NASA Astrophysics Data System (ADS)

Cole, K. L.; Arundel, S.; Cannella, J.; Fisher, J.; Spaulding, W. G.

2002-12-01

The biogeographic histories of plant species of the arid western United States are becoming evident as more local paleoecological series are developed and compiled into regional databases. Plant macrofossils from packrat (Neotoma spp.) middens have been especially useful for reconstructing past distributions of arid and semi-arid species such as creosote bush (Larrea tridentata) and one and two-needle pinyon pines (Pinus monophylla, P. edulis). These records document the late Wisconsinan ranges of these species and their subsequent Holocene migrations into their current ranges. Creosote bush grew in the lower Colorado River Valley during the late Wisconsinan (Isotope Stage 2). Starting around 11,000 yr B.P., it migrated northward into its present range. By 6000 yr B.P. it grew at higher elevations than at present in the central Mojave Desert, but did not reach its extreme northern limits until around 4000 yr B.P. Other populations, such as near the shrubs upstream limit along the Colorado River, were not established until the last 2500 years. Its arrival at its most northerly sites lagged well behind other desert thermophiles. Single-needle pinyon (Pinus monophylla) migrated northward from the Mojave Desert into the Great Basin arriving near its current northeastern limit in the eastern Great Basin as early as 7000 yr B.P. It migrated more slowly in the western Great Basin possibly not reaching its northwestern limit until the last 2000 years. Colorado pinyon (Pinus edulis) migrated from near its current southern boundary northward reaching the eastern Grand Canyon as early as 10,600 yr B.P. It is not recorded from central Utah until after 7000 yr B.P. It evidently moved northward slowly, arriving at some northerly and easterly stands only within the last 1000 years. These migrational histories reflect a combination of dispersal limitations and gradual climatic changes. But the long migration times required, coupled with their expansion above their modern elevational limits during the middle Holocene, suggest that the primary factor slowing their response was migrational distance rather than a monotonic trend of warming climates through the Holocene. These results have implications for vegetational effects of the expected climate shifts of the next 100 years. Although this change may be as little as a third as the 6oC warming that occurred near the beginning of the Holocene, the past rates of migration suggest that little equilibration with the new climate can be expected in time spans under 1000 years. Also, mapping of 20 climate variables describing the modern climatic tolerances of these species suggests that they already have significant available potential range, mostly to the north of their current ranges, that should now be suitable for their expansion. These results suggest that either the late Holocene populations had not yet equilibrated with the Pleistocene to Holocene change in climate, or that climate has already warmed so much since the Little Ice Age that many species are no longer in equilibrium with late Twentieth Century climate.

Beyond Education and Employment: Exploring Youth Experiences of Their Communities, Place Attachment and Reasons for Migration

ERIC Educational Resources Information Center

Eacott, Chelsea; Sonn, Christopher C.

2006-01-01

The population in rural areas of Australia has been declining for many decades and it has become common practice to blame this decline on the migration of young people due to structural limitations (e.g. education and employment). This study explores factors associated with migration of youth from rural Victoria looking at their experience of…

Novel device (AirWave) to assess endotracheal tube migration: a pilot study.

PubMed

Nacheli, Gustavo Cumbo; Sharma, Manish; Wang, Xiaofeng; Gupta, Amit; Guzman, Jorge A; Tonelli, Adriano R

2013-08-01

Little is known about endotracheal tube (ETT) migration during routine care among critically ill patients. AirWave is a novel device that uses sonar waves to measure ETT migration and obstructions in real time. The aim of the present study is to assess the accuracy of the AirWave to evaluate ETT migration. In addition, we determined the degree of variation in ETT position and tested whether more pronounced migration occurs in specific clinical scenarios. After institutional review board approval, we included mechanically ventilated patients from February 2012 to May 2012. A chest radiography (CXR) was obtained at baseline and 24 hours when clinically indicated. The ETT distance at the lips was recorded at baseline and every 4 hours. The AirWave system continuously recorded ETT position changes from baseline, and luminal obstructions. A total of 42 patients (age: 61 [SD ±13] years, men: 52%) were recruited. A total of 19 patients had measurements of ETT migration at 24 hours by the 3 methodologies used in this study. The mean (SD) of the ETT migration at 24 hours was +0.04 (1.2), -0.42 (0.7) and +0.34 (1.81) cm when measured by portable CXR, ETT distance at the teeth and AirWave device, respectively. Bland-Altman analysis of tube migration at 24 hours comparing the AirWave with CXR readings showed a bias of 0.1 cm with 95% limit of agreement of -3.8 and +4.3 cm. Comparison of tube migration at 24 hours determined by AirWave with ETT distance at the lips revealed a bias of -0.4 with 95% limit of agreement -3.7 to +3 cm, similar to the values observed between CXR and ETT distance at the lips (bias of -0.3 cm, 95% limit of agreement of -3.4 to +2.8 cm). Factors associated with ETT migration at 24 hours were ETT size and initial measurement from ETT tip to carina by portable CXR. AirWave detected in eight patients some degree of ETT obstruction (30% ± 9.6%) that resolved with prompt ETT catheter suction. The AirWave may provide useful information regarding ETT migration and obstruction in real time. Copyright © 2013 Elsevier Inc. All rights reserved.

Appraisal of rural-urban migration determinants: a case study of Constantine, Algeria.

PubMed

Boukhemis, K; Zeghiche, A

1988-02-01

Despite some impressive achievements, Algerian planning strategy has neglected the spatial aspect of development, which has accelerated interregional migration and consequently has reinforced existing urban problems: 1) overcrowding, 2) the housing crisis, 3) unemployment, and 4) inadequate infrastructure services. It has become obvious that policy makers must take into account the major role of migration in balanced economic growth, and yet knowledge of migration patterns and processes is very limited in Algeria. Constantine's geographic location and role as a regional metropolis played an essential part in shaping migration flows. Up to 1966, Constantine's disproportionate growth was largely the result of massive migration. Since then, there has been a noticeable slowdown in migration, and natural increase has become the largest component of urban growth. This change reflects the government's development policies. Migration flows to Constantine have been deflected to the new industrial poles, which offer greater employment opportunities. More knowledge of migration is essential for an understanding of the factors that determine the rate and direction of migration flows.

Migrations and swimming capabilities of endangered pallid sturgeon (Scaphirhynchus albus) to guide passage designs in the fragmented Yellowstone River

USGS Publications Warehouse

Braaten, P. J.; Elliott, Caroline M.; Rhoten, Jason C.; Fuller, D. B.; McElroy, Brandon J.

2015-01-01

Fragmentation of the Yellowstone River is hypothesized to preclude recruitment of endangered Scaphirhynchus albus (pallid sturgeon) by impeding upstream spawning migrations and access to upstream spawning areas, thereby limiting the length of free-flowing river required for survival of early life stages. Building on this hypothesis, the reach of the Yellowstone River affected by Intake Diversion Dam (IDD) is targeted for modification. Structures including a rock ramp and by-pass channel have been proposed as restoration alternatives to facilitate passage. Limited information on migrations and swimming capabilities of pallid sturgeon is available to guide engineering design specifications for the proposed structures. Migration behavior, pathways (channel routes used during migrations), and swimming capabilities of free-ranging wild adult pallid sturgeon were examined using radiotelemetry, and complemented with hydraulic data obtained along the migration pathways. Migrations of 12–26% of the telemetered pallid sturgeon population persisted to IDD, but upstream passage over the dam was not detected. Observed migration pathways occurred primarily through main channel habitats; however, migrations through side channels up to 3.9 km in length were documented. The majority of pallid sturgeon used depths of 2.2–3.4 m and mean water velocities of 0.89–1.83 m/s while migrating. Results provide inferences on depths, velocities, and habitat heterogeneity of reaches successfully negotiated by pallid sturgeon that may be used to guide designs for structures facilitating passage at IDD. Passage will provide connectivity to potential upstream spawning areas on the Yellowstone River, thereby increasing the likelihood of recruitment for this endangered species.

Design of a high-throughput human neural crest cell migration assay to indicate potential developmental toxicants.

PubMed

Nyffeler, Johanna; Karreman, Christiaan; Leisner, Heidrun; Kim, Yong Jun; Lee, Gabsang; Waldmann, Tanja; Leist, Marcel

2017-01-01

Migration of neural crest cells (NCCs) is one of the pivotal processes of human fetal development. Malformations arise if NCC migration and differentiation are impaired genetically or by toxicants. In the currently available test systems for migration inhibition of NCC (MINC), the manual generation of a cell-free space results in extreme operator dependencies, and limits throughput. Here a new test format was established. The assay avoids scratching by plating cells around a commercially available circular stopper. Removal of the stopper barrier after cell attachment initiates migration. This microwell-based circular migration zone NCC function assay (cMINC) was further optimized for toxicological testing of human pluripotent stem cell (hPSC)-derived NCCs. The challenge of obtaining data on viability and migration by automated image processing was addressed by developing a freeware. Data on cell proliferation were obtained by labelling replicating cells, and by careful assessment of cell viability for each experimental sample. The role of cell proliferation as an experimental confounder was tested experimentally by performing the cMINC in the presence of the proliferation-inhibiting drug cytosine arabinoside (AraC), and by a careful evaluation of mitotic events over time. Data from these studies led to an adaptation of the test protocol, so that toxicant exposure was limited to 24 h. Under these conditions, a prediction model was developed that allows classification of toxicants as either inactive, leading to unspecific cytotoxicity, or specifically inhibiting NC migration at non-cytotoxic concentrations.

The Potential and Limitations of Cross-Context Comparative Research on Migration

PubMed Central

Riosmena, Fernando

2017-01-01

This article is an overview of household survey approaches for the comparative study of international migration dynamics. Focusing on differences in the drivers of international mobility at different times and places, I highlight the problems of obtaining data with adequate representation across time periods and geographies, and discuss a broad constellation of prospective and retrospective approaches, paying particular attention to the migration ethnosurvey. I place this methodology within a broader constellation of prospective and retrospective data collection techniques, briefly describing the advantages and disadvantages of each and summarizing the commonalities and differences of ethnosurvey approaches adopted around the world. In particular, I discuss the potential and limitations of cross-context research and suggest post hoc case selection and other adjustments to ameliorate problems. I conclude with ideas about how case and sample selection can help to bolster migration studies in the future. PMID:29093598

Resolving ultrafast exciton migration in organic solids at the nanoscale

NASA Astrophysics Data System (ADS)

Penwell, Samuel B.; Ginsberg, Lucas D. S.; Noriega, Rodrigo; Ginsberg, Naomi S.

2017-11-01

Effectiveness of molecular-based light harvesting relies on transport of excitons to charge-transfer sites. Measuring exciton migration, however, has been challenging because of the mismatch between nanoscale migration lengths and the diffraction limit. Instead of using bulk substrate quenching methods, here we define quenching boundaries all-optically with sub-diffraction resolution, thus characterizing spatiotemporal exciton migration on its native nanometre and picosecond scales. By transforming stimulated emission depletion microscopy into a time-resolved ultrafast approach, we measure a 16-nm migration length in poly(2,5-di(hexyloxy)cyanoterephthalylidene) conjugated polymer films. Combined with Monte Carlo exciton hopping simulations, we show that migration in these films is essentially diffusive because intrinsic chromophore energetic disorder is comparable to chromophore inhomogeneous broadening. Our approach will enable previously unattainable correlation of local material structure to exciton migration character, applicable not only to photovoltaic or display-destined organic semiconductors but also to explaining the quintessential exciton migration exhibited in photosynthesis.

Seasonal Variations of Atmospheric Black Carbon Concentrations and Implications for Nutrient Inputs and Organic Carbon Partitioning in the Marine Coastal Ecosystem of Halong Bay, North Vietnam

NASA Astrophysics Data System (ADS)

Mari, X.; Thuoc, C. V.; Guinot, B. P.; Brune, J.; Lefebvre, J. P.; Raimbault, P.; Niggemann, J.; Dittmar, T.

2016-02-01

Black Carbon (BC) is an aerosol emitted during biomass burning and fossil fuel combustion. On a global scale, BC deposits on the ocean at a rate of 12-45 Tg per year, with higher fluxes in the northern hemisphere and in inter-tropical regions, following the occurrence of hotspots of atmospheric BC concentration. In the present study conducted in a coastal site located in a regional hotspot of atmospheric BC concentration, North Vietnam, we monitored the seasonal variations of atmospheric and marine BC during an annual cycle. Atmospheric BC followed a seasonal pattern characterized by high concentrations during the dry season, i.e. from October to April, and low concentrations during the wet season, i.e. from May to September. This trend is linked to a change in wind regime, with air masses originating from the North during the dry season and from the South during the wet season. On average, the contribution of BC to the particulate and the dissolved organic carbon pools was 43% and 3%, respectively. The concentration of particulate BC (PBC) was on average 50 times higher in the surface microlayer (SML) than in the water column. In the water column, the concentration of PBC was higher during the dry season than the wet season, which is consistent with variations of atmospheric BC concentrations. On the contrary, the concentration of dissolved BC (DBC) was lower during the dry season than the wet season. This seasonal pattern suggests that PBC concentration in coastal marine systems depends upon atmospheric BC concentration, while increased DBC concentration is linked to rainy conditions. The deposition of BC during the dry season was concomitant with a strong enrichment of organic phosphorus in the SML. During the annual cycle, the POC:DOC ratio was positively correlated with the concentration of PBC, suggesting adsorption of DOC onto BC particles and formation of POC via stimulation of aggregation processes.

Does video-assisted mediastinoscopy offer lower false-negative rates for subcarinal lymph nodes compared with standard cervical mediastinoscopy?

PubMed

Citak, Necati; Buyukkale, Songul; Kok, Abdulaziz; Celikten, Alper; Metin, Muzaffer; Sayar, Adnan; Gurses, Atilla

2014-10-01

Theoretically, video-assisted mediastinoscopy (VAM) offers improved staging of subcarinal lymph nodes (LNs) compared with standard cervical mediastinoscopy (SCM). Materials and Between 2006 and 2011, 553 patients (SCM, n = 293; VAM, n = 260) with non-small cell lung carcinoma who underwent mediastinoscopy were investigated. Mediastinoscopy was performed only in select patients based on computed tomography (CT) or positron emission tomography CT scans in our center. The mean number of LNs and stations sampled per case was significantly higher with VAM (n = 7.65 ± 1.68 and n = 4.22 ± 0.83) than with SCM (n = 6.91 ± 1.65 and 3.92 ± 86.4; p < 0.001). The percentage of patients sampled in station 7 was significantly higher with VAM (98.8%) than with SCM (93.8%; p = 0.002). Mediastinal LN metastasis was observed in 114 patients by mediastinoscopy. The remaining 439 patients (203 patients in VAM and 236 in SCM) underwent thoracotomy and systematic mediastinal lymphadenectomy (SML). SML showed mediastinal nodal disease in 23 patients (false-negative [FN] rate, 5.2%). The FN rate was higher with SCM (n = 14, 5.9%) than with VAM (n = 9, 4.4%), although this difference was not statistically significant (p = 0.490). Station 7 was the most predominant station for FN results (n = 15). The FN rate of station 7 was found to be higher with SCM (n = 9, 3.8%) than with the VAM group (n = 6, 2.9%; p = 0.623). FN were more common in mediastinoscopy of subcarinal LNs. VAM allows higher rates of sampling of mediastinal LN stations and station 7, although it did not improve staging of subcarinal LNs. Georg Thieme Verlag KG Stuttgart · New York.

Determination of the overall migration from silicone baking moulds into simulants and food using 1H-NMR techniques.

PubMed

Helling, Ruediger; Mieth, Anja; Altmann, Stefan; Simat, Thomas Joachim

2009-03-01

Different silicone baking moulds (37 samples) were characterized with respect to potential migrating substances using 1H-NMR, RP-HPLC-UV/ELSD and GC techniques. In all cases cyclic organosiloxane oligomers with the formula [Si(CH3)2-O]n were identified (n = 6 ... 50). Additionally, linear, partly hydroxyl-terminated organosiloxanes HO-[Si(CH3)2-O]n-H (n = 7 ... 20) were found in 13 samples. No substances other than siloxanes could be detected, meaning the migrants mainly consist of organopolysiloxanes. Based on this knowledge, a 1H-NMR quantification method for siloxanes was established for the analysis of both simulants and foodstuffs. Validation of the 1H-NMR method gave suitable performance characteristics: limit of detection 8.7 mg kg(-1) oil, coefficient of variation 7.8% (at a level of 1.0 mg kg(-1) food). Migration studies were carried out with simulants (olive oil, isooctane, ethanol (95%), Tenax) as well as preparation of different cakes. From the 1st to 10th experiment, siloxane migration into cakes only slightly decreased, with a significant dependence on fat content. Migration never exceeded a level of 21 mg kg(-1) (3 mg dm(-2)) and was, therefore, well below the overall migration limit of 60 mg kg(-1) (10 mg dm(-2)). However, migration behaviour into simulants differed completely from these results.

Factors influencing the migration of West African health professionals

PubMed Central

Lowe, Mat; Chen, Duan-Rung

2016-01-01

Introduction The West African health sector is characterized by a human resource base lacking in numbers and specialized skills. Among the contributory factors to this lack of human resource for health workforce include but not limited to the migration of health professionals. Methods This cross-sectional survey targeted 118 young professionals who have participated in the Young Professional Internship Program (YPIP) of the West African Health Organization (WAHO), from (2005-2013). It inquired about their socio-demographic characteristics associated with migration and reasons for going to their preferred or most likely destinations through online survey. Results Of the 118 young professionals, 100 responded to the online survey, of which (28%) have migrated and (72%) did not migrate. Migration was more common among males and those (age≤31 years old), single with high dependency level and no previous work experience. Having a medical profession and being posted to urban or semi-urban area was also associated with their emigration. Their most important reasons for going to preferred or most likely destinations were to have fair level of workload, job promotion and limited occupational risks. Conclusion This finding suggests that the migration of health professionals is situation dependent, mediated by basic socio-demographic variables and work related conditions. These issues have implications for curbing the brain drain potential of health professionals in the West African health sector. PMID:27800092

Migration of bisphenol A into canned tomatoes produced in Italy: dependence on temperature and storage conditions.

PubMed

Errico, Sonia; Bianco, Mariangela; Mita, Luigi; Migliaccio, Marina; Rossi, Sergio; Nicolucci, Carla; Menale, Ciro; Portaccio, Marianna; Gallo, Pasquale; Mita, Damiano G; Diano, Nadia

2014-10-01

A method based on solid-phase extraction followed by liquid chromatography, coupled to UV-visible and fluorescence spectrophotometry, has been developed for determination of bisphenol A (BPA) in canned tomatoes. The limit of quantification (LOQ) of the procedure used is 0.03 μM (0.26 μg BPA/kg tomato). For each of three different tomato based products (peeled, cherry and concentrated paste), 16 samples belonging to six commercial brands, retailed in Italian markets, were tested for migration of BPA epoxy-coating cans. All the tomato samples exhibited migration levels below 0.4 μg/kg, while samples subjected to heating process and/or can's damage by denting, exhibited a significant increase in the migration levels. In any case, no sample contained BPA exceeding the European Union limit for migration, set at 600 μg/kg of food. By comparing the results for each brand, no relevant difference in BPA concentration was found depending on the kind of tomato products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Derivation of safe health-based exposure limits for potential consumer exposure to styrene migrating into food from food containers.

PubMed

Gelbke, Heinz-Peter; Banton, Marcy; Faes, Eric; Leibold, Edgar; Pemberton, Mark; Duhayon, Sophie

2014-02-01

Residual styrene present in polystyrene food packaging may migrate into food at low levels. To assure safe use, safe exposure levels are derived for consumers potentially exposed via food using No/Low Adverse Effect Levels from animal and human studies and assessment factors proposed by European organisations (EFSA, ECHA, ECETOC). Ototoxicity and developmental toxicity in rats and human ototoxicity and effects on colour discrimination have been identified as the most relevant toxicological properties for styrene health assessments. Safe exposure levels derived from animal studies with assessment factors of EFSA and ECHA were expectedly much lower than those using the ECETOC approach. Comparable safe exposure levels were obtained from human data with all sets of assessment factors while ototoxicity in rats led to major differences. The safe exposure levels finally selected based on criteria of science and health protection converged to the range of 90-120 mg/person/d. Assuming a consumption of 1 kg food/d for an adult, this translates to 90 mg styrene migration into 1 kg food as safe for consumers. This assessment supports a health based Specific Migration Limit of 90 ppm, a value somewhat higher than the current overall migration limit of 60 ppm in the European Union. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Focus on environmental risks and migration: causes and consequences

NASA Astrophysics Data System (ADS)

Adger, W. Neil; Arnell, Nigel W.; Black, Richard; Dercon, Stefan; Geddes, Andrew; Thomas, David S. G.

2015-06-01

Environmental change poses risks to societies, including disrupting social and economic systems such as migration. At the same time, migration is an effective adaptation to environmental and other risks. We review novel science on interactions between migration, environmental risks and climate change. We highlight emergent findings, including how dominant flows of rural to urban migration mean that populations are exposed to new risks within destination areas and the requirement for urban sustainability. We highlight the issue of lack of mobility as a major issue limiting the effectiveness of migration as an adaptation strategy and leading to potentially trapped populations. The paper presents scenarios of future migration that show both displacement and trapped populations over the incoming decades. Papers in the special issue bring new insights from demography, human geography, political science and environmental science to this emerging field.

Potential of Zero Charge and Its Temperature Derivative for Au(111) Electrode|Alkanethiol SAM|1.0 M Aqueous Electrolyte Solution Interfaces: Impact of Electrolyte Solution Ionic Strength and Its Effect on the Structure of the Modified Electrode|Electrolyte Solution Interface

DOE PAGES

Smalley, John F.

2017-04-06

In this study, we demonstrate how small and rapid temperature perturbations (produced by the indirect laser-induced temperature jump (ILIT) technique) of solid metal electrode|electrolyte solution interfaces may be used to determine the potential of zero (total) charge (E pzc) and its temperature derivativemore » $$\\left(\\frac{dEpzc}{dT}\\right)$$ of Au(111) electrode surfaces modified by alkanethiol self-assembled monolayers in contact with high ionic strength (i.e., 1.0 M) aqueous electrolyte solutions. The E pzc’s measured for two different types of SAMs (made from either HS(CH 2) n-1CH 3 (5 ≤ n ≤ 12, E pzc = -(0.99 ± 0.12) V vs SSCE) or HS(CH 2) nOH (3 ≤ n ≤ 16, E pzc = (0.46 ± 0.22) V vs SSCE)) are considerably different than those measured previously at much lower electrolyte solution ionic strengths. For mixed monolayers made from both HS(CH 2) n-1CH 3 and HS(CH 2) nFc (where Fc refers to ferrocene), the difference in Epzc decreases as a function of the surface concentration of the Fc moiety (i.e., [Fc]), and it completely disappears at a surprisingly small [Fc] (~4.0 × 10 –11 mol cm –2). These observations for the Au(111)|hydrophobic (neat and mixed) SAM|aqueous electrolyte solution interfaces, along with the surface potentials (g Sml(dip)) evaluated for the contacting electrolyte solution surfaces of these interfaces, are consistent with a structure for the water molecule components of these surfaces where there is a net orientation of the dipoles of these molecules. Accordingly, the negative (oxygen) ends of these molecules point toward the SAM surface. The positive values of g Sml(dip) evaluated for hydrophilic SAM (e.g., made from HS(CH 2) nOH)|aqueous electrolyte solution interfaces) also indicate that the structure of these interfaces is similar to that of the hydrophobic interfaces. However, g Sml(dip) decreases with increasing ionic strength for the hydrophilic interfaces, while it increases with increasing ionic strength for the hydrophobic interfaces. The data (and calculations) reported in the present work and other studies of hydrophobic (and hydrophilic)|aqueous solution interfaces are as yet insufficient to support a complete explanation for the effects of ionic strength observed in the present study. Nevertheless, an analysis based upon the value of $$\\left(\\frac{dEpzc}{dT}\\right)$$ (= (0.51 ± 0.12) mV/K, essentially the same for SAMs made from both HS(CH 2) n-1CH 3 and HS(CH 2) nOH), determined in the present study provides a further indication that upon formation of the SAM there is a partial charge transfer of electrons from the relevant gold atoms on the Au(111) surface to the sulfur atoms of the alkanethiols.« less

Characterizing the International Migration Barriers with a Probabilistic Multilateral Migration Model

PubMed Central

Li, Xiaomeng; Xu, Hongzhong; Chen, Jiawei; Chen, Qinghua; Zhang, Jiang; Di, Zengru

2016-01-01

Human migration is responsible for forming modern civilization and has had an important influence on the development of various countries. There are many issues worth researching, and “the reason to move” is the most basic one. The concept of migration cost in the classical self-selection theory, which was introduced by Roy and Borjas, is useful. However, migration cost cannot address global migration because of the limitations of deterministic and bilateral choice. Following the idea of migration cost, this paper developed a new probabilistic multilateral migration model by introducing the Boltzmann factor from statistical physics. After characterizing the underlying mechanism or driving force of human mobility, we reveal some interesting facts that have provided a deeper understanding of international migration, such as the negative correlation between migration costs for emigrants and immigrants and a global classification with clear regional and economic characteristics, based on clustering of migration cost vectors. In addition, we deconstruct the migration barriers using regression analysis and find that the influencing factors are complicated but can be partly (12.5%) described by several macro indexes, such as the GDP growth of the destination country, the GNI per capita and the HDI of both the source and destination countries. PMID:27597319

Characterizing the International Migration Barriers with a Probabilistic Multilateral Migration Model

NASA Astrophysics Data System (ADS)

Li, Xiaomeng; Xu, Hongzhong; Chen, Jiawei; Chen, Qinghua; Zhang, Jiang; di, Zengru

2016-09-01

Human migration is responsible for forming modern civilization and has had an important influence on the development of various countries. There are many issues worth researching, and “the reason to move” is the most basic one. The concept of migration cost in the classical self-selection theory, which was introduced by Roy and Borjas, is useful. However, migration cost cannot address global migration because of the limitations of deterministic and bilateral choice. Following the idea of migration cost, this paper developed a new probabilistic multilateral migration model by introducing the Boltzmann factor from statistical physics. After characterizing the underlying mechanism or driving force of human mobility, we reveal some interesting facts that have provided a deeper understanding of international migration, such as the negative correlation between migration costs for emigrants and immigrants and a global classification with clear regional and economic characteristics, based on clustering of migration cost vectors. In addition, we deconstruct the migration barriers using regression analysis and find that the influencing factors are complicated but can be partly (12.5%) described by several macro indexes, such as the GDP growth of the destination country, the GNI per capita and the HDI of both the source and destination countries.

Proactive Fault Tolerance for HPC with Xen Virtualization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagarajan, Arun Babu; Mueller, Frank; Engelmann, Christian

2007-01-01

with thousands of processors. At such large counts of compute nodes, faults are becoming common place. Current techniques to tolerate faults focus on reactive schemes to recover from faults and generally rely on a checkpoint/restart mechanism. Yet, in today's systems, node failures can often be anticipated by detecting a deteriorating health status. Instead of a reactive scheme for fault tolerance (FT), we are promoting a proactive one where processes automatically migrate from “unhealthy” nodes to healthy ones. Our approach relies on operating system virtualization techniques exemplied by but not limited to Xen. This paper contributes an automatic and transparent mechanismmore » for proactive FT for arbitrary MPI applications. It leverages virtualization techniques combined with health monitoring and load-based migration. We exploit Xen's live migration mechanism for a guest operating system (OS) to migrate an MPI task from a health-deteriorating node to a healthy one without stopping the MPI task during most of the migration. Our proactive FT daemon orchestrates the tasks of health monitoring, load determination and initiation of guest OS migration. Experimental results demonstrate that live migration hides migration costs and limits the overhead to only a few seconds making it an attractive approach to realize FT in HPC systems. Overall, our enhancements make proactive FT a valuable asset for long-running MPI application that is complementary to reactive FT using full checkpoint/ restart schemes since checkpoint frequencies can be reduced as fewer unanticipated failures are encountered. In the context of OS virtualization, we believe that this is the rst comprehensive study of proactive fault tolerance where live migration is actually triggered by health monitoring.« less

East with the night: longitudinal migration of the Orinoco goose (Neochen jubata) between Manú National Park, Peru and the Llanos de Moxos, Bolivia.

PubMed

Davenport, Lisa C; Nole Bazán, Inés; Carlos Erazo, Nancy

2012-01-01

We report on the intra-Amazonian migration of a pair of Orinoco Geese (Neochen jubata) from Manú National Park, Peru. The species is Critically Endangered in Peru, so a major aim of the study was to aid conservation planning by learning the wet season location of the country's last known breeding population. We captured a breeding pair on October 27, 2010, and fitted the birds with Microwave Telemetry, Inc. GPS/Argos satellite PTT's. The pair migrated ∼655 km from Manú National Park to the Llanos de Moxos, Bolivia (Dept. of Bení) in a predominantly longitudinal migration, reaching their final destination on December 23, 2010. Major movements (>5 km per time period) were almost exclusively at night and were undertaken with and without moonlight. Foraging areas used at stopovers in the Llanos de Moxos were remarkably limited, suggesting the importance of grazing lawns maintained by the geese and other herbivores, possibly including cattle. Orinoco Geese are resident in the Llanos de Moxos year-round, so the Manú geese represent a partial migration from the Bení region. We hypothesize that cavity nest limitation explains the partial migration of Orinoco Geese from the Llanos de Moxos.

East with the Night: Longitudinal Migration of the Orinoco Goose (Neochen jubata) between Manú National Park, Peru and the Llanos de Moxos, Bolivia

PubMed Central

Davenport, Lisa C.; Nole Bazán, Inés; Carlos Erazo, Nancy

2012-01-01

We report on the intra-Amazonian migration of a pair of Orinoco Geese (Neochen jubata) from Manú National Park, Peru. The species is Critically Endangered in Peru, so a major aim of the study was to aid conservation planning by learning the wet season location of the country's last known breeding population. We captured a breeding pair on October 27, 2010, and fitted the birds with Microwave Telemetry, Inc. GPS/Argos satellite PTT's. The pair migrated ∼655 km from Manú National Park to the Llanos de Moxos, Bolivia (Dept. of Bení) in a predominantly longitudinal migration, reaching their final destination on December 23, 2010. Major movements (>5 km per time period) were almost exclusively at night and were undertaken with and without moonlight. Foraging areas used at stopovers in the Llanos de Moxos were remarkably limited, suggesting the importance of grazing lawns maintained by the geese and other herbivores, possibly including cattle. Orinoco Geese are resident in the Llanos de Moxos year-round, so the Manú geese represent a partial migration from the Bení region. We hypothesize that cavity nest limitation explains the partial migration of Orinoco Geese from the Llanos de Moxos. PMID:23056512

Hinge-line Migration of Petermann Gletscher, North Greenland, Detected Using Satellite Radar Interferometry

NASA Technical Reports Server (NTRS)

Rignot, Eric

1998-01-01

The synthetic-aperture radar interferometry technique is used to detect the migration of the limit of tidal flexing, or hinge line, of the floating ice tongue of Petermann Gletscher, a major outlet glacier of north Greenland.

CAPILLARY ELECTROPHORESIS/LASER-INDUCED FLUORESCENCE DETECTION OF FLUORESCEIN AS A GROUNDWATER MIGRATION TRACER

EPA Science Inventory

Capillary electrophoresis (CE) has been applied to the determination of the groundwater migration tracer dye fluorescein based on laser-induced fluorescence (LIF) detection and compared to determinations obtained with traditional spectrofluorimetry. Detection limits of injected d...

Control of Subsurface Contaminant Migration by Vertical Engineered Barriers

EPA Science Inventory

This Fact Sheet is intended to provide remedial project managers (RPMs), on-scene coordinators (OSCs), contractors, and other remediation stakeholders with a basic overview of hazardous waste containment systems constructed to prevent or limit the migration of contamination in gr...

Improving the performances of autofocus based on adaptive retina-like sampling model

NASA Astrophysics Data System (ADS)

Hao, Qun; Xiao, Yuqing; Cao, Jie; Cheng, Yang; Sun, Ce

2018-03-01

An adaptive retina-like sampling model (ARSM) is proposed to balance autofocusing accuracy and efficiency. Based on the model, we carry out comparative experiments between the proposed method and the traditional method in terms of accuracy, the full width of the half maxima (FWHM) and time consumption. Results show that the performances of our method are better than that of the traditional method. Meanwhile, typical autofocus functions, including sum-modified-Laplacian (SML), Laplacian (LAP), Midfrequency-DCT (MDCT) and Absolute Tenengrad (ATEN) are compared through comparative experiments. The smallest FWHM is obtained by the use of LAP, which is more suitable for evaluating accuracy than other autofocus functions. The autofocus function of MDCT is most suitable to evaluate the real-time ability.

Gender and climate change-induced migration: proposing a framework for analysis

NASA Astrophysics Data System (ADS)

Chindarkar, Namrata

2012-06-01

This paper proposes frameworks to analyze the gender dimensions of climate change-induced migration. The experiences, needs and priorities of climate migrants will vary by gender and these differences need to be accounted for if policies are to be inclusive. Among the vulnerable groups, women are likely to be disproportionately affected due to climate change because on average women tend to be poorer, less educated, have a lower health status and have limited direct access to or ownership of natural resources. Both the process (actual movement) and the outcomes (rural-rural or rural-urban migration, out-migration mainly of men) of climate change-induced migration are also likely to be highly gendered.

PET bottle use patterns and antimony migration into bottled water and soft drinks: the case of British and Nigerian bottles.

PubMed

Tukur, Aminu; Sharp, Liz; Stern, Ben; Tizaoui, Chedly; Benkreira, Hadj

2012-04-01

While antimony has been reported to migrate from PET bottles into contents, reports on bottled water and soft drinks usage and PET bottle reuse patterns are currently unavailable in the literature. Bottle use conditions and patterns are important determinants of antimony migration. In this work a survey assessing the pattern of bottle use and reuse in Britain and Nigeria was undertaken. The survey findings influenced the design of laboratory experiments that assessed the migration of antimony from PET bottles into water and soft drinks. Typical storage durations for bottled contents between purchase and opening for use were 7 days or less. However storage of up to one year was reported. Bottle reuse was high and similar for the two countries with reuse durations being higher in Nigeria. The antimony concentration in 32 PET bottle materials from Britain and Nigeria were similar and ranged between 177 and 310 mg kg(-1). For 47 freshly purchased British bottled contents antimony concentration ranged between 0.03 and 6.61 μg L(-1) with only one sample exceeding the EU acceptable limit. Concentrations of Cd, Ge, Zn, Al, Be, Ti, Co and Pb were also measured. At realistic temperatures of 40 and 60 °C antimony concentration in deionised water in bottles remained below the EU acceptable limit even after 48 h exposure. The limit was exceeded for most exposures at 80 °C. Concentration of antimony in some bottled contents exceeded the EU limit after 11 months of storage at room temperature. Bottle aging and increase in bottle volume were associated with decreased migration of antimony from bottles.

Reverse time migration by Krylov subspace reduced order modeling

NASA Astrophysics Data System (ADS)

Basir, Hadi Mahdavi; Javaherian, Abdolrahim; Shomali, Zaher Hossein; Firouz-Abadi, Roohollah Dehghani; Gholamy, Shaban Ali

2018-04-01

Imaging is a key step in seismic data processing. To date, a myriad of advanced pre-stack depth migration approaches have been developed; however, reverse time migration (RTM) is still considered as the high-end imaging algorithm. The main limitations associated with the performance cost of reverse time migration are the intensive computation of the forward and backward simulations, time consumption, and memory allocation related to imaging condition. Based on the reduced order modeling, we proposed an algorithm, which can be adapted to all the aforementioned factors. Our proposed method benefit from Krylov subspaces method to compute certain mode shapes of the velocity model computed by as an orthogonal base of reduced order modeling. Reverse time migration by reduced order modeling is helpful concerning the highly parallel computation and strongly reduces the memory requirement of reverse time migration. The synthetic model results showed that suggested method can decrease the computational costs of reverse time migration by several orders of magnitudes, compared with reverse time migration by finite element method.

Resolving ultrafast exciton migration in organic solids at the nanoscale.

PubMed

Penwell, Samuel B; Ginsberg, Lucas D S; Noriega, Rodrigo; Ginsberg, Naomi S

2017-11-01

Effectiveness of molecular-based light harvesting relies on transport of excitons to charge-transfer sites. Measuring exciton migration, however, has been challenging because of the mismatch between nanoscale migration lengths and the diffraction limit. Instead of using bulk substrate quenching methods, here we define quenching boundaries all-optically with sub-diffraction resolution, thus characterizing spatiotemporal exciton migration on its native nanometre and picosecond scales. By transforming stimulated emission depletion microscopy into a time-resolved ultrafast approach, we measure a 16-nm migration length in poly(2,5-di(hexyloxy)cyanoterephthalylidene) conjugated polymer films. Combined with Monte Carlo exciton hopping simulations, we show that migration in these films is essentially diffusive because intrinsic chromophore energetic disorder is comparable to chromophore inhomogeneous broadening. Our approach will enable previously unattainable correlation of local material structure to exciton migration character, applicable not only to photovoltaic or display-destined organic semiconductors but also to explaining the quintessential exciton migration exhibited in photosynthesis.

INFLUENCE OF STRATIGRAPHY ON A DIVING MTBE PLUME AND ITS CHARACTERIZATION: A CASE STUDY

EPA Science Inventory

Conventional conceptual models applied at petroleum release sites are often based on assumptions of vertical contaminant migration through the vadose zone followed by horizontal, downgradient transport at the water table with limited, if any, additional downward migration. Howev...

Simultaneous determination of 17 sulfonamides and the potentiators ormetoprim and trimethoprim in salmon muscle by liquid chromatography with tandem mass spectrometry detection.

PubMed

Potter, Ross A; Burns, B Garth; van de Riet, Jeffrey M; North, David H; Darvesh, Rozina

2007-01-01

A simple, robust method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of 17 sulfonamides [sulfanilamide (SNL), sulfacetamide (SAA), sulfaguanidine (SGD), sulfapyridine (SPY), sulfadiazine (SDZ), sulfathiazole (STZ), sulfamerazine (SMR), sulfamethoxazole (SOZ), sulfamoxole (SXL), sulfisoxazole (SXZ), sulfamethizole (SML), sulfamethazine (SMZ), sulfamethoxypyridazine (SMP), sulfamonomethoxine (SMM), sulfachloropyridazine (SCP), sulfaquinoxaline (SQX), and sulfadimethoxine (SDM)] and 2 potentiators [ormetoprim (OMP) and trimethoprim (TMP)] in fish tissue has been developed. The analytes were extracted from homogenized fish tissue with water-acetonitrile (50 + 50). The extract was clarified by centrifugation and a portion defatted with hexane. The analytes were partitioned into chloroform and evaporated to dryness. The redissolved residue was applied to a C18 reversed-phase column with a water-acetonitrile (0.1% acetic acid) gradient. All of the compounds were completely separated and detected in <10 min at 30 degrees C using LC/MS/MS. Standard curves were linear over the range of 0.02 to 5 ng injected. The limit of detection varied from 0.1 ng/g for SMZ and OMP to 0.9 ng/g for SXL and SOZ. Recoveries varied from 100% for SDM, SOZ, and SQX and 85% for SMR, OMP, and TMP to approximately 30% for SAA. Relative standard deviations for repeat analysis varied from 4% for SMZ and SCP to 23% for SAA.

Apparatus and method for time-integrated, active sampling of contaminants in fluids demonstrated by monitoring of hexavalent chromium in groundwater.

PubMed

Roll, Isaac B; Driver, Erin M; Halden, Rolf U

2016-06-15

Annual U.S. expenditures of $2B for site characterization invite the development of new technologies to improve data quality while reducing costs and minimizing uncertainty in groundwater monitoring. This work presents a new instrument for time-integrated sampling of environmental fluids using in situ solid-phase extraction (SPE). The In Situ Sampler (IS2) is an automated submersible device capable of extracting dissolved contaminants from water (100s-1000smL) over extended periods (hours to weeks), retaining the analytes, and rejecting the processed fluid. A field demonstration of the IS2 revealed 28-day average concentration of hexavalent chromium in a shallow aquifer affected by tidal stresses via sampling of groundwater as both liquid and sorbed composite samples, each obtained in triplicate. In situ SPE exhibited 75±6% recovery and an 8-fold improvement in reporting limit. Relative to use of conventional methods (100%), beneficial characteristics of the device and method included minimal hazardous material generation (2%), transportation cost (10%), and associated carbon footprint (2%). The IS2 is compatible with commercial SPE resins and standard extraction methods, and has been certified for more general use (i.e., inorganics and organics) by the Environmental Security Technology Certification Program (ESTCP) of the U.S. Department of Defense. Copyright © 2016 Elsevier B.V. All rights reserved.

Relative importance of moisture migration and amylopectin retrogradation for pound cake crumb firming.

PubMed

Luyts, A; Wilderjans, E; Van Haesendonck, I; Brijs, K; Courtin, C M; Delcour, J A

2013-12-15

Moisture migration largely impacts cake crumb firmness during storage at ambient temperature. To study the importance of phenomena other than crumb to crust moisture migration and to exclude moisture and temperature gradients during baking, crustless cakes were baked using an electrical resistance oven (ERO). Cake crumb firming was evaluated by texture analysis. First, ERO cakes with properties similar to those baked conventionally were produced. Cake batter moisture content (MC) was adjusted to ensure complete starch gelatinisation in the baking process. In cakes baked conventionally, most of the increase in crumb firmness during storage was caused by moisture migration. Proton nuclear magnetic resonance ((1)H NMR) showed that the population containing protons of crystalline starch grew during cake storage. These and differential scanning calorimetry (DSC) data pointed to only limited amylopectin retrogradation. The limited increase in amylopectin retrogradation during cake storage cannot solely account for the significant firming of ERO cakes and, hence, other phenomena are involved in cake firming. Copyright © 2013 Elsevier Ltd. All rights reserved.

An insight on acyl migration in solvent-free ethanolysis of model triglycerides using Novozym 435.

PubMed

Sánchez, Daniel Alberto; Tonetto, Gabriela Marta; Ferreira, María Luján

2016-02-20

In this work, the ethanolysis of triglycerides catalyzed by immobilized lipase was studied, focusing on the secondary reaction of acyl migration. The catalytic tests were performed in a solvent-free reaction medium using Novozym 435 as biocatalyst. The selected experimental variables were biocatalyst loading (5-20mg), reaction time (30-90min), and chain length of the fatty acids in triglycerides with and without unsaturation (short (triacetin), medium (tricaprylin) and long (tripalmitin/triolein)). The formation of 2-monoglyceride by ethanolysis of triglycerides was favored by long reaction times and large biocatalyst loading with saturated short- to medium-chain triglycerides. In the case of long-chain triglycerides, the formation of this monoglyceride was widely limited by acyl migration. In turn, acyl migration increased the yield of ethyl esters and minimized the content of monoglycerides and diglycerides. Thus, the enzymatic synthesis of biodiesel was favored by long-chain triglycerides (which favor the acyl migration), long reaction times and large biocatalyst loading. The conversion of acylglycerides made from long-chain fatty acids with unsaturation was relatively low due to limitations in their access to the active site of the lipase. Copyright © 2016 Elsevier B.V. All rights reserved.

Difficult decisions: Migration from Small Island Developing States under climate change

NASA Astrophysics Data System (ADS)

Kelman, Ilan

2015-04-01

The impacts of climate change on Small Island Developing States (SIDS) are leading to discussions regarding decision-making about the potential need to migrate. Despite the situation being well-documented, with many SIDS aiming to raise the topic to prominence and to take action for themselves, limited support and interest has been forthcoming from external sources. This paper presents, analyzes, and critiques a decision-making flowchart to support actions for SIDS dealing with climate change-linked migration. The flowchart contributes to identifying the pertinent topics to consider and the potential support needed to implement decision-making. The flowchart has significant limitations and there are topics which it cannot resolve. On-the-ground considerations include who decides, finances, implements, monitors, and enforces each decision. Additionally, views within communities differ, hence mechanisms are needed for dealing with differences, while issues to address include moral and legal blame for any climate change-linked migration, the ultimate goal of the decision-making process, the wider role of migration in SIDS communities and the right to judge decision-making and decisions. The conclusions summarize the paper, emphasizing the importance of considering contexts beyond climate change and multiple SIDS voices.

Human exposure assessment of silver and copper migrating from an antimicrobial nanocoated packaging material into an acidic food simulant.

PubMed

Hannon, Joseph Christopher; Kerry, Joseph P; Cruz-Romero, Malco; Azlin-Hasim, Shafrina; Morris, Michael; Cummins, Enda

2016-09-01

To examine the human exposure to a novel silver and copper nanoparticle (AgNP and CuNP)/polystyrene-polyethylene oxide block copolymer (PS-b-PEO) food packaging coating, the migration of Ag and Cu into 3% acetic acid (3% HAc) food simulant was assessed at 60 °C for 10 days. Significantly lower migration was observed for Ag (0.46 mg/kg food) compared to Cu (0.82 mg/kg food) measured by inductively coupled plasma - atomic emission spectrometry (ICP-AES). In addition, no distinct population of AgNPs or CuNPs were observed in 3% HAc by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). The predicted human exposure to Ag and Cu was used to calculate a margin of exposure (MOE) for ionic species of Ag and Cu, which indicated the safe use of the food packaging in a hypothetical scenario (e.g. as fruit juice packaging). While migration exceeded regulatory limits, the calculated MOE suggests current migration limits may be conservative for specific nano-packaging applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bird species migration ratio in East Asia, Australia, and surrounding islands.

PubMed

Kuo, Yiliang; Lin, Da-Li; Chuang, Fu-Man; Lee, Pei-Fen; Ding, Tzung-Su

2013-08-01

Bird migration and its relationship with the contemporary environment have attracted long-term discussion. We calculated the avian migration ratio (the proportion of breeding species that migrate) in the areas from 70°E to 180°E and examined its relationship with the annual ranges of ambient temperature, primary productivity (estimated by the Enhanced Vegetation Index), and precipitation, along with island isolation and elevational range. The avian migration ratio increased with increasing latitude in general but varied greatly between the two hemispheres. Additionally, it showed minimal differences between continents and islands. Our analyses revealed that the seasonality of ambient temperature, which represents the energy expenditure of birds, is the dominant factor in determining bird species migration. Seasonality in primary productivity and other environmental factors play an indirect or limited role in bird species migration. The lower avian migration ratio in the Southern Hemisphere can be attributed to its paleogeographical isolation, stable paleoclimate, and warm contemporary environment. Under current trends of global warming, our findings should lead to further studies of the impact of warming on bird migration.

Bird species migration ratio in East Asia, Australia, and surrounding islands

NASA Astrophysics Data System (ADS)

Kuo, Yiliang; Lin, Da-Li; Chuang, Fu-Man; Lee, Pei-Fen; Ding, Tzung-Su

2013-08-01

Bird migration and its relationship with the contemporary environment have attracted long-term discussion. We calculated the avian migration ratio (the proportion of breeding species that migrate) in the areas from 70°E to 180°E and examined its relationship with the annual ranges of ambient temperature, primary productivity (estimated by the Enhanced Vegetation Index), and precipitation, along with island isolation and elevational range. The avian migration ratio increased with increasing latitude in general but varied greatly between the two hemispheres. Additionally, it showed minimal differences between continents and islands. Our analyses revealed that the seasonality of ambient temperature, which represents the energy expenditure of birds, is the dominant factor in determining bird species migration. Seasonality in primary productivity and other environmental factors play an indirect or limited role in bird species migration. The lower avian migration ratio in the Southern Hemisphere can be attributed to its paleogeographical isolation, stable paleoclimate, and warm contemporary environment. Under current trends of global warming, our findings should lead to further studies of the impact of warming on bird migration.

46 CFR 148.450 - Cargoes subject to liquefaction.

Code of Federal Regulations, 2013 CFR

2013-10-01

... in this section— (1) Cargo subject to liquefaction means a material that is subject to moisture migration and subsequent liquefaction if shipped with moisture content in excess of the transportable moisture limit. (2) Moisture migration is the movement of moisture by settling and consolidation of a...

46 CFR 148.450 - Cargoes subject to liquefaction.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in this section— (1) Cargo subject to liquefaction means a material that is subject to moisture migration and subsequent liquefaction if shipped with moisture content in excess of the transportable moisture limit. (2) Moisture migration is the movement of moisture by settling and consolidation of a...

46 CFR 148.450 - Cargoes subject to liquefaction.

Code of Federal Regulations, 2012 CFR

2012-10-01

... in this section— (1) Cargo subject to liquefaction means a material that is subject to moisture migration and subsequent liquefaction if shipped with moisture content in excess of the transportable moisture limit. (2) Moisture migration is the movement of moisture by settling and consolidation of a...

The structured ancestral selection graph and the many-demes limit.

PubMed

Slade, Paul F; Wakeley, John

2005-02-01

We show that the unstructured ancestral selection graph applies to part of the history of a sample from a population structured by restricted migration among subpopulations, or demes. The result holds in the limit as the number of demes tends to infinity with proportionately weak selection, and we have also made the assumptions of island-type migration and that demes are equivalent in size. After an instantaneous sample-size adjustment, this structured ancestral selection graph converges to an unstructured ancestral selection graph with a mutation parameter that depends inversely on the migration rate. In contrast, the selection parameter for the population is independent of the migration rate and is identical to the selection parameter in an unstructured population. We show analytically that estimators of the migration rate, based on pairwise sequence differences, derived under the assumption of neutrality should perform equally well in the presence of weak selection. We also modify an algorithm for simulating genealogies conditional on the frequencies of two selected alleles in a sample. This permits efficient simulation of stronger selection than was previously possible. Using this new algorithm, we simulate gene genealogies under the many-demes ancestral selection graph and identify some situations in which migration has a strong effect on the time to the most recent common ancestor of the sample. We find that a similar effect also increases the sensitivity of the genealogy to selection.

The impact of small irrigation diversion dams on the recent migration rates of steelhead and redband trout (Oncorhynchus mykiss)

USGS Publications Warehouse

Weigel, Dana E.; Connolly, Patrick J.; Powell, Madison S.

2013-01-01

Barriers to migration are numerous in stream environments and can occur from anthropogenic activities (such as dams and culverts) or natural processes (such as log jams or dams constructed by beaver (Castor canadensis)). Identification of barriers can be difficult when obstructions are temporary or incomplete providing passage periodically. We examine the effect of several small irrigation diversion dams on the recent migration rates of steelhead (Oncorhynchus mykiss) in three tributaries to the Methow River, Washington. The three basins had different recent migration patterns: Beaver Creek did not have any recent migration between sites, Libby Creek had two-way migration between sites and Gold Creek had downstream migration between sites. Sites with migration were significantly different from sites without migration in distance, number of obstructions, obstruction height to depth ratio and maximum stream gradient. When comparing the sites without migration in Beaver Creek to the sites with migration in Libby and Gold creeks, the number of obstructions was the only significant variable. Multinomial logistic regression identified obstruction height to depth ratio and maximum stream gradient as the best fitting model to predict the level of migration among sites. Small irrigation diversion dams were limiting population interactions in Beaver Creek and collectively blocking steelhead migration into the stream. Variables related to stream resistance (gradient, obstruction number and obstruction height to depth ratio) were better predictors of recent migration rates than distance, and can provide important insight into migration and population demographic processes in lotic species.

Optimal migration energetics of humpback whales and the implications of disturbance.

PubMed

Braithwaite, Janelle E; Meeuwig, Jessica J; Hipsey, Matthew R

2015-01-01

Whales migrate long distances and reproduce on a finite store of energy. Budgeting the use of this limited energy reserve is an important factor to ensure survival over the period of migration and to maximize reproductive investment. For some whales, migration routes are closely associated with coastal areas, exposing animals to high levels of human activity. It is currently unclear how various forms of human activity may disturb whales during migration, how this might impact their energy balance and how this could translate into long-term demographic changes. Here, we develop a theoretical bioenergetic model for migrating humpback whales to investigate the optimal migration strategy that minimizes energy use. The average migration velocity was an important driver of the total energy used by a whale, and an optimal velocity of 1.1 m s(-1) was determined. This optimal velocity is comparable to documented observed migration speeds, suggesting that whales migrate at a speed that conserves energy. Furthermore, the amount of resting time during migration was influenced by both transport costs and feeding rates. We simulated hypothetical disturbances to the optimal migration strategy in two ways, by altering average velocity to represent changes in behavioural activity and by increasing total travelled distance to represent displacement along the migration route. In both cases, disturbance increased overall energy use, with implications for the growth potential of calves.

Optimal migration energetics of humpback whales and the implications of disturbance

PubMed Central

Braithwaite, Janelle E.; Meeuwig, Jessica J.; Hipsey, Matthew R.

2015-01-01

Whales migrate long distances and reproduce on a finite store of energy. Budgeting the use of this limited energy reserve is an important factor to ensure survival over the period of migration and to maximize reproductive investment. For some whales, migration routes are closely associated with coastal areas, exposing animals to high levels of human activity. It is currently unclear how various forms of human activity may disturb whales during migration, how this might impact their energy balance and how this could translate into long-term demographic changes. Here, we develop a theoretical bioenergetic model for migrating humpback whales to investigate the optimal migration strategy that minimizes energy use. The average migration velocity was an important driver of the total energy used by a whale, and an optimal velocity of 1.1 m s−1 was determined. This optimal velocity is comparable to documented observed migration speeds, suggesting that whales migrate at a speed that conserves energy. Furthermore, the amount of resting time during migration was influenced by both transport costs and feeding rates. We simulated hypothetical disturbances to the optimal migration strategy in two ways, by altering average velocity to represent changes in behavioural activity and by increasing total travelled distance to represent displacement along the migration route. In both cases, disturbance increased overall energy use, with implications for the growth potential of calves. PMID:27293686

Assessment of epoxidized soy bean oil (ESBO) migrating into foods: comparison with ESBO-like epoxy fatty acids in our normal diet.

PubMed

Fankhauser-Noti, Anja; Fiselier, Katell; Biedermann-Brem, Sandra; Grob, Koni

2006-08-01

Epoxidized soy bean oil (ESBO) was found to be toxic for rats, but the toxic constituent is unknown. It became an issue as the migration from the gaskets in the lids for jars into oily foods regularly far exceeds the European legal limit (overall migration limit and specific migration limit derived from the tolerable daily intake (TDI)). In the context of risk management it was of interest to determine the epoxidized fatty acids of ESBO in those foods of our normal diet which are expected to contain the highest concentrations, i.e., oxidized edible oils (including degraded frying oils), fried foods, bakery ware and roasted meat. The contribution of epoxy oleic acid from ESBO to our diet turned out to be negligible. If this acid were the toxic component in ESBO, the toxicological assessment would primarily be a warning regarding oxidized fats and oils. The contribution of diepoxy linoleic acid from ESBO might be similar to the exposure from oxidized fats and oils of our diet, whereas the intake of triepoxy linolenic acid from ESBO exceeds that from normal food by around two orders of magnitude. Hence use of an epoxidized edible oil virtually free of linolenic acid would be inconspicuous in our diet.

Negotiating Potentials and Limitations in Education in Transnational Migration Contexts: A Case Study

ERIC Educational Resources Information Center

Chamakalayil, Lalitha; Riegel, Christine

2016-01-01

Education systems reproduce social inequality based on social class, gender, and minority ethnicity ascriptions, and are organized along national structures. This paper explores, how migration and international mobility shape an individuals scope of possibilities in the context of education. We analyze how societal and institutional possibilities…

"Nervios" and "Modern Childhood": Migration and Shifting Contexts of Child Life in the Ecuadorian Andes.

ERIC Educational Resources Information Center

Pribilsky, Jason

2001-01-01

Argues that beyond explanations predicated on psychological ideas of separation and attachment, "nervios," a depression-like disorder among children in the southern Ecuadorian Andes, reflects the limits of children's abilities to accept terms of family life increasingly defined through transnational migration and new consumption…

The gravity model of labor migration behavior

NASA Astrophysics Data System (ADS)

Alexandr, Tarasyev; Alexandr, Tarasyev

2017-07-01

In this article, we present a dynamic inter-regional model, that is based on the gravity approach to migration and describes in continuous time the labor force dynamics between a number of conjugate regions. Our modification of the gravity migration model allows to explain the migration processes and to display the impact of migration on the regional economic development both for regions of origin and attraction. The application of our model allows to trace the dependency between salaries levels, total workforce, the number of vacancies and the number unemployed people in simulated regions. Due to the gravity component in our model the accuracy of prediction for migration flows is limited by the distance range between analyzed regions, so this model is tested on a number of conjugate neighbor regions. Future studies will be aimed at development of a multi-level dynamic model, which allows to construct a forecast for unemployment and vacancies trends on the first modeling level and to use these identified parameters on the second level for describing dynamic trajectories of migration flows.

Comments in reply: new directions in migration research.

PubMed

Shaw, R P

1986-01-01

The author comments on a review of his recent book NEW DIRECTIONS IN MIGRATION RESEARCH and reflects on theory and model specification, problems of estimation and statistical inference, realities of temporal and spatial heterogeneity, choices of explanatory variables, and the importance of broader political issues in migration studies. A core hypothesis is that market forces have declined as influences on internal migration in Canada over the last 30 years. Theoretical underpinnings include declining relevance of wage considerations in the decision to migrate on the assumption that marginal utility of money diminishes and marginal utility of leisure increases as society becomes wealthier. The author perceives the human capital model to have limitations and is especially troubled by the "as if" clause--that all migrants behave "as if" they calculate benefits and risks with equal rigor. The author has "shadowed" and not quantified the costs involved. He implies that normative frameworks for future migration research and planning should be established.

Lead migration from toys by anodic stripping voltammetry using a bismuth film electrode.

PubMed

Leal, M Fernanda C; Catarino, Rita I L; Pimenta, Adriana M; Souto, M Renata S; Afonso, Christelle S; Fernandes, Ana F Q

2016-09-02

Metals may be released from toys via saliva during mouthing, via sweat during dermal contact, or via gastric and intestinal fluids after partial or whole ingestion. In this study, we determined the lead migration from toys bought on the Portuguese market for children below 3 years of age. The lead migration was performed according to the European Committee for Standardization EN 71-3, which proposes a 2-hour migration test that simulates human gastric conditions. The voltammetric determination of migrated lead was performed by anodic stripping voltammetry (ASV) at a bismuth film electrode (BiFE). For all the analyzed toys, the values of migrated lead did not exceed the limits imposed by the European Committee for Standardization EN 71-3 (90 mg kg -1 ) and by the EU Directive 2009/48/EC (13.5 mg kg -1 ) on the safety of toys.

Direct observations of American eels migrating across the continental shelf to the Sargasso Sea

PubMed Central

Béguer-Pon, Mélanie; Castonguay, Martin; Shan, Shiliang; Benchetrit, José; Dodson, Julian J.

2015-01-01

Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues. PMID:26505325

Nocturnal bird migration in opaque clouds

NASA Technical Reports Server (NTRS)

Griffin, D. R.

1972-01-01

The use of a tracking radar to measure the flight paths of migrating birds on nights with opaque clouds is discussed. The effects of wind and lack of visual references are examined. The limitations of the radar observations are described, and samples of tracks obtained during radar observations are included. It is concluded that nonvisual mechanisms of orientation make it possible for birds to migrate in opaque clouds, but the exact nature of the sensory information cannot be determined by radar observations.

Rural to urban migration is an unforeseen impact of development intervention in Ethiopia.

PubMed

Gibson, Mhairi A; Gurmu, Eshetu

2012-01-01

Rural development initiatives across the developing world are designed to improve community well-being and livelihoods. However they may also have unforeseen consequences, in some cases placing further demands on stretched public services. In this paper we use data from a longitudinal study of five Ethiopian villages to investigate the impact of a recent rural development initiative, installing village-level water taps, on rural to urban migration of young adults. Our previous research has identified that tap stands dramatically reduced child mortality, but were also associated with increased fertility. We demonstrate that the installation of taps is associated with increased rural-urban migration of young adults (15-30 years) over a 15 year period (15.5% migrate out, n = 1912 from 1280 rural households). Young adults with access to this rural development intervention had three times the relative risk of migrating to urban centres compared to those without the development. We also identify that family dynamics, specifically sibling competition for limited household resources (e.g. food, heritable land and marriage opportunities), are key to understanding the timing of out-migration. Birth of a younger sibling doubled the odds of out-migration and starting married life reduced it. Rural out-migration appears to be a response to increasing rural resource scarcity, principally competition for agricultural land. Strategies for livelihood diversification include education and off-farm casual wage-labour. However, jobs and services are limited in urban centres, few migrants send large cash remittances back to their families, and most return to their villages within one year without advanced qualifications. One benefit for returning migrants may be through enhanced social prestige and mate-acquisition on return to rural areas. These findings have wide implications for current understanding of the processes which initiate rural-to-urban migration and transitions to low fertility, as well as for the design and implementation of development intervention across the rural and urban developing world.

Rural to Urban Migration Is an Unforeseen Impact of Development Intervention in Ethiopia

PubMed Central

Gibson, Mhairi A.; Gurmu, Eshetu

2012-01-01

Rural development initiatives across the developing world are designed to improve community well-being and livelihoods. However they may also have unforeseen consequences, in some cases placing further demands on stretched public services. In this paper we use data from a longitudinal study of five Ethiopian villages to investigate the impact of a recent rural development initiative, installing village-level water taps, on rural to urban migration of young adults. Our previous research has identified that tap stands dramatically reduced child mortality, but were also associated with increased fertility. We demonstrate that the installation of taps is associated with increased rural-urban migration of young adults (15–30 years) over a 15 year period (15.5% migrate out, n = 1912 from 1280 rural households). Young adults with access to this rural development intervention had three times the relative risk of migrating to urban centres compared to those without the development. We also identify that family dynamics, specifically sibling competition for limited household resources (e.g. food, heritable land and marriage opportunities), are key to understanding the timing of out-migration. Birth of a younger sibling doubled the odds of out-migration and starting married life reduced it. Rural out-migration appears to be a response to increasing rural resource scarcity, principally competition for agricultural land. Strategies for livelihood diversification include education and off-farm casual wage-labour. However, jobs and services are limited in urban centres, few migrants send large cash remittances back to their families, and most return to their villages within one year without advanced qualifications. One benefit for returning migrants may be through enhanced social prestige and mate-acquisition on return to rural areas. These findings have wide implications for current understanding of the processes which initiate rural-to-urban migration and transitions to low fertility, as well as for the design and implementation of development intervention across the rural and urban developing world. PMID:23155400

Three-Dimensional Passive-Source Reverse-Time Migration of Converted Waves: The Method

NASA Astrophysics Data System (ADS)

Li, Jiahang; Shen, Yang; Zhang, Wei

2018-02-01

At seismic discontinuities in the crust and mantle, part of the compressional wave energy converts to shear wave, and vice versa. These converted waves have been widely used in receiver function (RF) studies to image discontinuity structures in the Earth. While generally successful, the conventional RF method has its limitations and is suited mostly to flat or gently dipping structures. Among the efforts to overcome the limitations of the conventional RF method is the development of the wave-theory-based, passive-source reverse-time migration (PS-RTM) for imaging complex seismic discontinuities and scatters. To date, PS-RTM has been implemented only in 2D in the Cartesian coordinate for local problems and thus has limited applicability. In this paper, we introduce a 3D PS-RTM approach in the spherical coordinate, which is better suited for regional and global problems. New computational procedures are developed to reduce artifacts and enhance migrated images, including back-propagating the main arrival and the coda containing the converted waves separately, using a modified Helmholtz decomposition operator to separate the P and S modes in the back-propagated wavefields, and applying an imaging condition that maintains a consistent polarity for a given velocity contrast. Our new approach allows us to use migration velocity models with realistic velocity discontinuities, improving accuracy of the migrated images. We present several synthetic experiments to demonstrate the method, using regional and teleseismic sources. The results show that both regional and teleseismic sources can illuminate complex structures and this method is well suited for imaging dipping interfaces and sharp lateral changes in discontinuity structures.

Population flows in an international context.

PubMed

Regulska, J; Vural, L

1987-01-01

The authors feel that geography courses have been remiss in examining migration in its international context and in discussing its global implications. They have constructed this 6-lecture teaching module that addresses the economic, political, and social ramifications of international migration, in addition to the geographical dimension. The module is geared to undergraduate studies in human, social, or population geography, sociology, economics, and political science. Each of the lectures outlined includes special topics for emphasis, supplementary audiovisual materials, and suggested readings. Lectures include: 1) The Importance and Global Effects of International Population Flows; 2) Guest Workers -- Migration of People with Limited Skills; 3) Brain Drain -- Migration of Highly Skilled Professionals; 4) Political Causes of International Migration: Refugee Movement; 5) Refugee Women -- Displaced Majority; and 6) Comparison of Immigration and Refugee Policy in the US and Canada.

Climate Variability and Inter-Provincial Migration in South America, 1970-2011

PubMed Central

Thiede, Brian; Gray, Clark; Mueller, Valerie

2016-01-01

We examine the effect of climate variability on human migration in South America. Our analyses draw on over 21 million observations of adults aged 15-40 from 25 censuses conducted in eight South American countries. Addressing limitations associated with methodological diversity among prior studies, we apply a common analytic approach and uniform definitions of migration and climate across all countries. We estimate the effects of climate variability on migration overall and also investigate heterogeneity across sex, age, and socioeconomic groups, across countries, and across historical climate conditions. We also disaggregate migration by the rural/urban status of destination. We find that exposure to monthly temperature shocks has the most consistent effects on migration relative to monthly rainfall shocks and gradual changes in climate over multi-year periods. We also find evidence of heterogeneity across demographic groups and countries. Analyses that disaggregate migration by the rural/urban status of destination suggest that much of the climate-related inter-province migration is directed toward urban areas. Overall, our results underscore the complexity of environment-migration linkages and challenge simplistic narratives that envision a linear and monolithic migratory response to changing climates. PMID:28413264

Climate Variability and Inter-Provincial Migration in South America, 1970-2011.

PubMed

Thiede, Brian; Gray, Clark; Mueller, Valerie

2016-11-01

We examine the effect of climate variability on human migration in South America. Our analyses draw on over 21 million observations of adults aged 15-40 from 25 censuses conducted in eight South American countries. Addressing limitations associated with methodological diversity among prior studies, we apply a common analytic approach and uniform definitions of migration and climate across all countries. We estimate the effects of climate variability on migration overall and also investigate heterogeneity across sex, age, and socioeconomic groups, across countries, and across historical climate conditions. We also disaggregate migration by the rural/urban status of destination. We find that exposure to monthly temperature shocks has the most consistent effects on migration relative to monthly rainfall shocks and gradual changes in climate over multi-year periods. We also find evidence of heterogeneity across demographic groups and countries. Analyses that disaggregate migration by the rural/urban status of destination suggest that much of the climate-related inter-province migration is directed toward urban areas. Overall, our results underscore the complexity of environment-migration linkages and challenge simplistic narratives that envision a linear and monolithic migratory response to changing climates.

Rural development and urban migration: can we keep them down on the farm?

PubMed

Rhoda, R

1983-01-01

This study tests the hypothesis that rural development projects and programs reduce rural-urban migration. The author presents various factors in the social theories of migration, including those relating to origin and destination, intervening obstacles such as distance, and personal factors. 3 economic models of migration are the human capital or cost-benefit approach, the expected income model, and the intersectoral linkage model. Empirical studies of migration indicate that: 1) rural areas with high rates of out-migration tend to have high population densities or high ratios of labor to arable land, 2) distance inhibits migration, 3) rural-urban migration is positively correlated with family income level, and 4) selectivity differences in socioeconomic status between migrants and nonmigrants often are grouped into development packages which might include irrigation, new varieties of seed, subsidized credit, increased extension, and improved marketing arrangements. The migration impacts of some of these efforts are described: 1) land reform usually is expected to slow rural out-migration because it normally increases labor utilization in rural areas, but this is a limited effect, 2) migration effects of the Green Revolution technology are mainly in rural-rural migration, and 3) agricultural mechanization may stimulate rural-urban migration in the long run. Development of rural social services migh have various effects on rural-urban migration. Better rural education, which improves the chances of urban employment, will stimulate rural-urban migration, while successful rural family planning programs will have a negative effect in the long run as there will be reduced population pressure on arable land. Better rural health services might reduce the incentive for rural-urban migration as well. It is suggested that governments reconsider policies which rely on rural development to curb rural-urban migration and alleviate problems of urban poverty and underemployment.

Faunal record identifies Bering isthmus conditions as constraint to end-Pleistocene migration to the New World

PubMed Central

Meiri, Meirav; Lister, Adrian M.; Collins, Matthew J.; Tuross, Noreen; Goebel, Ted; Blockley, Simon; Zazula, Grant D.; van Doorn, Nienke; Dale Guthrie, R.; Boeskorov, Gennady G.; Baryshnikov, Gennady F.; Sher, Andrei; Barnes, Ian

2014-01-01

Human colonization of the New World is generally believed to have entailed migrations from Siberia across the Bering isthmus. However, the limited archaeological record of these migrations means that details of the timing, cause and rate remain cryptic. Here, we have used a combination of ancient DNA, 14C dating, hydrogen and oxygen isotopes, and collagen sequencing to explore the colonization history of one of the few other large mammals to have successfully migrated into the Americas at this time: the North American elk (Cervus elaphus canadensis), also known as wapiti. We identify a long-term occupation of northeast Siberia, far beyond the species’s current Old World distribution. Migration into North America occurred at the end of the last glaciation, while the northeast Siberian source population became extinct only within the last 500 years. This finding is congruent with a similar proposed delay in human colonization, inferred from modern human mitochondrial DNA, and suggestions that the Bering isthmus was not traversable during parts of the Late Pleistocene. Our data imply a fundamental constraint in crossing Beringia, placing limits on the age and mode of human settlement in the Americas, and further establish the utility of ancient DNA in palaeontological investigations of species histories. PMID:24335981

Thermocapillary Bubble Migration: Thermal Boundary Layers for Large Marangoni Numbers

NASA Technical Reports Server (NTRS)

Balasubramaniam, R.; Subramanian, R. S.

1996-01-01

The migration of an isolated gas bubble in an immiscible liquid possessing a temperature gradient is analyzed in the absence of gravity. The driving force for the bubble motion is the shear stress at the interface which is a consequence of the temperature dependence of the surface tension. The analysis is performed under conditions for which the Marangoni number is large, i.e. energy is transferred predominantly by convection. Velocity fields in the limit of both small and large Reynolds numbers are used. The thermal problem is treated by standard boundary layer theory. The outer temperature field is obtained in the vicinity of the bubble. A similarity solution is obtained for the inner temperature field. For both small and large Reynolds numbers, the asymptotic values of the scaled migration velocity of the bubble in the limit of large Marangoni numbers are calculated. The results show that the migration velocity has the same scaling for both low and large Reynolds numbers, but with a different coefficient. Higher order thermal boundary layers are analyzed for the large Reynolds number flow field and the higher order corrections to the migration velocity are obtained. Results are also presented for the momentum boundary layer and the thermal wake behind the bubble, for large Reynolds number conditions.

Deterministic Migration-Based Separation of White Blood Cells.

PubMed

Kim, Byeongyeon; Choi, Young Joon; Seo, Hyekyung; Shin, Eui-Cheol; Choi, Sungyoung

2016-10-01

Functional and phenotypic analyses of peripheral white blood cells provide useful clinical information. However, separation of white blood cells from peripheral blood requires a time-consuming, inconvenient process and thus analyses of separated white blood cells are limited in clinical settings. To overcome this limitation, a microfluidic separation platform is developed to enable deterministic migration of white blood cells, directing the cells into designated positions according to a ridge pattern. The platform uses slant ridge structures on the channel top to induce the deterministic migration, which allows efficient and high-throughput separation of white blood cells from unprocessed whole blood. The extent of the deterministic migration under various rheological conditions is explored, enabling highly efficient migration of white blood cells in whole blood and achieving high-throughput separation of the cells (processing 1 mL of whole blood less than 7 min). In the separated cell population, the composition of lymphocyte subpopulations is well preserved, and T cells secrete cytokines without any functional impairment. On the basis of the results, this microfluidic platform is a promising tool for the rapid enrichment of white blood cells, and it is useful for functional and phenotypic analyses of peripheral white blood cells. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multiple testing of food contact materials: a predictive algorithm for assessing the global migration from silicone moulds.

PubMed

Elskens, Marc; Vloeberghs, Daniel; Van Elsen, Liesbeth; Baeyens, Willy; Goeyens, Leo

2012-09-15

For reasons of food safety, packaging and food contact materials must be submitted to migration tests. Testing of silicone moulds is often very laborious, since three replicate tests are required to decide about their compliancy. This paper presents a general modelling framework to predict the sample's compliance or non-compliance using results of the first two migration tests. It compares the outcomes of models with multiple continuous predictors with a class of models involving latent and dummy variables. The model's prediction ability was tested using cross and external validations, i.e. model revalidation each time a new measurement set became available. At the overall migration limit of 10 mg dm(-2), the relative uncertainty on a prediction was estimated to be ~10%. Taking the default values for α and β equal to 0.05, the maximum value that can be predicted for sample compliance was therefore 7 mg dm(-2). Beyond this limit the risk for false compliant results increases significantly, and a third migration test should be performed. The result of this latter test defines the sample's compliance or non-compliance. Propositions for compliancy control inspired by the current dioxin control strategy are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Faunal record identifies Bering isthmus conditions as constraint to end-Pleistocene migration to the New World.

PubMed

Meiri, Meirav; Lister, Adrian M; Collins, Matthew J; Tuross, Noreen; Goebel, Ted; Blockley, Simon; Zazula, Grant D; van Doorn, Nienke; Dale Guthrie, R; Boeskorov, Gennady G; Baryshnikov, Gennady F; Sher, Andrei; Barnes, Ian

2014-02-07

Human colonization of the New World is generally believed to have entailed migrations from Siberia across the Bering isthmus. However, the limited archaeological record of these migrations means that details of the timing, cause and rate remain cryptic. Here, we have used a combination of ancient DNA, 14C dating, hydrogen and oxygen isotopes, and collagen sequencing to explore the colonization history of one of the few other large mammals to have successfully migrated into the Americas at this time: the North American elk (Cervus elaphus canadensis), also known as wapiti. We identify a long-term occupation of northeast Siberia, far beyond the species's current Old World distribution. Migration into North America occurred at the end of the last glaciation, while the northeast Siberian source population became extinct only within the last 500 years. This finding is congruent with a similar proposed delay in human colonization, inferred from modern human mitochondrial DNA, and suggestions that the Bering isthmus was not traversable during parts of the Late Pleistocene. Our data imply a fundamental constraint in crossing Beringia, placing limits on the age and mode of human settlement in the Americas, and further establish the utility of ancient DNA in palaeontological investigations of species histories.

Population perspectives on the causes of international migration.

PubMed

Stahl, C

1987-06-01

The paper considers the causes of international voluntary labor migration from the economic perspective of supply of and demand for labor force. Changing global economic forces figure in the relevant decisions of individuals, industries, and countries. The author 1st examines global economic forces responsible for creating an unlimited supply of migrant labor within the 3rd world ready to work abroad. Reasons why a marked proportion of international labor migration is sourced in a limited number of countries are then discussed, followed by consideration of selectivity factors for laborers coming from certain subpopulations within given countries. Economic forces supporting demand for labor in countries of immigration are then discussed, with attention to the limits of growth in demand. The author concludes that immigration policies of comparatively wealthy countries determine the magnitude of international labor migration. These policies, however, are developed on the basis of perceived labor needs of the country, and are subject to become more restrictive as foreign workers increasingly impose upon the cultural space of the indigenous population. Restricting further immigration to workers only, not their dependents, is not encouraged as viable policy. Further discussion is included on increasing international economic inequalities resulting from international labor migration, and the role of source countries in ensuring the provision of suitable working conditions for immigrant workers.

Radar Interferometry Detection of Hinge Line Migration on Rutford Ice Stream and Carlson Inlet, Antarctica

NASA Technical Reports Server (NTRS)

Rignot, Eric

1997-01-01

Satellite synthetic-aperture radar (SAR) Interferometry is employed to map the hinge line, or limit of tidal flexing, of Rutford Ice Stream and Carlson Inlet, Antarctica, and detect its migration between 1992 and 1996. The hinge line is mapped using a model fit from an elastic beam theory.

Flight response of slope-soaring birds to seasonal variation in thermal generation

Treesearch

Adam E. Duerr; Tricia A. Miller; Michael Lanzone; David Brandes; Jeff Cooper; Kieran O' Malley; Charles Maisonneuve; Junior A. Tremblay; Todd Katzner

2014-01-01

Animals respond to a variety of environmental cues, including weather conditions, when migrating. Understanding the relationship between weather and migration behaviour is vital to assessing time- and energy limitations of soaring birds. Different soaring modes have different efficiencies, are dependent upon different types of subsidized lift and are weather dependent...

Population genetic analysis infers mMigration pathways of Phytophthora ramorum in US nurseries

Treesearch

Erica M. Goss; Meg Larsen; Gary A. Chastagner; Donald R. Givens; Niklaus J. Grünwald; Barbara Jane Howlett

2009-01-01

Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in...

Remote Data Retrieval for Bioinformatics Applications: An Agent Migration Approach

PubMed Central

Gao, Lei; Dai, Hua; Zhang, Tong-Liang; Chou, Kuo-Chen

2011-01-01

Some of the approaches have been developed to retrieve data automatically from one or multiple remote biological data sources. However, most of them require researchers to remain online and wait for returned results. The latter not only requires highly available network connection, but also may cause the network overload. Moreover, so far none of the existing approaches has been designed to address the following problems when retrieving the remote data in a mobile network environment: (1) the resources of mobile devices are limited; (2) network connection is relatively of low quality; and (3) mobile users are not always online. To address the aforementioned problems, we integrate an agent migration approach with a multi-agent system to overcome the high latency or limited bandwidth problem by moving their computations to the required resources or services. More importantly, the approach is fit for the mobile computing environments. Presented in this paper are also the system architecture, the migration strategy, as well as the security authentication of agent migration. As a demonstration, the remote data retrieval from GenBank was used to illustrate the feasibility of the proposed approach. PMID:21701677

Migration studies of 3-chloro-1,2-propanediol (3-MCPD) in polyethylene extrusion-coated paperboard food packaging.

PubMed

Pace, Gregory V; Hartman, Thomas G

2010-06-01

The manufacturing process of paperboard food packaging can produce small quantities of 3-chloro-1,2-propanediol (3-MCPD or 3-monochloropropane-1,2-diol) when wet-strength resins containing epichlorohydrin are used. 3-MCPD is from the same family as 1,3-dichloro-2-propanol (1,3-DCP), which is known to cause cancer in animals. 3-MCPD has been found in acid hydrolyzed vegetable protein, Asian sauces and paperboard for food contact. In this investigation, we conducted extraction studies to measure 3-MCPD migration into food simulant solvents from the food contact side of polyethylene extrusion-coated paperboard beverage cartons and aqueous extractions of cut pieces from the entire paperboard. We demonstrate that 3-MCPD confirmed present at concentrations up to 9.9 mg kg(-1) within the paperboard matrix does not migrate through the polyethylene-coated food contact surface. The aqueous extraction of the entire paperboard and food contact side extractions with aqueous/acidic food simulants were performed using US Food and Drug Administration (FDA) and European Commission (EU) migration testing protocols. We also show that no significant amount of 3-MCPD migrates through the unskived edges on the inside seam of the paperboard structure. The methodology for the aqueous and migration cell extractions using GC-MS analyses was validated with a limit of quantification (LOQ) of 0.009 mg kg(-1) and a limit of detection (LOD) of 0.005 mg kg(-1).

Multi-frequency subspace migration for imaging of perfectly conducting, arc-like cracks in full- and limited-view inverse scattering problems

NASA Astrophysics Data System (ADS)

Park, Won-Kwang

2015-02-01

Multi-frequency subspace migration imaging techniques are usually adopted for the non-iterative imaging of unknown electromagnetic targets, such as cracks in concrete walls or bridges and anti-personnel mines in the ground, in the inverse scattering problems. It is confirmed that this technique is very fast, effective, robust, and can not only be applied to full- but also to limited-view inverse problems if a suitable number of incidents and corresponding scattered fields are applied and collected. However, in many works, the application of such techniques is heuristic. With the motivation of such heuristic application, this study analyzes the structure of the imaging functional employed in the subspace migration imaging technique in two-dimensional full- and limited-view inverse scattering problems when the unknown targets are arbitrary-shaped, arc-like perfectly conducting cracks located in the two-dimensional homogeneous space. In contrast to the statistical approach based on statistical hypothesis testing, our approach is based on the fact that the subspace migration imaging functional can be expressed by a linear combination of the Bessel functions of integer order of the first kind. This is based on the structure of the Multi-Static Response (MSR) matrix collected in the far-field at nonzero frequency in either Transverse Magnetic (TM) mode (Dirichlet boundary condition) or Transverse Electric (TE) mode (Neumann boundary condition). The investigation of the expression of imaging functionals gives us certain properties of subspace migration and explains why multi-frequency enhances imaging resolution. In particular, we carefully analyze the subspace migration and confirm some properties of imaging when a small number of incident fields are applied. Consequently, we introduce a weighted multi-frequency imaging functional and confirm that it is an improved version of subspace migration in TM mode. Various results of numerical simulations performed on the far-field data affected by large amounts of random noise are similar to the analytical results derived in this study, and they provide a direction for future studies.

A case study of methane gas migration through sealed mine GOB into active mine workings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, F.; McCall, F.E.; Trevits, M.A.

1995-12-31

The U.S. Bureau of Mines investigated the influence of atmospheric pressure changes on methane gas migration through mine seals at a mine site located in the Pittsburgh Coalbed. The mine gained access to a coal reserve through part of an abandoned mine and constructed nine seals to isolate the extensive old workings from the active mine area. Underground problems were experienced when atmospheric pressure fell, causing methane gas to migrate around the seals and into the active workings. During mining operations, methane gas levels exceeded legal limits and coal production was halted until the ventilation system could be improved. Whenmore » mining resumed with increased air flow, methane gas concentrations occasionally exceeded the legal limits and production had to be halted until the methane level fell within the mandated limit. To assist the ventilation system, a pressure relief borehole located in the abandoned workings near the mine seals was proposed. Preliminary estimates by a gob gas simulator (computer model) suggested that a 0.76 m (2.5 ft) diameter pressure relief borehole with an exhaust fan would be necessary to remove enough methane from the abandoned area so that the ventilation system could dilute the gas in the active workings. However, by monitoring methane gas emissions and seal pressure, during periods of low atmospheric pressure, the amount of methane gas that migrated into the active mine workings was calculated. Researchers then determined that a relief borehole, 20.3 cm (8-in) with an exhaust fan could remove at least twice the maximum measured volume of migrating methane gas. Because gas concentrations in the abandoned workings could potentially reach explosive limits, it was proposed that the mine eliminate the exhaust fan. Installation of the recommended borehole and enlarging two other ventilation boreholes located In the abandoned area reduced methane gas leakage through the seals by at least 63%.« less

Increasing the realism of projected tree species ranges by incorporating migration potential: an eastern US case study

NASA Astrophysics Data System (ADS)

Rogers, B. M.; Jantz, P.; Goetz, S. J.

2015-12-01

Models of vegetation distributions are used for a wide variety of purposes, from global assessments of biome shifts and biogeochemical feedbacks to local management planning. Dynamic vegetation models, mostly mechanistic in origin, are valuable for regional to global studies but remain limited for more local-scale applications, especially those that require species-specific responses to climate change. Species distribution models (SDMs) are broadly used for such applications, but these too have several outstanding limitations, one of the most prominent being a lack of dispersal and migration. Several hybrid models have recently been developed, but these generally require detailed parameterization of species-level attributes that may not be known. Here we present an approach to couple migration potential with SDM output for a large number of species in order to more realistically project future range shifts. We focus on 40 tree species in the eastern US of potential management concern, either because of their canopy dominance, ecosystem functions, or potential for utilizing future climates. Future climates were taken from a CMIP5 model ensemble average using RCP 4.5 and 8.5 scenarios. We used Random Forests to characterize current and future environmental suitability, and modeled migration as a negative exponential kernel that is affected by forest fragmentation and the density of current seed sources. We present results in a vulnerability framework relevant for a number of ongoing management activities in the region. We find an overarching pattern of northward and eastward range shifts, with high-elevation and northern species being the most adversely impacted. Because of limitations to migration, many newly suitable areas could not be utilized without active intervention. Only a few areas exhibited consistently favorable conditions that could be utilized by the relevant species, including the central Appalachian foothills and the Florida panhandle. We suggest that a continued effort to include migration potential into vegetation models can lead to more realistic results and management-relevant products.

Reverse time migration in tilted transversely isotropic media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Linbing; Rector III, James W.; Hoversten, G. Michael

2004-07-01

This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength inmore » the vertical direction and 1.5 wavelength in the lateral direction.« less

Identification and biochemical characterization of an acid sphingomyelinase-like protein from the bacterial plant pathogen Ralstonia solanacearum that hydrolyzes ATP to AMP but not sphingomyelin to ceramide.

PubMed

Airola, Michael V; Tumolo, Jessica M; Snider, Justin; Hannun, Yusuf A

2014-01-01

Acid sphingomyelinase (aSMase) is a human enzyme that catalyzes the hydrolysis of sphingomyelin to generate the bioactive lipid ceramide and phosphocholine. ASMase deficiency is the underlying cause of the genetic diseases Niemann-Pick Type A and B and has been implicated in the onset and progression of a number of other human diseases including cancer, depression, liver, and cardiovascular disease. ASMase is the founding member of the aSMase protein superfamily, which is a subset of the metallophosphatase (MPP) superfamily. To date, MPPs that share sequence homology with aSMase, termed aSMase-like proteins, have been annotated and presumed to function as aSMases. However, none of these aSMase-like proteins have been biochemically characterized to verify this. Here we identify RsASML, previously annotated as RSp1609: acid sphingomyelinase-like phosphodiesterase, as the first bacterial aSMase-like protein from the deadly plant pathogen Ralstonia solanacearum based on sequence homology with the catalytic and C-terminal domains of human aSMase. A biochemical characterization of RsASML does not support a role in sphingomyelin hydrolysis but rather finds RsASML capable of acting as an ATP diphosphohydrolase, catalyzing the hydrolysis of ATP and ADP to AMP. In addition, RsASML displays a neutral, not acidic, pH optimum and prefers Ni2+ or Mn2+, not Zn2+, for catalysis. This alters the expectation that all aSMase-like proteins function as acid SMases and expands the substrate possibilities of this protein superfamily to include nucleotides. Overall, we conclude that sequence homology with human aSMase is not sufficient to predict substrate specificity, pH optimum for catalysis, or metal dependence. This may have implications to the biochemically uncharacterized human aSMase paralogs, aSMase-like 3a (aSML3a) and aSML3b, which have been implicated in cancer and kidney disease, respectively, and assumed to function as aSMases.

Benthic habitat characterization and distribution from two representative sites of the deep-water SML Coral Province (Mediterranean)

NASA Astrophysics Data System (ADS)

Vertino, A.; Savini, A.; Rosso, A.; Di Geronimo, I.; Mastrototaro, F.; Sanfilippo, R.; Gay, G.; Etiope, G.

2010-03-01

Two sites (MS04 and MS06) from the Santa Maria di Leuca (SML) Coral Province were analyzed by a video and acoustic survey during the National Italian Project Apulian Plateau Bank Ecosystem Study (APLABES). Site MS04 (Atlantis Mound) is characterized by a sub-conical mound, 500 m wide and 25 m high, located at a water depth of about 650 m. Site MS06 (Yellow Chain) comprises several elongated reliefs (NNW-SSE-oriented), up to 25 m high and 500 m in maximum lateral extent, located at a depth of between 490 and 540 m. At both sites, two main mesohabitats (mound and intermound) containing several coral-bearing and -barren macrohabitats were observed in recorded videos and detected in side-scan sonographs. The coral-rich macrohabitats, characterized by densely packed colonies of the scleractinians Madrepora oculata and, secondarily, Lophelia pertusa ( M/ L), are typically restricted to the mound areas. The mud-dominated ones, almost devoid of M/L colonies, are more common within the intermound mesohabitat. However, on the most extensive mounds, both macrohabitat typologies exist. They are heterogeneously distributed on the mound surface, often showing a clear differentiation along two opposite flanks of the same topographic feature. M/ L-rich macrohabitats are preferentially located on top and along the mound northeastern flank, showing a typical step-like distribution, probably reflecting the arrangement of hard substrate outcrops. Along this flank, fan-shaped Madrepora colonies and sponges are often oriented NNW-SSE, implying, together with other evidence, a primary southwestern current flow. The hard-bottom macrohabitats of the southwestern mound flank are generally restricted to sparse exposed, subvertical to overhanging scarps as well as to heterometric boulders located at the scarp base. Their fauna is mainly characterized by small-sized organisms (such as sponges and solitary scleractinians) although m-sized boulders may locally host very large antipatharian colonies ( Leiopathes glaberrima). The heterogeneous distribution of the observed benthic macrohabitats seems to be strictly related to the local topography, the main current flow (and consequently larvae/food supply per unit of time), and the substrate typology (hard- vs. soft-bottom).

Fucose Migration in Intact Protonated Glycan Ions: A Universal Phenomenon in Mass Spectrometry.

PubMed

Mucha, Eike; Lettow, Maike; Marianski, Mateusz; Thomas, Daniel A; Struwe, Weston B; Harvey, David J; Meijer, Gerard; Seeberger, Peter H; von Helden, Gert; Pagel, Kevin

2018-06-18

Fucose is an essential deoxysugar that is found in a wide range of biologically relevant glycans and glycoconjugates. A recurring problem in mass spectrometric analyses of fucosylated glycans is the intramolecular migration of fucose units, which can lead to erroneous sequence assignments. This migration reaction is typically assigned to activation during collision-induced dissociation (CID) in tandem mass spectrometry (MS). In this work, we utilized cold-ion spectroscopy and show for the first time that fucose migration is not limited to fragments obtained in tandem MS and can also be observed in intact glycan ions. This observation suggests a possible low-energy barrier for this transfer reaction and generalizes fucose migration to an issue that may universally occur in any type of mass spectrometry experiment. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Seasonal movements and environmental triggers to fall migration of Sage Sparrows

USGS Publications Warehouse

Fesenmyer, K.A.; Knick, S.T.

2011-01-01

Post-breeding ecology of shrubland passerines prior to onset of migration is unknown relative to dynamics of breeding areas. We radiomarked and monitored 38 Sage Sparrows (Amphispiza belli ssp. nevadensis) at one site in Oregon and two in Nevada from September to mid-November 2007 to track local movements, estimate seasonal range sizes, and characterize weather patterns triggering onset of migration. Median area used by Sage Sparrows monitored between 3 and 18 days during or prior to migration was 14 ha; maximum daily movement was 15 km. Radio-marked Sage Sparrows at each location departed individually, rather than en masse, corresponding with passage of cold front weather systems. Conventional telemetry techniques limited our ability to monitor Sage Sparrows beyond pre-migratory periods and precluded detecting and tracking actual movements during migration. ?? 2011 by the Wilson Ornithological Society.

An open access microfluidic device for the study of the physical limits of cancer cell deformation during migration in confined environments.

PubMed

Malboubi, Majid; Jayo, Asier; Parsons, Maddy; Charras, Guillaume

2015-08-16

During metastasis, cancerous cells leave the primary tumour, pass into the circulatory system, and invade into new tissues. To migrate through the wide variety of environments they encounter, the cells must be able to remodel their cell shape efficiently to squeeze through small gaps in the extracellular matrix or extravasate into the blood stream or lymphatic system. Several studies have shown that the nucleus is the main limiting factor to migration through small gaps (Wolf et al., 2013; Harada et al., 2014; Mak et al., 2013). To understand the physical limits of cancer cell translocation in confined environments, we have fabricated a microfluidic device to study their ability to adapt their nuclear and cellular shape when passing through small gaps. The device is open access for ease of use and enables examination of the effect of different levels of spatial confinement on cell behaviour and morphology simultaneously. The results show that increasing cell confinement decreases the ability of cells to translocate into small gaps and that cells cannot penetrate into the microchannels below a threshold cross-section.

Migration and depressive symptoms in migrant-sending areas: findings from the survey of internal migration and health in China.

PubMed

Lu, Yao; Hu, Peifeng; Treiman, Donald J

2012-08-01

China has experienced large-scale internal migration and growing mental health disorders. Limited research has examined the relationship between the two processes. We examined the association between labor out-migration and depressive symptoms of family members left behind in migrant-sending areas. We conducted a multistage probability sample survey of Chinese adults in 2008 ("Internal Migration and Health in China"), including 787 people in rural migrant-sending areas. To study whether adults in out-migrant households were more likely to experience depressive symptoms (CES-D) than were adults in non-migrant households, we used multivariate regressions and adjusted for a wide range of confounding factors and for the complex sampling design. Adults in households with labor out-migrants were more likely to report depressive symptoms than those in households without out-migrants, presumably a result of the absence of family members. However, monetary remittances from labor migrants buffered the mental health costs of out-migration. Labor out-migration has important consequences for the mental health in migrant-sending communities. There is an urgent need to address the psychological costs of migration and to promote regular remittances.

Landbird migration in the American West: Recent progress and future research directions

USGS Publications Warehouse

Carlisle, J.D.; Skagen, S.K.; Kus, B.E.; van Riper, Charles; Paxton, K.L.; Kelly, J.F.

2009-01-01

Our knowledge of avian behaviors during the nonbreeding period still lags behind that of the breeding season, but the last decade has witnessed a proliferation in research that has yielded significant progress in understanding migration patterns of North American birds. And, although historically the great majority of migration research has been conducted in the eastern half of the continent, there has been much recent progress on aspects of avian migration in the West. In particular, expanded use of techniques such as radar, plasma metabolites, mist-netting, count surveys, stable isotopes, genetic data, and animal tracking, coupled with an increase in multi-investigator collaborations, have all contributed to this growth of knowledge. There is increasing recognition that migration is likely the most limiting time of year for migratory birds, increasing the importance of continuing to decipher patterns of stopover ecology, identifying critical stopover habitats, and documenting migration routes in the diverse and changing landscapes of the American West. Here, we review and briefly synthesize the latest findings and advances in avian migration and consider research needs to guide future research on migration in the West. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

Development of Matched (migratory Analytical Time Change Easy Detection) Method for Satellite-Tracked Migratory Birds

NASA Astrophysics Data System (ADS)

Doko, Tomoko; Chen, Wenbo; Higuchi, Hiroyoshi

2016-06-01

Satellite tracking technology has been used to reveal the migration patterns and flyways of migratory birds. In general, bird migration can be classified according to migration status. These statuses include the wintering period, spring migration, breeding period, and autumn migration. To determine the migration status, periods of these statuses should be individually determined, but there is no objective method to define 'a threshold date' for when an individual bird changes its status. The research objective is to develop an effective and objective method to determine threshold dates of migration status based on satellite-tracked data. The developed method was named the "MATCHED (Migratory Analytical Time Change Easy Detection) method". In order to demonstrate the method, data acquired from satellite-tracked Tundra Swans were used. MATCHED method is composed by six steps: 1) dataset preparation, 2) time frame creation, 3) automatic identification, 4) visualization of change points, 5) interpretation, and 6) manual correction. Accuracy was tested. In general, MATCHED method was proved powerful to identify the change points between migration status as well as stopovers. Nevertheless, identifying "exact" threshold dates is still challenging. Limitation and application of this method was discussed.

Improvement of Human Keratinocyte Migration by a Redox Active Bioelectric Dressing

PubMed Central

Banerjee, Jaideep; Das Ghatak, Piya; Roy, Sashwati; Khanna, Savita; Sequin, Emily K.; Bellman, Karen; Dickinson, Bryan C.; Suri, Prerna; Subramaniam, Vish V.; Chang, Christopher J.; Sen, Chandan K.

2014-01-01

Exogenous application of an electric field can direct cell migration and improve wound healing; however clinical application of the therapy remains elusive due to lack of a suitable device and hence, limitations in understanding the molecular mechanisms. Here we report on a novel FDA approved redox-active Ag/Zn bioelectric dressing (BED) which generates electric fields. To develop a mechanistic understanding of how the BED may potentially influence wound re-epithelialization, we direct emphasis on understanding the influence of BED on human keratinocyte cell migration. Mapping of the electrical field generated by BED led to the observation that BED increases keratinocyte migration by three mechanisms: (i) generating hydrogen peroxide, known to be a potent driver of redox signaling, (ii) phosphorylation of redox-sensitive IGF1R directly implicated in cell migration, and (iii) reduction of protein thiols and increase in integrinαv expression, both of which are known to be drivers of cell migration. BED also increased keratinocyte mitochondrial membrane potential consistent with its ability to fuel an energy demanding migration process. Electric fields generated by a Ag/Zn BED can cross-talk with keratinocytes via redox-dependent processes improving keratinocyte migration, a critical event in wound re-epithelialization. PMID:24595050

Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

NASA Astrophysics Data System (ADS)

Chu, Kengyeh K.; Kusek, Mark E.; Liu, Linbo; Som, Avira; Yonker, Lael M.; Leung, Huimin; Cui, Dongyao; Ryu, Jinhyeob; Eaton, Alexander D.; Tearney, Guillermo J.; Hurley, Bryan P.

2017-04-01

A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro, but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to the trans-epithelial migration model, we can robustly monitor the spatial distribution as well as the quantity of neutrophils chemotactically crossing the epithelial boundary over time. Here, we demonstrate the imaging and quantitative migration results of our system as applied to neutrophils migrating across intestinal epithelia in response to a chemoattractant. We also demonstrate that perturbation of a key molecular event known to be critical for effective neutrophil trans-epithelial migration (CD18 engagement) substantially impacts this process both qualitatively and quantitatively.

Illuminating dynamic neutrophil trans-epithelial migration with micro-optical coherence tomography

PubMed Central

Chu, Kengyeh K.; Kusek, Mark E.; Liu, Linbo; Som, Avira; Yonker, Lael M.; Leung, Huimin; Cui, Dongyao; Ryu, Jinhyeob; Eaton, Alexander D.; Tearney, Guillermo J.; Hurley, Bryan P.

2017-01-01

A model of neutrophil migration across epithelia is desirable to interrogate the underlying mechanisms of neutrophilic breach of mucosal barriers. A co-culture system consisting of a polarized mucosal epithelium and human neutrophils can provide a versatile model of trans-epithelial migration in vitro, but observations are typically limited to quantification of migrated neutrophils by myeloperoxidase correlation, a destructive assay that precludes direct longitudinal study. Our laboratory has recently developed a new isotropic 1-μm resolution optical imaging technique termed micro-optical coherence tomography (μOCT) that enables 4D (x,y,z,t) visualization of neutrophils in the co-culture environment. By applying μOCT to the trans-epithelial migration model, we can robustly monitor the spatial distribution as well as the quantity of neutrophils chemotactically crossing the epithelial boundary over time. Here, we demonstrate the imaging and quantitative migration results of our system as applied to neutrophils migrating across intestinal epithelia in response to a chemoattractant. We also demonstrate that perturbation of a key molecular event known to be critical for effective neutrophil trans-epithelial migration (CD18 engagement) substantially impacts this process both qualitatively and quantitatively. PMID:28368012

Understanding the Impact of Migration on HIV Risk: An Analysis of Mexican Migrants' Sexual Practices, Partners, and Contexts by Migration Phase.

PubMed

Zhang, Xiao; Rhoads, Natalie; Rangel, Maria Gudelia; Hovell, Melbourne F; Magis-Rodriguez, Carlos; Sipan, Carol L; Gonzalez-Fagoaga, J Eduardo; Martínez-Donate, Ana P

2017-03-01

HIV risk among Mexican migrants varies across migration phases (pre-departure, transit, destination, interception, and return), but there is limited knowledge about specific sexual behaviors, characteristics of sexual partners, and sexual contexts at different migration stages. To fill the gap, we used data from a cross-sectional population-based survey conducted in Tijuana, Mexico. Information on migration phase and last sexual encounter was collected from 1219 male migrants. Our findings suggest that compared to pre-departure migrants, repeat migrants returning from communities of origin were more likely to have sex with male partners, use substances before sex, and not use condoms; migrants in the transit phase in the Mexican border were more likely to have sex with casual partners and sex workers; and migrants in the interception phase were more likely to engage in anal sex and use substances before sex. Sexual behaviors, partners, and contexts vary significantly among migrants at different migration phases. Tailored HIV prevention programs targeting Mexican migrants need to be developed and implemented at all migration phases.

Understanding the Impact of Migration on HIV Risk: An Analysis of Mexican Migrants’ Sexual Practices, Partners, and Contexts by Migration Phase

PubMed Central

Zhang, Xiao; Rhoads, Natalie; Rangel, Maria Gudelia; Hovell, Melbourne F.; Magis-Rodriguez, Carlos; Sipan, Carol L.; Gonzalez-Fagoaga, J. Eduardo; Martínez-Donate, Ana P.

2018-01-01

HIV risk among Mexican migrants varies across migration phases (pre-departure, transit, destination, interception, and return), but there is limited knowledge about specific sexual behaviors, characteristics of sexual partners, and sexual contexts at different migration stages. To fill the gap, we used data from a cross-sectional population-based survey conducted in Tijuana, Mexico. Information on migration phase and last sexual encounter was collected from 1,219 male migrants. Our findings suggested that compared to pre-departure migrants, repeat migrants returning from communities of origin were more likely to have sex with male partners, use substances before sex, and not use condoms; migrants with a recent stay in the Mexican border were more likely to have sex with casual partners and sex workers; and migrants in the interception phase were more likely to engage in anal sex and use substances before sex. Sexual behaviors, partners, and contexts vary significantly among migrants at different migration phases. Tailored HIV prevention programs targeting Mexican migrants need to be developed and implemented at all migration phases. PMID:27888370

Innate control of actin nucleation determines two distinct migration behaviours in dendritic cells

PubMed Central

Vargas, Pablo; Maiuri, Paolo; Bretou, Marine; Sáez, Pablo J.; Pierobon, Paolo; Maurin, Mathieu; Chabaud, Mélanie; Lankar, Danielle; Obino, Dorian; Terriac, Emmanuel; Raab, Matthew; Thiam, Hawa-Racine; Brocker, Thomas; Kitchen-Goosen, Susan M.; Alberts, Arthur S.; Sunareni, Praveen; Xia, Sheng; Li, Rong; Voituriez, Raphael; Piel, Matthieu; Lennon-Duménil, Ana-Maria

2018-01-01

Dendritic cell (DC) migration in peripheral tissues serves two main functions: antigen sampling by immature DCs, and chemokine-guided migration towards lymphatic vessels (LVs) on maturation. These migratory events determine the efficiency of the adaptive immune response. Their regulation by the core cell locomotion machinery has not been determined. Here, we show that the migration of immature DCs depends on two main actin pools: a RhoA–mDia1-dependent actin pool located at their rear, which facilitates forward locomotion; and a Cdc42–Arp2/3-dependent actin pool present at their front, which limits migration but promotes antigen capture. Following TLR4–MyD88-induced maturation, Arp2/3-dependent actin enrichment at the cell front is markedly reduced. Consequently, mature DCs switch to a faster and more persistent mDia1-dependent locomotion mode that facilitates chemotactic migration to LVs and lymph nodes. Thus, the differential use of actin-nucleating machineries optimizes the migration of immature and mature DCs according to their specific function. PMID:26641718

Thermal migration of alloying agents in aluminium

NASA Astrophysics Data System (ADS)

Cooil, S. P.; Mørtsell, E. A.; Mazzola, F.; Jorge, M.; Wenner, S.; Edmonds, M. T.; Thomsen, L.; Klemm, H. W.; Peschel, G.; Fuhrich, A.; Prieto, M.; Schmidt, Th; Miwa, J. A.; Holmestad, R.; Wells, J. W.

2016-11-01

The in situ thermal migration of alloying agents in an Al-Mg-Si-Li alloy is studied using surface sensitive photo-electron and electron diffraction/imaging techniques. Starting with the preparation of an almost oxide free surface (oxide thickness = 0.1 nm), the relative abundance of alloying agents (Mg, Li and Si) at the surface are recorded at various stages of thermal annealing, from room temperature to melting (which is observed at 550 ◦C). Prior to annealing, the surface abundances are below the detection limit ≪1%, in agreement with their bulk concentrations of 0.423% Si, 0.322% Mg and 0.101% Li (atomic %). At elevated temperatures, all three alloying agents appear at drastically increased concentrations (13.3% Si, 19.7% Mg and 45.3% Li), but decrease again with further elevation of the annealing temperature or after melting. The temperature at which the migration occurs is species dependent, with Li migration occurring at significantly higher temperatures than Si and Mg. The mechanism of migration also appears to be species dependent with Li migration occurring all over the surface but Mg migration being restricted to grain boundaries.

Towards the establishment of landbird migration monitoring networks in the United States

Treesearch

Jay D. Carlisle; C. John Ralph

2005-01-01

Migration monitoring of landbirds, in its various forms, is a well-established research endeavor across much of North America. While monitoring efforts at individual sites have contributed much to our knowledge of the biology of migrants, these studies have limited potential for population monitoring and for addressing certain broader questions about migrants....

What Does Global Migration Network Say about Recent Changes in the World System Structure?

ERIC Educational Resources Information Center

Zinkina, Julia; Korotayev, Andrey

2014-01-01

Purpose: The aim of this paper is to investigate whether the structure of the international migration system has remained stable through the recent turbulent changes in the world system. Design/methodology/approach: The methodology draws on the social network analysis framework--but with some noteworthy limitations stipulated by the specifics of…

Migration of nanosized layered double hydroxide platelets from polylactide nanocomposite films.

PubMed

Schmidt, B; Katiyar, V; Plackett, D; Larsen, E H; Gerds, N; Koch, C Bender; Petersen, J H

2011-01-01

Melt-extruded L-polylactide (PLA) nanocomposite films were prepared from commercially available PLA and laurate-modified Mg-Al layered double hydroxide (LDH-C12). Three films were tested for total migration as well as specific migration of LDH, tin, laurate and low molecular weight PLA oligomers (OLLA). This is the first reported investigation on the migration properties of PLA-LDH nanocomposite films. The tests were carried out as part of an overall assessment of the suitability of such films for use as food contact materials (FCM). Total migration was determined according to a European standard method. All three films showed migration of nanosized LDH, which was quantified using acid digestion followed by inductively coupled plasma mass spectrometric (ICP-MS) detection of (26)Mg. Migration of LDH from the films was also confirmed by examining migrates using transmission electron microscopy (TEM) and was attributed indirectly to the significant PLA molecular weight reduction observed in extruded PLA-LDH-C12 films. Migration of tin was detected in two of the film samples prepared by dispersion of LDH-C12 using a masterbatch technique and migration of the laurate organomodifier took place from all three film types. The results indicate that the material properties are in compliance with the migration limits for total migration and specific lauric acid migration as set down by the EU legislation for FCM, at least if a reduction factor for fresh meat is taken into consideration. The tin detected arises from the use of organotin catalysts in the manufacture of PLA.

A versatile microfluidic platform for the study of cellular interactions between endothelial cells and neutrophils.

PubMed

Wu, Xiaojie; Newbold, Molly A; Gao, Zhe; Haynes, Christy L

2017-05-01

Endothelial migration is a critical physiological process during vascular angiogenesis, growth and development, as well as in various disease conditions, such as cancer and cardiovascular diseases. Neutrophil migration, known as the important characteristic of immune responses, is also recognized as a contributor to the diseases involving endothelial migration. Herein, the mutually dependent relationship between neutrophil recruitment and endothelial migration was studied on a microfluidic platform for the first time. An in vivo-like microenvironment is created inside microfluidic devices by embedding a gel scaffold into the micro-chambers. This approach, with controllable stable chemical gradients and the ability to quantitate interaction characteristics, overcomes the limitations of the current in vivo and in vitro assays for cell migration studies. The number of neutrophils migrating through the endothelial cell layer is heavily influenced by the concentration of vascular endothelial growth factor (VEGF) that induces endothelial cell migration in the gel scaffold, and is not as correlated to the concentration of chemokine solution used for initiating neutrophil migration. More importantly, neutrophil migration diminishes the effects of the drug that inhibits endothelial migration and this process is regulated by the concentration of chemokine molecules instead of VEGF concentration. The results presented herein demonstrate the complicated cellular interactions between endothelial cells and neutrophils: endothelial migration delicately regulates neutrophil migration while the presence of neutrophils stabilizes the structures of endothelial migration. This study provides deeper understanding of the dynamic cellular interactions between neutrophils and endothelial cells as well as the pathogenesis of relevant diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Formaldehyde migration in aqueous extracts from paper and cardboard food packaging materials in Turkey.

PubMed

Dogan, Canan Ekinci; Sancı, Rukiye

2015-01-01

Migration of formaldehyde to aqueous extracts from paper and cardboard food packaging materials was determined by an ultraviolet visible-spectrophotometric method at 410 nm. Intraday and interday precision of the method, expressed as coefficient of variation, varied between 1.5 to 4.4% and 7 to 8.8%, respectively. The limit of quantification was 0.28 mg kg(-1) for formaldehyde in aqueous extracts. The recovery of the method was over 90% for two different concentration levels in aqueous extracts. The method was applied to the migration of formaldehyde to aqueous extracts from 31 different paper and cardboard materials collected from the packaging sector, intended for food contact, such as tea filters, hot water filters, paper pouches and folding boxes. The results were between limit of detection 0.23 mg/kg and 40 mg kg(-1) and were evaluated according to the relevant directives.

Technical Advance: New in vitro method for assaying the migration of primary B cells using an endothelial monolayer as substrate.

PubMed

Stewart-Hutchinson, Phillip J; Szasz, Taylor P; Jaeger, Emily R; Onken, Michael D; Cooper, John A; Morley, Sharon Celeste

2017-09-01

Migration of B cells supports their development and recruitment into functional niches. Therefore, defining factors that control B cell migration will lead to a better understanding of adaptive immunity. In vitro cell migration assays with B cells have been limited by poor adhesion of cells to glass coated with adhesion molecules. We have developed a technique using monolayers of endothelial cells as the substrate for B cell migration and used this technique to establish a robust in vitro assay for B cell migration. We use TNF-α to up-regulate surface expression of the adhesion molecule VCAM-1 on endothelial cells. The ligand VLA-4 is expressed on B cells, allowing them to interact with the endothelial monolayer and migrate on its surface. We tested our new method by examining the role of L-plastin (LPL), an F-actin-bundling protein, in B cell migration. LPL-deficient (LPL -/- ) B cells displayed decreased speed and increased arrest coefficient compared with wild-type (WT) B cells, following chemokine stimulation. However, the confinement ratios for WT and LPL -/- B cells were similar. Thus, we demonstrate how the use of endothelial monolayers as a substrate will support future interrogation of molecular pathways essential to B cell migration. © Society for Leukocyte Biology.

A novel honeycomb cell assay kit designed for evaluating horizontal cell migration in response to functionalized self-assembling peptide hydrogels

NASA Astrophysics Data System (ADS)

Guan, Fengyi; Lu, Jiaju; Wang, Xiumei

2017-03-01

A clear understanding on cell migration behaviors contributes to designing novel biomaterials in tissue engineering and elucidating related tissue regeneration processes. Many traditional evaluation methods on cell migration including scratch assay and transwell migration assay possess all kinds of limitations. In this study, a novel honeycomb cell assay kit was designed and made of photosensitive resin by 3D printing. This kit has seven hexagonal culture chambers so that it can evaluate the horizontal cell migration behavior in response to six surrounding environments simultaneously, eliminating the effect of gravity on cells. Here this cell assay kit was successfully applied to evaluate endothelial cell migration cultured on self-assembling peptide (SAP) RADA (AcN-RADARADARADARADA-CONH2) nanofiber hydrogel toward different functionalized SAP hydrogels. Our results indicated that the functionalized RADA hydrogels with different concentration of bioactive motifs of KLT or PRG could induce cell migration in a dose-dependent manner. The total number and migration distance of endothelial cells on functionalized SAP hydrogels significantly increased with increasing concentration of bioactive motif PRG or KLT. Therefore, the honeycomb cell assay kit provides a simple, efficient and convenient tool to investigate cell migration behavior in response to multi-environments simultaneously.

Migration behaviour of silicone moulds in contact with different foodstuffs.

PubMed

Helling, Ruediger; Kutschbach, Katja; Joachim Simat, Thomas

2010-03-01

Various foodstuffs were prepared in silicone baking moulds and analyzed for siloxane migration using a previously developed and validated (1)H-NMR method. Meat loaf significantly exceeded the overall migration limit of 60 mg kg(-1) (10 mg sdm(-1)) in the first and third experiment. The highest siloxane migration found in a meat loaf after preparation in a commercial mould was 177 mg kg(-1). In contrast, milk-based food showed very low or non-detectable migration (<2.4 mg kg(-1)), even containing high fat levels. Similar results were achieved using 50% ethanol as the simulant for milk-based products, as defined in the Plastics Directive 2007/19/EEC. After solvent extraction of the moulds in simulating long-term usage, no further migration into the food was detectable, indicating that there is no significant formation of low molecular weight, potentially migrating siloxanes from the elastomer. During repeated usage, the moulds showed a high uptake of fat: up to 8.0 g fat per kg elastomer. Proper tempering of the moulds had a major influence on the migration properties of siloxanes into different foodstuffs. Non-tempered moulds with a high level of volatile organic compounds (1.1%) were shown to have considerably higher migration than the equivalent tempered moulds.

[Maintenance treatment in opioid-dependent patients with migration background].

PubMed

Bald, L K; Schouler-Ocak, M; Penka, S; Schoofs, N; Häbel, T; Bermpohl, F; Gutwinski, S

2016-05-01

No regional analyses regarding opioid-dependent patients in maintenance treatment with a migration background have so far been performed in German-speaking countries. This study examined patients with and without a migration background regarding socioeconomic parameters, characteristics of dependency and attitude towards opiate maintenance treatment (OMT). From May to October 2011 patients in OMT from all of the 20 psychiatry clinics and 110 physician practices in Berlin with a licence to provide OMT were included in this analysis. Out of the 986 participating patients, 956 gave information on migration background and of these, 204 (21.3 %) originated from a country other than Germany. Compared to patients without a migration background, their participation in a maintenance program was significantly shorter and they more often expressed a desire to end OMT and wanted a limited duration of OMT. The differences regarding duration of OMT and the wish to end OMT can reflect a stronger desire for abstinence and a different attitude towards maintenance treatment of patients with a migration background.

Transparent process migration: Design alternatives and the Sprite implementation

NASA Technical Reports Server (NTRS)

Douglis, Fred; Ousterhout, John

1991-01-01

The Sprite operating system allows executing processes to be moved between hosts at any time. We use this process migration mechanism to offload work onto idle machines, and also to evict migrated processes when idle workstations are reclaimed by their owners. Sprite's migration mechanism provides a high degree of transparency both for migrated processes and for users. Idle machines are identified, and eviction is invoked, automatically by daemon processes. On Sprite it takes up to a few hundred milliseconds on SPARCstation 1 workstations to perform a remote exec, while evictions typically occur in a few seconds. The pmake program uses remote invocation to invoke tasks concurrently. Compilations commonly obtain speedup factors in the range of three to six; they are limited primarily by contention for centralized resources such as file servers. CPU-bound tasks such as simulations can make more effective use of idle hosts, obtaining as much as eight-fold speedup over a period of hours. Process migration has been in regular service for over two years.

Seasonal migration of marsupial megafauna in Pleistocene Sahul (Australia-New Guinea).

PubMed

Price, Gilbert J; Ferguson, Kyle J; Webb, Gregory E; Feng, Yue-Xing; Higgins, Pennilyn; Nguyen, Ai Duc; Zhao, Jian-Xin; Joannes-Boyau, Renaud; Louys, Julien

2017-09-27

Seasonal two-way migration is an ecological phenomenon observed in a wide range of large-bodied placental mammals, but is conspicuously absent in all modern marsupials. Most extant marsupials are typically smaller in body size in comparison to their migratory placental cousins, possibly limiting their potential to undertake long-distance seasonal migrations. But what about earlier, now-extinct giant marsupial megafauna? Here we present new geochemical analyses which show that the largest of the extinct marsupial herbivores, the enormous wombat-like Diprotodon optatum , undertook seasonal, two-way latitudinal migration in eastern Sahul (Pleistocene Australia-New Guinea). Our data infer that this giant marsupial had the potential to perform round-trip journeys of as much as 200 km annually, which is reminiscent of modern East African mammal migrations. These findings provide, to our knowledge, the first evidence for repetitive seasonal migration in any metatherian (including marsupials), living or extinct, and point to an ecological phenomenon absent from the continent since the Late Pleistocene. © 2017 The Author(s).

Corresponding long-term shifts in stream temperature and invasive fish migration

USGS Publications Warehouse

McCann, Erin L.; Johnson, Nicholas; Pangle, Kevin

2018-01-01

By investigating historic trapping records of invasive sea lamprey (Petromyzon marinus) throughout tributaries to the Laurentian Great Lakes, we found that upstream spawning migration timing was highly correlated with stream temperatures over large spatial and temporal scales. Furthermore, several streams in our study exceeded a critical spring thermal threshold (i.e., 15°C) and experienced peak spawning migration up to 30 days earlier since the 1980s, whereas others were relatively unchanged. Streams exhibiting warming trends and earlier migration were spatially clustered and generally found on the leeward side of the Great Lakes where the lakes most affect local climate. These findings highlight that all streams are not equally impacted by climate change and represent, to our knowledge, the first observation linking long-term changes in stream temperatures to shifts in migration timing of an invasive fish. Earlier sea lamprey migration in Great Lakes tributaries may improve young of the year growth and survival, but not limit their spatial distribution, making sea lamprey control more challenging.

Search for a more adequate test to predict the long-term migration from the PVC gaskets of metal lids into oily foods in glass jars.

PubMed

Graubardt, Nadine; Biedermann, Maurus; Fiselier, Katell; Bolzoni, Luciana; Pedrelli, Turno; Cavalieri, Chiara; Simoneau, Cathérine; Grob, Koni

2009-07-01

As shown previously, the conventional testing procedure for simulating long-term migration from the gaskets of metal closures into oily foods does not adequately reflect reality. It appears to be impossible to accelerate migration to the extent that the situation at the end of the shelf life of a product can be anticipated in a few days or weeks. Therefore, we investigated whether long-term migration could be extrapolated from migration rates determined for new lids. Jars were kept in the normal upright position. Since heat treatment may have a strong temporary impact, migration during the initial heating for pasteurization or sterilization and storage at ambient temperature were determined using different lids. Commercial products were recalled from sales points throughout Europe to determine the real migration over extended periods of time and for jars with differing histories. This migration was compared with data from the short-term testing to investigate whether an empirical relationship could be derived. The results show that the short-term test enables the comparison of lids and plasticizers in the initial phase of migration, but that long-term extrapolation presupposes more complex kinetic modeling. The results also demonstrate that the legal relevance of "official" testing methods should be reconsidered to avoid conflict when food contact materials comply with migration limits in the test but not in actual application.

Quantitative and qualitative approaches to identifying migration chronology in a continental migrant

USGS Publications Warehouse

Beatty, William S.; Kesler, Dylan C.; Webb, Elisabeth B.; Raedeke, Andrew H.; Naylor, Luke W.; Humburg, Dale D.

2013-01-01

The degree to which extrinsic factors influence migration chronology in North American waterfowl has not been quantified, particularly for dabbling ducks. Previous studies have examined waterfowl migration using various methods, however, quantitative approaches to define avian migration chronology over broad spatio-temporal scales are limited, and the implications for using different approaches have not been assessed. We used movement data from 19 female adult mallards (Anas platyrhynchos) equipped with solar-powered global positioning system satellite transmitters to evaluate two individual level approaches for quantifying migration chronology. The first approach defined migration based on individual movements among geopolitical boundaries (state, provincial, international), whereas the second method modeled net displacement as a function of time using nonlinear models. Differences in migration chronologies identified by each of the approaches were examined with analysis of variance. The geopolitical method identified mean autumn migration midpoints at 15 November 2010 and 13 November 2011, whereas the net displacement method identified midpoints at 15 November 2010 and 14 November 2011. The mean midpoints for spring migration were 3 April 2011 and 20 March 2012 using the geopolitical method and 31 March 2011 and 22 March 2012 using the net displacement method. The duration, initiation date, midpoint, and termination date for both autumn and spring migration did not differ between the two individual level approaches. Although we did not detect differences in migration parameters between the different approaches, the net displacement metric offers broad potential to address questions in movement ecology for migrating species. Ultimately, an objective definition of migration chronology will allow researchers to obtain a comprehensive understanding of the extrinsic factors that drive migration at the individual and population levels. As a result, targeted conservation plans can be developed to support planning for habitat management and evaluation of long-term climate effects.

Quantitative and qualitative approaches to identifying migration chronology in a continental migrant.

PubMed

Beatty, William S; Kesler, Dylan C; Webb, Elisabeth B; Raedeke, Andrew H; Naylor, Luke W; Humburg, Dale D

2013-01-01

The degree to which extrinsic factors influence migration chronology in North American waterfowl has not been quantified, particularly for dabbling ducks. Previous studies have examined waterfowl migration using various methods, however, quantitative approaches to define avian migration chronology over broad spatio-temporal scales are limited, and the implications for using different approaches have not been assessed. We used movement data from 19 female adult mallards (Anas platyrhynchos) equipped with solar-powered global positioning system satellite transmitters to evaluate two individual level approaches for quantifying migration chronology. The first approach defined migration based on individual movements among geopolitical boundaries (state, provincial, international), whereas the second method modeled net displacement as a function of time using nonlinear models. Differences in migration chronologies identified by each of the approaches were examined with analysis of variance. The geopolitical method identified mean autumn migration midpoints at 15 November 2010 and 13 November 2011, whereas the net displacement method identified midpoints at 15 November 2010 and 14 November 2011. The mean midpoints for spring migration were 3 April 2011 and 20 March 2012 using the geopolitical method and 31 March 2011 and 22 March 2012 using the net displacement method. The duration, initiation date, midpoint, and termination date for both autumn and spring migration did not differ between the two individual level approaches. Although we did not detect differences in migration parameters between the different approaches, the net displacement metric offers broad potential to address questions in movement ecology for migrating species. Ultimately, an objective definition of migration chronology will allow researchers to obtain a comprehensive understanding of the extrinsic factors that drive migration at the individual and population levels. As a result, targeted conservation plans can be developed to support planning for habitat management and evaluation of long-term climate effects.

Development of decision tools to assess migration from plastic materials in contact with food.

PubMed

Gillet, G; Vitrac, O; Tissier, D; Saillard, P; Desobry, S

2009-12-01

Testing the specific migration limits of all substances intentionally added to polymer material according to European Union (EU) regulation is a time-consuming and expensive task. Although mathematical modeling offers an interesting alternative, it can significantly overestimate the migration in situations which are strongly conservative due to significant uncertainty in transport properties. In addition, its application is of little use for end-users or enforcement laboratories, which do not have access to the formulation. This paper revises the paradigm of migration modeling by combining modeling with deformulation experiments and iterative modeling in the framework of decision theory. The complete approach is illustrated for polyolefins in contact with 50% ethanol for eight typical migrants, including hindered phenolic antioxidants and low molecular weight surrogates. Results from a French ACTIA project on the identification of formulation fingerprints and on the prediction of partition coefficients with alcoholic and aqueous stimulants is described. When the true migration was close but still lower than the limit of concern, the proposed compact decision tree, including up to four sources of uncertainty, showed that the chance of demonstrating compliance was about 3 : 4 in the presence of one source of uncertainty, whereas it fell below 2 : 4 and 1 : 4 with two and three sources of uncertainty, respectively. The recommendations for further food packaging safety surveys and future developments are discussed.

A novel functional site of extracellular matrix metalloproteinase inducer (EMMPRIN) that limits the migration of human uterine cervical carcinoma cells.

PubMed

Sato, Takashi; Watanabe, Mami; Hashimoto, Kei; Ota, Tomoko; Akimoto, Noriko; Imada, Keisuke; Nomizu, Motoyoshi; Ito, Akira

2012-01-01

EMMPRIN (extracellular matrix metalloproteinase inducer)/CD147, a membrane-bound glycoprotein with two extracellular loop domains (termed loops I and II), progresses tumor invasion and metastasis by increasing the production of matrix metalloproteinase (MMP) in peritumoral stoma cells. EMMPRIN has also been associated with the control of migration activity in some tumor cells, but little is known about how EMMPRIN regulates tumor cell migration. In the present study, EMMPRIN siRNA suppressed the gene expression and production of EMMPRIN in human uterine cervical carcinoma SKG-II cells. An in vitro scratch wound assay showed enhancement of migration of EMMPRIN-knockdown SKG-II cells. In addition, the SKG-II cell migration was augmented by adding an E. coli-expressed human EMMPRIN mutant with two extracellular loop domains (eEMP-I/II), which bound to the cell surface of SKG-II cells. However, eEMP-I/II suppressed the native EMMPRIN-mediated augmentation of proMMP-1/procollagenase-1 production in a co-culture of the SKG-II cells and human uterine cervical fibroblasts, indicating that the augmentation of SKG-II cell migration resulted from the interference of native EMMPRIN functions by eEMP-I/II on the cell surface. Furthermore, a systematic peptide screening method using nine synthetic EMMPRIN peptides coding the loop I and II domains (termed EM1-9) revealed that EM9 (170HIENLNMEADPGQYR184) facilitated SKG-II cell migration. Moreover, SKG-II cell migration was enhanced by administration of an antibody against EM9, but not EM1 which is a crucial site for the MMP inducible activity of EMMPRIN. Therefore, these results provide novel evidence that EMMPRIN on the cell surface limits the cell migration of human uterine cervical carcinoma cells through 170HIENLNMEADPGQYR184 in the loop II domain. Finally, these results should provide an increased understanding of the functions of EMMPRIN in malignant cervical carcinoma cells, and could contribute to the development of clinical strategies for cervical cancer therapy.

Detection, Characterization and Classification of Biological Components in Aerosols by Time-Resolved Laser Pyrolysis Mass Spectrometry

DTIC Science & Technology

1987-03-20

f ~s yes Noes? no *ram N(choline) K 2 positive ghlo• 1 -i ungi virus? bctcriaip SFigure 2. Tentative... 1 : (a) 15 pg; (b) 150 ng. 30. oneSml(ie m. G 0 JIa O .I-a.l4r TP4OOMM 96W 136 4 0 I. 3 * f "w ’ . 0*0*~q * 󈧣. 6iue16. Cairto uvs-o rccoeae S1 "L l l...U’ SC 3c5 f ______ ____ 20.YD it)I 9c- N= GD4U- - 0- Ln A4?Sue4ug UOf OA140j9Nj = "~ S.. *0-- V) "a C iv c. C .0 0, 04) 00 03 1 . 4 0L= 0 L0 .C6 LJ o

Resolving ultrafast exciton migration in organic solids at the nanoscale

NASA Astrophysics Data System (ADS)

Ginsberg, Naomi

The migration of Frenkel excitons, tightly-bound electron-hole pairs, in photosynthesis and in organic semiconducting films is critical to the efficiency of natural and artificial light harvesting. While these materials exhibit a high degree of structural heterogeneity on the nanoscale, traditional measurements of exciton migration lengths are performed on bulk samples. Since both the characteristic length scales of structural heterogeneity and the reported bulk diffusion lengths are smaller than the optical diffraction limit, we adapt far-field super-resolution fluorescence imaging to uncover the correlations between the structural and energetic landscapes that the excitons explore. By combining the ultrafast super-resolved measurements with exciton hopping simulations we furthermore specify the nature (in addition to the extent) of exciton migration as a function of the intrinsic and ensemble chromophore energy scales that determine a spatio-energetic landscape for migration. In collaboration with: Samuel Penwell, Lucas Ginsberg, University of California, Berkeley and Rodrigo Noriega University of Utah.

[Migration expectations among nursing students in Mexico City].

PubMed

Rosales-Martínez, Yetzi; Nigenda, Gustavo; Galárraga, Omar; Ruiz-Larios, José Arturo

2010-01-01

To analyze the factors associated with the expectations to migrate abroad among nursing students in Mexico City. A cross-sectional study was conducted with a non-random sample of 420 students. A logistic regression model was estimated. A total of 69% of the informants expressed their intention to move abroad, to look for employment (65%) and/or to continue their studies (26%). Of those, 50% would choose Canada as their destination, followed by Spain and the United States. The variables associated with migration expectations were: age, income, having relatives abroad, and perception of poor labor conditions and low wages in Mexico. Results are consistent with international literature. Low wages, poor labor conditions and the limited possibilities for professional development in Mexico are factors that contribute to generate migration expectations among nursing students. Additionally, optimistic perceptions about the job market and the labor demand in more developed countries heighten expectations to migrate.

The Environmental Dimensions of Migration

PubMed Central

Hunter, Lori M.; Luna, Jessie K.; Norton, Rachel M.

2017-01-01

Research on the environmental dimensions of human migration has made important strides in recent years. However, findings have been spread across multiple disciplines with wide ranging methodologies and limited theoretical development. This article reviews key findings of the field and identifies future directions for sociological research. We contend that the field has moved beyond linear environmental “push” theories towards a greater integration of context, including micro-, meso-, and macro-level interactions. We highlight findings that migration is often a household strategy to diversify risk (NELM), interacting with household composition, individual characteristics, social networks, and historical, political and economic contexts. We highlight promising developments in the field, including the recognition that migration is a long-standing form of environmental adaptation and yet only one among many forms of adaptation. Finally, we argue that sociologists could contribute significantly to migration-environment inquiry through attention to issues of inequality, perceptions, and agency vis-à-vis structure. PMID:29861536

New evidence on the effects of international migration on the risk of low birthweight in Mexico.

PubMed

Sunil, Thankam S; Flores, Miguel; Garcia, Ginny E

2012-04-01

The purpose of this article is to provide new empirical evidence linking migration of Mexican households to the USA with infant health outcomes. By using new data for Mexico, the Encuesta Nacional de la Dinamica Demografica 2006, this research focuses on the effect of migration on birth weight. Multivariate logistic regression methods are used to model low birth weight (LBW) as a function of a set of proximate, intermediate and socioeconomic determinants. In analyzing the channels through which migration affects birth outcomes, the findings provide no conclusive evidence for remittances as the only mechanism associated with lowering the odds of LBW. Given the limitations of the data, the study results showed new empirical evidence explaining the significance of both financial and social remittances associated with international migration and infant health outcomes in Mexico. © 2010 Blackwell Publishing Ltd.

Limitations and mechanisms influencing the migratory performance of soaring birds

Treesearch

Tricia A. Miller; Brooks Robert P.; Michael J. Lanzone; David Brandes; Jeff Cooper; Junior A. Tremblay; Jay Wilhelm; Adam Duerr; Todd E. Katzner

2016-01-01

Migration is costly in terms of time, energy and safety. Optimal migration theory suggests that individual migratory birds will choose between these three costs depending on their motivation and available resources. To test hypotheses about use of migratory strategies by large soaring birds, we used GPS telemetry to track 18 adult, 13 sub-adult and 15 juvenile Golden...

Maturation State and Matrix Microstructure Regulate Interstitial Cell Migration in Dense Connective Tissues.

PubMed

Qu, Feini; Li, Qing; Wang, Xiao; Cao, Xuan; Zgonis, Miltiadis H; Esterhai, John L; Shenoy, Vivek B; Han, Lin; Mauck, Robert L

2018-02-19

Few regenerative approaches exist for the treatment of injuries to adult dense connective tissues. Compared to fetal tissues, adult connective tissues are hypocellular and show limited healing after injury. We hypothesized that robust repair can occur in fetal tissues with an immature extracellular matrix (ECM) that is conducive to cell migration, and that this process fails in adults due to the biophysical barriers imposed by the mature ECM. Using the knee meniscus as a platform, we evaluated the evolving micromechanics and microstructure of fetal and adult tissues, and interrogated the interstitial migratory capacity of adult meniscal cells through fetal and adult tissue microenvironments with or without partial enzymatic digestion. To integrate our findings, a computational model was implemented to determine how changing biophysical parameters impact cell migration through these dense networks. Our results show that the micromechanics and microstructure of the adult meniscus ECM sterically hinder cell mobility, and that modulation of these ECM attributes via an exogenous matrix-degrading enzyme permits migration through this otherwise impenetrable network. By addressing the inherent limitations to repair imposed by the mature ECM, these studies may define new clinical strategies to promote repair of damaged dense connective tissues in adults.

Sources of international migration statistics in Africa.

PubMed

1984-01-01

The sources of international migration data for Africa may be classified into 2 main categories: administrative records and 2) censuses and survey data. Both categories are sources for the direct measurement of migration, but the 2nd category can be used for the indirect estimation of net international migration. The administrative records from which data on international migration may be derived include 1) entry/departure cards or forms completed at international borders, 2) residence/work permits issued to aliens, and 3) general population registers and registers of aliens. The statistics derived from the entry/departure cards may be described as 1) land frontier control statistics and 2) port control statistics. The former refer to data derived from movements across land borders and the latter refer to information collected at international airports and seaports. Other administrative records which are potential sources of statistics on international migration in some African countries include some limited population registers, records of the registration of aliens, and particulars of residence/work permits issued to aliens. Although frontier control data are considered the most important source of international migration statistics, in many African countries these data are too deficient to provide a satisfactory indication of the level of international migration. Thus decennial population censuses and/or sample surveys are the major sources of the available statistics on the stock and characteristics of international migration. Indirect methods can be used to supplement census data with intercensal estimates of net migration using census data on the total population. This indirect method of obtaining information on migration can be used to evaluate estimates derived from frontier control records, and it also offers the means of obtaining alternative information on international migration in African countries which have not directly investigated migration topics in their censuses or surveys.

Electrolytic cell stack with molten electrolyte migration control

DOEpatents

Kunz, H. Russell; Guthrie, Robin J.; Katz, Murray

1988-08-02

An electrolytic cell stack includes inactive electrolyte reservoirs at the upper and lower end portions thereof. The reservoirs are separated from the stack of the complete cells by impermeable, electrically conductive separators. Reservoirs at the negative end are initially low in electrolyte and the reservoirs at the positive end are high in electrolyte fill. During stack operation electrolyte migration from the positive to the negative end will be offset by the inactive reservoir capacity. In combination with the inactive reservoirs, a sealing member of high porosity and low electrolyte retention is employed to limit the electrolyte migration rate.

Electrolytic cell stack with molten electrolyte migration control

DOEpatents

Kunz, H.R.; Guthrie, R.J.; Katz, M.

1987-03-17

An electrolytic cell stack includes inactive electrolyte reservoirs at the upper and lower end portions thereof. The reservoirs are separated from the stack of the complete cells by impermeable, electrically conductive separators. Reservoirs at the negative end are initially low in electrolyte and the reservoirs at the positive end are high in electrolyte fill. During stack operation electrolyte migration from the positive to the negative end will be offset by the inactive reservoir capacity. In combination with the inactive reservoirs, a sealing member of high porosity and low electrolyte retention is employed to limit the electrolyte migration rate. 5 figs.

Emigration from China in Comparative Perspective*

PubMed Central

Lu, Yao; Liang, Zai; Chunyu, Miao David

2014-01-01

Comparative research on international migration has increasingly focused on immigrant integration rather than the process of emigration. By investigating the different streams of Chinese migration to the United States and Europe, as well as the different stages of Chinese migration to the U.S., this study examines the way in which both receiving and sending contexts combine to shape the process of emigration. Using data from a 2002–2003 survey of emigration from China’s Fujian Province, we demonstrate that under restrictive exit and entry policies and high barriers to migration (i.e., clandestine migration from Fuzhou to the U.S.), resources such as migrant social capital, political capital (cadre resources), and human capital all play a crucial role in the emigration process. However, the roles of these resources in the migration process are limited when migration barriers are sufficiently low and when local governments adopt proactive policies promoting emigration (i.e., legal migration from Mingxi to Europe). Comparisons over time suggest that the importance of migrant social capital, political capital, and human capital has strongly persisted for Fuzhou-US emigration, as a result of tightening exit and entry policies. Despite these marked differences between Fuzhou and Mingxi emigration, the results also point to two general processes that are highly consistent across settings and over time—the cumulative causation of migration and the advantage conferred by traditional positional power (cadre status). PMID:26146414

Myth-free space advocacy part I-The myth of innate exploratory and migratory urges

NASA Astrophysics Data System (ADS)

Schwartz, James S. J.

2017-08-01

This paper discusses the ;myth; that we have an innate drive to explore or to migrate into space. Three interpretations of the claim are considered. According to the ;mystical interpretation,; it is part of our ;destiny; as humans to explore and migrate into space. Such a claim has no rational basis and should play no role in rationally- or evidence-based space advocacy. According to the ;cultural interpretation,; exploration and migration are essential features of human culture and society. These are not universal features because there are cultures and societies that have not encouraged exploration and migration. Moreover, the cultures that have explored have seldom conducted exploration for its own sake. According to the ;biological interpretation; there is a psychological or genetic basis for exploration or migration. While there is limited genetic evidence for such a claim, that evidence suggests that genes associated with exploratory behavior were selected for subsequent to migration, making it unlikely that these genes played a role in causing migration. In none of these senses is it clearly true that we have an innate drive to explore or migrate into space; and even if we did it would be fallacious to argue that the existence of such a drive justified spaceflight activities.

Controls on drainage divide migration in the northern Sierras Pampeanas assessed through morphometric indicators

NASA Astrophysics Data System (ADS)

Seagren, E. G.; Schoenbohm, L. M.

2017-12-01

Drainage reorganization, primarily through progressive divide migration leading to discrete stream captures, is increasingly recognized as a common phenomenon during mountain-building events. This drainage rearrangement reflects complex interactions between tectonics, climate, and lithology, and can fundamentally change erosion and sedimentation patterns; therefore, determining the spatial extent and potential controls of divide migration is vital to understanding the topographic evolution of orogenic landscapes. Both geomorphic and morphometric evidence can be used to identify such drainage reorganization. The northern Sierras Pampeanas is an ideal location in which to study divide migration as limited glaciation and low out-of-channel erosion rates preserve evidence of reorganization. Additionally, several ranges in the region, such as Sierra de las Planchadas, exhibit geomorphic evidence of drainage rearrangement, including wind gaps and hairpin turns. Using ArcGIS, LSDTopoTools, and TopoToolbox, we conducted a systematic analysis of the spatial distribution of three morphometric indicators of divide migration: χ, Mx, and local headwater relief. Local `hotspots' undergoing drainage divide migration were identified using spatial autocorrelation and clustering methods - Gi* and Moran's I. Using spatial regression analysis, we assessed the potential controls of lithology, modern TRMM precipitation rates, and tectonics over divide migration. Preliminary results suggest broad westward migration of main drainage divides, following both the orographic precipitation gradient and regional slope.

Migration of nanoparticles from plastic packaging materials containing carbon black into foodstuffs

PubMed Central

Bott, Johannes; Störmer, Angela; Franz, Roland

2014-01-01

Carbon black was investigated to assess and quantify the possibility that nanoparticles might migrate out of plastic materials used in the food packaging industry. Two types of carbon black were incorporated in low-density polyethylene (LDPE) and polystyrene (PS) at 2.5% and 5.0% loading (w/w), and then subjected to migration studies. The samples were exposed to different food simulants according to European Union Plastics Regulation 10/2011, simulating long-term storage with aqueous and fatty foodstuffs. Asymmetric flow field-flow fractionation (AF4) coupled to a multi-angle laser light-scattering (MALLS) detector was used to separate, characterise and quantify the potential release of nanoparticles. The AF4 method was successful in differentiating carbon black from other matrix components, such as extracted polymer chains, in the migration solution. At a detection limit of 12 µg kg−1, carbon black did not migrate from the packaging material into food simulants. The experimental findings are in agreement with theoretical considerations based on migration modelling. From both the experimental findings and theoretical considerations, it can be concluded that carbon black does not migrate into food once it is incorporated into a plastics food contact material. PMID:25105506

Migration of nanoparticles from plastic packaging materials containing carbon black into foodstuffs.

PubMed

Bott, Johannes; Störmer, Angela; Franz, Roland

2014-01-01

Carbon black was investigated to assess and quantify the possibility that nanoparticles might migrate out of plastic materials used in the food packaging industry. Two types of carbon black were incorporated in low-density polyethylene (LDPE) and polystyrene (PS) at 2.5% and 5.0% loading (w/w), and then subjected to migration studies. The samples were exposed to different food simulants according to European Union Plastics Regulation 10/2011, simulating long-term storage with aqueous and fatty foodstuffs. Asymmetric flow field-flow fractionation (AF4) coupled to a multi-angle laser light-scattering (MALLS) detector was used to separate, characterise and quantify the potential release of nanoparticles. The AF4 method was successful in differentiating carbon black from other matrix components, such as extracted polymer chains, in the migration solution. At a detection limit of 12 µg kg⁻¹, carbon black did not migrate from the packaging material into food simulants. The experimental findings are in agreement with theoretical considerations based on migration modelling. From both the experimental findings and theoretical considerations, it can be concluded that carbon black does not migrate into food once it is incorporated into a plastics food contact material.

Hypoxia Regulates mTORC1-Mediated Keratinocyte Motility and Migration via the AMPK Pathway

PubMed Central

Yan, Tiantian; Zhang, Junhui; Tang, Di; Zhang, Xingyue; Jiang, Xupin; Zhao, Liping; Zhang, Qiong; Zhang, Dongxia; Huang, Yuesheng

2017-01-01

Keratinocyte migration, the initial event and rate-limiting step in wound healing, plays a vital role in restoration of the intact skin barrier, also known as re-epithelialization. After acute tissue injury, hypoxic microenvironment gradually develops and acts as an early stimulus to initiate the healing process. Although we have previously found that hypoxia induces keratinocyte migration, the underlying mechanism remains unknown. Here, we first observed that hypoxia increased mTORC1 activity. Recombinant lentivirus vector and Rapamycin were used for silencing mTORC1 in HaCaT cells and primary mouse keratinocytes (MKs). Using cell migration assay and a Zeiss chamber equipped with imaging system, we also demonstrated that mTORC1 downregulation reversed hypoxia-induced keratinocyte motility and lateral migration. Importantly, hypoxia-activated mTORC1 was accompanied by the AMPK downregulation, and we found that the AMPK pathway activators Metformin (Met) and 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) decreased the mTORC1 activity, cell motility and lateral migration. Thus, our results suggest that hypoxia regulates mTORC1-mediated keratinocyte motility and migration via the AMPK pathway. PMID:28068384

Asymmetry of Radial and Symmetry of Tangential Neuronal Migration Pathways in Developing Human Fetal Brains

PubMed Central

Miyazaki, Yuta; Song, Jae W.; Takahashi, Emi

2016-01-01

The radial and tangential neural migration pathways are two major neuronal migration streams in humans that are critical during corticogenesis. Corticogenesis is a complex process of neuronal proliferation that is followed by neuronal migration and the formation of axonal connections. Existing histological assessments of these two neuronal migration pathways have limitations inherent to microscopic studies and are confined to small anatomic regions of interest (ROIs). Thus, little evidence is available about their three-dimensional (3-D) fiber pathways and development throughout the entire brain. In this study, we imaged and analyzed radial and tangential migration pathways in the whole human brain using high-angular resolution diffusion MR imaging (HARDI) tractography. We imaged ten fixed, postmortem fetal (17 gestational weeks (GW), 18 GW, 19 GW, three 20 GW, three 21 GW and 22 GW) and eight in vivo newborn (two 30 GW, 34 GW, 35 GW and four 40 GW) brains with no neurological/pathological conditions. We statistically compared the volume of the left and right radial and tangential migration pathways, and the volume of the radial migration pathways of the anterior and posterior regions of the brain. In specimens 22 GW or younger, the volume of radial migration pathways of the left hemisphere was significantly larger than that of the right hemisphere. The volume of posterior radial migration pathways was also larger when compared to the anterior pathways in specimens 22 GW or younger. In contrast, no significant differences were observed in the radial migration pathways of brains older than 22 GW. Moreover, our study did not identify any significant differences in volumetric laterality in the tangential migration pathways. These results suggest that these two neuronal migration pathways develop and regress differently, and radial neuronal migration varies regionally based on hemispheric and anterior-posterior laterality, potentially explaining regional differences in the amount of excitatory neurons that migrate along the radial scaffold. PMID:26834572

Migration trends of Sockeye Salmon at the northern edge of their distribution

USGS Publications Warehouse

Carey, Michael P.; Zimmerman, Christian E.; Keith, Kevin D.; Schelske, Merlyn; Lean, Charles; Douglas, David C.

2017-01-01

Climate change is affecting arctic and subarctic ecosystems, and anadromous fish such as Pacific salmon Oncorhynchus spp. are particularly susceptible due to the physiological challenge of spawning migrations. Predicting how migratory timing will change under Arctic warming scenarios requires an understanding of how environmental factors drive salmon migrations. Multiple mechanisms exist by which environmental conditions may influence migrating salmon, including altered migration cues from the ocean and natal river. We explored relationships between interannual variability and annual migration timing (2003–2014) of Sockeye Salmon O. nerka in a subarctic watershed with environmental conditions at broad, intermediate, and local spatial scales. Low numbers of Sockeye Salmon have returned to this high-latitude watershed in recent years, and run size has been a dominant influence on the migration duration and the midpoint date of the run. The duration of the migration upriver varied by as much as 25 d across years, and shorter run durations were associated with smaller run sizes. The duration of the migration was also extended with warmer sea surface temperatures in the staging area and lower values of the North Pacific Index. The midpoint date of the total run was earlier when the run size was larger, whereas the midpoint date was delayed during years in which river temperatures warmed earlier in the season. Documenting factors related to the migration of Sockeye Salmon near the northern limit of their range provides insights into the determinants of salmon migrations and suggests processes that could be important for determining future changes in arctic and subarctic ecosystems.

Seismic imaging of the Waltham Canyon fault, California: comparison of ray‐theoretical and Fresnel volume prestack depth migration

USGS Publications Warehouse

Bauer, Klaus; Ryberg, Trond; Fuis, Gary S.; Lüth, Stefan

2013-01-01

Near‐vertical faults can be imaged using reflected refractions identified in controlled‐source seismic data. Often theses phases are observed on a few neighboring shot or receiver gathers, resulting in a low‐fold data set. Imaging can be carried out with Kirchhoff prestack depth migration in which migration noise is suppressed by constructive stacking of large amounts of multifold data. Fresnel volume migration can be used for low‐fold data without severe migration noise, as the smearing along isochrones is limited to the first Fresnel zone around the reflection point. We developed a modified Fresnel volume migration technique to enhance imaging of steep faults and to suppress noise and undesired coherent phases. The modifications include target‐oriented filters to separate reflected refractions from steep‐dipping faults and reflections with hyperbolic moveout. Undesired phases like multiple reflections, mode conversions, direct P and S waves, and surface waves are suppressed by these filters. As an alternative approach, we developed a new prestack line‐drawing migration method, which can be considered as a proxy to an infinite frequency approximation of the Fresnel volume migration. The line‐drawing migration is not considering waveform information but requires significantly shorter computational time. Target‐oriented filters were extended by dip filters in the line‐drawing migration method. The migration methods were tested with synthetic data and applied to real data from the Waltham Canyon fault, California. The two techniques are applied best in combination, to design filters and to generate complementary images of steep faults.

The extra mile: Ungulate migration distance alters the use of seasonal range and exposure to anthropogenic risk

USGS Publications Warehouse

Sawyer, Hall; Middleton, Arthur D.; Hayes, Matthew M.; Kauffman, Matthew J.; Monteith, Kevin L.

2016-01-01

Partial migration occurs across a variety of taxa and has important ecological and evolutionary consequences. Among ungulates, studies of partially migratory populations have allowed researchers to compare and contrast performance metrics of migrants versus residents and examine how environmental factors influence the relative abundance of each. Such studies tend to characterize animals discretely as either migratory or resident, but we suggest that variable migration distances within migratory herds are an important and overlooked form of population structure, with potential consequences for animal fitness. We examined whether the variation in individual migration distances (20–264 km) within a single wintering population of mule deer (Odocoileus hemionus) was associated with several critical behavioral attributes of migration, including timing of migration, time allocation to seasonal ranges, and exposure to anthropogenic mortality risks. Both the timing of migration and the amount of time animals allocated to seasonal ranges varied with migration distance. Animals migrating long distances (150–250 km) initiated spring migration more than three weeks before than those migrating moderate (50–150 km) or short distances (<50 km). Across an entire year, long-distance migrants spent approximately 100 more days migrating compared to moderate- and short-distance migrants. Relatedly, winter residency of long-distance migrants was 71 d fewer than for animals migrating shorter distances. Exposure to anthropogenic mortality factors, including highways and fences, was high for long-distance migrants, whereas vulnerability to harvest was high for short- and moderate-distance migrants. By reducing the amount of time that animals spend on winter range, long-distance migration may alleviate intraspecific competition for limited forage and effectively increase carrying capacity. Clear differences in winter residency, migration duration, and risk of anthropogenic mortality among short-, moderate-, and long-distance migrants suggest fitness trade-offs may exist among migratory segments of the population. Future studies of partial migration may benefit from expanding comparisons of residents and migrants, to consider how variable migration distances of migrants may influence the costs and benefits of migration.

Effects of Radiation on Metastasis and Tumor Cell Migration

PubMed Central

Vilalta, Marta; Rafat, Marjan; Graves, Edward E.

2016-01-01

It is well known that tumor cells migrate from the primary lesion to distant sites to form metastases and that these lesions limit patient outcome in a majority of cases. However the extent to which radiation influences this process and to which migration in turn alters radiation response remains controversial. There are preclinical and clinical reports showing that focal radiotherapy can both increase the development of distant metastasis, as well as that it can induce the regression of established metastases through the abscopal effect. More recently, preclinical studies have suggested that radiation can attract migrating tumor cells and may thereby facilitate tumor recurrence. In this review, we summarize these phenomena and their potential mechanisms of action, and evaluate their significance for modern radiation therapy strategies. PMID:27022944

Optimal chemotaxis in intermittent migration of animal cells

NASA Astrophysics Data System (ADS)

Romanczuk, P.; Salbreux, G.

2015-04-01

Animal cells can sense chemical gradients without moving and are faced with the challenge of migrating towards a target despite noisy information on the target position. Here we discuss optimal search strategies for a chaser that moves by switching between two phases of motion ("run" and "tumble"), reorienting itself towards the target during tumble phases, and performing persistent migration during run phases. We show that the chaser average run time can be adjusted to minimize the target catching time or the spatial dispersion of the chasers. We obtain analytical results for the catching time and for the spatial dispersion in the limits of small and large ratios of run time to tumble time and scaling laws for the optimal run times. Our findings have implications for optimal chemotactic strategies in animal cell migration.

Exploring the Thermal Limits of IR-Based Automatic Whale Detection (ETAW)

DTIC Science & Technology

2013-09-30

the northward humpback whale migration, which occurs annually rather close to shore near North Stradbroke Island, Queensland, Australia. Based on the...successive northward humpback whale migrations and collecting concurrent independent (double blind) visual observations (modified cue counting), a... Whale Detection (ETAW) Olaf Boebel P.O. Box 120161 27515 Bremerhaven Germany phone: +49 (471) 4831-1879 fax: +49 (471) 4831-1797 email

Investigation of particle inertial migration in high particle concentration suspension flow by multi-electrodes sensing and Eulerian-Lagrangian simulation in a square microchannel

PubMed Central

Zhao, Tong; Liu, Kai; Takei, Masahiro

2016-01-01

The inertial migration of neutrally buoyant spherical particles in high particle concentration (αpi > 3%) suspension flow in a square microchannel was investigated by means of the multi-electrodes sensing method which broke through the limitation of conventional optical measurement techniques in the high particle concentration suspensions due to interference from the large particle numbers. Based on the measured particle concentrations near the wall and at the corner of the square microchannel, particle cross-sectional migration ratios are calculated to quantitatively estimate the migration degree. As a result, particle migration to four stable equilibrium positions near the centre of each face of the square microchannel is found only in the cases of low initial particle concentration up to 5.0 v/v%, while the migration phenomenon becomes partial as the initial particle concentration achieves 10.0 v/v% and disappears in the cases of the initial particle concentration αpi ≥ 15%. In order to clarify the influential mechanism of particle-particle interaction on particle migration, an Eulerian-Lagrangian numerical model was proposed by employing the Lennard-Jones potential as the inter-particle potential, while the inertial lift coefficient is calculated by a pre-processed semi-analytical simulation. Moreover, based on the experimental and simulation results, a dimensionless number named migration index was proposed to evaluate the influence of the initial particle concentration on the particle migration phenomenon. The migration index less than 0.1 is found to denote obvious particle inertial migration, while a larger migration index denotes the absence of it. This index is helpful for estimation of the maximum initial particle concentration for the design of inertial microfluidic devices. PMID:27158288

The evolution of immunity in relation to colonization and migration.

PubMed

O'Connor, Emily A; Cornwallis, Charlie K; Hasselquist, Dennis; Nilsson, Jan-Åke; Westerdahl, Helena

2018-05-01

Colonization and migration have a crucial effect on patterns of biodiversity, with disease predicted to play an important role in these processes. However, evidence of the effect of pathogens on broad patterns of colonization and migration is limited. Here, using phylogenetic analyses of 1,311 species of Afro-Palaearctic songbirds, we show that colonization events from regions of high (sub-Saharan Africa) to low (the Palaearctic) pathogen diversity were up to 20 times more frequent than the reverse, and that migration has evolved 3 times more frequently from African- as opposed to Palaearctic-resident species. We also found that resident species that colonized the Palaearctic from Africa, as well as African species that evolved long-distance migration to breed in the Palaearctic, have reduced diversity of key immune genes associated with pathogen recognition (major histocompatibility complex class I). These results suggest that changes in the pathogen community that occur during colonization and migration shape the evolution of the immune system, potentially by adjusting the trade-off between the benefits of extensive pathogen recognition and the costs of immunopathology that result from high major histocompatibility complex class I diversity.

HIV Prevention among Mexican Migrants at Different Migration Phases: Exposure to Prevention Messages and Association With Testing Behaviors

PubMed Central

Martinez-Donate, Ana P.; Rangel, M. Gudelia; Zhang, Xiao; Simon, Norma-Jean; Rhoads, Natalie; Gonzalez-Fagoaga, J. Eduardo; Gonzalez, Ahmed Asadi

2016-01-01

Mobile populations are at increased risk for HIV infection. Exposure to HIV prevention messages at all phases of the migration process may help decrease im/migrants’ HIV risk. We investigated levels of exposure to HIV prevention messages, factors associated with message exposure, and the association between exposure to prevention messages and HIV testing behavior among Mexican im/migrants at different phases of the migration process. We conducted a cross-sectional, probability survey of Mexican im/migrants (N=3,149) traveling through the border city of Tijuana, Mexico. The results indicate limited exposure to prevention messages (57%–75%) and suboptimal last 12-month HIV testing rates (14%–25%) across five migration phases. Compared to pre-departure levels (75%), exposure to messages decreases at all post-departure migration phases (57%–63%, p<.001). In general, exposure to prevention messages is positively associated with greater odds of HIV testing at the pre-departure, destination, and interception phases. Binational efforts need to be intensified to reach and deliver HIV prevention to Mexican im/migrants across the migration continuum. PMID:26595267

Migration and Extension of Solar Active Longitudinal Zones

NASA Astrophysics Data System (ADS)

Gyenge, N.; Baranyi, T.; Ludmány, A.

2014-02-01

Solar active longitudes show a characteristic migration pattern in the Carrington coordinate system if they can be identified at all. By following this migration, the longitudinal activity distribution around the center of the band can be determined. The half-width of the distribution is found to be varying in Cycles 21 - 23, and in some time intervals it was as narrow as 20 - 30 degrees. It was more extended around a maximum but it was also narrow when the activity jumped to the opposite longitude. Flux emergence exhibited a quasi-periodic variation within the active zone with a period of about 1.3 years. The path of the active-longitude migration does not support the view that it might be associated with the 11-year solar cycle. These results were obtained for a limited time interval of a few solar cycles and, bearing in mind uncertainties of the migration-path definition, are only indicative. For the major fraction of the dataset no systematic active longitudes were found. Sporadic migration of active longitudes was identified only for Cycles 21 - 22 in the northern hemisphere and Cycle 23 in the southern hemisphere.

The international migration of nurses in long-term care.

PubMed

Redfoot, Donald L; Houser, Ari N

2008-01-01

This article describes five major factors that are affecting patterns of international migration among nurses who work in long-term care settings: DEMOGRAPHIC DRIVERS: The aging of the populations in developed countries and the low to negative growth in the working-age population will increase the demand for international workers to provide long-term care services. GENDER AND RACE: A dual labor market of long-term care workers, increasingly made up of women of color, is becoming internationalized by the employment of migrating nurses from developing countries. CREDENTIALING: The process of credentialing skilled workers creates barriers to entry for migrating nurses and leads to "decredentialing" where registered nurses work as licensed practical nurses or aides. COLONIAL HISTORY AND GEOGRAPHY: The colonial histories of many European countries and the United States have increased migration from former colonies in developing countries to former colonial powers. WORKER RECRUITMENT: Efforts to limit the recruitment of health care workers from some developing countries have had little effect on migration, in part because much of the recruitment comes through informal channels of family and friends.

Ancient Human Migrations to and through Jammu Kashmir- India were not of Males Exclusively.

PubMed

Sharma, Indu; Sharma, Varun; Khan, Akbar; Kumar, Parvinder; Rai, Ekta; Bamezai, Rameshwar N K; Vilar, Miguel; Sharma, Swarkar

2018-01-16

Jammu and Kashmir (J&K), the Northern most State of India, has been under-represented or altogether absent in most of the phylogenetic studies carried out in literature, despite its strategic location in the Himalayan region. Nonetheless, this region may have acted as a corridor to various migrations to and from mainland India, Eurasia or northeast Asia. The belief goes that most of the migrations post-late-Pleistocene were mainly male dominated, primarily associated with population invasions, where female migration may thus have been limited. To evaluate female-centered migration patterns in the region, we sequenced 83 complete mitochondrial genomes of unrelated individuals belonging to different ethnic groups from the state. We observed a high diversity in the studied maternal lineages, identifying 19 new maternal sub-haplogroups (HGs). High maternal diversity and our phylogenetic analyses suggest that the migrations post-Pleistocene were not strictly paternal, as described in the literature. These preliminary observations highlight the need to carry out an extensive study of the endogamous populations of the region to unravel many facts and find links in the peopling of India.

Time-domain least-squares migration using the Gaussian beam summation method

NASA Astrophysics Data System (ADS)

Yang, Jidong; Zhu, Hejun; McMechan, George; Yue, Yubo

2018-04-01

With a finite recording aperture, a limited source spectrum and unbalanced illumination, traditional imaging methods are insufficient to generate satisfactory depth profiles with high resolution and high amplitude fidelity. This is because traditional migration uses the adjoint operator of the forward modeling rather than the inverse operator. We propose a least-squares migration approach based on the time-domain Gaussian beam summation, which helps to balance subsurface illumination and improve image resolution. Based on the Born approximation for the isotropic acoustic wave equation, we derive a linear time-domain Gaussian beam modeling operator, which significantly reduces computational costs in comparison with the spectral method. Then, we formulate the corresponding adjoint Gaussian beam migration, as the gradient of an L2-norm waveform misfit function. An L1-norm regularization is introduced to the inversion to enhance the robustness of least-squares migration, and an approximated diagonal Hessian is used as a preconditioner to speed convergence. Synthetic and field data examples demonstrate that the proposed approach improves imaging resolution and amplitude fidelity in comparison with traditional Gaussian beam migration.

Time-domain least-squares migration using the Gaussian beam summation method

NASA Astrophysics Data System (ADS)

Yang, Jidong; Zhu, Hejun; McMechan, George; Yue, Yubo

2018-07-01

With a finite recording aperture, a limited source spectrum and unbalanced illumination, traditional imaging methods are insufficient to generate satisfactory depth profiles with high resolution and high amplitude fidelity. This is because traditional migration uses the adjoint operator of the forward modelling rather than the inverse operator. We propose a least-squares migration approach based on the time-domain Gaussian beam summation, which helps to balance subsurface illumination and improve image resolution. Based on the Born approximation for the isotropic acoustic wave equation, we derive a linear time-domain Gaussian beam modelling operator, which significantly reduces computational costs in comparison with the spectral method. Then, we formulate the corresponding adjoint Gaussian beam migration, as the gradient of an L2-norm waveform misfit function. An L1-norm regularization is introduced to the inversion to enhance the robustness of least-squares migration, and an approximated diagonal Hessian is used as a pre-conditioner to speed convergence. Synthetic and field data examples demonstrate that the proposed approach improves imaging resolution and amplitude fidelity in comparison with traditional Gaussian beam migration.

The role of the antioxidant system during intense endurance exercise: lessons from migrating birds.

PubMed

Cooper-Mullin, Clara; McWilliams, Scott R

2016-12-01

During migration, birds substantially increase their metabolic rate and burn fats as fuel and yet somehow avoid succumbing to overwhelming oxidative damage. The physiological means by which vertebrates such as migrating birds can counteract an increased production of reactive species (RS) are rather limited: they can upregulate their endogenous antioxidant system and/or consume dietary antioxidants (prophylactically or therapeutically). Thus, birds can alter different components of their antioxidant system to respond to the demands of long-duration flights, but much remains to be discovered about the complexities of RS production and antioxidant protection throughout migration. Here, we use bird migration as an example to discuss how RS are produced during endurance exercise and how the complex antioxidant system can protect against cellular damage caused by RS. Understanding how a bird's antioxidant system responds during migration can lend insights into how antioxidants protect birds during other life-history stages when metabolic rate may be high, and how antioxidants protect other vertebrates from oxidative damage during endurance exercise. © 2016. Published by The Company of Biologists Ltd.

Development and validation of an automated and marker-free CT-based spatial analysis method (CTSA) for assessment of femoral hip implant migration: In vitro accuracy and precision comparable to that of radiostereometric analysis (RSA).

PubMed

Scheerlinck, Thierry; Polfliet, Mathias; Deklerck, Rudi; Van Gompel, Gert; Buls, Nico; Vandemeulebroucke, Jef

2016-01-01

We developed a marker-free automated CT-based spatial analysis (CTSA) method to detect stem-bone migration in consecutive CT datasets and assessed the accuracy and precision in vitro. Our aim was to demonstrate that in vitro accuracy and precision of CTSA is comparable to that of radiostereometric analysis (RSA). Stem and bone were segmented in 2 CT datasets and both were registered pairwise. The resulting rigid transformations were compared and transferred to an anatomically sound coordinate system, taking the stem as reference. This resulted in 3 translation parameters and 3 rotation parameters describing the relative amount of stem-bone displacement, and it allowed calculation of the point of maximal stem migration. Accuracy was evaluated in 39 comparisons by imposing known stem migration on a stem-bone model. Precision was estimated in 20 comparisons based on a zero-migration model, and in 5 patients without stem loosening. Limits of the 95% tolerance intervals (TIs) for accuracy did not exceed 0.28 mm for translations and 0.20° for rotations (largest standard deviation of the signed error (SD(SE)): 0.081 mm and 0.057°). In vitro, limits of the 95% TI for precision in a clinically relevant setting (8 comparisons) were below 0.09 mm and 0.14° (largest SD(SE): 0.012 mm and 0.020°). In patients, the precision was lower, but acceptable, and dependent on CT scan resolution. CTSA allows detection of stem-bone migration with an accuracy and precision comparable to that of RSA. It could be valuable for evaluation of subtle stem loosening in clinical practice.

Analysis of PVC plasticizers in medical devices and infused solutions by GC-MS.

PubMed

Bourdeaux, Daniel; Yessaad, Mouloud; Chennell, Philip; Larbre, Virginie; Eljezi, Teuta; Bernard, Lise; Sautou, Valerie

2016-01-25

In 2008, di-(2-ethylhexyl) phthalate (DEHP), was categorized as CMR 1B under the CLP regulations and its use in PVC medical devices (MD) was called into question by the European authorities. This resulted in the commercialization of PVC MDs plasticized with the DEHP alternative plasticizers tri-octyl trimellitate (TOTM), di-(2-ethylhexyl) terephthalate (DEHT), di-isononyl cyclohexane-1,2-dicarboxylate (DINCH), di-isononyl phthalate (DINP), di-(2-ethylhexy) adipate (DEHA), and Acetyl tri-n-butyl citrate (ATBC). The data available on the migration of these plasticizers from the MDs are too limited to ensure their safe use. We therefore developed a versatile GC-MS method to identify and quantify both these newly used plasticizers and DEHP in MDs and to assess their migration abilities in simulant solution. The use of cubic calibration curves and the optimization of the analytical method by an experimental plan allowed us to lower the limit of plasticizer quantification. It also allowed wide calibration curves to be established that were adapted to this quantification in MDs during migration tests, irrespective of the amount present, and while maintaining good precision and accuracy. We then tested the developed method on 32 PVC MDs used in our hospital and evaluated the plasticizer release from a PVC MD into a simulant solution during a 24h migration test. The results showed a predominance of TOTM in PVC MDs accompanied by DEHP (<0.1% w/w), DEHT, and sometimes DEHA. The migration tests showed a difference in the migration ability between the plasticizers and a non-linear kinetic release. Copyright © 2015 Elsevier B.V. All rights reserved.

Population Genetic Analysis Infers Migration Pathways of Phytophthora ramorum in US Nurseries

PubMed Central

Goss, Erica M.; Larsen, Meg; Chastagner, Gary A.; Givens, Donald R.; Grünwald, Niklaus J.

2009-01-01

Recently introduced, exotic plant pathogens may exhibit low genetic diversity and be limited to clonal reproduction. However, rapidly mutating molecular markers such as microsatellites can reveal genetic variation within these populations and be used to model putative migration patterns. Phytophthora ramorum is the exotic pathogen, discovered in the late 1990s, that is responsible for sudden oak death in California forests and ramorum blight of common ornamentals. The nursery trade has moved this pathogen from source populations on the West Coast to locations across the United States, thus risking introduction to other native forests. We examined the genetic diversity of P. ramorum in United States nurseries by microsatellite genotyping 279 isolates collected from 19 states between 2004 and 2007. Of the three known P. ramorum clonal lineages, the most common and genetically diverse lineage in the sample was NA1. Two eastward migration pathways were revealed in the clustering of NA1 isolates into two groups, one containing isolates from Connecticut, Oregon, and Washington and the other isolates from California and the remaining states. This finding is consistent with trace forward analyses conducted by the US Department of Agriculture's Animal and Plant Health Inspection Service. At the same time, genetic diversities in several states equaled those observed in California, Oregon, and Washington and two-thirds of multilocus genotypes exhibited limited geographic distributions, indicating that mutation was common during or subsequent to migration. Together, these data suggest that migration, rapid mutation, and genetic drift all play a role in structuring the genetic diversity of P. ramorum in US nurseries. This work demonstrates that fast-evolving genetic markers can be used to examine the evolutionary processes acting on recently introduced pathogens and to infer their putative migration patterns, thus showing promise for the application of forensics to plant pathogens. PMID:19774068

Simultaneous GC-MS determination of eight phthalates in total and migrated portions of plasticized polymeric toys and childcare articles.

PubMed

Al-Natsheh, Mais; Alawi, Mahmoud; Fayyad, Manar; Tarawneh, Ibrahim

2015-03-15

A gas chromatography/mass spectrometric method was developed for the simultaneous determination of eight phthalic acid esters (PAEs) in toys and child care articles that are made of plasticized plastic. The novel method was used to determine the total concentration of the PAEs in addition to the migrated PAEs values into artificial saliva, under conditions that simulate real life situations. The extraction method, which was developed for the first time to determine the total concentration of PAEs, utilized a novel optimization of four parameters involving the solvent, time, temperature and weight of sample. The PAEs were extracted with tetrahydrofuran, as extraction the solvent, and using the ultrasonic water bath shaker for 30min, at room temperature. Another extraction method was developed to determine the migrated PAEs into artificial saliva at pH 6.2 and 37°C, implementing a liquid-liquid extraction with chloroform. Both methods were subjected to validation steps in terms of linearity, precision, accuracy and recovery, which ensured that all obtained results were well within the norms of acceptable limits and specifications. The analytes were separated at the following retention times: 4.99, 5.21, 5.31, 6.63, 7.41, 9.05min for di-"isobutyl" phthalate (DIBP), dibutyl phthalate (DBP), bis(2-methoxyethyl)phthalate (DMEP), benzyl butyl phthalate (BBP), dibutyl phthalate (DEHP) and di-n-octyl phthalate (DnOP), respectively. The chromatographic peaks corresponding to di-"isononyl" phthalate (DINP) and di-"isononyl" phthalate (DIDP), were separated, using the extracted ion chromatogram (EIC) mode within the time ranges of 8.05-12.10min for DINP and 8.50-14.50min for DIDP. The instrument detection limits for DIBP, DBP, DMEP, BBP, DEHP, DnOP, DINP and DIDP were determined at 0.100, 0.100, 0.045, 0.035, 0.015, 0.370, 0.320, 0.260μg/ml, respectively. The calibration curve working ranges were determined at 0.5-25μg/ml for DIBP, DBP, DMEP, BBP and DEHP, 2-100μg/ml for DnOP and 5-100μg/ml for DINP and DIDP. The coefficients of variation (precision) for the total PAEs method were in the range 0.55-12.10% and for the migration method were in the range 0.72-7.70%. Recovery values for total PAEs and for the migrated PAEs were ranged within 90.6-111.7% and 86.3-117.2%; respectively. Both developed methods were used to survey the Jordanian market, where twenty seven samples were collected and tested for plastic type, total PAEs and migrated PAEs. Seventeen of those samples were found to be polyvinyl chloride (PVC), and all of them containing total PAEs having concentrations in excess of the allowed limit of 0.1% (w/w). The rest of the samples were non-PVC and only one of them containing PAEs, but below the allowed limit. In contrast, all the migration results were found to be well within the allowed limits. It was also found that as the PAEs total concentration increase, the corresponding migrated value increase, while the opposite trend holds for in the PAEs molecular weight. Copyright © 2015 Elsevier B.V. All rights reserved.

Influence of complex interfacial rheology on the thermocapillary migration of a surfactant-laden droplet in Poiseuille flow

NASA Astrophysics Data System (ADS)

Das, Sayan; Chakraborty, Suman

2018-02-01

The effect of surface viscosity on the motion of a surfactant-laden droplet in the presence of a non-isothermal Poiseuille flow is studied, both analytically and numerically. The presence of bulk-insoluble surfactants along the droplet surface results in interfacial shear and dilatational viscosities. This, in turn, is responsible for the generation of surface-excess viscous stresses that obey the Boussinesq-Scriven constitutive law for constant values of surface shear and dilatational viscosities. The present study is primarily focused on finding out how this confluence can be used to modulate droplet dynamics in the presence of Marangoni stress induced by nonuniform distribution of surfactants and temperature along the droplet surface, by exploiting an intricate interplay of the respective forcing parameters influencing the interfacial stresses. Under the assumption of negligible fluid inertia and thermal convection, the steady-state migration velocity of a non-deformable spherical droplet, placed at the centerline of an imposed unbounded Poiseuille flow, is obtained for the limiting case when the surfactant transport along the interface is dominated by surface diffusion. Our analysis proves that the droplet migration velocity is unaffected by the shear viscosity whereas the dilatational viscosity has a significant effect on the same. The surface viscous effects always retard the migration of a surfactant-laden droplet when the temperature in the far-field increases in the direction of the imposed flow although the droplet always migrates towards the hotter region. On the contrary, if a large temperature gradient is applied in a direction opposite to that of the imposed flow, the direction of droplet migration gets reversed. However, for a sufficiently high value of dilatational surface viscosity, the direction of droplet migration reverses. For the limiting case in which the surfactant transport along the droplet surface is dominated by surface convection, on the other hand, surface viscosities do not have any effect on the motion of the droplet. These results are likely to have far-reaching consequences in designing an optimal migration path in droplet-based microfluidic technology.

Migration measurement and modelling from poly(ethylene terephthalate) (PET) into soft drinks and fruit juices in comparison with food simulants.

PubMed

Franz, R; Welle, F

2008-08-01

Poly(ethylene terephthalate) (PET) bottles are widely used for beverages. Knowledge about the migration of organic compounds from the PET bottle wall into contact media is of interest especially when post-consumer recyclates are introduced into new PET bottles. Using migration theory, the migration of a compound can be calculated if the concentration in the bottle wall is known. On the other hand, for any given specific migration limit or maximum target concentration for organic chemical compounds in the bottled foodstuffs, the maximum allowable concentrations in the polymer CP,0 can be calculated. Since a food simulant cannot exactly simulate the real migration into the foodstuff or beverages, a worse-case simulation behaviour is the intention. However, if the migration calculation should not be too overestimative, the polymer-specific kinetic parameter for migration modelling, the so-called AP value, should be established appropriately. One objective of the study was the kinetic determination of the specific migration behaviour of low molecular weight compounds such as solvents with relatively high diffusion rates and, therefore, with high migration potential from the PET bottle wall into food simulants in comparison with real beverages. For this purpose, model contaminants were introduced into the bottle wall during pre-form production. The volatile compounds toluene and chlorobenzene were established at concentrations from about 20-30 mg kg(-1) to 300-350 mg kg(-1). Phenyl cyclohexane was present at concentrations of 35, 262 and 782 mg kg(-1), respectively. The low volatile compounds benzophenone and methyl stearate have bottle wall concentrations of about 100 mg kg(-1) in the low spiking level up to about 1000 mg kg(-1) in the highly spiked test bottle. From these experimental data, the polymer specific parameters (AP values) from mathematical migration modelling were derived. The experimental determined diffusing coefficients were determined, calculated and compared with literature data and an AP' value of 1.0 was derived thereof for non-swelling food simulants like 3% acetic acid, 10% ethanol or iso-octane. For more swelling condition, e.g. 95% ethanol as food simulant, an AP' value of 3.1 seems to be suitable for migration calculation. In relation to PET recycling safety aspects, maximum concentrations in the bottle wall were established for migrants/contaminants with different molecular weights, which correspond with a migration limit of 10 microg kg(-1). From the experimental data obtained using food simulants and in comparison with beverages, the most appropriate food simulant for PET packed foods with a sufficient but not too overestimative worse-case character was found to be 50% ethanol. In addition, it can be shown that mass transport from PET is generally controlled by the very low diffusion in the polymer and, as a consequence, partitioning coefficients (KP/F values) of migrants between the polymer material and the foodstuff do not influence the migration levels significantly. An important consequence is that migration levels from PET food-contact materials are largely independent from the nature of the packed food, which on the other hand simplifies exposure estimations from PET.

Defect evolution and impurity migration in Na-implanted ZnO

NASA Astrophysics Data System (ADS)

Neuvonen, Pekka T.; Vines, Lasse; Venkatachalapathy, Vishnukanthan; Zubiaga, Asier; Tuomisto, Filip; Hallén, Anders; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

2011-11-01

Secondary ion mass spectrometry (SIMS) and positron annihilation spectroscopy (PAS) have been applied to study impurity migration and open volume defect evolution in Na+ implanted hydrothermally grown ZnO samples. In contrast to most other elements, the presence of Na tends to decrease the concentration of open volume defects upon annealing and for temperatures above 600∘C, Na exhibits trap-limited diffusion correlating with the concentration of Li. A dominating trap for the migrating Na atoms is most likely Li residing on Zn site, but a systematic analysis of the data suggests that zinc vacancies also play an important role in the trapping process.

Oxygen migration enthalpy likely limits oxide precipitate dissolution during tabula rasa

NASA Astrophysics Data System (ADS)

Looney, E. E.; Laine, H. S.; Youssef, A.; Jensen, M. A.; LaSalvia, V.; Stradins, P.; Buonassisi, T.

2017-09-01

In industrial silicon solar cells, oxygen-related defects lower device efficiencies by up to 20% (rel.). In order to mitigate these defects, a high-temperature homogenization anneal called tabula rasa (TR) that has been used in the electronics industry is now proposed for use in solar-grade wafers. This work addresses the kinetics of tabula rasa by elucidating the activation energy governing oxide precipitate dissolution, which is found to be 2.6 ± 0.5 eV. This value is consistent within uncertainty to the migration enthalpy of oxygen interstitials in silicon, implying TR to be kinetically limited by oxygen point-defect diffusion. This large activation energy is observed to limit oxygen precipitate dissolution during standard TR conditions, suggesting that more aggressive annealing conditions than conventionally used are required for complete bulk microdefect mitigation.

Oxygen migration enthalpy likely limits oxide precipitate dissolution during tabula rasa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Looney, E. E.; Laine, H. S.; Youssef, A.

In industrial silicon solar cells, oxygen-related defects lower device efficiencies by up to 20% (rel.). In order to mitigate these defects, a high-temperature homogenization anneal called tabula rasa (TR) that has been used in the electronics industry is now proposed for use in solar-grade wafers. This work addresses the kinetics of tabula rasa by elucidating the activation energy governing oxide precipitate dissolution, which is found to be 2.6 +/- 0.5 eV. This value is consistent within uncertainty to the migration enthalpy of oxygen interstitials in silicon, implying TR to be kinetically limited by oxygen point-defect diffusion. This large activation energymore » is observed to limit oxygen precipitate dissolution during standard TR conditions, suggesting that more aggressive annealing conditions than conventionally used are required for complete bulk microdefect mitigation.« less

Suicidal Ideation and Migration Aspirations among Youth in Central Mexico

PubMed Central

Hoffman, Steven

2014-01-01

Over the past 100 years the state of Guanajuato has consistently been one of the highest migrant sending states in Mexico. Youth living in high migratory states such as Guanajuato are heavily influenced by the expectation that they will travel to the US, and research has shown that those who do not migrate may be looked down upon by members of their community. This secondary analysis looks at the connection between suicidal ideation and migration aspirations among a group of adolescents living in Guanajuato, Mexico. Data were originally collected in 2007 as part of a comprehensive health survey of youth attending an alternative high schooling program. Regression analyses show that suicidal ideation predicts intentions to migrate among both males and females, while other factors differentially influence the adolescents by gender. The results indicate that suicidal ideation may be associated with migration aspirations among Mexican youth living in high migratory communities. Study limitations and implications are discussed. PMID:24373268

Forced migration and mental health: prolonged internal displacement, return migration and resilience.

PubMed

Siriwardhana, Chesmal; Stewart, Robert

2013-03-01

Forced internal displacement has been rising steadily, mainly due to conflict. Many internally displaced people (IDP) experience prolonged displacement. Global research evidence suggests that many of these IDP are at high risk for developing mental disorders, adding weight to the global burden of disease. However, individual and community resilience may act as protective factors. Return migration may be an option for some IDP populations, especially when conflicts end, although return migration may itself be associated with worse mental health. Limited evidence is available on effects of resettlement or return migration following prolonged forced internal displacement on mental health. Also, the role of resilience factors remains to be clarified following situations of prolonged displacement. The public health impact of internal displacement is not clearly understood. Epidemiological and interventional research in IDP mental health needs to look beyond medicalised models and encompass broader social and cultural aspects. The resilience factor should be integrated and explored more in mental health research among IDP and a clearly focused multidisciplinary approach is advocated.

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

NASA Astrophysics Data System (ADS)

Forsyth, C.; Watt, C. E. J.; Rae, I. J.; Fazakerley, A. N.; Kalmoni, N. M. E.; Freeman, M. P.; Boakes, P. D.; Nakamura, R.; Dandouras, I.; Kistler, L. M.; Jackman, C. M.; Coxon, J. C.; Carr, C. M.

2014-12-01

During substorm growth phases, magnetic reconnection at the magnetopause extracts ~1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase.

Problems of magnesium oxide wallboard usage in construction

NASA Astrophysics Data System (ADS)

Gravit, Marina; Zybina, Olga; Vaititckii, Artem; Kopytova, Anna

2017-10-01

Magnesium oxide wallboard is the building and finishing material, which has a reputation of new generational ecological constructing material. It has a wide range of uses: as a revetment in ventilated facades’ production, as a decorative material, as different types of formworks for a foundation filling and as a protector against a fire threat. During the study it was considered that magnesium oxide wallboards have some defects, such as moisture formation as a concentrated brine on the surface under special climatic conditions and absence of clear distinguishing between different types of magnesia boards. Usage of this material can become a cause of frame’s corrosion and origin of mold on wooden details. Authors provide the information from a foreign data source about negative consequences of SML usage. In conclusion researchers state that it is necessary to provide a clear magnesium wallboards classification and define technical requirements, which will, in their opinion, lead to Russian standard formulation.

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

PubMed Central

Forsyth, C; Watt, C E J; Rae, I J; Fazakerley, A N; Kalmoni, N M E; Freeman, M P; Boakes, P D; Nakamura, R; Dandouras, I; Kistler, L M; Jackman, C M; Coxon, J C; Carr, C M

2014-01-01

During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase. PMID:26074645

Increases in plasma sheet temperature with solar wind driving during substorm growth phases.

PubMed

Forsyth, C; Watt, C E J; Rae, I J; Fazakerley, A N; Kalmoni, N M E; Freeman, M P; Boakes, P D; Nakamura, R; Dandouras, I; Kistler, L M; Jackman, C M; Coxon, J C; Carr, C M

2014-12-28

During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼10 15  J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase.

Prime Contract Awards Alphabetically by Contractor, by State or Country, and Place, FY83, Part 1 (A & A Chemical Toilet Rentals-Benatec Associate).

DTIC Science & Technology

1983-01-01

OAH01 0869 DAAH01-83-C0397 B C A 1 2 2 1430 CMC A2 GUIDED MISSILE REMOTE CONTRO 8 A 3 5 J 01B 1 B J 1 B 40 LOCATION TOTAL 2 s8 TEC INC TEXARKANA TEXAS...3 4 5 A 1005 7 B J I F 117 LOCATION TOTAL 7 99 ARKLA INC TEXARKANA TEXAS 067380 7840 44 1 K OAS47 0018 DAAG47-75-CO060 B C Z 1 2 2 S111 000 51...79-C0002 E P A 1 2 2 J019 000 A3 MAINT-REPAIR OF EQ/SHIPS-SML 8 4 7 3 C 0000 0 J 4 L 57 2 A 88791 2017 N62791-79-C0002 D C A 1 2 2 J019 000 A3 MAINT

Prospects for the Comparative Study of International Migration using quasi-longitudinal micro-data

PubMed Central

Liu, Mao-Mei; Creighton, Mathew J.; Riosmena, Fernando; Baizán Mun͂oz, Pau

2017-01-01

BACKGROUND Longitudinal micro-level data about international migration behavior are notoriously difficult to collect, but data collection efforts have become more frequent in recent years. Comparative research of the patterns and processes of international migration, however, remains quite rare, especially that which compares across regions. OBJECTIVE We highlight the promises and difficulties of comparative international migration research, by offering a detailed comparison of two prominent data collection efforts. METHODS We systematically review existing sources of longitudinal and quasi-longitudinal individual-level and household-level data of international migration. We then compare two widely-used data sources: the Mexican Migration Project (MMP) and the Migration between Africa and Europe project (MAFE). RESULTS Data collection efforts are increasingly diverse, yet public accessibility of data remains limited. Also, comparability of data collected across settings can be complicated. In our MMP-MAFE analysis, we show some ways in which comparability can be achieved. CONCLUSIONS A primary roadblock to international comparative research is that, with some exceptions, the public accessibility of data remains low. Even when data is public and surveys are modeled after one another, comparability is not easy due to necessary trade-offs in adapting surveys to local settings and to developments in the field. CONTRIBUTION We demonstrate that, despite great strides in collecting quasi-longitudinal data of international migration, data accessibility still hinders the study of migration. With regards to comparability, our article provides important lessons for future data collection and analysis efforts that could improve comparability and thus advance understanding of the complex dynamics of international migration. PMID:29276429

Emergence of long distance bird migrations: a new model integrating global climate changes

NASA Astrophysics Data System (ADS)

Louchart, Antoine

2008-12-01

During modern birds history, climatic and environmental conditions have evolved on wide scales. In a continuously changing world, landbirds annual migrations emerged and developed. However, models accounting for the origins of these avian migrations were formulated with static ecogeographic perspectives. Here I reviewed Cenozoic paleoclimatic and paleontological data relative to the palearctic paleotropical long distance (LD) migration system. This led to propose a new model for the origin of LD migrations, the ‘shifting home’ model (SHM). It is based on a dynamic perspective of climate evolution and may apply to the origins of most modern migrations. Non-migrant tropical African bird taxa were present at European latitudes during most of the Cenozoic. Their distribution limits shifted progressively toward modern tropical latitudes during periods of global cooling and increasing seasonality. In parallel, decreasing winter temperatures in the western Palearctic drove shifts of population winter ranges toward the equator. I propose that this induced the emergence of most short distance migrations, and in turn LD migrations. This model reconciliates ecologically tropical ancestry of most LD migrants with predominant winter range shifts, in accordance with requirements for heritable homing. In addition, it is more parsimonious than other non-exclusive models. Greater intrinsic plasticity of winter ranges implied by the SHM is supported by recently observed impacts of the present global warming on migrating birds. This may induce particular threats to some LD migrants. The ancestral, breeding homes of LD migrants were not ‘northern’ or ‘southern’ but shifted across high and middle latitudes while migrations emerged through winter range shifts themselves.

Migration kinetics of mineral oil hydrocarbons from recycled paperboard to dry food: monitoring of two real cases.

PubMed

Lorenzini, R; Biedermann, M; Grob, K; Garbini, D; Barbanera, M; Braschi, I

2013-01-01

Mineral oil hydrocarbons present in printing inks and recycled paper migrate from paper-based food packaging to foods primarily through the gas phase. Migration from two commercial products packed in recycled paperboard, i.e. muesli and egg pasta, was monitored up to the end of their shelf life (1 year) to study the influence of time, storage conditions, food packaging structure and temperature. Mineral oil saturated and aromatic hydrocarbons (MOSH and MOAH, respectively), and diisopropyl naphthalenes (DIPN) were monitored using online HPLC-GC/FID. Storage conditions were: free standing, shelved, and packed in transport boxes of corrugated board, to represent domestic, supermarket and warehouse storage, respectively. Migration to food whose packs were kept in transport boxes was the highest, especially after prolonged storage, followed by shelved and free-standing packs. Tested temperatures were representative of refrigeration, room temperature, storage in summer months and accelerated migration testing. Migration was strongly influenced by temperature: for egg pasta directly packed in paperboard, around 30 mg kg⁻¹ of MOSH migrated in 8 months at 20°C, but in only 1 week at 40°C. Muesli was contained into an internal polyethylene bag, which firstly adsorbed hydrocarbons and later released them partly towards the food. Differently, the external polypropylene bag, containing pasta and recycled paper tray, strongly limited the migration towards the atmosphere and gave rise to the highest level of food contamination. Tests at increased temperatures not only accelerated migration, but also widened the migration of hydrocarbons to higher molecular masses, highlighting thus a difficult interpretation of data from accelerated simulation.

Application of Geographic Information System (GIS) to Model the Hydrocarbon Migration: Case Study from North-East Malay Basin, Malaysia

NASA Astrophysics Data System (ADS)

Rudini; Nasir Matori, Abd; Talib, Jasmi Ab; Balogun, Abdul-Lateef

2018-03-01

The purpose of this study is to model the migration of hydrocarbon using Geographic Information System (GIS). Understanding hydrocarbon migration is important since it can mean the difference between success and failure in oil and gas exploration project. The hydrocarbon migration modeling using geophysical method is still not accurate due to the limitations of available data. In recent years, GIS has emerged as a powerful tool for subsurface mapping and analysis. Recent studies have been carried out about the abilities of GIS to model hydrocarbon migration. Recent advances in GIS support the establishment and monitoring of prediction hydrocarbon migration. The concept, model, and calculation are based on the current geological situation. The spatial data of hydrocarbon reservoirs is determined by its geometry of lithology and geophysical attributes. Top of Group E horizon of north-east Malay basin was selected as the study area due to the occurrence of hydrocarbon migration. Spatial data and attributes data such as seismic data, wells log data and lithology were acquired and processed. Digital Elevation Model (DEM) was constructed from the selected horizon as a result of seismic interpretation using the Petrel software. Furthermore, DEM was processed in ArcGIS as a base map to shown hydrocarbon migration in north-east Malay Basin. Finally, all the data layers were overlaid to produce a map of hydrocarbon migration. A good data was imported to verify the model is correct.

Feasibility study on the use of probabilistic migration modeling in support of exposure assessment from food contact materials.

PubMed

Poças, Maria F; Oliveira, Jorge C; Brandsch, Rainer; Hogg, Timothy

2010-07-01

The use of probabilistic approaches in exposure assessments of contaminants migrating from food packages is of increasing interest but the lack of concentration or migration data is often referred as a limitation. Data accounting for the variability and uncertainty that can be expected in migration, for example, due to heterogeneity in the packaging system, variation of the temperature along the distribution chain, and different time of consumption of each individual package, are required for probabilistic analysis. The objective of this work was to characterize quantitatively the uncertainty and variability in estimates of migration. A Monte Carlo simulation was applied to a typical solution of the Fick's law with given variability in the input parameters. The analysis was performed based on experimental data of a model system (migration of Irgafos 168 from polyethylene into isooctane) and illustrates how important sources of variability and uncertainty can be identified in order to refine analyses. For long migration times and controlled conditions of temperature the affinity of the migrant to the food can be the major factor determining the variability in the migration values (more than 70% of variance). In situations where both the time of consumption and temperature can vary, these factors can be responsible, respectively, for more than 60% and 20% of the variance in the migration estimates. The approach presented can be used with databases from consumption surveys to yield a true probabilistic estimate of exposure.

An overview of some concepts, potentials, issues, and realities of assisted migration for climate change adaptation in forests

Treesearch

Louis R. Iverson; Matthew P. Peters; Stephen Matthews; Anantha Prasad

2013-01-01

The climate has always been changing, but the rapid rate of climate change, as projected by the IPCC (2007) will likely place unique stresses on plant communities. In addition, anthropogenic barriers (e.g., fragmented land use) present a significant modern constraint that will limit the ability of species migration in responses to a changing climate. As such, managers...

Endoscopic suture fixation is associated with reduced migration of esophageal fully covered self-expandable metal stents (FCSEMS).

PubMed

Wright, Andrew; Chang, Andrew; Bedi, Aarti Oza; Wamsteker, Erik-Jan; Elta, Grace; Kwon, Richard S; Carrott, Phillip; Elmunzer, B Joseph; Law, Ryan

2017-09-01

Esophageal fully covered self-expandable metal stents (FCSEMS) are indicated for the management of benign and malignant conditions of the esophagus including perforations, leaks, and strictures. FCSEMS are resistant to tissue ingrowth and are removable; however, stent migration occurs in 30-55% of cases. Endoscopic suture fixation of FCSEMS has been utilized to decrease the risk of stent migration though data supporting this practice remain limited. The primary aim of this study was to compare clinical outcomes and migration rate of patients who underwent placement of esophageal FCSEMS with and without endoscopic suture fixation. Our single-center, retrospective, cohort study includes patients who underwent esophageal FCSEMS placement with and without endoscopic suture fixation between January 1, 2012, and November 11, 2015. Baseline patient characteristics, procedural details, and clinical outcomes were abstracted. Logistic regression was performed to identify clinical and technical factors associated with outcomes and stent migration. A total of 51 patients underwent 62 FCSEMS placements, including 21 procedures with endoscopic suture fixation and 41 without. Suture fixation was associated with reduced risk of stent migration (OR 0.13, 95% CI 0.03-0.47). Prior stent migration was associated with significantly higher risk of subsequent migration (OR 6.4, 95% CI 1.6-26.0). Stent migration was associated with lower likelihood of clinical success (OR 0.21, 95% CI 0.06-0.69). There was a trend toward higher clinical success among patients undergoing suture fixation (85.7 vs. 60.9%, p = 0.07). Endoscopic suture fixation of FCSEMS was associated with a reduced stent migration rate. Appropriate patient selection for suture fixation of FCSEMS may lead to reduced migration in high-risk patients.

MiR-9-5p promotes MSC migration by activating β-catenin signaling pathway.

PubMed

Li, Xianyang; He, Lihong; Yue, Qing; Lu, Junhou; Kang, Naixin; Xu, Xiaojing; Wang, Huihui; Zhang, Huanxiang

2017-07-01

Mesenchymal stem cells (MSCs) have the potential to treat various tissue damages, but the very limited number of cells that migrate to the damaged region strongly restricts their therapeutic applications. Full understanding of mechanisms regulating MSC migration will help to improve their migration ability and therapeutic effects. Increasing evidence shows that microRNAs play important roles in the regulation of MSC migration. In the present study, we reported that miR-9-5p was upregulated in hepatocyte growth factor -treated MSCs and in MSCs with high migration ability. Overexpression of miR-9-5p promoted MSC migration, whereas inhibition of endogenous miR-9-5p decreased MSC migration. To elucidate the underlying mechanism, we screened the target genes of miR-9-5p and report for the first time that CK1α and GSK3β, two inhibitors of β-catenin signaling pathway, were direct targets of miR-9-5p in MSCs and that overexpression of miR-9-5p upregulated β-catenin signaling pathway. In line with these data, inhibition of β-catenin signaling pathway by FH535 decreased the miR-9-5p-promoted migration of MSCs, while activation of β-catenin signaling pathway by LiCl rescued the impaired migration of MSCs triggered by miR-9-5p inhibitor. Furthermore, the formation and distribution of focal adhesions as well as the reorganization of F-actin were affected by the expression of miR-9-5p. Collectively, these results demonstrate that miR-9-5p promotes MSC migration by upregulating β-catenin signaling pathway, shedding light on the optimization of MSCs for cell replacement therapy through manipulating the expression level of miR-9-5p. Copyright © 2017 the American Physiological Society.

Refugee children's play: Before and after migration to Australia.

PubMed

MacMillan, Kelli K; Ohan, Jeneva; Cherian, Sarah; Mutch, Raewyn C

2015-08-01

Play is vital to children's development, health and resilience. Play modulates cognitive, emotional and social well-being. Children constitute approximately half of all humanitarian refugee entrants resettled in Australia. Refugee children are commonly victims and witnesses of war and persecution, living across resource-poor environs during transit. Little is known about the effects of refugee migration on play. This study explores how refugee children engaged in play pre-migration (in their home country) and post-migration (Australia). Refugee children attending the Refugee Health Clinic of a tertiary children's hospital were invited to complete a qualitative descriptive study of play. The children were asked to draw how they played pre- and post-migration. Drawings were analysed for (i) the presence of play; (ii) location of play; and (iii) drawing detail. Nineteen refugee children were recruited (mean age 8.5 years ± standard deviation 6.4 months). Significantly fewer children drew play pre- versus post-migration (11/19, 58% vs. 18/19, 95% P < 0.03). Girls had greater comparative changes in play with migration (pre: 2/8, 25% vs. post: 7/8, 87%, P = 0.06), trending to significance. Of those children who drew play, almost all drew playing outside (pre-migration: 10/11, 90.9%; post-migration: 17/18, 94.4%). Drawings showed equivalent detail pre- and post-migration. Resettled refugee children, especially girls, demonstrated limited play pre-migration, with higher levels of engagement post-resettlement. Facilitating opportunities for variety of play may strengthen positive resettlement outcomes for children and parents. Larger longitudinal studies examining play in refugee children and associations with physical, development and psychological well-being are warranted. © 2015 The Authors. Journal of Paediatrics and Child Health © 2015 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Ontogenetic behavior and migration of Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus, and shortnose sturgeon, A. brevirostrum, with notes on social behavior

USGS Publications Warehouse

Kynard, B.; Horgan, M.

2002-01-01

Ontogenetic behavior of Hudson River Atlantic sturgeon and Connecticut River shortnose sturgeon early life intervals were similar during laboratory observations. After hatching, free embryos were photonegative and sought cover. When embryos developed into larvae, fish left cover, were photopositive, and initiated downstream migration. Free embryos may remain at the spawning site instead of migrating downstream because the risk of predation at spawning sites is low. The two species are sympatric, but not closely related, so the similarities in innate behaviors suggest common adaptations, not phylogenetlc relationship. Atlantic sturgeon migrated downstream for 12 days (peak, first 6 days), shortnose sturgeon migrated for 3 days, and year-0 juveniles of both species did not resume downstream migration. Short or long migrations of larvae may reflect different styles related to the total migratory distance from spawning sites to juvenile rearing areas. Atlantic sturgeon need to move a short distance to reach rearing areas and they had a long 1-step migration of 6-12 days. In contrast, shortnose sturgeon need to move a long distance to reach all rearing areas. This may be accomplished by a 2-step migration, of which the brief migration of larvae is only the first step. Early migrant Atlantic sturgeon were nocturnal, while late migrants were diurnal, and shortnose sturgeon were diurnal. These diel differences may also be adaptations for long (Atlantic sturgeon) or short (shortnose sturgeon) migrations. Cultured shortnose sturgeon, and possibly Atlantic sturgeon, have a dominance hierarchy with large fish dominant when competing for limited foraging space. Social behavior may be more important in the life history of wild sturgeons than is generally recognized.

ProBDNF inhibits collective migration and chemotaxis of rat Schwann cells.

PubMed

Ding, You-Quan; Li, Xuan-Yang; Xia, Guan-Nan; Ren, Hong-Yi; Zhou, Xin-Fu; Su, Bing-Yin; Qi, Jian-Guo

2016-10-01

Schwann cell migration, including collective migration and chemotaxis, is essential for the formation of coordinate interactions between Schwann cells and axons during peripheral nerve development and regeneration. Moreover, limited migration of Schwann cells imposed a serious obstacle on Schwann cell-astrocytes intermingling and spinal cord repair after Schwann cell transplantation into injured spinal cords. Recent studies have shown that mature brain-derived neurotrophic factor, a member of the neurotrophin family, inhibits Schwann cell migration. The precursor form of brain-derived neurotrophic factor, proBDNF, was expressed in the developing or degenerating peripheral nerves and the injured spinal cords. Since "the yin and yang of neurotrophin action" has been established as a common sense, proBDNF would be expected to promote Schwann cell migration. However, we found, in the present study, that exogenous proBDNF also inhibited in vitro collective migration and chemotaxis of RSC 96 cells, a spontaneously immortalized rat Schwann cell line. Moreover, proBDNF suppressed adhesion and spreading of those cells. At molecular level, proBDNF inhibits F-actin polymerization and focal adhesion dynamics in cultured RSC 96 cells. Therefore, our results suggested a special case against the classical opinion of "the yin and yang of neurotrophin action" and implied that proBDNF might modulate peripheral nerve development or regeneration and spinal cord repair through perturbing native or transplanted Schwann cell migration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cyclic migration of weak earthquakes between Lunigiana earthquake of October 10, 1995 and Reggio Emilia earthquake of October 15, 1996 (Northern Italy)

NASA Astrophysics Data System (ADS)

di Giovambattista, R.; Tyupkin, Yu

The cyclic migration of weak earthquakes (M 2.2) which occurred during the yearprior to the October 15, 1996 (M = 4.9) Reggio Emilia earthquake isdiscussed in this paper. The onset of this migration was associated with theoccurrence of the October 10, 1995 (M = 4.8) Lunigiana earthquakeabout 90 km southwest from the epicenter of the Reggio Emiliaearthquake. At least three series of earthquakes migrating from theepicentral area of the Lunigiana earthquake in the northeast direction wereobserved. The migration of earthquakes of the first series terminated at adistance of about 30 km from the epicenter of the Reggio Emiliaearthquake. The earthquake migration of the other two series halted atabout 10 km from the Reggio Emilia epicenter. The average rate ofearthquake migration was about 200-300 km/year, while the time ofrecurrence of the observed cycles varied from 68 to 178 days. Weakearthquakes migrated along the transversal fault zones and sometimesjumped from one fault to another. A correlation between the migratingearthquakes and tidal variations is analysed. We discuss the hypothesis thatthe analyzed area is in a state of stress approaching the limit of thelong-term durability of crustal rocks and that the observed cyclic migrationis a result of a combination of a more or less regular evolution of tectonicand tidal variations.

Age at migration and self-rated health trajectories after age 50: understanding the older immigrant health paradox.

PubMed

Gubernskaya, Zoya

2015-03-01

This research contributes to the "immigrant health paradox" debate by testing the hypothesis that older age at migration is associated with the increased risk of poor health in later life. Using the 1992-2008 Health and Retirement Study, I construct linear random-intercept models to estimate self-rated health (SRH) trajectories after age 50 for the native and foreign born by age at migration. At age 50, both Hispanic and non-Hispanic foreign born report better SRH compared with their native-born counterparts, net of race, gender, and education. Non-Hispanic foreign born who migrated after age 35 and Hispanic foreign born who migrated after age 18, however, experience steeper decline in SRH after age 50, which results in a health disadvantage vis-à-vis the native born in old age. Education has a smaller protective effect on SRH for the foreign born, especially those who migrated as adults. Age at migration is an important factor for understanding health status of older immigrants. Steeper health decline in later life of the foreign born who migrated in advanced ages may be related to longer exposure to unfavorable conditions in home countries and limited opportunities for incorporation in the United States. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Nurses on the move: a global overview.

PubMed

Kingma, Mireille

2007-06-01

To look at nurse migration flows in the light of national nursing workforce imbalances, examine factors that encourage or inhibit nurse mobility, and explore the potential benefits of circular migration. The number of international migrants has doubled since 1970 and nurses are increasingly part of the migratory stream. Critical nursing shortages in industrialized countries are generating a demand that is fueling energetic international recruitment campaigns. Structural adjustments in the developing countries have created severe workforce imbalances and shortfalls often coexist with large numbers of unemployed health professionals. A nurse's motivation to migrate is multifactorial, not limited to financial incentives, and barriers exist that discourage or slow the migration process. The migration flows vary in direction and magnitude over time, responding to socioeconomic factors present in source and destination countries. The dearth of data on which to develop international health human resource policy remains. There is growing recognition, however, that migration will continue and that temporary migration will be a focus of attention in the years to come. Today's search for labor is a highly organized global hunt for talent that includes nurses. International migration is a symptom of the larger systemic problems that make nurses leave their jobs. Nurse mobility becomes a major issue only in a context of migrant exploitation or nursing shortage. Injecting migrant nurses into dysfunctional health systems-ones that are not capable of attracting and retaining staff domestically-will not solve the nursing shortage.

Tumor cell migration screen identifies SRPK1 as breast cancer metastasis determinant.

PubMed

van Roosmalen, Wies; Le Dévédec, Sylvia E; Golani, Ofra; Smid, Marcel; Pulyakhina, Irina; Timmermans, Annemieke M; Look, Maxime P; Zi, Di; Pont, Chantal; de Graauw, Marjo; Naffar-Abu-Amara, Suha; Kirsanova, Catherine; Rustici, Gabriella; Hoen, Peter A C 't; Martens, John W M; Foekens, John A; Geiger, Benjamin; van de Water, Bob

2015-04-01

Tumor cell migration is a key process for cancer cell dissemination and metastasis that is controlled by signal-mediated cytoskeletal and cell matrix adhesion remodeling. Using a phagokinetic track assay with migratory H1299 cells, we performed an siRNA screen of almost 1,500 genes encoding kinases/phosphatases and adhesome- and migration-related proteins to identify genes that affect tumor cell migration speed and persistence. Thirty candidate genes that altered cell migration were validated in live tumor cell migration assays. Eight were associated with metastasis-free survival in breast cancer patients, with integrin β3-binding protein (ITGB3BP), MAP3K8, NIMA-related kinase (NEK2), and SHC-transforming protein 1 (SHC1) being the most predictive. Examination of genes that modulate migration indicated that SRPK1, encoding the splicing factor kinase SRSF protein kinase 1, is relevant to breast cancer outcomes, as it was highly expressed in basal breast cancer. Furthermore, high SRPK1 expression correlated with poor breast cancer disease outcome and preferential metastasis to the lungs and brain. In 2 independent murine models of breast tumor metastasis, stable shRNA-based SRPK1 knockdown suppressed metastasis to distant organs, including lung, liver, and spleen, and inhibited focal adhesion reorganization. Our study provides comprehensive information on the molecular determinants of tumor cell migration and suggests that SRPK1 has potential as a drug target for limiting breast cancer metastasis.

The Relationship Between Post-Migration Stress and Psychological Disorders in Refugees and Asylum Seekers.

PubMed

Li, Susan S Y; Liddell, Belinda J; Nickerson, Angela

2016-09-01

Refugees demonstrate high rates of post-traumatic stress disorder (PTSD) and other psychological disorders. The recent increase in forcible displacement internationally necessitates the understanding of factors associated with refugee mental health. While pre-migration trauma is recognized as a key predictor of mental health outcomes in refugees and asylum seekers, research has increasingly focused on the psychological effects of post-migration stressors in the settlement environment. This article reviews the research evidence linking post-migration factors and mental health outcomes in refugees and asylum seekers. Findings indicate that socioeconomic, social, and interpersonal factors, as well as factors relating to the asylum process and immigration policy affect the psychological functioning of refugees. Limitations of the existing literature and future directions for research are discussed, along with implications for treatment and policy.

Electrical Guidance of Human Stem Cells in the Rat Brain.

PubMed

Feng, Jun-Feng; Liu, Jing; Zhang, Lei; Jiang, Ji-Yao; Russell, Michael; Lyeth, Bruce G; Nolta, Jan A; Zhao, Min

2017-07-11

Limited migration of neural stem cells in adult brain is a roadblock for the use of stem cell therapies to treat brain diseases and injuries. Here, we report a strategy that mobilizes and guides migration of stem cells in the brain in vivo. We developed a safe stimulation paradigm to deliver directional currents in the brain. Tracking cells expressing GFP demonstrated electrical mobilization and guidance of migration of human neural stem cells, even against co-existing intrinsic cues in the rostral migration stream. Transplanted cells were observed at 3 weeks and 4 months after stimulation in areas guided by the stimulation currents, and with indications of differentiation. Electrical stimulation thus may provide a potential approach to facilitate brain stem cell therapies. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Are populations of neotropical migrant birds limited in summer or winter? implications for management

Treesearch

Thomas W. Sherry; Richard T. Holmes

1993-01-01

Understanding where in their annual cycle Neotropical-Nearctic migrant bird populations are limited is essential for developing effective management and conservation policies. A review of currently available information indicates that these long-distance migrant species may be limited by events and circumstances in both summer and winter, and possibly on migration as...

Effect of several variables in the polymer toys additive migration to saliva.

PubMed

Noguerol-Cal, R; López-Vilariño, J M; González-Rodríguez, M V; Barral-Losada, L

2011-09-30

Capacity to migrate of a representative group of polymeric additives, dyes, antioxidants, hindered amine light stabilizers (HALS) or antistatics, from plastic toys to saliva was analyzed to protect children in their habits of sucking and biting. Most of target additives appear no-regulated in toys normative but adverse effects on human health of some of them have been demonstrated and their presence in others commercial articles normative has been included. In order to offer an effective and easy tool to perform these controls, migration tests by dynamic and static contact, followed by a preconcentration step by liquid-liquid extraction (LLE) and ultra performance liquid chromatographic analysis with ultraviolet-visible and evaporative light scattering detections (UPLC-UV/Vis-ELSD) have been optimized to evaluate the migrated amounts of the additives in saliva simulant. The detection limits of the migration methodologies were ranged from 8.68 × 10(-2) to 1.30 × 10(-3)mg migrated (L simulant)(-1). Influence of several variables on this mass transport, as time, temperature and friction, was also analyzed to achieve the most aggressive methodology to protect consumers. Migration of several studied additives, whose presence has been demonstrated in several purchased commercial toys, has been observed. Copyright © 2011 Elsevier B.V. All rights reserved.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

PubMed Central

Lea, James S. E.; Wetherbee, Bradley M.; Queiroz, Nuno; Burnie, Neil; Aming, Choy; Sousa, Lara L.; Mucientes, Gonzalo R.; Humphries, Nicolas E.; Harvey, Guy M.; Sims, David W.; Shivji, Mahmood S.

2015-01-01

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks. PMID:26057337

HPLC study of migration of terephthalic acid and isophthalic acid from PET bottles into edible oils.

PubMed

Khaneghah, Amin Mousavi; Limbo, Sara; Shoeibi, Shahram; Mazinani, Somayeh

2014-08-01

Polyethylene terephthalate (PET) containers for food oil packaging were evaluated with a newly established determination method for terephthalic acid (TPA) and isophthalic acid (IPA). The analysis of monomers, TPA and IPA that migrate from PET bottles into oils was performed using high-pressure liquid chromatography with a diode array detector. Three types of commercial oils (sunflower oil, canola oil and blended oil which included sunflower oil, soy bean oil and cottonseed oil) were bottled in PET containers. These samples were incubated for 10 days at 49 °C as accelerated test condition. The means of recovery for this method varied from 70% to 72% and from 101% to 111% for TPA and IPA, respectively. The results showed that the amounts of specific migration of TPA and IPA into the samples conform to European Union legislation that identifies specific migration limits. More important, the results highlighted a different behavior of migration as a function of the fatty acid profile. Previous investigations have been performed with food simulants such as HB307 or 20% ethanol but our study used real food samples and determined trace amounts of the migrated compounds. Further investigation will be needed to better explain the influence of fatty acid conformation on migration of PET monomers. © 2013 Society of Chemical Industry.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems.

PubMed

Lea, James S E; Wetherbee, Bradley M; Queiroz, Nuno; Burnie, Neil; Aming, Choy; Sousa, Lara L; Mucientes, Gonzalo R; Humphries, Nicolas E; Harvey, Guy M; Sims, David W; Shivji, Mahmood S

2015-06-09

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

Repeated, long-distance migrations by a philopatric predator targeting highly contrasting ecosystems

NASA Astrophysics Data System (ADS)

Lea, James S. E.; Wetherbee, Bradley M.; Queiroz, Nuno; Burnie, Neil; Aming, Choy; Sousa, Lara L.; Mucientes, Gonzalo R.; Humphries, Nicolas E.; Harvey, Guy M.; Sims, David W.; Shivji, Mahmood S.

2015-06-01

Long-distance movements of animals are an important driver of population spatial dynamics and determine the extent of overlap with area-focused human activities, such as fishing. Despite global concerns of declining shark populations, a major limitation in assessments of population trends or spatial management options is the lack of information on their long-term migratory behaviour. For a large marine predator, the tiger shark Galeocerdo cuvier, we show from individuals satellite-tracked for multiple years (up to 1101 days) that adult males undertake annually repeated, round-trip migrations of over 7,500 km in the northwest Atlantic. Notably, these migrations occurred between the highly disparate ecosystems of Caribbean coral reef regions in winter and high latitude oceanic areas in summer, with strong, repeated philopatry to specific overwintering insular habitat. Partial migration also occurred, with smaller, immature individuals displaying reduced migration propensity. Foraging may be a putative motivation for these oceanic migrations, with summer behaviour showing higher path tortuosity at the oceanic range extremes. The predictable migratory patterns and use of highly divergent ecosystems shown by male tiger sharks appear broadly similar to migrations seen in birds, reptiles and mammals, and highlight opportunities for dynamic spatial management and conservation measures of highly mobile sharks.

Development of a primary diffusion source of organic vapors for gas analyzer calibration

NASA Astrophysics Data System (ADS)

Lecuna, M.; Demichelis, A.; Sassi, G.; Sassi, M. P.

2018-03-01

The generation of reference mixtures of volatile organic compounds (VOCs) at trace levels (10 ppt-10 ppb) is a challenge for both environmental and clinical measurements. The calibration of gas analyzers for trace VOC measurements requires a stable and accurate source of the compound of interest. The dynamic preparation of gas mixtures by diffusion is a suitable method for fulfilling these requirements. The estimation of the uncertainty of the molar fraction of the VOC in the mixture is a key step in the metrological characterization of a dynamic generator. The performance of a dynamic generator was monitored over a wide range of operating conditions. The generation system was simulated by a model developed with computational fluid dynamics and validated against experimental data. The vapor pressure of the VOC was found to be one of the main contributors to the uncertainty of the diffusion rate and its influence at 10-70 kPa was analyzed and discussed. The air buoyancy effect and perturbations due to the weighing duration were studied. The gas carrier flow rate and the amount of liquid in the vial were found to play a role in limiting the diffusion rate. The results of sensitivity analyses were reported through an uncertainty budget for the diffusion rate. The roles of each influence quantity were discussed. A set of criteria to minimize the uncertainty contribution to the primary diffusion source (25 µg min-1) were estimated: carrier gas flow rate higher than 37.7 sml min-1, a maximum VOC liquid mass decrease in the vial of 4.8 g, a minimum residual mass of 1 g and vial weighing times of 1-3 min. With this procedure a limit uncertainty of 0.5% in the diffusion rate can be obtained for VOC mixtures at trace levels (10 ppt-10 ppb), making the developed diffusion vials a primary diffusion source with potential to become a new reference material for trace VOC analysis.

3D printing of biomimetic microstructures for cancer cell migration.

PubMed

Huang, Tina Qing; Qu, Xin; Liu, Justin; Chen, Shaochen

2014-02-01

To understand the physical behavior and migration of cancer cells, a 3D in vitro micro-chip in hydrogel was created using 3D projection printing. The micro-chip has a honeycomb branched structure, aiming to mimic 3D vascular morphology to test, monitor, and analyze differences in the behavior of cancer cells (i.e. HeLa) vs. non-cancerous cell lines (i.e. 10 T1/2). The 3D Projection Printing system can fabricate complex structures in seconds from user-created designs. The fabricated microstructures have three different channel widths of 25, 45, and 120 microns wide to reflect a range of blood vessel diameters. HeLa and 10 T1/2 cells seeded within the micro-chip were then analyzed for morphology and cell migration speed. 10 T1/2 cells exhibited greater changes in morphology due to channel size width than HeLa cells; however, channel width had a limited effect on 10 T1/2 cell migration while HeLa cancer cell migration increased as channel width decreased. This physiologically relevant 3D cancer tissue model has the potential to be a powerful tool for future drug discoveries and cancer migration studies.

Structure and agency in development-induced forced migration: the case of Brazil’s Belo Monte Dam

PubMed Central

2017-01-01

This paper examines how structure and agency interact to shape forced migration outcomes. Specifically, I ask how structural factors such as compensation policies as well as social, financial, and human capital may either foster or constrain migration aspirations and capabilities. I use longitudinal, semi-structured interview data to study forced migration among farmers displaced by the Belo Monte Dam in the Brazilian Amazon. Results from baseline interviews indicate that nearly all community members aspired to purchase rural land in the region and maintain livelihoods as cacao farmers or cattle ranchers. Constraints limiting the ability to attain aspirations included strict requirements on land titles for properties, delays in receiving compensation, rising land prices, and the lack of power to negotiate for better compensation. Despite these constraints, most migrants succeeded in attaining aspirations, as they were able to mobilize resources such as social networks, financial capital, skills, and knowledge. These findings highlight the importance of considering the relationship between structure and agency within forced migration research. I conclude by discussing how the findings may inform resettlement policies for future cases of development- or environment-induced forced migration. PMID:28298745

Testing nano-silver food packaging to evaluate silver migration and food spoilage bacteria on chicken meat.

PubMed

Gallocchio, Federica; Cibin, Veronica; Biancotto, Giancarlo; Roccato, Anna; Muzzolon, Orietta; Carmen, Losasso; Simone, Belluco; Manodori, Laura; Fabrizi, Alberto; Patuzzi, Ilaria; Ricci, Antonia

2016-06-01

Migration of nanomaterials from food containers into food is a matter of concern because of the potential risk for exposed consumers. The aims of this study were to evaluate silver migration from a commercially available food packaging containing silver nanoparticles into a real food matrix (chicken meat) under plausible domestic storage conditions and to test the contribution of such packaging to limit food spoilage bacteria proliferation. Chemical analysis revealed the absence of silver in chicken meatballs under the experimental conditions in compliance with current European Union legislation, which establishes a maximum level of 0.010 mg kg(-1) for the migration of non-authorised substances through a functional barrier (Commission Regulation (EU) No. 10/2011). On the other hand, microbiological tests (total microbial count, Pseudomonas spp. and Enterobacteriaceae) showed no relevant difference in the tested bacteria levels between meatballs stored in silver-nanoparticle plastic bags or control bags. This study shows the importance of testing food packaging not only to verify potential silver migration as an indicator of potential nanoparticle migration, but also to evaluate the benefits in terms of food preservation so as to avoid unjustified usage of silver nanoparticles and possible negative impacts on the environment.

Reverse transendothelial cell migration in inflammation: to help or to hinder?

PubMed

Burn, Thomas; Alvarez, Jorge Ivan

2017-05-01

The endothelium provides a strong barrier separating circulating blood from tissue. It also provides a significant challenge for immune cells in the bloodstream to access potential sites of infection. To mount an effective immune response, leukocytes traverse the endothelial layer in a process known as transendothelial migration. Decades of work have allowed dissection of the mechanisms through which immune cells gain access into peripheral tissues, and subsequently to inflammatory foci. However, an often under-appreciated or potentially ignored question is whether transmigrated leukocytes can leave these inflammatory sites, and perhaps even return across the endothelium and re-enter circulation. Although evidence has existed to support "reverse" transendothelial migration for a number of years, it is only recently that mechanisms associated with this process have been described. Here we review the evidence that supports both reverse transendothelial migration and reverse interstitial migration within tissues, with particular emphasis on some of the more recent studies that finally hint at potential mechanisms. Additionally, we postulate the biological significance of retrograde migration, and whether it serves as an additional mechanism to limit pathology, or provides a basis for the dissemination of systemic inflammation.

Pressure and temperature interactions on aerobic metabolism in migrating silver eels: results in vitro.

PubMed

Scaion, D; Vettier, A; Sébert, P

2008-01-01

The European eel (Anguilla anguilla) migrates (6000 km) from European coast towards the supposed spawning area: the Sargasso Sea. This intensive and sustained swimming activity is performed without feeding and by using essentially red muscle i.e. aerobic metabolism. Temperature and hydrostatic pressure vary during migration and have known effects on energy metabolism, mainly on mitochondrial functioning. We raise the question about the existence of a pressure-temperature combination that optimizes energy metabolism. We have measured the maximal oxygen consumption (MO2) of red muscle fibres of silver eel (migrating stage) in a temperature range (5 to 25 degrees C) covering what can be reasonably expected during the migration. We have combined (random order) three temperatures (5, 15, 25 degrees C) with 5 different pressures steps from 0.1 to 10.1 MPa (corresponding to depths from surface to 1000 m). The results show that when an adequate temperature is chosen as a reference, pressure effects and pressure sensitivity depend on the temperature. Based on the fact that energy budget is limited in migrating eels, we consider that the best conditions are low temperature and high pressure.

Migration, violence, and safety among migrant sex workers: a qualitative study in two Guatemalan communities.

PubMed

Rocha-Jiménez, Teresita; Brouwer, Kimberly C; Silverman, Jay G; Morales-Miranda, Sonia; Goldenberg, Shira M

2016-09-01

Despite reports of high levels of violence among women migrants in Central America, limited evidence exists regarding the health and safety of migrant sex workers in Central America. This study is based on 16 months of field research (November 2012-February 2014), including ethnographic fieldwork, in-depth interviews, and focus groups conducted with 52 internal and international migrant female sex workers in Tecún Umán and Quetzaltenango, Guatemala, key transit and destination communities for both international and internal migrants. The analysis explored migration-related determinants of susceptibility to violence experienced by migrant sex workers across different phases of migration. Violence in home communities and economic considerations were key drivers of migration. Unsafe transit experiences (eg undocumented border crossings) and negative interactions with authorities in destination settings (eg extortion) contributed to migrant sex workers' susceptibility to violence, while enhanced access to information on immigration policies and greater migration and sex work experience were found to enhance agency and resilience. Findings suggest the urgent need for actions that promote migrant sex workers' safety in communities of origin, transit, and destination, and programmes aimed at preventing and addressing human rights violations within the context of migration and sex work.

Using geographic distribution of well-screen depths and hydrogeologic conditions to identify areas of concern for contaminant migration through inactive supply wells

NASA Astrophysics Data System (ADS)

Gailey, Robert M.

2018-02-01

Contaminant migration through inactive supply wells can negatively affect groundwater quality and the combined effects from groups of such wells may cause greater impacts. Because the number of wells in many basins is often large and the geographic areas involved can be vast, approaches are needed to estimate potential impacts and focus limited resources for investigation and corrective measures on the most important areas. One possibility is to evaluate the geographic distribution of well-screen depths relative to hydrogeologic conditions and assess where contaminant migration through wells may be impacting groundwater quality. This approach is demonstrated for a geographically extensive area in the southern Central Valley of California, USA. The conditions that lead to wells acting as conduits for contaminant migration are evaluated and areas where the problem likely occurs are identified. Although only a small fraction of all wells appear to act as conduits, potential impacts may be significant considering needs to control nonpoint-source pollution and improve drinking water quality for rural residents. Addressing a limited number of areas where contaminant migration rates are expected to be high may cost-effectively accomplish the most beneficial groundwater quality protection and improvement. While this work focuses on a specific region, the results indicate that impacts from groups of wells may occur in other areas with similar conditions. Analyses similar to that demonstrated here may guide efficient investigation and corrective action in such areas with benefits occurring for groundwater quality. Potential benefits may justify expenditures to develop the necessary data for performing the analyses.

Bubble dynamics in microchannels: inertial and capillary migration forces

NASA Astrophysics Data System (ADS)

Rivero-Rodriguez, Javier; Scheid, Benoit

2018-05-01

This work focuses on the dynamics of a train of unconfined bubbles flowing in microchan- nels. We investigate the transverse position of a train of bubbles, its velocity and the associated pressure drop when flowing in a microchannel depending on the internal forces due to viscosity, inertia and capillarity. Despite the small scales of the system, inertia, referred to as inertial migration force, play a crucial role in determining the transverse equilibrium position of the bubbles. Beside inertia and viscosity, other effects may also affect the transverse migration of bubbles such as the Marangoni surface stresses and the surface deformability. We look at the influence of surfactants in the limit of infinite Marangoni effect which yields rigid bubble interface. The resulting migration force may balance external body forces if present such as buoyancy, Dean or magnetic ones. This balance not only determines the transverse position of the bubbles but, consequently, the surrounding flow structure, which can be determinant for any mass/heat transfer process involved. Finally, we look at the influence of the bubble deformation on the equilibrium position and compare it to the inertial migration force at the centred position, explaining the stable or unstable character of this position accordingly. A systematic study of the influence of the parameters - such as the bubble size, uniform body force, Reynolds and capillary numbers - has been carried out using numerical simulations based on the Finite Element Method, solving the full steady Navier-Stokes equations and its asymptotic counterpart for the limits of small Reynolds and/or capillary numbers.

Runaway gas accretion and gap opening versus type I migration

NASA Astrophysics Data System (ADS)

Crida, A.; Bitsch, B.

2017-03-01

Growing planets interact with their natal protoplanetary disc, which exerts a torque onto them allowing them to migrate in the disc. Small mass planets do not affect the gas profile and migrate in the fast type-I migration. Although type-I migration can be directed outwards for planets smaller than 20 - 30M⊕ in some regions of the disc, planets above this mass should be lost into the central star long before the disc disperses. Massive planets push away material from their orbit and open a gap. They subsequently migrate in the slower, type II migration, which could save them from migrating all the way to the star. Hence, growing giant planets can be saved if and only if they can reach the gap opening mass, because this extends their migration timescale, allowing them to eventually survive at large orbits until the disc itself disperses. However, most of the previous studies only measured the torques on planets with fixed masses and orbits to determine the migration rate. Additionally, the transition between type-I and type-II migration itself is not well studied, especially when taking the growth mechanism of rapid gas accretion from the surrounding disc into account. Here we use isothermal 2D disc simulations with FARGO-2D1D to study the migration behaviour of gas accreting protoplanets in discs. We find that migrating giant planets always open gaps in the disc. We further show analytically and numerically that in the runaway gas accretion regime, the growth time-scale is comparable to the type-I migration time-scale, indicating that growing planets will reach gap opening masses before migrating all the way to the central star in type-I migration if the disc is not extremely viscous and/or thick. An accretion rate limited to the radial gas flow in the disc, in contrast, is not fast enough. When gas accretion by the planet is taken into account, the gap opening process is accelerated because the planet accretes material originating from its horseshoe region. This allows an accreting planet to transition to type-II migration before being lost even if gas fails to be provided for a rapid enough growth and the classical gap opening mass is not reached.

Exceptionally large migration length of carbon and topographically-facilitated self-limiting molecular beam epitaxial growth of graphene on hexagonal boron nitride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plaut, Annette S.; Wurstbauer, Ulrich; Wang, Sheng

We demonstrate growth of single-layer graphene (SLG) on hexagonal boron nitride (h-BN) by molecular beam epitaxy (MBE), only limited in area by the finite size of the h-BN flakes. Using atomic force microscopy and micro-Raman spectroscopy, we show that for growth over a wide range of temperatures (500 °C – 1000 °C) the deposited carbon atoms spill off the edge of the h-BN flakes. We attribute this spillage to the very high mobility of the carbon atoms on the BN basal plane, consistent with van der Waals MBE. The h-BN flakes vary in size from 30 μm to 100 μm,more » thus demonstrating that the migration length of carbon atoms on h-BN is greater than 100 μm. When sufficient carbon is supplied to compensate for this loss, which is largely due to this fast migration of the carbon atoms to and off the edges of the h-BN flake, we find that the best growth temperature for MBE SLG on h-BN is ~950 °C. Self-limiting graphene growth appears to be facilitated by topographic h-BN surface features: We have thereby grown MBE self-limited SLG on an h-BN ridge. This opens up future avenues for precisely tailored fabrication of nano- and hetero-structures on pre-patterned h-BN surfaces for device applications.« less

Decreasing mitochondrial fission diminishes vascular smooth muscle cell migration and ameliorates intimal hyperplasia

PubMed Central

Wang, Li; Yu, Tianzheng; Lee, Hakjoo; O'Brien, Dawn K.; Sesaki, Hiromi; Yoon, Yisang

2015-01-01

Aims Vascular smooth muscle cell (VSMC) migration in response to arterial wall injury is a critical process in the development of intimal hyperplasia. Cell migration is an energy-demanding process that is predicted to require mitochondrial function. Mitochondria are morphologically dynamic, undergoing continuous shape change through fission and fusion. However, the role of mitochondrial morphology in VSMC migration is not well understood. The aim of the study is to understand how mitochondrial fission contributes to VSMC migration and provides its in vivo relevance in the mouse model of intimal hyperplasia. Methods and results In primary mouse VSMCs, the chemoattractant PDGF induced mitochondrial shortening through the mitochondrial fission protein dynamin-like protein 1 (DLP1)/Drp1. Perturbation of mitochondrial fission by expressing the dominant-negative mutant DLP1-K38A or by DLP1 silencing greatly decreased PDGF-induced lamellipodia formation and VSMC migration, indicating that mitochondrial fission is an important process in VSMC migration. PDGF induced an augmentation of mitochondrial energetics as well as ROS production, both of which were found to be necessary for VSMC migration. Mechanistically, the inhibition of mitochondrial fission induced an increase of mitochondrial inner membrane proton leak in VSMCs, abrogating the PDGF-induced energetic enhancement and an ROS increase. In an in vivo model of intimal hyperplasia, transgenic mice expressing DLP1-K38A displayed markedly reduced ROS levels and neointima formation in response to femoral artery wire injury. Conclusions Mitochondrial fission is an integral process in cell migration, and controlling mitochondrial fission can limit VSMC migration and the pathological intimal hyperplasia by altering mitochondrial energetics and ROS levels. PMID:25587046

Motivations of nurses who migrate to Canada as domestic workers.

PubMed

Salami, B; Nelson, S; Hawthorne, L; Muntaner, C; McGillis Hall, L

2014-12-01

While some trained nurses migrate to destination countries to work as domestic workers, little is known about their migration motivations. This study explores the motivations of Philippine educated nurses who migrated to Canada through the Live-in Caregiver Program from 2001 to 2011 (a Canadian domestic worker programme). A single case study qualitative methodology and the transnational feminist concept of global care chains were utilized for this study. Interviews of 15 Philippine educated nurses who migrated to Canada as domestic workers were conducted in the province of Ontario, Canada, between February to October 2012. All participants had a baccalaureate degree from the Philippines. Interviews were tape recorded, transcribed verbatim and analysed using critical discourse analysis, aided by NVIVO 10 data analysis software. Findings reveal a multi-step immigration process in which nurses migrate from the Philippines to the Middle East (especially Saudi Arabia) and finally to Canada. While emigration from the Philippines is mainly economically driven, migration from the Middle East to Canada is primarily motivated by the desire for Canadian citizenship for the family. Also, perceived social status and lifestyle in Canada as compared to the Middle East motivates this group of women to migrate to Canada. The major limitation of this study is the lack of input from nursing policy makers. Gender-based familial ideologies and perspective on social status influence the migration decision of this group of nurses. Implications for nursing and health policy makers include the provision of clear pre-migration information (including on the nursing registration process) to internationally educated nurses, advocacy for stronger immigration policies to ensure the integration of internationally educated nurses and a consideration of gender in all health human resource policies. © 2014 International Council of Nurses.

Outmigration patterns in development transition of rural areas.

PubMed

Kaistha, K C

1987-01-01

Using a broadened concept of migration, which includes circulatory migration and commuting, this paper maintains that the patterns of outmigration vary a great deal when the level of development of a rural area is treated as an independent variable. This study uses a stratified conditional sample of 192 households selected from 3 areas: 53 households from a low developed (LDL) area, 56 from a medium (MDL), and 83 from a high (HDL). Data were collected by personal observation, interview, and genealogical methods at both the household and individual level. The households are divided into 3 main categories: 1) non-migrating, 2) commuting only, and 3) migrating (which is further divided into migrating within and migrating outside the boundaries of the district). Results show that 1) 37.51% of household members neither commute nor have migrated outside the village; 2) using the narrow definition of migration, only 10% of males over age 15 migrate, while including commuting in the definition increases the percentage to 40; 3) proportions of non-migrating households decrease from 58.4% for the LDL, to 35.7% for the MDL, to 25.3% for the HDL area; 4) the proportion of commuting only households increases from 26.4% for the LDL, to 35.7% to the MDL, and 55.4% for the HDL area; 5) 15.2% of households in the LDL, 28.6% in the MDL, and 19.3% in the HDL area experience a permanent change in residence; 6) as development accelerates, the overall volume of outmigration increases; 7) the flow of migration from rural to rural areas is mostly limited to the MDL area, while cityward migration increasingly occurs on both LDL and HDL areas; 8) the median age of commuters increases with rising levels of development; and 9) almost all migrants from the LDL area are employed in low prestige occupations, most from the HDL area have higher prestige jobs, and those from the MDL area have both high and low prestige jobs.

Inhibition or ablation of transglutaminase 2 impairs astrocyte migration.

PubMed

Monteagudo, Alina; Ji, Changyi; Akbar, Abdullah; Keillor, Jeffrey W; Johnson, Gail V W

2017-01-22

Astrocytes play numerous complex roles that support and facilitate the function of neurons. Further, when there is an injury to the central nervous system (CNS) they can both facilitate or ameliorate functional recovery depending on the location and severity of the injury. When a CNS injury is relatively severe a glial scar is formed, which is primarily composed of astrocytes. The glial scar can be both beneficial, by limiting inflammation, and detrimental, by preventing neuronal projections, to functional recovery. Thus, understanding the processes and proteins that regulate astrocyte migration in response to injury is still of fundamental importance. One protein that is likely involved in astrocyte migration is transglutaminase 2 (TG2); a multifunctional protein expressed ubiquitously throughout the brain. Its functions include transamidation and GTPase activity, among others, and previous studies have implicated TG2 as a regulator of migration. Therefore, we examined the role of TG2 in primary astrocyte migration subsequent to injury. Using wild type or TG2 -/- astrocytes, we manipulated the different functions and conformation of TG2 with novel irreversible inhibitors or mutant versions of the protein. Results showed that both inhibition and ablation of TG2 in primary astrocytes significantly inhibit migration. Additionally, we show that the deficiency in migration caused by deletion of TG2 can only be rescued with the native protein and not with mutants. Finally, the addition of TGFβ rescued the migration deficiency independent of TG2. Taken together, our study shows that transamidation and GTP/GDP-binding are necessary for inhibiting astrocyte migration and it is TGFβ independent. Copyright © 2016 Elsevier Inc. All rights reserved.

The limits to cumulative causation: international migration from Mexican urban areas.

PubMed

Fussell, Elizabeth; Massey, Douglas S

2004-02-01

We present theoretical arguments and empirical research to suggest that the principal mechanisms of cumulative causation do not function in large urban settings. Using data from the Mexican Migration Project, we found evidence of cumulative causation in small cities, rural towns and villages, but not in large urban areas. With event-history models, we found little positive effect of community-level social capital and a strong deterrent effect of urban labor markets on the likelihood of first and later U.S. trips for residents of urban areas in Mexico, suggesting that the social process of migration from urban areas is distinct from that in the more widely studied rural migrant-sending communities of Mexico.

Effects of international law on migration policy and practice: the uses of hypocrisy.

PubMed

Martin, D A

1989-01-01

Classical learning recognizes no role for international law in affecting migration policy and practice, but in modern times the salutary effects are increasing, although they remain modest. International law influences migration policy primarily through effective invocation of various forms of "soft law" in internal and international political forums. More limited prospects exist for beneficial changes enforced by international institutions and domestic courts. The article cautions against inflated expectations in the latter settings, however, particularly because overly ambitious claims can be counterproductive. It then offers a few predictions about near-term effects of international law, having to do with departures from a country, refugee law, and the integration of migrants into their new homelands.

Visualizing spatial population structure with estimated effective migration surfaces

PubMed Central

Petkova, Desislava; Novembre, John; Stephens, Matthew

2015-01-01

Genetic data often exhibit patterns broadly consistent with “isolation by distance” – a phenomenon where genetic similarity decays with geographic distance. In a heterogeneous habitat this may occur more quickly in some regions than others: for example, barriers to gene flow can accelerate differentiation between neighboring groups. We use the concept of “effective migration” to model the relationship between genetics and geography: in this paradigm, effective migration is low in regions where genetic similarity decays quickly. We present a method to visualize variation in effective migration across the habitat from geographically indexed genetic data. Our approach uses a population genetic model to relate effective migration rates to expected genetic dissimilarities. We illustrate its potential and limitations using simulations and data from elephant, human and A. thaliana populations. The resulting visualizations highlight important spatial features of population structure that are difficult to discern using existing methods for summarizing genetic variation. PMID:26642242

Kinship Paths To and From the New Europe: A Unified Analysis of Peruvian Adoption and Migration

PubMed Central

Leinaweaver, Jessaca B.

2013-01-01

This article compares migrants and adoptees of Peruvian origin residing in Europe by focusing on their respective movements out of and return to the sending country of Peru. First, it analyzes family-based reunifications by drawing on a framework from studies of adoption and kinship. Juxtaposing the experiences of adoptees with those of migrants reveals how migration, too, may be steeped in concerns about kin ties. Next, it analyzes returns of adult adoptees using a template modeled on migrant returns, focusing on the centrality of the notion of contribution. The article shows how migrants and adoptees contest the constraints of European nation-state definitions of kinship intended to limit migration. It is based on recent research with Peruvian migrants and adoptees in Spain, as well as longer-term research in Peru on migration and adoption. PMID:24443664

Sea level driven marsh expansion in a coupled model of marsh erosion and migration

USGS Publications Warehouse

Kirwan, Matthew L.; Walters, David C.; Reay, William G.; Carr, Joel

2016-01-01

Coastal wetlands are among the most valuable ecosystems on Earth, where ecosystem services such as flood protection depend nonlinearly on wetland size and are threatened by sea level rise and coastal development. Here we propose a simple model of marsh migration into adjacent uplands and couple it with existing models of seaward edge erosion and vertical soil accretion to explore how ecosystem connectivity influences marsh size and response to sea level rise. We find that marsh loss is nearly inevitable where topographic and anthropogenic barriers limit migration. Where unconstrained by barriers, however, rates of marsh migration are much more sensitive to accelerated sea level rise than rates of edge erosion. This behavior suggests a counterintuitive, natural tendency for marsh expansion with sea level rise and emphasizes the disparity between coastal response to climate change with and without human intervention.

Lactimidomycin, Iso-migrastatin and Related Glutarimide-containing 12-membered Macrolides are Extremely Potent Inhibitors of Cell Migration

PubMed Central

Ju, Jianhua; Rajski, Scott R.; Lim, Si-Kyu; Seo, Jeong-Woo; Peters, Noël R.; Hoffmann, F. Michael; Shen, Ben

2009-01-01

Migrastatin (1), iso-migrastatin (5) and lactimidomycin (7) are all glutarimide-containing polyketides known for their unique structures and cytotoxic activities against human cancer cell lines. Migrastatin, a strong inhibitor of tumor cell migration, has been an important lead in the development of antimetastatic agents. Yet studies of the related 12-membered macrolides iso-migrastatin, lactimidomycin and related analogs have been hampered by their limited availability. We report here the production, isolation, structural characterization and biological activities of iso-migrastatin, lactimidomycin, and 23 related congeners. Our studies showed that, as a family, the glutarimide-containing 12-membered macrolides are extremely potent cell migration inhibitors with some members displaying activity on par or superior to that of migrastatin as exemplified by compounds 5, 7, and 9–12. On the basis of these findings, the structures and activity of this family of compounds as cell migration inhibitors are discussed. PMID:19132897

Internal Migration and Sexual Initiation among Never Married Youths in Nigeria

PubMed Central

Mberu, Blessing Uchenna; White, Michael J

2013-01-01

The high rates of youth migration to urban and economic centers, in the context of persistent poverty and devastating HIV/AIDS burden, raises intricate social policy challenges in developing countries. This study examines patterns of internal migration and sexual initiation among Nigerian youths, using the 2003 Nigeria DHS data, descriptive statistics, Kaplan-Meier survival curves and discrete-time hazard regression models. Migrants generally show stronger association than non-migrants, and urban-urban migrants show the strongest independent association to early sexual initiation. These outcomes underscore that loss of social capital and exposure to sexually lenient urban environment increase youth's propensity to sexual engagement. Other significant covariates are age, gender, ethnic origin, education, independent living arrangement and formal employment. The findings highlight the inadequacy of policy perspectives that neglect complex contextual nuances across groups and the need to address limited livelihood opportunities that fuel youth migration to urban destinations. PMID:21435767

Comparing Past and Future Elevational vs. Latitudinal Migrations in Mountains of the Western U.S

NASA Astrophysics Data System (ADS)

Cole, K. L.; Ironside, K.; Cobb, N.

2009-12-01

During the early Holocene, plant species of the western United States responded to the warming post-glacial temperatures by migrating to higher elevations and to more northerly latitudes. Models of species response to warmer climates assume similar processes will occur in the future but the rates and extent of these future migrations are unknown. Hypothetically, the rates of elevational and latitudinal migrations should differ depending upon the importance of spatial distance in determining the resulting migration rate. The diverse topography of the western United States presents an ideal laboratory for comparing these past elevational vs. latitudinal species movements. Abundant fossil records allow comparisons between these rates following rapidly warming periods in the past such as occurred in the early Holocene. At that time, species often equilibrated to the new temperature regime rapidly where they were only required to migrate a short distance uphill. But the same species required many thousands of years to subsequently approach their northern latitudinal boundaries. Further, the upper limits and lower limits for a species often did not move synchronously, yielding additional information on the dynamics of response to rapid warming for that particular species. We calibrated the available temperature space for several dominant forest tree species of the mountains of the interior western U.S. and then calculated their early Holocene rates of migration relative to geographic space. Next we were able to compare these estimations to the observations of each species recent historical autecological response to disturbances. For many species their paleoecological rates of change were consistent with observations of their dynamics over the last century. A few species, such as the wind dispersed Populus tremuloides, re-populate disturbed areas so rapidly that they have no discernable migration delay. Other species, such as Pinus ponderosa, can expand rapidly at a rate approximating 250 to 500 m/year. But even at such a rapid rate, they would only be able to expand a total of 45 km by the end of this century. And, because of their maturation time, this could constitute only three generations. Lastly, many species of interior semi-arid regions, such as Pseudotsuga menziesii and Pinus edulis, expand at rates of less than 100 m/yr. Finally, we applied calculated migration rates to modeled areas of future potential climate for each species. We generated these areas of future potential distribution using a selection of AR4 GCMs that were applied to species-specific climate models developed from late Twentieth Century correlations between climate and species ranges. Our results demonstrate that the incorporation of these migration rates greatly change the distributions that could be expected over the next 500 years. The effect of such migration rates have not been considered in models of future carbon balance, yet their history suggests that their importance may outweigh many other variables. Models incorporating migration should be even more important in the projection of future distributions of boreal species across expansive Arctic regions.

First direct evidence of long-distance seasonal movements and hibernation in a migratory bat

Treesearch

Theodore J. Weller; Kevin T. Castle; Felix Liechti; Cris D. Hein; Michael R. Schirmacher; Paul M. Cryan

2016-01-01

Understanding of migration in small bats has been constrained by limitations of techniques that were labor-intensive, provided coarse levels of resolution, or were limited to population-level inferences. Knowledge of movements and behaviors of individual bats have been unknowable because of limitations in size of tracking devices and methods to attach them for...

ON THE MIGRATION OF JUPITER AND SATURN: CONSTRAINTS FROM LINEAR MODELS OF SECULAR RESONANT COUPLING WITH THE TERRESTRIAL PLANETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agnor, Craig B.; Lin, D. N. C.

We examine how the late divergent migration of Jupiter and Saturn may have perturbed the terrestrial planets. Using a modified secular model we have identified six secular resonances between the {nu}{sub 5} frequency of Jupiter and Saturn and the four apsidal eigenfrequencies of the terrestrial planets (g{sub 1-4}). We derive analytic upper limits on the eccentricity and orbital migration timescale of Jupiter and Saturn when these resonances were encountered to avoid perturbing the eccentricities of the terrestrial planets to values larger than the observed ones. Because of the small amplitudes of the j = 2, 3 terrestrial eigenmodes the g{submore » 2} - {nu}{sub 5} and g{sub 3} - {nu}{sub 5} resonances provide the strongest constraints on giant planet migration. If Jupiter and Saturn migrated with eccentricities comparable to their present-day values, smooth migration with exponential timescales characteristic of planetesimal-driven migration ({tau} {approx} 5-10 Myr) would have perturbed the eccentricities of the terrestrial planets to values greatly exceeding the observed ones. This excitation may be mitigated if the eccentricity of Jupiter was small during the migration epoch, migration was very rapid (e.g., {tau} {approx}< 0.5 Myr perhaps via planet-planet scattering or instability-driven migration) or the observed small eccentricity amplitudes of the j = 2, 3 terrestrial modes result from low probability cancellation of several large amplitude contributions. Results of orbital integrations show that very short migration timescales ({tau} < 0.5 Myr), characteristic of instability-driven migration, may also perturb the terrestrial planets' eccentricities by amounts comparable to their observed values. We discuss the implications of these constraints for the relative timing of terrestrial planet formation, giant planet migration, and the origin of the so-called Late Heavy Bombardment of the Moon 3.9 {+-} 0.1 Ga ago. We suggest that the simplest way to satisfy these dynamical constraints may be for the bulk of any giant planet migration to be complete in the first 30-100 Myr of solar system history.« less

Tumor cell migration screen identifies SRPK1 as breast cancer metastasis determinant

PubMed Central

van Roosmalen, Wies; Le Dévédec, Sylvia E.; Golani, Ofra; Smid, Marcel; Pulyakhina, Irina; Timmermans, Annemieke M.; Look, Maxime P.; Zi, Di; Pont, Chantal; de Graauw, Marjo; Naffar-Abu-Amara, Suha; Kirsanova, Catherine; Rustici, Gabriella; Hoen, Peter A.C. ‘t; Martens, John W.M.; Foekens, John A.; Geiger, Benjamin; van de Water, Bob

2015-01-01

Tumor cell migration is a key process for cancer cell dissemination and metastasis that is controlled by signal-mediated cytoskeletal and cell matrix adhesion remodeling. Using a phagokinetic track assay with migratory H1299 cells, we performed an siRNA screen of almost 1,500 genes encoding kinases/phosphatases and adhesome- and migration-related proteins to identify genes that affect tumor cell migration speed and persistence. Thirty candidate genes that altered cell migration were validated in live tumor cell migration assays. Eight were associated with metastasis-free survival in breast cancer patients, with integrin β3–binding protein (ITGB3BP), MAP3K8, NIMA-related kinase (NEK2), and SHC-transforming protein 1 (SHC1) being the most predictive. Examination of genes that modulate migration indicated that SRPK1, encoding the splicing factor kinase SRSF protein kinase 1, is relevant to breast cancer outcomes, as it was highly expressed in basal breast cancer. Furthermore, high SRPK1 expression correlated with poor breast cancer disease outcome and preferential metastasis to the lungs and brain. In 2 independent murine models of breast tumor metastasis, stable shRNA-based SRPK1 knockdown suppressed metastasis to distant organs, including lung, liver, and spleen, and inhibited focal adhesion reorganization. Our study provides comprehensive information on the molecular determinants of tumor cell migration and suggests that SRPK1 has potential as a drug target for limiting breast cancer metastasis. PMID:25774502

Vertical migration and nighttime distribution of adult bloaters in Lake Michigan

USGS Publications Warehouse

TeWinkel, Leslie M.; Fleischer, Guy W.

1999-01-01

The vertical migration and nighttime vertical distribution of adult bloaters Coregonus hoyi were investigated during late summer in Lake Michigan using acoustics simultaneously with either midwater or bottom trawling. Bloaters remained on or near bottom during the day. At night, bloaters were distributed throughout 30-65 m of water, depending on bottom depth. Shallowest depths of migration were not related to water temperature or incident light. Maximum distances of migration increased with increasing bottom depth. Nighttime midwater densities ranged from 0.00 to 6.61 fish/1,000 mA? and decreased with increasing bottom depth. Comparisons of length distributions showed that migrating and nonmigrating bloaters did not differ in size. However, at most sites, daytime bottom catches collected a greater proportion of larger individuals compared with nighttime midwater or bottom catches. Mean target strengths by 5-m strata indicated that migrating bloaters did not stratify by size in the water column at night. Overall, patterns in frequency of empty stomachs and mean digestive state of prey indicated that a portion of the bloater population fed in the water column at night. Bloater diet composition indicated both midwater feeding and bottom feeding. In sum, although a portion of the bloater population fed in the water column at night, bloaters were not limited to feeding at this time. This research confirmed that bloaters are opportunistic feeders and did not fully support the previously proposed hypothesis that bloater vertical migration is driven by the vertically migrating macroinvertebrate the opossom shrimp Mysis relicta.

Nurses on the Move: A Global Overview

PubMed Central

Kingma, Mireille

2007-01-01

Objective To look at nurse migration flows in the light of national nursing workforce imbalances, examine factors that encourage or inhibit nurse mobility, and explore the potential benefits of circular migration. Principal Findings The number of international migrants has doubled since 1970 and nurses are increasingly part of the migratory stream. Critical nursing shortages in industrialized countries are generating a demand that is fueling energetic international recruitment campaigns. Structural adjustments in the developing countries have created severe workforce imbalances and shortfalls often coexist with large numbers of unemployed health professionals. A nurse's motivation to migrate is multifactorial, not limited to financial incentives, and barriers exist that discourage or slow the migration process. The migration flows vary in direction and magnitude over time, responding to socioeconomic factors present in source and destination countries. The dearth of data on which to develop international health human resource policy remains. There is growing recognition, however, that migration will continue and that temporary migration will be a focus of attention in the years to come. Conclusions Today's search for labor is a highly organized global hunt for talent that includes nurses. International migration is a symptom of the larger systemic problems that make nurses leave their jobs. Nurse mobility becomes a major issue only in a context of migrant exploitation or nursing shortage. Injecting migrant nurses into dysfunctional health systems—ones that are not capable of attracting and retaining staff domestically—will not solve the nursing shortage. PMID:17489915

Nocturnally migrating songbirds drift when they can and compensate when they must.

PubMed

Horton, Kyle G; Van Doren, Benjamin M; Stepanian, Phillip M; Hochachka, Wesley M; Farnsworth, Andrew; Kelly, Jeffrey F

2016-02-16

The shortest possible migratory route for birds is not always the best route to travel. Substantial research effort has established that birds in captivity are capable of orienting toward the direction of an intended goal, but efforts to examine how free-living birds use navigational information under conditions that potentially make direct flight toward that goal inefficient have been limited in spatiotemporal scales and in the number of individuals observed because of logistical and technological limitations. Using novel and recently developed techniques for analysis of Doppler polarimetric weather surveillance radar data, we examined two impediments for nocturnally migrating songbirds in eastern North America following shortest-distance routes: crosswinds and oceans. We found that migrants in flight often drifted sideways on crosswinds, but most strongly compensated for drift when near the Atlantic coast. Coastal migrants' tendency to compensate for wind drift also increased through the night, while no strong temporal differences were observed at inland sites. Such behaviors suggest that birds migrate in an adaptive way to conserve energy by assessing while airborne the degree to which they must compensate for wind drift.

Does Selective Migration Explain the Hispanic Paradox?: A Comparative Analysis of Mexicans in the U.S. and Mexico

PubMed Central

Bostean, Georgiana

2014-01-01

Latino immigrants, particularly Mexican, have some health advantages over U.S.-born Mexicans and Whites. Because of their lower socioeconomic status, this phenomenon has been called the epidemiologic “Hispanic Paradox.” While cultural theories have dominated explanations for the Paradox, the role of selective migration has been inadequately addressed. This study is among the few to combine Mexican and U.S. data to examine health selectivity in activity limitation, self-rated health, and chronic conditions among Mexican immigrants, ages 18 and over. Drawing on theories of selective migration, this study tested the “healthy migrant” and “salmon-bias” hypotheses by comparing the health of Mexican immigrants in the U.S. to non-migrants in Mexico, and to return migrants in Mexico. Results suggest that there are both healthy migrant and salmon-bias effects in activity limitation, but not other health aspects. In fact, consistent with prior research, immigrants are negatively selected on self-rated health. Future research should consider the complexities of migrants’ health profiles and examine selection mechanisms alongside other factors such as acculturation. PMID:22618355

Does selective migration explain the Hispanic paradox? A comparative analysis of Mexicans in the U.S. and Mexico.

PubMed

Bostean, Georgiana

2013-06-01

Latino immigrants, particularly Mexican, have some health advantages over U.S.-born Mexicans and Whites. Because of their lower socioeconomic status, this phenomenon has been called the epidemiologic "Hispanic Paradox." While cultural theories have dominated explanations for the Paradox, the role of selective migration has been inadequately addressed. This study is among the few to combine Mexican and U.S. data to examine health selectivity in activity limitation, self-rated health, and chronic conditions among Mexican immigrants, ages 18 and over. Drawing on theories of selective migration, this study tested the "healthy migrant" and "salmon-bias" hypotheses by comparing the health of Mexican immigrants in the U.S. to non-migrants in Mexico, and to return migrants in Mexico. Results suggest that there are both healthy migrant and salmon-bias effects in activity limitation, but not other health aspects. In fact, consistent with prior research, immigrants are negatively selected on self-rated health. Future research should consider the complexities of migrants' health profiles and examine selection mechanisms alongside other factors such as acculturation.

Analysis of 16 phthalic acid esters in food simulants from plastic food contact materials by LC-ESI-MS/MS.

PubMed

Li, Xiaojing; Xiong, Wenming; Lin, Hua; Zhuo, Liyang; Lv, Shuiyuan; Tang, Xi; Chen, Minshi; Zou, Zhexiang; Lin, Zhenyu; Qiu, Bin; Chen, Guonan

2013-02-01

An RP LC-ESI-MS/MS method for the determination of the migration of 16 primary phthalic acid esters from plastic samples has been developed using distilled water, 3% acetic acid, 10% alcohol, and olive oil as food simulants. Detection limits were 1.6-18.5 μg/kg in distilled water, 1.4-17.3 μg/kg in 3% acetic acid, 1.4-19.2 μg/kg in 10% alcohol, and 31.9-390.8 μg/kg in olive oil. The RSDs were in the range of 0.07-11.28%. The real plastic products inspection showed that only few analyzed samples were phthalates contaminated. Bis-2-ethylhexyl ester and dibutyl phthalate were the common items migrated from the plastic products into food and feeds, but the migration concentrations were far below the limits set by European Union (1.5 mg/kg for bis-2-ethylhexyl ester and 0.3 mg/kg for dibutyl phthalate). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nocturnally migrating songbirds drift when they can and compensate when they must

PubMed Central

Horton, Kyle G.; Van Doren, Benjamin M.; Stepanian, Phillip M.; Hochachka, Wesley M.; Farnsworth, Andrew; Kelly, Jeffrey F.

2016-01-01

The shortest possible migratory route for birds is not always the best route to travel. Substantial research effort has established that birds in captivity are capable of orienting toward the direction of an intended goal, but efforts to examine how free-living birds use navigational information under conditions that potentially make direct flight toward that goal inefficient have been limited in spatiotemporal scales and in the number of individuals observed because of logistical and technological limitations. Using novel and recently developed techniques for analysis of Doppler polarimetric weather surveillance radar data, we examined two impediments for nocturnally migrating songbirds in eastern North America following shortest-distance routes: crosswinds and oceans. We found that migrants in flight often drifted sideways on crosswinds, but most strongly compensated for drift when near the Atlantic coast. Coastal migrants’ tendency to compensate for wind drift also increased through the night, while no strong temporal differences were observed at inland sites. Such behaviors suggest that birds migrate in an adaptive way to conserve energy by assessing while airborne the degree to which they must compensate for wind drift. PMID:26879152

Angle-domain common imaging gather extraction via Kirchhoff prestack depth migration based on a traveltime table in transversely isotropic media

NASA Astrophysics Data System (ADS)

Liu, Shaoyong; Gu, Hanming; Tang, Yongjie; Bingkai, Han; Wang, Huazhong; Liu, Dingjin

2018-04-01

Angle-domain common image-point gathers (ADCIGs) can alleviate the limitations of common image-point gathers in an offset domain, and have been widely used for velocity inversion and amplitude variation with angle (AVA) analysis. We propose an effective algorithm for generating ADCIGs in transversely isotropic (TI) media based on the gradient of traveltime by Kirchhoff pre-stack depth migration (KPSDM), as the dynamic programming method for computing the traveltime in TI media would not suffer from the limitation of shadow zones and traveltime interpolation. Meanwhile, we present a specific implementation strategy for ADCIG extraction via KPSDM. Three major steps are included in the presented strategy: (1) traveltime computation using a dynamic programming approach in TI media; (2) slowness vector calculation by the gradient of a traveltime table calculated previously; (3) construction of illumination vectors and subsurface angles in the migration process. Numerical examples are included to demonstrate the effectiveness of our approach, which henceforce shows its potential application for subsequent tomographic velocity inversion and AVA.

Migration limits for children's toys are nothing to play with.

PubMed

Krätke, Renate; Beausoleil, Claire; Carroquino, Maria José; Duarte-Davidson, Raquel; Fernandes, Teresa; Schoeters, Greet

2016-10-01

The European Commission and its independent Scientific Committee on Health and Environmental Risks (SCHER) published their final Opinion on estimates of the amount of toy materials ingested by children. The SCHER was asked to review available data on the ingestion of the following three types of toy material by children, and evaluate whether the ingestion amounts which formed the basis for the migration limits of 19 elements in the Toy Safety Directive are still appropriate or whether they should be changed. In the final Opinion the SCHER considers the ingestion amounts mentioned above to be appropriate, and that these ingestion amounts should remain classified as daily amounts rather than weekly. Copyright © 2016 Elsevier Inc. All rights reserved.

Survey on Metals Contained in Stainless Steel Kitchenware and Tableware.

PubMed

Shiozawa, Yuu; Haneishi, Nahoko; Suzuki, Kumi; Ogimoto, Mami; Takanashi, Mayu; Tomioka, Naoko; Uematsu, Yoko; Monma, Kimio

2017-01-01

Stainless steel kitchenware and tableware on sale in Japan were investigated. Surface elemental composition ratios of 172 samples were analyzed by the fluorescence X-ray method. High levels of manganese (9.59-20.03%)were detected in 17 samples. This finding was confirmed by ICP analysis. Next, we conducted migration tests. Samples conformed to the Italian Specific Migration Limits. Moreover, lead and antimony were not detected in these samples, in accordance with the Japanese Food Sanitation Law.

The importance of workforce surveillance, research evidence and political advocacy in the context of international migration of dentists.

PubMed

Balasubramanian, M; Brennan, D S; Spencer, A J; Watkins, K; Short, S D

2015-03-01

The international migration of dentists is an issue of pressing significance that poses several complex policy challenges. Policy-making is mainly constrained by the lack of workforce surveillance, research evidence and political advocacy - all three are required to work together, yet with different purposes. We first discuss the inconsistencies in migrant dentist surveillance in major country-level governmental systems (immigration departments, dentist registration authorities and workforce agencies). We argue that the limitations in surveillance collections affect independent research and in turn scholarly contributions to dental workforce policy. Differences in country-level surveillance collections also hinder valid cross-country comparisons on migrant dentist data, impeding global policy efforts. Due to these limitations, advocacy, or the political process to influence health policy, suffers, but is integral to future challenges on dentist migration. Country-level advocacy is best targeted at improving migrant dentist surveillance systems. Research interest can be invigorated through targeted funding allocations for migration research and by improving the availability of dentist surveillance data for research purposes. At the global level, the WHOs global code of practice for international recruitment of health personnel (a crucial advocacy tool) needs to be strengthened. Global organisations such as the FDI World Dental Federation have an important role to play in advocating for improved migrant dentist workforce surveillance and research evidence, especially in low- and middle-income countries.

Kinesin-5, a mitotic microtubule-associated motor protein, modulates neuronal migration

PubMed Central

Falnikar, Aditi; Tole, Shubha; Baas, Peter W.

2011-01-01

Kinesin-5 (also called Eg5 or kif11) is a homotetrameric motor protein that functions by modulating microtubule (MT)–MT interactions. In the case of mitosis, kinesin-5 slows the rate of separation of the half-spindles. In the case of the axon, kinesin-5 limits the frequency of transport of short MTs, and also limits the rate of axonal growth. Here we show that experimental inhibition of kinesin-5 in cultured migratory neurons results in a faster but more randomly moving neuron with a shorter leading process. As is the case with axons of stationary neurons, short MT transport frequency is notably enhanced in the leading process of the migratory neuron when kinesin-5 is inhibited. Conversely, overexpression of kinesin-5, both in culture and in developing cerebral cortex, causes migration to slow and even cease. Regions of anti-parallel MT organization behind the centrosome were shown to be especially rich in kinesin-5, implicating these regions as potential sites where kinesin-5 forces may be especially relevant. We posit that kinesin-5 acts as a “brake” on MT–MT interactions that modulates the advance of the entire MT apparatus. In so doing, kinesin-5 regulates the rate and directionality of neuronal migration and possibly the cessation of migration when the neuron reaches its destination. PMID:21411631

Real-Time Observation of Iodide Ion Migration in Methylammonium Lead Halide Perovskites.

PubMed

Li, Cheng; Guerrero, Antonio; Zhong, Yu; Gräser, Anna; Luna, Carlos Andres Melo; Köhler, Jürgen; Bisquert, Juan; Hildner, Richard; Huettner, Sven

2017-11-01

Organic-inorganic metal halide perovskites (e.g., CH 3 NH 3 PbI 3- x Cl x ) emerge as a promising optoelectronic material. However, the Shockley-Queisser limit for the power conversion efficiency (PCE) of perovskite-based photovoltaic devices is still not reached. Nonradiative recombination pathways may play a significant role and appear as photoluminescence (PL) inactive (or dark) areas on perovskite films. Although these observations are related to the presence of ions/defects, the underlying fundamental physics and detailed microscopic processes, concerning trap/defect status, ion migration, etc., still remain poorly understood. Here correlated wide-field PL microscopy and impedance spectroscopy are utilized on perovskite films to in situ investigate both the spatial and the temporal evolution of these PL inactive areas under external electric fields. The formation of PL inactive domains is attributed to the migration and accumulation of iodide ions under external fields. Hence, we are able to characterize the kinetic processes and determine the drift velocities of these ions. In addition, it is shown that I 2 vapor directly affects the PL quenching of a perovskite film, which provides evidence that the migration/segregation of iodide ions plays an important role in the PL quenching and consequently limits the PCE of organometal halide-based perovskite photovoltaic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Does hyperthermia constrain flight duration in a short-distance migrant?

PubMed Central

Guillemette, Magella; Larochelle, Jacques; Polymeropoulos, Elias T.; Granbois, Jean-Marc; Butler, Patrick J.; Pelletier, David; Frappell, Peter B.; Portugal, Steven J.

2016-01-01

While some migratory birds perform non-stop flights of over 11 000 km, many species only spend around 15% of the day in flight during migration, posing a question as to why flight times for many species are so short. Here, we test the idea that hyperthermia might constrain flight duration (FD) in a short-distance migrant using remote biologging technology to measure heart rate, hydrostatic pressure and body temperature in 19 migrating eider ducks (Somateria mollissima), a short-distance migrant. Our results reveal a stop-and-go migration strategy where migratory flights were frequent (14 flights day−1) and short (15.7 min), together with the fact that body temperature increases by 1°C, on average, during such flights, which equates to a rate of heat storage index (HSI) of 4°C h−1. Furthermore, we could not find any evidence that short flights were limited by heart rate, together with the fact that the numerous stops could not be explained by the need to feed, as the frequency of dives and the time spent feeding were comparatively small during the migratory period. We thus conclude that hyperthermia appears to be the predominant determinant of the observed migration strategy, and suggest that such a physiological limitation to FD may also occur in other species. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’. PMID:27528776

Transforming growth factor-{alpha} enhances corneal epithelial cell migration by promoting EGFR recycling.

PubMed

McClintock, Jennifer L; Ceresa, Brian P

2010-07-01

PURPOSE. The goal of this study was to determine the molecular mechanism by which transforming growth factor-alpha (TGF-alpha) is a more potent activator of epidermal growth factor receptor (EGFR)-mediated corneal wound healing than epidermal growth factor (EGF). METHODS. Telomerase immortalized human corneal epithelial (hTCEpi) cells and primary human corneal epithelial cells were tested for their ability to migrate in response to EGF and TGF-alpha. In parallel, the endocytic trafficking of the EGFR in response to these same ligands was examined using indirect immunofluorescence, immunoblots, and radioligand binding. RESULTS. TGF-alpha, compared with EGF, is a more potent activator of corneal epithelial cell migration. Although both TGF-alpha and EGF were able to induce EGFR internalization and phosphorylation, only those receptors that were stimulated with EGF progressed to lysosomal degradation. EGFRs stimulated with TGF-alpha recycled back to the plasma membrane, where they could be reactivated with ligand. CONCLUSIONS. This study reveals that EGFR-mediated cell migration is limited by ligand-stimulated downregulation of the EGFR. This limitation can be overcome by treating cells with TGF-alpha because TGF-alpha stimulates EGFR endocytosis, but not degradation. After internalization of the TGF-alpha/EGFR complex, EGFR recycles back to the plasma membrane, where it can be restimulated. This sequence of events provides the receptor multiple opportunities for stimulation. Thus, stimulation with TGF-alpha prolongs EGFR signaling compared with EGF.

High altitude flights by ruddy shelduck Tadorna ferruginea during trans-Himalayan migrations

USGS Publications Warehouse

Parr, N.; Bearhop, S.; Douglas, David C.; Takekawa, J.Y.; Prosser, Diann J.; Newman, S.H.; Perry, W.M.; Balachandran, S.; Witt, M.J.; Hou, Y.; Luo, Z.; Hawkes, L.A.

2017-01-01

Birds that migrate across high altitude mountain ranges are faced with the challenge of maintaining vigorous exercise in environments with limited oxygen. Ruddy shelducks are known to use wintering grounds south of the Tibetan Plateau at sea level and breeding grounds north of Himalayan mountain range. Therefore, it is likely these shelducks are preforming high altitude migrations. In this study we analyse satellite telemetry data collected from 15 ruddy shelduck from two populations wintering south of the Tibetan Plateau from 2007 to 2011. During north and south migrations ruddy shelduck travelled 1481 km (range 548–2671 km) and 1238 km (range 548–2689 km) respectively. We find mean maximum altitudes of birds in flight reached 5590 m (range of means 4755–6800 m) and mean maximum climb rates of 0.45 m s–1 (range 0.23–0.74 m s–1). The ruddy shelduck is therefore an extreme high altitude migrant that has likely evolved a range of physiological adaptations in order to complete their migrations.

International labor migration and the family: some observations from Indonesia.

PubMed

Hugo, G

1995-01-01

This article addresses two dimensions of the complex interrelationship between the family and international labor migration in Indonesia: the role of the family in influencing labor movements out of Indonesia; and the consequences of this movement on family well-being, structure, and functioning. Research on this topic in Indonesia is highly limited due mainly to the recency of large scale international labor migration, inadequate data collection systems, a high incidence of undocumented migration, and failure of available research to be sensitive to family related issues. Against a rapidly changing economic and social situation, two major overlapping systems of migration have developed. The official system is focused strongly on the Middle East (although other Asian destinations are increasing in significance) and is dominated by female migrants. The undocumented system is much larger in volume, is focused upon Malaysia, involves more males than females, and is becoming permanent in some cases. The role, status, and experiences of women migrants in relation to their families (decision making, networks, remittances) are discussed with recommendations for other areas needing further research attention.

The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration.

PubMed

Parent, Anne-Simone; Teilmann, Grete; Juul, Anders; Skakkebaek, Niels E; Toppari, Jorma; Bourguignon, Jean-Pierre

2003-10-01

During the past decade, possible advancement in timing of puberty has been reported in the United States. In addition, early pubertal development and an increased incidence of sexual precocity have been noticed in children, primarily girls, migrating for foreign adoption in several Western European countries. These observations are raising the issues of current differences and secular trends in timing of puberty in relation to ethnic, geographical, and socioeconomic background. None of these factors provide an unequivocal explanation for the earlier onset of puberty seen in the United States. In the formerly deprived migrating children, refeeding and catch-up growth may prime maturation. However, precocious puberty is seen also in some nondeprived migrating children. Attention has been paid to the changing milieu after migration, and recently, the possible role of endocrine- disrupting chemicals from the environment has been considered. These observations urge further study of the onset of puberty as a possible sensitive and early marker of the interactions between environmental conditions and genetic susceptibility that can influence physiological and pathological processes.

The use of administrative and other records for the analysis of internal migration.

PubMed

1983-01-01

There are 5 main types of administrative records that are of potential use in the analysis of internal migration in Africa: 1) population registers, 2) electoral rolls, 3) school records, 4) labor or employment records, and 5) social security records. The population register provides legal identification for the individual and records his movements from 1 civil subdivision to another. The process of establishing a population register is not a simple one. All 5 of these records are incomplete, defective, and in most cases decentralized; yet, in spite of these limitations, administrative records are potential sources of migration data. Because of their imcompleteness, major biases are likely to arise in their use. The 1st step is for National Statistical Services to assist in improving the coverage of events expected to be registered in any of these records. The 2nd step is to try to use the data through some form of ratio of regression estimation. If use is not made of the records for migration data, it is unlikely that the quality of the migration data in the records will ever improve.

Phytochemicals potently inhibit migration of metastatic breast cancer cells†

PubMed Central

Ham, Stephanie Lemmo; Nasrollahi, Samila; Shah, Kush N.; Soltisz, Andrew; Paruchuri, Sailaja; Yun, Yang H.; Luker, Gary D.; Bishayee, Anupam; Tavana, Hossein

2017-01-01

Cell migration is a major process that drives metastatic progression of cancers, the major cause of cancer death. Existing chemotherapeutic drugs have limited efficacy to prevent and/or treat metastasis, emphasizing the need for new treatments. We focus on triple negative breast cancer (TNBC), the subtype of breast cancer with worst prognosis and no standard chemotherapy protocols. Here we demonstrate that a group of natural compounds, known as phytochemicals, effectively block migration of metastatic TNBC cells. Using a novel cell micropatterning technology, we generate consistent migration niches in standard 96-well plates where each well contains a cell-excluded gap within a uniform monolayer of cells. Over time, cells migrate into and occupy the gap. Treating TNBC cells with non-toxic concentrations of phytochemicals significantly blocks motility of cells. Using a molecular analysis approach, we show that anti-migratory property of phytochemicals is partly due to their inhibitory effects on phosphorylation of ERK1/2. This study provides a framework for future studies to understand molecular targets of phytochemicals and evaluate their effectiveness in inhibiting metastasis in animal models of cancer. PMID:26120051

Migration and sensory properties of plastics-based nets used as food-contacting materials under ambient and high temperature heating conditions.

PubMed

Kontominas, M G; Goulas, A E; Badeka, A V; Nerantzaki, A

2006-06-01

Overall migration from a wide range of commercial plastics-based netting materials destined to be used as either meat or vegetable packaging materials into the fatty food simulant isooctane or the aqueous simulant distilled water, respectively, was studied. In addition, sensory tests of representative netting materials were carried out in bottled water in order to investigate possible development of off-odour/taste and discoloration in this food simulant as a result of migration from the netting material. Sensory tests were supplemented by determination of the volatile compounds' profile in table water exposed to the netting materials using SPME-GC/MS. Test conditions for packaging material/food simulant contact and method of overall migration analysis were according to European Union Directives 90/128 (EEC, 1990) and 2002/72 (EEC, 2002). The results showed that for both PET and polyethylene-based netting materials, overall migration values into distilled water ranged between 11.5 and 48.5 mg l(-1), well below the upper limit (60 mg l(-1)) for overall migration values from plastics-packaging materials set by the European Union. The overall migration values from netting materials into isooctane ranged between 38.0 and 624.0 mg l(-1), both below and above the European Union upper limit for migration. Sensory tests involving contact of representative samples with table water under refluxing (100 degrees C/4 h) conditions showed a number of the netting materials produced both off-odour and/or taste as well as discoloration of the food simulant rendering such materials unfit for the packaging of foodstuffs in applications involving heating at elevated temperatures. GC/MS analysis showed the presence of numerous volatile compounds being produced after netting materials/water contact under refluxing conditions. Although it is extremely difficult to establish a clear correlation between sensory off-odour development and GC/MS volatile compounds' profile, it may be postulated that plastics oxidation products such as hexanal, heptanal, octanal and 2,6 di-tert-butylquinone may contribute to off-odour development using commercially bottled table water as a food simulant. Likewise, compounds such as carbon disulfide, [1,1'-biphenyl]-2-ol and propanoic acid, 2 methyl 1-(1,1-dimethyl)-2-methyl-1,3-propanediyl ester probably originating from cotton and rubber components of netting materials may also contribute to off-odour/taste development.

Comparative use of riparian corridors and oases by migrating birds in southeast Arizona

USGS Publications Warehouse

Skagen, S.K.; Melcher, Cynthia; Howe, W.H.; Knopf, F.L.

1998-01-01

The relative importance of cottonwood-willow riparian corridors and isolated oases to land birds migrating across southeastern Arizona was evaluated during four spring migrations, 1989 to 1994, based on patterns of species richness, relative abundance, density, and body condition of birds. We surveyed birds in 13 study sites ranging in size and connectivity from small isolated patches to extensive riparian forest, sampled vegetation and insects, and captured birds in mistnets. The continuous band of riparian vegetation along the San Pedro River does not appear to be functioning as a corridor for many migrating species, although it may for a few, namely Yellow-breasted Chats (Icteria virens), Summer Tanagers (Piranga rubra), and Northern Rough-winged Swallows (Steldigopteryx serripennis), which account for fewer than 10% of the individuals migrating through the area. Small, isolated oases hosted more avian species than the corridor sites, and the relative abundances of most migrating birds did not differ between sites relative to size-connectivity. There were few differences in between-year variability in the relative abundances of migrating birds between corridor and oasis sites. Between-year variability decreased with overall abundance of species and was greater for species with breeding ranges that centered north of 50??N latitude. Body condition of birds did not differ relative to the size-connectivity of the capture site, but individuals of species with more northerly breeding ranges had more body fat than species that breed nearby. Peak migration densities of several bird species far exceeded breeding densities reported for the San Pedro River, suggesting that large components of these species were en route migrants. Peak densities of Yellow Warblers (Dendroica petechia) reached 48.0 birds/ha, of Wilson's Warblers (Wilsonia pusilla) 33.7 birds/ha, and of Yellow-rumped Warblers (D. coronata) 30.1 birds/ha. Riparian vegetation is limited in extent in the vicinity of our study sites, covering less than 1% of the landscape. We conclude that all riparian patches in southeastern Arizona are important as stopover sites to en route migrants regardless of their size and degree of isolation or connectivity. In light of potential habitat limitation, the protection of both small, disjunct riparian patches and extensive riverine tracts in western landscapes is imperative.

Are Plant Species Able to Keep Pace with the Rapidly Changing Climate?

PubMed Central

Cunze, Sarah; Heydel, Felix; Tackenberg, Oliver

2013-01-01

Future climate change is predicted to advance faster than the postglacial warming. Migration may therefore become a key driver for future development of biodiversity and ecosystem functioning. For 140 European plant species we computed past range shifts since the last glacial maximum and future range shifts for a variety of Intergovernmental Panel on Climate Change (IPCC) scenarios and global circulation models (GCMs). Range shift rates were estimated by means of species distribution modelling (SDM). With process-based seed dispersal models we estimated species-specific migration rates for 27 dispersal modes addressing dispersal by wind (anemochory) for different wind conditions, as well as dispersal by mammals (dispersal on animal's coat – epizoochory and dispersal by animals after feeding and digestion – endozoochory) considering different animal species. Our process-based modelled migration rates generally exceeded the postglacial range shift rates indicating that the process-based models we used are capable of predicting migration rates that are in accordance with realized past migration. For most of the considered species, the modelled migration rates were considerably lower than the expected future climate change induced range shift rates. This implies that most plant species will not entirely be able to follow future climate-change-induced range shifts due to dispersal limitation. Animals with large day- and home-ranges are highly important for achieving high migration rates for many plant species, whereas anemochory is relevant for only few species. PMID:23894290

Comparing Habitat Suitability and Connectivity Modeling Methods for Conserving Pronghorn Migrations

PubMed Central

Poor, Erin E.; Loucks, Colby; Jakes, Andrew; Urban, Dean L.

2012-01-01

Terrestrial long-distance migrations are declining globally: in North America, nearly 75% have been lost. Yet there has been limited research comparing habitat suitability and connectivity models to identify migration corridors across increasingly fragmented landscapes. Here we use pronghorn (Antilocapra americana) migrations in prairie habitat to compare two types of models that identify habitat suitability: maximum entropy (Maxent) and expert-based (Analytic Hierarchy Process). We used distance to wells, distance to water, NDVI, land cover, distance to roads, terrain shape and fence presence to parameterize the models. We then used the output of these models as cost surfaces to compare two common connectivity models, least-cost modeling (LCM) and circuit theory. Using pronghorn movement data from spring and fall migrations, we identified potential migration corridors by combining each habitat suitability model with each connectivity model. The best performing model combination was Maxent with LCM corridors across both seasons. Maxent out-performed expert-based habitat suitability models for both spring and fall migrations. However, expert-based corridors can perform relatively well and are a cost-effective alternative if species location data are unavailable. Corridors created using LCM out-performed circuit theory, as measured by the number of pronghorn GPS locations present within the corridors. We suggest the use of a tiered approach using different corridor widths for prioritizing conservation and mitigation actions, such as fence removal or conservation easements. PMID:23166656

Comparing habitat suitability and connectivity modeling methods for conserving pronghorn migrations.

PubMed

Poor, Erin E; Loucks, Colby; Jakes, Andrew; Urban, Dean L

2012-01-01

Terrestrial long-distance migrations are declining globally: in North America, nearly 75% have been lost. Yet there has been limited research comparing habitat suitability and connectivity models to identify migration corridors across increasingly fragmented landscapes. Here we use pronghorn (Antilocapra americana) migrations in prairie habitat to compare two types of models that identify habitat suitability: maximum entropy (Maxent) and expert-based (Analytic Hierarchy Process). We used distance to wells, distance to water, NDVI, land cover, distance to roads, terrain shape and fence presence to parameterize the models. We then used the output of these models as cost surfaces to compare two common connectivity models, least-cost modeling (LCM) and circuit theory. Using pronghorn movement data from spring and fall migrations, we identified potential migration corridors by combining each habitat suitability model with each connectivity model. The best performing model combination was Maxent with LCM corridors across both seasons. Maxent out-performed expert-based habitat suitability models for both spring and fall migrations. However, expert-based corridors can perform relatively well and are a cost-effective alternative if species location data are unavailable. Corridors created using LCM out-performed circuit theory, as measured by the number of pronghorn GPS locations present within the corridors. We suggest the use of a tiered approach using different corridor widths for prioritizing conservation and mitigation actions, such as fence removal or conservation easements.

Migration characteristics and early clinical results of a novel-finned press-fit acetabular cup.

PubMed

Kaipel, Martin; Prenner, Anton; Bachl, Sebastian; Farr, Sebastian; Sinz, Günter

2014-04-01

Ana Nova® is a novel-finned press-fit acetabular cup which showed superior biomechanical characteristics in an experimental set-up. Using Einzel Bild Röntgen Analyse (EBRA) measurements should offer the opportunity to predict implant survival at an early stage. The purpose of this study was to assess migration and clinical outcome 2 years after total hip replacement by a novel-finned press-fit acetabular cup. In this study, migration and clinical results of the implant were prospectively assessed in 67 patients. Clinical outcome was assessed using the Harris hip score (HHS). Migration analyses were performed using the computer assisted EBRA system. Data were analyzed for normal distribution using the Kolmogorov-Smirnov test. Group comparisons were performed using the analysis of variance (ANOVA) test. P-values less than 0.05 were considered statistically significant. At 2 years after surgery, none of the implants needed revision and HHS increased from 39.7 up to 92.2. In contrast to the beneficial clinical outcome, 17 of 44 patients showed increased total migration ( 1 mm/2a). Adverse migration data in this study might predict aseptic loosening and decreased survival of the implant. According to previous studies, it is possible that this effect occurred because of limited accuracy of the EBRA system. In our opinion, migration analyses may not be recommended as a screening tool in a 2 year follow-up.

Arthropods and associated arthropod-borne diseases transmitted by migrating birds. The case of ticks and tick-borne pathogens.

PubMed

Sparagano, Olivier; George, David; Giangaspero, Annunziata; Špitalská, Eva

2015-09-30

Geographic spread of parasites and pathogens poses a constant risk to animal health and welfare, particularly given that climate change is expected to potentially expand appropriate ranges for many key species. The spread of deleterious organisms via trade routes and human travelling is relatively closely controlled, though represents only one possible means of parasite/pathogen distribution. The transmission via natural parasite/pathogen movement between geographic locales, is far harder to manage. Though the extent of such movement may be limited by the relative inability of many parasites and pathogens to actively migrate, passive movement over long distances may still occur via migratory hosts. This paper reviews the potential role of migrating birds in the transfer of ectoparasites and pathogens between geographic locales, focusing primarily on ticks. Bird-tick-pathogen relationships are considered, and evidence provided of long-range parasite/pathogen transfer from one location to another during bird migration events. As shown in this paper not only many different arthropod species are carried by migrating birds but consequently these pests carry many different pathogens species which can be transmitted to the migrating birds or to other animal species when those arthropods are dropping during these migrations. Data available from the literature are provided highlighting the need to understand better dissemination paths and disease epidemiology. Copyright © 2015 Elsevier B.V. All rights reserved.

Ab initio and kinetic Monte Carlo study of lithium diffusion in LiSi, Li12Si7, Li13Si5 and Li15Si4

NASA Astrophysics Data System (ADS)

Moon, Janghyuk; Lee, Byeongchan; Cho, Maenghyo; Cho, Kyeongjae

2016-10-01

The kinetics of lithium atoms in various Li-Si binary compounds are investigated using density functional theory calculations and kinetic Monte Carlo calculations. The values of the Li migration energy barriers are identified by NEB calculations with vacancy-mediated, interstitial and exchange migration mechanisms in crystalline LiSi, Li12Si7, Li13Si4, and Li15Si4. A comparison of these NEB results shows that the vacancy-mediated Li migration is identified as the dominant diffusion mechanisms in Li-Si compounds. The diffusion coefficients of Li in Li-Si compounds at room temperature are determined by KMC simulation. From the KMC results, the recalculated migration energy barriers in LiSi, Li12Si7, Li13Si4, and Li15Si4 correspond to 0.306, 0.301, 0.367 and 0.320 eV, respectively. Compared to the Li migration energy barrier of 0.6 eV in crystalline Si, the drastic reduction in the Li migration energy barriers in the lithiated silicon indicates that the initial lithiation of the Si anode is the rate-limiting step. Furthermore, it is also found that Si migration is possible in Li-rich configurations. On the basis of these findings, the underlying mechanisms of kinetics on the atomic scale details are elucidated.

The contribution of ecosystem services to place utility as a determinant of migration decision-making

NASA Astrophysics Data System (ADS)

Adams, Helen; Adger, W. Neil

2013-03-01

Environment migration research has sought to provide an account of how environmental risks and resources affect migration and mobility. Part of that effort has focused on the role of the environment in providing secure livelihoods through provisioning ecosystem services. However, many of the models of environment migration linkages fail to acknowledge the importance of social and psychological factors in the decision to migrate. Here, we seek to provide a more comprehensive model of migration decision-making under environmental change by investigating the attachment people form to place, and the role of the environment in creating that attachment. We hypothesize that environmental factors enter the migration decision-making process through their contribution to place utility, defined as a function of both affective and instrumental bonds to location, and that ecosystem services, the aspects of ecosystems that create wellbeing, contribute to both components of place utility. We test these ideas in four rural highland settlements in Peru sampled along an altitudinal gradient. We find that non-economic ecosystem services are important in creating place attachment and that ecological place attachment exists independently of use of provisioning ecosystem services. Individuals’ attitudes to ecosystem services vary with the type of ecosystem services available at a location and the degree of rurality. While social and economic factors are the dominant drivers of migration in these locations, a loss of non-provisioning ecosystem services leads to a decrease in place utility and commitment to place, determining factors in the decision to migrate. The findings suggest that policy interventions encouraging migration as an adaptation to environmental change will have limited success if they only focus on provisioning services. A much wider set of individuals will experience a decrease in place utility, and migration will be unable to alleviate that decrease since the factors that create it are specific to place.

Supplemental feeding alters migration of a temperate ungulate.

PubMed

Jones, Jennifer D; Kauffman, Matthew J; Monteith, Kevin L; Scurlock, Brandon M; Albeke, Shannon E; Cross, Paul C

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that management practices applied in one season may have unintended behavioral consequences in subsequent seasons.

Supplemental feeding alters migration of a temperate ungulate

USGS Publications Warehouse

Jones, Jennifer D; Kauffman, Matthew J.; Monteith, Kevin L.; Scurlock, Brandon M.; Albeke, Shannon E.; Cross, Paul C.

2014-01-01

Conservation of migration requires information on behavior and environmental determinants. The spatial distribution of forage resources, which migration exploits, often are altered and may have subtle, unintended consequences. Supplemental feeding is a common management practice, particularly for ungulates in North America and Europe, and carryover effects on behavior of this anthropogenic manipulation of forage are expected in theory, but have received limited empirical evaluation, particularly regarding effects on migration. We used global positioning system (GPS) data to evaluate the influence of winter feeding on migration behavior of 219 adult female elk (Cervus elaphus) from 18 fed ranges and 4 unfed ranges in western Wyoming. Principal component analysis revealed that the migratory behavior of fed and unfed elk differed in distance migrated, and the timing of arrival to, duration on, and departure from summer range. Fed elk migrated 19.2 km less, spent 11 more days on stopover sites, arrived to summer range 5 days later, resided on summer range 26 fewer days, and departed in the autumn 10 days earlier than unfed elk. Time-to-event models indicated that differences in migratory behavior between fed and unfed elk were caused by altered sensitivity to the environmental drivers of migration. In spring, unfed elk migrated following plant green-up closely, whereas fed elk departed the feedground but lingered on transitional range, thereby delaying their arrival to summer range. In autumn, fed elk were more responsive to low temperatures and precipitation events, causing earlier departure from summer range than unfed elk. Overall, supplemental feeding disconnected migration by fed elk from spring green-up and decreased time spent on summer range, thereby reducing access to quality forage. Our findings suggest that ungulate migration can be substantially altered by changes to the spatial distribution of resources, including those of anthropogenic origin, and that management practices applied in one season may have unintended behavioral consequences in subsequent seasons.

Optimism and challenge for science-based conservation of migratory species in and out of U.S. National Parks.

PubMed

Berger, Joel; Cain, Steven L; Cheng, Ellen; Dratch, Peter; Ellison, Kevin; Francis, John; Frost, Herbert C; Gende, Scott; Groves, Craig; Karesh, William A; Leslie, Elaine; Machlis, Gary; Medellin, Rodrigo A; Noss, Reed F; Redford, Kent H; Soukup, Michael; Wilcove, David; Zack, Steve

2014-02-01

Public agencies sometimes seek outside guidance when capacity to achieve their mission is limited. Through a cooperative agreement and collaborations with the U.S. National Park Service (NPS), we developed recommendations for a conservation program for migratory species. Although NPS manages ∼ 36 million hectares of land and water in 401 units, there is no centralized program to conserve wild animals reliant on NPS units that also migrate hundreds to thousands of kilometers beyond parks. Migrations are imperiled by habitat destruction, unsustainable harvest, climate change, and other impediments. A successful program to counter these challenges requires public support, national and international outreach, and flourishing migrant populations. We recommended two initial steps. First, in the short term, launch or build on a suite of projects for high-profile migratory species that can serve as proof to demonstrate the centrality of NPS units to conservation at different scales. Second, over the longer term, build new capacity to conserve migratory species. Capacity building will entail increasing the limited knowledge among park staff about how and where species or populations migrate, conditions that enable migration, and identifying species' needs and resolving them both within and beyond parks. Building capacity will also require ensuring that park superintendents and staff at all levels support conservation beyond statutory borders. Until additional diverse stakeholders and a broader American public realize what can be lost and do more to protect it and engage more with land management agencies to implement actions that facilitate conservation, long distance migrations are increasingly likely to become phenomena of the past. © 2014 Society for Conservation Biology.

Rapid replacement of riparian rainforest habitat and the impacts on the meandering dynamics of the Kinabatangan River, Borneo

NASA Astrophysics Data System (ADS)

Horton, Alexander J.; Constantine, José A.

2014-05-01

Meandering rivers are defined by their nature to migrate, remobilising floodplain sediment and constructing new surfaces for riparian vegetation to colonise. The presence of riparian vegetation has long been known to limit the ability of rivers to erode riverbanks, but it has remained unclear the principal means by which vegetation provides this function. As a result, most models that predict meandering behaviour do not fully incorporate vegetation, thereby limiting their utility where forest is rapidly replaced. The problem is particularly acute along the Kinabatangan River of Sabah in Malaysian Borneo, where oil palm plantations are replacing one of the oldest riparian rainforests on the planet. The area of Sabah has seen rapid and extensive land use change in the last 40 years, as virgin rainforest has been systematically cleared for logging, and to make way for oil palm plantations. In the 18 years from 1990 to 2008, Sabah lost half of its intact rainforest, which equates to more than 1.85 million hectares. Using Landsat imagery dating back to 1973, we report here the impacts of this rapid land-use change on rates of meander migration on a 280-km reach of the Kinabatangan River. The river planform has been remarkably stable throughout the time period of study, but individual meanders show a rapid response to large discharge events, migrating over an order of magnitude faster than nearby reaches. Rapidly migrating meanders generally occur along portions of floodplain that have been artificially cleared of riparian vegetation, potentially resulting in significant increases in sediment load and within-channel bar development. A field campaign is planned to investigate the mechanisms by which riparian vegetation effect meander migration in these tropical regions.

Stopover ecology of a migratory ungulate

USGS Publications Warehouse

Sawyer, Hall; Kauffman, Matthew J.

2011-01-01

1. Birds that migrate long distances use stopover sites to optimize fuel loads and complete migration as quickly as possible. Stopover use has been predicted to facilitate a time-minimization strategy in land migrants as well, but empirical tests have been lacking, and alternative migration strategies have not been considered. 2. We used fine-scale movement data to evaluate the ecological role of stopovers in migratory mule deer Odocoileus hemionus— a land migrant whose fitness is strongly influenced by energy intake rather than migration speed. 3. Although deer could easily complete migrations (range 18–144 km) in several days, they took an average of 3 weeks and spent 95% of that time in a series of stopover sites that had higher forage quality than movement corridors. Forage quality of stopovers increased with elevation and distance from winter range. Mule deer use of stopovers corresponded with a narrow phenological range, such that deer occupied stopovers 44 days prior to peak green-up, when forage quality was presumed to be highest. Mule deer used one stopover for every 5∙3 and 6∙7 km travelled during spring and autumn migrations, respectively, and used the same stopovers in consecutive years. 4. Study findings indicate that stopovers play a key role in the migration strategy of mule deer by allowing individuals to migrate in concert with plant phenology and maximize energy intake rather than speed. Our results suggest that stopover use may be more common among non-avian taxa than previously thought and, although the underlying migration strategies of temperate ungulates and birds are quite different, stopover use is important to both. 5. Exploring the role of stopovers in land migrants broadens the scope of stopover ecology and recognizes that the applied and theoretical benefits of stopover ecology need not be limited to avian taxa.

Space Based Ornithology: On the Wings of Migration and Biophysics

NASA Technical Reports Server (NTRS)

Smith, James A.

2005-01-01

The study of bird migration on a global scale is one of the compelling and challenging problems of modern biology with major implications for human health and conservation biology. Migration and conservation efforts cross national boundaries and are subject to numerous international agreements and treaties. Space based technology offers new opportunities to shed understanding on the distribution and migration of organisms on the planet and their sensitivity to human disturbances and environmental changes. Migration is an incredibly diverse and complex behavior. A broad outline of space based research must address three fundamental questions: (1) where could birds be, i.e. what is their fundamental niche constrained by their biophysical limits? (2) where do we actually find birds, i.e. what is their realizable niche as modified by local or regional abiotic and biotic factors, and (3) how do they get there (and how do we know?), that is what are their migration patterns and associated mechanisms? Our working hypothesis is that individual organism biophysical models of energy and water balance, driven by satellite measurements of spatio-temporal gradients in climate and habitat, will help us to explain the variability in avian species richness and distribution. Dynamic state variable modeling provides one tool for studying bird migration across multiple scales and can be linked to mechanistic models describing the time and energy budget states of migrating birds. Such models yield an understanding of how a migratory flyway and its component habitats function as a whole and link stop-over ecology with biological conservation and management. Further these models provide an ecological forecasting tool for science and application users to address what are the possible consequences of loss of wetlands, flooding, drought or other natural disasters such as hurricanes on avian biodiversity and bird migration.

Indonesia's migration transition.

PubMed

Hugo, G

1995-01-01

This article describes population movements in Indonesia in the context of rapid and marked social and economic change. Foreign investment in Indonesia is increasing, and global mass media is available to many households. Agriculture is being commercialized, and structural shifts are occurring in the economy. Educational levels are increasing, and women's role and status are shifting. Population migration has increased over the decades, both short and long distance, permanent and temporary, legal and illegal, and migration to and between urban areas. This article focuses specifically on rural-to-urban migration and international migration. Population settlements are dense in the agriculturally rich inner areas of Java, Bali, and Madura. Although the rate of growth of the gross domestic product was 6.8% annually during 1969-94, the World Bank ranked Indonesia as a low-income economy in 1992 because of the large population size. Income per capita is US $670. Indonesia is becoming a large exporter of labor to the Middle East, particularly women. The predominance of women as overseas contract workers is changing women's role and status in the family and is controversial due to the cases of mistreatment. Malaysia's high economic growth rate of over 8% per year means an additional 1.3 million foreign workers and technicians are needed. During the 1980s urban growth increased at a very rapid rate. Urban growth tended to occur along corridors and major transportation routes around urban areas. It is posited that most of the urban growth is due to rural-to-urban migration. Data limitations prevent an exact determination of the extent of rural-to-urban migration. More women are estimated to be involved in movements to cities during the 1980s compared to the 1970s. Recruiters and middlemen have played an important role in rural-to-urban migration and international migration.

A novel, ring-connected stent versus conventional GI stents: comparative study of physical properties and migration rates in a canine colon obstruction model.

PubMed

Park, Hong Suk; Choo, In Wook; Seo, Soowon; Hyun, Dongho; Lim, Sooyoun; Kim, Jae J; Hong, Saet-Byul; Min, Byung-Hoon; Do, Young Soo; Choo, Sung Wook; Shin, Sung Wook; Park, Kwang Bo; Cho, Sung Ki

2015-01-01

Migration of stents is one of the most common adverse events in covered stent placement in GI tract obstruction. To compare physical property and migration rates in a canine colon obstruction model among a novel stent and conventional stents. Comparative physical test and animal study. Medical device testing laboratory and animal laboratory. Mongrel dogs (N=26). Surgical colon obstruction followed by placement of a novel (n=13) or conventional (n=13) stent. Physical properties, migration, and adverse events. The novel stent showed better flexibility, as in a physical test of longitudinal compressibility and axial force, than did conventional stents, and it withstood the fatigue test for 10 days. In terms of radial force and tensile strength, the novel stent showed the same or better results than conventional stents. In a canine colon obstruction model, the migration rate of a novel stent was significantly lower than that of a conventional stent (2/13, 15.4% vs 8/13, 61.5%; P=.008). Animal study of limited size. The novel, ring-connected stent is more flexible and more resistant to migration than the conventional stents. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Migration, violence, and safety among migrant sex workers: A qualitative study in two Guatemalan communities

PubMed Central

Rocha-Jiménez, Teresita; Brouwer, Kimberly C.; Silverman, Jay G.; Morales-Miranda, Sonia

2016-01-01

Despite reports of high levels of violence among women migrants in Central America, limited evidence exists regarding the health and safety of migrant sex workers in Central America. This study is based on 16 months of field research (November 2012–February 2015), including ethnographic fieldwork, in-depth interviews, and focus groups conducted with 52 internal and international migrant female sex workers in Tecún Úman and Quetzaltenango, Guatemala, key transit and destination communities for both international and internal migrants. The analysis explored migration-related determinants of susceptibility to violence experienced by migrant sex workers across different phases of migration. Violence in home communities and economic considerations were key drivers of migration. Unsafe transit experiences (e.g., undocumented border crossings) and negative interactions with authorities in destination settings (e.g., extortion) contributed to migrant sex workers’ susceptibility to violence, while enhanced access to information on immigration policies and greater migration and sex work experience were found to enhance agency and resilience. Findings suggest an urgent need for actions that promote migrant sex workers’ safety in communities of origin, transit, and destination, and programmes aimed at preventing and addressing human rights violations within the context of migration and sex work. PMID:27439656

Does migration affect the outcome of inpatient psychotherapy? Results from a retrospective cohort study.

PubMed

Wiborg, Jan F; Ben-Sliman, Eveline; Michalek, Silke; Tress, Wolgang; Joksimovic, Ljiljana

2016-08-01

Reliable data to determine whether migrant patients benefit sufficiently from evidence-based mental health interventions are scarce. Our aim was to examine the effect of migration on the outcome of inpatient psychotherapy. We conducted a retrospective cohort study and predicted the course of the global severity index of the Symptom Checklist 90 during therapy based on data from our routine clinical practice (N=542). We used mixed models for our analysis and included relevant clinical characteristics. One hundred and twenty-one patients of our sample had a history of migration which was consistently associated with more symptoms at baseline assessment. Patients with direct experiences of migration had the highest level of symptoms before therapy but also showed the largest decrease of symptoms during therapy (B=-0.09, SD=0.04, p=0.030). This interaction effect could be accounted for by our clinical variables. Patients with indirect experiences of migration did not differ from other patients in their level of improvement (B=-0.05, SD=0.04, p=0.149). According to our preliminary data, migration does not seem to negatively affect the outcome of inpatient psychotherapy. Limitations of these promising findings are discussed together with the strong need for more advanced studies in this area of research. Copyright © 2016 Elsevier Inc. All rights reserved.

Migration, Remittances, and Educational Stratification among Blacks in Apartheid and Post-Apartheid South Africa.

PubMed

Lu, Yao; Treiman, Donald J

2011-06-01

This paper extends previous work on family structure and children's education by conceptualizing migration as a distinct form of family disruption that reduces parental input but brings substantial economic benefits through remittances. It examines the multiple and countervailing effects of migration on schooling in the context of substantial migration and limited educational opportunities for Blacks in South Africa. The receipt of remittances substantially increases Black children's school attendance, but has no such effect for Whites. The effect for Blacks is in part attributable to improved household economic conditions that increase household educational spending and reduce the demand for child labor. We also find a negative effect of parental absence due to migration, but it is largely cushioned by inflows of remittances. Sensitivity analyses using propensity score methods and contextual fixed-effect modeling suggest that the beneficial effect of remittances is relatively robust. We find further that remittances help ameliorate inter-familial socioeconomic inequality in schooling. Finally, we evaluate possible temporal changes and show that the positive and equalizing effects of remittances persisted during and after the apartheid regime. We conclude that labor migration and remittances, as institutionalized family strategies adopted by many Blacks, help reconfigure structural opportunities in the educational stratification process in South Africa.

Movement, migration, and smolting of Atlantic salmon (Salmo salar)

USGS Publications Warehouse

McCormick, S.D.; Hansen, Lonnie P.; Quinn, T.P.; Saunders, R.L.

1998-01-01

A variety of movements characterize the behavioral plasticity of Atlantic salmon (Salmo salar) in fresh water, including movements of fry from redds, establishment of feeding territories, spawning movements of sexually mature male parr, movement to and from winter habitat, and smolt migration in spring. Smolting is an adaptive specialization for downstream migration, seawater entry, and marine residence. While still in fresh water, smolts become silvery and streamlined, lose their positive rheotaxis and territoriality, and begin schooling. Physiological changes include increased salinity tolerance, olfactory sensitivity, metabolic rate, scope for growth, and altered hemoglobin and visual pigments. Through their impact on the neuroendocrine system, photoperiod and temperature regulate physiological changes, whereas temperature and water flow may initiate migration. Smolt survival is affected by a limited period of readiness (a physiological 'smolt window') and the timing of seawater entry with environmental conditions such as temperature, food, and predators (an ecological 'smolt window'). Smolt development is adversely affected by acidity, pollutants, and improper rearing conditions, and is often more sensitive than other life stages. Unfortunately, the migration corridor of smolts (mainstems of rivers and estuaries) are the most heavily impacted by pollution, dams, and other anthropogenic activities that may be directly lethal or increase mortality by delaying or inhibiting smolt migration.

Migration, Remittances, and Educational Stratification among Blacks in Apartheid and Post-Apartheid South Africa

PubMed Central

Lu, Yao; Treiman, Donald J.

2013-01-01

This paper extends previous work on family structure and children’s education by conceptualizing migration as a distinct form of family disruption that reduces parental input but brings substantial economic benefits through remittances. It examines the multiple and countervailing effects of migration on schooling in the context of substantial migration and limited educational opportunities for Blacks in South Africa. The receipt of remittances substantially increases Black children’s school attendance, but has no such effect for Whites. The effect for Blacks is in part attributable to improved household economic conditions that increase household educational spending and reduce the demand for child labor. We also find a negative effect of parental absence due to migration, but it is largely cushioned by inflows of remittances. Sensitivity analyses using propensity score methods and contextual fixed-effect modeling suggest that the beneficial effect of remittances is relatively robust. We find further that remittances help ameliorate inter-familial socioeconomic inequality in schooling. Finally, we evaluate possible temporal changes and show that the positive and equalizing effects of remittances persisted during and after the apartheid regime. We conclude that labor migration and remittances, as institutionalized family strategies adopted by many Blacks, help reconfigure structural opportunities in the educational stratification process in South Africa. PMID:23935219

Correlation between the outer flow and the turbulent production in a boundary layer

NASA Technical Reports Server (NTRS)

Cliff, W. C.; Sandborn, V. A.

1975-01-01

Space-time velocity correlation measurements between fluctuations occurring in the convoluting outer edge of a flat boundary layer with fluctuations occurring near the viscous subregion were made. The correlations indicate that information is propagated from the outer region to the inner region. The migration of turbulence away from the wall was previously studied in the open literature. The results presented here along with the migration results lend support to the limit cycle model for turbulence production.

The Influence of Seal Properties on Pressure Buildup and Leakage of Carbon Dioxide from Sequestration Reservoirs (Invited)

NASA Astrophysics Data System (ADS)

Benson, S. M.; Chabora, E.

2009-12-01

The transport properties of seals, namely permeability, relative permeability, and capillary pressure control both migration of carbon dioxide and brine through the seal. Only recently has the the importance of brine migration emerged as key issue in the environmental performance of carbon dioxide sequestration projects. In this study we use numerical simulation to show that brine migration through the seal can be either advantageous or deleterious to the environmental performance of a carbon dioxide sequestration project. Brine migration through the seal can lower the pressure buildup in the storage reservoir, thereby reducing the risk of leakage or geomechanical stresses on the seal. On the other hand, if the seal is penetrated by a permeable fault it can lead to focused flow up a fault, which could lead to brine migration into drinking water aquifers. We also show that as the carbon dioxide plume grows, brine flow undergoes a complex evolution from upward flow to downward flows driven by countercurrent migration of carbon dioxide and brine in the seal and capillary pressure gradients at the base of the seal. Finally, we discuss desirable attributes seals, taking into account both carbon dioxide and brine migration through the seal. In particular, identifying seals that provide an effective capillary barrier to block the flow of carbon dioxide while allowing some brine migration through the seal can help to control pressure buildup and allow more efficient utilization of a sequestration reservoir. This could be particularly important in those settings that may be limited by the maximum allowable pressure buildup.

Evolutionary History of Helicobacter pylori Sequences Reflect Past Human Migrations in Southeast Asia

PubMed Central

Breurec, Sebastien; Guillard, Bertrand; Hem, Sopheak; Brisse, Sylvain; Dieye, Fatou Bintou; Huerre, Michel; Oung, Chakravuth; Raymond, Josette; Sreng Tan, Tek; Thiberge, Jean-Michel; Vong, Sirenda; Monchy, Didier; Linz, Bodo

2011-01-01

The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia. PMID:21818291

Measuring the migration of the components and polyethylene wear after total hip arthroplasty: beads and specialised radiographs are not necessary.

PubMed

Devane, P A; Horne, J G; Foley, G; Stanley, J

2017-10-01

This paper describes the methodology, validation and reliability of a new computer-assisted method which uses models of the patient's bones and the components to measure their migration and polyethylene wear from radiographs after total hip arthroplasty (THA). Models of the patient's acetabular and femoral component obtained from the manufacturer and models of the patient's pelvis and femur built from a single computed tomography (CT) scan, are used by a computer program to measure the migration of the components and the penetration of the femoral head from anteroposterior and lateral radiographs taken at follow-up visits. The program simulates the radiographic setup and matches the position and orientation of the models to outlines of the pelvis, the acetabular and femoral component, and femur on radiographs. Changes in position and orientation reflect the migration of the components and the penetration of the femoral head. Validation was performed using radiographs of phantoms simulating known migration and penetration, and the clinical feasibility of measuring migration was assessed in two patients. Migration of the acetabular and femoral components can be measured with limits of agreement (LOA) of 0.37 mm and 0.33 mm, respectively. Penetration of the femoral head can be measured with LOA of 0.161 mm. The migration of components and polyethylene wear can be measured without needing specialised radiographs. Accurate measurement may allow earlier prediction of failure after THA. Cite this article: Bone Joint J 2017;99-B:1290-7. ©2017 The British Editorial Society of Bone & Joint Surgery.

Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia.

PubMed

Breurec, Sebastien; Guillard, Bertrand; Hem, Sopheak; Brisse, Sylvain; Dieye, Fatou Bintou; Huerre, Michel; Oung, Chakravuth; Raymond, Josette; Tan, Tek Sreng; Thiberge, Jean-Michel; Vong, Sirenda; Monchy, Didier; Linz, Bodo

2011-01-01

The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

Taking Limited English Proficient Adults into Account in the Federal Adult Education Funding Formula

ERIC Educational Resources Information Center

Capps, Randy; Fix, Michael; McHugh, Margie; Lin, Serena Yi-Ying

2009-01-01

This new report by Migration Policy Institute's (MPI's) National Center on Immigrant Integration Policy examines the funding formula used to distribute Workforce Investment Act (WIA) Title II federal funds for adult education, literacy, and English as a Second Language instruction. Though all adults with limited English proficiency (LEP) are…

Determination of bisphenol A in food-simulating liquids using LCED with a chemically modified electrode.

PubMed

D'Antuono, A; Dall'Orto, V C; Lo Balbo, A; Sobral, S; Rezzano, I

2001-03-01

Liquid chromatography with electrochemical detector (LC-ED), using a chemically modified electrode coated with a metalloporphyrin film, is reported for determination of bisphenol A (BPA) migration from polycarbonate baby bottles. The extraction process of the samples was performed according to regulations of the Southern Common Market (MERCOSUR), where certain food-simulating liquids [(A) distilled water, (B) acetic acid 3% V/V in distilled water, and (C) ethanol 15% V/V in distilled water] are defined along with controlled time and temperature conditions. The baseline obtained using the naked electrode showed a considerable drift which increased the detection limit. This effect was suppressed with the chemically modified electrode. A linear range up to 450 ppb along with a detection limit of 20 ppb for the amperometric detection technique was observed. The procedure described herein allowed lowering the detection limit of the method to 0.2 ppb. The value found for BPA in the food-simulating liquid is 1.2 ppb, which is below the tolerance limit for specific migration (4.8 ppm).

Electrolyte matrix in a molten carbonate fuel cell stack

DOEpatents

Reiser, C.A.; Maricle, D.L.

1987-04-21

A fuel cell stack is disclosed with modified electrolyte matrices for limiting the electrolytic pumping and electrolyte migration along the stack external surfaces. Each of the matrices includes marginal portions at the stack face of substantially greater pore size than that of the central body of the matrix. Consequently, these marginal portions have insufficient electrolyte fill to support pumping or wicking of electrolyte from the center of the stack of the face surfaces in contact with the vertical seals. Various configurations of the marginal portions include a complete perimeter, opposite edge portions corresponding to the air plenums and tab size portions corresponding to the manifold seal locations. These margins will substantially limit the migration of electrolyte to and along the porous manifold seals during operation of the electrochemical cell stack. 6 figs.

Electrolyte matrix in a molten carbonate fuel cell stack

DOEpatents

Reiser, Carl A.; Maricle, Donald L.

1987-04-21

A fuel cell stack is disclosed with modified electrolyte matrices for limiting the electrolytic pumping and electrolyte migration along the stack external surfaces. Each of the matrices includes marginal portions at the stack face of substantially greater pore size than that of the central body of the matrix. Consequently, these marginal portions have insufficient electrolyte fill to support pumping or wicking of electrolyte from the center of the stack of the face surfaces in contact with the vertical seals. Various configurations of the marginal portions include a complete perimeter, opposite edge portions corresponding to the air plenums and tab size portions corresponding to the manifold seal locations. These margins will substantially limit the migration of electrolyte to and along the porous manifold seals during operation of the electrochemical cell stack.

Migration of Lebanese nurses: a questionnaire survey and secondary data analysis.

PubMed

El-Jardali, Fadi; Dumit, Nuhad; Jamal, Diana; Mouro, Gladys

2008-10-01

Nursing is becoming a mobile profession. Nurse migration is multifactorial and not limited to financial incentives. Non-economic factors that might lead to migration include poor recruitment and retention strategies, poor job satisfaction and working conditions, socio-political and economic stability, and the poor social image of the nursing profession. Lebanon is facing a problem of excessive nurse migration to countries of the Gulf, North America and Europe. No study has been conducted to understand the determinants and magnitude of the problem. The objective of this study is to provide an evidence base for understanding the incidence of nurse migration out of Lebanon, its magnitude and reasons. A cross-sectional research design comprising both quantitative and qualitative methods was employed to achieve the stated objectives. This includes a survey of nursing schools in Lebanon, survey of nurse recruitment agencies, secondary data analysis and survey of migrant nurses. An estimated one in five nurses that receive a bachelors of science in nursing migrates out of Lebanon within 1 or 2 years of graduation. The majority of nurses migrate to countries of the Gulf. The main reasons for migration included: shift work, high patient/nurse ratios, lack of autonomy in decision-making, lack of a supportive environment, and poor commitment to excellent nursing care. Further, nurses reported that combinations of financial and non-financial incentives can encourage them to return to practice in Lebanon. The most recurring incentives (pull factors) to encourage nurses to return to practice in Lebanon included educational support, managerial support, better working conditions, utilization of best nursing practices and autonomy. Nurse migration and retention have become major health workforce issues confronting many health systems in the East Mediterranean Region. Our study demonstrated that nurse migration is a product of poor management and lack of effective retention strategies and sufficient knowledge about the context, needs and challenges facing nurses. Nurse migration in Lebanon underscores the importance of developing a monitoring system that would identify implications and help implement innovative retention strategies. Nurse migration out of Lebanon is likely to persist and even increase if underlying factors are not properly resolved.

The effect of migration on family structures in sub-Saharan Africa.

PubMed

Okoth-ogendo, H W

1989-06-01

This paper assesses the effect of migration or family structures in sub-Saharan Africa, especially the effect of emigration on the reproduction, production, and social stability of the family in areas of origin in the predominantly agrarian communities of East and Southern Africa. Migration in precolonial Africa usually occurred for 1 of the following reasons: 1) the search by communities for new habitats and opportunities; 2) as a community response to droughts, floods, environmental degradation, and similar disasters; and 3) as a result of internecine wars, civil strife, and general hostilities. Thus, because of the collective nature of early migrations, the family unit maintained a much greater degree of social cohesion. The effects of the rise of the modern state in Africa on migration include 1) spatial limits of collective migration were frozen, 2) the colonial boundaries did not always correspond to cultural divisions, 3) both migration within colonial boundaries and individual migration became dominant, and 4) cyclical migration began. The end of colonialism resulted in 1) difficulties in creating strong and internally coherent nation states because of the uncertainty of national borders and 2) more cyclical migrants. The effects of migration on reproduction in the family during the colonial period include 17 extremely low fertility rates, 2) widespread domestic instability, and 3) exacerbation of moral decadence. Contemporary patterns of emigration have been far less disruptive, due in part to increased personal mobility and migration of the complete reproductive unit. The effects of migration on production include 1) depletion of labor for production; 2) women had to assume production functions, together with all their other responsibilities; and 3) very little cash or goods were available for remittance to areas of origin. Production and productivity among rural African families will continue to suffer as long as plantations, mines, and urban centers entice the younger, more productive labor way. Migration can affect the social structure 1) by undermining basic social institutions including the family; or 2) by strengthening social solidarity especially if it occurs in the land frontier of the migrant's original society. Africa's migration policy should 1) allow for greater mobility within and across boundaries and 2) initiate policies and programs to achieve a more balanced settlement pattern, especially in rural Africa.

Migratory life histories explain the extreme egg-size dimorphism of Eudyptes penguins.

PubMed

Crossin, Glenn T; Williams, Tony D

2016-10-12

When successive stages in the life history of an animal directly overlap, physiological conflicts can arise resulting in carryover effects from one stage to another. The extreme egg-size dimorphism (ESD) of Eudyptes penguins, where the first-laid A-egg is approximately 18-57% smaller than the second-laid B-egg, has interested researchers for decades. Recent studies have linked variation in this trait to a carryover effect of migration that limits the physiology of yolk production and egg sizes. We assembled data on ESD and estimates of migration-reproduction overlap in penguin species and use phylogenetic methods to test the idea that migration-reproduction overlap explains variation in ESD. We show that migration overlap is generally restricted to Eudyptes relative to non-Eudyptes penguins, and that this overlap (defined as the amount of time that egg production occurs on land versus at sea during homeward migration) is significantly and positively correlated with the degree of ESD in Eudyptes In the non-Eudyptes species, however, ESD was unrelated to migration overlap as these species mostly produce their clutches on land. Our results support the recent hypothesis that extreme ESD of Eudyptes penguins evolved, in part, as a response to selection for a pelagic overwinter migration behaviour. This resulted in a temporal overlap with, and thus a constraint on, the physiology of follicle development, leading to smaller A-egg size and greater ESD. © 2016 The Author(s).

Constraints on Upward Migration of Hydraulic Fracturing Fluid and Brine

PubMed Central

Flewelling, Samuel A; Sharma, Manu

2014-01-01

Recent increases in the use of hydraulic fracturing (HF) to aid extraction of oil and gas from black shales have raised concerns regarding potential environmental effects associated with predictions of upward migration of HF fluid and brine. Some recent studies have suggested that such upward migration can be large and that timescales for migration can be as short as a few years. In this article, we discuss the physical constraints on upward fluid migration from black shales (e.g., the Marcellus, Bakken, and Eagle Ford) to shallow aquifers, taking into account the potential changes to the subsurface brought about by HF. Our review of the literature indicates that HF affects a very limited portion of the entire thickness of the overlying bedrock and therefore, is unable to create direct hydraulic communication between black shales and shallow aquifers via induced fractures. As a result, upward migration of HF fluid and brine is controlled by preexisting hydraulic gradients and bedrock permeability. We show that in cases where there is an upward gradient, permeability is low, upward flow rates are low, and mean travel times are long (often >106 years). Consequently, the recently proposed rapid upward migration of brine and HF fluid, predicted to occur as a result of increased HF activity, does not appear to be physically plausible. Unrealistically high estimates of upward flow are the result of invalid assumptions about HF and the hydrogeology of sedimentary basins. PMID:23895673

Climate Induced Spillover and Implications for U.S. Security.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tidwell, Vincent C.; Naugle, Asmeret Bier; Backus, George A.

Developing nations incur a greater risk to climate change than the developed world due to poorly managed human/natural resources, unreliable infrastructure and brittle governing/economic institutions. These vulnerabilities often give rise to a climate induced “domino effect” of reduced natural resource production-leading to economic hardship, social unrest, and humanitarian crises. Integral to this cascading set of events is increased human migration, leading to the “spillover” of impacts to adjoining areas with even broader impact on global markets and security. Given the complexity of factors influencing human migration and the resultant spill-over effect, quantitative tools are needed to aid policy analysis. Towardmore » this need, a series of migration models were developed along with a system dynamics model of the spillover effect. The migration decision models were structured according to two interacting paths, one that captured long-term “chronic” impacts related to protracted deteriorating quality of life and a second focused on short-term “acute” impacts of disaster and/or conflict. Chronic migration dynamics were modeled for two different cases; one that looked only at emigration but at a national level for the entire world; and a second that looked at both emigration and immigration but focused on a single nation. Model parameterization for each of the migration models was accomplished through regression analysis using decadal data spanning the period 1960-2010. A similar approach was taken with acute migration dynamics except regression analysis utilized annual data sets limited to a shorter time horizon (2001-2013). The system dynamics spillover model was organized around two broad modules, one simulating the decision dynamics of migration and a second module that treats the changing environmental conditions that influence the migration decision. The environmental module informs the migration decision, endogenously simulating interactions/changes in the economy, labor, population, conflict, water, and food. A regional model focused on Mali in western Africa was used as a test case to demonstrate the efficacy of the model.« less

Robotic Patterning a Superhydrophobic Surface for Collective Cell Migration Screening.

PubMed

Pang, Yonggang; Yang, Jing; Hui, Zhixin; Grottkau, Brian E

2018-04-01

Collective cell migration, in which cells migrate as a group, is fundamental in many biological and pathological processes. There is increasing interest in studying the collective cell migration in high throughput. Cell scratching, insertion blocker, and gel-dissolving techniques are some methodologies used previously. However, these methods have the drawbacks of cell damage, substrate surface alteration, limitation in medium exchange, and solvent interference. The superhydrophobic surface, on which the water contact angle is greater than 150 degrees, has been recently utilized to generate patterned arrays. Independent cell culture areas can be generated on a substrate that functions the same as a conventional multiple well plate. However, so far there has been no report on superhydrophobic patterning for the study of cell migration. In this study, we report on the successful development of a robotically patterned superhydrophobic array for studying collective cell migration in high throughput. The array was developed on a rectangular single-well cell culture plate consisting of hydrophilic flat microwells separated by the superhydrophobic surface. The manufacturing process is robotic and includes patterning discrete protective masks to the substrate using 3D printing, robotic spray coating of silica nanoparticles, robotic mask removal, robotic mini silicone blocker patterning, automatic cell seeding, and liquid handling. Compared with a standard 96-well plate, our system increases the throughput by 2.25-fold and generates a cell-free area in each well non-destructively. Our system also demonstrates higher efficiency than conventional way of liquid handling using microwell plates, and shorter processing time than manual operating in migration assays. The superhydrophobic surface had no negative impact on cell viability. Using our system, we studied the collective migration of human umbilical vein endothelial cells and cancer cells using assays of endpoint quantification, dynamic cell tracking, and migration quantification following varied drug treatments. This system provides a versatile platform to study collective cell migration in high throughput for a broad range of applications.

Assessment of the migration potential of nanosilver from nanoparticle-coated low-density polyethylene food packaging into food simulants.

PubMed

Hannon, Joseph Christopher; Kerry, Joseph P; Cruz-Romero, Malco; Azlin-Hasim, Shafrina; Morris, Michael; Cummins, Enda

2016-01-01

An experimental nanosilver-coated low-density polyethylene (LDPE) food packaging was incubated with food simulants using a conventional oven and tested for migration according to European Commission Regulation No. 10/2011. The commercial LDPE films were coated using a layer-by-layer (LbL) technique and three levels of silver (Ag) precursor concentration (0.5%, 2% and 5% silver nitrate (AgNO3), respectively) were used to attach antimicrobial Ag. The experimental migration study conditions (time, temperature and food simulant) under conventional oven heating (10 days at 60°C, 2 h at 70°C, 2 h at 60°C or 10 days at 70°C) were chosen to simulate the worst-case storage period of over 6 months. In addition, migration was quantified under microwave heating. The total Ag migrant levels in the food simulants were quantified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Mean migration levels obtained by ICP-AES for oven heating were in the range 0.01-1.75 mg l(-1). Migration observed for microwave heating was found to be significantly higher when compared with oven heating for similar temperatures (100°C) and identical exposure times (2 min). In each of the packaging materials and food simulants tested, the presence of nanoparticles (NPs) was confirmed by scanning electron microscopy (SEM). On inspection of the migration observed under conventional oven heating, an important finding was the significant reduction in migration resulting from the increased Ag precursor concentration used to attach Ag on the LDPE LbL-coated films. This observation merits further investigation into the LbL coating process used, as it suggests potential for process modifications to reduce migration. In turn, any reduction in NP migration below regulatory limits could greatly support the antimicrobial silver nanoparticle (AgNP)-LDPE LbL-coated films being used as a food packaging material.

Warming increases plant biomass and reduces diversity across continents, latitudes, and species migration scenarios in experimental wetland communities.

PubMed

Baldwin, Andrew H; Jensen, Kai; Schönfeldt, Marisa

2014-03-01

Atmospheric warming may influence plant productivity and diversity and induce poleward migration of species, altering communities across latitudes. Complicating the picture is that communities from different continents deviate in evolutionary histories, which may modify responses to warming and migration. We used experimental wetland plant communities grown from seed banks as model systems to determine whether effects of warming on biomass production and species richness are consistent across continents, latitudes, and migration scenarios. We collected soil samples from each of three tidal freshwater marshes in estuaries at three latitudes (north, middle, south) on the Atlantic coasts of Europe and North America. In one experiment, we exposed soil seed bank communities from each latitude and continent to ambient and elevated (+2.8 °C) temperatures in the greenhouse. In a second experiment, soil samples were mixed either within each estuary (limited migration) or among estuaries from different latitudes in each continent (complete migration). Seed bank communities of these migration scenarios were also exposed to ambient and elevated temperatures and contrasted with a no-migration treatment. In the first experiment, warming overall increased biomass (+16%) and decreased species richness (-14%) across latitudes in Europe and North America. Species richness and evenness of south-latitude communities were less affected by warming than those of middle and north latitudes. In the second experiment, warming also stimulated biomass and lowered species richness. In addition, complete migration led to increased species richness (+60% in North America, + 100% in Europe), but this higher diversity did not translate into increased biomass. Species responded idiosyncratically to warming, but Lythrum salicaria and Bidens sp. increased significantly in response to warming in both continents. These results reveal for the first time consistent impacts of warming on biomass and species richness for temperate wetland plant communities across continents, latitudes, and migration scenarios. © 2013 John Wiley & Sons Ltd.

Predictive ethoinformatics reveals the complex migratory behaviour of a pelagic seabird, the Manx Shearwater

PubMed Central

Freeman, Robin; Dean, Ben; Kirk, Holly; Leonard, Kerry; Phillips, Richard A.; Perrins, Chris M.; Guilford, Tim

2013-01-01

Understanding the behaviour of animals in the wild is fundamental to conservation efforts. Advances in bio-logging technologies have offered insights into the behaviour of animals during foraging, migration and social interaction. However, broader application of these systems has been limited by device mass, cost and longevity. Here, we use information from multiple logger types to predict individual behaviour in a highly pelagic, migratory seabird, the Manx Shearwater (Puffinus puffinus). Using behavioural states resolved from GPS tracking of foraging during the breeding season, we demonstrate that individual behaviours can be accurately predicted during multi-year migrations from low cost, lightweight, salt-water immersion devices. This reveals a complex pattern of migratory stopovers: some involving high proportions of foraging, and others of rest behaviour. We use this technique to examine three consecutive years of global migrations, revealing the prominence of foraging behaviour during migration and the importance of highly productive waters during migratory stopover. PMID:23635496

Measurements of fluid transport by controllable vertical migrations of plankton

NASA Astrophysics Data System (ADS)

Houghton, Isabel A.; Dabiri, John O.

2016-11-01

Diel vertical migration of zooplankton has been proposed to be a significant contributor to local and possibly large-scale fluid transport in the ocean. However, studies of this problem to date have been limited to order-of-magnitude estimates based on first principles and a small number of field observations. In this work, we leverage the phototactic behavior of zooplankton to stimulate controllable vertical migrations in the laboratory and to study the associated fluid transport and mixing. Building upon a previous prototype system, a laser guidance system induces vertical swimming of brine shrimp (Artemia salina) in a 2.1 meter tall, density-stratified water tank. The animal swimming speed and spacing during the controlled vertical migration is characterized with video analysis. A schlieren imaging system is utilized to visualize density perturbations to a stable stratification for quantification of fluid displacement length scales and restratification timescales. These experiments can add to our understanding of the dynamics of active particles in stratified flows. NSF and US-Israel Binational Science Foundation.

Vertical migration of motile phytoplankton chains through turbulence

NASA Astrophysics Data System (ADS)

Climent, Eric; Lovecchio, Salvatore; Durham, William; Stocker, Roman

2017-11-01

Daily, phytoplankton needs to migrate vertically from and towards the ocean surface to find nutrients such as dissolved oxygen. To travel through the water column they need to fight against gravity (by swimming) and fluid turbulence which can make their journey longer. It is often observed that cells migrate across the water column as chains. The first benefit to form chains is that micro-organisms sum up their thrust while reducing their drag. Therefore, upwards swimming is faster for chains in a quiescent fluid with steady vertical orientation. However, as chain length increases their tendency to periodically tumble in turbulent structures increases which reduces orientation stability and limits their capacity to swim upwards. The purpose of our study is to elaborate on this apparent contradiction. We carried out direct numerical simulations and physical analysis of the coupled system of homogeneous isotropic turbulence and chain trajectories through Lagrangian tracking. Formation of chains is indeed favorable for vertical migration through the upper layer of the ocean.

Measurements of diurnal variations and eddy covariance (EC) fluxes of glyoxal in the tropical marine boundary layer: description of the Fast LED-CE-DOAS instrument

NASA Astrophysics Data System (ADS)

Coburn, S.; Ortega, I.; Thalman, R.; Blomquist, B.; Fairall, C. W.; Volkamer, R.

2014-10-01

Here we present first eddy covariance (EC) measurements of fluxes of glyoxal, the smallest α-dicarbonyl product of hydrocarbon oxidation, and a precursor for secondary organic aerosol (SOA). The unique physical and chemical properties of glyoxal - i.e., high solubility in water (effective Henry's law constant, KH = 4.2 × 105 M atm-1) and short atmospheric lifetime (~2 h at solar noon) - make it a unique indicator species for organic carbon oxidation in the marine atmosphere. Previous reports of elevated glyoxal over oceans remain unexplained by atmospheric models. Here we describe a Fast Light-Emitting Diode Cavity-Enhanced Differential Optical Absorption Spectroscopy (Fast LED-CE-DOAS) instrument to measure diurnal variations and EC fluxes of glyoxal and inform about its unknown sources. The fast in situ sensor is described, and first results are presented from a cruise deployment over the eastern tropical Pacific Ocean (20° N to 10° S; 133 to 85° W) as part of the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO) field experiment (January to March 2012). The Fast LED-CE-DOAS is a multispectral sensor that selectively and simultaneously measures glyoxal (CHOCHO), nitrogen dioxide (NO2), oxygen dimers (O4), and water vapor (H2O) with ~2 Hz time resolution (Nyquist frequency ~1 Hz) and a precision of ~40 pptv Hz-0.5 for glyoxal. The instrument is demonstrated to be a "white-noise" sensor suitable for EC flux measurements. Fluxes of glyoxal are calculated, along with fluxes of NO2, H2O, and O4, which are used to aid the interpretation of the glyoxal fluxes. Further, highly sensitive and inherently calibrated glyoxal measurements are obtained from temporal averaging of data (e.g., detection limit smaller than 2.5 pptv in an hour). The campaign average mixing ratio in the Southern Hemisphere (SH) is found to be 43 ± 9 pptv glyoxal, which is higher than the Northern Hemisphere (NH) average of 32 ± 6 pptv (error reflects variability over multiple days). The diurnal variation of glyoxal in the marine boundary layer (MBL) is measured for the first time, and mixing ratios vary by ~8 pptv (NH) and ~12 pptv (SH) over the course of 24 h. Consistently, maxima are observed at sunrise (NH: 35 ± 5 pptv; SH: 47 ± 7 pptv), and minima at dusk (NH: 27 ± 5 pptv; SH: 35 ± 8 pptv). In both hemispheres, the daytime flux was directed from the atmosphere into the ocean, indicating that the ocean is a net sink for glyoxal during the day. After sunset the ocean was a source for glyoxal to the atmosphere (positive flux) in the SH; this primary ocean source was operative throughout the night. In the NH, the nighttime flux was positive only shortly after sunset and negative during most of the night. Positive EC fluxes of soluble glyoxal over oceans indicate the presence of an ocean surface organic microlayer (SML) and locate a glyoxal source within the SML. The origin of most atmospheric glyoxal, and possibly other oxygenated hydrocarbons over tropical oceans, remains unexplained and warrants further investigation.

On the Transition and Migration of Flight Functions in the Airspace System

NASA Technical Reports Server (NTRS)

Morris, Allan Terry; Young, Steve D.

2012-01-01

Since 400 BC, when man first replicated flying behavior with kites, up until the turn of the 20th century, when the Wright brothers performed the first successful powered human flight, flight functions have become available to man via significant support from man-made structures and devices. Over the past 100 years or so, technology has enabled several flight functions to migrate to automation and/or decision support systems. This migration continues with the United States NextGen and Europe s Single European Sky (a.k.a. SESAR) initiatives. These overhauls of the airspace system will be accomplished by accommodating the functional capabilities, benefits, and limitations of technology and automation together with the unique and sometimes overlapping functional capabilities, benefits, and limitations of humans. This paper will discuss how a safe and effective migration of any flight function must consider several interrelated issues, including, for example, shared situation awareness, and automation addiction, or over-reliance on automation. A long-term philosophical perspective is presented that considers all of these issues by primarily asking the following questions: How does one find an acceptable level of risk tolerance when allocating functions to automation versus humans? How does one measure or predict with confidence what the risks will be? These two questions and others will be considered from the two most-discussed paradigms involving the use of increasingly complex systems in the future: humans as operators and humans as monitors.

Does hyperthermia constrain flight duration in a short-distance migrant?

PubMed

Guillemette, Magella; Woakes, Anthony J; Larochelle, Jacques; Polymeropoulos, Elias T; Granbois, Jean-Marc; Butler, Patrick J; Pelletier, David; Frappell, Peter B; Portugal, Steven J

2016-09-26

While some migratory birds perform non-stop flights of over 11 000 km, many species only spend around 15% of the day in flight during migration, posing a question as to why flight times for many species are so short. Here, we test the idea that hyperthermia might constrain flight duration (FD) in a short-distance migrant using remote biologging technology to measure heart rate, hydrostatic pressure and body temperature in 19 migrating eider ducks (Somateria mollissima), a short-distance migrant. Our results reveal a stop-and-go migration strategy where migratory flights were frequent (14 flights day(-1)) and short (15.7 min), together with the fact that body temperature increases by 1°C, on average, during such flights, which equates to a rate of heat storage index (HSI) of 4°C h(-1) Furthermore, we could not find any evidence that short flights were limited by heart rate, together with the fact that the numerous stops could not be explained by the need to feed, as the frequency of dives and the time spent feeding were comparatively small during the migratory period. We thus conclude that hyperthermia appears to be the predominant determinant of the observed migration strategy, and suggest that such a physiological limitation to FD may also occur in other species.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. © 2016 The Author(s).

The limits of modifying migration speed to adjust to climate change

NASA Astrophysics Data System (ADS)

Schmaljohann, Heiko; Both, Christiaan

2017-08-01

Predicting the range of variation over which organisms can adjust to environmental change is a major challenge in ecology. This is exemplified in migratory birds which experience changes in different habitats throughout the annual cycle. Earlier studies showed European population trends declining strongest in migrant species with least adjustment in spring arrival time. Thus, the increasing mismatches with other trophic levels in seasonal breeding areas probably contribute to their large-scale decline. Here we quantify the potential range of adjusting spring arrival dates through modifying migration speeds by reviewing 49 tracking studies. Among-individual variation in migration speed was mainly determined by the relatively short stop-over duration. Assuming this population response reflects individual phenotypic plasticity, we calculated the potential for phenotypic plasticity to speed-up migration by reducing stop-over duration. Even a 50% reduction would lead to a mere two-day advance in arrival, considering adjustments on the final 2,000 km of the spring journey. Hence, in contrast to previous studies, flexibility in the major determinant of migration duration seems insufficient to adjust to ongoing climate change, and is unlikely to explain some of the observed arrival advancements in long-distance migrants.

Collective cell migration without proliferation: density determines cell velocity and wave velocity

NASA Astrophysics Data System (ADS)

Tlili, Sham; Gauquelin, Estelle; Li, Brigitte; Cardoso, Olivier; Ladoux, Benoît; Delanoë-Ayari, Hélène; Graner, François

2018-05-01

Collective cell migration contributes to embryogenesis, wound healing and tumour metastasis. Cell monolayer migration experiments help in understanding what determines the movement of cells far from the leading edge. Inhibiting cell proliferation limits cell density increase and prevents jamming; we observe long-duration migration and quantify space-time characteristics of the velocity profile over large length scales and time scales. Velocity waves propagate backwards and their frequency depends only on cell density at the moving front. Both cell average velocity and wave velocity increase linearly with the cell effective radius regardless of the distance to the front. Inhibiting lamellipodia decreases cell velocity while waves either disappear or have a lower frequency. Our model combines conservation laws, monolayer mechanical properties and a phenomenological coupling between strain and polarity: advancing cells pull on their followers, which then become polarized. With reasonable values of parameters, this model agrees with several of our experimental observations. Together, our experiments and model disantangle the respective contributions of active velocity and of proliferation in monolayer migration, explain how cells maintain their polarity far from the moving front, and highlight the importance of strain-polarity coupling and density in long-range information propagation.

Beyond Group-Threat: Temporal Dynamics of International Migration and Linkages to Anti-Foreigner Sentiment.

PubMed

DeWaard, Jack

2015-07-01

Prior research on the association between country-level patterns of international migration and anti-foreigner sentiment shows that larger foreign-born concentrations increase perceptions of threat among native-born individuals in receiving countries, which, in turn, give rise to exclusionary preferences. While recent work has assembled a list of limiting conditions that shape the strength of this association, I argue that these efforts are premature because they are based on a narrow way of conceptualising and measuring international migration. In contrast to concepts and measures privileging the size of the foreign-born population in receiving countries, I draw from other literatures highlighting the temporal dynamics of migration. In considering the role of the temporal dynamics of international migration in explaining variation in anti-foreigner sentiment, the question is whether and how the temporal stability of the foreign-born population in receiving countries matters. My results suggest that it does. The size and temporal stability of the foreign-born population play opposing roles in aggravating and ameliorating anti-foreigner sentiment, respectively, with each operating via different pathways at the individual level. My work thus breaks new ground by challenging existing theoretical constructs and operationalisations in the group-threat literature.

Internal and International Mobility as Adaptation to Climatic Variability in Contemporary Mexico: Evidence from the Integration of Census and Satellite Data.

PubMed

Leyk, Stefan; Runfola, Dan; Nawrotzki, Raphael J; Hunter, Lori M; Riosmena, Fernando

2017-08-01

Migration provides a strategy for rural Mexican households to cope with, or adapt to, weather events and climatic variability. Yet prior studies on "environmental migration" in this context have not examined the differences between choices of internal (domestic) or international movement. In addition, much of the prior work relied on very coarse spatial scales to operationalize the environmental variables such as rainfall patterns. To overcome these limitations, we use fine-grain rainfall estimates derived from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite. The rainfall estimates are combined with Population and Agricultural Census information to examine associations between environmental changes and municipal rates of internal and international migration 2005-2010. Our findings suggest that municipal-level rainfall deficits relative to historical levels are an important predictor of both international and internal migration, especially in areas dependent on seasonal rainfall for crop productivity. Although our findings do not contradict results of prior studies using coarse spatial resolution, they offer clearer results and a more spatially nuanced examination of migration as related to social and environmental vulnerability and thus higher degrees of confidence.

Migration of accreting giant planets

NASA Astrophysics Data System (ADS)

Crida, A.; Bitsch, B.; Raibaldi, A.

2016-12-01

We present the results of 2D hydro simulations of giant planets in proto-planetary discs, which accrete gas at a more or less high rate. First, starting from a solid core of 20 Earth masses, we show that as soon as the runaway accretion of gas turns on, the planet is saved from type I migration : the gap opening mass is reached before the planet is lost into its host star. Furthermore, gas accretion helps opening the gap in low mass discs. Consequently, if the accretion rate is limited to the disc supply, then the planet is already inside a gap and in type II migration. We further show that the type II migration of a Jupiter mass planet actually depends on its accretion rate. Only when the accretion is high do we retrieve the classical picture where no gas crosses the gap and the planet follows the disc spreading. These results impact our understanding of planet migration and planet population synthesis models. The e-poster presenting these results in French can be found here: L'e-poster présentant ces résultats en français est disponible à cette adresse: http://sf2a.eu/semaine-sf2a/2016/posterpdfs/156_179_49.pdf.

Beyond Group-Threat: Temporal Dynamics of International Migration and Linkages to Anti-Foreigner Sentiment

PubMed Central

DeWaard, Jack

2014-01-01

Prior research on the association between country-level patterns of international migration and anti-foreigner sentiment shows that larger foreign-born concentrations increase perceptions of threat among native-born individuals in receiving countries, which, in turn, give rise to exclusionary preferences. While recent work has assembled a list of limiting conditions that shape the strength of this association, I argue that these efforts are premature because they are based on a narrow way of conceptualising and measuring international migration. In contrast to concepts and measures privileging the size of the foreign-born population in receiving countries, I draw from other literatures highlighting the temporal dynamics of migration. In considering the role of the temporal dynamics of international migration in explaining variation in anti-foreigner sentiment, the question is whether and how the temporal stability of the foreign-born population in receiving countries matters. My results suggest that it does. The size and temporal stability of the foreign-born population play opposing roles in aggravating and ameliorating anti-foreigner sentiment, respectively, with each operating via different pathways at the individual level. My work thus breaks new ground by challenging existing theoretical constructs and operationalisations in the group-threat literature. PMID:26146481

Integration of nodal and BMP signals in the heart requires FoxH1 to create left-right differences in cell migration rates that direct cardiac asymmetry.

PubMed

Lenhart, Kari F; Holtzman, Nathalia G; Williams, Jessica R; Burdine, Rebecca D

2013-01-01

Failure to properly establish the left-right (L/R) axis is a major cause of congenital heart defects in humans, but how L/R patterning of the embryo leads to asymmetric cardiac morphogenesis is still unclear. We find that asymmetric Nodal signaling on the left and Bmp signaling act in parallel to establish zebrafish cardiac laterality by modulating cell migration velocities across the L/R axis. Moreover, we demonstrate that Nodal plays the crucial role in generating asymmetry in the heart and that Bmp signaling via Bmp4 is dispensable in the presence of asymmetric Nodal signaling. In addition, we identify a previously unappreciated role for the Nodal-transcription factor FoxH1 in mediating cell responsiveness to Bmp, further linking the control of these two pathways in the heart. The interplay between these TGFβ pathways is complex, with Nodal signaling potentially acting to limit the response to Bmp pathway activation and the dosage of Bmp signals being critical to limit migration rates. These findings have implications for understanding the complex genetic interactions that lead to congenital heart disease in humans.

Limited geographical origin and global spread of sulfadoxine-resistant dhps alleles in Plasmodium falciparum populations.

PubMed

Mita, Toshihiro; Venkatesan, Meera; Ohashi, Jun; Culleton, Richard; Takahashi, Nobuyuki; Tsukahara, Takahiro; Ndounga, Mathieu; Dysoley, Lek; Endo, Hiroyoshi; Hombhanje, Francis; Ferreira, Marcelo U; Plowe, Christopher V; Tanabe, Kazuyuki

2011-12-15

Plasmodium falciparum malaria resistant to chloroquine and pyrimethamine originated in limited foci and migrated to Africa. It remains unresolved whether P. falciparum resistance to sulfadoxine, which is conferred by mutations in dihydropteroate synthase (DHPS), evolved following a similar pattern. The dhps locus of 893 P. falciparum isolates from 12 countries in Asia, the Pacific Islands, Africa, and South America was sequenced. Haplotypes of 6 microsatellite loci flanking the dhps locus were determined to define the genetic relationships among sulfadoxine-resistant lineages. Six distinct sulfadoxine-resistant lineages were identified. Highly resistant lineages appear to have originated only in Southeast Asia and South America. Two resistant lineages found throughout Southeast Asia have been introduced to East Africa, where they appear to have spread. The infrequent selection of parasites highly resistant to sulfadoxine and the subsequent migration of resistant lineages from Asia to Africa are similar to the patterns observed in chloroquine and pyrimethamine resistance. These findings strongly suggest that the global migration of resistant parasites has played a decisive role in the establishment of drug-resistant P. falciparum parasites, and that similar patterns may be anticipated for the spread of artemisinin resistance.

Cell Migration During Heart Regeneration in Zebrafish

PubMed Central

Tahara, Naoyuki; Brush, Michael; Kawakami, Yasuhiko

2018-01-01

Zebrafish possess the remarkable ability to regenerate injured hearts as adults, which contrasts the very limited ability in mammals. Although very limited, mammalian hearts do in fact have measurable levels of cardiomyocyte regeneration. Therefore, elucidating mechanisms of zebrafish heart regeneration would provide information of naturally occurring regeneration to potentially apply to mammalian studies, in addition to addressing this biologically interesting phenomenon in itself. Studies over the past 13 years have identified processes and mechanisms of heart regeneration in zebrafish. After heart injury, preexisting cardiomyocytes dedifferentiate, enter the cell cycle, and repair the injured myocardium. This process requires interaction with epicardial cells, endocardial cells, and vascular endothelial cells. Epicardial cells envelope the heart, while endocardial cells make up the inner lining of the heart. They provide paracrine signals to cardiomyocytes to regenerate the injured myocardium, which is vascularized during heart regeneration. In addition, accumulating results suggest that local migration of these major cardiac cell types have roles in heart regeneration. In this review, we summarize the characteristics of various heart injury methods used in the research community and regeneration of the major cardiac cell types. Then, we discuss local migration of these cardiac cell types and immune cells during heart regeneration. PMID:27085002

[Strengthening health literacy of people with migration background: results of a qualitative evaluation].

PubMed

Horn, Annett; Vogt, Dominique; Messer, Melanie; Schaeffer, Doris

2015-06-01

The concept of "health literacy", which has gained attention in English-speaking countries during the last decade, is becoming increasingly popular in Germany. While studies on an international level indicate that people with migration background are often limited in their health literacy, there is a lack of empirical data on that topic in Germany. However, it is well known that they are exposed to health-related risks and problems comparatively often whereas they use health care services less frequently. This article focuses on the native speaking counseling services of the Independent Patient Counseling Germany (UPD gGmbH) as an example of good practice and introduces the results of the evaluation of this counseling service. Qualitative interviews were conducted with UPD-consultants as well as with users of the services. It became apparent that Turkish and Russian-speaking immigrants often have limited health-related literacy. Therefore, support and counseling services should focus not only on issues concerning language and cultural aspects. Furthermore, strategies strengthening the health literacy of persons with migration background are required. Therefore, instruments and strategies will be developed in cooperation with the UPD which aim to improve such skills of the UPD-consultants.

Ultra-high pressure LC for astaxanthin determination in shrimp by-products and active food packaging.

PubMed

Sanches-Silva, A; Ribeiro, T; Albuquerque, T G; Paseiro, P; Sendón, R; de Quirós, A Bernaldo; López-Cervantes, J; Sánchez-Machado, D I; Soto Valdez, H; Angulo, I; Aurrekoetxea, G P; Costa, H S

2013-06-01

Nowadays, there is increasing interest in natural antioxidants from food by-products. Astaxanthin is a potent antioxidant and one of the major carotenoids in crustaceans and salmonids. An ultra-high pressure liquid chromatographic method was developed and validated for the determination of astaxanthin in shrimp by-products, and its migration from new packaging materials to food simulants was also studied. The method uses an UPLC® BEH guard-column (2.1 × 5 mm, 1.7 µm particle size) and an UPLC® BEH analytical column (2.1 × 50 mm, 1.7 µm particle size). Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) acetonitrile-methanol (containing 0.05 m ammonium acetate)-dichloromethane (75:20:5, v/v/v) and (B) ultrapure water. This method was evaluated with respect to validation parameters such as linearity, precision, limit of detection, limit of quantification and recovery. Low-density polyethylene films were prepared with different amounts of the lipid fraction of fermented shrimp waste by extrusion, and migration was evaluated into food simulants (isooctane and ethanol 95%, v/v). Migration was not detected under the tested conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Whole-cell based solvent-free system for one-pot production of biodiesel from waste grease.

PubMed

Li, Aitao; Ngo, Thao P N; Yan, Jinyong; Tian, Kaiyuan; Li, Zhi

2012-06-01

A whole-cell based solvent-free system was developed for efficient conversion of waste grease to biodiesel via one-pot esterification and transesterification. By isolation and screening of lipase-producing strains from soil, Serratia marcescens YXJ-1002 was discovered for the biotransformation of grease to biodiesel. The lipase (SML) from this strain was cloned and expressed in Escherichia coli as an intracellular enzyme, showing 6 times higher whole-cell based hydrolysis activity than that of wild type strain. The recombinant cells were used for biodiesel production from waste grease in one-pot reactions containing no solvent with the addition of methanol in several small portions, and 97% yield of biodiesel (FAME) was achieved under optimized conditions. In addition, the whole-cell biocatalysts showed excellent reusability, retaining 74% productivity after 4 cycles. The developed system, biocatalyst, and process enable the efficient, low-cost, and green production of biodiesel from waste grease, providing with a potential industrial application. Copyright © 2012 Elsevier Ltd. All rights reserved.

Catchment-scale evaluation of pollution potential of urban snow at two residential catchments in southern Finland.

PubMed

Sillanpää, Nora; Koivusalo, Harri

2013-01-01

Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with continuous runoff measurements. The results of the snow quality were used to produce catchment-scale estimates of areal snow mass loads (SML). Based on the results, urbanization reduced areal snow water equivalent but increased pollutant accumulation in snow: SMLs in a medium-density residential catchment were two- to four-fold higher in comparison with a low-density residential catchment. The main sources of pollutants were related to vehicular traffic and road maintenance, but also pet excrement increased concentrations to a high level. Ploughed snow can contain 50% of the areal pollutant mass stored in snow despite its small surface area within a catchment.

Automatic Selection of Order Parameters in the Analysis of Large Scale Molecular Dynamics Simulations.

PubMed

Sultan, Mohammad M; Kiss, Gert; Shukla, Diwakar; Pande, Vijay S

2014-12-09

Given the large number of crystal structures and NMR ensembles that have been solved to date, classical molecular dynamics (MD) simulations have become powerful tools in the atomistic study of the kinetics and thermodynamics of biomolecular systems on ever increasing time scales. By virtue of the high-dimensional conformational state space that is explored, the interpretation of large-scale simulations faces difficulties not unlike those in the big data community. We address this challenge by introducing a method called clustering based feature selection (CB-FS) that employs a posterior analysis approach. It combines supervised machine learning (SML) and feature selection with Markov state models to automatically identify the relevant degrees of freedom that separate conformational states. We highlight the utility of the method in the evaluation of large-scale simulations and show that it can be used for the rapid and automated identification of relevant order parameters involved in the functional transitions of two exemplary cell-signaling proteins central to human disease states.

Modeling and predictions of biphasic mechanosensitive cell migration altered by cell-intrinsic properties and matrix confinement.

PubMed

Pathak, Amit

2018-04-12

Motile cells sense the stiffness of their extracellular matrix (ECM) through adhesions and respond by modulating the generated forces, which in turn lead to varying mechanosensitive migration phenotypes. Through modeling and experiments, cell migration speed is known to vary with matrix stiffness in a biphasic manner, with optimal motility at an intermediate stiffness. Here, we present a two-dimensional cell model defined by nodes and elements, integrated with subcellular modeling components corresponding to mechanotransductive adhesion formation, force generation, protrusions and node displacement. On 2D matrices, our calculations reproduce the classic biphasic dependence of migration speed on matrix stiffness and predict that cell types with higher force-generating ability do not slow down on very stiff matrices, thus disabling the biphasic response. We also predict that cell types defined by lower number of total receptors require stiffer matrices for optimal motility, which also limits the biphasic response. For a cell type with robust biphasic migration on 2D surface, simulations in channel-like confined environments of varying width and height predict faster migration in more confined matrices. Simulations performed in shallower channels predict that the biphasic mechanosensitive cell migration response is more robust on 2D micro-patterns as compared to the channel-like 3D confinement. Thus, variations in the dimensionality of matrix confinement alters the way migratory cells sense and respond to the matrix stiffness. Our calculations reveal new phenotypes of stiffness- and topography-sensitive cell migration that critically depend on both cell-intrinsic and matrix properties. These predictions may inform our understanding of various mechanosensitive modes of cell motility that could enable tumor invasion through topographically heterogeneous microenvironments. © 2018 IOP Publishing Ltd.

Inferring genetic connectivity in real populations, exemplified by coastal and oceanic Atlantic cod.

PubMed

Spies, Ingrid; Hauser, Lorenz; Jorde, Per Erik; Knutsen, Halvor; Punt, André E; Rogers, Lauren A; Stenseth, Nils Chr

2018-05-08

Genetic data are commonly used to estimate connectivity between putative populations, but translating them to demographic dispersal rates is complicated. Theoretical equations that infer a migration rate based on the genetic estimator F ST , such as Wright's equation, F ST ≈ 1/(4 N e m + 1), make assumptions that do not apply to most real populations. How complexities inherent to real populations affect migration was exemplified by Atlantic cod in the North Sea and Skagerrak and was examined within an age-structured model that incorporated genetic markers. Migration was determined under various scenarios by varying the number of simulated migrants until the mean simulated level of genetic differentiation matched a fixed level of genetic differentiation equal to empirical estimates. Parameters that decreased the N e / N t ratio (where N e is the effective and N t is the total population size), such as high fishing mortality and high fishing gear selectivity, increased the number of migrants required to achieve empirical levels of genetic differentiation. Higher maturity-at-age and lower selectivity increased N e / N t and decreased migration when genetic differentiation was fixed. Changes in natural mortality, fishing gear selectivity, and maturity-at-age within expected limits had a moderate effect on migration when genetic differentiation was held constant. Changes in population size had the greatest effect on the number of migrants to achieve fixed levels of F ST , particularly when genetic differentiation was low, F ST ≈ 10 -3 Highly variable migration patterns, compared with constant migration, resulted in higher variance in genetic differentiation and higher extreme values. Results are compared with and provide insight into the use of theoretical equations to estimate migration among real populations. Copyright © 2018 the Author(s). Published by PNAS.

Labour migration and rural transformation in post-colonial Swaziland.

PubMed

Simelane, H S

1995-07-01

This article describes the effects of labor migration in rural southern Swaziland. It is argued that wages from rural migration to mining areas were invested in agricultural implements such as tractors, in education of children, and in cattle. These effects are improvements in rural quality of life and involve women in agricultural production. Male labor migration in southern Swaziland contributed to progress and rural development for rich and poor families at the individual level. Community level changes from labor migration were not evident. The author does not suggest that all changes were due to labor migration or unique. Negative effects are recognized, such as life style changes or changes in social customs. It is stated that southern Swaziland benefited little post-independence from national development. The Lowveld benefitted from sugar and citrus plantations. The central region experienced development of industry and commerce. The northern region had sugar plantations and mining development. The western region established commercial forests. The south only had export labor, which was attracted to higher wages in South Africa. Data and arguments in this article pertain only to male labor migration to mining areas. The literature on development tends to associate male labor migration with underdevelopment. Women are left to plough the fields in traditional agricultural production. Evidence is presented for southern Swaziland, which showed periods of low agricultural production and poor health conditions. During the 1940s this was the case and male absence was very high. Although women had limitations, it is argued that the most important factor was unavailability of new technology. By the 1970s, women were able to hire private or government tractors for tilling the soil.

UG311, An Oncofetal Marker Lost with Prostate Cancer Progression

DTIC Science & Technology

2001-04-01

CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT Unclassified Unclassified...that the IGF2R facilitates the degradation of IGF-2 by transporting IGF-2 to lysozomes, thereby limiting the signal potentiated by the growth factor...integrin mediated migration. IGF-1 had no effect on this activity. IGFBP-1 is expressed in the placenta [105] where it may limit trophoblast invasion

Migration of refugees and non-refugees to Amman, 1948-1977.

PubMed

Samha, M

1980-12-01

The migration to the city of Amman, Jordan during periods of war and peace over the past 3 decades was studied in an attempt to discover patterns of migration to Amman, to better understand their nature, to determine the constraints of migration, and to discover its motivation by resorting in part to classification and in part to analysis. The data were derived from a household survey of the amman population that covered 1750 randomly selected households and was conducted in 1977. The study was confined to compulsory migration resulting from the events in Palestine in 1948 and from the occupation of the West Bank of Jordan in 1965 and to voluntary internal migration arising from the lack of equal social and economic opportunities in different parts of the country. The 1977 survey, which covered 1355 households that had migrated to Amman, revealed that 703 were refugee households, representing the equivalent of 52% of all migrant households. The occupation of Palestine in 1948 led to a sharp influx of refugees to Amman with refugees making up 34.4% of the total number of migrants to Amman. In 1967 refugees from Gaza and the West Bank constituted 59.2% of the total number of migrants to Amman. Around 23% of all refugees are refugees for the 2nd time. Most of the refugees went directly to Amman with only a small minority (14%) moving to the city in stages, and most of these were 1948 refugees. The size and trend of migration to Amman was linked to a great extent, to the movement of refugees, which represented more than 1/2 of the migration to the city. The occupation of Palestine in 1948 led to the concentration of economic activities in the East Bank of Jordan. This meant migration east as far as the refugees from occupied Palestine and the migrants from the West Bank were concerned. As a consequence, Amman became the major attraction. The sample icluded 532 households that had migrated internally to Amman. It represented the voluntary migration to Amman from the West Bank. More households migrated from the West Bank than from the East Bank until 1967. Following occupation, migration from the West Bank dropped, and internal migration from the East Bank to the city became dominant. The scarcity of economic opportunities in most of the other Jordanian cities markedly limited the possibility that migrants would move in stages. Migration for employment reasons accounted for 31% of the households that moved to Amman, and better working opportunities accounted for the migration of 30%. Another 21% moved because the head of the household was seeking employment.

Couple Relationship Standards and Migration: Comparing Hong Kong Chinese with Australian Chinese.

PubMed

Halford, W Kim; Leung, Patrick; Hung-Cheung, Chan; Chau-Wan, Lau; Hiew, Danika; van de Vijver, Fons J R

2017-12-14

Rates of international migration are increasing, which raises the question of how migration might influence couple relationship standards and impact on the standards of migrants forming intercultural relationships. We compared relationship standards in n = 286 Chinese living in Hong Kong, China, with standards in n = 401 Chinese migrants to a Western country (Australia) by administering the Chinese-Western Intercultural Couple Standards Scale (CWICSS). We also compared these two groups to n = 312 Westerners living in Australia. We first tested the structural invariance of the CWICSS across the three samples with a multigroup confirmatory factor analysis. There was marginal but acceptable fit of a model of two positively correlated latent factors: Couple Bond (with four indicators, such as demonstration of love and caring) and Family Responsibility (also with four indicators, such as extended family relations and preserving face). Within the limitations of the study, results suggest migration is associated predominantly with differences in women's, but not men's, relationship standards. Migrant Chinese women show alignment of Couple Bond standards with Western standards, and divergence of Family Responsibility standards from Western standards. Discussion focused on how migration and intercultural relationship experiences might differentially influence various domains of relationship standards, gender differences in migration effects on standards, and the implications for working with culturally diverse couples. © 2017 Family Process Institute.

Migration and common mental disorder: an improvement in mental health over time?

PubMed

Butler, Margaret; Warfa, Nasir; Khatib, Yasmin; Bhui, Kamaldeep

2015-02-01

Global migration is reaching record high levels and UK migrant groups comprise an increasing proportion of the total population. The migratory process causes stress that can affect mental health. There is limited consistent empirical evidence of a longitudinal nature to explain the association between migration and mental health. This review aims to examine the evidence of a relationship between migration and common mental disorder (CMD) amongst migrants over time. A comprehensive search of medical and psychiatric databases for global quantitative empirical studies investigating incidence of CMD amongst adult migrants from 1975 to July 2012 was conducted. Declines in rates of CMD amongst migrants over time were reported by two thirds of the 18 studies reviewed, less than one third of which were statistically significant. On the contrary, three studies showed an increased rate of CMD, one statistically significant. Individual psychological resources, social support, the acculturation process, cultural variations and time since relocation are identified as statistically significant protective factors against the development of CMD amongst migrants. New enlightening points include the significant impact of varying patterns of psychological distress, of which negative is the most adverse for CMD. Migration is an extremely complex process. Further clarification is needed to gain deeper understanding of the relationship between migration and CMD to address contradictions in the literature and health inequalities amongst migrants.

Evaluation of migration models that might be used in support of regulations for food-contact plastics.

PubMed

Begley, T; Castle, L; Feigenbaum, A; Franz, R; Hinrichs, K; Lickly, T; Mercea, P; Milana, M; O'Brien, A; Rebre, S; Rijk, R; Piringer, O

2005-01-01

Materials and articles intended to come into contact with food must be shown to be safe because they might interact with food during processing, storage and the transportation of foodstuffs. Framework Directive 89/109/EEC and its related specific Directives provide this safety basis for the protection of the consumer against inadmissible chemical contamination from food-contact materials. Recently, the European Commission charged an international group of experts to demonstrate that migration modelling can be regarded as a valid and reliable tool to calculate 'reasonable worst-case' migration rates from the most important food-contact plastics into the European Union official food simulants. The paper summarizes the main steps followed to build up and validate a migration estimation model that can be used, for a series of plastic food-contact materials and migrants, for regulatory purposes. Analytical solutions of the diffusion equation in conjunction with an 'upper limit' equation for the migrant diffusion coefficient, D(P), and the use of 'worst case' partitioning coefficients K(P,F) were used in the migration model. The results obtained were then validated, at a confidence level of 95%, by comparison with the available experimental evidence. The successful accomplishment of the goals of this project is reflected by the fact that in Directive 2002/72/EC, the European Commission included the mathematical modelling as an alternative tool to determine migration rates for compliance purposes.

A framework for understanding semi-permeable barrier effects on migratory ungulates

USGS Publications Warehouse

Sawyer, Hall; Kauffman, Matthew J.; Middleton, Arthur D.; Morrison, Thomas A.; Nielson, Ryan M.; Wyckoff, Teal B.

2013-01-01

1. Impermeable barriers to migration can greatly constrain the set of possible routes and ranges used by migrating animals. For ungulates, however, many forms of development are semi-permeable, and making informed management decisions about their potential impacts to the persistence of migration routes is difficult because our knowledge of how semi-permeable barriers affect migratory behaviour and function is limited. 2. Here, we propose a general framework to advance the understanding of barrier effects on ungulate migration by emphasizing the need to (i) quantify potential barriers in terms that allow behavioural thresholds to be considered, (ii) identify and measure behavioural responses to semi-permeable barriers and (iii) consider the functional attributes of the migratory landscape (e.g. stopovers) and how the benefits of migration might be reduced by behavioural changes. 3. We used global position system (GPS) data collected from two subpopulations of mule deer Odocoileus hemionus to evaluate how different levels of gas development influenced migratory behaviour, including movement rates and stopover use at the individual level, and intensity of use and width of migration route at the population level. We then characterized the functional landscape of migration routes as either stopover habitat or movement corridors and examined how the observed behavioural changes affected the functionality of the migration route in terms of stopover use. 4. We found migratory behaviour to vary with development intensity. Our results suggest that mule deer can migrate through moderate levels of development without any noticeable effects on migratory behaviour. However, in areas with more intensive development, animals often detoured from established routes, increased their rate of movement and reduced stopover use, while the overall use and width of migration routes decreased. 5. Synthesis and applications. In contrast to impermeable barriers that impede animal movement, semi-permeable barriers allow animals to maintain connectivity between their seasonal ranges. Our results identify the mechanisms (e.g. detouring, increased movement rates, reduced stopover use) by which semi-permeable barriers affect the functionality of ungulate migration routes and emphasize that the management of semi-permeable barriers may play a key role in the conservation of migratory ungulate populations.

The use of a Phosphate-Based Migrating Corrosion Inhibitor to Repair Reinforced Concrete Elements Contaminated by Chlorides

NASA Astrophysics Data System (ADS)

Tittarelli, Francesca; Mobili, Alessandra; Bellezze, Tiziano

2017-08-01

The use of sodium monofluorophosphate (MFP) was experimented as migrator inhibiting treatment against corrosion of reinforced concrete elements induced by chlorides. The results show that sodium monofluorophosphate, applied by surface impregnation, is able to slow down reinforcement corrosion only for reinforcing steel bars with concrete cover not thicker than 1 cm. This limitation is most probably due to the difficulty, with the type of application adopted, in making MFP to reach concentrations high enough to inhibit the corrosive process at greater depths from the impregnation surface.

Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy

NASA Astrophysics Data System (ADS)

Guo, Zhi; Wan, Yan; Yang, Mengjin; Snaider, Jordan; Zhu, Kai; Huang, Libai

2017-04-01

The Shockley-Queisser limit for solar cell efficiency can be overcome if hot carriers can be harvested before they thermalize. Recently, carrier cooling time up to 100 picoseconds was observed in hybrid perovskites, but it is unclear whether these long-lived hot carriers can migrate long distance for efficient collection. We report direct visualization of hot-carrier migration in methylammonium lead iodide (CH3NH3PbI3) thin films by ultrafast transient absorption microscopy, demonstrating three distinct transport regimes. Quasiballistic transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers transport distance that could overcome grain boundaries. The nonequilibrium transport persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport limit. These results suggest potential applications of hot-carrier devices based on hybrid perovskites.

Epoxidized soy bean oil migrating from the gaskets of lids into food packed in glass jars. Analysis by on-line liquid chromatography-gas chromatography.

PubMed

Fankhauser-Noti, Anja; Fiselier, Katell; Biedermann-Brem, Sandra; Grob, Koni

2005-08-05

The migration of epoxidized soy bean oil (ESBO) from the gasket in the lids of glass jars into foods, particularly those rich in edible oil, often far exceeds the legal limit (60 mg/kg). ESBO was determined through a methyl ester isomer of diepoxy linoleic acid. Transesterification occurred directly in the homogenized food. From the extracted methyl esters, the diepoxy components were isolated by normal-phase LC and transferred on-line to gas chromatography with flame ionization detection using the on-column interface in the concurrent solvent evaporation mode. The method involves verification elements to ensure the reliability of the results for every sample analyzed. The detection limit is 2-5 mg/kg, depending on the food. Uncertainty of the procedure is below 10%.

Age of Migration Life Expectancy with Functional Limitations and Morbidity in Mexican Americans.

PubMed

Garcia, Marc A; Valderrama-Hinds, Luis M; Chiu, Chi-Tsun; Mutambudzi, Miriam S; Chen, Nai-Wei; Raji, Mukaila

2017-07-01

The U.S. Mexican American population enjoys longer life expectancies relative to other racial/ethnic groups but is disproportionately affected by chronic conditions and functional limitations. Studying the impact of heterogeneity in age, time and other characteristics of migration among older Mexican Americans can inform our understanding of health disparities and healthcare needs in later-life. This research used 20 years of data from the Hispanic Established Populations for the Epidemiologic Study of the Elderly to assess the proportion of life spent with functional limitations and one or more morbidity (according to age of migration and sex) in the U.S. Mexican-American population. The results indicate that early-life and late-life migrant women spend more years with Performance-Oriented Mobility Assessment limitations than U.S.-born women. Conversely, midlife migrant women were not statistically different from U.S.-born women in years spent disabled. In men, midlife migrants had longer life expectancies and had more disability-free years than U.S.-born men. For morbidity, late-life migrant women spent a significantly smaller proportion of their elderly years with morbidity than U.S.-born women, but late-life migrant men spent more years with morbidity than U.S.-born men. These findings illustrate that older Mexican Americans in the United States are heterogeneous in nativity and health outcomes. More years spent disabled or unhealthy may result in greater burden on family members and greater dependence on public resources. These findings have implications for the development of social and health policies to appropriately target the medical conditions and disabilities of older Mexican Americans entering late life. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

Engendering climate change-induced migration

NASA Astrophysics Data System (ADS)

Caretta, Martina Angela; Miletto, Michela

2017-04-01

Climate change leads to increased climate variability, which is manifest in extreme weather events such as floods and droughts. These put at stake agricultural productivity, forestry, inland fisheries, aquaculture, water supply and sanitation which in turn hamper poorest householdś self-sufficiency and capability to cope with risks. Due to the risk of losing or the actual loss of livelihood, farmers in the Global South must look for alternative strategies to diversify risk. Migration is one of those strategies, which that can be seen either as an adaptive measure or an indicator of limits to adaptation to environmental stress. 60% of young migrants live in the Global South (UN, 2013). Many internally displaced people in the world are under the age of 18, some move with their families, other, mostly in South Asia and West Africa, migrate alone. Youth, as all migrants, are seeking better economic opportunities to support themselves and their families. Migration is a gendered process which plays out differently in diverse societies depending on local cultural norms that do not only affect and are affected by gender roles, but also by age, class and ethnicity. Threats to water availability, access and water hazards have diverse impacts on men and women. The link gender and climate-induced migration is still under investigation and few studies provide concrete country specific examples of this phenomenon. Our paper will present a state of the art literature review around climate-induced migration in the Global South from a gender perspective showing how meńs and womeńs migratory decisions, patterns and outcomes differ at the stage pre-during post migration.

When and where does mortality occur in migratory birds? Direct evidence from long-term satellite tracking of raptors.

PubMed

Klaassen, Raymond H G; Hake, Mikael; Strandberg, Roine; Koks, Ben J; Trierweiler, Christiane; Exo, Klaus-Michael; Bairlein, Franz; Alerstam, Thomas

2014-01-01

Information about when and where animals die is important to understand population regulation. In migratory animals, mortality might occur not only during the stationary periods (e.g. breeding and wintering) but also during the migration seasons. However, the relative importance of population limiting factors during different periods of the year remains poorly understood, and previous studies mainly relied on indirect evidence. Here, we provide direct evidence about when and where migrants die by identifying cases of confirmed and probable deaths in three species of long-distance migratory raptors tracked by satellite telemetry. We show that mortality rate was about six times higher during migration seasons than during stationary periods. However, total mortality was surprisingly similar between periods, which can be explained by the fact that risky migration periods are shorter than safer stationary periods. Nevertheless, more than half of the annual mortality occurred during migration. We also found spatiotemporal patterns in mortality: spring mortality occurred mainly in Africa in association with the crossing of the Sahara desert, while most mortality during autumn took place in Europe. Our results strongly suggest that events during the migration seasons have an important impact on the population dynamics of long-distance migrants. We speculate that mortality during spring migration may account for short-term annual variation in survival and population sizes, while mortality during autumn migration may be more important for long-term population regulation (through density-dependent effects). © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

UPLC-ESI-Q-TOF-MS(E) and GC-MS identification and quantification of non-intentionally added substances coming from biodegradable food packaging.

PubMed

Canellas, Elena; Vera, Paula; Nerín, Cristina

2015-09-01

Biodegradable packagings are made by combination of several materials creating a multilayer with the properties needed. Each material, including the adhesive, could contain substances that could migrate to the food. In this work, gas chromatography coupled with mass spectrometry and ultra-high-pressure liquid chromatography coupled with quadrupole time-of-flight mass spectrometry were used to identify the biodegradable adhesive compounds. Five of the 13 compounds identified were nonintentionally added substances; they were neoformed compounds created by the reaction of added compounds in the adhesive. Moreover, the migration of the compounds through four different biodegradable materials-paper, polylactic acid, ecovio®, and polyvinyl alcohol-was studied for the first time. Three of the 13 compounds identified in the adhesive migrated from the adhesive to Tenax®, which was used as a solid food simulant. One of them, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, was an intentionally added substance, and the other two were 1,6-dioxacyclododecane-7,12-dione and 1,6,13,18-tetraoxacyclotetracosane-7,12,19,24-tetraone, which were nonintentionally added substances identified in this work. Higher migration values (ranging from 0.81 to 2.07 mg/kg) were observed for migration through ecovio® than through the multilayer made by combination of ecovio® and polyvinyl alcohol (0.07-0.39 mg/kg) owing to the barrier effect provided by polyvinyl alcohol. The migration values for migration through paper and polylactic acid were below the limits of detection.

Migration of bisphenol A from plastic baby bottles, baby bottle liners and reusable polycarbonate drinking bottles.

PubMed

Kubwabo, C; Kosarac, I; Stewart, B; Gauthier, B R; Lalonde, K; Lalonde, P J

2009-06-01

Human exposure to bisphenol A (BPA) has recently received special attention. It has been shown that exposure to BPA may occur through the consumption of beverages or foods that have been in contact with polycarbonate (PC) plastic containers or epoxy resins in food packaging. A BPA migration study was conducted using a variety of plastic containers, including polycarbonate baby bottles, non-PC baby bottles, baby bottle liners, and reusable PC drinking bottles. Water was used to simulate migration into aqueous and acidic foods; 10% ethanol solution to simulate migration to low- and high-alcoholic foods; and 50% ethanol solution to simulate migration to fatty foods. By combining solid-phase extraction, BPA derivatization and analysis by GC-EI/MS/MS, a very low detection limit at the ng l(-1) level was obtained. Migration of BPA at 40 degrees C ranged from 0.11 microg l(-1) in water incubated for 8 h to 2.39 microg l(-1) in 50% ethanol incubated for 240 h. Residual BPA leaching from PC bottles increased with temperature and incubation time. In comparison with the migration observed from PC bottles, non-PC baby bottles and baby bottle liners showed only trace levels of BPA. Tests for leachable lead and cadmium were also conducted on glass baby bottles since these represent a potential alternative to plastic bottles. No detectable lead or cadmium was found to leach from the glass. This study indicated that non-PC plastic baby bottles, baby bottle liners and glass baby bottles might be good alternatives for polycarbonate bottles.

Modeling Studies to Constrain Fluid and Gas Migration Associated with Hydraulic Fracturing Operations

NASA Astrophysics Data System (ADS)

Rajaram, H.; Birdsell, D.; Lackey, G.; Karra, S.; Viswanathan, H. S.; Dempsey, D.

2015-12-01

The dramatic increase in the extraction of unconventional oil and gas resources using horizontal wells and hydraulic fracturing (fracking) technologies has raised concerns about potential environmental impacts. Large volumes of hydraulic fracturing fluids are injected during fracking. Incidents of stray gas occurrence in shallow aquifers overlying shale gas reservoirs have been reported; whether these are in any way related to fracking continues to be debated. Computational models serve as useful tools for evaluating potential environmental impacts. We present modeling studies of hydraulic fracturing fluid and gas migration during the various stages of well operation, production, and subsequent plugging. The fluid migration models account for overpressure in the gas reservoir, density contrast between injected fluids and brine, imbibition into partially saturated shale, and well operations. Our results highlight the importance of representing the different stages of well operation consistently. Most importantly, well suction and imbibition both play a significant role in limiting upward migration of injected fluids, even in the presence of permeable connecting pathways. In an overall assessment, our fluid migration simulations suggest very low risk to groundwater aquifers when the vertical separation from a shale gas reservoir is of the order of 1000' or more. Multi-phase models of gas migration were developed to couple flow and transport in compromised wellbores and subsurface formations. These models are useful for evaluating both short-term and long-term scenarios of stray methane release. We present simulation results to evaluate mechanisms controlling stray gas migration, and explore relationships between bradenhead pressures and the likelihood of methane release and transport.

Impact, regulation and health policy implications of physician migration in OECD countries

PubMed Central

Forcier, Mélanie Bourassa; Simoens, Steven; Giuffrida, Antonio

2004-01-01

Background In the face of rising demand for medical services due to ageing populations, physician migration flows are increasingly affecting the supply of physicians in Organisation for Economic Co-operation and development (OECD) countries. This paper offers an integrated perspective on the impact of physician migration on home and host countries and discusses international regulation and policy approaches governing physician migration. Methods Information about migration flows, international regulation and policies governing physician migration were derived from two questionnaires sent to OECD countries, a secondary analysis of EUROSTAT Labour Force Surveys, a literature review and official policy documents of OECD countries. Results OECD countries increasingly perceive immigration of foreign physicians as a way of sustaining their physician workforce. As a result, countries have entered into international agreements regulating physician migration, although their success has been limited due to the imposition of licensing requirements and the protection of vested interests by domestic physicians. OECD countries have therefore adopted specific policies designed to stimulate the immigration of foreign physicians, whilst minimising its negative impact on the home country. Measures promoting immigration have included international recruitment campaigns, less strict immigration requirements and arrangements that foster shared learning between health care systems. Policies restricting the societal costs of physician emigration from developing countries such as good practice guidelines and taxes on host countries have not yet produced their expected effect or in some cases have not been established at all. Conclusions Although OECD countries generally favour long-term policies of national self-sufficiency to sustain their physician workforce, such policies usually co-exist with short-term or medium-term policies to attract foreign physicians. As this is likely to continue, there is a need to create a global framework that enforces physician migration policies that confer benefits on home and host countries. In the long term, OECD countries need to put in place appropriate education and training policies rather than rely on physician migration to address their future needs. PMID:15257752

Politics and ideology in migration policy formulation: the case of Kuwait.

PubMed

Russell, S S

1989-01-01

In 1716, 3 prominent families of the original Kuwaitis agreed that 1 family would control finance and commerce, another seafaring activities, and the 3rd the government. This continued allegiance has been instrumental in shaping migration policy in Kuwait. Migration to Kuwait began in the 1930s-1940s to meet labor needs of the oil industry and the social infrastructure. This began a steady increase, with several setbacks in the early 1970s, of the migrant population. Between (1959-1964), Kuwait had to determine how it would exist and operate as an independent state. The new state established migration policy based on a need for national identity and on weighing the interests of 4 political groups: the ruling family; the wealthy merchants; the Arab Nationalist Movement; and Kuwaiti Nationalists. 3 migration laws emerged which satisfied the 4 groups and in some form continued into the 1980s. These laws basically allowed the continuation of free immigration of labor with the government controlling entry, movement, rights, and employment of the migrants while stressing neutrality and reciprocity with other states, especially Arab states. 1 law greatly limited the number of citizenships to nonKuwaitis and guaranteed economic control and major share of profits to Kuwaitis. Between 1965-1984, many changes to migration policy occurred for political, demographic, and economic reasons. 1 such change was an amendment restricting naturalization to Muslims, thereby not allowing naturalization of the growing Asian migration population, to preserve their cultural authenticity. By 1984, following 1 rebalance of the distribution of Kuwaitis and nonKuwaitis, economic declines, and security threats, migration policy shifted back to population balance. Kuwaiti history shows, however, that experimenting with migration policy and population balance cannot establish internal political and social cohesion. This is a revised version of a paper originally presented at the 1987 Annual Meeting of the Population Association of America (see Population Index, Vol. 53, No. 3, Fall 1987, p. 409).

Using sutures to attach miniature tracking tags to small bats for multimonth movement and behavioral studies

Treesearch

Kevin T. Castle; Ted Weller; Paul M. Cryan; Cris D. Hein; Michael R. Schirmacher

2015-01-01

Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (<30 g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration, particularly in the context of emerging...

Understanding the rural population migration pattern of Uttarakhand using Geophysical, Geological and Socio-Economical BigData

NASA Astrophysics Data System (ADS)

Chattopadhyay, Kausik; Chattopadhyay, Pallavi

2017-04-01

Uttarakhand, a Himalayan state of India is facing a worst scenario of rural population migration for the past few decades from hill regions to the planes. While urbanization is believed to be one of the major factors for migration, how geo scientific parameters can impact the population to redraw the demographies of the hills is studied in this research. An attempt is made using density based clustering and Apriori association rule mining on 45 derived variables with a time series of 30 years to understand the rural population migration pattern. Both zone identification and origin-destination pair extraction are formulated as spatial-temporal point clustering problem and DBSCAN (Density-Based Spatial Clustering of Applications with Noise) is applied to solve them. Specifically the population migration is formulated as a 4D point clustering problem and the relative distance between two origin - destination pair with a preference factor is used to fine tune the cluster length. In Apriori, threshold values for confidence and J-measure are kept same as for rule extraction. Rules with maximum confidence level and J-measure are obtained for an antecedent window of 18 months, consequent window of 4 months and time lag of 2 months. From the rules extracted, it can be demonstrated that almost all the geoscience indices are occurring as antecedents for migration episodes. The result demonstrates that the three districts that have registered the highest migration rates are also the districts that have witnessed maximum depletion in water sources. Even though some districts have higher number of landslide incidents, their out migration is less compared to other hill districts. However districts experiencing higher number of earthquakes are experiencing higher out migration. Upper hill region with higher precipitation experience higher migration compared to their lower hill counterpart. However this is not true when compared to the counter parts in the plane regions. Even though temperature fluctuation results in seasonal out migration, it does not have any long term impact. Resource and logistical constraints limit the frequency and extent of observations, necessitating the development of a systematic computational framework that objectively represents environmental variability at the desired spatial scale and such comprehensive big data model can be instrumental in arresting the rural migration which has been posing major threat to the livelihood of this Himalayan state.