How well do satellite observations and models capture diurnal variation in aerosols over the Korean Peninsula?

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Xian, P.; Campbell, J. R.

2016-12-01

Aerosol sources, sinks, and transport processes have important variations over the diurnal cycle. Advances in geostationary satellite observation have made it possible to retrieve aerosol properties over a larger fraction of the diurnal cycle in many areas. However, the conditions for retrieval of aerosol from space also have systematic diurnal variation, which must be considered when interpreting satellite data. We used surface PM2.5 observations from the Korean National Institute for Environmental Research, together with the dense network of AERONET sun photometers deployed in Korea for the KORUS-AQ mission in spring 2016, to examine diurnal variations in aerosol conditions and quantify the effect of systematic diurnal processes on daily integrated aerosol quantities of forcing and PM2.5 24-hour exposure. Time-resolved observations of aerosols from in situ data were compared to polar and geostationary satellite observations to evaluate these questions: 1) How well is diurnal variation observed in situ captured by satellite products? 2) Do the satellite products show evidence of systematic biases related to diurnally varying observing conditions? 3) What is the implication of diurnal variation for aerosol forcing estimates based on observations near solar noon? The diurnal variation diagnosed from observations was also compared to the output of the Navy Aerosol Analysis and Prediction System (NAAPS), to examine the ability of this model to capture aerosol diurnal variation. Finally, we discuss the implications of the observed diurnal variation for assimilation of aerosol observations into forecast models.

Using Space Lidar Observations to Decompose Longwave Cloud Radiative Effect Variations Over the Last Decade

NASA Astrophysics Data System (ADS)

Vaillant de Guélis, Thibault; Chepfer, Hélène; Noel, Vincent; Guzman, Rodrigo; Winker, David M.; Plougonven, Riwal

2017-12-01

Measurements of the longwave cloud radiative effect (LWCRE) at the top of the atmosphere assess the contribution of clouds to the Earth warming but do not quantify the cloud property variations that are responsible for the LWCRE variations. The CALIPSO space lidar observes directly the detailed profile of cloud, cloud opacity, and cloud cover. Here we use these observations to quantify the influence of cloud properties on the variations of the LWCRE observed between 2008 and 2015 in the tropics and at global scale. At global scale, the method proposed here gives good results except over the Southern Ocean. We find that the global LWCRE variations observed over ocean are mostly due to variations in the opaque cloud properties (82%); transparent cloud columns contributed 18%. Variation of opaque cloud cover is the first contributor to the LWCRE evolution (58%); opaque cloud temperature is the second contributor (28%).

Long-term variations of the upper atmosphere parameters on Rome ionosonde observations and their interpretation

NASA Astrophysics Data System (ADS)

Perrone, Loredana; Mikhailov, Andrey; Cesaroni, Claudio; Alfonsi, Lucilla; Santis, Angelo De; Pezzopane, Michael; Scotto, Carlo

2017-09-01

A recently proposed self-consistent approach to the analysis of thermospheric and ionospheric long-term trends has been applied to Rome ionosonde summer noontime observations for the (1957-2015) period. This approach includes: (i) a method to extract ionospheric parameter long-term variations; (ii) a method to retrieve from observed foF1 neutral composition (O, O2, N2), exospheric temperature, Tex and the total solar EUV flux with λ < 1050 Å; and (iii) a combined analysis of the ionospheric and thermospheric parameter long-term variations using the theory of ionospheric F-layer formation. Atomic oxygen, [O] and [O]/[N2] ratio control foF1 and foF2 while neutral temperature, Tex controls hmF2 long-term variations. Noontime foF2 and foF1 long-term variations demonstrate a negative linear trend estimated over the (1962-2010) period which is mainly due to atomic oxygen decrease after ˜1990. A linear trend in (δhmF2)11y estimated over the (1962-2010) period is very small and insignificant reflecting the absence of any significant trend in neutral temperature. The retrieved neutral gas density, ρ atomic oxygen, [O] and exospheric temperature, Tex long-term variations are controlled by solar and geomagnetic activity, i.e. they have a natural origin. The residual trends estimated over the period of ˜5 solar cycles (1957-2015) are very small (<0.5% per decade) and statistically insignificant.

Direct estimation of tidally induced Earth rotation variations observed by VLBI

NASA Astrophysics Data System (ADS)

Englich, S.; Heinkelmann, R.; BOHM, J.; Schuh, H.

2009-09-01

The subject of our study is the investigation of periodical variations induced by solid Earth tides and ocean tides in Earth rotation parameters (ERP: polar motion, UT1)observed by VLBI. There are two strategies to determine the amplitudes and phases of Earth rotation variations from observations of space geodetic techniques. The common way is to derive time series of Earth rotation parameters first and to estimate amplitudes and phases in a second step. Results obtained by this means were shown in previous studies for zonal tidal variations (Englich et al.; 2008a) and variations caused by ocean tides (Englich et al.; 2008b). The alternative method is to estimate the tidal parameters directly within the VLBI data analysis procedure together with other parameters such as station coordinates, tropospheric delays, clocks etc. The purpose of this work was the application of this direct method to a combined VLBI data analysis using the software packages OCCAM (Version 6.1, Gauss-Markov-Model) and DOGSCS (Gerstl et al.; 2001). The theoretical basis and the preparatory steps for the implementation of this approach are presented here.

Adjusting for geographic variation in observational comparative effectiveness studies: a case study of antipsychotics using state Medicaid data.

PubMed

Root, Elisabeth Dowling; Thomas, Deborah S K; Campagna, Elizabeth J; Morrato, Elaine H

2014-08-27

Area-level variation in treatment and outcomes may be a potential source of confounding bias in observational comparative effectiveness studies. This paper demonstrates how to use exploratory spatial data analysis (ESDA) and spatial statistical methods to investigate and control for these potential biases. The case presented compares the effectiveness of two antipsychotic treatment strategies: oral second-generation antipsychotics (SGAs) vs. long-acting paliperiodone palmitate (PP). A new-start cohort study was conducted analyzing patient-level administrative claims data (8/1/2008-4/30/2011) from Missouri Medicaid. ESDA techniques were used to examine spatial patterns of antipsychotic prescriptions and outcomes (hospitalization and emergency department (ED) visits). Likelihood of mental health-related outcomes were compared between patients starting PP (N = 295) and oral SGAs (N = 8,626) using multilevel logistic regression models adjusting for patient composition (demographic and clinical factors) and geographic region. ESDA indicated significant spatial variation in antipsychotic prescription patterns and moderate variation in hospitalization and ED visits thereby indicating possible confounding by geography. In the multilevel models for this antipsychotic case example, patient composition represented a stronger source of confounding than geographic context. Because geographic variation in health care delivery is ubiquitous, it could be a comparative effectiveness research (CER) best practice to test for possible geographic confounding in observational data. Though the magnitude of the area-level geography effects were small in this case, they were still statistically significant and should therefore be examined as part of this observational CER study. More research is needed to better estimate the range of confounding due to geography across different types of observational comparative effectiveness studies and healthcare utilization outcomes.

Observations of hysteresis in solar cycle variations among seven solar activity indicators

NASA Technical Reports Server (NTRS)

Bachmann, Kurt T.; White, Oran R.

1994-01-01

We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study, we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar emission at various wavelengths.

Spatio-temporal Variations of Nitrogen Dioxide over Western China from Satellite Observations during 2005-2013

NASA Astrophysics Data System (ADS)

Cui, Y.; Lin, J.; Huang, B.; Song, C.

2015-12-01

Western China has experienced rapid urbanization and industrialization since the implementation of National Western Development Strategy by Chinese Government. Most resource-intensive industries and high-pollution factories had been moved from the east coast to Western China after 2000. In this research, the spatial and temporal variations of tropospheric NO2 concentration in 2005 - 2013 is analyzed based on the satellite observations by Ozone Measurement Instrument (OMI). The annual trends and seasonality of tropospheric NO2 over Western China are calculated. The results show that large increases are observed in urban areas and the polluted regions are expanding. Additionally, the seasonal patterns of some regions over Western China are changing significantly and more clean areas tend to changing from the characteristics of natural emissions to those of anthropogenic emissions. The spatial and temporal variations of NO2 concentrations are well responded to the rapid urbanization and industrialization over Western China.

Latitudinal variations in Titan's methane and haze from Cassini VIMS observations

USGS Publications Warehouse

Penteado, P.F.; Griffith, C.A.; Tomasko, M.G.; Engel, S.; See, C.; Doose, L.; Baines, K.H.; Brown, R.H.; Buratti, B.J.; Clark, R.; Nicholson, P.; Sotin, Christophe

2010-01-01

We analyze observations taken with Cassini's Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60??S and 40??N. The methane variation was measured primarily from its absorption band at 0.61 ??m, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan's 0.4-1.6 ??m spectra, which sample Titan's atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20??S and 10??S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60??S and 40??N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27??S and 19??N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan's visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane

Clonal Expansion of the Pseudogymnoascus destructans Genotype in North America Is Accompanied by Significant Variation in Phenotypic Expression

PubMed Central

Khankhet, Jordan; Vanderwolf, Karen J.; McAlpine, Donald F.; McBurney, Scott; Overy, David P.; Slavic, Durda; Xu, Jianping

2014-01-01

Pseudogymnoascus destructans is the causative agent of an emerging infectious disease that threatens populations of several North American bat species. The fungal disease was first observed in 2006 and has since caused the death of nearly six million bats. The disease, commonly known as white-nose syndrome, is characterized by a cutaneous infection with P. destructans causing erosions and ulcers in the skin of nose, ears and/or wings of bats. Previous studies based on sequences from eight loci have found that isolates of P. destructans from bats in the US all belong to one multilocus genotype. Using the same multilocus sequence typing method, we found that isolates from eastern and central Canada also had the same genotype as those from the US, consistent with the clonal expansion of P. destructans into Canada. However, our PCR fingerprinting revealed that among the 112 North American isolates we analyzed, three, all from Canada, showed minor genetic variation. Furthermore, we found significant variations among isolates in mycelial growth rate; the production of mycelial exudates; and pigment production and diffusion into agar media. These phenotypic differences were influenced by culture medium and incubation temperature, indicating significant variation in environmental condition - dependent phenotypic expression among isolates of the clonal P. destructans genotype in North America. PMID:25122221

Clonal expansion of the Pseudogymnoascus destructans genotype in North America is accompanied by significant variation in phenotypic expression.

PubMed

Khankhet, Jordan; Vanderwolf, Karen J; McAlpine, Donald F; McBurney, Scott; Overy, David P; Slavic, Durda; Xu, Jianping

2014-01-01

Pseudogymnoascus destructans is the causative agent of an emerging infectious disease that threatens populations of several North American bat species. The fungal disease was first observed in 2006 and has since caused the death of nearly six million bats. The disease, commonly known as white-nose syndrome, is characterized by a cutaneous infection with P. destructans causing erosions and ulcers in the skin of nose, ears and/or wings of bats. Previous studies based on sequences from eight loci have found that isolates of P. destructans from bats in the US all belong to one multilocus genotype. Using the same multilocus sequence typing method, we found that isolates from eastern and central Canada also had the same genotype as those from the US, consistent with the clonal expansion of P. destructans into Canada. However, our PCR fingerprinting revealed that among the 112 North American isolates we analyzed, three, all from Canada, showed minor genetic variation. Furthermore, we found significant variations among isolates in mycelial growth rate; the production of mycelial exudates; and pigment production and diffusion into agar media. These phenotypic differences were influenced by culture medium and incubation temperature, indicating significant variation in environmental condition--dependent phenotypic expression among isolates of the clonal P. destructans genotype in North America.

Spectral variations of LMC X-3 observed with Ginga

NASA Technical Reports Server (NTRS)

Ebisawa, Ken; Makino, Fumiyoshi; Mitsuda, Kazuhisa; Belloni, Tomaso; Cowley, Anne P.; Schmidtke, Paul C.; Treves, Aldo

1993-01-01

The prime black hole candidate LMC X-3 was observed over three years with the Ginga satellite, and a characteristic spectral variation was found accompanying the periodic intensity variation of about 198 (or possibly about 99) days (Cowley et al., 1991). The energy spectrum of LMC X-3 consists of the soft, thermal component and the hard, power-law component, which are respectively dominant below and above about 9 keV. The soft component, which carries most of the X-ray intensity, shows a clear correlation between the intensity and the hardness, while the hard component varies independently of the soft component. It was found that the spectral variation of the soft component is well described by an optically thick accretion disk model with a remarkably constant innermost radius and variable mass accretion rate. The constancy of the innermost radius suggests it is related to the mass of the central object.

Reduction of observer variation using matched CT-PET for lung cancer delineation: A three-dimensional analysis

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

Steenbakkers, Roel; Duppen, Joop C.; Fitton, Isabelle

2006-02-01

common and encompassing volume was 0.17 and 0.29 for the first and second phases, respectively. For the first phase, the common volume was 0 in 4 patients (i.e., no common point for all GTVs). In the second phase, the common volume was always >0. For all anatomic regions, the interpretation differences among the radiation oncologists were reduced. The amount of disagreement was 45% and 18% for the first and second phase, respectively. Furthermore, the mean delineation time (12 vs. 16 min, p < 0.001) and mean number of corrections (25 vs. 39, p < 0.001) were reduced in the second phase compared with the first phase. Conclusion: For high-precision radiotherapy, the delineation of lung target volumes using only CT introduces too great a variability among radiation oncologists. Implementing matched CT-FDG-PET and adapted delineation protocol and software reduced observer variation in lung cancer delineation significantly with respect to CT only. However, the remaining observer variation was still large compared with other geometric uncertainties (setup variation and organ motion)« less

Variations of Solar Radius Observed with RHESSI

NASA Astrophysics Data System (ADS)

Fivian, M. D.; Hudson, H. S.; Lin, R. P.

2003-12-01

The Solar Aspect System (SAS) of the rotating (at 15 rpm) RHESSI spacecraft has three subsystems. Each of these measures the position of the limb by sampling the full solar chord profile with a linear CCD using a narrow bandwidth filter at 670 nm. With a resolution of each CCD of 1.7 arcsec/pixel, the accuracy of each of the 6 limb positions is theoretically better than 50 mas using 4 pixels at each limb. Since the launch of RHESSI early 2002, solar limbs are sampled with at least 100 Hz. That provides a database of currently 4 x 109 single radius measurements. The main function of SAS is to determine the RHESSI pointing relative to Sun center. The observed precision of this determination has a typical instantaneous (16 Hz) value of about 200 mas (rms). We show and discuss first results of variations of solar radius observed with RHESSI.

Possible causes of variation in acrylamide concentration in French fries prepared in food service establishments: an observational study.

PubMed

Sanny, M; Jinap, S; Bakker, E J; van Boekel, M A J S; Luning, P A

2012-05-01

Acrylamide is a probable human carcinogen, and its presence in a range of fried and oven-cooked foods has raised considerable health concern world-wide. Dietary intake studies observed significant variations in acrylamide concentrations, which complicate risk assessment and the establishment of effective control measures. The objective of this study was to obtain an insight into the actual variation in acrylamide concentrations in French fries prepared under typical conditions in a food service establishment (FSE). Besides acrylamide, frying time, frying temperature, and reducing sugars were measured and the actual practices at receiving, thawing and frying during French fries preparation were observed and recorded. The variation in the actual frying temperature contributed most to the variation in acrylamide concentrations, followed by the variation in actual frying time; no obvious effect of reducing sugars was found. The lack of standardised control of frying temperature and frying time (due to inadequate frying equipment) and the variable practices of food handlers seem to contribute most to the large variation and high acrylamide concentrations in French fries prepared in a restaurant type of FSE as compared to chain fast-food services, and institutional caterers. The obtained insights in this study can be used to develop dedicated control measures in FSE, which may contribute to a sustainable reduction in the acrylamide intake. Copyright © 2011 Elsevier Ltd. All rights reserved.

The time variation of atomic oxygen emission around Io during a volcanic event observed with Hisaki/EXCEED

NASA Astrophysics Data System (ADS)

Koga, Ryoichi; Tsuchiya, Fuminori; Kagitani, Masato; Sakanoi, Takeshi; Yoneda, Mizuki; Yoshioka, Kazuo; Kimura, Tomoki; Murakami, Go; Yamazaki, Atsushi; Yoshikawa, Ichiro; Smith, H. Todd

2018-01-01

Io has an atmosphere produced by volcanism and sublimation of frosts deposited around active volcanoes. However, the time variation of atomic oxygen escaping Io's atmosphere is not well known. In this paper, we show a significant increase in atomic oxygen around Io during a volcanic event. Brightening of Io's extended sodium nebula was observed in the spring of 2015. We used the Hisaki satellite to investigate the time variation of atomic oxygen emission around Io during the same period. This investigation reveals that the duration of atomic oxygen brightness increases from a volcanically quiet level to a maximum level during the same approximate time period of 30 days as the observed sodium brightness. On the other hand, the recovery of the atomic oxygen brightness from the maximum to the quiet level (60 days) was longer than that of the sodium nebula decreasing (40 days). Additionally, a dawn-dusk asymmetry of the atomic oxygen emission is observed.

Atmospheric diurnal and semi-diurnal variations observed with GPS radio occultation soundings

NASA Astrophysics Data System (ADS)

Xie, F.; Wu, D. L.; Ao, C. O.; Mannucci, A. J.

2009-11-01

Diurnal and semi-diurnal variations, driven by solar forcing, are two fundamental modes in the Earth's weather and climate system. Radio occultation (RO) measurements from the six COSMIC satellites (Constellation Observing System for Meteorology Ionosphere and Climate) provide rather uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal and semi-diurnal variations of both temperature and refractivity from two-year (2007-2008) COSMIC RO measurements in the troposphere and stratosphere. The RO observations reveal both propagating and trapped vertical structures of diurnal and semi-diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity decreases with altitude from a local maximum in the planetary boundary layer and reaches the minimum around 14 km and then further increase amplitude in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from upper troposphere to the stratopause with a vertical wavelength of about 25 km. Below 500 hPa (~5.5 km), seasonal variations of the peak diurnal amplitude in the tropics follow the solor forcing change in latitude, while at 30 km the seasonal pattern reverses with the diurnal amplitude peaking at the opposite side of the equator relative to the solar forcing. Polar regions shows large diurnal variations in the stratosphere with strong seasonal variations and the cause(s) of these variations require further investigations.

Chemical variations observed on Aeolis Mons in Gale Crater, Mars

NASA Astrophysics Data System (ADS)

Frydenvang, Jens; Gasda, Patrick J.; Thompson, Lucy; Hurowitz, Joel; Grotzinger, John P.; Blaney, Diana L.; Gellert, Ralf; Wiens, Roger; Vasavada, Ashwin R.; MSL Science Team

2016-10-01

The extraordinarily extensive exposure of hematite-, clay-, sulfate-bearing stratigraphic layers in the lower part of Aeolis Mons was the primary reason Gale Crater was selected as the landing site for the Mars Science Laboratory rover, Curiosity. 753 martian solar days (sols) after the Curiosity rover landed in Gale Crater in August 2012, and after driving more than 9 km, the Curiosity rover arrived at the first exposure of the Murray formation, the basal layer of Aeolis Mons. The Murray formation is a thinly laminated lacustrine mudstone showing stratification down to the millimeter scale. This supports the idea that the stratigraphic layers of Aeolis Mons are sedimentary, and likely deposited in a series of long-lived lakes extending into the early Hesperian time, as recently described by Grotzinger et al. (Science, vol. 350, 2015). The chemical variations observed throughout the Murray formation by the ChemCam and APXS instruments in the 600+ sols since first arriving at Aeolis Mons will be presented. While Murray remains thinly laminated throughout the 30+ vertical meters of stratigraphy explored, large chemical variations are observed. The most extreme variations arise from likely co-located detrital and diagenetic silica enrichments in Murray. Remarkably, an associated diagenetic silica enrichment is also observed in the unconformably overlying eolian sandstone of the Stimson formation in that location. The detrital enrichment provides evidence of how the source region chemistry varied as the sedimentary layers of Aeolis Mons were deposited. Conversely, the diagenetic enrichment observed across both the Murray and Stimson formations provides compelling evidence for the presence of subsurface fluids in Gale Crater, thousands to millions of years after the crater lakes disappeared. This evidence of liquid water greatly extends the timescale in which Gale Crater might have been habitable.

SSI Variations in the visible as observed with SOLAR/SOLSPEC during cycle 24 - Comparison with SORCE/SIM.

NASA Astrophysics Data System (ADS)

Irbah, A.; Damé, L.; Meftah, M.; Bekki, S.; Bolsée, D.

2017-12-01

The solar spectral irradiance (SSI) and its temporal variations are of prime importance to apprehend the physics of the Sun and to understand its effects on Earth climate through changes of atmospheric properties. Ground based measurements of SSI are indeed affected by the Earth atmosphere and space observations are therefore required to perform adequate observations. Only a few long series of SSI space measurements were obtained these last decades. The SOLSPEC instrument of the SOLAR payload on the International Space Station (ISS) has recorded one of them from April 2008 to February 2017 covering almost the whole solar cycle 24. The instrument is a spectro-radiometer recording data of the Sun from 166 to 3088 nm. Operated from the ISS in a harsh environment it needed appropriate processing methods to extract significant scientific results from noise and instrumental effects. We present the methods used to process the data to evidence visible SSI variations during cycle 24. We discuss the results obtained showing SSI variations in phase with solar activity. We compare them with SORCE/SIM measurements.

Long-term tropospheric and lower stratospheric ozone variations from ozonesonde observations

NASA Technical Reports Server (NTRS)

London, J.; Liu, S. C.

1992-01-01

An analysis is presented of the long-term mean pressure-latitude seasonal distribution of tropospheric and lower stratospheric ozone for the four seasons covering, in part, over 20 years of ozonesonde data. The observed patterns show minimum ozone mixing ratios in the equatorial and tropical troposphere except in regions where net photochemical production is dominant. In the middle and upper troposphere, and low stratosphere to 50 mb, ozone increases from the tropics to subpolar latitudes of both hemispheres. In mid stratosphere, the ozone mixing ratio is a maximum over the tropics. The observed vertical ozone gradient is small in the troposphere but increases rapidly above the tropopause. The amplitude of the annual variation increases from a minimum in the tropics to a maximum in polar regions. Also, the amplitude increases with height at all latitudes up to about 30 mb where the phase of the annual variation changes abruptly. The phase of the annual variation is during spring in the boundary layer, summer in mid troposphere, and spring in the upper troposhere and lower stratosphere.

High Frequency Variations in Earth Orientation Derived From GNSS Observations

NASA Astrophysics Data System (ADS)

Weber, R.; Englich, S.; Snajdrova, K.; Boehm, J.

2006-12-01

Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Orientation Parameters (EOPs - polar motion, UT1/LOD, nutation offsets) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the EOP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the period from begin of 2005 till March 2006. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 79 fairly stable stations out of the IGb00 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed. Finally, satellite techniques are also able to provide nutation offset rates with respect to the most recent nutation model. Based on GPS observations from 2005 we established nutation rate time series and subsequently derived the amplitudes of several nutation waves with periods less than 30 days. The results are compared to VLBI estimates processed by means of the OCCAM 6.1 software.

Ionospheric variation observed in Oregon Real-time GNSS network during the total eclipse of 21 August 2017

NASA Astrophysics Data System (ADS)

Shahbazi, A.; Park, J.; Kim, S.; Oberg, R.

2017-12-01

As the ionospheric behavior is highly related to the solar activity, the total eclipse passing across the North America on 21 August 2017 is expected to significantly affect the electron density in the ionosphere along the path. Taking advantage of GNSS capability for observing total electron content (TEC), this study demonstrates the impact of the total eclipse not only on the TEC variation during the period of the event but also on GNSS positioning. Oregon Department of Transportation (ODOT) runs a dense real time GNSS network, referred to as Oregon Real-time GNSS network (ORGN). From the dual frequency GPS and GLONASS observations in ORGN, the TEC over the network area can be extracted. We observe the vertical TEC (VTEC) from the ORGN for analyzing the ionospheric condition in the local area affected by the eclipse. To observe the temporal variation, we also observe the slant TEC (STEC) in each ray path and analyze the short term variation in different geometry of each ray path. Although the STEC is dependent quantity upon the changing geometry of a satellite, this approach provides insight to the ionospheric behavior of the total eclipse because the STEC does not involve the projection error, which is generated by VTEC computation. During the period of eclipse, the abnormal variations on VTEC and STEC are expected. The experimental results will be presented in time series plots for selected stations as well as the regional TEC map in Oregon. In addition to the TEC monitoring, we also test the positioning result of ORGN stations through Precise Point Positioning (PPP) and relative positioning. The expected result is that the both positioning results are degraded during the solar eclipse due to the instable ionospheric condition over short time.

Vascular Variations Associated with Intracranial Aneurysms.

PubMed

Orakdogen, Metin; Emon, Selin Tural; Somay, Hakan; Engin, Taner; Is, Merih; Hakan, Tayfun

2017-01-01

To investigate the vascular variations in patients with intracranial aneurysm in circle of Willis. We used the data on 128 consecutive intracranial aneurysm cases. Cerebral angiography images were analyzed retrospectively. Arteries were grouped as anterior cerebral arterial system (ACS), posterior cerebral arterial system (PCS) and middle cerebral arterial system (MCS) for grouping vascular variations. Lateralization, being single/multiple, gender; and also any connection with accompanying aneurysms" number, localization, dimension, whether bleeding/incidental aneurysm has been inspected. Variations were demonstrated in 57.8% of the cases. The most common variation was A1 variation (34.4%). The rate of variations was 36.7%, 24.2% and 10.2% respectively in ACS, PCS and MCS. MCS variations were significantly higher in males. Anterior communicating artery (ACoA) aneurysm observance rates were significantly higher and posterior communicating artery (PCoA) aneurysm and middle cerebral artery (MCA) aneurysm observance rates were significantly lower when compared to "no ACS variation detected" cases. In "PCS variation detected" cases, PCoA aneurysm observance rates and coexistence of multiple variations were significantly higher. The rate of vascular variations in patients with aneurysms was 57.8%. Arterial hypoplasia and aplasia were the most common variations. ACS was the most common region that variations were located in; they were mostly detected on the right side. Coexistence of ACoA aneurysm was higher than PCoA and MCA aneurysms. In the PCS variations group, PCoA aneurysms were the most common aneurysms that accompanying the variation and multiple variations were more common than in the other two groups. The variations in MCS were most common in males.

Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

NASA Technical Reports Server (NTRS)

Kuang, Weijia; Tangborn, Andrew

2014-01-01

Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

NASA Technical Reports Server (NTRS)

Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.;

Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

PubMed

Lefèvre, Franck; Forget, François

2009-08-06

The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

Variations of GHGs from the lower-troposphere to the UT/LS revealed by two Japanese regular aircraft observation programs

NASA Astrophysics Data System (ADS)

Niwa, Yosuke; Machida, Toshinobu; Sawa, Yousuke; Tsuboi, Kazuhiro; Matsueda, Hidekazu; Imasu, Ryoichi

2014-05-01

A Japan-centered observation network consisting of two regular aircraft programs have revealed the greenhouse gases variations from the lower-troposphere to the upper-troposphere/lower-stratosphere (UT/LS) regions. In the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project, in-situ continuous measurement equipment (CME) onboard commercial passenger aircraft world-widely observes CO2 profiles in vertical over tens of airports and in horizontal in the UT/LS regions. The CONTRAIL-CME has revealed three-dimensional structure of the global CO2 distribution and has exposed significant inter-hemispheric transport of CO2 through the upper-troposphere. In inverse modeling, the CME data have provided strong constraints on CO2 flux estimation especially for the Asian tropics. Automatic flask air sampling equipment (ASE) is also onboard the CONTRAIL aircraft and has been observing CO2 mixing ratios as well as those of methane, carbon monoxide, nitrous oxide and other trace species in the upper-troposphere between Japan and Australia. The observation period of the ASE has reached 20 years. In recent years, the ASE program has extended to the northern subarctic UT/LS region and has given an insight of transport mechanisms in the UT/LS by observing seasonal GHGs variations. In the other aircraft observation program by Japan Meteorological Agency, variations of GHGs have been observed by flask-sampling onboard a C-130H aircraft horizontally in the mid-troposphere over the western North Pacific as well as vertically over Minamitorishima-Island. The C-130H aircraft has persistently observed high mixing ratios of CH4 in the mid-troposphere, which seems to be originated from fossil fuel combustion throughout the year as well as from biogenic sources during summer in the Asian regions. Those above aircraft observation programs have a significant role for constraining GHGs flux estimates by filling the data gap of the existing surface measurement network

Effects of the observed J2 variations on the Earth's precession and nutation

NASA Astrophysics Data System (ADS)

Ferrándiz, José M.; Baenas, Tomás; Belda, Santiago

2016-04-01

The Earth's oblateness parameter J2 is closely related to the dynamical ellipticity H, which factorizes the main components of the precession and the different nutation terms. In most theoretical approaches to the Earth's rotation, with IAU2000 nutation theory among them, H is assumed to be constant. The precession model IAU2006 supposes H to have a conventional linear variation, based on the J2 time series derived mainly from satellite laser ranging (SLR) data for decades, which gives rise to an additional quadratic term of the precession in longitude and some corrections of the nutation terms. The time evolution of J2 is, however, too complex to be well approximated by a simple linear model. The effect of more general models including periodic terms and closer to the observed time series, although still unable to reproduce a significant part of the signal, has been seldom investigated. In this work we address the problem of deriving the effect of the observed J2 variations without resorting to such simplified models. The Hamiltonian approach to the Earth rotation is extended to allow the McCullagh's term of the potential to depend on a time-varying oblateness. An analytical solution is derived by means of a suitable perturbation method in the case of the time series provided by the Center for Space Research (CSR) of the University of Texas, which results in non-negligible contributions to the precession-nutation angles. The presentation focuses on the main effects on the longitude of the equator; a noticeable non-linear trend is superimposed to the linear main precession term, along with some periodic and decadal variations.

Dust variations in the diffuse interstellar medium: constraints on Milky Way dust from Planck-HFI observations

NASA Astrophysics Data System (ADS)

Ysard, N.; Köhler, M.; Jones, A.; Miville-Deschênes, M.-A.; Abergel, A.; Fanciullo, L.

2015-05-01

Context. The Planck-HFI all-sky survey from 353 to 857 GHz combined with the IRAS data at 100 μm (3000 GHz, IRIS version of the data) show that the dust properties vary from line of sight to line of sight in the diffuse interstellar medium (ISM) at high Galactic latitude (1019 ≤ NH ≤ 2.5 × 1020 H/cm2, for a sky coverage of ~12%). Aims: These observations contradict the usual thinking of uniform dust properties, even in the most diffuse areas of the sky. Thus, our aim is to explain these variations with changes in the ISM properties and with evolution of the grain properties. Methods: Our starting point is the latest core-mantle dust model. This model consists of small aromatic-rich carbon grains, larger amorphous carbonaceous grains with an aliphatic-rich core and an aromatic-rich mantle, and amorphous silicates (mixture of olivine and pyroxene types) with Fe/FeS nano-inclusions covered by aromatic-rich carbon mantles. We explore whether variations in the radiation field or in the gas density distribution in the diffuse ISM could explain the observed variations. The dust properties are also varied in terms of their mantle thickness, metallic nano-inclusions, carbon abundance locked in the grains, and size distributions. Results: We show that variations in the radiation field intensity and gas density distribution cannot explain variations observed with Planck-HFI but that radiation fields harder than the standard ISRF may participate in creating part of the observed variations. We further show that variations in the mantle thickness on the grains coupled with changes in their size distributions can reproduce most of the observations. We concurrently put a limit on the mantle thickness of the silicates, which should not exceed ~ 10 to 15 nm, and find that aromatic-rich mantles are definitely needed for the carbonaceous grain population with a thickness of at least 5 to 7.5 nm. We also find that changes in the carbon cosmic abundance included in the grains

Interstellar extinction curve variations towards the inner Milky Way: a challenge to observational cosmology

NASA Astrophysics Data System (ADS)

Nataf, David M.; Gonzalez, Oscar A.; Casagrande, Luca; Zasowski, Gail; Wegg, Christopher; Wolf, Christian; Kunder, Andrea; Alonso-Garcia, Javier; Minniti, Dante; Rejkuba, Marina; Saito, Roberto K.; Valenti, Elena; Zoccali, Manuela; Poleski, Radosław; Pietrzyński, Grzegorz; Skowron, Jan; Soszyński, Igor; Szymański, Michał K.; Udalski, Andrzej; Ulaczyk, Krzysztof; Wyrzykowski, Łukasz

2016-03-01

We investigate interstellar extinction curve variations towards ˜4 deg2 of the inner Milky Way in VIJKs photometry from the OGLE-III (third phase of the Optical Gravitational Lensing Experiment) and VVV (VISTA Variables in the Via Lactea) surveys, with supporting evidence from diffuse interstellar bands and F435W, F625W photometry. We obtain independent measurements towards ˜2000 sightlines of AI, E(V - I), E(I - J) and E(J - Ks), with median precision and accuracy of 2 per cent. We find that the variations in the extinction ratios AI/E(V - I), E(I - J)/E(V - I) and E(J - Ks)/E(V - I) are large (exceeding 20 per cent), significant and positively correlated, as expected. However, both the mean values and the trends in these extinction ratios are drastically shifted from the predictions of Cardelli and Fitzpatrick, regardless of how RV is varied. Furthermore, we demonstrate that variations in the shape of the extinction curve have at least two degrees of freedom, and not one (e.g. RV), which we confirm with a principal component analysis. We derive a median value of = 13.44, which is ˜60 per cent higher than the `standard' value. We show that the Wesenheit magnitude WI = I - 1.61(I - J) is relatively impervious to extinction curve variations. Given that these extinction curves are linchpins of observational cosmology, and that it is generally assumed that RV variations correctly capture variations in the extinction curve, we argue that systematic errors in the distance ladder from studies of Type Ia supernovae and Cepheids may have been underestimated. Moreover, the reddening maps from the Planck experiment are shown to systematically overestimate dust extinction by ˜100 per cent and lack sensitivity to extinction curve variations.

Pressure Variations in Metamorphic Rocks: Implications for the Interpretation of Petrographic Observations

NASA Astrophysics Data System (ADS)

Tajčmanová, Lucie

2014-05-01

Metamorphic petrologists and structural geologists, using direct measurements, bring the only direct observational constrains for validating geodynamic models. Therefore, petrological and structural geological observations are essential for the quality and reproducibility of geodynamic reconstructions and models. One of the important assumptions for geodynamic reconstructions arises from the pressure and temperature estimates in the petrology analysis. Pressure is commonly converted to depth through the equation for lithostatic pressure and so the original position of the rock sample within the Earth's interior can be constrained. The current assumption that the studied sample corresponds to uniform pressure may not be correct, and if so, it has serious implications. Increasing evidence from analytical data shows that pressure is not constant even on a grain scale, posing new challenges because, if ignored, it leads to an incorrect use of petrology data in constraining geodynamic models. Well known examples of the preservation of coesite and diamond in a host mineral like garnet show that high pressure inclusions are preserved during decompression. Tajčmanová et al. (2014) has shown that grain-scale pressure variations can develop and that these pressure variations allow compositional zoning in minerals preserved over geological time scales. A new unconventional barometric method based on equilibrium under pressure variations has been developed . Such pressure variations are also connected with differences in fluid pressure in open systems and can be thus observed at all scales. Tajčmanová L., Podladchikov Y., Powell R., Moulas E., Vrijmoed J. and Connolly J. (2014). Grain scale pressure variations and chemical equilibrium in high-grade metamorphic rocks.Journal of Metamorphic Geology, doi:10.1111/jmg.12066 This work was supported by ERC starting grant 335577 to Lucie Tajcmanova

Are Observed Variations of Topography of The '660' Influenced By Lateral Variations of An Underlying Interface ?

NASA Astrophysics Data System (ADS)

Castillo, J.; Mocquet, A.; Vacher, P.; Sotin, C.

Most global studies of lateral variations of topography of the '660' have been per- formed so far with long-period data. This presentation assess the seismic signature of this region when studied with broadband data in the frequency range 0.1-1 Hz. When sampled with P-to-s converted phases, this region shows a complex pattern, associat- ing 3 interfaces at the average depths of 600, 650 and 715 km. First results indicate that lateral topography variations of the '650' fit previous observations by long-period data (Gu et al., 1998), except in some subduction zones, especially in East Asia, where vari- ation trends appear to behave in an opposite way. In such regions, better correlations are found with the behaviour of the '715'. We propose that the seismic signature of long-period waves generated at the bottom of the transition zone may be influenced by both interfaces. Because of the lateral variations of their thickness and velocity jump as a function of thermal context, the signature of one interface could prevail against the other. The transformation of garnet into perovskite, and dissociation of ringwood- ite are tested as possible candidates for the '715' and '650', respectively (Vacher et al., 1998), using available thermoelastic data. Synthetic modelling of converted phases on the velocity profiles computed in different thermal contexts can explain our broadband observations. References : Gu et al., EPSL, 157, 57-67, 1998 ; Vacher et al., PEPI, 106, 275-298, 1998.

Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.

PubMed

Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B

2016-08-24

Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.

Modeling the Observed QBO and Inter-Annual Variations of the Diurnal Tide in the Mesosphere

NASA Technical Reports Server (NTRS)

Mayr, Hans G.; Mengel, John G.; Huang, F. T.

2006-01-01

In the current version of the Numerical Spectral Model (NSM), the Quasi-biennial Oscillation (QBO) is generated primarily by small-scale gravity waves (GW) from Hines' Doppler Spread Parameterization (DSP). The model does not have topography, and the planetary waves are solely generated by instabilities. We discuss a 3D modeling study that describes the QBO extending from the stratosphere into the upper mesosphere, where the oscillation produces significant inter-annual variations in the diurnal tide. The numerical results are compared with temperature measurements from the SABER (TIMED) and MLS (UARS) instruments obtained by Huang et al. (2006). With a GW source that peaks at the Equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 26 months and zonal wind amplitudes of almost 25 m/s at 30 km. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. The modeled QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. To shed light on the underlying mechanisms, the relative importance of the advection terms are discussed, and they are shown to be important in the stratosphere. At altitudes above 80 km, however, the QBO-related inter-annual variations of the tide are generated primarily by GW momentum deposition. In qualitative agreement with the SABER measurements, the model generates distinct zonal-mean QBO temperature variations in the stratosphere and mesosphere. In the stratosphere, the computed amplitudes are not much smaller than those observed, and the rate of downward propagation at the Equator is reproduced. The modeled temperature amplitudes in the mesosphere, however, are much smaller than those observed. The observed and computed temperature variations of the QBO peak at the Equator but extend with phase reversals to high latitudes, in contrast to the zonal winds that are

Observation of pressure variation in the cavitation region of submerged journal bearings

NASA Technical Reports Server (NTRS)

Etsion, I.; Ludwig, L. P.

1981-01-01

Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests are run at speeds of 1840 and 3000 rpm, and at each speed, four different levels of the ambient supply pressure are applied, ranging from 13.6 KPa to 54.4 KPa. A strong reverse flow is detected inside the cavitation area adjacent to its downstream end, and significant pressure variations on the order of 50 KPa are found inside the cavitation region at the downstream portion of its circumferential extent. Results indicate that the assumption of a constant cavitation pressure is incorrect in the case of enclosed cavitations, and it is postulated that oil which is saturated with air under atmospheric pressure becomes oversaturated in the subcavity pressure loop.

Diurnal variations of BrONO2 observed by MIPAS-B at midlatitudes and in the Arctic

NASA Astrophysics Data System (ADS)

Wetzel, Gerald; Oelhaf, Hermann; Höpfner, Michael; Friedl-Vallon, Felix; Ebersoldt, Andreas; Gulde, Thomas; Kazarski, Sebastian; Kirner, Oliver; Kleinert, Anne; Maucher, Guido; Nordmeyer, Hans; Orphal, Johannes; Ruhnke, Roland; Sinnhuber, Björn-Martin

2017-12-01

The first stratospheric measurements of the diurnal variation in the inorganic bromine (Bry) reservoir species BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68° N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 21 pptv (parts per trillion by volume) were detected in late winter 2011 in the absence of polar stratospheric clouds (PSCs). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 due to low available NO2 amounts (for the build-up of BrONO2), the heterogeneous destruction of BrONO2 on PSC particles, and the gas-phase interaction of BrO (the source to form BrONO2) with ClO. A further balloon flight took place at midlatitudes from Timmins (49° N, Canada) in September 2014. Mean BrONO2 mixing ratios of 22 pptv were observed after sunset in the altitude region between 21 and 29 km. Measurements are compared and discussed with the results of a multi-year simulation performed with the chemistry climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). The calculated temporal variation in BrONO2 largely reproduces the balloon-borne observations. Using the nighttime simulated ratio between BrONO2 and Bry, the amount of Bry observed by MIPAS-B was estimated to be about 21-25 pptv in the lower stratosphere.

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data

NASA Astrophysics Data System (ADS)

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.; Yin, Yunhe; Kumar, Jitendra; Ma, Chun; Xu, Xiaofeng

2017-09-01

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. We compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62). However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S-10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1-0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.

Bayesian Analysis Of HMI Solar Image Observables And Comparison To TSI Variations And MWO Image Observables

NASA Astrophysics Data System (ADS)

Parker, D. G.; Ulrich, R. K.; Beck, J.

2014-12-01

We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from May, 2010 to June, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables. The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment. Ulrich, R.K., Parker, D, Bertello, L. and

Variations in the Geometry of the Sun Observed with HMI/SDO during Cycle 24

NASA Astrophysics Data System (ADS)

Irbah, Abdenour; Damé, Luc

2016-10-01

Geometry of the Sun and its temporal variations observed with ground-based instruments are still subject to questioning. The geometry, which inform us on the interior of the Sun, is achieved by high resolution measurements of the radius, oblateness and gravitational moments c2 and c4. Several space missions were developed these last decades to validate or refute its observed variations with ground experiments and the link with solar activity. High angular resolution of solar radius measurements and its long term trend is however a challenge in Space. The first attempts with MDI (Soho) then SODISM (PICARD) and HMI (SDO) revealed the difficulties of such measures due to hostile environment which introduces thermal variations of the instruments along the satellite orbit. These variations have non negligible impacts on optical properties of onboard telescopes and therefore on images and parameters extracted, such as the solar radius. We need to take into account the thermal behavior (housekeeping data) recorded together with the science data to correct them. Solar oblateness and gravitational moments ask for both special spacecraft operations and appropriate processing methods to obtain the needed accuracy for their measurements. We present here some results on the solar radius and oblateness obtained with HMI data. Images analysed cover six years since May 1, 2010 (beginning of Cycle 24), until now. Results show that the geometry of the Sun presents some temporal variations related to solar activity. In particular we evidence a Quasi-Biennale Oscillation (QBO) correlated with the solar cycle, as was observed with ground observations.

Observations of Transient ISS Floating Potential Variations During High Voltage Solar Array Operations

NASA Technical Reports Server (NTRS)

Willis, Emily M.; Minow, Joseph I.; Parker, Linda N.; Pour, Maria Z. A.; Swenson, Charles; Nishikawa, Ken-ichi; Krause, Linda Habash

2016-01-01

The International Space Station (ISS) continues to be a world-class space research laboratory after over 15 years of operations, and it has proven to be a fantastic resource for observing spacecraft floating potential variations related to high voltage solar array operations in Low Earth Orbit (LEO). Measurements of the ionospheric electron density and temperature along the ISS orbit and variations in the ISS floating potential are obtained from the Floating Potential Measurement Unit (FPMU). In particular, rapid variations in ISS floating potential during solar array operations on time scales of tens of milliseconds can be recorded due to the 128 Hz sample rate of the Floating Potential Probe (FPP) pro- viding interesting insight into high voltage solar array interaction with the space plasma environment. Comparing the FPMU data with the ISS operations timeline and solar array data provides a means for correlating some of the more complex and interesting transient floating potential variations with mission operations. These complex variations are not reproduced by current models and require further study to understand the underlying physical processes. In this paper we present some of the floating potential transients observed over the past few years along with the relevant space environment parameters and solar array operations data.

Observed diurnal variations in Mars Science Laboratory Dynamic Albedo of Neutrons passive mode data

NASA Astrophysics Data System (ADS)

Tate, C. G.; Moersch, J.; Jun, I.; Mitrofanov, I.; Litvak, M.; Boynton, W. V.; Drake, D.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Maclennan, E.; Malakhov, A.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Vostrukhin, A.

2018-06-01

The Mars Science Laboratory Dynamic Albedo of Neutrons (DAN) experiment measures the martian neutron leakage flux in order to estimate the amount of water equivalent hydrogen present in the shallow regolith. When DAN is operating in passive mode, it is sensitive to neutrons produced through the interactions of galactic cosmic rays (GCR) with the regolith and atmosphere and neutrons produced by the rover's Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). During the mission, DAN passive mode data were collected over the full diurnal cycle at the locations known as Rocknest (sols 60-100) and John Klein (sols 166-272). A weak, but unexpected, diurnal variation was observed in the neutron count rates reported at these locations. We investigate different hypotheses that could be causing these observed variations. These hypotheses are variations in subsurface temperature, atmospheric pressure, the exchange of water vapor between the atmosphere and regolith, and instrumental effects on the neutron count rates. Our investigation suggests the most likely factors contributing to the observed diurnal variations in DAN passive data are instrumental effects and time-variable preferential shielding of alpha particles, with other environmental effects only having small contributions.

Ionosphere of Venus - First observations of day-night variations of the ion composition

NASA Technical Reports Server (NTRS)

Taylor, H. A., Jr.; Brinton, H. C.; Bauer, S. J.; Hartle, R. E.; Cloutier, P. A.; Daniell, R. E., Jr.; Donahue, T. M.

1979-01-01

Preliminary observations of day-night variations in the ion composition of the ionosphere of Venus, obtained by the Pioneer Venus Orbiter ion mass spectrometer experiment, are reported. A remarkable abundance and extent of ionization in the deep regions of the nightside ionosphere was observed, in spite of the long Venus night. A comparison of dayside and nightside ion distributions reveals a nightside composition similar in several respects to that of the dayside, with the ions O(+) and O2(+) forming the nightside F 2 and F 1 regions, respectively, as in the dayside. Important differences include a greater abundance of low-latitude ionization in the nightside, a significant increase of H(+) and NO(+) ions with increasing solar zenith angle, and extreme dynamic variability of the nightside region above 160 km. Ion composition data support the view that the nightside ionosphere can be maintained by the transport of ionization from the dayside.

Earth observations and photography experiment: Summary of significant results

NASA Technical Reports Server (NTRS)

El-Baz, F.

1978-01-01

Observation and photographic data from the Apollo Soyuz Test Project are analyzed. The discussion is structured according to the fields of investigation including: geology, desert studies, oceanography, hydrology, and meteorology. The data were obtained by: (1) visual observations of selected Earth features, (2) hand-held camera photography to document observations, and (3) stereo mapping photography of areas of significant scientific interest.

Optimal Observations for Variational Data Assimilation

NASA Technical Reports Server (NTRS)

Koehl, Armin; Stammer, Detlef

2003-01-01

An important aspect of Ocean state estimation is the design of an observing system that allows the efficient study of climate aspects in the ocean. A solution of the design problem is presented here in terms of optimal observations that emerge as nondimensionalized singular vectors of the modified data resolution matrix. The actual computation is feasible only for scalar quantities in the limit of large observational errors. In the framework of a lo resolution North Atlantic primitive equation model it is demonstrated that such optimal observations when applied to determining the strength of the volume and heat transport across the Greenland-Scotland ridge, perform significantly better than traditional section data. On seasonal to inter-annual time-scales optimal observations are located primarily along the continental shelf and information about heat-transport, wind stress and stratification is being communicated via boundary waves and advective processes. On time-scales of about a month, sea surface height observations appear to be more efficient in reconstructing the cross-ridge heat transport than hydrographic observations. Optimal observations also provide a tool for understanding how the ocean state is effected by anomalies of integral quantities such as meridional heat transport.

No Timing Variations Observed in Third Transit of Snow-line Exoplanet Kepler-421b

NASA Astrophysics Data System (ADS)

Dalba, Paul A.; Muirhead, Philip S.

2016-07-01

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

Morphology and time variation of the Jovian Far UV aurora: Hubble Space Telescope observations

NASA Technical Reports Server (NTRS)

Gerard, Jean-Claude; Dols, Vincent; Paresce, Francesco; Prange, Renee

1993-01-01

High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). The first set of two images collected 87 min apart in February 1992 shows a bright (approximately or equal to 180 kR) emission superimposed on the background in rotation with the planet. Both Ly alpha images show common regions of enhanced emission but differences are also observed, possibly due to temporal variations. The second group of images obtained on June 23 and 26, 1992 isolates a spectral region near 153 nm dominated by the H2 Lyman bands and continuum. Both pictures exhibit a narrow arc structure fitting the L = 30 magnetotail field line footprint in the morning sector and a broader diffuse aurora in the afternoon. They show no indication of an evening twilight enhancement. Although the central meridian longitudes were similar, significant differences are seen in the two exposures, especially in the region of diffuse emission, and interpreted as signatures of temporal variations. The total power radiated in the H2 bands is approximately or equal to 2 x 10(exp 12) W, in agreement with previous UV spectrometer observations. The high local H2 emission rates (approximately 450 kR) imply a particle precipitation carrying an energy flux of about 5 x 10(exp -2) W/sq m.

Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

NASA Technical Reports Server (NTRS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-01-01

Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

Correlations between variations in solar EUV and soft X-ray irradiance and photoelectron energy spectra observed on Mars and Earth

NASA Astrophysics Data System (ADS)

Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

2013-11-01

extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.

Temperatures of the martian surface and atmosphere: viking observation of diurnal and geometric variations.

PubMed

Kieffer, H H; Christensen, P R; Martin, T Z; Miner, E D; Palluconi, F D

1976-12-11

Selected observations made with the Viking infrared thermal mapper after the first landing are reported. Atmospheric temperatures measured at the latitude of the Viking 2 landing site (48 degrees N) over most of a martian day reveal a diurnal variation of at least 15 K, with peak temperatures occurring near 2.2 hours after noon, implying significant absorption of sunlight in the lower 30 km of the atmosphere by entrained dust. The summit temperature of Arsia Mons varies by a factor of nearly two each day; large diurnal temperature variation is characteristic of the south Tharsis upland and implies the presence of low thermal inertia material. The thermal inertia of material on the floors of several typical large craters is found to be higher than for the surrounding terrain; this suggests that craters are somehow effective in sorting aeolian material. Brightness temperatures of the Viking 1 landing area decrease at large emission angles; the intensity of reflected sunlight shows a more complex dependence on geometry than expected, implying atmospheric as well as surface scattering.

A study of variation characteristics of Gobi broadband emissivity based on field observational experiments in northwestern China

NASA Astrophysics Data System (ADS)

Zheng, Zhi-yuan; Wei, Zhi-gang; Wen, Zhi-ping; Dong, Wen-jie; Li, Zhen-chao; Wen, Xiao-hang; Zhu, Xian; Chen, Chen; Hu, Shan-shan

2018-02-01

Land surface emissivity is a significant variable in energy budgets, land cover assessments, and environment and climate studies. However, the assumption of an emissivity constant is being used in Gobi broadband emissivity (GbBE) parameterization scheme in numerical models because of limited knowledge surrounding the spatiotemporal variation characteristics of GbBE. To address this issue, we analyzed the variation characteristics of GbBE and possible impact factor-surface soil moisture based on long-term continuous and high temporal resolution field observational experiments over a typical Gobi underlying surface in arid and semiarid areas in northwestern China. The results indicate that GbBE has obvious daily and diurnal variation features, especially diurnal cycle characteristics. The multi-year average of the daily average of GbBE is in the range of 0.932 to 0.970 with an average of 0.951 ± 0.008, and the average diurnal GbBE is in the range of 0.880 to 0.940 with an average of 0.906 ± 0.018. GbBE varies with surface soil moisture content. We observed a slight decrease in GbBE with an increase in soil moisture, although this change was not very obvious because of the low soil moisture in this area. Nevertheless, we think that soil moisture must be one of the most significant impact factors on GbBE in arid and semiarid areas. Soil moisture must be taken into account into the parameterization schemes of bare soil broadband emissivity in land surface models. Additional field experiments and studies should be carried out in order to clarify this issue.

Local Time Variation of Water Ice Clouds on Mars as Observed by TES During Aerobraking.

NASA Astrophysics Data System (ADS)

AlJanaahi, A. A.; AlShamsi, M. R.; Smith, M. D.; Altunaiji, E. S.; Edwards, C. S.

2016-12-01

The large elliptical orbit during Mars Global Surveyor aerobraking enabled sampling the martian atmosphere over many local times. The Thermal Emission Spectrometer (TES) aerobraking spectra were taken between Mars Year 23, Ls=180° and Mars Year 24, Ls=30°. These early data from before the main "mapping" part of the mission have been mostly overlooked, and relatively little analysis has been done with them. These datasets have not been used before to study local time variation. Radiative transfer modeling is used to fit the spectra to retrieve surface and atmospheric temperature, and dust and water ice optical depths. Retrievals show significant and systematic variation in water ice cloud optical depth as a function of local time. Cloud optical depth is higher in the early morning (before 9:00) and in the evening (after 17:00) for all seasons observed (Ls=180°-30°). Clouds form consistently in the Tyrrhena region and in the area around Tharsis.

Meteorological control of lower stratospheric minor species variations - An observational example

NASA Technical Reports Server (NTRS)

Alyea, F. N.; Cunnold, D. M.

1978-01-01

Lower stratospheric air trajectories entering the region over Alaska at the approximately 125 mb level during late May, 1975 indicate a substantial shift in the geographical source regions for the air masses present during that time. This shift coincides with an approximately 25% decrease in the observed halocarbon mixing ratios at the 125 mb level as determined from a daily sequence of halocarbon profiles. Since the halocarbon species measured are essentially chemically inactive at this level, the observed variation is linked to the changing meteorological pattern.

Heat flux variations over sea ice observed at the coastal area of the Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Park, Sang-Jong; Choi, Tae-Jin; Kim, Seong-Joong

2013-08-01

This study presents variations of sensible heat flux and latent heat flux over sea ice observed in 2011 from the 10-m flux tower located at the coast of the Sejong Station on King George Island, Antarctica. A period from July to September was selected as a sea ice period based on daily record of sea state and hourly photos looking at the Marian Cove in front of the Sejong Station. For the sea ice period, mean sensible heat flux is about -11 Wm-2, latent heat flux is about +2 W m-2, net radiation is -12 W m-2, and residual energy is -3 W m-2 with clear diurnal variations. Estimated mean values of surface exchange coefficients for momentum, heat and moisture are 5.15 × 10-3, 1.19 × 10-3, and 1.87 × 10-3, respectively. The observed exchange coefficients of heat shows clear diurnal variations while those of momentum and moisture do not show diurnal variation. The parameterized exchange coefficients of heat and moisture produces heat fluxes which compare well with the observed diurnal variations of heat fluxes.

Influence of ocean tides on the diurnal and semidiurnal earth rotation variations from VLBI observations

NASA Astrophysics Data System (ADS)

Gubanov, V. S.; Kurdubov, S. L.

2015-05-01

The International astrogeodetic standard IERS Conventions (2010) contains a model of the diurnal and semidiurnal variations in Earth rotation parameters (ERPs), the pole coordinates and the Universal Time, arising from lunisolar tides in the world ocean. This model was constructed in the mid-1990s through a global analysis of Topex/Poseidon altimetry. The goal of this study is to try to estimate the parameters of this model by processing all the available VLBI observations on a global network of stations over the last 35 years performed within the framework of IVS (International VLBI Service) geodetic programs. The complexity of the problemlies in the fact that the sought-for corrections to the parameters of this model lie within 1 mm and, thus, are at the limit of their detectability by all currently available methods of ground-based positional measurements. This requires applying universal software packages with a high accuracy of reduction calculations and a well-developed system of controlling the simultaneous adjustment of observational data to analyze long series of VLBI observations. This study has been performed with the QUASAR software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences. Although the results obtained, on the whole, confirm a high accuracy of the basic model in the IERS Conventions (2010), statistically significant corrections that allow this model to be refined have been detected for some harmonics of the ERP variations.

The comparison of SRs' variation affected by solar events observed in America and in China

NASA Astrophysics Data System (ADS)

Yu, H.; Williams, E.

2017-12-01

Schumann Resonances(SRs) are the electromagnetic resonance wave propagating in the earth-ionosphere cavity. Its characteristic of propagation are modified by the variation of ionosphere. So SRs can be the tools of monitoring the ionosphere which is often perturbed by solar events, x-ray emission and some other space-weather events (Roldugin et.al., 2004, De et al., 2010; Satori et.al., 2015). In present work, the amplitude and intrinsic frequencies of SRs observed at RID station in America and YSH station in China are compared. The variation of SRs during the solar flare on Feb. 15, 2011 are analyzed. Two-Dimensional Telegraph Equation(TDTE) method is used to simulate the perturbation of ionosphere by solar proton events. From the simulation and observation, the asymmetric construction of ionoshphere which is perturbed by the solar event will affect the amplitudes and frequencies of SRs. Due to the interfere influence of forward and backward propagation of electromagnetic field, the SR amplitude on different station will present different variation. The distance among the lightning source, observer and perturbed area will produce the different variation of amplitude and frequency for different station' SR.

ERP-Variations on Time Scales Between Hours and Months Derived From GNSS Observations

NASA Astrophysics Data System (ADS)

Weber, R.; Englich, S.; Mendes Cerveira, P.

2007-05-01

Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Rotation Parameters (ERPs - polar motion, UT1/LOD) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the ERP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the year 2005. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 113 fairly stable stations out of the IGS05 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed.

Significant seasonal variations of microbial community in an acid mine drainage lake in Anhui Province, China.

PubMed

Hao, Chunbo; Wei, Pengfei; Pei, Lixin; Du, Zerui; Zhang, Yi; Lu, Yanchun; Dong, Hailiang

2017-04-01

Acid mine drainage (AMD),characterized by strong acidity and high metal concentrations, generates from the oxidative dissolution of metal sulfides, and acidophiles can accelerate the process significantly. Despite extensive research in microbial diversity and community composition, little is known about seasonal variations of microbial community structure (especially micro eukaryotes) in response to environmental conditions in AMD ecosystem. To this end, AMD samples were collected from Nanshan AMD lake, Anhui Province, China, over a full seasonal cycle from 2013 to 2014, and water chemistry and microbial composition were studied. pH of lake water was stable (∼3.0) across the sampling period, while the concentrations of ions varied dramatically. The highest metal concentrations in the lake were found for Mg and Al, not commonly found Fe. Unexpectedly, ultrahigh concentration of chlorophyll a was measured in the extremely acidic lake, reaching 226.43-280.95 μg/L in winter, even higher than those in most eutrophic freshwater lakes. Both prokaryotic and eukaryotic communities showed a strong seasonal variation. Among the prokaryotes, "Ferrovum", a chemolithotrophic iron-oxidizing bacterium was predominant in most sampling seasons, although it was a minor member prior to September, 2012. Fe 2+ was the initial geochemical factor that drove the variation of the prokaryotic community. The eukaryotic community was simple but varied more drastically than the prokaryotic community. Photoautotrophic algae (primary producers) formed a food web with protozoa or flagellate (top consumers) across all four seasons, and temperature appeared to be responsible for the observed seasonal variation. Ochromonas and Chlamydomonas (responsible for high algal bloom in winter) occurred in autumn/summer and winter/spring seasons, respectively, because of their distinct growth temperatures. The closest phylogenetic relationship between Chlamydomonas species in the lake and those in Arctic

Large-scale Observations of a Subauroral Polarization Stream by Midlatitude SuperDARN Radars: Instantaneous Longitudinal Velocity Variations

NASA Technical Reports Server (NTRS)

Clausen, L. B. N.; Baker, J. B. H.; Sazykin, S.; Ruohoniemi, J. M.; Greenwald, R. A.; Thomas, E. J.; Shepherd, S. G.; Talaat, E. R.; Bristow, W. A.; Zheng, Y.;

NO TIMING VARIATIONS OBSERVED IN THIRD TRANSIT OF SNOW-LINE EXOPLANET KEPLER-421b

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

Dalba, Paul A.; Muirhead, Philip S., E-mail: pdalba@bu.edu

2016-07-20

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model withmore » no TTVs is favored to 3.6 σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.« less

Implications of the Observed Mesoscale Variations of Clouds for Earth's Radiation Budget

NASA Technical Reports Server (NTRS)

Rossow, William B.; Delo, Carl; Cairns, Brian; Hansen, James E. (Technical Monitor)

2001-01-01

The effect of small-spatial-scale cloud variations on radiative transfer in cloudy atmospheres currently receives a lot of research attention, but the available studies are not very clear about which spatial scales are important and report a very large range of estimates of the magnitude of the effects. Also, there have been no systematic investigations of how to measure and represent these cloud variations. We exploit the cloud climatology produced by the International Satellite Cloud Climatology Project (ISCCP) to: (1) define and test different methods of representing cloud variation statistics, (2) investigate the range of spatial scales that should be included, (3) characterize cloud variations over a range of space and time scales covering mesoscale (30 - 300 km, 3-12 hr) into part of the lower part of the synoptic scale (300 - 3000 km, 1-30 days), (4) obtain a climatology of the optical thickness, emissivity and cloud top temperature variability of clouds that can be used in weather and climate GCMS, together with the parameterization proposed by Cairns et al. (1999), to account for the effects of small-scale cloud variations on radiative fluxes, and (5) evaluate the effect of observed cloud variations on Earth's radiation budget. These results lead to the formulation of a revised conceptual model of clouds for use in radiative transfer calculations in GCMS. The complete variability climatology can be obtained from the ISCCP Web site at http://isccp.giss.nasa.gov.

Significant variations in nutritional supplementation amongst neonates in the United Kingdom.

PubMed

Gordon, Morris; Isaji, Sahira; Tyacke, Fiona

2016-08-08

To ascertain United Kingdom adherence to European society of Paediatric Gastroenterology, Hepatology and Nutrition guidance (ESPGHAN). A national cross sectional questionnaire study of neonatal units across England was completed between January and March 2014. All 174 units in the country were attempted to be contacted to complete a telephone survey. This included all level 1, 2 and 3 units. They were initially contacted by phone and asking any senior member of the team about their current practice and procedures. The first ten telephone interviews were completed with two researchers present to ensure consistency of approach. If no response was received or no details were available, one further attempt was made to contact the unit. The results were recorded in a proforma and then collated and entered into a spreadsheet for analysis. Comparison to United Kingdom adherence to ESPGHAN guidance was completed. Response rate was 53%. There was variation in use of all supplements. The survey collected data from 91 neonatal units (53% response rate). It was found that 10% of neonatal units had no fixed policy on supplements. The protocols regarding supplementation involved predominantly folic acid, vitamin A, vitamin D and iron, with much variation in doses and regimens. The criteria for prescribing supplements was largely based on age (47%) with only 7% using a weight targets to initiate supplements. Summary data regarding the appropriateness of each nutritional supplement for a variety of different weights are presented, as well as comparison to ESPGHAN guidance which suggests issues with both underdoing of Breast Fed infants and overdosing of infants on several artificial formulas which already contain significant amounts of these nutritional elements. There is significant heterogeneity in neonatal policies when prescribing supplements to neonates. National policies which take international guidance into account are recommended.

On quasi-periodic variations of low-energy cosmic rays observed near earth.

PubMed

Kudela, Karel; Langer, Ronald

2015-06-01

Cosmic ray (CR) may partially, especially at high altitudes, contribute to the dosimetric characteristics. Along with irregular CR variations as Forbush decreases and solar particle events are, the quasi-periodic variations may be of some relevance too. A very short review (with references to original papers) of the present knowledge of various types of such variations is presented, namely (i) diurnal wave, (ii) ~27 d variability due to the solar rotation, (iii) Rieger-type periodicity, and (iv) quasi-biennial oscillations as well as waves on longer time scales related to solar activity and to polarity of magnetic field of the Sun. Variability is illustrated in measurements of secondary CR on the ground including the high-altitude observations at Lomnický štít. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Interannual Variation in Offshore Advection of Amazon-Orinoco Plume Waters: Observations, Forcing Mechanisms, and Impacts

NASA Astrophysics Data System (ADS)

Fournier, S.; Vandemark, D. C.; Gaultier, L.; Lee, T.; Jonsson, B. F.; Gierach, M. M.

2017-12-01

Sea surface salinity (SSS) and sea surface temperature (SST) variations in the tropical Atlantic east of the Lesser Antilles, a region impacted by freshwater advection from the Amazon and Orinoco Rivers have potential implications to late-summer tropical cyclones (TCs). This study examines these variations during late summer and their forcing mechanisms using observations. During the period 2010-2014, the largest difference in plume-affected area, defined as the extent covered by SSS lower than 35.5 pss, is found between 2011 and 2014. Plume waters covered 92% (60%) of the study region in 2011 (2014) with the averaged SSS in the study region being 2-pss lower in 2011. Lagrangian particle tracking based on satellite-derived ocean currents is used to diagnose the impacts of the river plumes on SSS and SST during 2010-2014. Northward freshwater flux in the summer of 2014 is significantly weaker than those in 2010-2013. This is not due to interannual discharge variability, but significant changes in eddy-driven transport and cross-shore winds. In particular, the stronger cross-shore wind in May 2014 restricted offshore freshwater flow, leading to a smaller extent of the plume-affected area. Persistent SST gradients are often found near the plume edge, which may have implication to ocean-atmosphere coupling associated with TC-related convection. SST in the study region is 1°C higher in 2010 than in other years, and is related to basin-scale ocean-atmosphere processes. Interannual variation in Amazon advective pathways and the associated SSS changes are also influenced by changes in the ITCZ position between 2011 and 2014.

Diurnal Variations of Dust from Mars Climate Sounder Observations: Initial Results

NASA Astrophysics Data System (ADS)

Kleinboehl, A.

2017-12-01

Over the recent years, research on the Martian atmosphere has been focusing increasingly on aerosols. One recent focus has been on detached dust layers (DDL) as they have a significant radiative impact on the atmosphere. The dust distribution in the Martian atmosphere is affected by transport processes like lifting, advection, and sedimentation. However, lifting and sedimentation processes are only poorly understood, and the formation mechanism of DDLs is unclear. Significant variations in the occurrence of DDLs have been observed in comparisons of nearly co-located daytime and nighttime dust extinction measurements by the Mars Climate Sounder (MCS). However, the detailed behavior of changes in the vertical profile of dust over the course of a day has largely been unexplored. To date, aerosol studies by MCS have been limited to observations around 3 am and 3 pm local time due to the sun-synchronous orbit of the Mars Reconnaissance Orbiter (MRO), from which MCS is operated. MCS nominally observes in the direction of the MRO orbit track. Since Sep. 2010 the MCS instrument has been performing frequent sideways scans to obtain measurements at various local times. These special measurements yield nearly global coverage while sampling local times within a few hours of the nominal local time determined by the MRO orbit track. Of particular interest is the behavior at latitudes where cross-track measurements intersect with in-track measurements such that the same airmass is sampled 3 times in intervals of 2 hours at mid-latitudes. Here I present initial analyses of dust vertical profiles retrieved from these MCS observations during the dusty season of the Martian year. Dust opacities tend to be highest within 25 km of the surface and decreasing above. Numerous sets of profiles have been identified in the southern mid-latitudes in which this dust opacity slope is lofted by several kilometers in altitude between 4 pm and 6 pm local time. The behavior is largely restricted to

The significance of microwave observations for the planets

NASA Astrophysics Data System (ADS)

de Pater, Imke

1991-01-01

A review of radio observations of the giant and terrestrial planets is presented, together with a discussion as to how our understanding of the planets' surfaces, atmospheres and magnetospheres has improved with help of these data. Giant planet atmospheres. The radio spectra and resolved images of the four giant planets are compared. Jupiter and Saturn are very much alike: NH3 gas is depleted compared to what would be expected for a solar nitrogen abundance by a factor of ~5 at P <= 1-2 bar, and enhanced by ~1.5 at P > 2 bar on Jupiter and by 3-4 at P > 4-5 bar on Saturn. Bright bands across the planetary disks imply a latitudinal variation in the precise ammonia abundance. Uranus and Neptune are very different from the former two planets, in that they exhibit a depletion of NH3 gas by about two orders of magnitude over a large altitude range in the atmosphere. Uranus shows a large pole-to-equator gradient in brightness temperature. The loss of NH3 gas in all four planetary atmospheres is most likely due to the formation of NH4SH. This requires the H,S abundance in Jupiter and Saturn to be enhanced by a factor of 6-7 and 10-15 respectively above the solar value, and in Uranus and Neptune by over two orders of magnitude. The NH3 and H2S abundances derived from radio data support the "core-instability" models on planetary formation by Pollack and Bodenheimer [1989]. The latitudinal variation in the NH3 abundance on the planets suggests differences in the location of the NH4SH cloud layers and hence the dynamics of the planets. Jupiter's synchrotron radiation. Radio observations of Jupiter's synchrotron radiation have led to a detailed model of Jupiter's inner magnetosphere with electron distributions. The satellites Thebe and Amalthea cause the electrons to be confined to the magnetic equatorial plane. Energy degradation of the electrons by dust in Jupiter's ring harden the electron spectrum considerably. A "hot spot" in Jupiter's radiation belts can partly be

Terrestrial water storage variations and surface vertical deformation derived from GPS and GRACE observations in Nepal and Himalayas

NASA Astrophysics Data System (ADS)

Pan, Y.; Shen, W.; Hwang, C.

2015-12-01

As an elastic Earth, the surface vertical deformation is in response to hydrological mass change on or near Earth's surface. The continuous GPS (CGPS) records show surface vertical deformations which are significant information to estimate the variation of terrestrial water storage. We compute the loading deformations at GPS stations based on synthetic models of seasonal water load distribution and then invert the synthetic GPS data for surface mass distribution. We use GRACE gravity observations and hydrology models to evaluate seasonal water storage variability in Nepal and Himalayas. The coherence among GPS inversion results, GRACE and hydrology models indicate that GPS can provide quantitative estimates of terrestrial water storage variations by inverting the surface deformation observations. The annual peak-to-peak surface mass change derived from GPS and GRACE results reveal seasonal loads oscillations of water, snow and ice. Meanwhile, the present uplifting of Nepal and Himalayas indicates the hydrology mass loss. This study is supported by National 973 Project China (grant Nos. 2013CB733302 and 2013CB733305), NSFC (grant Nos. 41174011, 41429401, 41210006, 41128003, 41021061).

Variations of Luzon Undercurrent from observations and numerical model simulations

NASA Astrophysics Data System (ADS)

Wang, Qingye; Zhai, Fangguo; Hu, Dunxin

2014-06-01

Significant intraseasonal variability (ISV) of about 45-80 days and seasonal variation of the Luzon Undercurrent (LUC) at 18°N are studied using direct current measurements and a high-resolution global Hybrid Coordinate Ocean Model. The variations of the LUC are vertically coherent with those of Kuroshio Current both on intraseasonal and seasonal time scales. The ISV of the LUC is dominated by eddies with diameters of about 200-300 km and extending from sea surface to intermediate layer east of Luzon Island. The LUC becomes strong (weak) when cyclonic (anticyclonic) eddies occur. The eddies east of Luzon Island mainly originate from the bifurcation point (˜13°N) of the North Equatorial Current. These eddies propagate northwestward at a typical propagation speed of about 0.16 m s-1 along the east coast of Philippines, gradually strengthen and pass the Luzon coast, and continue northward to Luzon strait. On seasonal time scale, the LUC is strong (weak) in boreal winter (summer), and this variation is related to the seasonal evolution of large-scale ocean circulation east of Philippines mainly controlled by local wind forcing.

Interannual variation of the surface temperature of tropical forests from satellite observations

DOE PAGES

Gao, Huilin; Zhang, Shuai; Fu, Rong; ...

2016-01-01

Land surface temperatures (LSTs) within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS), providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability ofmore » cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Lastly, the differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP) reanalysis data).« less

The effect of the interplanetary magnetic field on sidereal variations observed at medium depth underground detectors

NASA Technical Reports Server (NTRS)

Humble, J. E.; Fenton, A. G.

1985-01-01

It has been known for some years that the intensity variations in sidereal time observed by muon detectors at moderate underground depths are sensitive to the polarity of the interplanetary magnetic field (ipmf) near the Earth. There are differences in the response to these anisotropies as observed in the Norhtern and southern hemispheres. When fully understood, the nature of the anisotropy seems likely to provide information on the 3-dimensional structure of the heliomagnetosphere, its time variations, and its linking with the local interstellar field. The summation harmonic dials for the sidereal diurnal variation during 1958 to 1982 show that there is a strong dependence on whether the ipmf near the Earth is directed outwards from the Sun or inwards it.

Intra-plant floral variation in Cleome viscosa L. and its possible significance in breeding system.

PubMed

Saroop, Shveta; Kaul, Veenu

2015-07-01

Cleome viscosa L., an annual rainy season weed, is cosmopolitan in distribution. Two naturally growing populations of C. viscosa from Jammu, J & K, India have been studied for floral variation at an intra-plant level and its possible role in its life cycle. Plants of both the populations bear flowers which exhibit tremendous intra-plant variation in size (large and small) and sex (hermaphrodite, staminate and pistillate). The average number of flowers per plant varied significantly and so did their structural and functional details. Greater propensity, however, was towards hermaphroditism at both plant and flower levels. The large and small sized flowers differed in their morphology and reproductive features; the former were significantly larger than the latter. Anthesis, anther dehiscence and stigma receptivity were coupled in all flower types. This functional aspect along with the structural proximity between stamens at two lengths and pistil further facilitated self-pollination. However, conspicuous floral display attracted diverse pollinator fauna (Apis dorsata, Halictus albescens, Nomia curvipes and N. elliotii) which in turn mediated cross pollination. Nevertheless, each floral type contributed towards plant's fitness in its own way. Hermaphrodite flowers exhibited both self and cross pollination and assured survival by setting fruits and seeds with the large sized counterparts more productive. All these floral variations seemed to impart flexibility to the pollination system and provide fitness over the short flowering season.

High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

PubMed Central

Wei, Erhu; Jin, Shuanggen; Wan, Lihua; Liu, Wenjie; Yang, Yali; Hu, Zhenghong

2015-01-01

The Earth's rotation undergoes changes with the influence of geophysical factors, such as Earth's surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP) are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations) and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS), Global Navigation Satellite System (GLONASS), and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas) in Polar Motion (PM) and 0.5 milli-seconds (ms) in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM) and hydrological angular momentum (HAM), which needs more detailed analysis with more geophysical data in the future. PMID:25635416

CLASP/SJ Observations of Rapid Time Variations in the Ly α Emission in a Solar Active Region

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

Ishikawa, Shin-nosuke; Kubo, Masahito; Katsukawa, Yukio

The Chromospheric Ly α SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on 2015 September 3 to investigate the solar chromosphere and transition region. The slit-jaw (SJ) optical system captured Ly α images with a high time cadence of 0.6 s. From the CLASP/SJ observations, many variations in the solar chromosphere and transition region emission with a timescale of <1 minute were discovered. In this paper, we focus on the active region within the SJ field of view and investigate the relationship between short (<30 s) temporal variations in the Ly α emission and the coronal structures observed by Solarmore » Dynamics Observatory/Atmospheric Imaging Assembly (AIA). We compare the Ly α temporal variations at the coronal loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å (≈0.6 MK) channels with those in the regions with bright Ly α features without a clear association with the coronal loop footpoints. We find more short (<30 s) temporal variations in the Ly α intensity in the footpoint regions. Those variations did not depend on the temperature of the coronal loops. Therefore, the temporal variations in the Ly α intensity at this timescale range could be related to the heating of the coronal structures up to temperatures around the sensitivity peak of 171 Å. No signature was found to support the scenario that these Ly α intensity variations were related to the nanoflares. Waves or jets from the lower layers (lower chromosphere or photosphere) are possible causes for this phenomenon.« less

Cosmic ray sidereal diurnal variation of galactic origin observed by neutron monitors

NASA Technical Reports Server (NTRS)

Ishida, Y.; Nagashima, K.; Mori, S.; Morishita, I.

1985-01-01

Cosmic ray sidereal diurnal variations observed by neutron monitors are analyzed for the period 1961 to 1978, by adding 134 station years data to the previous paper (Nagashima, et al., 1983). Also the dependence of the sidereal variations on Sun's polar magnetic field polarity is examined for two periods; the period of negative polarity in the northern region, 1961 to 1969 and the period of positive polarity, 1970 to 1978. It is obtained that for the former period, the amplitude A=0.0203 + or 0.0020% and the phase phi=6.1 + or - 0.4 h LST and for the latter period, 0.0020% and phi=8.6 + or - 4 h LST, respectively.

Secular gravity variation at Svalbard (Norway) from ground observations and GRACE satellite data

NASA Astrophysics Data System (ADS)

Mémin, A.; Rogister, Y.; Hinderer, J.; Omang, O. C.; Luck, B.

2011-03-01

The Svalbard archipelago, Norway, is affected by both the present-day ice melting (PDIM) and Glacial Isostatic Adjustment (GIA) subsequent to the Last Pleistocene deglaciation. The induced deformation of the Earth is observed by using different techniques. At the Geodetic Observatory in Ny-Ålesund, precise positioning measurements have been collected since 1991, a superconducting gravimeter (SG) has been installed in 1999, and six campaigns of absolute gravity (AG) measurements were performed between 1998 and 2007. Moreover, the Gravity Recovery and Climate Experiment (GRACE) satellite mission provides the time variation of the Earth gravity field since 2002. The goal of this paper is to estimate the present rate of ice melting by combining geodetic observations of the gravity variation and uplift rate with geophysical modelling of both the GIA and Earth's response to the PDIM. We estimate the secular gravity variation by superimposing the SG series with the six AG measurements. We collect published estimates of the vertical velocity based on GPS and VLBI data. We analyse the GRACE solutions provided by three groups (CSR, GFZ, GRGS). The crux of the problem lies in the separation of the contributions from the GIA and PDIM to the Earth's deformation. To account for the GIA, we compute the response of viscoelastic Earth models having different radial structures of mantle viscosity to the deglaciation histories included in the models ICE-3G or ICE-5G. To account for the effect of PDIM, we compute the deformation of an elastic Earth model for six models of ice-melting extension and rates. Errors in the gravity variation and vertical velocity are estimated by taking into account the measurement uncertainties and the variability of the GRACE solutions and GIA and PDIM models. The ground observations agree with models that involve a current ice loss of 25 km3 water equivalent yr-1 over Svalbard, whereas the space observations give a value in the interval [5, 18] km3

Atmospheric radioactivity of Cs-134/137 observed at Namie, Fukushima: seasonal variation and contribution of biological re-suspension.

NASA Astrophysics Data System (ADS)

Kita, K.

2015-12-01

Radionuclides emitted by the accident in Fukushima dai-ichi nuclear power plant (FNDPP) have been deposited on the soil, ocean and vegetation. Even after about 4 years since the FNDPP accident significant activities of the radionuclides have been observed over severely contaminated areas. Re-suspension of radioactive cesium from the soil and vegetation to the atmosphere has been one of significant paths for its diffusion after the accident. Although the quantitative understanding of the re-suspensions is important for the prediction of future transition of radionuclides, its mechanism, identification of aerosol species which bring radioactive cesium, and the resuspension flux have not been understood in Fukushima. 　We are continuously measuring atmospheric concentration of Cs-134/137 radioactivity at Tsushima, Namie-town, located about 30km northwest from FNDPP with high-volume air samplers. It showed clear seasonal variation: it increase from April to June, and decreased from September to December. In winter and spring, it was weakly but positively correlated with the surface wind speed. On the contrary, it did not depend on the wind speed in summer and autumn. It also has different diurnal variation: higher activities were observed in daytime in winter/spring, while the activities were obviously higher in nighttime in summer/autumn. The size distribution of aerosols contributing to the Cs-134/137 re-suspension has been measured using cascade impactors attached with high-volume air samplers, and it also shows different features in winter/spring and summer/autumn. These results indicate that the mechanism of the Cs-134/137 re-suspension is different with the season in Fukushima. Scanning electron microscope observation showed that most of suspended coarse particles were soil particles in spring and biogenic particles in autumn. Details on the Cs-134/137 re-suspension mechanisms revealed by our observations and contribution of biogenic emission will be presented

Tidal and seasonal variations in calving flux observed with passive seismology

USGS Publications Warehouse

Bartholomaus, T.C.; Larsen, Christopher F.; West, Michael E.; O'Neel, Shad; Pettit, Erin C.; Truffer, Martin

2015-01-01

The seismic signatures of calving events, i.e., calving icequakes, offer an opportunity to examine calving variability with greater precision than is available with other methods. Here using observations from Yahtse Glacier, Alaska, we describe methods to detect, locate, and characterize calving icequakes. We combine these icequake records with a coincident, manually generated record of observed calving events to develop and validate a statistical model through which we can infer iceberg sizes from the properties of calving icequakes. We find that the icequake duration is the single most significant predictor of an iceberg's size. We then apply this model to 18 months of seismic recordings and find elevated iceberg calving flux during the summer and fall and a pronounced lull in calving during midwinter. Calving flux is sensitive to semidiurnal tidal stage. Large calving events are tens of percent more likely during falling and low tides than during rising and high tides, consistent with a view that deeper water has a stabilizing influence on glacier termini. Multiple factors affect the occurrence of mechanical fractures that ultimately lead to iceberg calving. At Yahtse Glacier, seismology allows us to demonstrate that variations in the rate of submarine melt are a dominant control on iceberg calving rates at seasonal timescales. On hourly to daily timescales, tidal modulation of the normal stress against the glacier terminus reveals the nonlinear glacier response to changes in the near-terminus stress field.

The role of ensemble-based statistics in variational assimilation of cloud-affected observations from infrared imagers

NASA Astrophysics Data System (ADS)

Hacker, Joshua; Vandenberghe, Francois; Jung, Byoung-Jo; Snyder, Chris

2017-04-01

Effective assimilation of cloud-affected radiance observations from space-borne imagers, with the aim of improving cloud analysis and forecasting, has proven to be difficult. Large observation biases, nonlinear observation operators, and non-Gaussian innovation statistics present many challenges. Ensemble-variational data assimilation (EnVar) systems offer the benefits of flow-dependent background error statistics from an ensemble, and the ability of variational minimization to handle nonlinearity. The specific benefits of ensemble statistics, relative to static background errors more commonly used in variational systems, have not been quantified for the problem of assimilating cloudy radiances. A simple experiment framework is constructed with a regional NWP model and operational variational data assimilation system, to provide the basis understanding the importance of ensemble statistics in cloudy radiance assimilation. Restricting the observations to those corresponding to clouds in the background forecast leads to innovations that are more Gaussian. The number of large innovations is reduced compared to the more general case of all observations, but not eliminated. The Huber norm is investigated to handle the fat tails of the distributions, and allow more observations to be assimilated without the need for strict background checks that eliminate them. Comparing assimilation using only ensemble background error statistics with assimilation using only static background error statistics elucidates the importance of the ensemble statistics. Although the cost functions in both experiments converge to similar values after sufficient outer-loop iterations, the resulting cloud water, ice, and snow content are greater in the ensemble-based analysis. The subsequent forecasts from the ensemble-based analysis also retain more condensed water species, indicating that the local environment is more supportive of clouds. In this presentation we provide details that explain the

Seasonal variation of the underground cosmic muon flux observed at Daya Bay

NASA Astrophysics Data System (ADS)

An, F. P.; Balantekin, A. B.; Band, H. R.; Bishai, M.; Blyth, S.; Cao, D.; Cao, G. F.; Cao, J.; Chan, Y. L.; Chang, J. F.; Chang, Y.; Chen, H. S.; Chen, Q. Y.; Chen, S. M.; Chen, Y. X.; Chen, Y.; Cheng, J.; Cheng, Z. K.; Cherwinka, J. J.; Chu, M. C.; Chukanov, A.; Cummings, J. P.; Ding, Y. Y.; Diwan, M. V.; Dolgareva, M.; Dove, J.; Dwyer, D. A.; Edwards, W. R.; Gill, R.; Gonchar, M.; Gong, G. H.; Gong, H.; Grassi, M.; Gu, W. Q.; Guo, L.; Guo, X. H.; Guo, Y. H.; Guo, Z.; Hackenburg, R. W.; Hans, S.; He, M.; Heeger, K. M.; Heng, Y. K.; Higuera, A.; Hsiung, Y. B.; Hu, B. Z.; Hu, T.; Huang, E. C.; Huang, H. X.; Huang, X. T.; Huber, P.; Huo, W.; Hussain, G.; Jaffe, D. E.; Jen, K. L.; Jetter, S.; Ji, X. P.; Ji, X. L.; Jiao, J. B.; Johnson, R. A.; Jones, D.; Kang, L.; Kettell, S. H.; Khan, A.; Kohn, S.; Kramer, M.; Kwan, K. K.; Kwok, M. W.; Kwok, T.; Langford, T. J.; Lau, K.; Lebanowski, L.; Lee, J.; Lee, J. H. C.; Lei, R. T.; Leitner, R.; Li, C.; Li, D. J.; Li, F.; Li, G. S.; Li, Q. J.; Li, S.; Li, S. C.; Li, W. D.; Li, X. N.; Li, X. Q.; Li, Y. F.; Li, Z. B.; Liang, H.; Lin, C. J.; Lin, G. L.; Lin, S.; Lin, S. K.; Lin, Y.-C.; Ling, J. J.; Link, J. M.; Littenberg, L.; Littlejohn, B. R.; Liu, J. L.; Liu, J. C.; Loh, C. W.; Lu, C.; Lu, H. Q.; Lu, J. S.; Luk, K. B.; Ma, X. Y.; Ma, X. B.; Ma, Y. Q.; Malyshkin, Y.; Martinez Caicedo, D. A.; McDonald, K. T.; McKeown, R. D.; Mitchell, I.; Nakajima, Y.; Napolitano, J.; Naumov, D.; Naumova, E.; Ngai, H. Y.; Ochoa-Ricoux, J. P.; Olshevskiy, A.; Pan, H.-R.; Park, J.; Patton, S.; Pec, V.; Peng, J. C.; Pinsky, L.; Pun, C. S. J.; Qi, F. Z.; Qi, M.; Qian, X.; Qiu, R. M.; Raper, N.; Ren, J.; Rosero, R.; Roskovec, B.; Ruan, X. C.; Sebastiani, C.; Steiner, H.; Sun, J. L.; Tang, W.; Taychenachev, D.; Treskov, K.; Tsang, K. V.; Tull, C. E.; Viaux, N.; Viren, B.; Vorobel, V.; Wang, C. H.; Wang, M.; Wang, N. Y.; Wang, R. G.; Wang, W.; Wang, X.; Wang, Y. F.; Wang, Z.; Wang, Z.; Wang, Z. M.; Wei, H. Y.; Wen, L. J.; Whisnant, K.; White, C. G.; Whitehead, L.; Wise, T.; Wong, H. L. H.; Wong, S. C. F.; Worcester, E.; Wu, C.-H.; Wu, Q.; Wu, W. J.; Xia, D. M.; Xia, J. K.; Xing, Z. Z.; Xu, J. L.; Xu, Y.; Xue, T.; Yang, C. G.; Yang, H.; Yang, L.; Yang, M. S.; Yang, M. T.; Yang, Y. Z.; Ye, M.; Ye, Z.; Yeh, M.; Young, B. L.; Yu, Z. Y.; Zeng, S.; Zhan, L.; Zhang, C.; Zhang, C. C.; Zhang, H. H.; Zhang, J. W.; Zhang, Q. M.; Zhang, X. T.; Zhang, Y. M.; Zhang, Y. X.; Zhang, Y. M.; Zhang, Z. J.; Zhang, Z. Y.; Zhang, Z. P.; Zhao, J.; Zhou, L.; Zhuang, H. L.; Zou, J. H.

2018-01-01

The Daya Bay Experiment consists of eight identically designed detectors located in three underground experimental halls named as EH1, EH2, EH3, with 250, 265 and 860 meters of water equivalent vertical overburden, respectively. Cosmic muon events have been recorded over a two-year period. The underground muon rate is observed to be positively correlated with the effective atmospheric temperature and to follow a seasonal modulation pattern. The correlation coefficient α, describing how a variation in the muon rate relates to a variation in the effective atmospheric temperature, is found to be αEH1 = 0.362±0.031, αEH2 = 0.433±0.038 and αEH3 = 0.641±0.057 for each experimental hall.

Using GIA observables to constrain the thermal contribution to lateral variations in mantle viscosity

NASA Astrophysics Data System (ADS)

Wu, P.; Wang, H.; van der Wal, W.; Shum, C.; Lee, H.; Braun, A.

2009-05-01

Lateral heterogeneities in the mantle can be caused by thermal, chemical and non-isotropic pre-stress effects. Here, observations of the glacial isostatic adjustment (GIA) process are used to constrain the thermal contribution to lateral variations in upper and lower mantle viscosities. The Coupled Laplace-Finite Element method is used to predict the GIA response on a spherical, self-gravitating, compressible, viscoelastic earth with self-gravitating oceans, induced by either the ICE-5G or ICE-4G deglaciation models. GIA observations include global historic relative sea level data, GPS uplift rates in Laurentide and Fennoscandia, altimetry together with tide-gauge data in the Great Lakes area, and GRACE data in Laurentide. The lateral viscosity perturbations are inferred from the high resolution seismic tomography model of Grand (2002) by using a conversion relation that takes into account both anelastic and anharmonic effects (Karato 2008). To determine the contribution of thermal effects in the upper and lower mantle, the scaling factor b is also inserted into the conversion relation: For b = 1, lateral velocity variations are caused by thermal effects alone; while b < 1 indicates a decreasing contribution of thermal effects; eventually when b = 0, there is no lateral viscosity variations exist and the Earth is laterally homogeneous. The value of b in the upper mantle is b1 while that in the lower mantle is b2. The lateral viscosity variations computed this way are superposed on a reference model that is able to give a reasonably good fit to the GIA observations. The parameter space for (b1, b2) is then searched to find the combination that yields the best improvement in fitting the GIA data in Laurentide, Fennoscandia or globally.

Evaluation of the impact of observations on blended sea surface winds in a two-dimensional variational scheme using degrees of freedom

NASA Astrophysics Data System (ADS)

Wang, Ting; Xiang, Jie; Fei, Jianfang; Wang, Yi; Liu, Chunxia; Li, Yuanxiang

2017-12-01

This paper presents an evaluation of the observational impacts on blended sea surface winds from a two-dimensional variational data assimilation (2D-Var) scheme. We begin by briefly introducing the analysis sensitivity with respect to observations in variational data assimilation systems and its relationship with the degrees of freedom for signal (DFS), and then the DFS concept is applied to the 2D-Var sea surface wind blending scheme. Two methods, a priori and a posteriori, are used to estimate the DFS of the zonal ( u) and meridional ( v) components of winds in the 2D-Var blending scheme. The a posteriori method can obtain almost the same results as the a priori method. Because only by-products of the blending scheme are used for the a posteriori method, the computation time is reduced significantly. The magnitude of the DFS is critically related to the observational and background error statistics. Changing the observational and background error variances can affect the DFS value. Because the observation error variances are assumed to be uniform, the observational influence at each observational location is related to the background error variance, and the observations located at the place where there are larger background error variances have larger influences. The average observational influence of u and v with respect to the analysis is about 40%, implying that the background influence with respect to the analysis is about 60%.

Satellite microwave observations of soil moisture variations. [by the microwave radiometer on the Nimbus 5 satellite

NASA Technical Reports Server (NTRS)

Schmugge, T. J.; Rango, A.; Neff, R.

1975-01-01

The electrically scanning microwave radiometer (ESMR) on the Nimbus 5 satellite was used to observe microwave emissions from vegetated and soil surfaces over an Illinois-Indiana study area, the Mississippi Valley, and the Great Salt Lake Desert in Utah. Analysis of microwave brightness temperatures (T sub B) and antecedent rainfall over these areas provided a way to monitor variations of near-surface soil moisture. Because vegetation absorbs microwave emission from the soil at the 1.55 cm wavelength of ESMR, relative soil moisture measurements can only be obtained over bare or sparsely vegetated soil. In general T sub B increased during rainfree periods as evaporation of water and drying of the surface soil occurs, and drops in T sub B are experienced after significant rainfall events wet the soil. Microwave observations from space are limited to coarse resolutions (10-25 km), but it may be possible in regions with sparse vegetation cover to estimate soil moisture conditions on a watershed or agricultural district basis, particularly since daily observations can be obtained.

Diurnal variations in optical depth at Mars: Observations and interpretations

NASA Technical Reports Server (NTRS)

Colburn, D. S.; Pollack, J. B.; Haberle, R. M.

1988-01-01

Viking lander camera images of the Sun were used to compute atmospheric optical depth at two sites over a period of 1 to 1/3 martian years. The complete set of 1044 optical depth determinations is presented in graphical and tabular form. Error estimates are presented in detail. Optical depths in the morning (AM) are generally larger than in the afternoon (PM). The AM-PM differences are ascribed to condensation of water vapor into atmospheric ice aerosols at night and their evaporation in midday. A smoothed time series of these differences shows several seasonal peaks. These are simulated using a one-dimensional radiative convective model which predicts martial atmospheric temperature profiles. A calculation combining these profiles with water vapor measurements from the Mars Atmospheric Water Detector is used to predict when the diurnal variations of water condensation should occur. The model reproduces a majority of the observed peaks and shows the factors influencing the process. Diurnal variation of condensation is shown to peak when the latitude and season combine to warm the atmosphere to the optimum temperature, cool enough to condense vapor at night and warm enough to cause evaporation at midday.

Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties

NASA Astrophysics Data System (ADS)

Bastianelli, Carole; Ali, Adam A.; Beguin, Julien; Bergeron, Yves; Grondin, Pierre; Hély, Christelle; Paré, David

2017-07-01

At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW) are spreading southward at the expense of more productive closed-canopy black spruce-moss forests (MF). The objective of this study was to investigate whether soil properties could distinguish MF from LW in the transition zone where both ecosystem types coexist. This study brings out clear evidence that differences in vegetation cover can lead to significant variations in soil physical and geochemical properties.Here, we showed that soil carbon, exchangeable cations, and iron and aluminium crystallinity vary between boreal closed-canopy forests and open lichen woodlands, likely attributed to variations in soil microclimatic conditions. All the soils studied were typical podzolic soil profiles evolved from glacial till deposits that shared a similar texture of the C layer. However, soil humus and the B layer varied in thickness and chemistry between the two forest ecosystems at the pedon scale. Multivariate analyses of variance were used to evaluate how soil properties could help distinguish the two types at the site scale. MF humus (FH horizons horizons composing the O layer) showed significantly higher concentrations of organic carbon and nitrogen and of the main exchangeable base cations (Ca, Mg) than LW soils. The B horizon of LW sites held higher concentrations of total Al and Fe oxides and particularly greater concentrations of inorganic amorphous Fe oxides than MF mineral soils, while showing a thinner B layer. Overall, our results show that MF store three times more organic carbon in their soils (B+FH horizons, roots apart) than LW. We suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the vegetation structure (stand density

Time variations in the mechanical characteristics of local crustal segments according to seismic observations

NASA Astrophysics Data System (ADS)

Kocharyan, G. G.; Gamburtseva, N. G.; Sanina, I. A.; Danilova, T. V.; Nesterkina, M. A.; Gorbunova, E. M.; Ivanchenko, G. N.

2011-04-01

The results of the seismic observations made with two different experimental setups are presented. In the first case, the signals produced by underground nuclear explosions at the Semipalatinsk Test Site were measured on a linear profile, which allowed one to definitely outline the areas where the mechanical properties of rocks experienced considerable time variations. In the second case, the waves excited by the open-pit mine blasts recorded at a small-aperture seismic array at the Mikhnevo Geophysical Station (Institute of Geosphere Dynamics, Russian Academy of Sciences) on the East European Platform favored the estimation of variations in the integral characteristics of the seismic path. Measurements in aseismic regions characterized by diverse geological structure and different tectonic conditions revealed similar effects of the strong dependency of seismic parameters on the time of explosions. Here, the variations experienced by the maximum amplitudes of oscillations and irrelevant to seasonal changes or local conditions reached a factor of two. The generic periods of these variations including the distinct annual rhythm are probably the fragments of a lower-frequency process. The obtained results suggest that these variations are due to changes in the stressstrain state of active fault zones, which, in turn, can be associated with the macroscale motion of large blocks triggered by tidal strains, tectonic forces and, possibly, variations in the rate of the Earth's rotation.

Spatiotemporal variation in the postseismic deformation of the 2011 Tohoku-oki earthquake revealed by seafloor geodetic observations

NASA Astrophysics Data System (ADS)

Tomita, F.; Kido, M.; Ohta, Y.; Hino, R.; Iinuma, T.

2016-12-01

Postseismic deformation following the 2011 Tohoku-oki earthquake has been detected by on- and off-shore geodetic observations. GPS/Acoustic (GPS/A) observations [Watanabe et al., 2014, GRL] just above the coseismic primary rupture area (PRA) show significant landward movement in contrast to the trench-ward movement of the on-shore GPS observations, which can be generally explained by viscoelastic relaxation [Sun et al., 2014, Nature]. Furthermore, Tomita et al. [2015, AGU] demonstrated along-trench variation of the postseismic deformation also using GPS/A observations. In this study, we show detailed spatiotemporal characteristics of the postseismic deformation using updated GPS/A measurement results. We employed 20 GPS/A sites located in Tohoku-oki region and had conducted repeated campaign surveys from Sep. 2012 to May 2016. GPS/A positioning was performed using the method of Kido et al. [2006, EPS]. Then, we calculated postseismic displacement rates by applying a weighted robust linear fitting. The updated results of the postseismic displacement rates are consistent with the characteristic revealed by Tomita et al. [2015] but are estimated with better precision ( 2 cm/yr in 1σ). The sites in the north region of PRA show slight trenchward movement (< 5 cm/yr), while the sites in the south region of PRA show significant trenchward movement (5-15 cm/yr) indicating dominance of the afterslip effects. Moreover, the sites above PRA show significant landward movement (10-15 cm/yr) indicating viscoelastic relaxation and interplate relocking effects. Furthermore, the updated results may show temporal decay of afterslip; the temporally decaying displacements have been observed in the south region of PRA. However, such a temporal decay has not been measured in the region where viscoelastic relaxation causes significant deformation. In the presentation, we will discuss detail spatiotemporal evolution of the postseismic deformation processes from the updated results by

From symmetry to asymmetry: Phylogenetic patterns of asymmetry variation in animals and their evolutionary significance

PubMed Central

Palmer, A. Richard

1996-01-01

Phylogenetic analyses of asymmetry variation offer a powerful tool for exploring the interplay between ontogeny and evolution because (i) conspicuous asymmetries exist in many higher metazoans with widely varying modes of development, (ii) patterns of bilateral variation within species may identify genetically and environmentally triggered asymmetries, and (iii) asymmetries arising at different times during development may be more sensitive to internal cytoplasmic inhomogeneities compared to external environmental stimuli. Using four broadly comparable asymmetry states (symmetry, antisymmetry, dextral, and sinistral), and two stages at which asymmetry appears developmentally (larval and postlarval), I evaluated relations between ontogenetic and phylogenetic patterns of asymmetry variation. Among 140 inferred phylogenetic transitions between asymmetry states, recorded from 11 classes in five phyla, directional asymmetry (dextral or sinistral) evolved directly from symmetrical ancestors proportionally more frequently among larval asymmetries. In contrast, antisymmetry, either as an end state or as a transitional stage preceding directional asymmetry, was confined primarily to postlarval asymmetries. The ontogenetic origin of asymmetry thus significantly influences its subsequent evolution. Furthermore, because antisymmetry typically signals an environmentally triggered asymmetry, the phylogenetic transition from antisymmetry to directional asymmetry suggests that many cases of laterally fixed asymmetries evolved via genetic assimilation. PMID:8962039

SABER (TIMED) and MLS (UARS) Temperature Observations of Mesospheric and Stratospheric QBO and Related Tidal Variations

NASA Technical Reports Server (NTRS)

Huang, Frank T.; Mayr, Hans G.; Reber, Carl A.; Russell, James; Mlynczak, Marty; Mengel, John

2006-01-01

More than three years of temperature observations from the SABER (TIMED) and MLS WARS) instruments are analyzed to study the annual and inter-annual variations extending from the stratosphere into the upper mesosphere. The SABER measurements provide data from a wide altitude range (15 to 95 km) for the years 2002 to 2004, while the MLS data were taken in the 16 to 55 km altitude range a decade earlier. Because of the sampling properties of SABER and MLS, the variations with local solar time must be accounted for when estimating the zonal mean variations. An algorithm is thus applied that delineates with Fourier analysis the year-long variations of the migrating tides and zonal mean component. The amplitude of the diurnal tide near the equator shows a strong semiannual periodicity with maxima near equinox, which vary from year to year to indicate the influence from the Quasi-biennial Oscillation (QBO) in the zonal circulation. The zonal mean QBO temperature variations are analyzed over a range of latitudes and altitudes, and the results are presented for latitudes from 48"s to 48"N. New results are obtained for the QBO, especially in the upper stratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes, the QBO amplitudes show local peaks, albeit small, that occur at different altitudes. From about 20 to 40 km, and within about 15" of the Equator, the amplitudes can approach 3S K for the stratospheric QBO or SQBO. For the mesospheric QBO or MQBO, we find peaks near 70 km, with temperature amplitudes reaching 3.5"K, and near 85 km, the amplitudes approach 2.5OK. Morphologically, the amplitude and phase variations derived from the SABER and MLS measurements are in qualitative agreement. The QBO amplitudes tend to peak at the Equator but then increase again pole-ward of about 15" to 20'. The phase progression with altitude varies more gradually at the Equator than at mid-latitudes. A comparison of the observations with results from the Numerical Spectral

Diurnal observations of HCl altitude variation in the 70-100 km mesosphere of Venus

NASA Astrophysics Data System (ADS)

Sandor, Brad J.; Todd Clancy, R.

2017-07-01

First submm spectroscopic observations of the 625.9 GHz H35Cl absorption lines of the Venus dayside atmosphere were obtained with the James Clerk Maxwell Telescope (JCMT) on March 2, 2013. These data, which support retrieval of HCl altitude distributions in the Venus mesosphere (70-100 km), are presented here and compared with previously reported JCMT observations of Venus nightside HCl (Sandor et al., 2012). The measured dayside profile agrees with that of the nightside, indicating no diurnal variation is present. More specifically, the nightside spectra revealed a secular decrease of upper mesospheric HCl between observations one month apart, at fixed latitude and local time. The dayside profile reported here presents upper mesospheric abundances that are bracketed by the two previously measured nightside profiles, indicating that if diurnal variation is present, it must be weaker than the secular variations occurring at fixed local time. The previous study, which measured nightside HCl abundances above 85 km to be much smaller than predicted from photochemical modeling, suggested a dynamical explanation for the disagreement wherein nightside downwelling associated with the SubSolar to AntiSolar (SSAS) atmospheric circulation might suppress upper mesospheric abundances predicted purely from photochemistry. However a straightforward prediction from the proposed mechanism is that HCl abundance on the dayside, where the SSAS drives upward rather than downward transport should at least agree with, and perhaps exceed that of the photochemical model. The finding that dayside HCl abundance agrees with that of the nightside, hence also is much smaller than that of the model shows the SSAS hypothesis to be incorrect.

Dissecting the IRX-β dust attenuation relation: exploring the physical origin of observed variations in galaxies

NASA Astrophysics Data System (ADS)

Popping, Gergö; Puglisi, Annagrazia; Norman, Colin A.

2017-12-01

The use of ultraviolet (UV) emission as a tracer of galaxy star formation rate (SFR) is hampered by dust obscuration. The empirical relationship between UV-slope, β, and the ratio between far-infrared and UV luminosity, IRX, is commonly employed to account for obscured UV emission. We present a simple model that explores the physical origin of variations in the IRX-β dust attenuation relation. A relative increase in FUV compared to NUV attenuation and an increasing stellar population age cause variations towards red UV-slopes for a fixed IRX. Dust geometry effects (turbulence, dust screen with holes, mixing of stars within the dust screen, two-component dust model) cause variations towards blue UV-slopes. Poor photometric sampling of the UV spectrum causes additional observational variations. We provide an analytic approximation for the IRX-β relation invoking a subset of the explored physical processes (dust type, stellar population age, turbulence). We discuss observed variations in the IRX-β relation for local (sub-galactic scales) and high-redshift (normal and dusty star-forming galaxies, galaxies during the epoch of reionization) galaxies in the context of the physical processes explored in our model. High spatial resolution imaging of the UV and sub-mm emission of galaxies can constrain the IRX-β dust attenuation relation for different galaxy types at different epochs, where different processes causing variations may dominate. These constraints will allow the use of the IRX-β relation to estimate intrinsic SFRs of galaxies, despite the lack of a universal relation.

Observed solar near UV variability: A contribution to variations of the solar constant

NASA Technical Reports Server (NTRS)

London, Julius; Pap, Judit; Rottman, Gary J.

1989-01-01

Continuous Measurements of the Solar UV have been made by an instrument on the Solar Mesosphere Explorer (SME) since October 1981. The results for the wavelength interval 200 to 300 nm show an irradiance decrease to a minimum in early 1987 and a subsequent increase to mid-April 1989. The observed UV changes during part of solar cycles 21 to 22 represent approx. 35 percent (during the decreasing phase) and 25 percent (during the increasing phase) of the observed variations of the solar constant for the same time period as the SME measurements.

Investigating common coding of observed and executed actions in the monkey brain using cross-modal multi-variate fMRI classification.

PubMed

Fiave, Prosper Agbesi; Sharma, Saloni; Jastorff, Jan; Nelissen, Koen

2018-05-19

Mirror neurons are generally described as a neural substrate hosting shared representations of actions, by simulating or 'mirroring' the actions of others onto the observer's own motor system. Since single neuron recordings are rarely feasible in humans, it has been argued that cross-modal multi-variate pattern analysis (MVPA) of non-invasive fMRI data is a suitable technique to investigate common coding of observed and executed actions, allowing researchers to infer the presence of mirror neurons in the human brain. In an effort to close the gap between monkey electrophysiology and human fMRI data with respect to the mirror neuron system, here we tested this proposal for the first time in the monkey. Rhesus monkeys either performed reach-and-grasp or reach-and-touch motor acts with their right hand in the dark or observed videos of human actors performing similar motor acts. Unimodal decoding showed that both executed or observed motor acts could be decoded from numerous brain regions. Specific portions of rostral parietal, premotor and motor cortices, previously shown to house mirror neurons, in addition to somatosensory regions, yielded significant asymmetric action-specific cross-modal decoding. These results validate the use of cross-modal multi-variate fMRI analyses to probe the representations of own and others' actions in the primate brain and support the proposed mapping of others' actions onto the observer's own motor cortices. Copyright © 2018 Elsevier Inc. All rights reserved.

Reliability of mercury-in-silastic strain gauge plethysmography curve reading: influence of clinical clues and observer variation.

PubMed

Høyer, Christian; Pavar, Susanne; Pedersen, Begitte H; Biurrun Manresa, José A; Petersen, Lars J

2013-08-01

Mercury-in-silastic strain gauge pletysmography (SGP) is a well-established technique for blood flow and blood pressure measurements. The aim of this study was to examine (i) the possible influence of clinical clues, e.g. the presence of wounds and color changes during blood pressure measurements, and (ii) intra- and inter-observer variation of curve interpretation for segmental blood pressure measurements. A total of 204 patients with known or suspected peripheral arterial disease (PAD) were included in a diagnostic accuracy trial. Toe and ankle pressures were measured in both limbs, and primary observers analyzed a total of 804 pressure curve sets. The SGP curves were later reanalyzed separately by two observers blinded to clinical clues. Intra- and inter-observer agreement was quantified using Cohen's kappa and reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland-Altman analysis. There was an overall agreement regarding patient diagnostic classification (PAD/not PAD) in 202/204 (99.0%) for intra-observer (κ = 0.969, p < 0.001), and 201/204 (98.5%) for inter-observer readings (κ = 0.953, p < 0.001). Reliability analysis showed excellent correlation between blinded versus non-blinded and inter-observer readings for determination of absolute segmental pressures (all intraclass correlation coefficients ≥ 0.984). The coefficient of variance for determination of absolute segmental blood pressure ranged from 2.9-3.4% for blinded/non-blinded data and from 3.8-5.0% for inter-observer data. This study shows a low inter-observer variation among experienced laboratory technicians for reading strain gauge curves. The low variation between blinded/non-blinded readings indicates that SGP measurements are minimally biased by clinical clues.

Reliability of laser Doppler flowmetry curve reading for measurement of toe and ankle pressures: intra- and inter-observer variation.

PubMed

Høyer, C; Paludan, J P D; Pavar, S; Biurrun Manresa, J A; Petersen, L J

2014-03-01

To assess the intra- and inter-observer variation in laser Doppler flowmetry curve reading for measurement of toe and ankle pressures. A prospective single blinded diagnostic accuracy study was conducted on 200 patients with known or suspected peripheral arterial disease (PAD), with a total of 760 curve sets produced. The first curve reading for this study was performed by laboratory technologists blinded to clinical clues and previous readings at least 3 months after the primary data sampling. The pressure curves were later reassessed following another period of at least 3 months. Observer agreement in diagnostic classification according to TASC-II criteria was quantified using Cohen's kappa. Reliability was quantified using intra-class correlation coefficients, coefficients of variance, and Bland-Altman analysis. The overall agreement in diagnostic classification (PAD/not PAD) was 173/200 (87%) for intra-observer (κ = .858) and 175/200 (88%) for inter-observer data (κ = .787). Reliability analysis confirmed excellent correlation for both intra- and inter-observer data (ICC all ≥.931). The coefficients of variance ranged from 2.27% to 6.44% for intra-observer and 2.39% to 8.42% for inter-observer data. Subgroup analysis showed lower observer-variation for reading of toe pressures in patients with diabetes and/or chronic kidney disease than patients not diagnosed with these conditions. Bland-Altman plots showed higher variation in toe pressure readings than ankle pressure readings. This study shows substantial intra- and inter-observer agreement in diagnostic classification and reading of absolute pressures when using laboratory technologists as observers. The study emphasises that observer variation for curve reading is an important factor concerning the overall reproducibility of the method. Our data suggest diabetes and chronic kidney disease have an influence on toe pressure reproducibility. Copyright © 2013 European Society for Vascular Surgery. Published

Determination of variations of the solar radius from solar eclipse observations

NASA Technical Reports Server (NTRS)

Sofia, S.; Dunham, D. W.; Fiala, A. D.

1980-01-01

This paper describes the method to determine the solar radius and its variations from observations made during total solar eclipses. In particular, the procedure to correct the spherical moon predictions for the effects of lunar mountains and valleys on the width and location of the path of totality is addressed in detail. The errors affecting this technique are addressed, a summary of the results of its application to three solar eclipses are presented, and the implications of the results on the constancy of the solar constant are described.

Detection of significant variation in acoustic output of an electromagnetic lithotriptor.

PubMed

Pishchalnikov, Yuri A; McAteer, James A; Vonderhaar, R Jason; Pishchalnikova, Irina V; Williams, James C; Evan, Andrew P

2006-11-01

We describe the observation of significant instability in the output of an electromagnetic lithotriptor. This instability had a form that was not detected by routine assessment, but rather was observed only by collecting many consecutive shock waves in nonstop regimen. A Dornier DoLi-50 lithotriptor used exclusively for basic research was tested and approved by the regional technician. This assessment included hydrophone measures at select power levels with the collection of about 25 shock waves per setting. Subsequent laboratory characterization used a fiberoptic hydrophone and storage oscilloscope for data acquisition. Waveforms were collected nonstop for hundreds of pulses. Output was typically stable for greater than 1,000 shock waves but substantial fluctuations in acoustic pressures were also observed. For example, output at power level 3 (mean peak positive acoustic pressure +/- SD normally 44 +/- 2 MPa) increased dramatically to greater than 50 MPa or decreased significantly to approximately 30 MPa for hundreds of shock waves. The cause of instability was eventually traced to a faulty lithotriptor power supply. Instability in lithotriptor acoustic output can occur and it may not be detected by routine assessment. Collecting waveforms in a nonstop regimen dramatically increases sampling size, improving the detection of instability. Had the instability that we observed occurred during patient treatment, the energy delivered may well have exceeded the planned dose. Since the potential for adverse effects in lithotripsy increases as the dose is increased, it would be valuable to develop ways to better monitor the acoustic output of lithotriptors.

Clinical significance of rare copy number variations in epilepsy: a case-control survey using microarray-based comparative genomic hybridization.

PubMed

Striano, Pasquale; Coppola, Antonietta; Paravidino, Roberta; Malacarne, Michela; Gimelli, Stefania; Robbiano, Angela; Traverso, Monica; Pezzella, Marianna; Belcastro, Vincenzo; Bianchi, Amedeo; Elia, Maurizio; Falace, Antonio; Gazzerro, Elisabetta; Ferlazzo, Edoardo; Freri, Elena; Galasso, Roberta; Gobbi, Giuseppe; Molinatto, Cristina; Cavani, Simona; Zuffardi, Orsetta; Striano, Salvatore; Ferrero, Giovanni Battista; Silengo, Margherita; Cavaliere, Maria Luigia; Benelli, Matteo; Magi, Alberto; Piccione, Maria; Dagna Bricarelli, Franca; Coviello, Domenico A; Fichera, Marco; Minetti, Carlo; Zara, Federico

2012-03-01

To perform an extensive search for genomic rearrangements by microarray-based comparative genomic hybridization in patients with epilepsy. Prospective cohort study. Epilepsy centers in Italy. Two hundred seventy-nine patients with unexplained epilepsy, 265 individuals with nonsyndromic mental retardation but no epilepsy, and 246 healthy control subjects were screened by microarray-based comparative genomic hybridization. Identification of copy number variations (CNVs) and gene enrichment. Rare CNVs occurred in 26 patients (9.3%) and 16 healthy control subjects (6.5%) (P = .26). The CNVs identified in patients were larger (P = .03) and showed higher gene content (P = .02) than those in control subjects. The CNVs larger than 1 megabase (P = .002) and including more than 10 genes (P = .005) occurred more frequently in patients than in control subjects. Nine patients (34.6%) among those harboring rare CNVs showed rearrangements associated with emerging microdeletion or microduplication syndromes. Mental retardation and neuropsychiatric features were associated with rare CNVs (P = .004), whereas epilepsy type was not. The CNV rate in patients with epilepsy and mental retardation or neuropsychiatric features is not different from that observed in patients with mental retardation only. Moreover, significant enrichment of genes involved in ion transport was observed within CNVs identified in patients with epilepsy. Patients with epilepsy show a significantly increased burden of large, rare, gene-rich CNVs, particularly when associated with mental retardation and neuropsychiatric features. The limited overlap between CNVs observed in the epilepsy group and those observed in the group with mental retardation only as well as the involvement of specific (ion channel) genes indicate a specific association between the identified CNVs and epilepsy. Screening for CNVs should be performed for diagnostic purposes preferentially in patients with epilepsy and mental retardation or

Time Variations of Observed H α Line Profiles and Precipitation Depths of Nonthermal Electrons in a Solar Flare

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

Falewicz, Robert; Radziszewski, Krzysztof; Rudawy, Paweł

2017-10-01

We compare time variations of the H α and X-ray emissions observed during the pre-impulsive and impulsive phases of the C1.1-class solar flare on 2013 June 21 with those of plasma parameters and synthesized X-ray emission from a 1D hydrodynamic numerical model of the flare. The numerical model was calculated assuming that the external energy is delivered to the flaring loop by nonthermal electrons (NTEs). The H α spectra and images were obtained using the Multi-channel Subtractive Double Pass spectrograph with a time resolution of 50 ms. The X-ray fluxes and spectra were recorded by RHESSI . Pre-flare geometric andmore » thermodynamic parameters of the model and the delivered energy were estimated using RHESSI data. The time variations of the X-ray light curves in various energy bands and those of the H α intensities and line profiles were well correlated. The timescales of the observed variations agree with the calculated variations of the plasma parameters in the flaring loop footpoints, reflecting the time variations of the vertical extent of the energy deposition layer. Our result shows that the fast time variations of the H α emission of the flaring kernels can be explained by momentary changes of the deposited energy flux and the variations of the penetration depths of the NTEs.« less

[Variation trend and significance of adult tonsil size and tongue position].

PubMed

Bin, X; Zhou, Y

2016-08-05

Objective: The aim of this study is to explore the changing trend and significance of adult tonsil size and tongue position by observing adults in different age groups. Method: Oropharyngeal cavities of 1 060 adults who undergoing health examination and had no history of tonsil surgery were observed. Friedman tongue position (FTP) and tonsil size (TS) were scored according to Friedman's criteria and results were statistic analyzed to evaluate their changing law and significance. Result: Mean FTP scores increased with age significantly（ P <0.01）; FTP score in male was lower than that in female（ P <0.01）. TS score significantly decreased with age（ P <0.05）.The average score of TS had no statistical significance in different gender. Although there was no statistical significance, total score of FTP show an increasing trend with age（ P >0.05）;Total scores of FTP were different between sexes（male 4.12±0.67，female 4.23±0.68， P <0.05）.BMI was not found to be statistically different when FTP scores, TS scores and total scores changed ( P >0.05); but it showed an increasing trend with age（ P <0.01）. Conclusion: Width of pharyngeal cavity in normal adults is always kept in certain stability, while it proves to be narrower in obese people. TS score and FTP score, which appear the opposite trend with age, can be thought as a major factor to keep a stable width of oral pharyngeal cavity. Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.

Satellite observed global variations in ecosystem-scale plant water storage

NASA Astrophysics Data System (ADS)

Tian, F.; Wigneron, J. P.; Brandt, M.; Fensholt, R.

2017-12-01

Plant water storage is a key component in ecohydrological processes and tightly coupled with global carbon and energy budgets. Field measurements of individual trees have revealed diurnal and seasonal variations in plant water storage across different tree species and sizes. However, global estimation of plant water storage is challenged by up-scaling from individual trees to an ecosystem scale. The L-band passive microwaves are sensitive to water stored in the stems, branches and leaves, with dependence on the vegetation structure. Thus, the L-band vegetation optical depth (L-VOD) parameter retrieved from satellite passive microwave observations can be used as a proxy for ecosystem-scale plant water storage. Here, we employ the recently developed SMOS (Soil Moisture and Ocean Salinity) L-VOD dataset to investigate spatial patterns in global plant water storage and its diurnal and seasonal variations. In addition, we compare the spatiotemporal patterns between plant water storage and canopy greenness (i.e., enhanced vegetation indices, EVI) to gain ecohydrological insights among different territorial biomes, including boreal forest and tropical woodland. Generally, seasonal dynamics of plant water storage is much smaller than canopy greenness, yet the temporal coupling of these two traits is totally different between boreal and tropical regions, which could be related to their strategies in plant water regulation.

Global Albedo Variations on Mars from Recent MRO/MARCI and Other Space-Based Observations

NASA Astrophysics Data System (ADS)

Bell, J. F., III; Wellington, D. F.

2017-12-01

Dramatic changes in Mars surface albedo have been quantified by telescopic, orbital, and surface-based observations over the last 40 years. These changes provide important inputs for global and mesoscale climate models, enabling characterization of seasonal and secular variations in the distribution of mobile surface materials (dust, sand) in the planet's current climate regime. Much of the modern record of dust storms and albedo changes comes from synoptic-scale global imaging from the Viking Orbiter, Mars Global Surveyor (MGS), Hubble Space Telescope (HST), and Mars Reconnaissance Orbiter (MRO) missions, as well as local-scale observations from long-lived surface platforms like the Spirit and Opportunity rovers. Here we focus on the substantial time history of global-scale images acquired from the MRO Mars Color Imager (MARCI). MARCI is a wide-angle multispectral imager that acquires daily coverage of most of the surface at up to 1 km/pixel. MARCI has been in orbit since 2006, providing six Mars years of continuous surface and atmospheric observations, and building on the nearly five previous Mars years of global-scale imaging from the MGS Mars Orbiter Camera Wide Angle (MOC/WA) imager, which operated from 1997 to 2006. While many of the most significant MARCI-observed changes in the surface albedo are the result of large dust storms, other regions experience seasonal darkening events that repeat with different degrees of annual regularity. Some of these are associated with local dust storms, while for others, frequent surface changes take place with no associated evidence for dust storms, suggesting action by seasonally-variable winds and/or small-scale storms/dust devils too small to resolve. Discrete areas of dramatic surface changes across widely separated regions of Tharsis and in portions of Solis Lacus and Syrtis Major are among the regions where surface changes have been observed without a direct association to specific detectable dust storm events

Effect of posture on the diurnal variation in clinically significant diabetic macular edema.

PubMed

Polito, Antonio; Polini, Giovanni; Chiodini, Raffaella Gortana; Isola, Miriam; Soldano, Franca; Bandello, Francesco

2007-07-01

To investigate the role of posture and other systemic factors in the diurnal variation of clinically significant diabetic macular edema (CSDME). Ten eyes of 10 diabetic subjects with CSDME underwent four OCT foveal thickness measurements with StratusOCT at 9 AM and 12, 3, and 6 PM consecutively on two different days, with the subject in an upright position on one and in a recumbent position on the other. For the "recumbent-position" measurements, the patients were admitted the night before and remained in bed during the entire day of testing. Clinical laboratory results at baseline included HbA1c, urinary albumin, and serum creatinine. Refraction and Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity were also measured before each OCT measurement was taken. Variations in blood pressure, body temperature, plasma glucose, renin, aldosterone, and cortisol levels were measured and then correlated with macular thickness. Foveal thickening decreased in all cases over the course of the day. The decrease, however, was significantly greater for the upright-position measurements (relative mean +/- SD decrease of 20.6% +/- 6.5% in the upright position and 6.2% +/- 4.6% in the recumbent position). Visual acuity improved by at least 1 ETDRS line in three eyes in the upright position as opposed to only one eye in the recumbent position. There seemed to be no association between any of the systemic factors studied and foveal thickening, with the exception of cortisol. The results support the hypothesis that posture and hydrostatic pressure play a major role in determining time-related shifts in CSDME and suggest that the forces of Starling's law can in part, account for CSDME formation.

Excitation Location and Seasonal Variation of Transoceanic Infragravity Waves Observed at an Absolute Pressure Gauge Array

NASA Astrophysics Data System (ADS)

Tonegawa, T.; Fukao, Y.; Shiobara, H.; Sugioka, H.; Ito, A.; Yamashita, M.

2018-01-01

An array of 10 absolute pressure gauges (APGs) deployed in deep water 50 km east of Aogashima, an island in southern Japan, observed several isolated signals in the infragravity wave (IGW) frequency band (0.002-0.03 Hz) during boreal summer, whereas relatively high IGW energy persisted during boreal winter. The isolated IGW shows dispersion with a delay time of 4-5 days as a function of frequency. Here we estimate the excitation locations of IGWs for the two seasons with estimated incoming direction of IGW, calculation of transoceanic IGW trajectories and propagation times, and spatiotemporal variations of significant wave heights from WAVEWATCH III. In boreal summer, the isolated IGWs are primarily caused by IGW energies excited at the shoreline of South America, based on the following three observations: IGWs observed at the array originated from the east: the easterly ray path from the array reaches South America: and an event-like IGWs were observed at the array when a storm approaches eastward to the shoreline of South America, in which the observed delay time of 4-5 days was also supported by the frequency-dependent calculation of IGW propagation times. In boreal winter, the incessant IGWs consist of transoceanic IGW energies leaked from the shoreline, primarily from North America, and secondly from South America and the western Aleutian Islands.

Modeling of geomagnetic field secular variations observed in the Balkan area for purposes of regional topographic mapping

NASA Astrophysics Data System (ADS)

Metodiev, Metodi; Trifonova, Petya; Buchvarov, Ivan

2014-05-01

The most significant of the Earth's magnetic field elements is the geomagnetic declination, which is widely used in geodesy, cartography and their associated navigational systems. The geomagnetic declination is incorporated in the naval navigation maps and is used in the navigation process. It is also a very important factor for aviation where declination data have major importance for every airport (civil or military). As the geomagnetic field changes with time but maps of the geomagnetic declination are not published annually and are reduced to an epoch in the past, it is necessary to define two additional parameters in the maps, needed to determine the value of the geomagnetic declination for a particular moment in the future: 1) estimated value of the annual declination variation and 2) a table with the average diurnal variation of the declination for a given month and hour. The goal of our research is to analyze the annual mean values of geomagnetic declination on the territory of the Balkan Peninsula for obtaining of a best fitting model of that parameter which can be used for prediction of the declination value for the next 10 years. The same study was performed in 1990 for the purposes of Bulgarian declination map's preparation. As a result, a linear model of the declination annual variation was obtained for the neighboring observatories and repeat stations data, and a map of the obtained values for the Bulgarian territory was drawn. We use the latest version of the GFZ Reference Internal Magnetic Model (GRIMM-3.0) to compare the magnetic field evolution predicted by that model between 2001 and 2010 to the data collected in five independent geomagnetic observatories in the Balkan region (PAG, SUA, PEG, IZN, GCK) over the same time interval. We conclude that the geomagnetic core field secular variation in this area is well described by the global model. The observed small-scale differences might indicate induced lithospheric anomalies but it is still an open

The Spatiotemporal Structure of 20th Century Climate Variations in Observations and Reanalyses. Part 1; Long-term Trend

NASA Technical Reports Server (NTRS)

Chen, Junye; DelGenio, Anthony D.; Carlson, Barbara e.; Bosilovich, Michael G.

2007-01-01

The dominant interannual El Nino-Southern Oscillation phenomenon (ENSO) and the short length of climate observation records make it difficult to study long-term climate variations in the spatiotemporal domain. Based on the fact that the ENS0 signal spreads to remote regions and induces delayed climate variation through atmospheric teleconnections, we develop an ENSO-removal method through which the ENS0 signal can be approximately removed at the grid box level from the spatiotemporal field of a climate parameter. After this signal is removed, long-term climate variations, namely, the global warming trend (GW) and the Pacific pan-decadal variability (PDV), are isolated at middle and low latitudes in the climate parameter fields from observed and reanalyses datasets. Except for known GW characteristics, the warming that occurs in the Pacific basin (approximately 0.4K in the 2oth century) is much weaker than in surrounding regions and the other two ocean basins (approximately 0.8K). The modest warming in the Pacific basin is likely due to its dynamic nature on the interannual and decadal time scales and/or the leakage of upper ocean water through the Indonesian Throughflow. Based on NCEP/NCAR and ERA-40 reanalyses, a comprehensive atmospheric structure associated with GW is given. Significant discrepancies exist between the two datasets, especially in the tightly coupled dynamic and water vapor fields. The dynamic field based on NCEP/NCAR reanalysis, which shows a change in the Walker Circulation, is consistent with the GW change in the surface temperature field. However, intensification in the Hadley Circulation is associated with GW trend in the ERA-40 reanalysis.

Astronaut observations from lunar orbit and their geologic significance.

NASA Technical Reports Server (NTRS)

El-Baz, F.; Worden, A. M.; Brand, V. D.

1972-01-01

To supplement orbital photography and other remotely sensed data, visual observations were made of 15 lunar surface targets during Apollo mission 15. Among the significant results are (1) characterization of the floor material of Tsiolkovsky as no darker than the average (Eratosthenian) mare material, and interpretration of the lineated unit on the crater rim as a rock avalanche; (2) identification of layers on the wall of the crater Picard, which is probably volcanic in origin, (3) explanation of the ray-excluded zone of the crater Proclus as the result of structurally controlled ray shadowing; (4) observation of cinder cones in the Littrow area with dark haloes that probably are composed of pyroclastic deposits; and (5) recognition that the termini of numerous sinuous rilles in Oceanus Procellarum are flooded with younger mare materials that may have covered older terminal deposits.

Bayesian Analysis of Hmi Images and Comparison to Tsi Variations and MWO Image Observables

NASA Astrophysics Data System (ADS)

Parker, D. G.; Ulrich, R. K.; Beck, J.; Tran, T. V.

2015-12-01

We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from June, 2010 to December, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables.The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment.Ulrich, R.K., Parker, D, Bertello, L. and

Inter-observer variation in identifying mammals from their tracks at enclosed track plate stations

Treesearch

William J. Zielinski; Fredrick V. Schlexer

2009-01-01

Enclosed track plate stations are a common method to detect mammalian carnivores. Studies rely on these data to make inferences about geographic range, population status and detectability. Despite their popularity, there has been no effort to document inter-observer variation in identifying the species that leave their tracks. Four previous field crew leaders...

Interannual Variation in Offshore Advection of Amazon-Orinoco Plume Waters: Observations, Forcing Mechanisms, and Impacts

NASA Astrophysics Data System (ADS)

Fournier, S.; Vandemark, D.; Gaultier, L.; Lee, T.; Jonsson, B.; Gierach, M. M.

2017-11-01

This study investigates sea surface salinity (SSS) and sea surface temperature (SST) variations in the tropical Atlantic east of the Lesser Antilles, a region where freshwater advection from the Amazon and Orinoco Rivers, may potentially impact air-sea interaction. Observations are used to document later-summer variability and evaluate offshore riverine transport from 2010 to 2014. During this period, the largest difference in plume-affected areas, defined as the extent covered by SSS lower than 35.5 pss, is found between 2011 and 2014. Plume waters covered 92% of the study region in 2011 and 60% in 2014, with the average SSS in the study region being 2 pss lower in 2011. Lagrangian particle tracking based on satellite-derived ocean currents is used to diagnose the impact of the river plumes on SSS and SST from 2010 to 2014. Northward freshwater flux in summer 2014 was significantly weaker than fluxes in 2010-2013. This difference is not due to interannual discharge variability, but to significant changes in eddy-driven transport and cross-shore winds. In particular, the stronger cross-shore wind in May 2014 restricted offshore freshwater flow and lead to a smaller plume-affected area. Persistent SST gradients are often found near the plume edge, which may have implications for ocean-atmosphere coupling associated with atmospheric convection. SST in the study region was 1°C higher in 2010 compared to other years, and is related to basin-scale ocean-atmosphere processes. Interannual variation in Amazon advective pathways and the associated SSS changes are also influenced by changes in the ITCZ position between 2011 and 2014.

Deriving mass balance and calving variations from reanalysis data and sparse observations, Glaciar San Rafael, northern Patagonia, 1950-2005

NASA Astrophysics Data System (ADS)

Koppes, M.; Conway, H.; Rasmussen, L. A.; Chernos, M.

2011-09-01

Mass balance variations of Glaciar San Rafael, the northernmost tidewater glacier in the Southern Hemisphere, are reconstructed over the period 1950-2005 using NCEP-NCAR reanalysis climate data together with sparse, local historical observations of air temperature, precipitation, accumulation, ablation, thinning, calving, and glacier retreat. The combined observations over the past 50 yr indicate that Glaciar San Rafael has thinned and retreated since 1959, with a total mass loss of ~22 km3 of ice eq. Over that period, except for a short period of cooling from 1998-2003, the climate has become progressively warmer and drier, which has resulted primarily in pervasive thinning of the glacier surface and a decrease in calving rates, with only minor acceleration in retreat of the terminus. A comparison of calving fluxes derived from the mass balance variations and from theoretical calving and sliding laws suggests that calving rates are inversely correlated with retreat rates, and that terminus geometry is more important than balance fluxes to the terminus in driving calving dynamics. For Glaciar San Rafael, regional climate warming has not yet resulted in the significant changes in glacier length seen in other calving glaciers in the region, emphasizing the complex dynamics between climate inputs, topographic constraints and glacier response in calving glacier systems.

Deriving mass balance and calving variations from reanalysis data and sparse observations, Glaciar San Rafael, northern Patagonia, 1950-2005

NASA Astrophysics Data System (ADS)

Koppes, M.; Conway, H.; Rasmussen, L. A.; Chernos, M.

2011-04-01

Mass balance variations of Glaciar San Rafael, the most equatorial tidewater glacier in the North Patagonian Icefield, are reconstructed over the period 1950-2005 using NCEP-NCAR reanalysis climate data together with sparse, local historical observations of air temperature, precipitation, accumulation, ablation, thinning, calving, and glacier retreat. The combined observations over the past 50 yr indicate that Glaciar San Rafael has thinned and retreated since 1959, with a total mass loss of ~22 km3 of ice equivalent. Over that period, except for a short period of cooling from 1998-2003, the climate has become progressively warmer and drier, which has resulted primarily in pervasive thinning of the glacier surface and a decrease in calving rates, with only minor acceleration in retreat of the terminus. A comparison of calving fluxes derived from the mass balance variations and from theoretical calving and sliding laws suggest that calving rates are inversely correlated with retreat rates, and that terminus geometry is more important than changes in balance fluxes to the terminus in driving calving dynamics. For Glaciar San Rafael, regional climate warming has not yet resulted in the significant changes in glacier length seen in other calving glaciers in the region, emphasizing the complex dynamics between climate inputs, topographic constraints and glacier response in calving glacier systems.

Variation of atmospheric CO, δ13C, and δ18O at high northern latitude during 2004-2009: Observations and model simulations

NASA Astrophysics Data System (ADS)

Park, Keyhong; Wang, Zhihui; Emmons, Louisa K.; Mak, John E.

2015-10-01

Atmospheric CO mixing ratios and stable isotope ratios (δ13C and δ18O) were measured at a high northern latitude site (Westman Islands, Iceland) from January 2004 to March 2010 in order to investigate recent multiyear trends of the sources of atmospheric carbon monoxide in the extratropical Northern Hemisphere. During this period, we observed a decrease of about 2% per year in CO mixing ratios with little significant interannual variability. The seasonal cycles for δ13C and δ18O in CO are similar to that in the CO mixing ratio, and there is a pronounced interannual variation in their seasonal extremes occurring in summer and fall, which is driven by changes in the relative contribution of different sources. Some of the sources of CO are anthropogenic in character (e.g., fossil fuel and biofuel combustion and agricultural waste burning), and some are primarily natural (e.g., oxidation atmospheric methane and other hydrocarbons and wildfires), and distinction among the various major sources can, more or less, be distinguished by the stable isotopic composition of CO. We compare our observations with simulations from a 3-D global chemical transport model (MOZART-4, Model for Ozone and Related Chemical Tracers, version 4). Our results indicate the observed trend of anthropogenic CO emissions is mostly responsible for the observed variation in δ13C and δ18O of CO during 2004-2009. Especially, the δ18O enriched sources such as fossil fuel and biofuel sources are controlling the variation. The modeling results indicate decreasing trends in the fossil fuel and biofuel source contributions at Iceland of -0.61 ± 0.26 ppbv/yr and -0.38 ± 0.10 ppbv/yr, respectively, during the observation period.

Sources of Variation in Creep Testing

NASA Technical Reports Server (NTRS)

Loewenthal, William S.; Ellis, David L.

2011-01-01

Creep rupture is an important material characteristic for the design of rocket engines. It was observed during the characterization of GRCop-84 that the complete data set had nearly 4 orders of magnitude of scatter. This scatter likely confounded attempts to determine how creep performance was influenced by manufacturing. It was unclear if this variation was from the testing, the material, or both. Sources of variation were examined by conducting tests on identically processed specimens at the same specified stresses and temperatures. Significant differences existed between the five constant-load creep frames. The specimen temperature was higher than the desired temperature by as much as 43 C. It was also observed that the temperature gradient was up to 44 C. Improved specimen temperature control minimized temperature variations. The data from additional tests demonstrated that the results from all five frames were comparable. The variation decreased to 1/2 order of magnitude from 2 orders of magnitude for the baseline data set. Independent determination of creep rates in a reference load frame closely matched the creep rates determined after the modifications. Testing in helium tended to decrease the sample temperature gradient, but helium was not a significant improvement over vacuum.

Variation of Equatorial F-region Vertical Neutral Wind and Neutral Temperature during Geomagnetic Storms: Brazil FPI Observations

NASA Astrophysics Data System (ADS)

Sheng, C.; De La Garza, J. L.; Deng, Y.; Makela, J. J.; Fisher, D. J.; Meriwether, J. W.; Mesquita, R.

2015-12-01

An accurate description of vertical neutral winds in the thermosphere is essential to understand how the upper atmosphere responds to the geomagnetic storms. However, vertical wind measurements are difficult to obtain and there are still limited data. Recent observation deployments now permit substantial progress on this issue. In this paper, neutral vertical wind data from Brazil FPI observations at around 240 km altitude during 2009 to 2015 are used for the study of the equatorial vertical wind and neutral temperature variation during geomagnetic activity times. First, the observations during several particular storm periods will be analyzed. Secondly, Epoch analysis will be used to bin all the observed events together to investigate the climatological features of vertical wind and temperature during storms. The results will give us an unprecedented view of the nighttime vertical wind and neutral temperature variations at low latitudes, which is critical to specify the dynamics of the upper atmosphere.

Magnetic Ripples Observed by Low-altitude Satellites and their Relation to Micro-barometric and Ground Magnetic Variations

NASA Astrophysics Data System (ADS)

Iyemori, T.; Aoyama, T.; Nakanishi, K.; Odagi, Y.; Sanoo, Y.; Yokoyama, Y.; Yamada, A.

2017-12-01

The `magnetic ripples' are small scale magnetic fluctuations observed in upper ionosphere by low altitude satellites such as CHAMP or Swarm, and they are spatial structure of field-aligned currents along satellite orbit. They are observed almost always in mid- and low-latitudes. From their geographical and seasonal characteristics, they are supposed to be caused by the atmospheric waves which propagates from lower atmosphere to the ionosphere. Although the global distribution and its local time or seasonal variation of the amplitude of magnetic ripples, or the correlation with meteorological phenomena such as typhoons strongly suggest the cumulus convection as the main origin, we need to clarify which mode of atmospheric waves, i.e., acoustic wave or internal gravity wave, mainly contributes to the magnetic ripples and what meteorological condition correspond them. For those purposes, we analyze ground based magnetic and micro-barometric variations. We try to make quantitative estimation of the contribution from both acoustic and internal mode of gravity waves, acoustic resonance, etc. by calculating PSD (power spectral density) of pressure and ground magnetic variations. In this paper, we present their basic characteristics and discuss the relation with magnetic ripples. [Acknowledgments]: The ground observations have been supported by many people including students at our graduate school and by the collaboration with other institutions.

Spatial Variations of Poloidal and Toroidal Mode Field Line Resonances Observed by MMS

NASA Astrophysics Data System (ADS)

Le, G.; Chi, P. J.; Strangeway, R. J.; Russell, C. T.; Slavin, J. A.; Anderson, B. J.; Kepko, L.; Nakamura, R.; Plaschke, F.; Torbert, R. B.

2017-12-01

Field line resonances (FLRs) are magnetosphere's responses to solar wind forcing and internal instabilities generated by solar wind-magnetospheric interactions. They are standing waves along the Earth's magnetic field lines oscillating in either poloidal or toroidal modes. The two types of waves have their unique frequency characteristics. The eigenfrequency of FLRs is determined by the length of the field line and the plasma density, and thus gradually changes with L. For toroidal mode oscillations with magnetic field perturbations in the azimuthal direction, ideal MHD predicts that each field line oscillates independently with its own eigenfrequency. For poloidal mode waves with field lines oscillating radially, their frequency cannot change with L easily as L shells need to oscillate in sync to avoid efficient damping due to phase mixing. Observations, mainly during quiet times, indeed show that poloidal mode waves often exhibit nearly constant frequency across L shells. Our recent observations, on the other hand, reveal a clear L-dependent frequency trend for a long lasting storm-time poloidal wave event, indicating the wave can maintain its power with changing frequencies for an extended period [Le et al., 2017]. The spatial variation of the frequency shows discrete spatial structures. The frequency remains constant within each discrete structure that spans about 1 REalong L, and changes discretely. We present a follow-up study to investigate spatial variations of wave frequencies using the Wigner-Ville distribution. We examine both poloidal and toroidal waves under different geomagnetic conditions using multipoint observations from MMS, and compare their frequency and occurrence characteristics for insights into their generation mechanisms. Reference: Le, G., et al. (2017), Global observations of magnetospheric high-m poloidal waves during the 22 June 2015 magnetic storm, Geophys. Res. Lett., 44, 3456-3464, doi:10.1002/2017GL073048.

Longitudinal dependence of the seasonal variations of the topside ionospheric and plasmaspheric electron content: observations and model results

NASA Astrophysics Data System (ADS)

Zhang, Man-Lian; Liu, Libo; Ning, Baiqi; Wan, Weixing

2016-07-01

Radio signals transmitted from GPS satellite going through the ionization zone above the Earth will be refracted by the ionized components in the ionosphere and the plasmasphere, which would produce additional transfer delay and generate extra errors in satellite navigation and positioning, etc. These errors have strong relation with the total electron content (TEC) along the signal's travelling path. Therefore TEC is one of the most important parameters required by many users for different modern usage purposes. The topside ionospheric and plasmaspheric electron content makes a large contribution to TEC. In the present study, data for the year 2008 of the topside ionospheric and plasmaspheric electron content (PEC) between the height of 800-20200km above the Earth derived from the upward-looking TEC measurements of the precise orbit determination antenna on board the COSMIC low Earth orbit (LEO) satellites to the GPS signals are used to study the longitudinal dependence of the seasonal variations of PEC. A comparison study of the observed PEC with the IZMIRAN_Plas model results is also made. Our study showed that PEC shows different seasonal variations at different longitudinal sectors: for the 240°E-60°E longitudinal sector, PEC shows a strong annual variation with lowest value in the June solstice and highest value in the December solstice months; In contrast, very weak seasonal variations are observed for PEC at 60°E-240°E longitudinal sector; Comparison study showed that this longitudinal dependence feature of the observed PEC's seasonal variation is not well captured by the IZMIRAN_Plas model result. Acknowledgments This research was supported by the National Natural Science Foundation of China (NSFC No. 41274163)

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data: Vegetation Carbon Density in ESMs

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

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. Here we have compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S–10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1–0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

Significant inconsistency of vegetation carbon density in CMIP5 Earth system models against observational data: Vegetation Carbon Density in ESMs

DOE PAGES

Song, Xia; Hoffman, Forrest M.; Iversen, Colleen M.; ...

2017-09-09

Earth system models (ESMs) have been widely used for projecting global vegetation carbon dynamics, yet how well ESMs performed for simulating vegetation carbon density remains untested. Here we have compiled observational data of vegetation carbon density from literature and existing data sets to evaluate nine ESMs at site, biome, latitude, and global scales. Three variables—root (including fine and coarse roots), total vegetation carbon density, and the root:total vegetation carbon ratios (R/T ratios), were chosen for ESM evaluation. ESM models performed well in simulating the spatial distribution of carbon densities in root (r = 0.71) and total vegetation (r = 0.62).more » However, ESM models had significant biases in simulating absolute carbon densities in root and total vegetation biomass across the majority of land ecosystems, especially in tropical and arctic ecosystems. Particularly, ESMs significantly overestimated carbon density in root (183%) and total vegetation biomass (167%) in climate zones of 10°S–10°N. Substantial discrepancies between modeled and observed R/T ratios were found: the R/T ratios from ESMs were relatively constant, approximately 0.2 across all ecosystems, along latitudinal gradients, and in tropic, temperate, and arctic climatic zones, which was significantly different from the observed large variations in the R/T ratios (0.1–0.8). There were substantial inconsistencies between ESM-derived carbon density in root and total vegetation biomass and the R/T ratio at multiple scales, indicating urgent needs for model improvements on carbon allocation algorithms and more intensive field campaigns targeting carbon density in all key vegetation components.« less

Spatial and Temporal Variations of Surface Characteristics on the Greenland Ice Sheet as Derived from Passive Microwave Observations

NASA Technical Reports Server (NTRS)

Anderson, Mark; Rowe, Clinton; Kuivinen, Karl; Mote, Thomas

1996-01-01

The primary goals of this research were to identify and begin to comprehend the spatial and temporal variations in surface characteristics of the Greenland ice sheet using passive microwave observations, physically-based models of the snowpack and field observations of snowpack and firn properties.

The Spatiotemporal Structure of 20th Century Climate Variations in Observations and Reanalyses. Part 2; Pacific Pan-Decadal Variability

NASA Technical Reports Server (NTRS)

Chen, Junye; DelGenio, Anthony D.; Carlson, Barbara E.; Bosilovich, Michael G.

2007-01-01

The dominant interannual El Nino-Southern Oscillation phenomenon (ENSO) and the short length of climate observation records make it difficult to study long-term climate variations in the spatiotemporal domain. Based on the fact that the ENS0 signal spreads to remote regions and induces delayed climate variation through atmospheric teleconnections, we develop an ENSO-removal method through which the ENS0 signal can be approximately removed at the grid box level from the spatiotemporal field of a climate parameter. After this signal is removed, long-term climate variations, namely, the global warming trend (GW) and the Pacific pan-decadal variability (PDV), are isolated at middle and low latitudes in the climate parameter fields from observed and reanalyses datasets. In this study, we show that one of several PDV interdecadal regime shifts occurred during the 1990s. This significant change in the Pacific basin is comparable but opposite in phase to the 1976 climate regime shift, which results persisting warming in the central-eastern Pacific, and cooling in the North and South Pacific. The 1990s PDV regime shift is consistent with observed changes in ocean biosphere and ocean circulation. A comprehensive picture of PDV as manifested in the troposphere and at the surface is described. In general, the PDV spatial patterns in different parameter fields share some similarities with the patterns associated with ENSO, but important differences exist. First, the PDV atmospheric circulation pattern is shifted westward by about 20deg and its zonal extent is limited to approx.60deg compared to approx.110deg for ENS0 pattern. The westward shift of the PDV wave train produces a different, more west-east oriented, North American teleconnection pattern. The lack of a strong PDV surface temperature (ST) signal in the western equatorial Pacific and the relatively strong ST signal in the subtropical regions are consistent with an atmospheric overturning circulation response that

Study of the footprints of short-term variation in XCO2 observed by TCCON sites using NIES and FLEXPART atmospheric transport models

NASA Astrophysics Data System (ADS)

Belikov, Dmitry A.; Maksyutov, Shamil; Ganshin, Alexander; Zhuravlev, Ruslan; Deutscher, Nicholas M.; Wunch, Debra; Feist, Dietrich G.; Morino, Isamu; Parker, Robert J.; Strong, Kimberly; Yoshida, Yukio; Bril, Andrey; Oshchepkov, Sergey; Boesch, Hartmut; Dubey, Manvendra K.; Griffith, David; Hewson, Will; Kivi, Rigel; Mendonca, Joseph; Notholt, Justus; Schneider, Matthias; Sussmann, Ralf; Velazco, Voltaire A.; Aoki, Shuji

2017-01-01

The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier transform spectrometers (FTSs) that record near-infrared (NIR) spectra of the sun. From these spectra, accurate and precise observations of CO2 column-averaged dry-air mole fractions (denoted XCO2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO2; however, our knowledge of the short-term spatial and temporal variations in XCO2 surrounding the TCCON sites is limited. In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian particle dispersion model (LPDM) to determine the footprints of short-term variations in XCO2 observed by operational, past, future and possible TCCON sites. We propose a footprint-based method for the collocation of satellite and TCCON XCO2 observations and estimate the performance of the method using the NIES model and five GOSAT (Greenhouse Gases Observing Satellite) XCO2 product data sets. Comparison of the proposed approach with a standard geographic method shows a higher number of collocation points and an average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and Reunion Island sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasises that the collocation is sensitive to local meteorological conditions and flux distributions.

Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

NASA Astrophysics Data System (ADS)

De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

2015-11-01

We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and MetOp-B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, and (3) a destriping correction and background normalisation resolved in the across-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 09:30 and 13:30 LT are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15 % when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally, regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features

Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

NASA Astrophysics Data System (ADS)

De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

2015-04-01

We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-Visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, (3) a destriping correction and background normalisation resolved in the along-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 9.30 a.m. and 13.30 p.m. are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15% when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features are

Relativistic electron microbursts and variations in trapped MeV electron fluxes during the 8-9 October 2012 storm: SAMPEX and Van Allen Probes observations

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

Kurita, Satoshi; Miyoshi, Yoshizumi; Blake, J. Bernard

2016-03-06

It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Relativistic electron microbursts have been considered as an important loss mechanism of radiation belt electrons. Here in this paper we report on the observations of relativistic electron microbursts and flux variations of trapped MeV electrons during the 8–9 October 2012 storm, using the SAMPEX and Van Allen Probes satellites. Observations by the satellites show that relativistic electron microbursts correlate well with the rapid enhancement of trapped MeV electron fluxes by chorus wave-particle interactions, indicating that accelerationmore » by chorus is much more efficient than losses by microbursts during the storm. It is also revealed that the strong chorus wave activity without relativistic electron microbursts does not lead to significant flux variations of relativistic electrons. Thus, effective acceleration of relativistic electrons is caused by chorus that can cause relativistic electron microbursts.« less

Diurnal variations of Titan's ionosphere

NASA Astrophysics Data System (ADS)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

2009-06-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

Satellite-derived SIF and CO2 Observations Show Coherent Responses to Interannual Climate Variations

NASA Astrophysics Data System (ADS)

Butterfield, Z.; Hogikyan, A.; Kulawik, S. S.; Keppel-Aleks, G.

2017-12-01

Gross primary production (GPP) is the single largest carbon flux in the Earth system, but its sensitivity to changes in climate is subject to significant uncertainty. Satellite measurements of solar-induced chlorophyll fluorescence (SIF) offer insight into spatial and temporal patterns in GPP at a global scale and, combined with other satellite-derived datasets, provide unprecedented opportunity to explore interactions between atmospheric CO2, GPP, and climate variability. To explore potential drivers of GPP in the Northern Hemisphere (NH), we compare monthly-averaged SIF data from the Global Ozone Monitoring Experiment 2 (GOME-2) with observed anomalies in temperature (T; CRU-TS), liquid water equivalent (LWE) from the Gravity Recovery and Climate Experiment (GRACE), and photosynthetically active radiation (PAR; CERES SYN1deg). Using observations from 2007 through 2015 for several NH regions, we calculate month-specific sensitivities of SIF to variability in T, LWE, and PAR. These sensitivities provide insight into the seasonal progression of how productivity is affected by climate variability and can be used to effectively model the observed SIF signal. In general, we find that high temperatures are beneficial to productivity in the spring, but detrimental in the summer. The influences of PAR and LWE are more heterogeneous between regions; for example, higher LWE in North American temperate forest leads to decreased springtime productivity, while exhibiting a contrasting effect in water-limited regions. Lastly, we assess the influence of variations in terrestrial productivity on atmospheric carbon using a new lower tropospheric CO2 product derived from the Greenhouse Gases Observing Satellite (GOSAT). Together, these data shed light on the drivers of interannual variability in the annual cycle of NH atmospheric CO2, and may provide improved constraints on projections of long-term carbon cycle responses to climate change.

Observed Seasonal Variations of the Upper Ocean Structure and Air-Sea Interactions in the Andaman Sea

NASA Astrophysics Data System (ADS)

Liu, Yanliang; Li, Kuiping; Ning, Chunlin; Yang, Yang; Wang, Haiyuan; Liu, Jianjun; Skhokiattiwong, Somkiat; Yu, Weidong

2018-02-01

The Andaman Sea (AS) is a poorly observed basin, where even the fundamental physical characteristics have not been fully documented. Here the seasonal variations of the upper ocean structure and the air-sea interactions in the central AS were studied using a moored surface buoy. The seasonal double-peak pattern of the sea surface temperature (SST) was identified with the corresponding mixed layer variations. Compared with the buoys in the Bay of Bengal (BOB), the thermal stratification in the central AS was much stronger in the winter to spring, when a shallower isothermal layer and a thinner barrier layer were sustained. The temperature inversion was strongest from June to July because of substantial surface heat loss and subsurface prewarming. The heat budget analysis of the mixed layer showed that the net surface heat fluxes dominated the seasonal SST cycle. Vertical entrainment was significant from April to July. It had a strong cooling effect from April to May and a striking warming effect from June to July. A sensitivity experiment highlighted the importance of salinity. The AS warmer surface water in the winter was associated with weak heat loss caused by weaker longwave radiation and latent heat losses. However, the AS latent heat loss was larger than the BOB in summer due to its lower relative humidity.

Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

NASA Astrophysics Data System (ADS)

Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

2013-12-01

Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

Detecting microsatellites within genomes: significant variation among algorithms.

PubMed

Leclercq, Sébastien; Rivals, Eric; Jarne, Philippe

2007-04-18

Microsatellites are short, tandemly-repeated DNA sequences which are widely distributed among genomes. Their structure, role and evolution can be analyzed based on exhaustive extraction from sequenced genomes. Several dedicated algorithms have been developed for this purpose. Here, we compared the detection efficiency of five of them (TRF, Mreps, Sputnik, STAR, and RepeatMasker). Our analysis was first conducted on the human X chromosome, and microsatellite distributions were characterized by microsatellite number, length, and divergence from a pure motif. The algorithms work with user-defined parameters, and we demonstrate that the parameter values chosen can strongly influence microsatellite distributions. The five algorithms were then compared by fixing parameters settings, and the analysis was extended to three other genomes (Saccharomyces cerevisiae, Neurospora crassa and Drosophila melanogaster) spanning a wide range of size and structure. Significant differences for all characteristics of microsatellites were observed among algorithms, but not among genomes, for both perfect and imperfect microsatellites. Striking differences were detected for short microsatellites (below 20 bp), regardless of motif. Since the algorithm used strongly influences empirical distributions, studies analyzing microsatellite evolution based on a comparison between empirical and theoretical size distributions should therefore be considered with caution. We also discuss why a typological definition of microsatellites limits our capacity to capture their genomic distributions.

Diurnal variations in axial length, choroidal thickness, intraocular pressure, and ocular biometrics.

PubMed

Chakraborty, Ranjay; Read, Scott A; Collins, Michael J

2011-07-11

To investigate the pattern of diurnal variations in axial length (AL), choroidal thickness, intraocular pressure (IOP), and ocular biometrics over 2 consecutive days. Measurements of ocular biometrics and IOP were collected for 30 young adult subjects (15 myopes, 15 emmetropes) at 10 different times over 2 consecutive days. Five sets of measurements were collected each day at approximately 3-hour intervals, with the first measurement taken at ~9 AM and final measurement at ~9 PM. AL underwent significant diurnal variation (P < 0.0001) that was consistently observed across the 2 measurement days. The longest AL was typically observed at the second measurement session (mean time, 12:26) and the shortest AL at the final session of each day (mean time, 21:06). The mean diurnal change in AL was 0.032 ± 0.018 mm. Choroidal thickness underwent significant diurnal variation (mean change, 0.029 ± 0.016 mm; P < 0.001) and varied approximately in antiphase to the AL changes. Significant diurnal variations were also found in vitreous chamber depth (VCD; mean change, 0.06 ± 0.029 mm; P < 0.0001) and IOP (mean change, 3.54 ± 0.84 mm Hg; P < 0.0001). A positive association was found between the variations of AL and IOP (r(2) = 0.17, P < 0.0001) and AL and VCD (r(2) = 0.31, P < 0.0001) and a negative association between AL and choroidal thickness (r(2) = 0.13, P < 0.0001). There were no significant differences in the magnitude and timing of diurnal variations associated with refractive error. Significant diurnal variations in AL, choroidal thickness, and IOP were consistently observed over 2 consecutive days of testing.

Long-time variation in magnetic structure of CeIr 3Si 2: Observation of a nucleation-and-growth process of magnetic domains

DOE PAGES

Motoya, Kiyoichiro; Hagihala, Masato; Takabatake, Toshiro; ...

2016-02-29

CeIr 3Si 2 is the first three-dimensional uniform magnet in which the long-time variation in magnetic structure was observed. To clarify the microscopic mechanism of this magnetic structural change, time-resolved neutron scattering measurements have been reinvestigated. Clear time variations in the line widths as well as the amplitudes of magnetic Bragg diffractions have been observed in this improved instrumentation. On the notion of this observation, a nucleation-and-growth model of magnetic structural change has been presented. The numerical calculation with this model reproduces well the observation.

Long-time variation in magnetic structure of CeIr 3Si 2: Observation of a nucleation-and-growth process of magnetic domains

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

Motoya, Kiyoichiro; Hagihala, Masato; Takabatake, Toshiro

CeIr 3Si 2 is the first three-dimensional uniform magnet in which the long-time variation in magnetic structure was observed. To clarify the microscopic mechanism of this magnetic structural change, time-resolved neutron scattering measurements have been reinvestigated. Clear time variations in the line widths as well as the amplitudes of magnetic Bragg diffractions have been observed in this improved instrumentation. On the notion of this observation, a nucleation-and-growth model of magnetic structural change has been presented. The numerical calculation with this model reproduces well the observation.

IUE observations of longitudinal and temporal variations in the Jovian auroral emission

NASA Technical Reports Server (NTRS)

Skinner, T. E.; Durrance, S. T.; Feldman, P. D.; Moos, H. W.

1984-01-01

The IUE's short wavelength spectrograph has been used to monitor the auroral emissions from Jupiter's northern hemisphere, yielding eight observations between January 1981 and January 1982 of H I Lyman-alpha and the H2 Lyman and Werner bands. Attention is given to an apparent periodic emission flux fluctuation, through detailed modeling of the emission geometry. Two possible auroral zones are defined at the north pole by mapping the magnetic field lines from the Io torus and the magnetotail onto the planet's atmosphere. The observed variation in flux with central meridian longitude is not consistent with a uniform brightness as a function of magnetic longitude in either auroral zone. The data can be fitted by confining the emissions to the region of the northern torus auroral zone, in qualitative agreement with the magnetic anomaly model. A similar emission from the magnetotail auroral zone cannot be ruled out.

Interpretation of biological and mechanical variations between the Lowry versus Bradford method for protein quantification.

PubMed

Lu, Tzong-Shi; Yiao, Szu-Yu; Lim, Kenneth; Jensen, Roderick V; Hsiao, Li-Li

2010-07-01

The identification of differences in protein expression resulting from methodical variations is an essential component to the interpretation of true, biologically significant results. We used the Lowry and Bradford methods- two most commonly used methods for protein quantification, to assess whether differential protein expressions are a result of true biological or methodical variations. MATERIAL #ENTITYSTARTX00026; Differential protein expression patterns was assessed by western blot following protein quantification by the Lowry and Bradford methods. We have observed significant variations in protein concentrations following assessment with the Lowry versus Bradford methods, using identical samples. Greater variations in protein concentration readings were observed over time and in samples with higher concentrations, with the Bradford method. Identical samples quantified using both methods yielded significantly different expression patterns on Western blot. We show for the first time that methodical variations observed in these protein assay techniques, can potentially translate into differential protein expression patterns, that can be falsely taken to be biologically significant. Our study therefore highlights the pivotal need to carefully consider methodical approaches to protein quantification in techniques that report quantitative differences.

Diurnal variation of O3, ClO, HOCl, HO2, and BrO observed by JEM/SMILES

NASA Astrophysics Data System (ADS)

Suzuki, Makoto; Mitsuda, Chihiro; Manago, Naohiro; Imai, Koji; Sakazaki, Takatoshi; Ozeki, Hiroyuki; Nishimoto, Eriko; Naito, Yoko; Akiyoshi, Hidehary; Kinnison, Douglas; Sano, Takuki; Shiotani, Masato

2013-04-01

SMILES; Superconducting Submillimeter-Wave Limb Emission Sounder is a 4 K cooled 625-650 GHz limb sounder to observe O3, HCl, ClO, HO2, HOCl, BrO, HNO3, and O3 isotopes. SMILES had been operated on the International Space Station from Oct. 12, 2009 to Apr. 21, 2010. Since ISS is 51° inclined orbit, 30-45 days SMILES zonal mean could provide diurnal variation of chemical species in the stratosphere and mesosphere. Diurnal variation of O3, ClO, HOCl, HO2, and BrO are compared with two nudged CGCM calculations (SD-WACCM; Specified-dynamics WACCM, and MIROC) and satellite observations. Diurnal variation of O3 agreed with SD-WACCM over 50-82 km, but small peak in the morning (7 am local time) is apparent for the SMILES but not for the SD-WACCM at 70 km. Diurnal variation of ClO agreed quite well between SMILES L2 ver. 2.2 and SD-WACCM from 19 to 76 km altitude region. But nighttime ClO value of SMILES L2 ver. 2,2 above 50 km is less than SD-WACCM (70%), which is not clearly explained by the SMILES retrieval issue or our current knowledge of chemical kinetics. Diurnal variation of HOCl also agreed quite nicely from 31 to 76 km. SMILES HOCl retrieval is difficult since it is strongly affected by nearby O3 isotope and O3 hot band lines, as well as very strong HCl line. The nighttime build up of HOCl observed SMILES at 44-68 km are nicely reproduced by the SD-WACCM calculation using JPL2006 chemical kinetics dataset. But chemical kinetics calculation using SMILES ClO, HO2, and HOCl at 35-45 km altitude supported much faster reaction rate of ClO + HO2 given by JPL2010. HO2 diurnal variation also agreed with SD-WACCM from 24 to 72 km. Above 76 km, SMILES L2 ver. 2.2 needs modification of a priori and its co-variance, and we will get better agreement with model calculations. SMILES L2 ver. 2.2 also shows night time bias due to AOS (Acousto-Optics Spectrometer) characteristics. SMILES Band C BrO observation is strongly interfered by overlapping O3 isotope lines, and it is

A Variational Inverse Model Study of Amazonian Methane Emissions including Observations from the AMAZONICA campaign

NASA Astrophysics Data System (ADS)

Wilson, C. J.; Gloor, M.; Chipperfield, M.; Miller, J. B.; Gatti, L.

2013-12-01

Methane (CH4) is a greenhouse gas which is emitted from a range of anthropogenic and natural sources, and since the industrial revolution its mean atmospheric concentration has climbed dramatically, reaching values unprecedented in at least the past 650,000 years. CH4 produces a relatively high radiative forcing effect upon the Earth's climate, and its atmospheric lifetime of approximately 10 years makes it a more appealing target for the mitigation of climate change over short timescales than long-lived greenhouse gases such as carbon dioxide. However, the spatial and temporal variation of CH4 emissions are still not well understood, though in recent years a number of top-down and bottom-up studies have attempted to construct improved emission budgets. Some top-down studies may suffer from poor observational coverage in tropical regions, however, especially in the planetary boundary layer, where the atmosphere is highly sensitive to emissions. For example, although satellite observations often take a large volume of measurements in tropical regions, these retrievals are not usually sensitive to concentrations at the planet's surface. Methane emissions from Amazon region, in particular, are often poorly constrained. Since emissions form this region, coming mainly from wetland and biomass burning sources, are thought to be relatively high, additional observations in this region would greatly help to constrain the geographical distribution of the global CH4 emission budget. In order to provide such measurements, the AMAZONICA project began to take regular flask measurements of CH4 and other trace gases from aircraft over four Amazonian sites from the year 2010 onwards. We first present a forward modelling study of these observations of Amazonian methane for the year 2010 using the TOMCAT Chemical Transport Model. The model is used to attribute variations at each site to a source type and region, and also to assess the ability of our current CH4 flux estimates to

Pulse-to-pulse variations in accreting X-ray pulsars

NASA Astrophysics Data System (ADS)

Kretschmar, Peter; Marcu, Diana; Kühnel, Matthias; Klochkov, Dmitry; Pottschmidt, Katja; Staubert, Rüdiger; Wilson-Hodge, Colleen A.; Jenke, Peter A.; Caballero, Isabel; Fürst, Felix

2014-01-01

In most accreting X-ray pulsars, the periodic signal is very clear and easily shows up as soon as data covering sufficient pulse periods (a few ten) are available. The mean pulse profile is often quite typical for a given source and with minor variations repeated and recognisable across observations done years or even decades apart. At the time scale of individual pulses, significant pulse-to-pulse variations are commonly observed. While at low energies some of these variations might be explained by absorption, in the hard X-rays they will reflect changes in the accretion and subsequent emission. The amount of these variations appears to be quite different between sources and contains information about the surrounding material as well ass possibly interactions at the magnetosphere. We investigate such variations for a sample of well-known sources.

Detecting microsatellites within genomes: significant variation among algorithms

PubMed Central

Leclercq, Sébastien; Rivals, Eric; Jarne, Philippe

2007-01-01

Background Microsatellites are short, tandemly-repeated DNA sequences which are widely distributed among genomes. Their structure, role and evolution can be analyzed based on exhaustive extraction from sequenced genomes. Several dedicated algorithms have been developed for this purpose. Here, we compared the detection efficiency of five of them (TRF, Mreps, Sputnik, STAR, and RepeatMasker). Results Our analysis was first conducted on the human X chromosome, and microsatellite distributions were characterized by microsatellite number, length, and divergence from a pure motif. The algorithms work with user-defined parameters, and we demonstrate that the parameter values chosen can strongly influence microsatellite distributions. The five algorithms were then compared by fixing parameters settings, and the analysis was extended to three other genomes (Saccharomyces cerevisiae, Neurospora crassa and Drosophila melanogaster) spanning a wide range of size and structure. Significant differences for all characteristics of microsatellites were observed among algorithms, but not among genomes, for both perfect and imperfect microsatellites. Striking differences were detected for short microsatellites (below 20 bp), regardless of motif. Conclusion Since the algorithm used strongly influences empirical distributions, studies analyzing microsatellite evolution based on a comparison between empirical and theoretical size distributions should therefore be considered with caution. We also discuss why a typological definition of microsatellites limits our capacity to capture their genomic distributions. PMID:17442102

Temporal variation of soil moisture over the Wuding River Basin assessed with an eco-hydrological model, in-situ observations and remote sensing

NASA Astrophysics Data System (ADS)

Liu, S.; Mo, X.; Zhao, W.; Naeimi, V.; Dai, D.; Shu, C.; Mao, L.

2008-12-01

For integrative management of soil and water in the Wuding River basin, Loess plateau, China, where severe soil erosion damages are incurred, the ecohydrological behavior of the region is needed to be explored. In this study we focus on the evolution of soil moisture (SM) in the basin. Since there are only twelve years in-situ SM measurements available at two stations from 1992 to 2004, an eco-hydrological processes-based model (VIP, Vegetation Interface Processes model) is employed to simulate the long-term SM, evapotranspiration (ET), vegetation cover and production variation from 1956 to 2004, for the mechanical analysis of SM change. In-situ SM observations and a remotely sensed SM dataset retrieved by the Vienna University of Technology are used to validate the model. The results show that the model is able to capture seasonal SM variations. The seasonal pattern, multi-year variation, standard deviation and CV (coefficient of the variation) of SM at the daily, monthly and annual scale are well explained by the climatic and ecological factors such as precipitation, temperature, net radiation, evapotranspiration, and Leaf Area Index (LAI, denoted as LAI). The annual and inter-annual variability of SM is the lowest comparing with that for other 11-ecohydrological variables. The trend analysis shows that SM is in decreasing tendency at ∝=0.01 level of significance. Its significance is lower than that of runoff and that of temperature (∝=0.001), whereas higher than that of precipitation (∝=0.1). The products of these long-term SM data aim to help integrative management of soil and water resources.

The significance of large variations in oil properties of the Dai Hung field, Vietnam

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

Behrenbruch, P.; Du, P.Q.

1995-10-01

The Dai Hung Oil field, offshore Vietnam, is comprised of a complex subsurface structure containing stacked reservoir sequences typically found in many other Southeast Asian fields. Combined with areal fault compartmentalization, this situation has led to the observed, large variations in oil properties. Furthermore, the depositional environment in terms of burial history has created a unique overpressure situation which also had an affect, particularly on the crude saturation conditions of individual reservoirs. For commercial and technical reasons, this situation required a detailed analysis, both in terms of variation in crude assay and live oil properties. For whole crude properties: gravity,more » K factor, wax content and pour point-graphs were drawn up using a large data base of worldwide crudes against which the Dai Hung data could be validated. In case of PVT properties (bubble point and formation volume factor) existing industry correlations were examined. It could be concluded that the sweet, medium gravity and moderately waxy Dai Hung crude has whole crude properties which are comparable to other, similar crudes. The general framework of crude properties established is suitable to type other crudes, even if limited information is available. Of the existing PVT correlations tested, it was found that Standing`s correlation for the oil formation volume factor and the Kartoatmodjo-Schmidt correlation for the bubble point fitted the Dai Hung crude data the best. For the lower shrinkage Dai Hung crudes the Malaysian oil formation volume factor correlation by Omar-Todd gave the best data fit.« less

Cassini UVIS Observations of the Io Plasma Torus. 3; Observations of Temporal and Azimuthal Variability

NASA Technical Reports Server (NTRS)

Steffl, A. J.; Delamere, P. A.; Bagenal, F.

2006-01-01

In this third paper in a series presenting observations by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near sinusoidal variations in ion composition as a functions of azimuthal position. The azimuthal variation in composition is such that the mixing ratio of S II us strongly correlated with the mixing ratio of S III and the equatorial electron density and strongly anti-correlated with the mixing ratios of both S IV and O II and the equatorial electron temperature. Surprisingly, the azimuthal variation in ion composition is observed to have a period of 10.07 h -- 1.5% longer than the System III rotation period of Jupiter, yet 1.3% shorter than the System UV period defined by [Brown, M. E., 1995. J. Geophys. Res. 100, 21683-21696]. Although the amplitude of the azimuthal variation of S III and O II remained in the range of 2-5%, the amplitude of the S II and S IV compositional variation ranged between 5 and 25% during the UVIS observations. Furthermore, the amplitude of the azimuthal variations of S II and S IV appears to be modulated by its location in System III longitude, such that when the region of maximum S II mixing ration (minimum S IV mixing ratio) is aligned with a System III longitude of 200 deg +/-, the amplitude is a factor of 4 greater than when the variation is anti-aligned. This behavior can explain numerous, often apparently contradictory, observations of variations in the properties of the Io plasma torus with the System III and System IV coordinate systems.

Benign, Pathogenic and Copy Number Variations of Unknown Clinical Significance in Patients with Congenital Malformations and Developmental Delay.

PubMed

Mihaylova, M; Staneva, R; Toncheva, D; Pancheva, M; Hadjidekova, S

2017-06-30

The high frequency (3.0-5.0%) of congenital anomalies (CA) and intellectual disabilities (IDs), make them a serious problem, responsible for a high percentage (33.0%) of neonatal mortality. The genetic cause remains unclear in 40.0% of cases. Recently, molecular karyotyping has become the most powerful method for detection of pathogenic imbalances in patients with multiple CAs and IDs. This method is with high resolution and gives us the opportunity to investigate and identify candidate genes that could explain the genotype-phenotype correlations. This article describes the results from analysis of 81 patients with congenital malformations (CMs), developmental delay (DD) and ID, in which we utilized the CytoChip ISCA oligo microarray, 4 × 44 k, covering the whole genome with a resolution of 70 kb. In the selected group of patients with CAs, 280 copy number variations (CNVs) have been proven, 41 were pathogenic, 118 benign and 121 of unknown clinical significance (average number of variations 3.5). In six patients with established pathogenic variations, our data revealed eight pathogenic aberrations associated with the corresponding phenotype. The interpretation of the other CNVs was made on the basis of their frequency in the investigated group, the size of the variation, content of genes in the region and the type of the CNVs (deletion or duplication).

Diurnal variations of Titan

NASA Astrophysics Data System (ADS)

Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

2009-04-01

We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates.

PubMed

Mountain, David; Keijzers, Gerben; Chu, Kevin; Joseph, Anthony; Read, Catherine; Blecher, Gabriel; Furyk, Jeremy; Bharat, Chrianna; Velusamy, Karthik; Munro, Andrew; Baker, Kylie; Kinnear, Frances; Mukherjee, Ahses; Watkins, Gina; Buntine, Paul; Livesay, Georgia; Fatovich, Daniel

2016-01-01

Overuse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4-10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America. To describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation. A retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation. Fourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8-15.4%; range 9.3-25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1-58.2%) and SSPE 8.8% (CI: 7.1-10.5%) of positive scans. CTPA usage (0.2-1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions. We found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5-3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions of small PE. This suggests that increased diagnoses seem to be of

RESPECT-ED: Rates of Pulmonary Emboli (PE) and Sub-Segmental PE with Modern Computed Tomographic Pulmonary Angiograms in Emergency Departments: A Multi-Center Observational Study Finds Significant Yield Variation, Uncorrelated with Use or Small PE Rates

PubMed Central

Chu, Kevin; Joseph, Anthony; Read, Catherine; Blecher, Gabriel; Furyk, Jeremy; Bharat, Chrianna; Velusamy, Karthik; Munro, Andrew; Baker, Kylie; Kinnear, Frances; Mukherjee, Ahses; Watkins, Gina; Buntine, Paul; Livesay, Georgia

2016-01-01

Introduction Overuse of CT Pulmonary Angiograms (CTPA) for diagnosing pulmonary embolism (PE), particularly in Emergency Departments (ED), is considered problematic. Marked variations in positive CTPA rates are reported, with American 4–10% yields driving most concerns. Higher resolution CTPA may increase sub-segmental PE (SSPE) diagnoses, which may be up to 40% false positive. Excessive use and false positives could increase harm vs. benefit. These issues have not been systematically examined outside America. Aims To describe current yield variation and CTPA utilisation in Australasian ED, exploring potential factors correlated with variation. Methods A retrospective multi-centre review of consecutive ED-ordered CTPA using standard radiology reports. ED CTPA report data were inputted onto preformatted data-sheets. The primary outcome was site level yield, analysed both intra-site and against a nominated 15.3% yield. Factors potentially associated with yield were assessed for correlation. Results Fourteen radiology departments (15 ED) provided 7077 CTPA data (94% ≥64-slice CT); PE were reported in 1028 (yield 14.6% (95%CI 13.8–15.4%; range 9.3–25.3%; site variation p <0.0001) with four sites significantly below and one above the 15.3% target. Admissions, CTPA usage, PE diagnosis rates and size of PE were uncorrelated with yield. Large PE (≥lobar) were 55% (CI: 52.1–58.2%) and SSPE 8.8% (CI: 7.1–10.5%) of positive scans. CTPA usage (0.2–1.5% adult attendances) was correlated (p<0.006) with PE diagnosis but not SSPE: large PE proportions. Discussion/ Conclusions We found significant intra-site CTPA yield variation within Australasia. Yield was not clearly correlated with CTPA usage or increased small PE rates. Both SSPE and large PE rates were similar to higher yield historical cohorts. CTPA use was considerably below USA 2.5–3% rates. Higher CTPA utilisation was positively correlated with PE diagnoses, but without evidence of increased proportions

Chaotic behaviour of the short-term variations in ozone column observed in Arctic

NASA Astrophysics Data System (ADS)

Petkov, Boyan H.; Vitale, Vito; Mazzola, Mauro; Lanconelli, Christian; Lupi, Angelo

2015-09-01

The diurnal variations observed in the ozone column at Ny-Ålesund, Svalbard during different periods of 2009, 2010 and 2011 have been examined to test the hypothesis that they could be a result of a chaotic process. It was found that each of the attractors, reconstructed by applying the time delay technique and corresponding to any of the three time series can be embedded by 6-dimensional space. Recurrence plots, depicted to characterise the attractor features revealed structures typical for a chaotic system. In addition, the two positive Lyapunov exponents found for the three attractors, the fractal Hausdorff dimension presented by the Kaplan-Yorke estimator and the feasibility to predict the short-term ozone column variations within 10-20 h, knowing the past behaviour make the assumption about their chaotic character more realistic. The similarities of the estimated parameters in all three cases allow us to hypothesise that the three time series under study likely present one-dimensional projections of the same chaotic system taken at different time intervals.

Seasonal and Interannual Variations of Ice Sheet Surface Elevation at the Summit of Greenland: Observed and Modeled

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Jun, Li; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Observed seasonal and interannual variations in the surface elevation over the summit of the Greenland ice sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the seasonal elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and seasonal amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer season, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations. In the model, the surface elevation decreases about 20 cm over the seven years due

Modeling of temporal variation of very low frequency radio waves over long paths as observed from Indian Antarctic stations

NASA Astrophysics Data System (ADS)

Sasmal, Sudipta; Basak, Tamal; Chakraborty, Suman; Palit, Sourav; Chakrabarti, Sandip K.

2017-07-01

Characteristics of very low frequency (VLF) signal depends on solar illumination across the propagation path. For a long path, solar zenith angle varies widely over the path and this has a significant influence on the propagation characteristics. To study the effect, Indian Centre for Space Physics participated in the 27th and 35th Scientific Expedition to Antarctica. VLF signals transmitted from the transmitters, namely, VTX (18.2 kHz), Vijayanarayanam, India, and NWC (19.8 kHz), North West Cape, Australia, were recorded simultaneously at Indian permanent stations Maitri and Bharati having respective geographic coordinates 70.75°S, 11.67°E, and 69.4°S, 76.17°E. A very stable diurnal variation of the signal has been obtained from both the stations. We reproduced the signal variations of VLF signal using solar zenith angle model coupled with long wavelength propagation capability (LWPC) code. We divided the whole path into several segments and computed the solar zenith angle (χ) profile. We assumed a linear relationship between the Wait's exponential model parameters effective reflection height (h'), steepness parameter (β), and solar zenith angle. The h' and β values were later used in the LWPC code to obtain the VLF signal amplitude at a particular time. The same procedure was repeated to obtain the whole day signal. Nature of the whole day signal variation from the theoretical modeling is also found to match with our observation to some extent.

Copy number variation of human AMY1 is a minor contributor to variation in salivary amylase expression and activity.

PubMed

Carpenter, Danielle; Mitchell, Laura M; Armour, John A L

2017-02-20

Salivary amylase in humans is encoded by the copy variable gene AMY1 in the amylase gene cluster on chromosome 1. Although the role of salivary amylase is well established, the consequences of the copy number variation (CNV) at AMY1 on salivary amylase protein production are less well understood. The amylase gene cluster is highly structured with a fundamental difference between odd and even AMY1 copy number haplotypes. In this study, we aimed to explore, in samples from 119 unrelated individuals, not only the effects of AMY1 CNV on salivary amylase protein expression and amylase enzyme activity but also whether there is any evidence for underlying difference between the common haplotypes containing odd numbers of AMY1 and even copy number haplotypes. AMY1 copy number was significantly correlated with the variation observed in salivary amylase production (11.7% of variance, P < 0.0005) and enzyme activity (13.6% of variance, P < 0.0005) but did not explain the majority of observed variation between individuals. AMY1-odd and AMY1-even haplotypes showed a different relationship between copy number and expression levels, but the difference was not statistically significant (P = 0.052). Production of salivary amylase is correlated with AMY1 CNV, but the majority of interindividual variation comes from other sources. Long-range haplotype structure may affect expression, but this was not significant in our data.

Real-world geographic variations in the use of cardiac implantable electronic devices - The PANORAMA 2 observational cohort study.

PubMed

Bastian, Dirk; Ebrahim, Iftikhar O; Chen, Ju-Yi; Chen, Mien-Cheng; Huang, Dejia; Huang, Jin-Long; Kuznetsov, Vadim A; Maus, Bärbel; Naik, Ajay M; Verhees, Koen J P; Fagih, Ahmed R Al

2018-06-13

Currently, several geographies around the world remain underrepresented in medical device trials. The PANORAMA 2 study was designed to assess contemporary region-specific differences in clinical practice patterns of patients with cardiac implantable electronic devices (CIEDs). In this prospective, multicenter, observational, multi-national study, baseline and implant data of 4,706 patients receiving Medtronic CIEDs (either de novo device implants, replacements, or upgrades) were analyzed, consisting of: 54% implantable pulse generators (IPGs), 20.3% implantable cardiac defibrillators (ICDs), 15% cardiac resynchronization therapy defibrillators (CRT-Ds), 5.1% cardiac resynchronization therapy pacemakers (CRT-Ps), from 117 hospitals in 23 countries across 4 geographical regions between 2012 and 2016. For all device types, in all regions, there were less females than males enrolled, and women were less likely to have ischemic cardiomyopathy. Implant procedure duration differed significantly across the geographies for all device types. Subjects from emerging countries, women and older patients were less likely to receive a magnetic resonance imaging (MRI)-compatible device. Defibrillation testing differed significantly between the regions. European patients had the highest rates of atrial fibrillation (AF), and the lowest number of implanted single-chamber IPGs. Evaluation of stroke history suggested that the general embolic risk is more strongly associated with stroke than AF. We provide comprehensive descriptive data on patients receiving Medtronic CIEDs from several geographies, some of which are understudied in randomized controlled trials (RCTs). We found significant variations in patient characteristics. Several medical decisions appear to be affected by socioeconomic factors. Long-term follow-up data will help evaluate if these variations require adjustments to outcome expectations. This article is protected by copyright. All rights reserved. This article is

Molecular modelling studies of kdr mutations in voltage gated sodium channel revealed significant conformational variations contributing to insecticide resistance.

PubMed

Yellapu, Nanda Kumar; Gopal, Jeyakodi; Kasinathan, Gunasekaran; Purushothaman, Jambulingam

2018-06-01

Voltage gated sodium channels (VGSC) of mosquito vectors are the primary targets of dichlorodiphenyltrichloroethane (DDT) and other synthetic pyrethroids used in public health programmes. The knockdown resistant (kdr) mutations in VGSC are associated with the insecticide resistance especially in Anophelines. The present study is aimed to emphasize and demarcate the impact of three kdr-mutations such as L1014S, L1014F and L1014H on insecticide resistance. The membrane model of sodium transport domain of VGSC (STD-VGSC) was constructed using de novo approach based on domain and trans-membrane predictions. The comparative molecular modelling studies of wild type and mutant models of STD-VGSC revealed that L1014F mutant was observed to be near native to the wild type model in all the respects, but, L1014S and L1014H mutations showed drastic variations in the energy levels, root mean square fluctuations (RMSF) that resulted in conformational variations. The predicted binding sites also showed variable cavity volumes and RMSF in L1014S and L1014H mutants. Further, DDT also found be bound in near native manner to wild type in L1014F mutant and with variable orientation and affinities in L1014S and L1014H mutants. The variations and fluctuations observed in mutant structures explained that each mutation has its specific impact on the conformation of VGSC and its binding with DDT. The study provides new insights into the structure-function-correlations of mutant STD-VGSC structures and demonstrates the role and effects of kdr mutations on insecticide resistance in mosquito vectors.

Persistent Longitudinal Variations of Plasma Density and DC Electric Fields in the Low Latitude Ionosphere Observed with Probes on the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Freudenreich, H.; Klenzing, J.; Rowland, D.; Liebrecht, C.; Bromund, K.; Roddy, P.

2010-01-01

Continuous measurements using in situ probes on consecutive orbits of the C/N0FS satellite reveal that the plasma density is persistently organized by longitude, in both day and night conditions and at all locations within the satellite orbit, defined by its perigee and apogee of 401 km and 867 km, respectively, and its inclination of 13 degrees. Typical variations are a factor of 2 or 3 compared to mean values. Furthermore, simultaneous observations of DC electric fields and their associated E x B drifts in the low latitude ionosphere also reveal that their amplitudes are also strongly organized by longitude in a similar fashion. The drift variations with longitude are particularly pronounced in the meridional component perpendicular to the magnetic field although they are also present in the zonal component as well. The longitudes of the peak meridional drift and density values are significantly out of phase with respect to each other. Time constants for the plasma accumulation at higher altitudes with respect to the vertical drift velocity must be taken into account in order to properly interpret the detailed comparisons of the phase relationship of the plasma density and plasma velocity variations. Although for a given period corresponding to that of several days, typically one longitude region dominates the structuring of the plasma density and plasma drift data, there is also evidence for variations organized about multiple longitudes at the same time. Statistical averages will be shown that suggest a tidal "wave 4" structuring is present in both the plasma drift and plasma density data. We interpret the apparent association of the modulation of the E x B drifts with longitude as well as that of the ambient plasma density as a manifestation of tidal forces at work in the low latitude upper atmosphere. The observations demonstrate how the high duty cycle of the C/NOFS observations and its unique orbit expose fundamental processes at work in the low latitude

Hydrological and oceanic excitations to polar motion andlength-of-day variation

NASA Astrophysics Data System (ADS)

Chen, J. L.; Wilson, C. R.; Chao, B. F.; Shum, C. K.; Tapley, B. D.

2000-04-01

Water mass redistributions in the global hydrosphere, including continental water storage change and non-steric sea level change, introduce variations in the hydrological angular momentum (HAM) and the oceanic angular momentum (OAM). Under the conservation of angular momentum, HAM and OAM variations are significant excitation sources of the Earth rotational variations at a wide range of timescales. In this paper, we estimate HAM and OAM variations and their excitations to polar motion and length-of-day variation using soil moisture and snow estimates andnon-steric sea level change determined by TOPEX/Poseidon satellite radar altimeter observations and a simplified steric sea level change model. The results are compared with the variations of polar motion and LOD that are not accounted for by the atmosphere. This study indicates that seasonal continental water storage change provides significant contributions to both polar motion and LOD variation, especially to polar motion X, and the non-steric sea level change is responsible for a major part of the remaining excitations at both seasonal scale and high frequencies, particularly in polar motion Y and LOD. The good correlation between OAM contributions and the remaining excitations shows that large-scale non-tidal mass variation exists in the oceans and can be detected by TOPEX/Poseidon altimeter observations.

Rules of parameter variation in homotype series of birdsong can indicate a 'sollwert' significance.

PubMed

Hultsch, H; Todt, D

1996-11-01

Various bird species produce songs which include homotype pattern series, i.e. segments composed of a number of repeated vocal units. We compared such units and analyzed the variation of their parameters, especially in the time and the frequency domain. In addition, we examined whether and how serial changes of both the range and the trend of variation were related to song constituents following the repetitions. Data evaluation showed that variation of specific serial parameters (e.g., unit pitch or unit duration) occurring in the whistle song-types of nightingales (Luscinia megarhynchos) were converging towards a distinct terminal value. Although song-types differed in this terminal value, it was found to play the role of a key cue ('sollwert'). The continuation of a song depended on a preceding attainment of its specific 'sollwert'. Our results suggest that the study of signal parameters and rules of their variations make a useful tool for the behavioral access to the properties of the control systems mediating serial signal performances.

A procedure for the significance testing of unmodeled errors in GNSS observations

NASA Astrophysics Data System (ADS)

Li, Bofeng; Zhang, Zhetao; Shen, Yunzhong; Yang, Ling

2018-01-01

It is a crucial task to establish a precise mathematical model for global navigation satellite system (GNSS) observations in precise positioning. Due to the spatiotemporal complexity of, and limited knowledge on, systematic errors in GNSS observations, some residual systematic errors would inevitably remain even after corrected with empirical model and parameterization. These residual systematic errors are referred to as unmodeled errors. However, most of the existing studies mainly focus on handling the systematic errors that can be properly modeled and then simply ignore the unmodeled errors that may actually exist. To further improve the accuracy and reliability of GNSS applications, such unmodeled errors must be handled especially when they are significant. Therefore, a very first question is how to statistically validate the significance of unmodeled errors. In this research, we will propose a procedure to examine the significance of these unmodeled errors by the combined use of the hypothesis tests. With this testing procedure, three components of unmodeled errors, i.e., the nonstationary signal, stationary signal and white noise, are identified. The procedure is tested by using simulated data and real BeiDou datasets with varying error sources. The results show that the unmodeled errors can be discriminated by our procedure with approximately 90% confidence. The efficiency of the proposed procedure is further reassured by applying the time-domain Allan variance analysis and frequency-domain fast Fourier transform. In summary, the spatiotemporally correlated unmodeled errors are commonly existent in GNSS observations and mainly governed by the residual atmospheric biases and multipath. Their patterns may also be impacted by the receiver.

The color of sea level: Importance of spatial variations in spectral shape for assessing the significance of trends

NASA Astrophysics Data System (ADS)

Hughes, Chris W.; Williams, Simon D. P.

2010-10-01

We investigate spatial variations in the shape of the spectrum of sea level variability based on a homogeneously sampled 12 year gridded altimeter data set. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a fifth-order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times of what would be calculated assuming "white" noise and that the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes over this period.

High Resolution Directional Variation And Time Variation Of Sporadic Meteors

NASA Astrophysics Data System (ADS)

Campbell-Brown, Margaret

2007-10-01

The directional dependence of the flux and orbits of sporadic meteoroids is of great importance to understanding the origin and nature of this population of small solar system bodies. The Canadian Meteor Orbit Radar (CMOR) has recorded over 5 million meteoroid orbits from 2002 to the present. This dataset, larger than any previously available, makes it possible to study the sporadic meteor distribution at much greater spatial resolution than previously possible. The rates of meteor orbits with radiants occurring in two degree bins over the whole sky have been calculated from five years of data. The rates have been corrected for observing biases, such as initial trail radius and the collecting area for each radiant, and weighted to a constant limiting mass and a constant limiting energy. The variation of the rates with solar longitude is also examined. The directional variation of geocentric speed, semimajor axis, eccentricity, inclination and other orbital parameters has been calculated, as have the collision probabilities of each meteoroid with the Earth, and the average collisional lifetime for the observed meteoroids. The majority of meteoroids in the mass range observed by CMOR originate in the helion and antihelion sporadic sources. In addition to the north and south apex sources and the north toroidal source, the CMOR data shows a ring of radiants approximately 55 degrees from the apex, with a significant depletion of radiants immediately inside the ring. The depletion of radiants appears to be caused by removal of meteoroids through collisions, as the collisional lifetimes of meteoroids inside the ring are significantly shorter than those observed outside the ring. Further study of the sporadic meteoroid distribution may reveal whether the complex is in a steady state, and the approximate number and orbital characteristics of the parent bodies. Thanks to the NASA MSFC MEO Office.

Tactical Defenses Against Systematic Variation in Wind Tunnel Testing

NASA Technical Reports Server (NTRS)

DeLoach, Richard

2002-01-01

This paper examines the role of unexplained systematic variation on the reproducibility of wind tunnel test results. Sample means and variances estimated in the presence of systematic variations are shown to be susceptible to bias errors that are generally non-reproducible functions of those variations. Unless certain precautions are taken to defend against the effects of systematic variation, it is shown that experimental results can be difficult to duplicate and of dubious value for predicting system response with the highest precision or accuracy that could otherwise be achieved. Results are reported from an experiment designed to estimate how frequently systematic variations are in play in a representative wind tunnel experiment. These results suggest that significant systematic variation occurs frequently enough to cast doubts on the common assumption that sample observations can be reliably assumed to be independent. The consequences of ignoring correlation among observations induced by systematic variation are considered in some detail. Experimental tactics are described that defend against systematic variation. The effectiveness of these tactics is illustrated through computational experiments and real wind tunnel experimental results. Some tutorial information describes how to analyze experimental results that have been obtained using such quality assurance tactics.

Promise and Capability of NASA's Earth Observing System to Monitor Human-Induced Climate Variations

NASA Technical Reports Server (NTRS)

King, M. D.

2003-01-01

The Earth Observing System (EOS) is a space-based observing system comprised of a series of satellite sensors by which scientists can monitor the Earth, a Data and Information System (EOSDIS) enabling researchers worldwide to access the satellite data, and an interdisciplinary science research program to interpret the satellite data. The Moderate Resolution Imaging Spectroradiometer (MODIS), developed as part of the Earth Observing System (EOS) and launched on Terra in December 1999 and Aqua in May 2002, is designed to meet the scientific needs for satellite remote sensing of clouds, aerosols, water vapor, and land and ocean surface properties. This sensor and multi-platform observing system is especially well suited to observing detailed interdisciplinary components of the Earth s surface and atmosphere in and around urban environments, including aerosol optical properties, cloud optical and microphysical properties of both liquid water and ice clouds, land surface reflectance, fire occurrence, and many other properties that influence the urban environment and are influenced by them. In this presentation I will summarize the current capabilities of MODIS and other EOS sensors currently in orbit to study human-induced climate variations.

Seasonal variations in urinary risk factors among patients with nephrolithiasis

NASA Technical Reports Server (NTRS)

Hill, K.; Poindexter, J.; Pak, C. Y.

1991-01-01

Twenty-four hour urine specimens from 5,677 stone-forming patients throughout the United States were analyzed for seasonal variations in urinary risk factors for nephrolithiasis. Determinations were performed for urine volume, pH, calcium, oxalate, phosphorus, sodium, magnesium, citrate, sulfate, uric acid, and the relative supersaturation (RS) of calcium oxalate, brushite, monosodium urate, and uric acid. Criteria for significant seasonal variation included a significant difference in monthly means of risk factors, seasonal grouping of the data by the Student-Newman-Keuls multiple range test, consistent year-to-year trends and a physiologically significant range. Minimum urine volume of 1.54 +/- 0.70 SD L/day occurred in October while a maximum urine volume of 1.76 +/- 0.78 SD L/day was observed during February. Minimum urine pH of 5.94 +/- 0.64 SD was observed during July and August while a maximum pH of 6.18 +/- 0.61 SD was observed during February. Daily urinary excretion of sodium was lowest during August, 158 +/- 74 SD mEq/day and highest during February 177 +/- 70 SD mEq/day. The RS of brushite and uric acid were found to display significant pH-dependent seasonal variation with a maximum RS of uric acid 2.26 +/- 1.98 SD in June and a low of 1.48 +/- 1.30 SD in February. Maximum RS of brushite 2.75 +/- 2.58 was observed during February. Minimum RS of brushite 1.93 +/- 1.70 SD was observed in June. Phosphorus excretion displayed seasonal variation about a spring-fall axis with a maximum value 1042 +/- 373 SD mg/day in April and a minimum value of 895 +/- 289 SD mg/day. Urine volume, sodium, and pH were significantly lower during the summer (June, July, August) than in the winter (December, January, February). The RS of uric acid was higher, but that of brushite and monosodium urate was lower in the summer than in the winter. The seasonal changes observed in urine volume, pH, sodium, and the RS of brushite and uric acid are consistent with summertime sweating

Hydrological storage variations in a lake water balance, observed from multi-sensor satellite data and hydrological models.

NASA Astrophysics Data System (ADS)

Singh, Alka; Seitz, Florian; Schwatke, Christian; Guentner, Andreas

2013-04-01

Freshwater lakes and reservoirs account for 74.5% of continental water storage in surface water bodies and only 1.8% resides in rivers. Lakes and reservoirs are a key component of the continental hydrological cycle but in-situ monitoring networks are very limited either because of sparse spatial distribution of gauges or national data policy. Monitoring and predicting extreme events is very challenging in that case. In this study we demonstrate the use of optical remote sensing, satellite altimetry and the GRACE gravity field mission to monitor the lake water storage variations in the Aral Sea. Aral Sea is one of the most unfortunate examples of a large anthropogenic catastrophe. The 4th largest lake of 1960s has been decertified for more than 75% of its area due to the diversion of its primary rivers for irrigation purposes. Our study is focused on the time frame of the GRACE mission; therefore we consider changes from 2002 onwards. Continuous monthly time series of water masks from Landsat satellite data and water level from altimetry missions were derived. Monthly volumetric variations of the lake water storage were computed by intersecting a digital elevation model of the lake with respective water mask and altimetry water level. With this approach we obtained volume from two independent remote sensing methods to reduce the error in the estimated volume through least square adjustment. The resultant variations were then compared with mass variability observed by GRACE. In addition, GARCE estimates of water storage variations were compared with simulation results of the Water Gap Hydrology Model (WGHM). The different observations from all missions agree that the lake reached an absolute minimum in autumn 2009. A marked reversal of the negative trend occured in 2010 but water storage in the lake decreased again afterwards. The results reveal that water storage variations in the Aral Sea are indeed the principal, but not the only contributor to the GRACE signal of

Local, Regional, and Global Albedo Variations on Mars From Recent Space-Based Observations: Implications for Future Human Explorers

NASA Astrophysics Data System (ADS)

Bell, J. F.; Wellington, D. F.

2017-06-01

We describe recent as well as historic albedo variations on Mars as observed by space-based telescopes, orbiters, and surface missions, and speculate that some regions might offer fewer dust-related problems for future human explorers than others.

The Variations of Neutron Component of Lunar Radiation Background from LEND LRO Observations

NASA Technical Reports Server (NTRS)

Litvak, M. L.; Mitrofanov, I. G.; Sanin, A. B.; Bakhtin, B. N.; Bodnarik, J. G.; Bodnarik, W. V.; Chin, G.; Evans, L.G.; Harshman, K.; Livengood, T. A.;

Seasonal variations of Mercury's magnesium dayside exosphere from MESSENGER observations

NASA Astrophysics Data System (ADS)

Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

2017-01-01

The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, ∼17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of ∼6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5 cm-3 to 50 cm-3 and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1 × 105 cm-2 s-1 to 8 × 105 cm-2 s-1.

Hydroclimate variations in central and monsoonal Asia over the past 700 years.

PubMed

Fang, Keyan; Chen, Fahu; Sen, Asok K; Davi, Nicole; Huang, Wei; Li, Jinbao; Seppä, Heikki

2014-01-01

Hydroclimate variations since 1300 in central and monsoonal Asia and their interplay on interannual and interdecadal timescales are investigated using the tree-ring based Palmer Drought Severity Index (PDSI) reconstructions. Both the interannual and interdecadal variations in both regions are closely to the Pacific Decadal Oscillation (PDO). On interannual timescale, the most robust correlations are observed between PDO and hydroclimate in central Asia. Interannual hydroclimate variations in central Asia are more significant during the warm periods with high solar irradiance, which is likely due to the enhanced variability of the eastern tropical Pacific Ocean, the high-frequency component of PDO, during the warm periods. We observe that the periods with significant interdecadal hydroclimate changes in central Asia often correspond to periods without significant interdecadal variability in monsoonal Asia, particularly before the 19th century. The PDO-hydroclimate relationships appear to be bridged by the atmospheric circulation between central North Pacific Ocean and Tibetan Plateau, a key area of PDO. While, in some periods the atmospheric circulation between central North Pacific Ocean and monsoonal Asia may lead to significant interdecadal hydroclimate variations in monsoonal Asia.

Hydroclimate Variations in Central and Monsoonal Asia over the Past 700 Years

PubMed Central

Fang, Keyan; Chen, Fahu; Sen, Asok K.; Davi, Nicole; Huang, Wei; Li, Jinbao; Seppä, Heikki

2014-01-01

Hydroclimate variations since 1300 in central and monsoonal Asia and their interplay on interannual and interdecadal timescales are investigated using the tree-ring based Palmer Drought Severity Index (PDSI) reconstructions. Both the interannual and interdecadal variations in both regions are closely to the Pacific Decadal Oscillation (PDO). On interannual timescale, the most robust correlations are observed between PDO and hydroclimate in central Asia. Interannual hydroclimate variations in central Asia are more significant during the warm periods with high solar irradiance, which is likely due to the enhanced variability of the eastern tropical Pacific Ocean, the high-frequency component of PDO, during the warm periods. We observe that the periods with significant interdecadal hydroclimate changes in central Asia often correspond to periods without significant interdecadal variability in monsoonal Asia, particularly before the 19th century. The PDO-hydroclimate relationships appear to be bridged by the atmospheric circulation between central North Pacific Ocean and Tibetan Plateau, a key area of PDO. While, in some periods the atmospheric circulation between central North Pacific Ocean and monsoonal Asia may lead to significant interdecadal hydroclimate variations in monsoonal Asia. PMID:25119567

Does observer bias contribute to variations in the rate of retinopathy of prematurity between centres?

PubMed

Darlow, Brian A; Elder, Mark J; Horwood, L John; Donoghue, Deborah A; Henderson-Smart, David J

2008-01-01

We aimed to indirectly assess the contribution from observer bias to between centre variability in the incidence of acute retinopathy of prematurity (ROP). The Australian and New Zealand Neonatal Network (ANZNN) collected data on the highest stage of acute ROP in either eye in 2286 infants born at less than 29 weeks in 1998-1999 and cared for in one of 25 neonatal intensive care units (NICUs). Chi-squared analysis was used to detect differences in the proportion of stages of ROP for each neonatal intensive care unit. These proportions were compared with those reported in two large studies of treatment for ROP. The incidence of acute ROP in the ANZNN cohort was 42% and the ratio of stage 1:2:3 ROP was 1.5:1.9:1. There was considerable variation in both the incidence of acute ROP and the proportions with stage 1:2:3 ROP between centres. A chi-squared test determined that the assignment of stages 1, 2 and 3/4 ROP was not independent of centre (chi(2)(48) = 165.2; P < 0.0001). Treatment of stage 3 ROP varied between 15% and 120%, indicating some eyes were treated at less than stage 3. The data are highly suggestive of observer bias contributing to the observed between centre variation in the incidence of acute ROP. In neonatal intervention studies where acute ROP is an outcome it would seem important to have an accreditation process for examining ophthalmologists, and there are similar arguments for neonatal networks which collect these data.

Detecting climate variations and change: New challenges for observing and data management systems

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

Karl, T.R.; Quayle, R.G.; Groisman, P.Ya.

1993-08-01

Several essential aspects of weather observing and the management of weather data related to improving knowledge of climate variations and change in the surface boundary layer and the consequences for socioeconomic and biogeophysical systems, are discussed. The issues include long-term homogeneous time series of routine weather observations; time- and space-scale resolution of datasets derived from the observations; information about observing systems, data collection systems, and data reduction algorithms; and the enhancement of weather observing systems to serve as climate observing systems. Although much has been learned from existing weather networks and methods of data management, the system is far frommore » perfect. Several vital areas have not received adequate attention. Particular improvements are needed in the interaction between network designers and climatologists; operational analyses that focus on detecting and documenting outliers and time-dependent biases within datasets; developing the means to cope with and minimize potential inhomogeneities in weather observing systems; and authoritative documentation of how various aspects of climate have or have not changed. In this last area, close attention must be given to time and space resolution of the data. In many instances the time and space resolution requirements for understanding why the climate changes are not synonymous with understanding how it has changed or varied. This is particularly true within the surface boundary layer. A standard global daily/monthly climate message should also be introduced to supplement current Global Telecommunication System's CLIMAT data. Overall, a call is made for improvements in routine weather observing, data management, and analysis systems. Routine observations have provided (and will continue to provide) most of the information regarding how the climate has changed during the last 100 years affecting where we live, work, and grow our food. 58 refs., 8 figs

Density variations of meteor flux along the Earth's orbit

NASA Technical Reports Server (NTRS)

Svetashkova, N. T.

1987-01-01

No model of distribution of meteor substance is known to explain the observed diurnal and annual variations of meteor rates, if that distribution is assumed to be constant during the year. Differences between the results of observations and the prediction of diurnal variation rates leads to the conclusion that the density of the orbits of meteor bodies changes with the motion of the Earth along its orbit. The distributions of the flux density over the celestial sphere are obtained by the method described previously by Svetashkova, 1984. The results indicate that the known seasonal and latitudinal variations of atmospheric conditions does not appear to significantly affect the value of the mean flux density of meteor bodies and the matter influx onto the Earth.

Impact of Institutional Review Board Practice Variation on Observational Health Services Research

PubMed Central

Green, Lee A; Lowery, Julie C; Kowalski, Christine P; Wyszewianski, Leon

2006-01-01

Objective To describe, qualitatively and quantitatively, the impact of a review by multiple institutional review boards (IRBs) on the conduct of a multisite observational health services research study. Data Source and Setting Primary data collection during 2002, 2003, and 2004 at 43 United States Department of Veterans Affairs (VA) primary care clinics. Design Explanatory sequential mixed methods design incorporating qualitative and quantitative elements in sequence. Data Collection and Abstraction Methods Field notes and documents collected by research staff during a multisite observational health services research study were used in thematic analysis. Themes were quantified descriptively and merged with timeline data. Principal Findings Approximately 4,680 hours of staff time over a 19-month period were devoted solely to the IRB process. Four categories of phenomena impacting research were observed: Recruitment, retention, and communication issues with local site principal investigators (PIs). Local PIs had no real role but were required by IRBs. Twenty-one percent of sites experienced turnover in local PIs, and local PI issues added significant delay to most sites.Wide variation in standards applied to review and approval of IRB applications. The study was designed to be qualified under U.S. government regulations for expedited review. One site exempted it from review (although it did not qualify for exemption), 10 granted expedited review, 31 required full review, and one rejected it as being too risky to be permitted. Twenty-three required inapplicable sections in the consent form and five required HIPAA (Health Insurance Portability and Accountability Act of 1996) consent from physicians although no health information was asked of them. Twelve sites requested, and two insisted upon, provisions that directly increased the risk to participants.Multiple returns for revision of IRB applications, consent documents, and ancillary forms. Seventy-six percent of

Space-Time Variations in Water Vapor as Observed by the UARS Microwave Limb Sounder

NASA Technical Reports Server (NTRS)

Elson, Lee S.; Read, William G.; Waters, Joe W.; Mote, Philip W.; Kinnersley, Jonathan S.; Harwood, Robert S.

1996-01-01

Water vapor in the upper troposphere has a significant impact on the climate system. Difficulties in making accurate global measurements have led to uncertainty in understanding water vapor's coupling to the hydrologic cycle in the lower troposphere and its role in radiative energy balance. The Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite is able to retrieve water vapor concentration in the upper troposphere with good sensitivity and nearly global coverage. An analysis of these preliminary retrievals based on 3 years of observations shows the water vapor distribution to be similar to that measured by other techniques and to model results. The primary MLS water vapor measurements were made in the stratosphere, where this species acts as a conserved tracer under certain conditions. As is the case for the upper troposphere, most of the stratospheric discussion focuses on the time evolution of the zonal mean and zonally varying water vapor. Stratospheric results span a 19-month period and tropospheric results a 36-month period, both beginning in October of 1991. Comparisons with stratospheric model calculations show general agreement, with some differences in the amplitude and phase of long-term variations. At certain times and places, the evolution of water vapor distributions in the lower stratosphere suggests the presence of meridional transport.

Measuring FeO variation using astronomical spectroscopic observations

NASA Astrophysics Data System (ADS)

Unterguggenberger, Stefanie; Noll, Stefan; Feng, Wuhu; Plane, John M. C.; Kausch, Wolfgang; Kimeswenger, Stefan; Jones, Amy; Moehler, Sabine

2017-03-01

Airglow emission lines of OH, O2, O and Na are commonly used to probe the MLT (mesosphere-lower thermosphere) region of the atmosphere. Furthermore, molecules like electronically excited NO, NiO and FeO emit a (pseudo-) continuum. These continua are harder to investigate than atomic emission lines. So far, limb-sounding from space and a small number of ground-based low-to-medium resolution spectra have been used to measure FeO emission in the MLT. In this study the medium-to-high resolution echelle spectrograph X-shooter at the Very Large Telescope (VLT) in the Chilean Atacama Desert (24°37' S, 70°24' W; 2635 m) is used to study the FeO pseudo-continuum in the range from 0.5 to 0.72 µm based on 3662 spectra. Variations of the FeO spectrum itself, as well as the diurnal and seasonal behaviour of the FeO and Na emission intensities, are reported. These airglow emissions are linked by their common origin, meteoric ablation, and they share O3 as a common reactant. Major differences are found in the main emission peak of the FeO airglow spectrum between 0.58 and 0.61 µm, compared with a theoretical spectrum. The FeO and Na airglow intensities exhibit a similar nocturnal variation and a semi-annual seasonal variation with equinoctial maxima. This is satisfactorily reproduced by a whole atmosphere chemistry climate model, if the quantum yields for the reactions of Fe and Na with O3 are 13 ± 3 and 11 ± 2 % respectively. However, a comparison between the modelled O3 in the upper mesosphere and measurements of O3 made with the SABER satellite instrument suggests that these quantum yields may be a factor of ˜ 2 smaller.

Estimation of plasma lipids and its significance on histopathological grades in oral cancer: Prognostic significance an original research.

PubMed

Sherubin, Eugenia J; Kannan, Karthiga S; Kumar, Dhineksh N; Joseph, Isaac

2013-01-01

Alterations in the lipid profile have long been associated with various cancers because lipids play a key role in maintenance of cell integrity. This study was to estimate the plasma lipid levels in patients with oral cancer and to correlate the values with the histopathological grades. The study group included 50 patients with oral cancer aged between 20 and 60 years who had visited the Department of Oral Medicine and Radiology during the period of September 2005 to July 2007. After the histotopathological confirmation, their plasma lipid levels were estimated using auto analyzer and the data was statistically analyzed. The study revealed a significant decrease in the total plasma lipid levels in patients with oral cancer in comparison with the standard values. Comparing the plasma lipid levels with the histopathological grades, we observed a significant variation in the levels of total cholesterol, very low density lipoprotein, low-density lipoprotein, high-density lipoprotein and triglycerides. The variation in the levels of plasma cholesterol and other lipid constituents in patients with cancer might be due to their increased utilization by neoplastic cells for new membrane biosynthesis. This study was an attempt to estimate the plasma lipids in oral cancer patients and its significance on histopathological grades. We observed a relationship between lower plasma lipids and oral cancer. The result of our study strongly warrants an in-depth research with larger samples and a longer follow-up to consider the low plasma lipid status in oral cancer patients as a useful indicator to assess the course and prognosis of the disease.

Observed temporal variations in the Earth's gravity field from 16-year Starlette orbit analysis

NASA Technical Reports Server (NTRS)

Cheng, M. K.; Eanes, R. L.; Shum, C. K.; Schutz, B. E.; Tapley, B. D.

1992-01-01

Satellite laser ranging data to Starlette, collected during the period from 1975 to 1990, are analyzed to determine yearly values of the second degree annual (Sa) and semiannual (Ssa) tides, simultaneously with average values of other low degree and order tide parameters. The yearly fluctuations in the values for Sa and Ssa are associated with changes in the Earth's second degree zonal harmonic caused by meteorological excitation. The Starlette-determined mean values for the amplitude of the annual and semiannual variations in J2 are 32.3 x 10 exp -11 and 19.5 x 10 exp -11, respectively; while the rms about the mean values are 4.1 x 10 exp -11 and 6.3 x 10 exp -11, respectively. The annual delta-J2 is in good agreement with the value obtained from the combined effects of air mass redistribution without the oceanic inverted-barometer effects (non-IB) and hydrological change. Approximately 90 percent of the observed annual variation from Starlette is attributed to the meteorological mass redistribution occurring on the Earth's surface.

Fetal heart rate monitoring of short term variation (STV): a methodological observational study.

PubMed

Wretler, Stina; Holzmann, Malin; Graner, Sophie; Lindqvist, Pelle; Falck, Susanne; Nordström, Lennart

2016-03-16

Cardiotocography (CTG) has high sensitivity, but less specificity in detection of fetal hypoxia. There is need for adjunctive methods easy to apply during labor. Low fetal heart rate short term variation (STV) is predictive for hypoxia during the antenatal period. The objectives of our study were to methodologically evaluate monitoring of STV during labor and to compare two different monitors (Sonicaid™ and EDAN™) for antenatal use. A prospective observational study at the obstetric department, Karolinska University hospital, Stockholm (between September 2011 and April 2015). In 100 women of ≥ 36 weeks gestation, STV values were calculated during active labor. In a subset of 20 women we compared STV values between internal and external signal acquisition. Additionally we compared antenatal monitoring with two different monitors in another 20 women. Median STV in 100 fetuses monitored with scalp electrode during labor (EDAN™) was 7.1 msec (range 1.3-25.9) with no difference between early (3-6 cm) and late (7-10 cm) labor (7.1 vs 6.8 msec; p = 0.80). STV calculated from scalp electrode signals were positively correlated with delta-STV (STV internal -external) (R = 0.70; p < 0.01). No significant differences were found between Sonicaid™ and EDAN™ in antenatal external monitoring of STV (median difference 0.9 msec, Spearman Rank Correlation Sonicaid vs delta-STV; R = 0.35; p = 0.14). Median intrapartum STV was 7.1 msec. Significant differences were found between internal and external signal acquisition, a finding that suggests further intrapartum studies to be analysed separately depending upon type of signal acquisition. Antenatal external monitoring with Sonicaid™ and EDAN™ indicates that the devices perform equally well in the identification of acidemic fetuses. Further studies are needed to assess the clinical value of intrapartum STV.

Comparison of Magnetospheric Magnetic Field Variations at Quasi-Zenith Orbit Based on Michibiki Observation and REPPU Global MHD Simulation

NASA Astrophysics Data System (ADS)

Kubota, Y.; Nagatsuma, T.; Den, M.; Nakamizo, A.; Matsumoto, H.; Tanaka, T.

2017-12-01

We are developing a numerical simulator for future space weather forecast using magnetosphere-ionosphere coupling global MHD simulation called REPPU (REProduce Plasma Universe) code. We investigate the validity of the MHD simulation result as compared with observation. In this study we simulate some events including both quiet and disturbed geomagnetic conditions using OMNIWeb solar wind data. The simulation results are compared with magnetic field observations from Michibiki satellite, which is on the quasi-zenith orbit (QZO). In quiet geomagnetic condition, magnetic field variations at QZO obtained from simulation results have good consistency as compared correspondence with those from Michibiki observation. In disturbed geomagnetic condition in which the Dst < -20 nT, however, V component of magnetic field variations from simulation results tend to deviate from observations especially at the night side. We consider that this deviation during disturbed geomagnetic condition might be due to tail and/or ring current enhancement which is already suggested by many other MHD simulation studies as compared with the magnetic field observation at geosynchronous orbit. In this presentation, we will discuss the cause of this discrepancy in more detail with studying the relationship between the magnetic field deviation and some parameters such as Dst and solar wind.

Seasonal Ozone Variations in the Isentropic Layer between 330 and 380 K as Observed by SAGE 2: Implications of Extratropical Cross-Tropopause Transport

NASA Technical Reports Server (NTRS)

Wang, Pi-Huan; Cunnold, Derek M.; Zawodny, Joseph M.; Pierce, R. Bradley; Olson, Jennifer R.; Kent, Geoffrey S.; Skeens, Kristi, M.

1998-01-01

To provide observational evidence on the extratropical cross-tropopause transport between the stratosphere and the troposphere via quasi-isentropic processes in the middleworld (the part of the atmosphere in which the isentropic surfaces intersect the tropopause), this report presents an analysis of the seasonal variations of the ozone latitudinal distribution in the isentropic layer between 330 K and 380 K based on the measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The results from SAGE II data analysis are consistent with (1) the buildup of ozone-rich air in the extratropical middleworld through the large-scale descending mass circulation during winter, (2) the spread of ozone-rich air in the isentropic layer from midlatitudes to subtropics via quasi-isentropic transport during spring, (3) significant photochemical ozone removal and the absence of an ozone-rich supply of air to the layer during summer, and (4) air mass exchange between the subtropics and the extratropics during the summer monsoon period. Thus the SAGE II observed ozone seasonal variations in the middleworld are consistent with the existing model calculated annual cycle of the diabatic circulation as well as the conceptual role of the eddy quasi-adiabatic transport in the stratosphere-troposphere exchange reported in the literature.

Spatial Variations of Spectral Properties of (21) Lutetia as Observed by OSIRIS/Rosetta

NASA Astrophysics Data System (ADS)

Leyrat, Cedric; Sierks, H.; Barbieri, C.; Barucci, A.; Da Deppo, V.; De Leon, J.; Fulchignoni, M.; Fornasier, S.; Groussin, O.; Hviid, S. F.; Jorda, L.; Keller, H. U.; La Forgia, F.; Lara, L.; Lazzarin, M.; Magrin, S.; Marchi, S.; Thomas, N.; Schroder, S. E.; OSIRIS Team

2010-10-01

On July 10, 2010, the Rosetta ESA/NASA spacecraft successfully flew by the asteroid (21) Lutetia, which becomes the largest asteroid observed by a space probe. The closest approach occurred at 15H45 UTC at a relative speed of 15km/s and a relative distance of 3160 km. The Narrow Angle Camera (NAC) and the Wide Angle Camera (WAC) of the OSIRIS instrument onboard Rosetta acquired images at different phase angles ranging from almost zero to more than 150 degrees. The best spatial resolution (60 m/pixel) allowed to reveal a very complex topography with several features and different crater's surface densities. Spectrophotometric analysis of the data could suggest spatial variations of the albedo and spectral properties at the surface of the asteroid, at least in the northern hemisphere. Numerous sets of data have been obtained at different wavelengths from 270nm to 980nm. We will first present a color-color analysis of data in order to locate landscapes where surface variegation is present. We will also present a more accurate study of spectral properties using the shape model and different statistical methods. Possible variations of the surface spectral properties with the slope of the ground and the gravity field orientation will be discussed as well.

Lidar observed seasonal variation of vertical canopy structure in the Amazon evergreen forests

NASA Astrophysics Data System (ADS)

Tang, H.; Dubayah, R.

2017-12-01

Both light and water are important environmental factors governing tree growth. Responses of tropical forests to their changes are complicated and can vary substantially across different spatial and temporal scales. Of particular interest is the dry-season greening-up of Amazon forests, a phenomenon undergoing considerable debates whether it is real or a "light illusion" caused by artifacts of passive optical remote sensing techniques. Here we analyze seasonal dynamic patterns of vertical canopy structure in the Amazon forests using lidar observations from NASA's Ice, Cloud, and and land Elevation Satellite (ICESat). We found that the net greening of canopy layer coincides with the wet-to-dry transition period, and its net browning occurs mostly at the late dry season. The understory also shows a seasonal cycle, but with an opposite variation to canopy and minimal correlation to seasonal variations in rainfall or radiation. Our results further suggest a potential interaction between canopy layers in the light regime that can optimize the growth of Amazon forests during the dry season. This light regime variability that exists in both spatial and temporal domains can better reveal the dry-season greening-up phenomenon, which appears less obvious when treating the Amazon forests as a whole.

Observations of Fe XIV Line Intensity Variations in the Solar Corona During the 21 August 2017 Solar Eclipse

NASA Astrophysics Data System (ADS)

Johnson, Payton; Ladd, Edwin

2018-01-01

We present time- and spatially-resolved observations of the inner solar corona in the 5303 Å line of Fe XIV, taken during the 21 August 2017 solar eclipse from a field observing site in Crossville, TN. These observations are used to characterize the intensity variations in this coronal emission line, and to compare with oscillation predictions from models for heating the corona by magnetic wave dissipation.The observations were taken with two Explore Scientific ED 102CF 102 mm aperture triplet apochromatic refractors. One system used a DayStar custom-built 5 Å FWHM filter centered on the Fe XIV coronal spectral line and an Atik Titan camera for image collection. The setup produced images with a pixel size of 2.15 arcseconds (~1.5 Mm at the distance to the Sun), and a field of view of 1420 x 1060 arcseconds, covering approximately 20% of the entire solar limb centered near the emerging sunspot complex AR 2672. We obtained images with an exposure time of 0.22 seconds and a frame rate of 2.36 Hz, for a total of 361 images during totality.An identical, co-aligned telescope/camera system observed the same portion of the solar corona, but with a 100 Å FWHM Baader Planetarium solar continuum filter centered on a wavelength of 5400 Å. Images with an exposure time of 0.01 seconds were obtained with a frame rate of 4.05 Hz. These simultaneous observations are used as a control to monitor brightness variations not related to coronal line oscillations.

Intrapopulation Genome Size Variation in D. melanogaster Reflects Life History Variation and Plasticity

PubMed Central

Ellis, Lisa L.; Huang, Wen; Quinn, Andrew M.; Ahuja, Astha; Alfrejd, Ben; Gomez, Francisco E.; Hjelmen, Carl E.; Moore, Kristi L.; Mackay, Trudy F. C.; Johnston, J. Spencer; Tarone, Aaron M.

2014-01-01

We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions. PMID:25057905

Spectral Structure of Temperature Variations in the Midlatitude Mesopause Region

NASA Astrophysics Data System (ADS)

Perminov, V. I.; Semenov, A. I.; Medvedeva, I. V.; Pertsev, N. N.; Sukhodoev, V. A.

2018-01-01

Long-term series of midnight temperature in the mesopause region have been obtained from spectral observations of hydroxyl airglow emission (OH(6-2) λ840 nm band) at the Tory station (52° N, 103° E) in 2008-2016 and Zvenigorod (56° N, 37° E) station in 2000-2016. On their basis, the Lomb-Scargle spectra of the variations in the period range from 12 days to 11 years have been determined. Estimates of the amplitudes of statistically significant temperature fluctuations are made. The dominant oscillations are the first and second harmonics of the annual variation, the amplitudes of which are 23-24 K and 4-7 K, respectively. The remaining variations, the number of which was 16 for the Tory and 22 for Zvenigorod stations, have small amplitudes (0.5-3 K). Oscillations with combinational frequencies, which arise from modulation of the annual variation harmonics, are observed in a structure of the variation spectra in addition to interannual oscillations (periods from 2 to 11 years) and harmonics of the annual variation (up to its tenth harmonic).

Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

NASA Technical Reports Server (NTRS)

Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

2017-01-01

The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

An investigation of surface albedo variations during the recent sahel drought. [ats 3 observations

NASA Technical Reports Server (NTRS)

Norton, C. C.; Mosher, F. R.; Hinton, B.

1978-01-01

Applications Technology Satellite 3 green sensor data were used to measure surface reflectance variations in the Sahara/Sahel during the recent drought period; 1967 to 1974. The magnitude of the seasonal reflectance change is shown to be as much as 80% for years of normal precipitation and less than 50% for drought years. Year to year comparisons during both wet and dry seasons reveal the existence of a surface reflectance cycle coincident with the drought intensity. The relationship between the green reflectance and solar albedo is examined and estimated to be about 0.6 times the reflectance change observed by the green channel.

Energy spectra variations of high energy electrons in magnetic storms observed by ARASE and HIMAWARI

NASA Astrophysics Data System (ADS)

Takashima, T.; Higashio, N.; Mitani, T.; Nagatsuma, T.; Yoshizumi, M.

2017-12-01

The ARASE spacecraft was launched in December 20, 2016 to investigate mechanisms for acceleration and loss of relativistic electrons in the radiation belts during space storms. The six particle instruments with wide energy range (a few eV to 10MeV) are onboard the ARASE spacecraft. Especially, two particle instruments, HEP and XEP observe high energy electron with energy range from 70keV to over 10Mev. Those instruments observed several geomagnetic storms caused by coronal hole high speed streams or coronal mass ejections from March in 2017. The relativistic electrons in the outer radiation belt were disappeared/increased and their energy spectra were changed dynamically in some storms observed by XEP/HEP onboard the ARASE spacecraft. In the same time, SEDA-e with energy range 200keV-4.5MeV for electron on board the HIMAWARI-8, Japanese weather satellite on GEO, observed increase of relativistic electron in different local time. We will report on energy spectra variations of high energy electrons including calibrations of differential flux between XEP and HEP and discuss comparisons with energy spectra between ARAE and HIMAWARI that observed each storm in different local time.

Observation of daily and annular variations in the 214Po half-life

NASA Astrophysics Data System (ADS)

Alexeev, E. N.; Gavrilyuk, Yu. M.; Gangapshev, A. M.; Gezhaev, A. M.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Ratkevich, S. S.

2017-11-01

Results of the analysis of a time series of values of the half-life (τ) of the 214Po nucleus with a different time step obtained from the TAU-1 (354 days) and TAU-2 (973 days) installations are presented. The annual variation with an amplitude of (9.8 ± 0.6) × 10-4 and daily variations in the solar, lunar, and sidereal times with amplitudes of (5.3 ± 0.3) × 10-4, (6.9 ± 2.0) × 10-4, and (7.2 ± 1.2) × 10-4, respectively, are found in the series of τ values. It is shown that variations in microclimatic parameters cannot be a cause of τ variations.

Detection and interpretation of ocean roughness variations across the Gulf Stream inferred from radar cross section observations

NASA Technical Reports Server (NTRS)

Weissman, D. E.; Thompson, T. W.

1977-01-01

Radar cross section data shows that the Gulf Stream has a higher cross section per unit area (interpreted here as a greater roughness) than the water on the continental shelf. A steep gradient in cross section was often seen at the expected location of the western boundary. There were also longer-scale (10-20 km) gradual fluctuations within the stream of significant magnitude. These roughness variations are correlated with the surface shear stress that the local wind imposes on the sea. Using the available surface-truth information concerning the wind speed and direction, an assumed Gulf Stream velocity profile, and high-resolution ocean-surface temperature data obtained by the VHRR onboard a NOAA-NESS polar-orbiting satellite, the present study demonstrates that the computed surface stress variation bears a striking resemblance to the measured radar cross-section variations.

The contribution of simple random sampling to observed variations in faecal egg counts.

PubMed

Torgerson, Paul R; Paul, Michaela; Lewis, Fraser I

2012-09-10

It has been over 100 years since the classical paper published by Gosset in 1907, under the pseudonym "Student", demonstrated that yeast cells suspended in a fluid and measured by a haemocytometer conformed to a Poisson process. Similarly parasite eggs in a faecal suspension also conform to a Poisson process. Despite this there are common misconceptions how to analyse or interpret observations from the McMaster or similar quantitative parasitic diagnostic techniques, widely used for evaluating parasite eggs in faeces. The McMaster technique can easily be shown from a theoretical perspective to give variable results that inevitably arise from the random distribution of parasite eggs in a well mixed faecal sample. The Poisson processes that lead to this variability are described and illustrative examples of the potentially large confidence intervals that can arise from observed faecal eggs counts that are calculated from the observations on a McMaster slide. Attempts to modify the McMaster technique, or indeed other quantitative techniques, to ensure uniform egg counts are doomed to failure and belie ignorance of Poisson processes. A simple method to immediately identify excess variation/poor sampling from replicate counts is provided. Copyright © 2012 Elsevier B.V. All rights reserved.

Seasonal variations of infrasonic arrivals from long-term ground truth observations in Nevada and implication for event location

NASA Astrophysics Data System (ADS)

Negraru, Petru; Golden, Paul

2017-04-01

Long-term ground truth observations were collected at two infrasound arrays in Nevada to investigate how seasonal atmospheric variations affect the detection, traveltime and signal characteristics (azimuth, trace velocity, frequency content and amplitudes) of infrasonic arrivals at regional distances. The arrays were located in different azimuthal directions from a munition disposal facility in Nevada. FNIAR, located 154 km north of the source has a high detection rate throughout the year. Over 90 per cent of the detonations have traveltimes indicative of stratospheric arrivals, while tropospheric waveguides are observed from only 27 per cent of the detonations. The second array, DNIAR, located 293 km southeast of the source exhibits strong seasonal variations with high stratospheric detection rates in winter and the virtual absence of stratospheric arrivals in summer. Tropospheric waveguides and thermospheric arrivals are also observed for DNIAR. Modeling through the Naval Research Laboratory Ground to Space atmospheric sound speeds leads to mixed results: FNIAR arrivals are usually not predicted to be present at all (either stratospheric or tropospheric), while DNIAR arrivals are usually correctly predicted, but summer arrivals show a consistent traveltime bias. In the end, we show the possible improvement in location using empirically calibrated traveltime and azimuth observations. Using the Bayesian Infrasound Source Localization we show that we can decrease the area enclosed by the 90 per cent credibility contours by a factor of 2.5.

Slope topography-induced spatial variation correlation with observed building damages in Corso during the May 21, 2003, M w 6.8, Boumerdes earthquake (Algeria)

NASA Astrophysics Data System (ADS)

Messaoudi, Akila; Laouami, Nasser; Mezouar, Nourredine

2017-07-01

During the May 21, 2003 M w 6.8 Boumerdes earthquake, in the "Cité des 102 Logements" built on a hilltop, in Corso, heavy damages were observed: near the crest, a four-story RC building collapsed while others experienced severe structural damage and far from the crest, slight damage was observed. In the present paper, we perform a 2D slope topography seismic analysis and investigate its effects on the response at the plateau as well as the correlation with the observed damage distribution. A site-specific seismic scenario is used involving seismological, geological, and geotechnical data. 2D finite element numerical seismic study of the idealized Corso site subjected to vertical SV wave propagation is carried out by the universal code FLUSH. The results highlighted the main factors that explain the causes of block collapse, located 8-26 m far from the crest. These are as follows: (i) a significant spatial variation of ground response along the plateau due to the topographic effect, (ii) this spatial variation presents high loss of coherence, (iii) the seismic ground responses (PGA and response spectra) reach their maxima, and (iv) the fundamental frequency of the collapsed blocks coincides with the frequency content of the topographic component. For distances far from the crest where slight damages were observed, the topographic contribution is found negligible. On the basis of these results, it is important to take into account the topographic effect and the induced spatial variability in the seismic design of structures sited near the crest of slope.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed through a Nonuniform Interstellar Medium

NASA Astrophysics Data System (ADS)

Huang, X.; Aldering, G.; Biederman, M.; Herger, B.

2017-11-01

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (≳ 10 {pc}) will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent widths, and of extinction, would be small. As a result, we conclude that nonuniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power-law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed Through Non-uniform Interstellar Medium

NASA Astrophysics Data System (ADS)

Huang, Xiaosheng; Aldering, Gregory; Biederman, Moriah; Herger, Brendan

2018-01-01

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (>~ 10 pc) will translate to much smaller fluctuations on the scales of a SN photosphere. Therefore the typical amplitude of time variation due to non-uniform ISM, of absorption equivalent widths and of extinction, would be small. As a result, we conclude that non-uniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

Brightness Variations in the Solar Atmosphere as Seen by SOHO

NASA Astrophysics Data System (ADS)

Brkovic, A.; Rüedi, I.; Solanki, S. K.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.; Harrison, R.; Fludra, A.

We present preliminary results of a statistical analysis of the brightness variations of solar features at different levels in the solar atmosphere. We observed quiet Sun regions at disc centre using the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and Heliospheric Observatory (SOHO). We find significant variability at all time scales in all parts of the quiet Sun, from darkest intranetwork to brightest network. Such variations are observed simultaneously in the chromospheric He I 584.33 Angstroms (2 \\cdot 10^4 K) line, the transition region O V 629.74 Angstroms (2.5 \\cdot 10^5 K) and coronal Mg IX 368.06 Angstroms (10^6 K) line. The relative variability is independent of brightness and most of the variability appears to take place on time scales longer than 5 minutes for all 3 spectral lines. No significant differences are observed between the different data sets.

Diurnal variations of BrONO2 observed by MIPAS-B in the Arctic, at mid-latitudes, and in the Tropics

NASA Astrophysics Data System (ADS)

Wetzel, Gerald; Oelhaf, Hermann; Höpfner, Michael; Friedl-Vallon, Felix; Ebersoldt, Andreas; Gulde, Thomas; Kazarski, Sebastian; Kirner, Oliver; Kleinert, Anne; Maucher, Guido; Nordmeyer, Hans; Orphal, Johannes; Ruhnke, Roland; Sinnhuber, Björn-Martin

2017-04-01

Despite being much less abundant, the contribution of bromine to stratospheric ozone depletion is similar to that of chlorine. Moreover, against the background of abating levels of chlorine in the stratosphere, bromine is important due to its natural sources. The two major inorganic bromine (Bry) species in the lower stratosphere are bromine oxide (BrO) and bromine nitrate (BrONO2). The relative abundances of these molecules are mainly controlled by photochemical processes. The first stratospheric measurements of the diurnal variation of BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68°N, Sweden) inside the stratospheric polar vortices in January 2010 and March 2011 where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 22 parts per trillion by volume (pptv) were detected in the late winter 2011 in the absence of polar stratospheric clouds (PSC). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 partly due to heterogeneous destruction of BrONO2 on PSC particles. A further balloon flight took place at mid-latitudes from Timmins (49°N, Canada) in September 2014. Mean BrONO2 mixing ratios of 23 pptv were observed after sunset in the altitude region between 22 and 29 km. Day- and nighttime profiles of BrONO2 were also inferred from limb emission spectra recorded during a tropical balloon flight from Teresina (5°S, Brazil). Significant differences of the stratospheric BrONO2 amount with up to 23 pptv during night and up to 12 pptv during day were found. Measurements are discussed in comparison to a multi-year simulation performed with the Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). The combination of model simulations with MIPAS-B measurements gives an estimate of stratospheric total inorganic bromine.

Phenotypic variation in a significant spore character in Kudoa (Myxosporea: Multivalvulida) species infecting brain tissue.

PubMed

Burger, Mieke A A; Adlard, Robert D

2010-10-01

Some Kudoa species display variations in the number of polar capsules in spores within an individual pseudocyst. Nonetheless, there is usually a dominant morphotype which forms a significant element of diagnosis. In 2007, a Kudoa isolate from whiting (spores with 5 (dominant) or 6 (minor) polar capsules) was characterized by Burger et al. (2007) as being 100% identical in SSU rDNA to Kudoa yasunagai (spores with 7 polar capsules) from a halibut, despite its obvious morphological differences. The authors hypothesized that either SSU rDNA had reached its level of resolution or that the genetic identity revealed conspecificity. To further investigate these hypotheses, SSU and LSU rDNA sequence data were coupled with principal components, correlation, and regression analyses of morphometric data from different kudoid isolates that infect brain tissue to determine the relationships between spore morphotypes and different kudoid isolates. The trends in morphometrics between the spores of particular isolates were so similar that it was concluded that the molecular results did indicate conspecificity rather than SSU reaching its level of resolution. This phenotypic influence on a significant diagnostic character within the Kudoidae has a major impact on the diagnosis of this, and potentially other, pathogenic species.

Inter-annual variation of the surface temperature of tropical forests from SSM/I observations

NASA Astrophysics Data System (ADS)

Gao, H.; Fu, R.; Li, W.; Zhang, S.; Dickinson, R. E.

2014-12-01

Land surface temperatures (LST) within tropical rain forests contribute to climate variation, but observational data are very limited in these regions. In this study, all weather canopy sky temperatures were retrieved using the passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) over the Amazon and Congo rainforests. The remote sensing data used were collected from 1996 to 2012 using two separate satellites—F13 (1996-2009) and F17 (2007-2012). An inter-sensor calibration between the brightness temperatures collected by the two satellites was conducted in order to ensure consistency amongst the instruments. The interannual changes of LST associated with the dry and wet anomalies were investigated in both regions. The dominant spatial and temporal patterns for inter-seasonal variations of the LST over the tropical rainforest were analyzed, and the impacts of droughts and El Niños (on LST) were also investigated. The remote sensing results suggest that the morning LST is mainly controlled by atmospheric humidity (which controls longwave radiation) whereas the late afternoon LST is controlled by solar radiation.

Novel quality indicators for metastatic colorectal cancer management identify significant variations in these measures across treatment centers in Australia.

PubMed

Turner, Natalie Heather; Wong, Hui-Li; Field, Kathryn; Wong, Rachel; Shapiro, Jeremy; Yip, Desmond; Nott, Louise; Tie, Jeanne; Kosmider, Suzanne; Tran, Ben; Desai, Jayesh; McKendrick, Joseph; Zimet, Allan; Richardson, Gary; Iddawela, Mahesh; Gibbs, Peter

2015-09-01

Defining multidisciplinary quality of care indicators (QCIs) for metastatic colorectal cancer (mCRC) could improve understanding of variations in routine practice care. This may identify areas of below-average performance, which could then be addressed by clinicians to improve the quality of care delivered. This study aimed to define a panel of QCIs in mCRC and, based on these QCIs, to evaluate quality of care across multiple Australian sites. A panel of clinicians with expertise in colorectal cancer defined evidence-based or best practice-based QCIs relevant to the routine multidisciplinary management of mCRC patients through structured consensus discussion. Related data were extracted from the Treatment of Recurrent and Advanced Colorectal Cancer (TRACC) registry, a prospectively maintained database recording comprehensive details on consecutive mCRC patients across multiple Australian hospitals. Variations in QCIs across sites were explored. Of 13 QCIs defined, data related to 10 were reliably extracted from TRACC. Analysis of data on 1276 patients across 10 sites demonstrated low rates of screening for hereditary nonpolyposis colorectal cancer in young patients and significant variation in surveillance-detected recurrences, lung resection rates and palliative chemotherapy use. Exploratory analyses suggested correlation between liver resection rates and survival. We have defined a novel set of mCRC QCIs and have demonstrated wide variation in the quality of care of mCRC across multiple Australian sites. With further validation to confirm a direct correlation between QCI and patient outcomes, these QCIs could be applied to improve the quality of care received by all mCRC patients. © 2015 Wiley Publishing Asia Pty Ltd.

Multi-scale Drivers of Variations in Atmospheric Evaporative Demand Based on Observations and Physically-based Modeling

NASA Astrophysics Data System (ADS)

Peng, L.; Sheffield, J.; Li, D.

2015-12-01

Evapotranspiration (ET) is a key link between the availability of water resources and climate change and climate variability. Variability of ET has important environmental and socioeconomic implications for managing hydrological hazards, food and energy production. Although there have been many observational and modeling studies of ET, how ET has varied and the drivers of the variations at different temporal scales remain elusive. Much of the uncertainty comes from the atmospheric evaporative demand (AED), which is the combined effect of radiative and aerodynamic controls. The inconsistencies among modeled AED estimates and the limited observational data may originate from multiple sources including the limited time span and uncertainties in the data. To fully investigate and untangle the intertwined drivers of AED, we present a spectrum analysis to identify key controls of AED across multiple temporal scales. We use long-term records of observed pan evaporation for 1961-2006 from 317 weather stations across China and physically-based model estimates of potential evapotranspiration (PET). The model estimates are based on surface meteorology and radiation derived from reanalysis, satellite retrievals and station data. Our analyses show that temperature plays a dominant role in regulating variability of AED at the inter-annual scale. At the monthly and seasonal scales, the primary control of AED shifts from radiation in humid regions to humidity in dry regions. Unlike many studies focusing on the spatial pattern of ET drivers based on a traditional supply and demand framework, this study underlines the importance of temporal scales when discussing controls of ET variations.

Annual and inter-annual variations of 6.5-day-planetary-waves in MLT observed by TIMED/SABER

NASA Astrophysics Data System (ADS)

Huang, Yingying; Li, Huijun; Li, Chongyin; Zhang, Shaodong

2017-04-01

Annual and inter-annual variations of 6.5DWs in 20-110 km, 52°S-52°N, 2002-2016 are studied by using v2.0 TIMED/SABER kinetic temperature data. Firstly, global annual variations of 6.5DW's spectral power and amplitudes are obtained. Strong wave amplitudes emerge in 30°S/N-50°S/N, and peaks in altitude separate in stratosphere (40-50 km), mesosphere (80-90 km) and the lower thermosphere (100-110 km), respectively. Their annual variations are similar in both hemispheres, but different in altitude. In 40-50 km, the annual maximums emerge mostly in winters: Dec.-Jan. in the NH and Jul.-Aug. in the SH. In MLT, annual peaks arise twice in each half of year. In 80-90 km, they're mainly in equinoctial seasons and winters: May, Aug.-Sep. and Jan. in the NH and Feb., Nov. and May in the SH. In 100-110 km, they emerge mainly in equinoctial seasons: Apr.-May and Aug.-Sep. in the NH and Feb.-Mar. and Oct.-Nov. in the SH. Then, inter-annual variations of 6.5DW amplitudes during the 14-year period are studied. Frequency spectra of monthly-mean amplitudes show that, main dynamics in long-term variations of 6.5DWs are AO and SAO in both hemispheres. Besides, QBO are visible in both hemispheres and 4-month period signals are noticed in the NH in MLT. Amplitudes of SAO, AO and QBO are obtained by bandpass filter. Their amplitudes are comparable in stratosphere and mesosphere, and QBO signals are weaker than the others in the LT. Vertical variations both of SAO and AO amplitudes are very stable. AO structures have little inter-annual changes, while inter-annual variations of SAO are significant and are related with 6.5DW. It means that annual and inter-annual variations of 6.5DW are mainly controlled by AO and SAO, respectively. Although QBO signals are weaker and their variations are less regular than AO and SAO, their phases seems to relate with inter-annual variations of 6.5DW as well.

Apatite in carbonatitic rocks: Compositional variation, zoning, element partitioning and petrogenetic significance

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Zaitsev, Anatoly N.; Couëslan, Christopher; Xu, Cheng; Kynický, Jindřich; Mumin, A. Hamid; Yang, Panseok

2017-03-01

-spectroscopy proved inconclusive for apatites with small P-site deficiencies and other substituent elements in this site. Indicator REE ratios sensitive to redox conditions (δCe, δEu) and hydrothermal overprint (δY) form a fairly tight cluster of values (0.8-1.3, 0.8-1.1 and 0.6-0.9, respectively) and may be used in combination with trace-element abundances for the development of geochemical exploration tools. Hydrothermal apatite forms in carbonatites as the product of replacement of primary apatite, or is deposited in fractures and interstices as euhedral crystals and aggregates associated with typical late-stage minerals (e.g., quartz and chlorite). Hydrothermal apatite is typically depleted in Sr, REE, Mn and Th, but enriched in F (up to 4.8 wt.%) relative to its igneous precursor, and also differs from the latter in at least some of key REE ratios [e.g., shows (La/Yb)cn ≤ 25, or a negative Ce anomaly]. The only significant exception is Sr(± REE,Na)-rich replacement zones and overgrowths on igneous apatite from some dolomite(-bearing) carbonatites. Their crystallization conditions and source fluid appear to be very different from the more common Sr-REE-depleted variety. Based on the new evidence presented in this work, trace-element partitioning between apatite and carbonatitic magmas, phosphate solubility in these magmas, and compositional variation of apatite-group minerals from spatially associated carbonatitic rocks are critically re-evaluated.

Effects of the Observed Meridional Flow Variations since 1996 on the Sun's Polar Fields

NASA Technical Reports Server (NTRS)

Hathaway, David; Upton, Lisa

2013-01-01

The cause of the low and extended minimum in solar activity between Sunspot Cycles 23 and 24 was the small size of Sunspot Cycle 24 itself - small cycles start late and leave behind low minima. Cycle 24 is small because the polar fields produced during Cycle 23 were substantially weaker than those produced during the previous cycles and those (weak) polar fields are the seeds for the activity of the following cycle. The polar fields are produced by the latitudinal transport of magnetic flux that emerged in low-latitude active regions. The polar fields thus depend upon the details of both the flux emergence and the flux transport. We have measured the flux transport flows (differential rotation, meridional flow, and supergranules) since 1996 and find systematic and substantial variation in the meridional flow alone. Here we present experiments using a Surface Flux Transport Model in which magnetic field data from SOHO/MDI and SDO/HMI are assimilated into the model only at latitudes between 45-degrees north and south of the equator (this assures that the details of the active region flux emergence are well represented). This flux is then transported in both longitude and latitude by the observed flows. In one experiment the meridional flow is given by the time averaged (and north-south symmetric) meridional flow profile. In the second experiment the time-varying and north-south asymmetric meridional flow is used. Differences between the observed polar fields and those produced in these two experiments allow us to ascertain the effects of these meridional flow variations on the Sun s polar fields.

T he Analysis of the seasonal variations of equatorial plasma bubble, occurrence observed from Oukaimeden Observatory, Morroco

NASA Astrophysics Data System (ADS)

Amine, Lagheryeb; Zouhair, Benkhaldoun; Jonathan, Makela; Mohamed, Kaab; Aziza, Bounhir; Brian, Hardin; Dan, Fisher; Tmuthy, Duly

2016-04-01

T he Analysis of the seasonal variations of equatorial plasma bubble, occurrence using the 630.0 nm airglow images collected by the PICASSO imager deployed at the Oukkaimden observatory in Morocco. Data have been taken since November 2013 to december 2015. We show the monthly average of appearance of EPBs. A maximum probability for bubble development is seen in the data in January and between late February and early March. We also observe that there are a maximum period of appearance where the plasma is observed (3-5 nights successivies) and we will discuss its connection with the solar activity in storm time. Future analysis will compare the probability of bubble occurrence in our site with the data raised in other observation sites.

Constraining the variation of the fine-structure constant with observations of narrow quasar absorption lines

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

Songaila, A.; Cowie, L. L., E-mail: acowie@ifa.hawaii.edu

2014-10-01

The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure inmore » even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10{sup –5}, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (– 0.59 ± 0.55) × 10{sup –5} in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10{sup –5}, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (– 0.47 ± 0.53) × 10{sup –5}. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (– 0.01 ± 0.26) × 10{sup –5}. We conclude that spectroscopic measurements

Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

NASA Astrophysics Data System (ADS)

Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp

Mass-induced sea level variations in the Red Sea from steric-corrected altimetry, GRACE, in-situ bottom pressure records, and hydrographic observations

NASA Astrophysics Data System (ADS)

Feng, Wei; Lemoine, Jean-Michel; Zhong, Min; Xu, Houze

2014-05-01

An annual amplitude of ~18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from steric-corrected altimetry and the Gravity Recovery and Climate Experiment (GRACE) satellites from 2003 to 2011, which dominates the mean sea level in the region. Seawater mass variations here generally reach maximum in late January/early February. The steric component of SLV calculated from oceanographic temperature and salinity data is relatively small and peaks about seven months later than mass variations. The phase difference between the steric SLV and the mass-induced SLV indicates that when the Red Sea gains the mass from inflow water in winter, the steric SLV fall, and vice versa in summer. In-situ bottom pressure records in the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. Furthermore, we compare the horizontal water mass flux in the Red Sea from steric-corrected altimetry and GRACE with that estimated from hydrographic observations.

Climate variation explains a third of global crop yield variability

PubMed Central

Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

2015-01-01

Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32–39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability. PMID:25609225

Observations of Co-variation in Cloud Properties and their Relationships with Atmospheric State

NASA Astrophysics Data System (ADS)

Sinclair, K.; van Diedenhoven, B.; Fridlind, A. M.; Arnold, T. G.; Yorks, J. E.; Heymsfield, G. M.; McFarquhar, G. M.; Um, J.

2017-12-01

Radiative properties of upper tropospheric ice clouds are generally not well represented in global and cloud models. Cloud top height, cloud thermodynamic phase, cloud optical thickness, cloud water path, particle size and ice crystal shape all serve as observational targets for models to constrain cloud properties. Trends or biases in these cloud properties could have profound effects on the climate since they affect cloud radiative properties. Better understanding of co-variation between these cloud properties and linkages with atmospheric state variables can lead to better representation of clouds in models by reducing biases in their micro- and macro-physical properties as well as their radiative properties. This will also enhance our general understanding of cloud processes. In this analysis we look at remote sensing, in situ and reanalysis data from the MODIS Airborne Simulator (MAS), Cloud Physics Lidar (CPL), Cloud Radar System (CRS), GEOS-5 reanalysis data and GOES imagery obtained during the Tropical Composition, Cloud and Climate Coupling (TC4) airborne campaign. The MAS, CPL and CRS were mounted on the ER-2 high-altitude aircraft during this campaign. In situ observations of ice size and shape were made aboard the DC8 and WB57 aircrafts. We explore how thermodynamic phase, ice effective radius, particle shape and radar reflectivity vary with altitude and also investigate how these observed cloud properties vary with cloud type, cloud top temperature, relative humidity and wind profiles. Observed systematic relationships are supported by physical interpretations of cloud processes and any unexpected differences are examined.

Storm-time variation of radiative cooling by Nitric Oxide as observed by TIMED-SABER and GUVI

NASA Astrophysics Data System (ADS)

Sunil Krishna, M. V.; Bharti, G.; Bag, T.

2017-12-01

The variation of O/N2 and nitric oxide radiative emission flux exiting thermosphere have been studied over northern hemisphere during the super-storm event of November 7-12, 2004. The data have been obtained from GUVI and SABER onboard the NASA's TIMED satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2 and N2 densities have been calculated by using NRLMSISE-00 model over a mid-latitude location (55oN,180oE). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The SABER retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and NOEM model. Both these suggest huge increase in NO density during the storm which is required to account the changes in NO radiative flux.

Spatio-temporal variation of methane over Indian region: Seasonal and inter-annual variation .

NASA Astrophysics Data System (ADS)

M, K.; Nair, P. R.

2015-12-01

Methane (CH4) has an important role in the radiation budget and chemistry in the lower and middle atmosphere as a greenhouse and reactive trace gas. The rapid developments in the agriculture and industry over India have lead to the emission of many pollutants like CO, O3, CH4, CO2, SO2 etc into the atmosphere. However, their sources, sinks and concentration levels are poorly understood because of the lack of systematic sampling and monitoring. The advent of satellite remote sensing has helped to analyze the chemical composition of atmosphere with good spatial coverage especially over tropical region which was poorly sampled with the existing surface network. This work attempts an analysis of spatial distribution, seasonal cycle and inter annual variation of CH4 over Indian region during 2003-2009 using SCIAMACHY data onboard ENVISAT. Column CH4 varies from 1740-1890 ppbv over Indian region with distinct spatial and temporal features. We observed a dependence of seasonal CH4 variation on rice cultivation, convective activities and changes in boundary layer characteristics. The comparative study using satellite, aircraft and surface measurement shown CH4 has non-homogeneity in its distribution and seasonal variation in different layers of atmosphere. A comparative study of CH4 at different hot spot regions over the globe was carried out which showed prominent hemispherical variations. Large spread in column CH4 was observed at India and Chinese region compared to other regions with a significant seasonal variability. This study points to the blending of satellite, aircraft and surface measurements for the realization of regional distribution of CH4.

Zonal Drift Variations and Suppression of Ionospheric Scintillation During St. Patrick's Day Storm Observed by Pingtung SCINDA Station in Taiwan

NASA Astrophysics Data System (ADS)

Su, S. Y.; Nayak, C.; Tsai, L. C.; Caton, R. G.; Groves, K. M.

2016-12-01

Variations of zonal drift and ionospheric VHF scintillations observed by a SCINDA station in Southern Taiwan during the St. Patrick's day geomagnetic storm are studied. Although scintillations were observed for 6 consecutive days before the storm, they were absence during the storm period. Data from VHF receivers, ionosonde and in situ plasma density observations from ESA's SWARM constellation are used to study the ionospheric irregularity/scintillation events in the Taiwanese sector to compare with what happened in the Indian sectors. The absence of scintillation in the Taiwanese sector during the storm period seems to be caused by a reduced pre-reversal enhancement (PRE) electric field from a westward prompt-penetration electric field (PPEF) during the storm. A low post-sunset ionosphere thus becomes unfavorable for the Rayleigh-Taylor instability to occur. On the contrary, the PPEFs were found to strongly enhance the PRE electric field in the Indian sector to cause the ionospheric irregularities/scintillations in the post-sunset sector. Zonal drift variations during the storm time are also discussed in conjunction with the irregularity/scintillation occurrences.

Long-term observations of seafloor pressure variations at Lucky Strike volcano, Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Ballu, V.; de Viron, O.; Crawford, W. C.; Cannat, M.; Escartin, J.

2012-12-01

Lucky Strike volcano is a segment-center volcano on the Mid-Atlantic Ridge at 37°N. Extensive faulting reveals an important tectonic component in its formation, while a seismically imaged axial magma chamber reflector and active high-temperature hydrothermal vents reveal an important present-day magmatic component. Lucky Strike volcano has been the subject of long-term multidisciplinary seafloor observations to understand relations between magmatism, tectonism, hydrothermal circulation, biology and chemistry as part of the MoMAR (Monitoring of the Mid-Atlantic Ridge) program. Absolute pressure gauges have been recording on the volcano since 2007, to identify deformations associated with tectonism or magmatism. Deformation measurements are one of the principal means of determining volcanic activity, but the amount of deformation associated with volcanic events varies greatly between different volcanos. We installed two sites: one in the volcano's summit "lava lake" (1700 m depth) and another on the volcano's flank (2000 m depth). Pressure is recorded every thirty seconds, giving a data set that constrains movements on the scale from minutes to years. No major deformation event has been detected by the instruments since their installation (nor has any significant tectonic event been detected by a seismic network in place since 2007), so we concentrate here on the detection limit of these instruments and on variations in the long-period ocean wave climate. Using the statistical characteristics of the pressure signal, modeled by an auto-regressive process, we determine that a movement between the sites of 1 cm over less than 10 days is detectable; the detection threshold decreases to about 0.2 cm for the shortest time periods and increases for longer time periods due to instrumental drift. We compare the statistical characteristics and short- and long-term sensitivity of three different types of gauges used during the experiment: Paroscientific standard

Epigenetic Variation in Mangrove Plants Occurring in Contrasting Natural Environment

PubMed Central

Lira-Medeiros, Catarina Fonseca; Parisod, Christian; Fernandes, Ricardo Avancini; Mata, Camila Souza; Cardoso, Monica Aires; Ferreira, Paulo Cavalcanti Gomes

2010-01-01

Background Epigenetic modifications, such as cytosine methylation, are inherited in plant species and may occur in response to biotic or abiotic stress, affecting gene expression without changing genome sequence. Laguncularia racemosa, a mangrove species, occurs in naturally contrasting habitats where it is subjected daily to salinity and nutrient variations leading to morphological differences. This work aims at unraveling how CpG-methylation variation is distributed among individuals from two nearby habitats, at a riverside (RS) or near a salt marsh (SM), with different environmental pressures and how this variation is correlated with the observed morphological variation. Principal Findings Significant differences were observed in morphological traits such as tree height, tree diameter, leaf width and leaf area between plants from RS and SM locations, resulting in smaller plants and smaller leaf size in SM plants. Methyl-Sensitive Amplified Polymorphism (MSAP) was used to assess genetic and epigenetic (CpG-methylation) variation in L. racemosa genomes from these populations. SM plants were hypomethylated (14.6% of loci had methylated samples) in comparison to RS (32.1% of loci had methylated samples). Within-population diversity was significantly greater for epigenetic than genetic data in both locations, but SM also had less epigenetic diversity than RS. Frequency-based (GST) and multivariate (βST) methods that estimate population structure showed significantly greater differentiation among locations for epigenetic than genetic data. Co-Inertia analysis, exploring jointly the genetic and epigenetic data, showed that individuals with similar genetic profiles presented divergent epigenetic profiles that were characteristic of the population in a particular environment, suggesting that CpG-methylation changes may be associated with environmental heterogeneity. Conclusions In spite of significant morphological dissimilarities, individuals of L. racemosa from salt

Seasonal variation in physiological condition of Amblema plicata in the Upper Mississippi River

USGS Publications Warehouse

Monroe, E.M.; Newton, T.J.

2001-01-01

Measures of physiological condition are being used as sub-lethal endpoints in studies with unionids exposed to a variety of stressors, yet the natural seasonal variation in these measures are largely undocumented. We measured concentrations of glycogen in foot and mantle tissue and a tissue condition index (TCI) in Amblema plicata (Say 1817), about monthly, for 2 years in mussels that were: (1) obtained directly from the Upper Mississippi River (riverine group); and (2) relocated from the river into an artificial pond (relocated group). In both groups, we observed significant seasonal variation in all physiological indicators. Seasonal variation in glycogen was 72% in mantle and 52% in foot tissue and paralleled reproductive activity in this short-term breeder. In the relocated group, most of the variation in glycogen occurred during the first six months after relocation, suggesting that handling stress may have been a contributing factor. The significant seasonal variation in the TCI paralleled glycogen in riverine mussels. We observed tissue-specific differences in glycogen in the riverine group, but not in the relocated group. These data suggest that an interaction of environmental and biological factors influence the energetic status of mussels in natural populations. A better understanding of this variation is needed to interpret changes in physiological condition due to stressors such as relocation.

Age and sex variation in serum albumin concentration: an observational study.

PubMed

Weaving, Gary; Batstone, Gifford F; Jones, Richard G

2016-01-01

In the UK, a common reference interval for serum albumin is widely used irrespective of age or sex. Implicit in this is that laboratories produce analytically similar results. This paper challenges the validity of this approach. A three-week collection of results sent to all primary care centres in England has been analysed by age, sex and laboratory. In all, 1,079,193 serum albumin reports were included in this analysis. The mean population serum albumin concentration increases to peak at around age 20 years and then decreases with increasing age. Values in females decrease more rapidly but become close to male values at 60 years. The variation between laboratories was large and potentially clinically significant. Reference intervals for serum albumin should be stratified by age and sex. Until there is greater methodological standardization, laboratories should determine their own reference intervals and not accept a single consensus reference interval. © The Author(s) 2015.

Observed variations in U.S. frost timing linked to atmospheric circulation patterns

NASA Astrophysics Data System (ADS)

Strong, Courtenay; McCabe, Gregory J.

2017-05-01

Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25-48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

Observed variations in U.S. frost timing linked to atmospheric circulation patterns

USGS Publications Warehouse

Strong, Courtenay; McCabe, Gregory J.

2017-01-01

Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25–48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

Observed variations in U.S. frost timing linked to atmospheric circulation patterns.

PubMed

Strong, Courtenay; McCabe, Gregory J

2017-05-23

Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25-48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

Task variation during simulated, repetitive, low-intensity work--influence on manifestation of shoulder muscle fatigue, perceived discomfort and upper-body postures.

PubMed

Luger, Tessy; Bosch, Tim; Hoozemans, Marco; de Looze, Michiel; Veeger, Dirkjan

2015-01-01

Work-related musculoskeletal disorders are increasing due to industrialisation of work processes. Task variation has been suggested as potential intervention. The objectives of this study were to investigate, first, the influence of task variation on electromyographic (EMG) manifestations of shoulder muscle fatigue and discomfort; second, noticeable postural shoulder changes over time; third, if the association between task variation and EMG might be biased by postural changes. Outcome parameters were recorded using multichannel EMG, Optotrak and the Borg scale. Fourteen participants performed a one-hour repetitive Pegboard task in one continuous and two interrupted conditions with rest and a pick-and-place task, respectively. Manifestations of shoulder muscle fatigue and discomfort feelings were observed throughout the conditions but these were not significantly influenced by task variation. After correction for joint angles, the relation between task variation and EMG was significantly biased but significant effects of task variation remained absent. Comparing a one-hour continuous, repetitive Pegboard task with two interrupted conditions revealed no significant influences of task variation. We did observe that the relation between task variation and EMG was biased by posture and therefore advise taking account for posture when investigating manifestations of muscle fatigue in assembly tasks.

Longitudinal Variations in the Variability of Spread F Occurrence

NASA Astrophysics Data System (ADS)

Groves, K. M.; Bridgwood, C.; Carrano, C. S.

2017-12-01

The complex dynamics of the equatorial ionosphere have attracted the interest and attention of researchers for many decades. The relatively local processes that give rise to large meridional gradients have been well documented and the associated terminology has entered the common lexicon of ionospheric research (e.g., fountain effect, equatorial anomaly, bubbles, Spread F). Zonal variations have also been noted, principally at the level of determining longitudinal differences in seasonal activity patterns. Due to a historical lack of high resolution ground-based observations at low latitudes, the primary source of data for such analyses has been space-based observations from satellites such as ROCSAT, DMSP, C/NOFS that measure in situ electron density variations. An important longitudinal variation in electron density structure associated with non-migrating diurnal tides was discovered by Immel et al. in 2006 using data from the FUV sensor aboard the NASA IMAGE satellite. These satellite observations have been very helpful in identifying the structural characteristics of the equatorial ionosphere and the occurrence of Spread F, but they provide little insight into variations in scintillation features and potential differences in bubble development characteristics. Moreover space-based studies tend towards the statistics of occurrence frequency over periods of weeks to months. A recent analysis of daily spread F occurrence as determined by low latitude VHF scintillation activity shows that statistical results that are consistent with previous space-based observations, but the level of variability in the occurrence data show marked variations with longitude. For example, the American sector shows very low in-season variability while the African and Asian sectors exhibit true day-to-day variability regardless of seasonal variations. The results have significant implications for space weather as they suggest that long-term forecasts of equatorial scintillation may be

Observer variation in the assessment of root canal curvature.

PubMed

Faraj, S; Boutsioukis, C

2017-02-01

To evaluate the inter- and intra-observer agreement between training/trained endodontists regarding the ex vivo classification of root canal curvature into three categories and its measurement using three quantitative methods. Periapical radiographs of seven extracted human posterior teeth with varying degrees of curvature were exposed ex vivo. Twenty training/trained endodontists were asked to classify the root canal curvature into three categories (<10°, 10-30°, >30°), to measure the curvature using three quantitative methods (Schneider, Weine, Pruett) and to draw angles of 10° or 30°, as a control experiment. The procedure was repeated after six weeks. Inter- and intra-observer agreement was evaluated by the intraclass correlation coefficient and weighted kappa. The inter-observer agreement on the visual classification of root canal curvature was substantial (ICC = 0.65, P < 0.018), but a trend towards underestimation of the angle was evident. Participants modified their classifications both within and between the two sessions. Median angles drawn as a control experiment were not significantly different from the target values (P > 0.10), but the results of individual participants varied. When quantitative methods were used, the inter- and intra-observer agreement on the angle measurements was considerably better (ICC = 0.76-0.82, P < 0.001) than on the radius measurements (ICC = 0.16-0.19, P > 0.895). Visual estimation of root canal curvature was not reliable. The use of computer-based quantitative methods is recommended. The measurement of radius of curvature was more subjective than angle measurement. Endodontic Associations need to provide specific guidelines on how to estimate root canal curvature in case difficulty assessment forms. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Nature and causes of Quaternary climate variation of tropical South America

NASA Astrophysics Data System (ADS)

Baker, Paul A.; Fritz, Sherilyn C.

2015-09-01

This selective review of the Quaternary paleoclimate of the South American summer monsoon (SASM) domain presents viewpoints regarding a range of key issues in the field, many of which are unresolved and some of which are controversial. (1) El Niño-Southern Oscillation variability, while the most important global-scale mode of interannual climate variation, is insufficient to explain most of the variation of tropical South American climate observed in both the instrumental and the paleoclimate records. (2) Significant climate variation in tropical South America occurs on seasonal to orbital (i.e. multi-millennial) time scales as a result of sea-surface temperature (SST) variation and ocean-atmosphere interactions of the tropical Atlantic. (3) Decadal-scale climate variability, linked with this tropical Atlantic variability, has been a persistent characteristic of climate in tropical South America for at least the past half millennium, and likely, far beyond. (4) Centennial-to-millennial climate events in tropical South America were of longer duration and, perhaps, larger amplitude than any observed in the instrumental period, which is little more than a century long in tropical South America. These were superimposed upon both precession-paced insolation changes that caused significant variation in SASM precipitation and eccentricity-paced global glacial boundary conditions that caused significant changes in the tropical South American moisture balance. As a result, river sediment and water discharge increased and decreased across tropical South America, lake levels rose and fell, paleolakes arose and disappeared on the Altiplano, glaciers waxed and waned in the tropical Andes, and the tropical rainforest underwent significant changes in composition and extent. To further evaluate climate forcing over the last glacial cycle (˜125 ka), we developed a climate forcing model that combines summer insolation forcing and a proxy for North Atlantic SST forcing to

The Drop of the Coherence of the Lower Kilohertz Quasi-periodic Brightness Variations is Also Observed in XTE J1701-462

NASA Astrophysics Data System (ADS)

Barret, D.; Bachetti, M.; Miller, M. Coleman

2011-02-01

We investigate the quality factor and root mean square (rms) amplitude of the lower kilohertz quasi-periodic brightness variations (kHz QPOs) from XTE J1701-462, a unique X-ray source which was observed in both the so-called Z and atoll states. Correcting for the frequency drift of the QPO, we show that, as in all sources for which such a correction can be applied, the quality factor and rms amplitude drops sharply above a critical frequency. For XTE J1701-462, this frequency is estimated to be ~800 Hz, where the quality factor reaches a maximum of ~200 (e.g., a value consistent with the one observed from more classical systems, such as 4U 1636-536). Such a drop has been interpreted as the signature of the innermost stable circular orbit, and that interpretation is consistent with the observations we report here. The kHz QPOs in the Z state are much less coherent and lower amplitude than they are in the atoll state. We argue that the change of the QPO properties between the two source states is related to the change of the scale height of the accretion disk; a prediction of the toy model proposed by Barret et al. As a by-product of our analysis, we also increased the significance of the upper kHz QPO detected in the atoll phase up to 4.8σ (single trial significance) and show that the frequency separation (266.5 ± 13.1 Hz) is comparable with the one measured from simultaneous twin QPOs in the Z phase.

Amplitude Variations in Pulsating Red Giants. II. Some Systematics

NASA Astrophysics Data System (ADS)

Percy, J. R.; Laing, J.

2017-12-01

In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.

Variations in achievement of evidence-based, high-impact quality indicators in general practice: An observational study

PubMed Central

West, Robert; Rushforth, Bruno; Stokes, Tim; Glidewell, Liz; Carder, Paul; Faulkner, Simon; Foy, Robbie

2017-01-01

Background There are widely recognised variations in the delivery and outcomes of healthcare but an incomplete understanding of their causes. There is a growing interest in using routinely collected ‘big data’ in the evaluation of healthcare. We developed a set of evidence-based ‘high impact’ quality indicators (QIs) for primary care and examined variations in achievement of these indicators using routinely collected data in the United Kingdom (UK). Methods Cross-sectional analysis of routinely collected, electronic primary care data from a sample of general practices in West Yorkshire, UK (n = 89). The QIs covered aspects of care (including processes and intermediate clinical outcomes) in relation to diabetes, hypertension, atrial fibrillation, myocardial infarction, chronic kidney disease (CKD) and ‘risky’ prescribing combinations. Regression models explored the impact of practice and patient characteristics. Clustering within practice was accounted for by including a random intercept for practice. Results Median practice achievement of the QIs ranged from 43.2% (diabetes control) to 72.2% (blood pressure control in CKD). Considerable between-practice variation existed for all indicators: the difference between the highest and lowest performing practices was 26.3 percentage points for risky prescribing and 100 percentage points for anticoagulation in atrial fibrillation. Odds ratios associated with the random effects for practices emphasised this; there was a greater than ten-fold difference in the likelihood of achieving the hypertension indicator between the lowest and highest performing practices. Patient characteristics, in particular age, gender and comorbidity, were consistently but modestly associated with indicator achievement. Statistically significant practice characteristics were identified less frequently in adjusted models. Conclusions Despite various policy and improvement initiatives, there are enduring inappropriate variations in the

Genetic variation in aryl N-acetyltransferase results in significant differences in the pharmacokinetic and safety profiles of amifampridine (3,4-diaminopyridine) phosphate.

PubMed

Haroldsen, Peter E; Garovoy, Marvin R; Musson, Donald G; Zhou, Huiyu; Tsuruda, Laurie; Hanson, Boyd; O'Neill, Charles A

2015-02-01

The clinical use of amifampridine phosphate for neuromuscular junction disorders is increasing. The metabolism of amifampridine occurs via polymorphic aryl N-acetyltransferase (NAT), yet its pharmacokinetic (PK) and safety profiles, as influenced by this enzyme system, have not been investigated. The objective of this study was to assess the effect of NAT phenotype and genotype on the PK and safety profiles of amifampridine in healthy volunteers (N = 26). A caffeine challenge test and NAT2 genotyping were used to delineate subjects into slow and fast acetylators for PK and tolerability assessment of single, escalating doses of amifampridine (up to 30 mg) and in multiple daily doses (20 mg QID) of amifampridine. The results showed that fast acetylator phenotypes displayed significantly lower C max, AUC, and shorter t 1/2 for amifampridine than slow acetylators. Plasma concentrations of the N-acetyl metabolite were approximately twofold higher in fast acetylators. Gender differences were not observed. Single doses of amifampridine demonstrated dose linear PKs. Amifampridine achieved steady state plasma levels within 1 day of dosing four times daily. No accumulation or time-dependent changes in amifampridine PK parameters occurred. Overall, slow acetylators reported 73 drug-related treatment-emergent adverse events versus 6 in fast acetylators. Variations in polymorphic NAT corresponding with fast and slow acetylator phenotypes significantly affects the PK and safety profiles of amifampridine.

Storm Time Variation of Radiative Cooling by Nitric Oxide as Observed by TIMED-SABER and GUVI

NASA Astrophysics Data System (ADS)

Bharti, Gaurav; Sunil Krishna, M. V.; Bag, T.; Jain, Puneet

2018-02-01

The variation of O/N2 (reference to N2 column density 1017 cm-2) and nitric oxide radiative emission flux exiting the thermosphere have been studied over the Northern Hemisphere during the superstorm event of 7-12 November 2004. The data have been obtained from Global Ultraviolet Imager (GUVI) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the National Aeronautics and Space Administration (NASA)'s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2, and N2 densities have been calculated using NRLMSISE-00 model over a midlatitude location (55°N,180°E). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The collisional excitation of NO with atomic oxygen is the most dominant process for the total cooling rate. The SABER-retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and Nitric Oxide Empirical Model (NOEM) model. Both these suggest a vary large (3-15 times) increase in NO density during the storm, which is required to account the changes in NO radiative flux. A similar kind of enhancement in NO abundance is also noticed in Student Nitric Oxide Explorer observations during intense geomagnetic storms.

Diurnal Variation in Gravity Wave Activity at Low and Middle Latitudes

NASA Technical Reports Server (NTRS)

Andrioli, V. F.; Fritts, D. C.; Batista, P. P.; Clemesha, B. R.; Janches, Diego

2013-01-01

We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7deg S to 53.6deg S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7deg S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6deg S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.

Substorm variations in the magnitude of the magnetic field - AMPTE/CCE observations

NASA Technical Reports Server (NTRS)

Lopez, R. E.; Sibeck, D. G.; Lui, A. T. Y.; Takahashi, K.; Mcentire, R. W.

1988-01-01

Using energetic-particle data taken in the near-earth tail by the AMPTE/Charge Composition Explorer (CCE) satellite, 167 ion injection events, that were essentially dispersionless over a 25-285 keV energy range, were identified, and the variations in the total magnetic field strength over the course of these events were examined in order to determine the dependence of the magnetic field strength on dipole latitude. Results indicate that, during periods of substorm activity, the latitudinal position of the current sheet varied significantly within the 32-deg wedge centered on the dipole equator traversed by CCE. Results also suggest that, even in the near-earth magnetotail out to 8.8 R(E) (CCE apogee), the local field measurements are a better guide to the determination of satellite's position relative to the current shield during a substorm, than is the magnetic latitude.

Mass-induced sea level variations in the Red Sea from GRACE, steric-corrected altimetry, in situ bottom pressure records, and hydrographic observations

NASA Astrophysics Data System (ADS)

Feng, W.; Lemoine, J.-M.; Zhong, M.; Hsu, H. T.

2014-08-01

An annual amplitude of ∼18 cm mass-induced sea level variations (SLV) in the Red Sea is detected from the Gravity Recovery and Climate Experiment (GRACE) satellites and steric-corrected altimetry from 2003 to 2011. The annual mass variations in the region dominate the mean SLV, and generally reach maximum in late January/early February. The annual steric component of the mean SLV is relatively small (<3 cm) and out of phase of the mass-induced SLV. In situ bottom pressure records at the eastern coast of the Red Sea validate the high mass variability observed by steric-corrected altimetry and GRACE. In addition, the horizontal water mass flux of the Red Sea estimated from GRACE and steric-corrected altimetry is validated by hydrographic observations.

Latitudinal variation of the solar limb-darkening function

NASA Astrophysics Data System (ADS)

Kroll, Ronald J.

1994-06-01

In an effort to monitor solar limb-darkening variability, the continuum radiation intensity at 550 nm over the outermost 32 arcseconds of the limb is measured at various solar latitudes. Using the Finite Fourier Transform Definition, the edge location of the Sun is determined for a series of scan amplitudes at each of the observed positions. The differential radius is the difference between edge locations for a fixed pair of scan amplitudes, and is a quantity which characterizes the slope of the solar limb-darkening function. Utilizing the differential radius, such observations offer the possibility of revealing a latitudinal variation of the photospheric temperature gradient and could provide clues to the mechanisms and variability of energy transport out of the Sun. These observations began in 1988 with measurements at 24 separate limb positions and include observations since 1990 when 36 positions were observed. The daily differential radius measurements for each position that is free of contamination from solar active regions are weighted according to the corresponding daily variance and averaged to obtain an overall value at each position for the observing season. The results indicate that during the 1991 observing season, there were regions near 20 deg N latitude and 30 deg S latitude on the Sun where the differential radius values were significantly greater than surrounding regions. This suggests that perturbations to the temperature gradient occur in latitudinally localized regions and persist for at least several months. It is shown that this phenomenon could have the same origin as the observed latitudinal variations of surface temperature and could also speak to the question of a lag time between the cycles of irradiation and magnetic variation.

SO2 columns over China: Temporal and spatial variations using OMI and GOME-2 observations

NASA Astrophysics Data System (ADS)

Huanhuan, Yan; Liangfu, Chen; Lin, Su; Jinhua, Tao; Chao, Yu

2014-03-01

Enhancements of SO2 column amounts due to anthropogenic emission sources over China were shown in this paper by using OMI and GOME-2 observations. The temporal and spatial variations of SO2 columns over China were analyzed for the time period 2005-2010. Beijing and Chongqing showed a high concentration in the SO2 columns, attributable to the use of coal for power generation in China and the characteristic of terrain and meteorology. The reduction of SO2 columns over Beijing and surrounding provinces in 2008 was observed by OMI, which confirms the effectiveness of strict controls on pollutant emissions and motor vehicle traffic before and during 2008 Olympic and Paralympic Games. The SO2 columns over China from GOME-2 (0.2-0.5 DU) were lower than those from OMI (0.6-1 DU), but both showed a decrease in SO2 columns over northern China since 2008 (except an increase in OMI SO2 in 2010).

On the colour variations of negative superhumps

NASA Astrophysics Data System (ADS)

Imada, Akira; Yanagisawa, Kenshi; Kawai, Nobuyuki

2018-06-01

We present simultaneous g΄, Rc, and Ic photometry of the notable dwarf nova ER UMa during the 2011 season. Our photometry revealed that the brightness maxima of negative superhumps coincide with the bluest peaks in g΄ - Ic colour variations. We also found that the amplitudes of negative superhumps are the largest in the g΄ band. These observed properties are significantly different from those observed in early and positive superhumps. Our findings are consistent with a tilted disk model as the light source of negative superhumps.

From Observation to Information: Data-Driven Understanding of on Farm Yield Variation

PubMed Central

Jiménez, Daniel; Dorado, Hugo; Cock, James; Prager, Steven D.; Delerce, Sylvain; Grillon, Alexandre; Andrade Bejarano, Mercedes; Benavides, Hector; Jarvis, Andy

2016-01-01

Agriculture research uses “recommendation domains” to develop and transfer crop management practices adapted to specific contexts. The scale of recommendation domains is large when compared to individual production sites and often encompasses less environmental variation than farmers manage. Farmers constantly observe crop response to management practices at a field scale. These observations are of little use for other farms if the site and the weather are not described. The value of information obtained from farmers’ experiences and controlled experiments is enhanced when the circumstances under which it was generated are characterized within the conceptual framework of a recommendation domain, this latter defined by Non-Controllable Factors (NCFs). Controllable Factors (CFs) refer to those which farmers manage. Using a combination of expert guidance and a multi-stage analytic process, we evaluated the interplay of CFs and NCFs on plantain productivity in farmers’ fields. Data were obtained from multiple sources, including farmers. Experts identified candidate variables likely to influence yields. The influence of the candidate variables on yields was tested through conditional forests analysis. Factor analysis then clustered harvests produced under similar NCFs, into Homologous Events (HEs). The relationship between NCFs, CFs and productivity in intercropped plantain were analyzed with mixed models. Inclusion of HEs increased the explanatory power of models. Low median yields in monocropping coupled with the occasional high yields within most HEs indicated that most of these farmers were not using practices that exploited the yield potential of those HEs. Varieties grown by farmers were associated with particular HEs. This indicates that farmers do adapt their management to the particular conditions of their HEs. Our observations confirm that the definition of HEs as recommendation domains at a small-scale is valid, and that the effectiveness of distinct

Regional variations in the observed morphology and activity of martian linear gullies

NASA Astrophysics Data System (ADS)

Morales, Kimberly Marie; Diniega, Serina; Austria, Mia; Ochoa, Vincent; HiRISE Science and Instrument Team

2017-10-01

The formation mechanism for martian linear gullies has been much debated, because they have been suggested as possible evidence of liquid water on Mars. This class of dune gullies is defined by long (up to 2 km), narrow channels that are relatively uniform in width, and range in sinuosity index. Unlike other gullies on Earth and Mars that end in depositional aprons, linear gullies end in circular depressions referred to as terminal pits. This particular morphological difference, along with the difficulty of identifying a source of water to form these features, has led to several ‘dry’ hypotheses. Recent observations on the morphology, distribution, and present-day activity of linear gullies suggests that they could be formed by subliming blocks of seasonal CO2 ice (“dry ice”) sliding downslope on dune faces. In our study, we aimed to further constrain the possible mechanism(s) responsible for the formation of linear gullies by using HiRISE images to collect morphological data and track seasonal activity within three regions in the southern hemisphere-Hellespontus (~45°S, 40°E), Aonia Terra (~50°S, 290°E), and Jeans (~70°S, 155°E) over the last four Mars years. General similarities in these observations were reflective of the proposed formation process (sliding CO2 blocks) while differences were correlated with regional environmental conditions related to the latitude or general geologic setting. This presentation describes the observed regional differences in linear gully morphology and activity, and investigates how environmental factors such as surface properties and local levels of frost may explain these variations while still supporting the proposed model. Determining the formation mechanism that forms these martian features can improve our understanding of both the climatic and geological processes that shape the Martian surface.

Ecological significance of microsatellite variation in western North American populations of Bromus tectorum

Treesearch

Alisa P. Ramakrishnan; Susan Meyer; Daniel J. Fairbanks; Craig E. Coleman

2006-01-01

Bromus tectorum (cheatgrass or downy brome) is an exotic annual weed that is abundant in western USA. We examined variation in six microsatellite loci for 17 populations representing a range of habitats in Utah, Idaho, Nevada and Colorado (USA) and then intensively sampled four representative populations, for a total sample size of approximately 1000 individuals. All...

Microwave Observations and Modeling of O2 (1-delta(sub g)) and O3 Diurnal Variation in the Mesosphere

NASA Technical Reports Server (NTRS)

Sandor, Brad J.; Clancy, R. Todd; Rusch, David W.; Randall, Cora E.; Eckman, Richard S.; Siskind, David S.; Muhleman, Duane O.

1997-01-01

The first microwave measurements of an electronically excited molecular species in the Earth's atmosphere are presented. Local thermodynamic equilibrium (LTE) rotational line emission from mesospheric O2(1-del(sub g)) was observed at a frequency of 255.01794 GHz (lambda is approx. 1.2 mm), employing the National Radio Astronomy Observatory (NRAO) millimeter facility at Kitt Peak, Arizona (32 N, 111 W). The pressure broadened line shapes of the O2(1-del(sub g)) spectra, which were obtained in January and April 1992 and in January and November 1993, are inverted to retrieve O2(1-del(sub g)) mixing profiles over the 50-70 km altitude region. The observed daytime abundances exceed ozone abundances in the lower mesosphere, which are separately retrieved with coincident O3 spectral line (249.7886 GHz) observations. The January and November 1993 observations are binned into 20-60 min time intervals to study O2(1-del(sub g)) diurnal behavior. Derived abundances of O2(1-del(sub g)) between 50 and 70 km for the four observation dates are 9%, 31%, 3%, and 26%, respectively, each +/- 10% higher than predicted, based on the simple photochemistry of lower mesospheric O2(1-del(sub g)). Modeled variation of [O2(1-del(sub g))] with time of day agrees with observed variation in that the observed difference between model and data abundances is constant throughout the daylight hours of each observation date. Model underprediction Of [02(lAg)] is consistent with similar model underprediction of mesospheric [O3]. A perturbation to the photochemical model that forces decreased ozone chemical loss brings brings both model [O3] and [O2(1-del(sub g))] into agreement with the observations. O2(1-del(sub g)) abundances derived from these 1.2 mm observations agree with [O2(1-del(sub g))] values derived from comparable SME observations of the 1.27 micrometers emission, with assumption of a 3880 sec O2(1-del(sub g)) radiative lifetime. The 6800 sec O2(1-del(sub g)) radiative lifetime proposed by

Strain Variation along Cimandiri Fault, West Java Based on Continuous and Campaign GPS Observation From 2006-2016

NASA Astrophysics Data System (ADS)

Safitri, A. A.; Meilano, I.; Gunawan, E.; Abidin, H. Z.; Efendi, J.; Kriswati, E.

2018-03-01

The Cimandiri fault which is running in the direction from Pelabuhan Ratu to Padalarang is the longest fault in West Java with several previous shallow earthquakes in the last 20 years. By using continues and campaign GPS observation from 2006-2016, we obtain the deformation pattern along the fault through the variation of strain tensor. We use the velocity vector of GPS station which is fixed in stable International Terrestrial Reference Frame 2008 to calculate horizontal strain tensor. Least Square Collocation is applied to produce widely dense distributed velocity vector and optimum scale factor for the Least Square Weighting matrix. We find that the strain tensor tend to change from dominantly contraction in the west to dominantly extension to the east of fault. Both the maximum shear strain and dilatation show positive value along the fault and increasing from the west to the east. The findings of strain tensor variation along Cimandiri Fault indicate the post seismic effect of the 2006 Java Earthquake.

Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

NASA Astrophysics Data System (ADS)

Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

2016-04-01

In Patagonia, the glacial-isostatic adjustment (GIA) to past ice-mass changes (Ivins & James 2004; Klemann et al. 2007) is of particular interest in the context of the determination of the complex regional rheology related to plate subduction in a triple-junction constellation. To further complicate the situation, GIA is overlaid with load deformation not only due to present ice mass changes but also due to water-level changes in the lakes surrounding the icefields and the ocean surrounding Patagonia. These elastic deformations affect the determination of glacial-isostatic uplift rates from GPS observations (Dietrich et al. 2010; Lange et al. 2014). Observations of lake tides and their comparison with the theoretical tidal signal have been used previously to validate predictions of ocean tidal loading and have revealed regional deviations from conventional global elastic earth models (Richter et al. 2009). In this work we investigate the tides and lake-level variations in Lago Argentino, Lago Viedma, Lago San Martín/O'Higgins and Lago Buenos Aires/General Carrera. This allows us to test, among other things, the validity of tidal loading models. We present pressure tide-gauge records from two sites in Lago Argentino extending over 2.5 years (Richter et al. 2015). These observations are complemented by lake-level records provided by the Argentine National Hydrometeorological Network. Based on these lake-level time series the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle exceeding 1 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. In Lago Argentino sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in these lakes are dominated by surface seiches reaching 20 cm in amplitude. A harmonic tidal analysis of the lake

GPS-tracking and colony observations reveal variation in offshore habitat use and foraging ecology of breeding Sandwich Terns

NASA Astrophysics Data System (ADS)

Fijn, R. C.; de Jong, J.; Courtens, W.; Verstraete, H.; Stienen, E. W. M.; Poot, M. J. M.

2017-09-01

Breeding success of seabirds critically depends on their foraging success offshore. However, studies combining at-sea tracking and visual provisioning observations are scarce, especially for smaller species of seabirds. This study is the first in which breeding Sandwich Terns were tracked with GPS-loggers to collect detailed data on foraging habitat use in four breeding seasons. The maximum home range of individual Sandwich Terns comprised approximately 1900 km2 and the average foraging range was 27 km. Trip durations were on average 135 min with average trip lengths of 67 km. Actual foraging behaviour comprised 35% of the time budget of a foraging trip. Substantial year-to-year variation was found in habitat use and trip variables, yet with the exception of 2012, home range size remained similar between years. Food availability, chick age and environmental conditions are proposed as the main driving factors between inter- and intra-annual variations in trip variables. Our multi-method approach also provided geo-referenced information on prey presence and we conclude that future combining of colony observations and GPS-loggers deployments can potentially provide a near complete insight into the feeding ecology of breeding Sandwich Terns, including the behaviour of birds at sea.

Immunogenetic Variation and Differential Pathogen Exposure in Free-Ranging Cheetahs across Namibian Farmlands

PubMed Central

Castro-Prieto, Aines; Wachter, Bettina; Melzheimer, Joerg; Thalwitzer, Susanne; Hofer, Heribert; Sommer, Simone

2012-01-01

Background Genes under selection provide ecologically important information useful for conservation issues. Major histocompatibility complex (MHC) class I and II genes are essential for the immune defence against pathogens from intracellular (e.g. viruses) and extracellular (e.g. helminths) origins, respectively. Serosurvey studies in Namibian cheetahs (Acinonyx juabuts) revealed higher exposure to viral pathogens in individuals from north-central than east-central regions. Here we examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs. Methodology/Principal Findings Genetic variation at MHC I and II loci was assessed through single-stranded conformation polymorphism (SSCP) analysis and sequencing. While the overall allelic diversity did not differ, we observed a high genetic differentiation at MHC class I loci between cheetahs from north-central and east-central Namibia. No such differentiation in MHC class II and neutral markers were found. Conclusions/Significance Our results suggest that MHC class I variation mirrors the variation in selection pressure imposed by viruses in free-ranging cheetahs across Namibian farmland. This is of high significance for future management and conservation programs of this species. PMID:23145096

Three-dimensional analytical model for the spatial variation of the foreshock electron distribution function - Systematics and comparisons with ISEE observations

NASA Technical Reports Server (NTRS)

Fitzenreiter, R. J.; Scudder, J. D.; Klimas, A. J.

1990-01-01

A model which is consistent with the solar wind and shock surface boundary conditions for the foreshock electron distribution in the absence of wave-particle effects is formulated for an arbitrary location behind the magnetic tangent to the earth's bow shock. Variations of the gyrophase-averaged velocity distribution are compared and contrasted with in situ ISEE observations. It is found that magnetic mirroring of solar wind electrons is the most important process by which nonmonotonic reduced electron distributions in the foreshock are produced. Leakage of particles from the magnetosheath is shown to be relatively unimportant in determining reduced distributions that are nonmonotonic. The two-dimensional distribution function off the magnetic field direction is the crucial contribution in producing reduced distributions which have beams. The time scale for modification of the electron velocity distribution in velocity space can be significantly influenced by steady state spatial gradients in the background imposed by the curved shock geometry.

Optical spectrum variations of IL Cep A

NASA Astrophysics Data System (ADS)

Ismailov, N. Z.; Khalilov, O. V.; Bakhaddinova, G. R.

2016-02-01

The results of many-year uniform spectroscopic observations of the Herbig Ae/Be star IL Cep A are presented. Its Hα line has either a single or a barely resolved two-component emission profile. The H β emission line is clearly divided into two components with a deep central absorption. Smooth variations of the observed parameters of individual spectral lines over nine years are observed. The He I λ5876 Å line has a complex absorption profile, probably with superposed emission components. The NaI D1, D2 doublet exhibits weak changes due to variations in the circumstellar envelope. The variations observed in the stellar spectrum can be explained by either binarity or variations of the magnetic field in the stellar disk. Difficulties associated with both these possibilities are discussed.

Macrophytes shape trophic niche variation among generalist fishes.

PubMed

Vejříková, Ivana; Eloranta, Antti P; Vejřík, Lukáš; Šmejkal, Marek; Čech, Martin; Sajdlová, Zuzana; Frouzová, Jaroslava; Kiljunen, Mikko; Peterka, Jiří

2017-01-01

Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall

Annual variation in the atmospheric radon concentration in Japan.

PubMed

Kobayashi, Yuka; Yasuoka, Yumi; Omori, Yasutaka; Nagahama, Hiroyuki; Sanada, Tetsuya; Muto, Jun; Suzuki, Toshiyuki; Homma, Yoshimi; Ihara, Hayato; Kubota, Kazuhito; Mukai, Takahiro

2015-08-01

Anomalous atmospheric variations in radon related to earthquakes have been observed in hourly exhaust-monitoring data from radioisotope institutes in Japan. The extraction of seismic anomalous radon variations would be greatly aided by understanding the normal pattern of variation in radon concentrations. Using atmospheric daily minimum radon concentration data from five sampling sites, we show that a sinusoidal regression curve can be fitted to the data. In addition, we identify areas where the atmospheric radon variation is significantly affected by the variation in atmospheric turbulence and the onshore-offshore pattern of Asian monsoons. Furthermore, by comparing the sinusoidal regression curve for the normal annual (seasonal) variations at the five sites to the sinusoidal regression curve for a previously published dataset of radon values at the five Japanese prefectures, we can estimate the normal annual variation pattern. By fitting sinusoidal regression curves to the previously published dataset containing sites in all Japanese prefectures, we find that 72% of the Japanese prefectures satisfy the requirements of the sinusoidal regression curve pattern. Using the normal annual variation pattern of atmospheric daily minimum radon concentration data, these prefectures are suitable areas for obtaining anomalous radon variations related to earthquakes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Tectonic activity as a significant source of crustal tetrafluoromethane emissions to the atmosphere: observations in groundwaters along the San Andreas Fault

USGS Publications Warehouse

Deeds, Daniel A.; Kulongoski, Justin T.; Muhle, Jens; Weiss, Ray F.

2015-01-01

Tetrafluoromethane (CF4) concentrations were measured in 14 groundwater samples from the Cuyama Valley, Mil Potrero and Cuddy Valley aquifers along the Big Bend section of the San Andreas Fault System (SAFS) in California to assess whether tectonic activity in this region is a significant source of crustal CF4 to the atmosphere. Dissolved CF4 concentrations in all groundwater samples but one were elevated with respect to estimated recharge concentrations including entrainment of excess air during recharge (CreCre; ∼30 fmol kg−1 H2O), indicating subsurface addition of CF4 to these groundwaters. Groundwaters in the Cuyama Valley contain small CF4 excesses (0.1–9 times CreCre), which may be attributed to an in situ release from weathering and a minor addition of deep crustal CF4 introduced to the shallow groundwater through nearby faults. CF4 excesses in groundwaters within 200 m of the SAFS are larger (10–980 times CreCre) and indicate the presence of a deep crustal flux of CF4 that is likely associated with the physical alteration of silicate minerals in the shear zone of the SAFS. Extrapolating CF4 flux rates observed in this study to the full extent of the SAFS (1300 km × 20–100 km) suggests that the SAFS potentially emits (0.3–1)×10−1 kg(0.3–1)×10−1 kg CF4 yr−1 to the Earth's surface. For comparison, the chemical weathering of ∼7.5×104 km2∼7.5×104 km2 of granitic rock in California is estimated to release (0.019–3.2)×10−1 kg(0.019–3.2)×10−1 kg CF4 yr−1. Tectonic activity is likely an important, and potentially the dominant, driver of natural emissions of CF4 to the atmosphere. Variations in preindustrial atmospheric CF4 as observed in paleo-archives such as ice cores may therefore represent changes in both continental weathering and tectonic activity, including changes driven by variations in continental ice cover during glacial–interglacial transitions.

Variations of High-Latitude Geomagnetic Pulsation Frequencies: A Comparison of Time-of-Flight Estimates and IMAGE Magnetometer Observations

NASA Astrophysics Data System (ADS)

Sandhu, J. K.; Yeoman, T. K.; James, M. K.; Rae, I. J.; Fear, R. C.

2018-01-01

The fundamental eigenfrequencies of standing Alfvén waves on closed geomagnetic field lines are estimated for the region spanning 5.9≤L < 9.5 over all MLT (Magnetic Local Time). The T96 magnetic field model and a realistic empirical plasma mass density model are employed using the time-of-flight approximation, refining previous calculations that assumed a relatively simplistic mass density model. An assessment of the implications of using different mass density models in the time-of-flight calculations is presented. The calculated frequencies exhibit dependences on field line footprint magnetic latitude and MLT, which are attributed to both magnetic field configuration and spatial variations in mass density. In order to assess the validity of the time-of-flight calculated frequencies, the estimates are compared to observations of FLR (Field Line Resonance) frequencies. Using IMAGE (International Monitor for Auroral Geomagnetic Effects) ground magnetometer observations obtained between 2001 and 2012, an automated FLR identification method is developed, based on the cross-phase technique. The average FLR frequency is determined, including variations with footprint latitude and MLT, and compared to the time-of-flight analysis. The results show agreement in the latitudinal and local time dependences. Furthermore, with the use of the realistic mass density model in the time-of-flight calculations, closer agreement with the observed FLR frequencies is obtained. The study is limited by the latitudinal coverage of the IMAGE magnetometer array, and future work will aim to extend the ground magnetometer data used to include additional magnetometer arrays.

Long-time observation of annual variation of Taiwan Strait upwelling in summer season

NASA Astrophysics Data System (ADS)

Tang, D. L.; Kawamura, H.; Guan, L.

The Taiwan Strait is between Taiwan Island and Mainland China, where several upwelling zones are well known for good fishing grounds. Earlier studies in the strait have been conducted on detecting upwelling by ship measurements with short-term cruises, but long-term variations of upwelling in this region are not understood. The present paper examines satellite images for a long-time observation of two major upwelling zones in the Taiwan Strait: Taiwan Bank Upwelling (TBU) and Dongshan Upwelling (DSU). Sea surface temperature (SST) and chlorophyll a (Chl-a) images have been analyzed for summer months (June, July, and August) from 1980 to 2002. Results reveal annual variation of two upwelling zones. These two upwelling zones occur every year characterized with distinct low water temperature and high Chl-a concentrations. During the period from 1989 to 1998, SST is found to be 1.15 °C lower in TBU, and 1.42 °C lower in the DSU than the Taiwan Strait. The size of DSU has been found to be larger during summer of 1989, 1990, 1993 and 1995; TBU has been found to be weak during summer of 1994 and 1997. Ocean color images obtained from CZCS, OCI, and SeaWiFS also show high Chl-a concentrations (0.8-2.5 mg m-3) in two upwelling zones, which coincide with low SST in terms of location, shape, and time. These high Chl-a concentrations in TBU and DSU may be related to upwelling waters that bring nutrients from bottom to surface. The present results also show the potential of using satellite data for monitoring of ocean environment for long time period.

Spectral irradiance variations: comparison between observations and the SATIRE model on solar rotation time scales

NASA Astrophysics Data System (ADS)

Unruh, Y. C.; Krivova, N. A.; Solanki, S. K.; Harder, J. W.; Kopp, G.

2008-07-01

Aims: We test the reliability of the observed and calculated spectral irradiance variations between 200 and 1600 nm over a time span of three solar rotations in 2004. Methods: We compare our model calculations to spectral irradiance observations taken with SORCE/SIM, SoHO/VIRGO, and UARS/SUSIM. The calculations assume LTE and are based on the SATIRE (Spectral And Total Irradiance REconstruction) model. We analyse the variability as a function of wavelength and present time series in a number of selected wavelength regions covering the UV to the NIR. We also show the facular and spot contributions to the total calculated variability. Results: In most wavelength regions, the variability agrees well between all sets of observations and the model calculations. The model does particularly well between 400 and 1300 nm, but fails below 220 nm, as well as for some of the strong NUV lines. Our calculations clearly show the shift from faculae-dominated variability in the NUV to spot-dominated variability above approximately 400 nm. We also discuss some of the remaining problems, such as the low sensitivity of SUSIM and SORCE for wavelengths between approximately 310 and 350 nm, where currently the model calculations still provide the best estimates of solar variability.

The National Emissions Inventory Significantly Overestimates NOx Emissions: Analysis of CMAQ and in situ observations from DISCOVER-AQ

NASA Astrophysics Data System (ADS)

Anderson, D. C.; Dickerson, R. R.; Loughner, C.

2013-12-01

NOx and CO not only adversely impact human health, but they, along with associated VOCs, are also important precursors for O3 formation. While ambient NOx and CO concentrations have decreased dramatically over the past 10-20 years, O3 has remained a more recalcitrant problem, particularly in the Baltimore/Washington region. Reduction of O3 production requires that emissions inventories, such as the National Emissions Inventory (NEI), accurately capture total emissions of CO and NOx while also correctly apportioning them among different sectors. Previous evaluations of the NEI paint different pictures of its accuracy, with assertions that it overestimates either one or both of CO and NOx from anywhere between 25 percent to a factor of 2. These conflicting claims warrant further investigation. In this study, measurements of NOx and CO taken aboard the NOAA P3B airplane during the 2011 DISCOVER-AQ field campaign were used to determine the NOx/CO emissions ratio at 6 locations in the Washington/Baltimore region. An average molar emissions ratio of 12.8 × 1.2 CO/NOx was found by calculating the change in CO over the change in NOx from vertical concentration profiles in the planetary boundary layer. Ratios showed little variation with location. Observed values were approximately a factor of 1.35 - 1.75 times greater than that predicted by the annual, countywide emissions ratio from the 2008 NEI. When compared to a temporalized, gridded version of the inventory processed by SMOKE, ratio observations were greater than that predicted by inventories by up to a factor of 2. Comparison of the in situ measurements and remotely sensed observations from MOPITT of CO to the Community Multiscale Air Quality (CMAQ) model agree within 10-35 percent, with the model higher on average. Measurements of NOy by two separate analytical techniques, on the other hand, show that CMAQ consistently and significantly overestimates NOy concentrations. Combined with the CO observations, this

Observations of Academic Instruction for Students with Significant Intellectual Disability: Three States, Thirty-Nine Classrooms, One View

ERIC Educational Resources Information Center

Restorff, Diane E.; Abery, Brian H.

2013-01-01

As part of the validation process for alternate assessments, 39 classroom observations were conducted to gather data about current practices in providing academic instruction to students with significant intellectual disability. Using a standardized protocol, data were gathered using direct instructional observation, an Individualized Education…

Spatial and temporal variations of aridity indices in Iraq

NASA Astrophysics Data System (ADS)

Şarlak, Nermin; Mahmood Agha, Omar M. A.

2017-06-01

This study investigates the spatial and temporal variations of the aridity indices to reveal the desertification vulnerability of Iraq region. Relying on temperature and precipitation data taken from 28 meteorological stations for 31 years, the study aims to determine (1) dry land types and their delineating boundaries and (2) temporal change in aridity conditions in Iraq. Lang's aridity (Im), De Martonne's aridity (Am), United Nations Environmental Program (UNEP) aridity (AIu), and Erinç aridity (IE) indices were selected in this study because of the scarcity of the observed data. The analysis of the spatial variation of aridity indices exhibited that the arid and semi-arid regions cover about 97% of the country's areas. As for temporal variations, it was observed that the aridity indices tend to decrease (statistically significant or not) for all stations. The cumulative sum charts (CUSUMs) were applied to detect the year on which the climate pattern of aridity indices had changed from one pattern to another. The abrupt change point was detected around year 1997 for the majority of the stations. Thus, the spatial and temporal aridity characteristics in Iraq were examined for the two periods 1980-1997 and 1998-2011 (before and after the change-point year) to observe the influence of abrupt change point on aridity phenomena. The spatial variation after 1997 was observed from semi-arid (dry sub humid) to arid (semi-arid) especially at the stations located in northern Iraq, while hyper-arid and arid climatic conditions were still dominant over southern and central Iraq. Besides, the negative temporal variations of the two periods 1980-1997 and 1998-2011 were obtained for almost every station. As a result, it was emphasized that Iraq region, like other Middle East regions, has become drier after 1997. The observed reduction in precipitation and increase in temperature for this region seem to make the situation worse in future.

Cultivar Variation in Hormonal Balance Is a Significant Determinant of Disease Susceptibility to Xanthomonas campestris pv. campestris in Brassica napus.

PubMed

Islam, Md Tabibul; Lee, Bok-Rye; Park, Sang-Hyun; La, Van Hien; Bae, Dong-Won; Kim, Tae-Hwan

2017-01-01

This study aimed to directly elucidate cultivar variation in disease susceptibility and disease responses in relation to hormonal status in the interaction of Brassica napus cultivars and Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot disease. Fully expanded leaves of six B. napus cultivars (cvs. Capitol, Youngsan, Saturnin, Colosse, Tamra, and Mosa) were inoculated with Xcc. At 14 days post-inoculation with Xcc, cultivar variation in susceptibility or resistance was interpreted with defense responses as estimated by redox status, defensive metabolites, and expression of phenylpropanoid synthesis-related genes in relation to endogenous hormonal status. Disease susceptibility of six cultivars was distinguished by necrotic lesions in the Xcc-inoculated leaves and characterized concurrently based on the higher increase in reactive oxygen species and lipid peroxidation. Among these cultivars, as the susceptibility was higher, the ratios of abscisic acid (ABA)/jasmonic acid (JA) and salicylic acid (SA)/JA tended to increase with enhanced expression of SA signaling regulatory gene NPR1 and transcriptional factor TGA1 and antagonistic suppression of JA-regulated gene PDF 1.2 . In the resistant cultivar (cv. Capitol), accumulation of defensive metabolites with enhanced expression of genes involved in flavonoids (chalcone synthase), proanthocyanidins (anthocyanidin reductase), and hydroxycinnamic acids (ferulate-5-hydroxylase) biosynthesis and higher redox status were observed, whereas the opposite results were obtained for susceptible cultivars (cvs. Mosa and Tamra). These results clearly indicate that cultivar variation in susceptibility to infection by Xcc was determined by enhanced alteration of the SA/JA ratio, as a negative regulator of redox status and phenylpropanoid synthesis in the Brasica napus -Xcc pathosystem.

Genome-wide recombination dynamics are associated with phenotypic variation in maize.

PubMed

Pan, Qingchun; Li, Lin; Yang, Xiaohong; Tong, Hao; Xu, Shutu; Li, Zhigang; Li, Weiya; Muehlbauer, Gary J; Li, Jiansheng; Yan, Jianbing

2016-05-01

Meiotic recombination is a major driver of genetic diversity, species evolution, and agricultural improvement. Thus, an understanding of the genetic recombination landscape across the maize (Zea mays) genome will provide insight and tools for further study of maize evolution and improvement. Here, we used c. 50 000 single nucleotide polymorphisms to precisely map recombination events in 12 artificial maize segregating populations. We observed substantial variation in the recombination frequency and distribution along the ten maize chromosomes among the 12 populations and identified 143 recombination hot regions. Recombination breakpoints were partitioned into intragenic and intergenic events. Interestingly, an increase in the number of genes containing recombination events was accompanied by a decrease in the number of recombination events per gene. This kept the overall number of intragenic recombination events nearly invariable in a given population, suggesting that the recombination variation observed among populations was largely attributed to intergenic recombination. However, significant associations between intragenic recombination events and variation in gene expression and agronomic traits were observed, suggesting potential roles for intragenic recombination in plant phenotypic diversity. Our results provide a comprehensive view of the maize recombination landscape, and show an association between recombination, gene expression and phenotypic variation, which may enhance crop genetic improvement. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Seasonal and Geographical Variation of Dengue Vectors in Narathiwat, South Thailand

PubMed Central

Boonklong, Ornanong; Bhumiratana, Adisak

2016-01-01

Using GIS-based land use map for the urban-rural division (the relative ratio of population density adjusted to relatively Aedes-infested land area), we demonstrated significant independent observations of seasonal and geographical variation of Aedes aegypti and Aedes albopictus vectors between Muang Narathiwat district (urban setting) and neighbor districts (rural setting) of Narathiwat, Southern Thailand, based on binomial distribution of Aedes vectors in water-holding containers (water storage containers, discarded receptacles, miscellaneous containers, and natural containers). The distribution of Aedes vectors was influenced seasonally by breeding outdoors rather than indoors in all 4 containers. Accordingly, both urban and rural settings elicited significantly seasonal (wet versus dry) distributions of Ae. aegypti larvae observed in water storage containers (P = 0.001 and P = 0.002) and natural containers (P = 0.016 and P = 0.015), whereas, in rural setting, the significant difference was observed in discarded receptacles (P = 0.028) and miscellaneous containers (P < 0.001). Seasonal distribution of Ae. albopictus larvae in any containers in urban setting was not remarkably noticed, whereas, in rural setting, the significant difference was observed in water storage containers (P = 0.007) and discarded receptacles (P < 0.001). Moreover, the distributions of percentages of container index for Aedes-infested households in dry season were significantly lower than that in other wet seasons, P = 0.034 for urban setting and P = 0.001 for rural setting. Findings suggest that seasonal and geographical variation of Aedes vectors affect the infestation in those containers in human inhabitations and surroundings. PMID:27437001

Seasonal Variations of the James Webb Space Telescope Orbital Dynamics

NASA Technical Reports Server (NTRS)

Brown, Jonathan; Peterson, Jeremy; Villac, Benjamin; Yu, Wayne

2015-01-01

LV separation state is fixed ECEF, so inertial states vary with hourly, daily, monthly, and yearly frequencies The net effect of all frequencies leads to significant variations in orbit geometry Injection states can be matched with invariant manifolds of periodic orbits in the CR3BP to explain observed final orbit.

Significance levels for studies with correlated test statistics.

PubMed

Shi, Jianxin; Levinson, Douglas F; Whittemore, Alice S

2008-07-01

When testing large numbers of null hypotheses, one needs to assess the evidence against the global null hypothesis that none of the hypotheses is false. Such evidence typically is based on the test statistic of the largest magnitude, whose statistical significance is evaluated by permuting the sample units to simulate its null distribution. Efron (2007) has noted that correlation among the test statistics can induce substantial interstudy variation in the shapes of their histograms, which may cause misleading tail counts. Here, we show that permutation-based estimates of the overall significance level also can be misleading when the test statistics are correlated. We propose that such estimates be conditioned on a simple measure of the spread of the observed histogram, and we provide a method for obtaining conditional significance levels. We justify this conditioning using the conditionality principle described by Cox and Hinkley (1974). Application of the method to gene expression data illustrates the circumstances when conditional significance levels are needed.

GNSS Observations of Ionospheric Variations During the 21 August 2017 Solar Eclipse

NASA Astrophysics Data System (ADS)

Coster, Anthea J.; Goncharenko, Larisa; Zhang, Shun-Rong; Erickson, Philip J.; Rideout, William; Vierinen, Juha

2017-12-01

On 21 August 2017, during daytime hours, a total solar eclipse with a narrow ˜160 km wide umbral shadow occurred across the continental United States. Totality was observed from the Oregon coast at ˜9:15 local standard time (LST) (17:20 UT) to the South Carolina coast at ˜13:27 LST (18:47 UT). A dense network of Global Navigation Satellite Systems (GNSS) receivers was utilized to produce total electron content (TEC) and differential TEC. These data were analyzed for the latitudinal and longitudinal response of the TEC and for the presence of traveling ionospheric disturbances (TIDs) during eclipse passage. A significant TEC depletion, in some cases greater than 60%, was observed associated with the eclipse shadow, exceeding initial model predictions of 35%. Evidence of enhanced large-scale TID activity was detected over the United States prior to and following the large TEC depletion observed near the time of totality. Signatures of enhanced TEC structures were observed over the Rocky Mountain chain during the main period of TEC depletion.

Variation in Physician Practice Styles within and across Emergency Departments

PubMed Central

Van Parys, Jessica

2016-01-01

Despite the significant responsibility that physicians have in healthcare delivery, we know surprisingly little about why physician practice styles vary within or across institutions. Estimating variation in physician practice styles is complicated by the fact that patients are rarely randomly assigned to physicians. This paper uses the quasi-random assignment of patients to physicians in emergency departments (EDs) to show how physicians vary in their treatment of patients with minor injuries. The results reveal a considerable degree of variation in practice styles within EDs; physicians at the 75th percentile of the spending distribution spend 20% more than physicians at the 25th percentile. Observable physician characteristics do not explain much of the variation across physicians, but there is a significant degree of sorting between physicians and EDs over time, with high-cost physicians sorting into high-cost EDs as they gain experience. The results may shed light on why some EDs remain persistently higher-cost than others. PMID:27517464

Variation of saturation effect in the ionospheric F2 critical frequency at low latitude

NASA Astrophysics Data System (ADS)

Ikubanni, S. O.; Adeniyi, J. O.

2013-08-01

Saturation in the dependence of foF2 on solar flux is a phenomenon more pronounced in the equatorial ionization anomaly region. The phenomenon was observed in the relationship between the F2 critical frequency (foF2) and any solar indices. Using a two-segmented regression fit on data from an African low latitude station (Geographical Latitude 12.4°N; Geomagnetic latitude 3.5°N), saturation features from the dependence of foF2 on solar radio flux (F10.7) was studied. Diurnal and seasonal variation were studied for the first time in this low latitude region of the African sector. Significant variations were observed, especially in the solstices. It was observed that saturation effect is closely related to the hourly F2 critical frequency and these results were compared with those from Asian, Australian and the American sectors. The diurnal and seasonal variations find their explanations in the photo-ionization process, the fountain effect, and the pre-reversal enhancement while the seasonal variation was attributed to both the ion drift and thermospheric circulation. Future work with larger volume of data is expected to validate the observations from this study.

Regional deep hyperthermia: impact of observer variability in CT-based manual tissue segmentation on simulated temperature distribution

NASA Astrophysics Data System (ADS)

Aklan, Bassim; Hartmann, Josefin; Zink, Diana; Siavooshhaghighi, Hadi; Merten, Ricarda; Putz, Florian; Ott, Oliver; Fietkau, Rainer; Bert, Christoph

2017-06-01

The aim of this study was to systematically investigate the influence of the inter- and intra-observer segmentation variation of tumors and organs at risk on the simulated temperature coverage of the target. CT scans of six patients with tumors in the pelvic region acquired for radiotherapy treatment planning were used for hyperthermia treatment planning. To study the effect of inter-observer variation, three observers manually segmented in the CT images of each patient the following structures: fat, muscle, bone and the bladder. The gross tumor volumes (GTV) were contoured by three radiation oncology residents and used as the hyperthermia target volumes. For intra-observer variation, one of the observers of each group contoured the structures of each patient three times with a time span of one week between the segmentations. Moreover, the impact of segmentation variations in organs at risk (OARs) between the three inter-observers was investigated on simulated temperature distributions using only one GTV. The spatial overlap between individual segmentations was assessed by the Dice similarity coefficient (DSC) and the mean surface distance (MSD). Additionally, the temperatures T90/T10 delivered to 90%/10% of the GTV, respectively, were assessed for each observer combination. The results of the segmentation similarity evaluation showed that the DSC of the inter-observer variation of fat, muscle, the bladder, bone and the target was 0.68  ±  0.12, 0.88  ±  0.05, 0.73  ±  0.14, 0.91  ±  0.04 and 0.64  ±  0.11, respectively. Similar results were found for the intra-observer variation. The MSD results were similar to the DSCs for both observer variations. A statistically significant difference (p  <  0.05) was found for T90 and T10 in the predicted target temperature due to the observer variability. The conclusion is that intra- and inter-observer variations have a significant impact on the temperature coverage of the

Secular variation and fluctuation of GPS Total Electron Content over Antarctica

NASA Astrophysics Data System (ADS)

Jin, Rui; Jin, Shuanggen

2013-01-01

The total electron content (TEC) is an important parameters in the Earth's ionosphere, related to various space weather and solar activities. However, understanding of the complex ionospheric environments is still a challenge due to the lack of direct observations, particularly in the polar areas, e.g., Antarctica. Now the Global Positioning System (GPS) can be used to retrieve total electron content (TEC) from dual-frequency observations. The continuous GPS observations in Antarctica provide a good opportunity to investigate ionospheric climatology. In this paper, the long-term variations and fluctuations of TEC over Antarctica are investigated from CODE global ionospheric maps (GIM) with a resolution of 2.5°×5° every two hours since 1998. The analysis shows significant seasonal and secular variations in the GPS TEC. Furthermore, the effects of TEC fluctuations are discussed.

Weather explains high annual variation in butterfly dispersal

PubMed Central

Rytteri, Susu; Heikkinen, Risto K.; Heliölä, Janne; von Bagh, Peter

2016-01-01

Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark–release–recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79–91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming. PMID:27440662

Weather explains high annual variation in butterfly dispersal.

PubMed

Kuussaari, Mikko; Rytteri, Susu; Heikkinen, Risto K; Heliölä, Janne; von Bagh, Peter

2016-07-27

Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark-release-recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79-91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming. © 2016 The Author(s).

Genetic variation in steelhead of Oregon and northern California

USGS Publications Warehouse

Reisenbichler, R.R.; McIntyre, J.D.; Solazzi, M.F.; Landino, S.W

1992-01-01

Steelhead Oncorhynchus mykiss from various sites between the Columbia River and the Mad River, California, were genetically characterized at 10 protein-coding loci or pairs of loci by starch gel electrophoresis. Fish from coastal streams differed from fish east of the Cascade Mountains and from fish of the Willamette River (a tributary of the Columbia River, west of the Cascade Mountains). Coastal steelhead from the northern part of the study area differed from those in the southern part. Genetic differentiation within and among drainages was not statistically significant; however, gene diversity analysis and the life history of steelhead suggested that fish from different drainages should be considered as separate populations. Genetic variation among fish in separate drainages was similar to that reported in northwestern Washington and less than that reported in British Columbia. Allele frequencies varied significantly among year-classes. Genetic variation within samples accounted for 98.3% of the total genetic variation observed in this study. Most hatchery populations differed from wild populations, suggesting that conservation of genetic diversity among and within wild populations could be facilitated by altering hatchery programs.

Explanation of observable secular variations of gravity and alternative methods of determination of drift of the center of mass of the Earth

NASA Astrophysics Data System (ADS)

Barkin, Yury

2010-05-01

conditionally corresponded to the geocenter of the Earth approximately determined by position of stations of satellite observations, as the center of certain mantle systems of coordinates Oxyz. For an explanation of such significant drift of the center of mass of the Earth the mechanism of the unidirectional displacement of the core of the Earth (and its center of mass) relatively to a viscoelastic mantle [1, 2] has been offered. The next years attempts of determination of velocity of secular drift of the center of mass in the mantle reference frame by methods of a space geodesy on the basis of precision satellite observations were repeatedly undertaken. In our work [3] for determination of a trend of the center of mass the data of the International Service of Rotation of the Earth (IERS) for satellite observations of system DORIS have been used. For components of velocity of drift in geocentric Greenwich system of coordinates for period 1999-2007 estimations have been obtained: on coordinate x) -1.46 mm/yr, y) 0.79 mm/yr and z) 5.29 mm/yr (errors of the specified estimations make 5-10 %). The velocity of trend of the center of mass of the Earth and its direction are characterized by values: 5.54 mm/yr; latitude 72°6 N and a longitude 118°4 E. The direction of displacement of the center of mass will well be coordinated with a direction predicted earlier theoretically [2]: latitude 70° N and a longitude 104° E. We shall emphasize, that observable redistributions of superficial masses of the Earth explain only small part of observable displacement of the center of mass. It testifies in favour of a reality of secular relative displacement of the core and the mantle of the Earth. 2 Secular drift of the core to the North and variations of a gravity on the Earth surface. The displaced core of the Earth is characterized by the large superfluous mass approximately in 16.7 masses of the Moon. The superfluous mass is ditermined by contrast values of average densities of the core and

Major Variations in HIV-1 Capsid Assembly Morphologies Involve Minor Variations in Molecular Structures of Structurally Ordered Protein Segments*

PubMed Central

Lu, Jun-Xia; Bayro, Marvin J.; Tycko, Robert

2016-01-01

We present the results of solid state nuclear magnetic resonance (NMR) experiments on HIV-1 capsid protein (CA) assemblies with three different morphologies, namely wild-type CA (WT-CA) tubes with 35–60 nm diameters, planar sheets formed by the Arg18-Leu mutant (R18L-CA), and R18L-CA spheres with 20–100 nm diameters. The experiments are intended to elucidate molecular structural variations that underlie these variations in CA assembly morphology. We find that multidimensional solid state NMR spectra of 15N,13C-labeled CA assemblies are remarkably similar for the three morphologies, with only small differences in 15N and 13C chemical shifts, no significant differences in NMR line widths, and few differences in the number of detectable NMR cross-peaks. Thus, the pronounced differences in morphology do not involve major differences in the conformations and identities of structurally ordered protein segments. Instead, morphological variations are attributable to variations in conformational distributions within disordered segments, which do not contribute to the solid state NMR spectra. Variations in solid state NMR signals from certain amino acid side chains are also observed, suggesting differences in the intermolecular dimerization interface between curved and planar CA lattices, as well as possible differences in intramolecular helix-helix packing. PMID:27129282

Identification of hydrological model parameter variation using ensemble Kalman filter

NASA Astrophysics Data System (ADS)

Deng, Chao; Liu, Pan; Guo, Shenglian; Li, Zejun; Wang, Dingbao

2016-12-01

Hydrological model parameters play an important role in the ability of model prediction. In a stationary context, parameters of hydrological models are treated as constants; however, model parameters may vary with time under climate change and anthropogenic activities. The technique of ensemble Kalman filter (EnKF) is proposed to identify the temporal variation of parameters for a two-parameter monthly water balance model (TWBM) by assimilating the runoff observations. Through a synthetic experiment, the proposed method is evaluated with time-invariant (i.e., constant) parameters and different types of parameter variations, including trend, abrupt change and periodicity. Various levels of observation uncertainty are designed to examine the performance of the EnKF. The results show that the EnKF can successfully capture the temporal variations of the model parameters. The application to the Wudinghe basin shows that the water storage capacity (SC) of the TWBM model has an apparent increasing trend during the period from 1958 to 2000. The identified temporal variation of SC is explained by land use and land cover changes due to soil and water conservation measures. In contrast, the application to the Tongtianhe basin shows that the estimated SC has no significant variation during the simulation period of 1982-2013, corresponding to the relatively stationary catchment properties. The evapotranspiration parameter (C) has temporal variations while no obvious change patterns exist. The proposed method provides an effective tool for quantifying the temporal variations of the model parameters, thereby improving the accuracy and reliability of model simulations and forecasts.

WE-FG-BRB-01: Clinical Significance of RBE Variations in Proton Therapy

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

Paganetti, H.

2016-06-15

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their

Near-field control and imaging of free charge carrier variations in GaN nanowires

NASA Astrophysics Data System (ADS)

Berweger, Samuel; Blanchard, Paul T.; Brubaker, Matt D.; Coakley, Kevin J.; Sanford, Norman A.; Wallis, Thomas M.; Bertness, Kris A.; Kabos, Pavel

2016-02-01

Despite their uniform crystallinity, the shape and faceting of semiconducting nanowires (NWs) can give rise to variations in structure and associated electronic properties. Here, we develop a hybrid scanning probe-based methodology to investigate local variations in electronic structure across individual n-doped GaN NWs integrated into a transistor device. We perform scanning microwave microscopy (SMM), which we combine with scanning gate microscopy to determine the free-carrier SMM signal contribution and image local charge carrier density variations. In particular, we find significant variations in free carriers across NWs, with a higher carrier density at the wire facets. By increasing the local carrier density through tip-gating, we find that the tip injects current into the NW with strongly localized current when positioned over the wire vertices. These results suggest that the strong variations in electronic properties observed within NWs have significant implications for device design and may lead to new paths to optimization.

The Io plasma torus during the Cassini encounter with Jupiter: Temporal, radial and azimuthal variations

NASA Astrophysics Data System (ADS)

Steffl, Andrew Joseph

During the Cassini spacecraft's flyby of Jupiter (1 October 2000 to 31 March 2001), the Ultraviolet Imaging Spectrograph (UVIS) produced an extensive dataset consisting of several thousand spectrally-dispersed images of the lo plasma torus. The temporal, radial, and azimuthal variability of the to plasma torus during this period are examined. The total EUV power radiated from the torus is found to be ~1.7 x 10 12 W with variations of 25%. Several events were observed during which the torus brightened by 20% over a few hours. Significant changes in the composition of the torus plasma were observed between 1 October 2000 and 11 November 2000. The composition and electron temperature of the torus plasma as a function of radial distance were derived from a scale of the midnight sector of the torus. The radial profile during the Cassini epoch shows significant differences from the Voyager era. The Io torus is found to exhibit significant azimuthal variations in ion composition. This compositional variation is observed to have a period of 10.07 hours 1.5% longer than the System III rotation period of Jupiter. While exhibiting many similar characteristics, the periodicity in the UVIS data is 1.3% shorter than the "System IV" period. The amplitude of the azimuthal variation of S II and S IV varies between 5-25% during the observing period, while the amplitude of the variation of S III and O II remains in the range of 2-5%. The amplitude of the azimuthal compositional asymmetry appears to be modulated by its location in System III longitude. The observed temporal variability is reproduced by models of the torus chemistry that include a factor of 3 increase in the rate of oxygen and sulfur atoms supplied to the extended neutral clouds that are the source of the torus plasma coupled with a ~35% increase in the amount of riot electrons in the Io torus. The observed azimuthal variability of the Io torus is well matched by models incorporating a primary source of hot electrons

Analysis of host genetic diversity and viral entry as sources of between-host variation in viral load

USGS Publications Warehouse

Wargo, Andrew R.; Kell, Alison M.; Scott, Robert J.; Thorgaard, Gary H.; Kurath, Gael

2012-01-01

Little is known about the factors that drive the high levels of between-host variation in pathogen burden that are frequently observed in viral infections. Here, two factors thought to impact viral load variability, host genetic diversity and stochastic processes linked with viral entry into the host, were examined. This work was conducted with the aquatic vertebrate virus, Infectious hematopoietic necrosis virus (IHNV), in its natural host, rainbow trout. It was found that in controlled in vivo infections of IHNV, a suggestive trend of reduced between-fish viral load variation was observed in a clonal population of isogenic trout compared to a genetically diverse population of out-bred trout. However, this trend was not statistically significant for any of the four viral genotypes examined, and high levels of fish-to-fish variation persisted even in the isogenic trout population. A decrease in fish-to-fish viral load variation was also observed in virus injection challenges that bypassed the host entry step, compared to fish exposed to the virus through the natural water-borne immersion route of infection. This trend was significant for three of the four virus genotypes examined and suggests host entry may play a role in viral load variability. However, high levels of viral load variation also remained in the injection challenges. Together, these results indicate that although host genetic diversity and viral entry may play some role in between-fish viral load variation, they are not major factors. Other biological and non-biological parameters that may influence viral load variation are discussed.

Gender variations in the optical properties of skin in murine animal models

NASA Astrophysics Data System (ADS)

Calabro, Katherine; Curtis, Allison; Galarneau, Jean-Rene; Krucker, Thomas; Bigio, Irving J.

2011-01-01

Gender is identified as a significant source of variation in optical reflectance measurements on mouse skin, with variation in the thickness of the dermal layer being the key explanatory variable. For three different mouse strains, the thickness values of the epidermis, dermis, and hypodermis layers, as measured by histology, are correlated to optical reflectance measurements collected with elastic scattering spectroscopy (ESS). In all three strains, males are found to have up to a 50% increase in dermal thickness, resulting in increases of up to 80% in reflectance values and higher observed scattering coefficients, as compared to females. Collagen in the dermis is identified as the primary source of these differences due to its strong scattering nature; increased dermal thickness leads to a greater photon path length through the collagen, as compared to other layers, resulting in a larger scattering signal. A related increase in the observed absorption coefficient in females is also observed. These results emphasize the importance of considering gender during experimental design in studies that involve photon interaction with mouse skin. The results also elucidate the significant impact that relatively small thickness changes can have on observed optical measurements in layered tissue.

Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

NASA Astrophysics Data System (ADS)

Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

2014-12-01

Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

Hubble Space Telescope Observations of Variations in Ganymede's Oxygen Atmosphere and Aurora

NASA Astrophysics Data System (ADS)

Molyneux, P. M.; Nichols, J. D.; Bannister, N. P.; Bunce, E. J.; Clarke, J. T.; Cowley, S. W. H.; Gérard, J.-C.; Grodent, D.; Milan, S. E.; Paty, C.

2018-05-01

We present high-sensitivity Hubble Space Telescope (HST) Cosmic Origins Spectrograph and HST Space Telescope Imaging Spectrograph measurements of atmospheric OI 130.4-nm and OI] 135.6-nm emissions at Ganymede, which exhibit significant spatial and temporal variability. These observations represent the first observations of Ganymede using HST Cosmic Origins Spectrograph and of both the leading and trailing hemispheres within a single HST campaign, minimizing the potential influence of long-term changes in the Jovian plasma sheet or in Ganymede's atmosphere on the comparison of the two hemispheres. The mean disk-averaged OI] 135.6-nm/OI 130.4-nm observed intensity ratio was 2.72 ± 0.57 on the leading hemisphere and 1.42 ± 0.16 on the trailing hemisphere. The observed leading hemisphere ratios are consistent with an O2 atmosphere, but we show that an atomic oxygen component of 10% is required to produce the observed trailing hemisphere ratios. The excess 130.4-nm emission on the trailing hemisphere relative to that expected for an O2 atmosphere was 11 R. The O column density required to produce this excess is determined based on previous estimates of the electron density and temperature at Ganymede and exceeds the limit for an optically thin atmosphere. The implication that the O atmosphere is optically thick may be investigated in future by observing Ganymede as it moves into eclipse or by determining the ratio of the individual components within the 130.4-nm triplet.

Observing the operational significance of discord consumption

NASA Astrophysics Data System (ADS)

Gu, Mile; Chrzanowski, Helen M.; Assad, Syed M.; Symul, Thomas; Modi, Kavan; Ralph, Timothy C.; Vedral, Vlatko; Lam, Ping Koy

2012-09-01

Coherent interactions that generate negligible entanglement can still exhibit unique quantum behaviour. This observation has motivated a search beyond entanglement for a complete description of all quantum correlations. Quantum discord is a promising candidate. Here, we demonstrate that under certain measurement constraints, discord between bipartite systems can be consumed to encode information that can only be accessed by coherent quantum interactions. The inability to access this information by any other means allows us to use discord to directly quantify this `quantum advantage'. We experimentally encode information within the discordant correlations of two separable Gaussian states. The amount of extra information recovered by coherent interaction is quantified and directly linked with the discord consumed during encoding. No entanglement exists at any point of this experiment. Thus we introduce and demonstrate an operational method to use discord as a physical resource.

Small vs. Large Convective Cloud Objects from CERES Aqua Observations: Where are the Intraseasonal Variation Signals?

NASA Technical Reports Server (NTRS)

Xu, Kuan-Man

2016-01-01

During inactive phases of Madden-Julian oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES observations for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In terms of the probability density functions of radiative and cloud physical properties, there are virtually no differences between the MJO phases for the small group, but there are significant differences for the large groups for both DC and CS types. These results suggest that the intreseasonal variation signals reside at the

EXPLORING ANTICORRELATIONS AND LIGHT ELEMENT VARIATIONS IN NORTHERN GLOBULAR CLUSTERS OBSERVED BY THE APOGEE SURVEY

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

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C–N and Mg–Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two mostmore » metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that {sup 28}Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.« less

Exploring Anticorrelations and Light Element Variations in Northern Globular Clusters Observed by the APOGEE Survey

NASA Astrophysics Data System (ADS)

Mészáros, Szabolcs; Martell, Sarah L.; Shetrone, Matthew; Lucatello, Sara; Troup, Nicholas W.; Bovy, Jo; Cunha, Katia; García-Hernández, Domingo A.; Overbeek, Jamie C.; Allende Prieto, Carlos; Beers, Timothy C.; Frinchaboy, Peter M.; García Pérez, Ana E.; Hearty, Fred R.; Holtzman, Jon; Majewski, Steven R.; Nidever, David L.; Schiavon, Ricardo P.; Schneider, Donald P.; Sobeck, Jennifer S.; Smith, Verne V.; Zamora, Olga; Zasowski, Gail

2015-05-01

We investigate the light-element behavior of red giant stars in northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. The intrinsic abundance range relative to measurement errors is examined, and the well-known C-N and Mg-Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two most metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that 28Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.

Diurnal and seasonal variations of gas emissions in the inner coma of comet 67P/Churyumov-Gerasimenko observed with OSIRIS/Rosetta

NASA Astrophysics Data System (ADS)

La Forgia, F.; Lazzarin, M.; Bodewits, D.; A'Hearn, M. F.; Bertini, I.; Penasa, L.; Naletto, G.; Cremonese, G.; Massironi, M.; Ferri, F.; Frattin, E.; Lucchetti, A.; Ferrari, S.; Barbieri, C.

2017-09-01

The gas filters of OSIRIS/Wide Angle Camera (WAC) on board Rosetta spacecraft allowed to study the gaseous emissions of the inner coma of comet 67P/Churyumov-Gerasimenko. OH, NH, CN, NH2 and OI gas species have been monitored between January and September 2015, i.e. from 2.47 AU pre-perihelion, to 1.37 AU post-perihelion, allowing the study of seasonal variations. Each gas sequence covers slightly more than one comet rotation period allowing also the study of diurnal changes. We measured the gas column density between 1 and 3 km from the nucleus limb in the sunward direction. Results will be presented on the gas diurnal light curves and on the long-term variations such as the dependence and correlation with time, heliocentric distance, range, phase angle and sub-solar point. Gas ratios are studied searching for evidence of any compositional change with time and orbital evolution. We searched for connections between particular "active zones" on the nucleus surface. This study will be helpful in connecting ground based observations of 67P with Rosetta in situ observations.

Examining global extreme sea level variations on the coast from in-situ and remote observations

NASA Astrophysics Data System (ADS)

Menendez, Melisa; Benkler, Anna S.

2017-04-01

The estimation of extreme water level values on the coast is a requirement for a wide range of engineering and coastal management applications. In addition, climate variations of extreme sea levels on the coastal area result from a complex interacting of oceanic, atmospheric and terrestrial processes across a wide range of spatial and temporal scales. In this study, variations of extreme sea level return values are investigated from two available sources of information: in-situ tide-gauge records and satellite altimetry data. Long time series of sea level from tide-gauge records are the most valuable observations since they directly measure water level in a specific coastal location. They have however a number of sources of in-homogeneities that may affect the climate description of extremes when this data source is used. Among others, the presence of gaps, historical time in-homogeneities and jumps in the mean sea level signal are factors that can provide uncertainty in the characterization of the extreme sea level behaviour. Moreover, long records from tide-gauges are sparse and there are many coastal areas worldwide without in-situ available information. On the other hand, with the accumulating altimeter records of several satellite missions from the 1990s, approaching 25 recorded years at the time of writing, it is becoming possible the analysis of extreme sea level events from this data source. Aside the well-known issue of altimeter measurements very close to the coast (mainly due to corruption by land, wet troposphere path delay errors and local tide effects on the coastal area), there are other aspects that have to be considered when sea surface height values estimated from satellite are going to be used in a statistical extreme model, such as the use of a multi-mission product to get long observed periods and the selection of the maxima sample, since altimeter observations do not provide values uniform in time and space. Here, we have compared the extreme

Corallite skeletal morphological variation in Hawaiian Porites lobata

NASA Astrophysics Data System (ADS)

Tisthammer, Kaho H.; Richmond, Robert H.

2018-06-01

Due to their high morphological plasticity and complex evolutionary history, the species boundaries of many reef-building corals are poorly understood. The skeletal structures of corals have traditionally been used for species identification, but these structures can be highly variable, and currently we lack knowledge regarding the extent of morphological variation within species. Porites species are notorious for their taxonomic difficulties, both morphologically and genetically, and currently there are several unresolved species complexes in the Pacific. Despite its ubiquitous presence and broad use in coral research, Porites lobata belongs to one such unresolved species complex. To understand the degree of intraspecific variation in skeletal morphology, 120 corallites from the Hawaiian P. lobata were examined. A subset of samples from two genetically differentiated populations from contrasting high- and low-stress environments in Maunalua Bay, Hawaii, were then quantitatively analyzed using multivariate morphometrics. Our observations revealed high intraspecific variation in corallite morphology, as well as significant morphological differences between the two populations of P. lobata. Additionally, significant correlation was found between the morphological and genetic distances calculated from approximately 18,000 loci generated from restriction site-associated DNA sequencing. The unique morphological characters observed from the genetically differentiated population under environmental stress suggest that these characters may have adaptive values, but how such traits relate to fitness and how much plasticity they can exhibit remain to be determined by future studies. Relatively simple morphometric analyses used in our study can be useful in clarifying the existing ambiguity in skeletal architecture, thus contributing to resolving species issues in corals.

Use of cumulative mortality data in patients with acute myocardial infarction for early detection of variation in clinical practice: observational study.

PubMed

Lawrance, R A; Dorsch, M F; Sapsford, R J; Mackintosh, A F; Greenwood, D C; Jackson, B M; Morrell, C; Robinson, M B; Hall, A S

2001-08-11

Use of cumulative mortality adjusted for case mix in patients with acute myocardial infarction for early detection of variation in clinical practice. Observational study. 20 hospitals across the former Yorkshire region. All 2153 consecutive patients with confirmed acute myocardial infarction identified during three months. Variable life-adjusted displays showing cumulative differences between observed and expected mortality of patients; expected mortality calculated from risk model based on admission characteristics of age, heart rate, and systolic blood pressure. The performance of two individual hospitals over three months was examined as an example. One, the smallest district hospital in the region, had a series of 30 consecutive patients but had five more deaths than predicted. The variable life-adjusted display showed minimal variation from that predicted for the first 15 patients followed by a run of unexpectedly high mortality. The second example was the main tertiary referral centre for the region, which admitted 188 consecutive patients. The display showed a period of apparently poor performance followed by substantial improvement, where the plot rose steadily from a cumulative net lives saved of -4 to 7. These variations in patient outcome are unlikely to have been revealed during conventional audit practice. Variable life-adjusted display has been integrated into surgical care as a graphical display of risk-adjusted survival for individual surgeons or centres. In combination with a simple risk model, it may have a role in monitoring performance and outcome in patients with acute myocardial infarction.

Tonic and phasic co-variation of peripheral arousal indices in infants

PubMed Central

Wass, S.V.; de Barbaro, K.; Clackson, K.

2015-01-01

Tonic and phasic differences in peripheral autonomic nervous system (ANS) indicators strongly predict differences in attention and emotion regulation in developmental populations. However, virtually all previous research has been based on individual ANS measures, which poses a variety of conceptual and methodlogical challenges to comparing results across studies. Here we recorded heart rate, electrodermal activity (EDA), pupil size, head movement velocity and peripheral accelerometry concurrently while a cohort of 37 typical 12-month-old infants completed a mixed assessment battery lasting approximately 20 min per participant. We analysed covariation of these autonomic indices in three ways: first, tonic (baseline) arousal; second, co-variation in spontaneous (phasic) changes during testing; third, phasic co-variation relative to an external stimulus event. We found that heart rate, head velocity and peripheral accelerometry showed strong positive co-variation across all three analyses. EDA showed no co-variation in tonic activity levels but did show phasic positive co-variation with other measures, that appeared limited to sections of high but not low general arousal. Tonic pupil size showed significant positive covariation, but phasic pupil changes were inconsistent. We conclude that: (i) there is high covariation between autonomic indices in infants, but that EDA may only be sensitive at extreme arousal levels, (ii) that tonic pupil size covaries with other indices, but does not show predicted patterns of phasic change and (iii) that motor activity appears to be a good proxy measure of ANS activity. The strongest patterns of covariation were observed using epoch durations of 40 s per epoch, although significant covariation between indices was also observed using shorter epochs (1 and 5 s). PMID:26316360

The role of tributary mixing in chemical variations at a karst spring, Milandre, Switzerland

NASA Astrophysics Data System (ADS)

Perrin, J.; Jeannin, P.-Y.; Cornaton, F.

2007-01-01

SummarySolute concentration variations during flood events were investigated in a karst aquifer of the Swiss Jura. Observations were made at the spring, and at the three main subterraneous tributaries feeding the spring. A simple transient flow and transport numerical model was able to reproduce chemographs and hydrographs observed at the spring, as a result of a mixing of the concentration and discharge of the respective tributaries. Sensitivity analysis carried out with the model showed that it is possible to produce chemical variations at the spring even if all tributaries have constant (but different for each of them) solute concentrations. This process is called tributary mixing. The good match between observed and modelled curves indicate that, in the phreatic zone, tributary mixing is probably an important process that shapes spring chemographs. Chemical reactions and other mixing components (e.g. from low permeability volumes) have a limited influence. Dissolution-related (calcium, bicarbonate, specific conductance) and pollution-related parameters (nitrate, chloride, potassium) displayed slightly different behaviours: during moderate flood events, the former showed limited variations compared to the latter. During large flood events, both presented chemographs with significant changes. No significant event water participates in moderate flood events and tributary mixing will be the major process shaping chemographs. Variations are greater for parameters with higher spatial variability (e.g. pollution-related). Whereas for large flood events, the contribution of event water becomes significant and influences the chemographs of all the parameters. As a result, spring water vulnerability to an accidental pollution is low during moderate flood events and under base flow conditions. It strongly increases during large flood events, because event water contributes to the spring discharge.

Temporal variations in the potential hydrological performance of extensive green roof systems

NASA Astrophysics Data System (ADS)

De-Ville, Simon; Menon, Manoj; Stovin, Virginia

2018-03-01

Existing literature provides contradictory information about variation in potential green roof hydrological performance over time. This study has evaluated a long-term hydrological monitoring record from a series of extensive green roof test beds to identify long-term evolutions and sub-annual (seasonal) variations in potential hydrological performance. Monitoring of nine differently-configured extensive green roof test beds took place over a period of 6 years in Sheffield, UK. Long-term evolutions and sub-annual trends in maximum potential retention performance were identified through physical monitoring of substrate field capacity over time. An independent evaluation of temporal variations in detention performance was undertaken through the fitting of reservoir-routing model parameters. Aggregation of the resulting retention and detention variations permitted the prediction of extensive green roof hydrological performance in response to a 1-in-30-year 1-h summer design storm for Sheffield, UK, which facilitated the comparison of multi and sub-annual hydrological performance variations. Sub-annual (seasonal) variation was found to be significantly greater than long-term evolution. Potential retention performance increased by up to 12% after 5-years, whilst the maximum sub-annual variation in potential retention was 27%. For vegetated roof configurations, a 4% long-term improvement was observed for detention performance, compared to a maximum 63% sub-annual variation. Consistent long-term reductions in detention performance were observed in unvegetated roof configurations, with a non-standard expanded-clay substrate experiencing a 45% reduction in peak attenuation over 5-years. Conventional roof configurations exhibit stable long-term hydrological performance, but are nonetheless subject to sub-annual variation.

Gravity Changes and Internal Processes: Some Results Obtained from Observations at Three Volcanoes

NASA Astrophysics Data System (ADS)

Jentzsch, Gerhard; Weise, Adelheid; Rey, Carlos; Gerstenecker, Carl

Temporal gravity changes provide information about mass and/or density variations within and below the volcano edifice. Three active volcanoes have been under investigation; each of them related to a plate boundary: Mayon/Luzon/Philippines, Merapi/Java/Indonesia, and Galeras/Colombia. The observed gravity changes are smaller than previously expected but significant. For the three volcanoes under investigation, and within the observation period, mainly the increase of gravity is observed, ranging from 1,000 nm-2 to 1,600 nms-2. Unexpectedly, the gravity increase is confined to a rather small area with radii of 5 to 8 km around the summit. At Mayon and Merapi the parallel GPS measurements yield no significant elevation changes. This is crucial for the interpretation, as the internal pressure variations do not lead to significant deformation at the surface. Thus the classical Mogi-model for a shallow extending magma reservoir cannot apply. To confine the possible models, the attraction due to changes of groundwater level or soil moisture is estimated along the slope of Merapi exemplarily by 2-D modelling. Mass redistribution or density changes were evaluated within the vent as well as deeper fluid processes to explain the gravity variations; the results are compared to the model incorporating the additional effect of elastic deformation.

Variations of System IV period of the sulfur ions in the Io torus for the volcanic event in 2015 observed by the HISAKI/EXCEED

NASA Astrophysics Data System (ADS)

Ryo, A.; Misawa, H.; Tsuchiya, F.; Kagitani, M.; Yoshioka, K.; Yoshikawa, I.; Kimura, T.; Murakami, G.; Yamazaki, A.

2017-12-01

Previous ground-based and probe observations of Io plasma torus (IPT) in various wavelengths have detected a periodic variation which is longer than System III period (9.925 h). It has been called System IV period. Although various ideas to explain the origin of System IV period are proposed , little progress has been made. A previous study reported that the System IV period was 10.07 h during the Cassini's Jupiter flyby in 2000. This period was shorter than the typical period of 10.21h (Brown 1995). The Io's volcanic event just before Cassini's flyby might shorten the System IV period (Steffl et al., 2006). However, the certainty of this inference is not clear from the Cassini observation. Here, we analyzed time variations in intensities of EUV emissions from IPT obtained by the HISAKI satellite to understand the mechanism responsible for the System IV period and the influence of Io's volcanic event on IPT. The data used in this study was obtained from Dec. 2014 to the middle of May 2015. During this period, the Io's volcanic event from Jan. to Mar. 2015 was reported from the observation of Iogenic sodium emission (Yoneda et al., 2015). To find variations of the System IV period, the temporal variation of System III longitude at peak EUV intensity was derived by fitting light curves of three ion species (S II 76.5 nm + 126 nm, S III 68 nm, and S IV 65.7 nm + 140.5 nm). The System IV periods of S II before and after the Io's volcanic event were 10.16±0.008 h and 10.03±0.006 h, respectively. On the other hands, the System IV period of S II was 9.95±0.003 h during the Io's volcanic event. This is the first observational evidence which shows that the System IV period has shortened during the Io's volcanic event, which is consistent with the result from Cassini observation. Origin of the System IV period has been discussed with sub-corotation of plasma in IPT. Since the sub-corotation occurs due to mass loading of newly picked-up ions into IPT, it is expected that

MR Spectra of Normal Adult Testes and Variations with Age: Preliminary Observations.

PubMed

Tsili, Athina C; Astrakas, Loukas G; Ntorkou, Alexandra; Giannakis, Dimitrios; Stavrou, Sotirios; Maliakas, Vasilios; Sofikitis, Nikolaos; Argyropoulou, Maria I

2016-07-01

The aim was to determine the proton MR (1H-MR) spectra of normal adult testes and variations with age. Forty-one MR spectra of normal testes, including 16 testes from men aged 20-39 years (group I) and 25 testes from men aged 40-69 years (group II), were analyzed. A single-voxel point-resolved spectroscopy sequence (PRESS), with TR/TE: 2000/25 ms was used. The volume of interest was placed to include the majority of normal testicular parenchyma. Association between normalized metabolite concentrations, defined as ratios of the calculated metabolite concentrations relative to creatine concentration, and age was assessed. Quantified metabolites of the spectra were choline (Cho), creatine (Cr), myo-inositol (mI), scyllo-inositol, taurine, lactate, GLx compound, glucose, lipids, and macromolecules resonating at 0.9 ppm (LM09), around 20 ppm (LM20), and at 13 ppm (LM13). Most prominent peaks were Cho, Cr, mI, and lipids. A weak negative correlation between mI and age (P = 0.015) was observed. Higher normalized concentrations of Cho (P = 0.03), mI (P = 0.08), and LM13 (P = 0.05) were found in group I than in group II. 1H-MR spectra of a normal adult testis showed several metabolite peaks. A decrease of levels of Cho, mI, and LM13 was observed with advancing age. • Single-voxel PRESS MRS of a normal testis is feasible. • 1H-MR spectra of a normal testis showed several metabolite peaks. • Most prominent peaks were Cho, Cr, mI, and lipids. • A decrease of Cho, mI, and LM13 was seen with advancing age.

Solar gravitational energy and luminosity variations

NASA Astrophysics Data System (ADS)

Fazel, Z.; Rozelot, J. P.; Lefebvre, S.; Ajabshirizadeh, A.; Pireaux, S.

2008-02-01

Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do so, we use the Total Solar Irradiance (TSI) as an indicator of luminosity. Considering that most of the authors have explained the largest part of the TSI modulation with magnetic network (spots and faculae) but not the whole, we could set constraints on radius and effective temperature variations. Our best fit of modelled to observed irradiance gives d T = 1.2 K at d R = 10 mas. However computations show that the amplitude of solar irradiance modulation is very sensitive to photospheric temperature variations. In order to understand discrepancies between our best fit and recent observations of [Livingston, W.C., Gray, D., Wallace, L., White, O.R., 2005. In: Sankarasubramanian, K., Penn, M., Pevtsov, A. (Eds.), Large-scale Structures and their Role in Solar Activity, ASP Conference Series, vol. 346. Astronomical Society of the Pacific, p. 353], showing no effective surface temperature variation during the solar cycle, we investigated small effective temperature variation in irradiance modeling. We emphasized a phase-shift (correlated or anticorrelated radius and irradiance variations) in the (d R, d T)-parameter plane. We further obtained an upper limit on the amplitude of cyclic solar radius variations between 3.87 and 5.83 km, deduced from the gravitational energy variations. Our estimate is consistent with both observations of the helioseismic radius through the analysis of f-mode frequencies and observations of the basal photospheric temperature at Kitt Peak. Finally, we suggest a mechanism to explain weak changes in the solar shape due to variation of magnetic pressure which modifies the granules size. This mechanism is supported by an estimate of the asphericity-luminosity parameter, w = -7.61 × 10 -3, which implies an

Genome-wide variation in recombination rate in Eucalyptus.

PubMed

Gion, Jean-Marc; Hudson, Corey J; Lesur, Isabelle; Vaillancourt, René E; Potts, Brad M; Freeman, Jules S

2016-08-09

Meiotic recombination is a fundamental evolutionary process. It not only generates diversity, but influences the efficacy of natural selection and genome evolution. There can be significant heterogeneity in recombination rates within and between species, however this variation is not well understood outside of a few model taxa, particularly in forest trees. Eucalypts are forest trees of global economic importance, and dominate many Australian ecosystems. We studied recombination rate in Eucalyptus globulus using genetic linkage maps constructed in 10 unrelated individuals, and markers anchored to the Eucalyptus reference genome. This experimental design provided the replication to study whether recombination rate varied between individuals and chromosomes, and allowed us to study the genomic attributes and population genetic parameters correlated with this variation. Recombination rate varied significantly between individuals (range = 2.71 to 3.51 centimorgans/megabase [cM/Mb]), but was not significantly influenced by sex or cross type (F1 vs. F2). Significant differences in recombination rate between chromosomes were also evident (range = 1.98 to 3.81 cM/Mb), beyond those which were due to variation in chromosome size. Variation in chromosomal recombination rate was significantly correlated with gene density (r = 0.94), GC content (r = 0.90), and the number of tandem duplicated genes (r = -0.72) per chromosome. Notably, chromosome level recombination rate was also negatively correlated with the average genetic diversity across six species from an independent set of samples (r = -0.75). The correlations with genomic attributes are consistent with findings in other taxa, however, the direction of the correlation between diversity and recombination rate is opposite to that commonly observed. We argue this is likely to reflect the interaction of selection and specific genome architecture of Eucalyptus. Interestingly, the differences amongst

Intraspecific Variation among Social Insect Colonies: Persistent Regional and Colony-Level Differences in Fire Ant Foraging Behavior

PubMed Central

Bockoven, Alison A.; Wilder, Shawn M.; Eubanks, Micky D.

2015-01-01

Individuals vary within a species in many ecologically important ways, but the causes and consequences of such variation are often poorly understood. Foraging behavior is among the most profitable and risky activities in which organisms engage and is expected to be under strong selection. Among social insects there is evidence that within-colony variation in traits such as foraging behavior can increase colony fitness, but variation between colonies and the potential consequences of such variation are poorly documented. In this study, we tested natural populations of the red imported fire ant, Solenopsis invicta, for the existence of colony and regional variation in foraging behavior and tested the persistence of this variation over time and across foraging habitats. We also reared single-lineage colonies in standardized environments to explore the contribution of colony lineage. Fire ants from natural populations exhibited significant and persistent colony and regional-level variation in foraging behaviors such as extra-nest activity, exploration, and discovery of and recruitment to resources. Moreover, colony-level variation in extra-nest activity was significantly correlated with colony growth, suggesting that this variation has fitness consequences. Lineage of the colony had a significant effect on extra-nest activity and exploratory activity and explained approximately half of the variation observed in foraging behaviors, suggesting a heritable component to colony-level variation in behavior. PMID:26197456

Decadal variation in Earth's oblateness (J2) from satellite laser ranging data

NASA Astrophysics Data System (ADS)

Cheng, Minkang; Ries, John C.

2018-02-01

For four decades, satellite laser ranging has recorded the global nature of the long-wavelength hydrological mass redistribution within the Earth system, which results in significant variations in the Earth's dynamical oblateness, characterized by the second degree zonal geopotential spherical harmonic J2 (or C20). Analysis of the J2 time-series has shown a significant variation related to the strong El Niño-Southern Oscillation events with periods of 2-6 yr. In particular, the variation related to the powerful 2015-2016 El Niño that peaked during 2015 November-December was one of the strongest on record, comparable with the 1982-1983 and 1997-1998 events. In this study, we investigate further the hydrological mass transfer between atmosphere-ocean-land and their signature in the decadal variations of J2 with timescales of ˜10 yr. We found that the ˜6.4-yr variations can be accounted for by the atmosphere and ocean mass variations based on the improved Atmosphere-Ocean De-aliasing data, and the observed decadal variation in J2 correlates well with the decadal tropical variability characterized by the 5-yr running mean of the El Niño-Southern Oscillation Index, although existing physical models, especially the land water storage, are limited for the purpose of further studies of the excitation.

An hourly variation in zoo visitor interest: measurement and significance for animal welfare research.

PubMed

Davey, Gareth

2006-01-01

A methodological difficulty facing welfare research on nonhuman animals in the zoo is the large number of uncontrolled variables due to variation within and between study sites. Zoo visitors act as uncontrolled variables, with number, density, size, and behavior constantly changing. This is worrisome because previous research linked visitor variables to animal behavioral changes indicative of stress. There are implications for research design: Studies not accounting for visitors' effect on animal welfare risk confounding (visitor) variables distorting their findings. Zoos need methods to measure and minimize effects of visitor behavior and to ensure that there are no hidden variables in research models. This article identifies a previously unreported variable--hourly variation (decrease) in visitor interest--that may impinge on animal welfare and validates a methodology for measuring it. That visitor interest wanes across the course of the day has important implications for animal welfare management; visitor effects on animal welfare are likely to occur, or intensify, during the morning or in earlier visits when visitor interest is greatest. This article discusses this issue and possible solutions to reduce visitor effects on animal well-being.

MAVEN Observations of Solar Wind-Driven Magnetosonic Waves Heating the Martian Dayside Ionosphere

NASA Astrophysics Data System (ADS)

Fowler, C. M.; Andersson, L.; Ergun, R. E.; Harada, Y.; Hara, T.; Collinson, G.; Peterson, W. K.; Espley, J.; Halekas, J.; Mcfadden, J.; Mitchell, D. L.; Mazelle, C.; Benna, M.; Jakosky, B. M.

2018-05-01

We present Mars Atmosphere and Volatile EvolutioN observations of large-amplitude magnetosonic waves propagating through the magnetosheath into the Martian ionosphere near the subsolar point on the dayside of the planet. The observed waves grow in amplitude as predicted for a wave propagating into a denser, charged medium, with wave amplitudes reaching 25 nT, equivalent to ˜40% of the background field strength. These waves drive significant density and temperature variations (˜20% to 100% in amplitude) in the suprathermal electrons and light ion species (H+) that correlate with compressional fronts of the magnetosonic waves. Density and temperature variations are also observed for the ionospheric electrons, and heavy ion species (O+ and O2+); however, these variations are not in phase with the magnetic field variations. Whistler waves are observed at compressional wave fronts and are thought to be produced by unstable, anistropic suprathermal electrons. The magnetosonic waves drive significant ion and electron heating down to just above the exobase region. Ion heating rates are estimated to be between 0.03 and 0.2 eVs-1 per ion, and heavier ions could thus gain escape energy if located in this heating region for ˜10-70 s. The measured ionospheric density profile indicates severe ionospheric erosion above the exobase region, and this is likely caused by substantial ion outflow that is driven by the observed heating. The effectiveness of these magnetosonic waves to energize the plasma close to the exobase could have important implications for the long-term climate evolution for unmagnetized bodies that are exposed to the solar wind.

Salinity Variations of the Intermediate Oyashio Waters and Their Relation with the Lunar Nodal Cycle

NASA Astrophysics Data System (ADS)

Rogachev, K. A.; Shlyk, N. V.

2018-01-01

New oceanographic observations in the period 1990-2015 revealed significant salinity variations in the Oyashio Current. In the last 26 years, the salinity of the upper layer decreased by 0.2 PSU. The most rapid changes in salinity and temperature have been observed in the last five years. The time series of salinity measurements is characterized by the high-amplitude fluctuations synchronized with the lunar nodal cycle (18.6 years); i.e., high salinity is observed in the period of strong tidal currents. Modulation of diurnal tidal currents with the K1 and O1 periods in the lunar nodal cycle is significant [8, 9]. The amplitude was maximal in 1988 and 2006 and minimal in 1997 and 2015. The characteristics of tidal currents in the Oyashio Current and Sea of Okhotsk are considered based on available data of drifting buoys over the Kruzenshtern and Kashevarov banks. The amplitude of salinity variations synchronized with the lunar cycle is approximately 0.1 PSU; therefore, it has made a significant contribution to the salinity decrease in recent years.

Observations of Altitude Dependence and Temporal Variation of ClO in the Venus Mesosphere

NASA Astrophysics Data System (ADS)

Sandor, Brad J.; Clancy, R. Todd

2015-11-01

Analysis of the first observations of ClO in the Venus mesosphere indicate ClO is present above 85 +/-3 km altitude and not below. The retrieved nightside mean abundances show a factor of 2 decrease between observation dates Oct. 23 and Nov. 11, 2015, with change between the two dates evident at more than two sigma confidence. Abundances and altitude distributions are retrieved from submm spectroscopic observations of the 352.88 GHz line of 35ClO (made with the James Clerk Maxwell Telescope - JCMT - located an Mauna Kea, Hawaii).Detection of ClO in the Venus atmosphere confirms a theory put forward by Yung and DeMore (1982) that the Venus atmosphere is stabilized as CO2 due to chlorine catalytic recombination of CO and O. (Without some form of catalysis, the Venus atmosphere would have 10s of percent CO and O2, but it is in fact 97% CO2 and 3% N2, with only trace amounts of CO and O2.) Detailed retrieval of ClO abundances and altitude distributions (the focus of this talk) provides greater insight to the catalytic process, and to other aspects of Venus atmospheric chlorine chemistry. We compare findings of our quantitave retrieval with predictions of photochemical models, and discuss the implications for chlorine photochemisty of the Venus atmosphere. We also discuss retrieved ClO temporal variation with that of upper mesospheric HCl (Sandor and Clancy, 2012).[We acknowledge funding of this project by NASA grants NNX10AB33G, NNX12AI32G, and NNX14AK05G, as well as NSF grant AST-1312985.

Genotypic variation in transpiration efficiency due to differences in photosynthetic capacity among sugarcane-related clones

PubMed Central

Li, Chunjia; Lu, Xin; Xu, Chaohua; Cai, Qing; Basnayake, Jayapathi; Lakshmanan, Prakash; Ghannoum, Oula; Fan, Yuanhong

2017-01-01

Abstract Sugarcane, derived from the hybridization of Saccharum officinarum×Saccharum spontaneum, is a vegetative crop in which the final yield is highly driven by culm biomass production. Cane yield under irrigated or rain-fed conditions could be improved by developing genotypes with leaves that have high intrinsic transpiration efficiency, TEi (CO2 assimilation/stomatal conductance), provided this is not offset by negative impacts from reduced conductance and growth rates. This study was conducted to partition genotypic variation in TEi among a sample of diverse clones from the Chinese collection of sugarcane-related germplasm into that due to variation in stomatal conductance versus that due to variation in photosynthetic capacity. A secondary goal was to define protocols for optimized larger-scale screening of germplasm collections. Genotypic variation in TEi was attributed to significant variation in both stomatal and photosynthetic components. A number of genotypes were found to possess high TEi as a result of high photosynthetic capacity. This trait combination is expected to be of significant breeding value. It was determined that a small number of observations (16) is sufficient for efficiently screening TEi in larger populations of sugarcane genotypes The research methodology and results reported are encouraging in supporting a larger-scale screening and introgression of high transpiration efficiency in sugarcane breeding. However, further research is required to quantify narrow sense heritability as well as the leaf-to-field translational potential of genotypic variation in transpiration efficiency-related traits observed in this study. PMID:28444313

Variation tolerant SoC design

NASA Astrophysics Data System (ADS)

Kozhikkottu, Vivek J.

The scaling of integrated circuits into the nanometer regime has led to variations emerging as a primary concern for designers of integrated circuits. Variations are an inevitable consequence of the semiconductor manufacturing process, and also arise due to the side-effects of operation of integrated circuits (voltage, temperature, and aging). Conventional design approaches, which are based on design corners or worst-case scenarios, leave designers with an undesirable choice between the considerable overheads associated with over-design and significantly reduced manufacturing yield. Techniques for variation-tolerant design at the logic, circuit and layout levels of the design process have been developed and are in commercial use. However, with the incessant increase in variations due to technology scaling and design trends such as near-threshold computing, these techniques are no longer sufficient to contain the effects of variations, and there is a need to address variations at all stages of design. This thesis addresses the problem of variation-tolerant design at the earliest stages of the design process, where the system-level design decisions that are made can have a very significant impact. There are two key aspects to making system-level design variation-aware. First, analysis techniques must be developed to project the impact of variations on system-level metrics such as application performance and energy. Second, variation-tolerant design techniques need to be developed to absorb the residual impact of variations (that cannot be contained through lower-level techniques). In this thesis, we address both these facets by developing robust and scalable variation-aware analysis and variation mitigation techniques at the system level. The first contribution of this thesis is a variation-aware system-level performance analysis framework. We address the key challenge of translating the per-component clock frequency distributions into a system-level application

Annual variations in the Martian bow shock location as observed by the Mars Express mission

NASA Astrophysics Data System (ADS)

Hall, B. E. S.; Lester, M.; Sánchez-Cano, B.; Nichols, J. D.; Andrews, D. J.; Edberg, N. J. T.; Opgenoorth, H. J.; Fränz, M.; Holmström, M.; Ramstad, R.; Witasse, O.; Cartacci, M.; Cicchetti, A.; Noschese, R.; Orosei, R.

2016-11-01

The Martian bow shock distance has previously been shown to be anticorrelated with solar wind dynamic pressure but correlated with solar extreme ultraviolet (EUV) irradiance. Since both of these solar parameters reduce with the square of the distance from the Sun, and Mars' orbit about the Sun increases by ˜0.3 AU from perihelion to aphelion, it is not clear how the bow shock location will respond to variations in these solar parameters, if at all, throughout its orbit. In order to characterize such a response, we use more than 5 Martian years of Mars Express Analyser of Space Plasma and EneRgetic Atoms (ASPERA-3) Electron Spectrometer measurements to automatically identify 11,861 bow shock crossings. We have discovered that the bow shock distance as a function of solar longitude has a minimum of 2.39RM around aphelion and proceeds to a maximum of 2.65RM around perihelion, presenting an overall variation of ˜11% throughout the Martian orbit. We have verified previous findings that the bow shock in southern hemisphere is on average located farther away from Mars than in the northern hemisphere. However, this hemispherical asymmetry is small (total distance variation of ˜2.4%), and the same annual variations occur irrespective of the hemisphere. We have identified that the bow shock location is more sensitive to variations in the solar EUV irradiance than to solar wind dynamic pressure variations. We have proposed possible interaction mechanisms between the solar EUV flux and Martian plasma environment that could explain this annual variation in bow shock location.

Dispersion Measure Variation of Repeating Fast Radio Burst Sources

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

Yang, Yuan-Pei; Zhang, Bing, E-mail: yypspore@gmail.com, E-mail: zhang@physics.unlv.edu

The repeating fast radio burst (FRB) 121102 was recently localized in a dwarf galaxy at a cosmological distance. The dispersion measure (DM) derived for each burst from FRB 121102 so far has not shown significant evolution, even though an apparent increase was recently seen with newly detected VLA bursts. It is expected that more repeating FRB sources may be detected in the future. In this work, we investigate a list of possible astrophysical processes that might cause DM variation of a particular FRB source. The processes include (1) cosmological scale effects such as Hubble expansion and large-scale structure fluctuations; (2)more » FRB local effects such as gas density fluctuation, expansion of a supernova remnant (SNR), a pulsar wind nebula, and an H ii region; and (3) the propagation effect due to plasma lensing. We find that the DM variations contributed by the large-scale structure are extremely small, and any observable DM variation is likely caused by the plasma local to the FRB source. In addition to mechanisms that decrease DM over time, we suggest that an FRB source in an expanding SNR around a nearly neutral ambient medium during the deceleration (Sedov–Taylor and snowplow) phases or in a growing H ii region can increase DM. Some effects (e.g., an FRB source moving in an H ii region or plasma lensing) can produce either positive or negative DM variations. Future observations of DM variations of FRB 121102 and other repeating FRB sources can provide important clues regarding the physical origin of these sources.« less

Anatomical variations of the deep head of Cruveilhier of the flexor pollicis brevis and its significance for the evolution of the precision grip.

PubMed

Dunlap, Samuel S; Aziz, M Ashraf; Ziermann, Janine M

2017-01-01

Cruveilhier described in 1834 the human flexor pollicis brevis (FPB), a muscle of the thenar compartment, as having a superficial and a deep head, respectively, inserted onto the radial and ulnar sesamoids of the thumb. Since then, Cruveilhier's deep head has been controversially discussed. Often this deep head is confused with Henle's "interosseous palmaris volaris" or said to be a slip of the oblique adductor pollicis. In the 1960s, Day and Napier described anatomical variations of the insertions of Cruveilhier's deep head, including its absence, and hypothesized, that the shift of the deep head's insertion from ulnar to radial facilitated "true opposability" in anthropoids. Their general thesis for muscular arrangements underlying the power and precision grip is sound, but they did not delineate their deep head from Henle's muscle or the adductor pollicis, and their description of the attachments of Cruveilhier's deep head were too vague and not supported by a significant portion of the anatomical literature. Here, we reinvestigated Cruveilhier's deep head to resolve the controversy about it and because many newer anatomy textbooks do not describe this muscle, while it is often an obvious functionally (writing, texting, precision grip) and clinically significant thenar muscle. For the first time, we empirically delineated Cruveilhier's deep head from neighboring muscles with which it was previously confused. We observed 100% occurrence of the uncontested deep head in 80 human hands, displaying a similar variability of insertions as Day and Napier, but in significantly different numbers. Furthermore, we found variability in the origin and included as important landmarks the trapezoid and the ligamentum carpi radiatum. We tested the assertion regarding the evolutionary morphology and its role in the improvements in thumb movements during various precision grips. Our overall conclusions differ with respect to the developmental and evolutionary origin of the FPB

Environmental degradation of Opalinus Clay with cyclic variations in relative humidity

NASA Astrophysics Data System (ADS)

Wild, Katrin; Walter, Patric; Madonna, Claudio; Amann, Florian

2016-04-01

Clay shales are considered as favorable host rocks for nuclear waste repositories due to their low permeability, high sorption capacity and the potential for self-sealing. However, the favorable characteristics of the rock mass may change during tunnel excavation. Excavation is accompanied by stress redistribution and the development of an excavation damage zone. Furthermore, unloading and exposure to atmospheric conditions with a lower relative humidity (RH) causes desaturation of the rock mass close to the tunnel. This leads to shrinkage and the formation of desiccation cracks. During the open drift stage, seasonal atmospheric changes, especially RH variations, may alter the rock mass and influence the long-term crack evolution. This contribution discusses the influence of RH variation on the mechanical behavior of OPA. A series of specimens were exposed to short-term and long-term, stepwise cyclic RH variations between about 60 and 95% at constant temperature. Strains were measured using strain gauges to monitor the volumetric response during RH cycles. After each applied RH cycle, Brazilian tensile strength (BTS) tests were performed to identify whether there is a change in tensile strength due to environmental damage caused by the change in RH. Swelling and shrinkage of the specimens accompanied by irreversible volumetric expansion was observed as a consequence of the exposure to RH cycles. However, the irreversible strain was limited to the direction normal to bedding suggesting that internal damage is restricted along the bedding planes. No significant effect of cyclic RH variations on the BTS of the specimens was observed. The strength parallel to bedding remained constant over several cycles while the strength normal to bedding shows a slightly decreasing trend after 2 cycles. Furthermore, the water retention characteristics of the specimens were not altered significantly during stepwise RH cycling as the evolution of the water content was reversible

Statistical Study on Variations of the Ionospheric Ion Density Observed by DEMETER and Related to Seismic Activities

NASA Astrophysics Data System (ADS)

Yan, Rui; Parrot, Michel; Pinçon, Jean-Louis

2017-12-01

In this paper, we present the result of a statistical study performed on the ionospheric ion density variations above areas of seismic activity. The ion density was observed by the low altitude satellite DEMETER between 2004 and 2010. In the statistical analysis a superposed epoch method is used where the observed ionospheric ion density close to the epicenters both in space and in time is compared to background values recorded at the same location and in the same conditions. Data associated with aftershocks have been carefully removed from the database to prevent spurious effects on the statistics. It is shown that, during nighttime, anomalous ionospheric perturbations related to earthquakes with magnitudes larger than 5 are evidenced. At the time of these perturbations the background ion fluctuation departs from a normal distribution. They occur up to 200 km from the epicenters and mainly 5 days before the earthquakes. As expected, an ion density perturbation occurring just after the earthquakes and close to the epicenters is also evidenced.

Observing Storm Surges from Space: A New Opportunity

NASA Astrophysics Data System (ADS)

Han, Guoqi; Ma, Zhimin; Chen, Dake; de Young, Brad; Chen, Nancy

2013-04-01

Coastal tide gauges can be used to monitor variations of a storm surge along the coast, but not in the cross-shelf direction. As a result, the cross-shelf structure of a storm surge has rarely been observed. In this study we focus on Hurricane Igor-induced storm surge off Newfoundland, Canada. Altimetric observations at about 2:30, September 22, 2010 UTC (hours after the passage of Hurricane Igor) reveal prominent cross-shelf variation of sea surface height during the storm passage, including a large nearshore slope and a mid-shelf depression. A significant coastal surge of 1 m derived from satellite altimetry is found to be consistent with tide-gauge measurements at nearby St. John's station. The post-storm sea level variations at St. John's and Argentia are argued to be associated with free equatorward-propagating continental shelf waves (with phase speeds of 11-13 m/s), generated along the northeast Newfoundland coast hours after the storm moved away from St. John's. The cross-shelf e-folding scale of the shelf wave was estimated to be ~100 km. We further show approximate agreement of altimetric and tide-gauge observations in the Gulf of Mexico during Hurricane Katrina (2005) and Isaac (2012). The study for the first time in the literature shows the robustness of satellite altimetry to observe storm surges, complementing tide-gauge observations for the analysis of storm surge characteristics and for the validation and improvement of storm surge models.

Developmental mechanisms underlying variation in craniofacial disease and evolution.

PubMed

Fish, Jennifer L

2016-07-15

Craniofacial disease phenotypes exhibit significant variation in penetrance and severity. Although many genetic contributions to phenotypic variation have been identified, genotype-phenotype correlations remain imprecise. Recent work in evolutionary developmental biology has exposed intriguing developmental mechanisms that potentially explain incongruities in genotype-phenotype relationships. This review focuses on two observations from work in comparative and experimental animal model systems that highlight how development structures variation. First, multiple genetic inputs converge on relatively few developmental processes. Investigation of when and how variation in developmental processes occurs may therefore help predict potential genetic interactions and phenotypic outcomes. Second, genetic mutation is typically associated with an increase in phenotypic variance. Several models outlining developmental mechanisms underlying mutational increases in phenotypic variance are discussed using Satb2-mediated variation in jaw size as an example. These data highlight development as a critical mediator of genotype-phenotype correlations. Future research in evolutionary developmental biology focusing on tissue-level processes may help elucidate the "black box" between genotype and phenotype, potentially leading to novel treatment, earlier diagnoses, and better clinical consultations for individuals affected by craniofacial anomalies. Copyright © 2015 Elsevier Inc. All rights reserved.

Detection of the significant geomagnetic field signals in the interannual variations of Length-of-Day using wavelet method

NASA Astrophysics Data System (ADS)

Liu, Genyou; Duan, Pengshuo; Hao, Xiaoguang; Hu, Xiaogang

2015-04-01

The previous studies indicated that the most of the interannual variations in Length-Of-Day (LOD) could be explained by the joint effects of ENSO (EI Nino-Southern Oscillations) and QBO (Quasi-Biennial Oscillation) phenomenon in the atmosphere. Due to the limit of the used methods, those results cannot give the 'time-frequency' coherence spectrum between ENSO and LOD, and cannot indicate in which specific periods the weak coherence occurred and difficult to give the reliable reason. This paper uses Daubechies wavelet with 10 order vanishing moment to analyze the LOD monthly time series from 1962 to 2011. Based on cross-wavelet and wavelet coherence methods, the analysis of the time-frequency correlations between ENSO and LOD series (1962-2011) on the 1.3~10.7 year scales is given. We have extracted and reconstructed the LOD signals on 1.3~10.7year scales. The result shows that there is obvious weak coherence on both biennial and 5~8 year scales after 1982 relative to before 1982. According to the previous works, the biennial weak coherence is due to QBO, but the weak coherence on 5~8 year scales cannot be interpreted by the effects of ENSO and QBO. In this study, the Geomagnetic field signals (can be characterized as Aa index) are introduced, we have further extracted and reconstructed the LOD, ENSO and Aa signals in 5-8.0 year band using wavelet packet analysis. Through analyzing the standardized series of the three signals, we found a linear time-frequency formula among the original observation series: LOD(t,f) =αENSO(t,f) +βAa(t,f). This study indicates that the LOD signals on 5.3~8.0 year scales can be expressed in term of linear combination of ENSO and Aa signals. Especially after 1982, the contributions of ENSO and Aa to LOD respectively reach about 0.95ms and 1.0ms.The results also imply that there is an obvious Geomagnetic field signal in interannual variations of LOD. Furthermore, after considering the geomagnetic field signal correction, the Pearson

Observed changes of temperature extremes during 1960-2005 in China: natural or human-induced variations?

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Li, Jianfeng; David Chen, Yongqin; Chen, Xiaohong

2011-12-01

The purpose of this study was to statistically examine changes of surface air temperature in time and space and to analyze two factors potentially influencing air temperature changes in China, i.e., urbanization and net solar radiation. Trends within the temperature series were detected by using Mann-Kendall trend test technique. The scientific problem this study expected to address was that what could be the role of human activities in the changes of temperature extremes. Other influencing factors such as net solar radiation were also discussed. The results of this study indicated that: (1) increasing temperature was observed mainly in the northeast and northwest China; (2) different behaviors were identified in the changes of maximum and minimum temperature respectively. Maximum temperature seemed to be more influenced by urbanization, which could be due to increasing urban albedo, aerosol, and air pollutions in the urbanized areas. Minimum temperature was subject to influences of variations of net solar radiation; (3) not significant increasing and even decreasing temperature extremes in the Yangtze River basin and the regions south to the Yangtze River basin could be the consequences of higher relative humidity as a result of increasing precipitation; (4) the entire China was dominated by increasing minimum temperature. Thus, we can say that the warming process of China was reflected mainly by increasing minimum temperature. In addition, consistently increasing temperature was found in the upper reaches of the Yellow River basin, the Yangtze River basin, which have the potential to enhance the melting of permafrost in these areas. This may trigger new ecological problems and raise new challenges for the river basin scale water resource management.

Uranus' and Neptune's Clouds as Revealed by UKIRT/UIST Observations

NASA Astrophysics Data System (ADS)

Irwin, Patrick G. J.; Teanby, N. A.; Davis, G. R.

2009-09-01

In 2006, 2007 and 2008 observations of the near-infrared spectrum of Uranus were made with the UIST instrument of the UK Infrared Telescope, covering the period of Uranus’ Northern Spring Equinox. A significant change in the visible appearance of Uranus occurred during this time with the southern polar zone at 45°S fading, while a corresponding zone at 45°N began to form. In addition the visibility of the equatorial zone increased. The observed spectra were fitted using the NEMESIS optimal estimation retrieval model to determine the variation in the latitudinal and vertical cloud structure during this time. Retrievals were conducted using both the methane absorption coefficients used in our previous analyses and also a newly available revised set of methane coefficients and significant differences were seen, which will be reported. During the Uranus observations in 2007, corresponding observations were also made of Neptune's near-infrared spectrum, albeit with substantially less spatial resolution. The spectra were nevertheless sufficient to retrieve the gross variation in Neptune's latitudinal-vertical cloud structure using both sets of methane absorption coefficients. The retrieved vertical-latitudinal cloud structure on Uranus and Neptune, observed with identical instrument setups, are directly compared and the similarities and differences will be presented and discussed.

Climatic driving forces in inter-annual variation of global FPAR

NASA Astrophysics Data System (ADS)

Peng, Dailiang; Liu, Liangyun; Yang, Xiaohua; Zhou, Bin

2012-09-01

Fraction of Absorbed Photosynthetically Active Radiation (FPAR) characterizes vegetation canopy functioning and its energy absorption capacity. In this paper, we focus on climatic driving forces in inter-annual variation of global FPAR from 1982 to 2006 by Global Historical Climatology Network (GHCN-Monthly) data. Using FPAR-Simple Ratio Vegetation Index (SR) relationship, Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) was used to estimate FPAR at the global scale. The correlation between inter-annual variation of FPAR and temperature, precipitation derived from GHCN-Monthly was examined, during the periods of March-May (MAM), June-August (JJA), September-November (SON), and December-February (DJF) over from 1982 to 2006. The analysis of climatic influence on global FPAR revealed the significant correlation with temperature and precipitation in some meteorological stations area, and a more significant correlation with precipitation was found than which with temperature. Some stations in the regions between 30° N and 60° N and around 30° S in South America, where the annual FPAR variation showed a significant positive correlation with temperature (P < 0.01 or P < 0.05) during MAM, SON, and DJF, as well as in Europe during MAM and SON period. A negative correlation for more stations was observed during JJA. For precipitation, there were many stations showed a significant positive correlation with inter-annual variation of global FPAR (P < 0.01 or P < 0.05), especially for the tropical rainfall forest of Africa and Amazon during the dry season of JJA and SON.

ON THE VARIATION OF SOLAR RADIUS IN ROTATION CYCLES

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

Qu, Z. N.; Kong, D. F.; Xiang, N. B.

2015-01-10

The Date Compensated Discrete Fourier Transform and CLEANest algorithm are used to study the temporal variations of the solar radius observed at Rio de Janeiro Observatory from 1998 March 2 to 2009 November 6. The CLEANest spectra show several significant periodicities around 400, 312, 93.5, 86.2, 79.4, 70.9, 53.2, and 26.3 days. Then, combining the data on the daily solar radius measured at Calern Observatory and Rio de Janeiro Observatory and the corresponding daily sunspot areas, we study the short-term periodicity of the solar radius and the role of magnetic field in the variation of the solar radius. The rotation periodmore » of the daily solar radius is determined to be statistically significant. Moreover, its temporal evolution is anti-phase with that of sunspot activity, and it is found anti-phase with solar activity. Generally, the stronger solar activity is, the more obvious is the anti-phase relation of radius with solar activity. This indicates that strong magnetic fields have a greater inhibitive effect than weak magnetic fields on the variation of the radius.« less

Effect of collaborative care on cost variation in an intensive care unit.

PubMed

Garland, Allan

2013-05-01

Improving the cost-effectiveness of health care requires an understanding of the genesis of health care costs and in particular the sources of cost variation. Little is known about how multiple physicians, caring collaboratively for patients, contribute to costs. To explore the effect of collaborative care by physicians on variation in discretionary costs in an intensive care unit (ICU) by determining the contributions of the attending intensivists and ICU fellows. Prospective, observational study using a multivariable model of median discretionary costs for the first day in the ICU, adjusting for confounding variables. Analysis included 3514 patients who spent more than 2 hours in the ICU on the initial day. Impact of the physicians was assessed via variables representing the specific intensivist and ICU fellow responsible on the first ICU day and allowing for interaction terms. On the initial day, patients spent a median of 10.6 hours (interquartile range, 6.3-16.5) in the ICU, with median discretionary costs of $1343 (interquartile range, $788-2208). There was large variation in adjusted costs attributable to both the intensivists ($359; 95% CI, $244-$474) and the fellows ($756; 95% CI, $550-$965). The interaction terms were not significant (P = .12-.79). In an ICU care model with intensivists and subspecialty fellows, both types of physicians contributed significantly to the observed variation in discretionary costs. However, even in the presence of a hierarchical arrangement of clinical responsibilities, the influences on costs of the 2 types of physicians were independent.

Seasonal variation of wave activities near the mesopause region observed at King Sejong Station (62.22°S, 58.78°W), Antarctica

NASA Astrophysics Data System (ADS)

Lee, Changsup; Kim, Yong Ha; Kim, Jeong-Han; Jee, Geonhwa; Won, Young-In; Wu, Dong L.

2013-12-01

We analyzed the neutral wind data at altitudes of 80-100 km obtained from a VHF meteor radar at King Sejong Station (KSS, 62.22°S, 58.78°W), a key location to study wave activities above the stratospheric vortex near the Antarctic Peninsula. The seasonal behavior of the semidiurnal tides is generally consistent with the prediction of Global Scale Wave Model (GSWM02) except in the altitude region above ~96 km. Gravity wave (GW) activities inferred from the neutral wind variances show a seasonal variation very similar to the semidiurnal tide amplitudes, suggesting a strong interaction between gravity waves and the tide. Despite the consistent seasonal variations of the GW wind variances observed at the adjacent Rothera station, the magnitudes of the wind variance obtained at KSS are much larger than those at Rothera, especially during May-September. The enhanced GW activity at KSS is also observed by Aura Microwave Limb Sounder (MLS) from space in its temperature variance. The observed large wind variances at KSS imply that the Antarctic vortex in the stratosphere may act as an effective filter and source for the GWs in the upper atmosphere.

Decadal-scale variation in dune erosion and accretion rates: An investigation of the significance of changing storm tide frequency and magnitude on the Sefton coast, UK

NASA Astrophysics Data System (ADS)

Pye, K.; Blott, S. J.

2008-12-01

Monitoring of frontal dune erosion and accretion on the Sefton coast in northwest England over the past 50 years has revealed significant spatial and temporal variations. Previous work has shown that the spatial variations primarily reflect longshore differences in beach and nearshore morphology, energy regime and sediment budget, but the causes of temporal variations have not previously been studied in detail. This paper presents the results of work carried out to test the hypothesis that a major cause of temporal variation is changes in the frequency and magnitude of storms, surges and resulting high tides. Dune toe erosion/accretion records dating from 1958 have been compared with tide gauge records at Liverpool and Heysham. Relatively high dune erosion rates at Formby Point 1958-1968 were associated with a relatively large number of storm tides. Slower erosion at Formby, and relatively rapid accretion in areas to the north and south, occurred during the 1970's and 1980's when there were relatively few major storm tides. After 1990 rates of dune erosion at Formby increased again, and dunes to the north and south experienced slower accretion. During this period high storm tides have been more frequent, and the annual number of hours with water levels above the critical level for dune erosion has increased significantly. An increase in the rate of mean sea-level rise at both Liverpool and Heysham is evident since 1990, but we conclude that this factor is of less importance than the occurrence of extreme high tides and wave action associated with storms. The incidence of extreme high tides shows an identifiable relationship with the lunar nodal tidal cycle, but the evidence indicates that meteorological forcing has also had a significant effect. Storms and surges in the eastern Irish Sea are associated with Atlantic depressions whose direction and rate of movement have a strong influence on wind speeds, wave energy and the height of surge tides. However

Seasonal Water Storage Variations as Impacted by Water Abstractions: Comparing the Output of a Global Hydrological Model with GRACE and GPS Observations

NASA Astrophysics Data System (ADS)

Döll, Petra; Fritsche, Mathias; Eicker, Annette; Müller Schmied, Hannes

2014-11-01

Better quantification of continental water storage variations is expected to improve our understanding of water flows, including evapotranspiration, runoff and river discharge as well as human water abstractions. For the first time, total water storage (TWS) on the land area of the globe as computed by the global water model WaterGAP (Water Global Assessment and Prognosis) was compared to both gravity recovery and climate experiment (GRACE) and global positioning system (GPS) observations. The GRACE satellites sense the effect of TWS on the dynamic gravity field of the Earth. GPS reference points are displaced due to crustal deformation caused by time-varying TWS. Unfortunately, the worldwide coverage of the GPS tracking network is irregular, while GRACE provides global coverage albeit with low spatial resolution. Detrended TWS time series were analyzed by determining scaling factors for mean annual amplitude ( f GRACE) and time series of monthly TWS ( f GPS). Both GRACE and GPS indicate that WaterGAP underestimates seasonal variations of TWS on most of the land area of the globe. In addition, seasonal maximum TWS occurs 1 month earlier according to WaterGAP than according to GRACE on most land areas. While WaterGAP TWS is sensitive to the applied climate input data, none of the two data sets result in a clearly better fit to the observations. Due to the low number of GPS sites, GPS observations are less useful for validating global hydrological models than GRACE observations, but they serve to support the validity of GRACE TWS as observational target for hydrological modeling. For unknown reasons, WaterGAP appears to fit better to GPS than to GRACE. Both GPS and GRACE data, however, are rather uncertain due to a number of reasons, in particular in dry regions. It is not possible to benefit from either GPS or GRACE observations to monitor and quantify human water abstractions if only detrended (seasonal) TWS variations are considered. Regarding GRACE, this is

Does the Clock Make the Poison? Circadian Variation in Response to Pesticides

PubMed Central

Hooven, Louisa A.; Sherman, Katherine A.; Butcher, Shawn; Giebultowicz, Jadwiga M.

2009-01-01

Background Circadian clocks govern daily physiological and molecular rhythms, and putative rhythms in expression of xenobiotic metabolizing (XM) genes have been described in both insects and mammals. Such rhythms could have important consequences for outcomes of chemical exposures at different times of day. To determine whether reported XM gene expression rhythms result in functional rhythms, we examined daily profiles of enzyme activity and dose responses to the pesticides propoxur, deltamethrin, fipronil, and malathion. Methodology/Principal Findings Published microarray expression data were examined for temporal patterns. Male Drosophila were collected for ethoxycoumarin-O-deethylase (ECOD), esterase, glutathione-S-transferase (GST), and, and uridine 5′-diphosphoglucosyltransferase (UGT) enzyme activity assays, or subjected to dose-response tests at four hour intervals throughout the day in both light/dark and constant light conditions. Peak expression of several XM genes cluster in late afternoon. Significant diurnal variation was observed in ECOD and UGT enzyme activity, however, no significant daily variation was observed in esterase or GST activity. Daily profiles of susceptibility to lethality after acute exposure to propoxur and fipronil showed significantly increased resistance in midday, while susceptibility to deltamethrin and malathion varied little. In constant light, which interferes with clock function, the daily variation in susceptibility to propoxur and in ECOD and UGT enzyme activity was depressed. Conclusions/Significance Expression and activities of specific XM enzymes fluctuate during the day, and for specific insecticides, the concentration resulting in 50% mortality varies significantly during the day. Time of day of chemical exposure should be an important consideration in experimental design, use of pesticides, and human risk assessment. PMID:19649249

Decadal Variations in Surface Solar Radiation

NASA Astrophysics Data System (ADS)

Wild, M.

2007-05-01

Satellite estimates provide some information on the amount of solar radiation absorbed by the planet back to the 1980s. The amount of solar radiation reaching the Earth surface can be traced further back in time, untill the 1960s at widespread locations and into the first half of the 20th Century at selected sites. These surface sites suggest significant decadal variations in solar radiation incident at the surface, with indication for a widespread dimming from the 1960s up to the mid 1980s, and a recovery thereafter. Indications for changes in surface solar radiation may also be seen in observatinal records of diurnal temperature range, which provide a better global coverage than the radiation measurrements. Trends in diurnal temperature ranges over global land surfaces show, after decades of decline, a distinct tendency to level off since the mid 1980s. This provides further support for a significant shift in surface solar radiation during the 1980s. There is evidence that the changes in surface solar radiation are linked to associated changes in atmospheric aerosol. Variations in scattering sulfur and absorbing black carbon aerosols are in line with the variations in surface solar radiation. This suggests that at least a part of the variations in surface solar radiation should also be seen in the clear sky planetary albedo. Model simulations with a GCM which includes a sophisticated interactive treatment of aerosols and their emission histories (ECHAM5 HAM), can be used to address this issue. The model is shown to be capable of reproducing the reversal from dimming to brightening under cloud-free conditions in many parts of the world, in line with observational evidence. Associated changes can also be seen in the clear sky planetary albedo, albeit of smaller magnitude.

Monitoring interannual variation in global crop yield using long-term AVHRR and MODIS observations

NASA Astrophysics Data System (ADS)

Zhang, Xiaoyang; Zhang, Qingyuan

2016-04-01

Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) data have been extensively applied for crop yield prediction because of their daily temporal resolution and a global coverage. This study investigated global crop yield using daily two band Enhanced Vegetation Index (EVI2) derived from AVHRR (1981-1999) and MODIS (2000-2013) observations at a spatial resolution of 0.05° (∼5 km). Specifically, EVI2 temporal trajectory of crop growth was simulated using a hybrid piecewise logistic model (HPLM) for individual pixels, which was used to detect crop phenological metrics. The derived crop phenology was then applied to calculate crop greenness defined as EVI2 amplitude and EVI2 integration during annual crop growing seasons, which was further aggregated for croplands in each country, respectively. The interannual variations in EVI2 amplitude and EVI2 integration were combined to correlate to the variation in cereal yield from 1982-2012 for individual countries using a stepwise regression model, respectively. The results show that the confidence level of the established regression models was higher than 90% (P value < 0.1) in most countries in the northern hemisphere although it was relatively poor in the southern hemisphere (mainly in Africa). The error in the yield predication was relatively smaller in America, Europe and East Asia than that in Africa. In the 10 countries with largest cereal production across the world, the prediction error was less than 9% during past three decades. This suggests that crop phenology-controlled greenness from coarse resolution satellite data has the capability of predicting national crop yield across the world, which could provide timely and reliable crop information for global agricultural trade and policymakers.

The influence of ENSO, PDO and PNA on secular rainfall variations in Hawai‘i

Treesearch

Abby G. Frazier; Oliver Elison Timm; Thomas W. Giambelluca; Henry F. Diaz

2017-01-01

Over the last century, significant declines in rainfall across the state of Hawai‘i have been observed, and it is unknown whether these declines are due to natural variations in climate, or manifestations of human-induced climate change. Here, a statistical analysis of the observed rainfall variability was applied as first step towards better understanding causes for...

Multi-Decadal Aerosol Variations from 1980 to 2009: A Perspective from Observations and a Global Model

NASA Technical Reports Server (NTRS)

Chin, Mian; Diehl, T.; Tan, Q.; Prospero, J. M.; Kahn, R. A.; Remer, L. A.; Yu, H.; Sayer, A. M.; Bian, H.; Geogdzhayev, I. V.;

Temporal Stability of GPS Transmitter Group Delay Variations.

PubMed

Beer, Susanne; Wanninger, Lambert

2018-05-29

The code observable of global navigation satellite systems (GNSS) is influenced by group delay variations (GDV) of transmitter and receiver antennas. For the Global Positioning System (GPS), the variations can sum up to 1 m in the ionosphere-free linear combination and thus can significantly affect precise code applications. The contribution of the GPS transmitters can amount to 0.8 m peak-to-peak over the entire nadir angle range. To verify the assumption of their time-invariance, we determined daily individual satellite GDV for GPS transmitter antennas over a period of more than two years. Dual-frequency observations of globally distributed reference stations and their multipath combination form the basis for our analysis. The resulting GPS GDV are stable on the level of a few centimeters for C1, P2, and for the ionosphere-free linear combination. Our study reveals that the inconsistencies of the GDV of space vehicle number (SVN) 55 with respect to earlier studies are not caused by temporal instabilities, but are rather related to receiver properties.

Environmental variation between habitats and uptake of heavy metals by Urtica dioica.

PubMed

Otte, M L; Wijte, A H

1993-12-01

The observation from previous surveys, that Urtica dioica plants that had grown in metal contaminated soil in the floodplains of the former Rhine estuary in different habitats, but at comparable total soil metal concentrations, showed significant differences in tissue metal concentrations, led to the hypothesis that variation in other environmental characteristics than soil composition and chemical speciation of metals between habitats is also important in determining uptake and translocation of metals in plants. A field survey indicated that differences in root Cd, Cu and Zn concentrations might partly be explained by variation in speciation of metals in different habitats. However, shoot concentrations showed a different pattern that did not relate to variation in soil metal concentrations. In a habitat experiment Urtica dioica plants were grown in artificially contaminated soil in pots that were placed in the four habitats (grassland, pure reed, mixed reed, osier bed) that were also included in the field survey. After seven weeks the plants showed significant differences in Cu and Zn concentrations in roots and aboveground plant parts and in distribution of the metals in the plants between habitats. It was concluded that variation between habitats in environmental characteristics other than soil composition can explain as much variation in plants as can variation in soil metal concentrations and/or speciation. The implications for assessment of soil metal contamination and uptake by plants are discussed.

Variation and significance of surface heat after the mechanical sand control of Qinghai-Tibet Railway was covered with sandy sediments

NASA Astrophysics Data System (ADS)

Xie, Shengbo; Qu, Jianjun; Mu, Yanhu; Xu, Xiangtian

Mechanical control of drifting sand used to protect the Qinghai-Tibet Railway from sand damage inevitably results in sand deposition, and the change in radiation and heat flux after the ground surface is covered with sandy sediments remains unclear. These variations were studied in this work through field observations along with laboratory analyses and tests. After the ground surface was covered with sandy sediments produced by the mechanical control of sand in the Qinghai-Tibet Railway, the reflectivity increased, and the annual average reflectivity on the surface covered with sandy sediments was higher than that without sandy sediments, with the value increasing by 0.043. Moreover, the surface shortwave radiation increased, whereas the surface net radiation decreased. The annual average value of the surface shortwave radiant flux density on the sandy sediments was higher than that without sandy sediments, with the value increasing by 7.291 W·m-2. The annual average value of the surface net radiant flux density on the sandy sediments decreased by 9.639 W·m-2 compared with that without sandy sediments. The soil heat flux also decreased, and the annual average value of the heat flux in the sandy sediments decreased by 0.375 W·m-2 compared with that without sandy sediments. These variations caused the heat source on the surface of sandy sediments underground to decrease, which is beneficial for preventing permafrost from degradation in the section of sand control of the railway.

Assessment of radiative feedback in climate models using satellite observations of annual flux variation.

PubMed

Tsushima, Yoko; Manabe, Syukuro

2013-05-07

In the climate system, two types of radiative feedback are in operation. The feedback of the first kind involves the radiative damping of the vertically uniform temperature perturbation of the troposphere and Earth's surface that approximately follows the Stefan-Boltzmann law of blackbody radiation. The second kind involves the change in the vertical lapse rate of temperature, water vapor, and clouds in the troposphere and albedo of the Earth's surface. Using satellite observations of the annual variation of the outgoing flux of longwave radiation and that of reflected solar radiation at the top of the atmosphere, this study estimates the so-called "gain factor," which characterizes the strength of radiative feedback of the second kind that operates on the annually varying, global-scale perturbation of temperature at the Earth's surface. The gain factor is computed not only for all sky but also for clear sky. The gain factor of so-called "cloud radiative forcing" is then computed as the difference between the two. The gain factors thus obtained are compared with those obtained from 35 models that were used for the fourth and fifth Intergovernmental Panel on Climate Change assessment. Here, we show that the gain factors obtained from satellite observations of cloud radiative forcing are effective for identifying systematic biases of the feedback processes that control the sensitivity of simulated climate, providing useful information for validating and improving a climate model.

A stepwedge-based method for measuring breast density: observer variability and comparison with human reading

NASA Astrophysics Data System (ADS)

Diffey, Jenny; Berks, Michael; Hufton, Alan; Chung, Camilla; Verow, Rosanne; Morrison, Joanna; Wilson, Mary; Boggis, Caroline; Morris, Julie; Maxwell, Anthony; Astley, Susan

2010-04-01

Breast density is positively linked to the risk of developing breast cancer. We have developed a semi-automated, stepwedge-based method that has been applied to the mammograms of 1,289 women in the UK breast screening programme to measure breast density by volume and area. 116 images were analysed by three independent operators to assess inter-observer variability; 24 of these were analysed on 10 separate occasions by the same operator to determine intra-observer variability. 168 separate images were analysed using the stepwedge method and by two radiologists who independently estimated percentage breast density by area. There was little intra-observer variability in the stepwedge method (average coefficients of variation 3.49% - 5.73%). There were significant differences in the volumes of glandular tissue obtained by the three operators. This was attributed to variations in the operators' definition of the breast edge. For fatty and dense breasts, there was good correlation between breast density assessed by the stepwedge method and the radiologists. This was also observed between radiologists, despite significant inter-observer variation. Based on analysis of thresholds used in the stepwedge method, radiologists' definition of a dense pixel is one in which the percentage of glandular tissue is between 10 and 20% of the total thickness of tissue.

On the Limitations of Variational Bias Correction

NASA Technical Reports Server (NTRS)

Moradi, Isaac; Mccarty, Will; Gelaro, Ronald

2018-01-01

Satellite radiances are the largest dataset assimilated into Numerical Weather Prediction (NWP) models, however the data are subject to errors and uncertainties that need to be accounted for before assimilating into the NWP models. Variational bias correction uses the time series of observation minus background to estimate the observations bias. This technique does not distinguish between the background error, forward operator error, and observations error so that all these errors are summed up together and counted as observation error. We identify some sources of observations errors (e.g., antenna emissivity, non-linearity in the calibration, and antenna pattern) and show the limitations of variational bias corrections on estimating these errors.

Effects of meridional flow variations on solar cycles 23 and 24

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

Upton, Lisa; Hathaway, David H., E-mail: lisa.a.upton@vanderbilt.edu, E-mail: lar0009@uah.edu, E-mail: david.hathaway@nasa.gov

2014-09-10

The faster meridional flow that preceded the solar cycle 23/24 minimum is thought to have led to weaker polar field strengths, producing the extended solar minimum and the unusually weak cycle 24. To determine the impact of meridional flow variations on the sunspot cycle, we have simulated the Sun's surface magnetic field evolution with our newly developed surface flux transport model. We investigate three different cases: a constant average meridional flow, the observed time-varying meridional flow, and a time-varying meridional flow in which the observed variations from the average have been doubled. Comparison of these simulations shows that the variationsmore » in the meridional flow over cycle 23 have a significant impact (∼20%) on the polar fields. However, the variations produced polar fields that were stronger than they would have been otherwise. We propose that the primary cause of the extended cycle 23/24 minimum and weak cycle 24 was the weakness of cycle 23 itself—with fewer sunspots, there was insufficient flux to build a big cycle. We also find that any polar counter-cells in the meridional flow (equatorward flow at high latitudes) produce flux concentrations at mid-to-high latitudes that are not consistent with observations.« less

Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella

PubMed Central

Duménil, Claire; Judd, Gary J. R.; Bosch, Dolors; Baldessari, Mario; Gemeno, César; Groot, Astrid T.

2014-01-01

The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption. PMID:26462935

Comparative population genomics of latitudinal variation in Drosophila simulans and Drosophila melanogaster

PubMed Central

MACHADO, HEATHER E.; BERGLAND, ALAN O.; O’BRIEN, KATHERINE R.; BEHRMAN, EMILY L.; SCHMIDT, PAUL S.; PETROV, DMITRI A.

2016-01-01

Examples of clinal variation in phenotypes and genotypes across latitudinal transects have served as important models for understanding how spatially varying selection and demographic forces shape variation within species. Here, we examine the selective and demographic contributions to latitudinal variation through the largest comparative genomic study to date of Drosophila simulans and Drosophila melanogaster, with genomic sequence data from 382 individual fruit flies, collected across a spatial transect of 19 degrees latitude and at multiple time points over 2 years. Consistent with phenotypic studies, we find less clinal variation in D. simulans than D. melanogaster, particularly for the autosomes. Moreover, we find that clinally varying loci in D. simulans are less stable over multiple years than comparable clines in D. melanogaster. D. simulans shows a significantly weaker pattern of isolation by distance than D. melanogaster and we find evidence for a stronger contribution of migration to D. simulans population genetic structure. While population bottlenecks and migration can plausibly explain the differences in stability of clinal variation between the two species, we also observe a significant enrichment of shared clinal genes, suggesting that the selective forces associated with climate are acting on the same genes and phenotypes in D. simulans and D. melanogaster. PMID:26523848

Intraspecific Variation in Female Sex Pheromone of the Codling Moth Cydia pomonella.

PubMed

Duménil, Claire; Judd, Gary J R; Bosch, Dolors; Baldessari, Mario; Gemeno, César; Groot, Astrid T

2014-09-26

The codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), is a major pest of apple, pear and walnut orchards worldwide. This pest is often controlled using the biologically friendly control method known as pheromone-based mating disruption. Mating disruption likely exerts selection on the sexual communication system of codling moth, as male and female moths will persist in their attempt to meet and mate. Surprisingly little is known on the intraspecific variation of sexual communication in this species. We started an investigation to determine the level of individual variation in the female sex pheromone composition of this moth and whether variation among different populations might be correlated with use of mating disruption against those populations. By extracting pheromone glands of individual females from a laboratory population in Canada and from populations from apple orchards in Spain and Italy, we found significant between- and within-population variation. Comparing females that had been exposed to mating disruption, or not, revealed a significant difference in sex pheromone composition for two of the minor components. Overall, the intraspecific variation observed shows the potential for a shift in female sexual signal when selection pressure is high, as is the case with continuous use of mating disruption.

Variations in Near-Infrared Emissivity of Venus Surface Observed by the Galileo Near-Infrared Mapping Spectrometer

NASA Astrophysics Data System (ADS)

Hashimoto, G. L.; Roos-Serote, M.; Sugita, S.

2004-11-01

We evaluate the spatial variation of venusian surface emissivity at a near-infrared wavelength using multispectral images obtained by the Near-Infrared Mapping Spectrometer (NIMS) on board the Galileo spacecraft. The Galileo made a close flyby to Venus in February 1990. During this flyby, NIMS observed the nightside of Venus with 17 spectral channels, which includes the well-known spectral windows at 1.18, 1.74, and 2.3 μ m. The surface emissivity is evaluated at 1.18 μ m, at which thermal radiation emitted from the planetary surface could be detected. To analyze the NIMS observations, synthetic spectra have been generated by means of a line-by-line radiative transfer program which includes both scattering and absorption. We used the discrete ordinate method to calculate the spectra of vertically inhomogeneous plane-parallel atmosphere. Gas opacity is calculated based on the method of Pollack et al. (1993), though binary absorption coefficients for continuum opacity are adjusted to achieve an acceptable fit to the NIMS data. We used Mie scattering theory and a cloud model developed by Pollack et al. (1993) to determine the single scattering albedo and scattering phase function of the cloud particles. The vertical temperature profile of Venus International Reference Atmosphere (VIRA) is used in all our calculations. The procedure of the analysis is the followings. We first made a correction for emission angle. Then, a modulation of emission by the cloud opacities is removed using simultaneously measured 1.74 and 2.3 μ m radiances. The resulting images are correlated with the topographic map of Magellan. To search for variations in surface emissivity, this cloud corrected images are divided by synthetic radiance maps that were created from the Magellan data. This work has been supported by The 21st Century COE Program of Origin and Evolution of Planetary Systems of Ministry of Education, Culture, Sports, Science and Technology (MEXT).

Observation and simulation of near-surface wind and its variation with topography in Urumqi, West China

NASA Astrophysics Data System (ADS)

Jin, Lili; Li, Zhenjie; He, Qing; Miao, Qilong; Zhang, Huqiang; Yang, Xinghua

2016-12-01

Near-surface wind measurements obtained with five 100-m meteorology towers, 39 regional automatic stations, and simulations by the Weather Research and Forecasting (WRF) model were used to investigate the spatial structure of topography-driven flows in the complex urban terrain of Urumqi, China. The results showed that the wind directions were mainly northerly and southerly within the reach of 100 m above ground in the southern suburbs, urban area, and northern suburbs, which were consistent with the form of the Urumqi gorge. Strong winds were observed in southern suburbs, whereas the winds in the urban, northern suburbs, and northern rural areas were weak. Static wind occurred more frequently in the urban and northern rural areas than in the southern suburbs. In the southern suburbs, wind speed was relatively high throughout the year and did not show significant seasonal variations. The average annual wind speed in this region varied among 1.9-5.5, 1.1-3.6, 1.2-4.3, 1.2-4.3, and 1.1-3.5 m s -1 within the reach of 100 m above ground at Yannanlijiao, Shuitashan, Liyushan, Hongguangshan, and Midong, respectively. The flow characteristics comprised more airflows around the mountain, where the convergence and divergence were dominated by the terrain in eastern and southwestern Urumqi. Further analysis showed that there was a significant mountain-valley wind in spring, summer, and autumn, which occurred more frequently in spring and summer for 10-11 h in urban and northern suburbs. During daytime, there was a northerly valley wind, whereas at night there was a southerly mountain wind. The conversion time from the mountain wind to the valley wind was during 0800-1000 LST (Local Standard Time), while the conversion from the valley wind to the mountain wind was during 1900-2100 LST. The influence of the mountain-valley wind in Urumqi City was most obvious at 850 hPa, according to the WRF model.

Clinical significance of circumportal pancreas, a rare congenital anomaly, in pancreatectomy.

PubMed

Ohtsuka, Takao; Mori, Yasuhisa; Ishigami, Kousei; Fujimoto, Takaaki; Miyasaka, Yoshihiro; Nakata, Kohei; Ohuchida, Kenoki; Nagai, Eishi; Oda, Yoshinao; Shimizu, Shuji; Nakamura, Masafumi

2017-08-01

Circumportal pancreas is a rare congenital pancreatic anomaly. The aim of this study was to clarify the clinical characteristics of patients with circumportal pancreases undergoing pancreatectomy. The medical records of 508 patients who underwent pancreatectomy were retrospectively reviewed. The prevalence of circumportal pancreas and related anatomical variations were assessed. Surgical procedures and postoperative outcomes were compared in patients with and without circumportal pancreas. Circumportal pancreas was observed in 9 of the 508 patients (1.7%). In all nine patients, the portal vein was completely encircled by the pancreatic parenchyma above the level of the splenoportal junction, and the main pancreatic duct ran dorsal to the portal vein. The rate of variant hepatic artery did not differ significantly in patients with and without circumportal pancreas. Pancreatic fistula developed more frequently in patients with than without circumportal pancreas (44% vs. 14%, p = 0.03), but other clinical parameters did not differ significantly in these two groups. Despite being rare, circumportal pancreas may increase the risk of postoperative pancreatic fistula in patients undergoing pancreatectomy. However, a prospective, large-cohort study is necessary to determine the real incidence of relevant anatomical variations and the definitive clinical significance of this rare anomaly. Copyright © 2016 Elsevier Inc. All rights reserved.

Variations in the long-term uplift rate due to the Altiplano-Puna magma body observed with Sentinel-1 interferometry

NASA Astrophysics Data System (ADS)

Lau, Nicholas; Tymofyeyeva, Ekaterina; Fialko, Yuri

2018-06-01

We present new Interferometric Synthetic Aperture Radar (InSAR) observations of surface deformation in the Altiplano-Puna region (South America) where previous studies documented a broad uplift at an average rate of ∼10 mm/yr. We use data from the Sentinel-1 satellite mission to produce high-resolution velocity maps and time series of surface displacements between years 2014-2017. The data reveal that the uplift has slowed down substantially compared to the 1992-2010 epoch and is characterized by short-term fluctuations on time scales of months to years. The observed variations in uplift rate may indicate a non-steady supply of melt and/or volatiles from the partially molten Altiplano-Puna Magma Body (APMB) into an incipient diapir forming in the roof of the APMB.

Background Noises Versus Intraseasonal Variation Signals: Small vs. Large Convective Cloud Objects From CERES Aqua Observations

NASA Technical Reports Server (NTRS)

Xu, Kuan-Man

2015-01-01

During inactive phases of Madden-Julian Oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES (Clouds and the Earth's Radiant Energy System) observations between July 2006 and June 2010 for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index, which assigns the tropics to one of the eight MJO phases each day. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The criteria for defining these cloud types are overcast footprints and cloud top pressures less than 400 hPa, but DC has higher cloud optical depths (=10) than those of CS (<10). The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In

Near-infrared observations of the variable crab nebula

NASA Astrophysics Data System (ADS)

Yamamoto, M.; Mori, K.; Shibata, S.; Tsujimoto, M.; Misawa, T.; Burrows, D.; Kawai, N.

We present three near-infrared NIR observations of the Crab Nebula obtained with CISCO on the Subaru Telescope and Quick Infrared Camera on the University of HAWAII 88 inch Telescope The observations were performed on 2004 September 2005 February and 2005 October and were coordinated with X-ray observations obtained with the Chandra X-ray observatory within 10 days As shown in previous optical and X-ray monitoring observations outward-moving wisps and variable knots are detected also in our NIR observations The NIR variations are closely correlated with variations in the X-ray observations indicating that both variations are driven by the same physical process We discuss the origin of NIR-emitting particles based on the temporal variations as well as the spectral energy distributions of each variable component

Longitudinal variation in lateral trapping of fine sediment in tidal estuaries: observations and a 3D exploratory model

NASA Astrophysics Data System (ADS)

Chen, Wei; de Swart, Huib E.

2018-03-01

This study investigates the longitudinal variation of lateral entrapment of suspended sediment, as is observed in some tidal estuaries. In particular, field data from the Yangtze Estuary are analysed, which reveal that in one cross-section, two maxima of suspended sediment concentration (SSC) occur close to the south and north sides, while in a cross-section 2 km down-estuary, only one SSC maximum on the south side is present. This pattern is found during both spring tide and neap tide, which are characterised by different intensities of turbulence. To understand longitudinal variation in lateral trapping of sediment, results of a new three-dimensional exploratory model are analysed. The hydrodynamic part contains residual flow due to fresh water input, density gradients and Coriolis force and due to channel curvature-induced leakage. Moreover, the model includes a spatially varying eddy viscosity that accounts for variation of intensity of turbulence over the spring-neap cycle. By imposing morphodynamic equilibrium, the two-dimensional distribution of sediment in the domain is obtained analytically by a novel procedure. Results reveal that the occurrence of the SSC maxima near the south side of both cross-sections is due to sediment entrapment by lateral density gradients, while the second SSC maximum near the north side of the first cross-section is by sediment transport due to curvature-induced leakage. Coriolis deflection of longitudinal flow also contributes the trapping of sediment near the north side. This mechanism is important in the upper estuary, where the flow due to lateral density gradients is weak.

Seasonal to Decadal Variations of Water Vapor in the Tropical Lower Stratosphere Observed with Balloon-Borne Cryogenic Frost Point Hygrometers

NASA Technical Reports Server (NTRS)

Fujiwara, M.; Voemel, H.; Hasebe, F.; Shiotani, M.; Ogino, S.-Y.; Iwasaki, S.; Nishi, N.; Shibata, T.; Shimizu, K.; Nishimoto, E.;

Genotypic variation in transpiration efficiency due to differences in photosynthetic capacity among sugarcane-related clones.

PubMed

Li, Chunjia; Jackson, Phillip; Lu, Xin; Xu, Chaohua; Cai, Qing; Basnayake, Jayapathi; Lakshmanan, Prakash; Ghannoum, Oula; Fan, Yuanhong

2017-04-01

Sugarcane, derived from the hybridization of Saccharum officinarum×Saccharum spontaneum, is a vegetative crop in which the final yield is highly driven by culm biomass production. Cane yield under irrigated or rain-fed conditions could be improved by developing genotypes with leaves that have high intrinsic transpiration efficiency, TEi (CO2 assimilation/stomatal conductance), provided this is not offset by negative impacts from reduced conductance and growth rates. This study was conducted to partition genotypic variation in TEi among a sample of diverse clones from the Chinese collection of sugarcane-related germplasm into that due to variation in stomatal conductance versus that due to variation in photosynthetic capacity. A secondary goal was to define protocols for optimized larger-scale screening of germplasm collections. Genotypic variation in TEi was attributed to significant variation in both stomatal and photosynthetic components. A number of genotypes were found to possess high TEi as a result of high photosynthetic capacity. This trait combination is expected to be of significant breeding value. It was determined that a small number of observations (16) is sufficient for efficiently screening TEi in larger populations of sugarcane genotypes The research methodology and results reported are encouraging in supporting a larger-scale screening and introgression of high transpiration efficiency in sugarcane breeding. However, further research is required to quantify narrow sense heritability as well as the leaf-to-field translational potential of genotypic variation in transpiration efficiency-related traits observed in this study. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Measurement of carbon nanotube microstructure relative density by optical attenuation and observation of size-dependent variations.

PubMed

Park, Sei Jin; Schmidt, Aaron J; Bedewy, Mostafa; Hart, A John

2013-07-21

Engineering the density of carbon nanotube (CNT) forest microstructures is vital to applications such as electrical interconnects, micro-contact probes, and thermal interface materials. For CNT forests on centimeter-scale substrates, weight and volume can be used to calculate density. However, this is not suitable for smaller samples, including individual microstructures, and moreover does not enable mapping of spatial density variations within the forest. We demonstrate that the relative mass density of individual CNT microstructures can be measured by optical attenuation, with spatial resolution equaling the size of the focused spot. For this, a custom optical setup was built to measure the transmission of a focused laser beam through CNT microstructures. The transmittance was correlated with the thickness of the CNT microstructures by Beer-Lambert-Bouguer law to calculate the attenuation coefficient. We reveal that the density of CNT microstructures grown by CVD can depend on their size, and that the overall density of arrays of microstructures is affected significantly by run-to-run process variations. Further, we use the technique to quantify the change in CNT microstructure density due to capillary densification. This is a useful and accessible metrology technique for CNTs in future microfabrication processes, and will enable direct correlation of density to important properties such as stiffness and electrical conductivity.

Variations in solar Lyman alpha irradiance on short time scales

NASA Astrophysics Data System (ADS)

Pap, J. M.

1992-10-01

Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

Variations in solar Lyman alpha irradiance on short time scales

NASA Technical Reports Server (NTRS)

Pap, J. M.

1992-01-01

Variations in solar UV irradiance at Lyman alpha are studied on short time scales (from days to months) after removing the long-term changes over the solar cycle. The SME/Lyman alpha irradiance is estimated from various solar indices using linear regression analysis. In order to study the nonlinear effects, Lyman alpha irradiance is modeled with a 5th-degree polynomial as well. It is shown that the full-disk equivalent width of the He line at 1083 nm, which is used as a proxy for the plages and active network, can best reproduce the changes observed in Lyman alpha. Approximately 72 percent of the solar-activity-related changes in Lyman alpha irradiance arise from plages and the network. The network contribution is estimated by the correlation analysis to be about 19 percent. It is shown that significant variability remains in Lyman alpha irradiance, with periods around 300, 27, and 13.5d, which is not explained by the solar activity indices. It is shown that the nonlinear effects cannot account for a significant part of the unexplained variation in Lyman alpha irradiance. Therefore, additional events (e.g., large-scale motions and/or a systematic difference in the area and intensity of the plages and network observed in the lines of Ca-K, He 1083, and Lyman alpha) may explain the discrepancies found between the observed and estimated irradiance values.

Global X-ray Spectral Variation of Eta Carinae through the 2003 X-ray Minimum

NASA Technical Reports Server (NTRS)

Hamaguchi, K.; Corcoran, M. F.; White, N. E.; Gull, T.; Damineli, A.; Davidson, K.

2006-01-01

We report on the results of the X-ray observing campaign of the massive, evolved star Eta Carinae in 2003 around its recent X-ray Minimum, mainly using data from the XMM-Newton observatory. These imaging observations show that the hard X-ray source associated with the Eta Carinae system does not completely disappear in any of the observations during the Minimum. The variation of the spectral shape revealed two emission components. One newly discovered component did not exhibit any variation on kilo-second to year-long timescales, in a combined analysis with earlier ASCA and ROSAT data, and might represent the collision of a high speed outflow from Eta Carinae with ambient gas clouds. The other emission component was strongly variable in flux but the temperature of the hottest plasma did not vary significantly at any orbital phase. Absorption to the hard emission, was about a factor of three larger than the absorption determined from the cutoff of the soft emission, and reached a maximum of approx.4 x 10(exp 23)/sq cm before the Minimum. The thermal Fe\\rm XXV emission line showed significant excesses on both the red and blue sides of the line outside the Minimum and exhibited a large redward excess during the Minimum. This variation in the line profile probably requires an abrupt change in ionization balance in the shocked gas.

Seasonal variation in the international normalized ratio of neonates and its relationship with ambient temperature.

PubMed

Iijima, Shigeo; Sekii, Katsuyuki; Baba, Toru; Ueno, Daizo; Ohishi, Akira

2016-07-19

The morbidity and mortality rates due to cardiovascular events such as myocardial infarction are known to exhibit seasonal variations. Moreover, changes in the ambient temperature are reportedly associated with an increase in these events, which may potentially involve blood coagulation markers. Bleeding due to vitamin K deficiency in neonates, which is associated with high mortality and a high frequency of neurological sequelae, is more commonly observed during the summer season and in warm regions in Japan. To determine the presence of seasonal variation and the influence of ambient temperature on blood coagulation markers in healthy term neonates, we assessed the international normalized ratio (INR) values measured using CoaguChek XS. We studied 488 consecutive healthy term neonates who were born at a perinatal center between July 2012 and June 2013. The INR values were measured using CoaguChek XS in 4-day-old neonates who received nursing care in the newborn nursery throughout the duration of hospitalization. The seasonal variations in the INR values and environmental effects on the INR were assessed. The mean monthly INR values peaked in July (1.13 ± 0.08), whereas the lowest values were observed in January (1.05 ± 0.08). Higher levels of INR were observed during the summer season (June to August) than during the winter season (December to February). Simple linear regression analysis indicated the presence of weakly positive but significant correlations between INR and outdoor temperature (r = 0.25, p < 0.001), outdoor relative humidity (r = 0.19, p < 0.001), and room relative humidity (r = 0.24, p < 0.001), and the presence of a significant negative correlation between INR and room temperature (r = -0.13, p = 0.02). Furthermore, multiple linear regression analysis showed that only outdoor temperature significantly influenced the INR. A seasonal variation in the INR values was observed among neonates, possibly due to

Deglaciation-induced uplift and seasonal variations patterns of bedrock displacement in Greenland ice sheet margin observed from GPS, GRACE and InSAR

NASA Astrophysics Data System (ADS)

Lu, Q.; Amelung, F.; Wdowinski, S.

2017-12-01

The Greenland ice sheet is rapidly shrinking with the fastest retreat and thinning occurring at the ice sheet margin and near the outlet glaciers. The changes of the ice mass cause an elastic response of the bedrock. Theoretically, ice mass loss during the summer melting season is associated with bedrock uplift, whereas increasing ice mass during the winter months is associated with bedrock subsidence. Here we examine the annual changes of the vertical displacements measured at 37 GPS stations and compare the results with Greenland drainage basins' gravity from GRACE. We use both Fourier Series (FS) analysis and Cubic Smoothing Spline (CSS) method to estimate the phases and amplitudes of seasonal variations. Both methods show significant differences seasonal behaviors in southern and northern Greenland. The average amplitude of bedrock displacements (3.29±0.02mm) in south Greenland is about 2 times larger than the north (1.65±0.02mm). The phase of bedrock maximum uplift (November) is considerably consistent with the time of minimum ice mass load in south Greenland (October). However, the phase of bedrock maximum uplift in north Greenland (February) is 4 months later than the minimum ice mass load in north Greenland basins (October). In addition, we present ground deformation near several famous glaciers in Greenland such as Petermann glacier and Jakobshavn glacier. We process InSAR data from TerraSAR-X and Sentinel satellite, based on small baseline interferograms. We observed rapid deglaciation-induced uplift and seasonal variations on naked bedrock near the glacier ice margin.

The impact of nectar chemical features on phenotypic variation in two related nectar yeasts.

PubMed

Pozo, María I; Herrera, Carlos M; Van den Ende, Wim; Verstrepen, Kevin; Lievens, Bart; Jacquemyn, Hans

2015-06-01

Floral nectars become easily colonized by microbes, most often species of the ascomycetous yeast genus Metschnikowia. Although it is known that nectar composition can vary tremendously among plant species, most probably corresponding to the nutritional requirements of their main pollinators, far less is known about how variation in nectar chemistry affects intraspecific variation in nectarivorous yeasts. Because variation in nectar traits probably affects growth and abundance of nectar yeasts, nectar yeasts can be expected to display large phenotypic variation in order to cope with varying nectar conditions. To test this hypothesis, we related variation in the phenotypic landscape of a vast collection of nectar-living yeast isolates from two Metschnikowia species (M. reukaufii and M. gruessii) to nectar chemical traits using non-linear redundancy analyses. Nectar yeasts were collected from 19 plant species from different plant families to include as much variation in nectar chemical traits as possible. As expected, nectar yeasts displayed large variation in phenotypic traits, particularly in traits related to growth performance in carbon sources and inhibitors, which was significantly related to the host plant from which they were isolated. Total sugar concentration and relative fructose content significantly explained the observed variation in the phenotypic profile of the investigated yeast species, indicating that sugar concentration and composition are the key traits that affect phenotypic variation in nectarivorous yeasts. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Latitudinal dependence of diurnal and seasonal variations in the tropospheric zenith delay observed from GPS measurements within the longitudinal sector of 50oE to 130oE.

NASA Astrophysics Data System (ADS)

Raju, Suresh; Saha, Korak; Anupama, K.; Parameswaran, Krishnaswamy

Ground based GPS finds potential applications in many atmospheric studies such as the spatial distribution of columnar water vapor as well as tidal oscillations in the atmosphere. As the zenith tropospheric delay (ZTD) derived from GPS data is a function of atmospheric pressure, temperature and watervapor, the effect of atmospheric oscillations could reflect more promi-nently in its temporal variations. The GPS data with very high temporal resolution (5 min.) from thirteen IGS stations in the longitudinal sector of 50o-130oE are used to establish its potential for studying the atmospheric tidal, intra-seasonal and planetary oscillations. Very prominent tidal (diurnal and semi-diurnal) oscillations observed at all these stations, with am-plitude of the diurnal variation as ˜0.5-12+0.5 mm and that of the semi-diurnal variation in the range ˜0.1-5+0.2 mm. Although 90% of the delay is contributed by the dry atmospheric pressure (which shows prominent semi-diurnal oscillations) the tidal oscillations in the ZTD is dominated by the diurnal component. This effect could be attributed to the temporal variations of atmospheric water vapor in a diurnal scale. The amplitude of these variations in general is largest near the equator and decreases with increase in latitude. Interestingly, this latitudinal trend matches very well with the latitude variation of the precipitable water vapor (as well as the actual precipitation) in this longitudinal region. Though the values of ZTD at stations very close to equator stations do not show any prominent seasonal variation, as the latitude increases the annual variation in ZTD becomes more distinct. A prominent peak in ZTD is observed during the July-August period, which matches well with the annual variation of atmospheric water vapor. This shows that the diurnal and seasonal variation of ZTD is mainly governed by the corresponding variations in atmospheric water vapor, even though its contribution to the total delay is around 10

The Genetic Basis of Natural Variation in Caenorhabditis elegans Telomere Length

PubMed Central

Cook, Daniel E.; Zdraljevic, Stefan; Tanny, Robyn E.; Seo, Beomseok; Riccardi, David D.; Noble, Luke M.; Rockman, Matthew V.; Alkema, Mark J.; Braendle, Christian; Kammenga, Jan E.; Wang, John; Kruglyak, Leonid; Félix, Marie-Anne; Lee, Junho; Andersen, Erik C.

2016-01-01

Telomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligonucleotide/oligosaccharide-binding fold of protection of telomeres 2 (POT-2), a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans. PMID:27449056

The Genetic Basis of Natural Variation in Caenorhabditis elegans Telomere Length.

PubMed

Cook, Daniel E; Zdraljevic, Stefan; Tanny, Robyn E; Seo, Beomseok; Riccardi, David D; Noble, Luke M; Rockman, Matthew V; Alkema, Mark J; Braendle, Christian; Kammenga, Jan E; Wang, John; Kruglyak, Leonid; Félix, Marie-Anne; Lee, Junho; Andersen, Erik C

2016-09-01

Telomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligonucleotide/oligosaccharide-binding fold of protection of telomeres 2 (POT-2), a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans. Copyright © 2016 by the Genetics Society of America.

Effects of Faraday Rotation Observed in Filter Magnetograph Data

NASA Technical Reports Server (NTRS)

Hagyard, Mona J.; Adams, Mitzi L.; Smith, J. E.; West, Edward A.

1999-01-01

In this paper we analyze the effects of Faraday rotation on the azimuth of the transverse magnetic field from observations taken with the Marshall Space Flight Center's vector magnetograph for a simple sunspot observed on June 9, 1985. Vector magnetograms were obtained over the wavelength interval of 170 mA redward of line center of the Fe I 5250.22 A spectral line to 170 mA to the blue, in steps of 10 mA. These data were analyzed to produce the variation of the azimuth as a function of wavelength at each pixel over the field of vi ew of the sunspot. At selected locations in the sunspot, curves of the observed variation of azimuth with wavelength were compared with model calculations for the amount of Faraday rotation of the azimuth. From these comparisons we derived the amount of rotation as functions of bo th the magnitude and inclination of the sunspot's field and deduced the ranges of these field values for which Faraday rotation presents a significant problem in observations taken near the center of a spectral line.

Image enhancement filters significantly improve reading performance for low vision observers

NASA Technical Reports Server (NTRS)

Lawton, T. B.

1992-01-01

As people age, so do their photoreceptors; many photoreceptors in central vision stop functioning when a person reaches their late sixties or early seventies. Low vision observers with losses in central vision, those with age-related maculopathies, were studied. Low vision observers no longer see high spatial frequencies, being unable to resolve fine edge detail. We developed image enhancement filters to compensate for the low vision observer's losses in contrast sensitivity to intermediate and high spatial frequencies. The filters work by boosting the amplitude of the less visible intermediate spatial frequencies. The lower spatial frequencies. These image enhancement filters not only reduce the magnification needed for reading by up to 70 percent, but they also increase the observer's reading speed by 2-4 times. A summary of this research is presented.

Genetic variation in the ASIC3 gene influences blood pressure levels in Taiwanese.

PubMed

Ko, Yu-Lin; Hsu, Lung-An; Wu, Semon; Teng, Ming-Sheng; Chang, Hsien-Hsun; Chen, Chih-Cheng; Cheng, Ching-Feng

2008-11-01

The acid-sensing ion channel 3 (ASIC3) is a ligand-gated cation channel activated by extracellular protons, and is associated with an exercise-induced pressor reflex and possibly autonomic imbalance. To test the statistical association between genetic polymorphisms of the ASIC3 gene and blood pressure (BP) variations in Taiwanese, 551 unrelated individuals (286 men and 265 women) were recruited from a routine health examination. The participants had no prior history of cardiovascular disease or medication use for hypertension. Six ASIC3 gene polymorphisms were genotyped; three were polymorphic, and only the rs2288646 polymorphism was associated with variations in BP among participants. Significantly higher systolic, diastolic, and mean BP were observed in participants carrying the rs2288646-A allele (P=0.034, 0.023, and 0.010, respectively). Significantly higher frequencies of the rs2288646-A-containing genotype were observed in normotensive, prehypertensive, and hypertensive subgroups (P for trend=0.026); and in those with higher systolic and diastolic BPs (P for trend=0.005 and P for trend=0.002, respectively). The association between the rs2288646-A allele and BP persisted even after adjustment for age, sex, BMI, and other metabolic factors. When a second independent group of 403 individuals was combined with the first group of 551 (n=954), a significantly higher frequency of the rs2288646-A-containing genotype was observed in participants with hypertension (9.7 vs. 4.0%, P=0.003). Our data showed an independent association between an ASIC3 genetic polymorphism and BP variations in Taiwanese. These results suggest that the ASIC3 may be involved in BP regulation.

[Variations of peripheral blood autoantibody, immunoglobuliln, and complement levels in patients with non-lactational mastitis and their clinical significances].

PubMed

Xu, Rui; Guo, Qian-Qian; Yang, Le-Ping; Lai, Mi-Lin; Tong, Lin

2016-08-20

To detect the variations in peripheral blood levels of autoantibodies, immunoglobulilns and complements in patients with non-lactational mastitis and investigate whether non-lactational mastitis is an autoimmune disease with immune dysfunction. Seven-eight patients with non-lactational mastitis treated in our hospital between September 2013 and May 2015 and 88 healthy women (control) were examined for peripheral blood levels of antinuclear antibody (ANA), anti-histone antibody (AHA), immunoglobulins (IgA, IgM, and IgG) and complements (C3, C4, and total complements). s Of the 78 patients with non-lactational mastitis, 50 (64.10%) were positive of ANA showing mainly the granular and cytoplasmic granular fluorescence patterns, and the positivity rate was significantly higher than that in the control group (P<0.000). Twenty-eight (36.00%) of the patients were positive of AHA, a rate significantly higher than that in the control group (P<0.000). The levels of IgA, IgM, C4, and total complements levels were all significantly elevated in the patients compared with those in the control group (P<0.05). Patients with non-lactational mastitis have abnormal changes in peripheral blood levels of immunoglobulins and complements with high positivity rates for ANA and AHA, indicating that non-lactational mastitis is an autoimmune disease with immune dysfunction.

Human-Induced Climate Variations Linked to Urbanization: From Observations to Modeling

NASA Technical Reports Server (NTRS)

Shepherd, J. Marshall; Jin, Menglin

2004-01-01

The goal of this session is to bring together scientists from interdisciplinary backgrounds to discuss the data, scientific approaches and recent results focusing on the impact of urbanization on the climate. The discussion will highlight current observational and modeling capabilities being employed for investigating the urban environment and its linkage to the change in the Earth's climate system. The goal of the session is to identify our current stand and the future direction on the topic. Urbanization is one of the extreme cases of land use change. Most of population of the world has moved to urban areas. By 1995, more than 70% of population of North America and Europe were living in cities. By 2025, the United Nations estimates that 60% of the worlds population will live in cities. Although currently only 1.2% of the land is urban, better understanding of how the atmosphere-ocean-land-biosphere components interact as a coupled system and the influence of human activities on this system is critical. Our understanding of urbanization effect is incomplete, partly because human activities induce new changes on climate in addition to the original natural variations, and partly because previously few data available for study urban effect globally. Urban construction changes surface roughness, albedo, heat capacity and vegetation coverage. Traffic and industry increase atmospheric aerosol. It is suggested that urbanization may modify rainfall processes through aerosol-cloud interactions or dynamic feedbacks. Because urbanization effect on climate is determined by many factors including land cover, the city's microscale features, population density, and human lifestyle patterns, it is necessary to study urban areas over globe.

Period Variations for the Cepheid VZ Cyg

NASA Astrophysics Data System (ADS)

Sirorattanakul, Krittanon; Engle, Scott; Pepper, Joshua; Wells, Mark; Laney, Clifton D.; Rodriguez, Joseph E.; Stassun, Keivan G.

2017-12-01

The Cepheid Period-Luminosity law is a key rung on the extragalactic distance ladder. However, numerous Cepheids are known to undergo period variations. Monitoring, refining, and understanding these period variations allows us to better determine the parameters of the Cepheids themselves and of the instability strip in which they reside, and to test models of stellar evolution. VZ Cyg, a classical Cepheid pulsating at ˜4.864 days, has been observed for over 100 years. Combining data from literature observations, the Kilodegree Extremely Little Telescope (KELT) transit survey, and new targeted observations with the Robotically Controlled Telescope (RCT) at Kitt Peak, we find a period change rate of dP/dt = -0.0642 ± 0.0018 s yr-1. However, when only the recent observations are examined, we find a much higher period change rate of dP/dt = -0.0923 ± 0.0110 s yr-1. This higher rate could be due to an apparent long-term (P ≈ 26.5 years) cyclic period variation. The possible interpretations of this single Cepheid’s complex period variations underscore both the need to regularly monitor pulsating variables and the important benefits that photometric surveys such as KELT can have on the field. Further monitoring of this interesting example of Cepheid variability is recommended to confirm and better understand the possible cyclic period variations. Further, Cepheid timing analyses are necessary to fully understand their current behaviors and parameters, as well as their evolutionary histories.

Case-mix fails to explain variation in mastectomy rates: management of screen-detected breast cancer in a UK region 1997–2003

PubMed Central

Caldon, L J M; Walters, S J; Reed, J A; Murphy, A; Worley, A; Reed, M W R

2004-01-01

Wide variation in the surgical management of breast cancer exists at hospital, regional, national and international level. To demonstrate whether variation in surgical practice observed at aggregate level between breast units persists following adjustment for case-mix, individual patient-level data from the Trent Breast Screening Programme Quality Assurance database (1997–2003) was analysed. Expected case-mix adjusted mastectomy rates were derived by logistic regression using the variables tumour size, site and grade, patient age and year of presentation, employing the region's overall case-mix adjusted practice as the reference population. The region's 11 breast screening units detected 5109 (3989 invasive) surgically managed primary breast cancers over the 6-year period. A total of 1828 mastectomies (Mx) were performed (Mx rate 35.8%, 95% confidence interval: 34.5–37.1%). Significant variation in mastectomy rates were observed between units (range 25–45%, P<0.0001), and persists following case-mix adjustment (P<0.0001). Two-fold variation in observed to expected unit mastectomy rate coefficient is demonstrated overall (range 0.66–1.36), increasing to almost four-fold variation in cancers less than 15 mm diameter (range 0.55–1.95). Significant variation in surgery for screen-detected primary breast cancer is not explained by case-mix. Further research is required to investigate potential patient and professional causative factors. PMID:15611797

Spacebased Observations of Oceanic Influence on the Annual Variation of South American Water Balance

NASA Technical Reports Server (NTRS)

Liu, W. Timothy; Xie, Xiaosu; Tang, Wenqing; Zlotnicki, Victor

2006-01-01

The mass change of South America (SA) continent measured by the Gravity Recovery and Climate Experiment (GRACE) imposes a constraint on the uncertainties in estimating the annual variation of rainfall measured by Tropical Rain Measuring Mission (TRMM) and ocean moisture influx derived from QuikSCAT data. The approximate balance of the mass change rate with the moisture influx less climatological river discharge, in agreement with the conservation principle, bolsters not only the credibility of the spacebased measurements, but supports the characterization of ocean's influence on the annual variation of continental water balance. The annual variation of rainfall is found to be in phase with the mass change rate in the Amazon and the La Plata basins, and the moisture advection across relevant segments of the Pacific and Atlantic coasts agrees with the annual cycle of rainfall in the two basins and the Andes mountains.

Nineteenth century Parisian smoke variations inferred from Eiffel Tower atmospheric electrical observations

NASA Astrophysics Data System (ADS)

Harrison, R. G.; Aplin, K. L.

Atmospheric electrical measurements provide proxy data from which historic smoke pollution levels can be determined. This approach is applied to infer autumnal Parisian smoke levels in the 1890s, based on atmospheric electric potential measurements made at the surface and the summit of the Eiffel Tower (48.7°N, 2.4°E). A theoretical model of the development of the autumn convective boundary layer is used to determine when local pollution effects dominated the Eiffel Tower potential measurements. The diurnal variation of the Eiffel Tower potential showed a single oscillation, but it differs from the standard oceanic air potential gradient (PG) variations during the period 09-17 UT, when the model indicates that the Eiffel Tower summit should be within the boundary layer. Outside these hours, the potential changes closely follow the clean air PG variation: this finding is used to calibrate the Eiffel Tower measurements. The surface smoke pollution concentration found during the morning maximum was 60±30 μg m -3, substantially lower than the values previously inferred for Kew in 1863. A vertical smoke profile was also derived using a combination of the atmospheric electrical data and boundary layer meteorology theory. Midday smoke concentration decreased with height from 60 μg m -3 at the surface to 15 μg m -3 at the top of the Eiffel Tower. The 19th century PG measurements in both polluted and clean Parisian air present a unique resource for European air pollution and atmospheric composition studies, and early evidence of the global atmospheric electrical circuit.

Geographic variation in the black bear (Ursus americanus) in the eastern United States and Canada

USGS Publications Warehouse

Kennedy, M.L.; Kennedy, P.K.; Bogan, M.A.; Waits, J.L.

2002-01-01

The pattern of geographic variation in morphologic characters of the black bear (Ursus americanus) was assessed at 13 sites in the eastern United States and Canada. Thirty measurements from 206 males and 207 females were recorded to the nearest 0.01 mm using digital calipers and subjected to principal components analysis. A matrix of correlations among skull characters was computed, and the first 3 principal components were extracted. These accounted for 90.5% of the variation in the character set for males and 87.1% for females. Three-dimensional projection of localities onto principal components showed that, for males and females, largest individuals occurred in the more southern localities (e.g., males--Louisiana-Mississippi, eastern Texas; females--Louisiana-eastern Texas) and the smallest animals occurred in the northernmost locality (Quebec). Generally, bears were similar morphologically to those in nearby geographic areas. For males, correlations between morphologic variation and environmental factors indicated a significant relationship between size variation and mean January temperature, mean July temperature, mean annual precipitation, latitude, and actual evapotranspiration; for females, a significant relationship was observed between morphologic variation and mean annual temperature, mean January temperature, mean July temperature, latitude, and actual evapotranspiration. There was no significant correlation for either sex between environmental factors and projections onto components II and III.

Immunogenetic variation and differential pathogen exposure in free-ranging cheetahs across Namibian farmlands.

PubMed

Castro-Prieto, Aines; Wachter, Bettina; Melzheimer, Joerg; Thalwitzer, Susanne; Hofer, Heribert; Sommer, Simone

2012-01-01

Genes under selection provide ecologically important information useful for conservation issues. Major histocompatibility complex (MHC) class I and II genes are essential for the immune defence against pathogens from intracellular (e.g. viruses) and extracellular (e.g. helminths) origins, respectively. Serosurvey studies in Namibian cheetahs (Acinonyx juabuts) revealed higher exposure to viral pathogens in individuals from north-central than east-central regions. Here we examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs. Genetic variation at MHC I and II loci was assessed through single-stranded conformation polymorphism (SSCP) analysis and sequencing. While the overall allelic diversity did not differ, we observed a high genetic differentiation at MHC class I loci between cheetahs from north-central and east-central Namibia. No such differentiation in MHC class II and neutral markers were found. Our results suggest that MHC class I variation mirrors the variation in selection pressure imposed by viruses in free-ranging cheetahs across Namibian farmland. This is of high significance for future management and conservation programs of this species.

Auger electron intensity variations in oxygen-exposed large grain polycrystalline silver

NASA Technical Reports Server (NTRS)

Lee, W. S.; Outlaw, R. A.; Hoflund, G. B.; Davidson, M. R.

1989-01-01

Auger electron spectroscopic studies of the grains in oxygen-charged polycrystal-line silver show significant intensity variations as a function of crystallographic orientation. These intensity variations were observed by studies of the Auger images and line scans of the different grains (randomly selected) for each silver transition energy. The results can be attributed to the diffraction of the ejected Auger electrons and interpreted by corresponding changes in the electron mean-free path for inelastic scattering and by oxygen atom accumulation in the subsurface. The subsurface (second layer) octahedral sites increased in size because of surface relaxation and serve as a stable reservoir for the dissolved oxygen.

Sensitivity of surface meteorological analyses to observation networks

NASA Astrophysics Data System (ADS)

Tyndall, Daniel Paul

A computationally efficient variational analysis system for two-dimensional meteorological fields is developed and described. This analysis approach is most efficient when the number of analysis grid points is much larger than the number of available observations, such as for large domain mesoscale analyses. The analysis system is developed using MATLAB software and can take advantage of multiple processors or processor cores. A version of the analysis system has been exported as a platform independent application (i.e., can be run on Windows, Linux, or Macintosh OS X desktop computers without a MATLAB license) with input/output operations handled by commonly available internet software combined with data archives at the University of Utah. The impact of observation networks on the meteorological analyses is assessed by utilizing a percentile ranking of individual observation sensitivity and impact, which is computed by using the adjoint of the variational surface assimilation system. This methodology is demonstrated using a case study of the analysis from 1400 UTC 27 October 2010 over the entire contiguous United States domain. The sensitivity of this approach to the dependence of the background error covariance on observation density is examined. Observation sensitivity and impact provide insight on the influence of observations from heterogeneous observing networks as well as serve as objective metrics for quality control procedures that may help to identify stations with significant siting, reporting, or representativeness issues.

Modeling the Observed Solar Cycle Variations of the Quasi-biennial Oscillation (QBO): Amplification by Wave Forcing

NASA Technical Reports Server (NTRS)

Mayr, Hans G.; Mengel, John G.; Huang, Frank T.; Chan, Kwing L.

2007-01-01

In several papers, the solar cycle (SC) effect in the lower atmosphere has been linked observationally to the Quasi-biennial Oscillation (QBO) of the zonal circulation, which is generated primarily by small-scale gravity waves (GW). Salby and Callaghan (2000) in particular analyzed the QBO, covering more than 40 years, and discovered that it contains a large SC signature at 20 km. With our Numerical Spectral Model (NSM), we conducted a 3D study to describe the QBO under the influence of the SC, and some results have been published (Mayr et al., GRL, 2005,2006). For a SC period of 10 years, the relative amplitude of radiative forcing is taken to vary exponentially with height, i.e., 0.2% at the surface, 2% at 50 km, 20% at 100 km and above. Applying spectral analysis to filter out and identify the SC signature, the model generates a relatively large modulation of the QBO, which reproduces the observations qualitatively. Our numerical results demonstrate that the modulation of the QBO, with constant phase relative to the SC, persist at least for 60 years. The same model run generates in the seasonal variations a hemispherically symmetric Equatorial Annual Oscillation (EAO, with 12-month period), which is confined to low latitudes like the QBO and is also modulated by the SC. Although the amplitude of the EAO is relatively small, its SC modulation is large, and it is in phase with that of the QBO. The SC modulated EAO is evidently the pathway and pacemaker for the solar influence on the QBO. To shed light on the dynamical processes involved, we present model results that show how the seasonal cycle induces the SC modulations of the EAO and QBO. Our analysis further demonstrates that the SC modulations of the QBO and EAO are amplified by the GW interaction with the flow. The GW momentum source clearly shows a SC modulation that is in phase with the corresponding modulations of the QBO and EAO. By tapping the momentum from the upward propagating GWs, the QBO and EAO

“They Have to Adapt to Learn”: Surgeons’ Perspectives on the Role of Procedural Variation in Surgical Education

PubMed Central

Apramian, Tavis; Cristancho, Sayra; Watling, Chris; Ott, Michael; Lingard, Lorelei

2017-01-01

OBJECTIVE Clinical research increasingly acknowledges the existence of significant procedural variation in surgical practice. This study explored surgeons’ perspectives regarding the influence of intersurgeon procedural variation on the teaching and learning of surgical residents. DESIGN AND SETTING This qualitative study used a grounded theory-based analysis of observational and interview data. Observational data were collected in 3 tertiary care teaching hospitals in Ontario, Canada. Semistructured interviews explored potential procedural variations arising during the observations and prompts from an iteratively refined guide. Ongoing data analysis refined the theoretical framework and informed data collection strategies, as prescribed by the iterative nature of grounded theory research. PARTICIPANTS Our sample included 99 hours of observation across 45 cases with 14 surgeons. Semistructured, audio-recorded interviews (n = 14) occurred immediately following observational periods. RESULTS Surgeons endorsed the use of intersurgeon procedural variations to teach residents about adapting to the complexity of surgical practice and the norms of surgical culture. Surgeons suggested that residents’ efforts to identify thresholds of principle and preference are crucial to professional development. Principles that emerged from the study included the following: (1) knowing what comes next, (2) choosing the right plane, (3) handling tissue appropriately, (4) recognizing the abnormal, and (5) making safe progress. Surgeons suggested that learning to follow these principles while maintaining key aspects of surgical culture, like autonomy and individuality, are important social processes in surgical education. CONCLUSIONS Acknowledging intersurgeon variation has important implications for curriculum development and workplace-based assessment in surgical education. Adapting to intersurgeon procedural variations may foster versatility in surgical residents. However, the

Variation in pediatric outpatient adenotonsillectomy costs in a multihospital network.

PubMed

Meier, Jeremy D; Zhang, Yingying; Greene, Tom H; Curtis, Jonathan L; Srivastava, Rajendu

2015-05-01

Identify hospital costs for same-day pediatric adenotonsillectomy (T&A) surgery, and evaluate surgeon, hospital, and patient factors influencing variation in costs, and compare relationship of costs to complications for T&A. Observational retrospective cohort study. A multihospital network's standardized activity-based accounting system was used to determine hospital costs per T&A from 1998 to 2012. Children 1 to 18 years old who underwent same-day T&A surgery were included. Subjects with additional procedures were excluded. Mixed effects analyses were performed to identify variation in mean costs due to surgeon, hospital, and patient factors. Surgeons' mean cost/case was related to subsequent complications, defined as any unplanned visit within 21 days in the healthcare system. The study cohort included 26,626 T&As performed by 66 surgeons at 18 hospitals. Mean cost per T&A was $1,355 ± $505. Mixed effects analysis using patient factors as fixed effects and surgeon and hospital as a random effect identified significant variation in mean costs per surgeon, with 95% of surgeons having a mean cost/case between 67% and 150% of the overall mean (range, $874-$2,232/case). Similar variability was found among hospitals, with 95% of the facilities having mean costs between 64% to 156% of the mean (range, $1,029-$2,385/case). Severity of illness and several other patient factors exhibited small but statistically significant associations with cost. Surgeons' mean cost/case was moderately associated with an increased complication rate. Significant variation in same-day pediatric T&A surgery costs exists among different surgeons and hospitals within a multihospital network. Reducing variation in costs while maintaining outcomes may improve healthcare value and eliminate waste. 4. © 2014 The American Laryngological, Rhinological and Otological Society, Inc.

Black-White variations in the lagged reciprocal relationship between religiosity and perceived control.

PubMed

Oates, Gary

2013-06-01

This national longitudinal data-based multi-population LISREL study, the most comprehensive assessment to date of racial variations in the (in)congruity between religiosity and perceived control, gauges variation among Black and White Americans in the lagged reciprocal relationship between religiosity dimensions and mastery. Racial variation in the reciprocal religiosity-perceived control relationship has hitherto gone un-addressed. Prior investigations have also typically utilised cross-sectional samples - often from regional or age-specific populations. The observed public religiosity-mastery relationship over time exhibits signs of mutual reinforcement among Blacks: public religiosity enhances Blacks' subsequent mastery, while prior mastery borderline-significantly enhances their public religiosity. The subjective religiosity-mastery relationship among Whites evinces a marginally countervailing pattern: Subjective religiosity diminishes Whites' mastery, while mastery borderline-significantly enhances their subjective religiosity. The inordinately positive public religiosity-effect on Blacks' mastery notably constitutes solid support for the " resource compensation " perspective on the impact of religiosity on mastery across dominant and subordinate groups.

Variations in Global Precipitation: Climate-scale to Floods

NASA Technical Reports Server (NTRS)

Adler, Robert

2006-01-01

Variations in global precipitation from climate-scale to small scale are examined using satellite-based analyses of the Global Precipitation Climatology Project (GPCP) and information from the Tropical Rainfall Measuring Mission (TRMM). Global and large regional rainfall variations and possible long-term changes are examined using the 27- year (1979-2005) monthly dataset from the GPCP. In addition to global patterns associated with phenomena such as ENSO, the data set is explored for evidence of longterm change. Although the global change of precipitation in the data set is near zero, the data set does indicate a small upward trend in the Tropics (25S-25N), especially over ocean. Techniques are derived to isolate and eliminate variations due to ENS0 and major volcanic eruptions and the significance of the trend is examined. The status of TRMM estimates is examined in terms of evaluating and improving the long-term global data set. To look at rainfall variations on a much smaller scale TRMM data is used in combination with observations from other satellites to produce a 3-hr resolution, eight-year data set for examination of weather events and for practical applications such as detecting floods. Characteristics of the data set are presented and examples of recent flood events are examined.

Case mix adjusted variation in cesarean section rate in Sweden.

PubMed

Mesterton, Johan; Ladfors, Lars; Ekenberg Abreu, Anna; Lindgren, Peter; Saltvedt, Sissel; Weichselbraun, Marianne; Amer-Wåhlin, Isis

2017-05-01

Cesarean section (CS) rate is a well-established indicator of performance in maternity care and is also related to resource use. Case mix adjustment of CS rates when performing comparisons between hospitals is important. The objective of this study was to estimate case mix adjusted variation in CS rate between hospitals in Sweden. In total, 139 756 deliveries in 2011 and 2012 were identified in administrative systems in seven regions covering 67% of all deliveries in Sweden. Data were linked to the Medical birth register and population data. Twenty-three different sociodemographic and clinical characteristics were used for adjustment. Analyses were performed for the entire study population as well as for two subgroups. Logistic regression was used to analyze differences between hospitals. The overall CS rate was 16.9% (hospital minimum-maximum 12.1-22.6%). Significant variations in CS rate between hospitals were observed after case mix adjustment: hospital odds ratios for CS varied from 0.62 (95% CI 0.53-0.73) to 1.45 (95% CI 1.37-1.52). In nulliparous, cephalic, full-term, singletons the overall CS rate was 14.3% (hospital minimum-maximum: 9.0-19.0%), whereas it was 4.7% for multiparous, cephalic, full-term, singletons with no previous CS (hospital minimum-maximum: 3.2-6.7%). In both subgroups significant variations were observed in case mix adjusted CS rates. Significant differences in CS rate between Swedish hospitals were found after adjusting for differences in case mix. This indicates a potential for fewer interventions and lower resource use in Swedish childbirth care. Best practice sharing and continuous monitoring are important tools for improving childbirth care. © 2017 Nordic Federation of Societies of Obstetrics and Gynecology.

Circadian and seasonal variation of migraine attacks in children.

PubMed

Soriani, Stefano; Fiumana, Elisa; Manfredini, Roberto; Boari, Benedetta; Battistella, Pier Antonio; Canetta, Elisabetta; Pedretti, Stefania; Borgna-Pignatti, Caterina

2006-01-01

To investigate the rhythmicity of migraine episodes without aura in a pediatric population. Time of occurrence of 2517 migraine attacks in 115 children was recorded, by means of a diary, both by hourly and monthly intervals. A significant circadian variation, characterized by a peak in the afternoon (P < .001) and one in the early morning (P= .002) was found. A seasonal peak was also observed between November and January, while a nadir was observed in July. The clustering of attacks in the morning and midday and in autumn-winter, with a minimum frequency in July, suggests that school activities may represent an important cause of migraine.

Variation and evolution of male sex combs in Drosophila: nature of selection response and theories of genetic variation for sexual traits.

PubMed

Ahuja, Abha; Singh, Rama S

2008-05-01

We investigated the genetic architecture of variation in male sex comb bristle number, a rapidly evolving secondary sexual character of Drosophila. Twenty-four generations of divergent artificial selection for sex comb bristle number in a heterogeneous population of Drosophila melanogaster resulted in a significant response that was more pronounced in the direction of low bristle numbers. We observed a strong positive correlated response to selection in the corresponding female transverse bristle row. The correlated response in male abdominal and sternopleural bristle numbers, on the other hand, did not follow the same pattern as sex comb bristle number differences between selection lines. Relaxation-of-selection experiments along with mate choice and fecundity assays using the selection lines developed demonstrated the action of stabilizing selection on sex comb bristle number. Our results show (1) substantial genetic variation underlying sex comb bristle number variation; (2) a weak relationship between the sex comb and developmentally related, non-sex bristle systems; and (3) that sexual selection may be a driving force in sex comb evolution, indicating the potential of sex combs to diversify rapidly during population differentiation and speciation. We discuss the implications of these results for theories of genetic variation in display and nondisplay male sex traits.

Oceanographic variation influences spatial genomic structure in the sea scallop, Placopecten magellanicus.

PubMed

Van Wyngaarden, Mallory; Snelgrove, Paul V R; DiBacco, Claudio; Hamilton, Lorraine C; Rodríguez-Ezpeleta, Naiara; Zhan, Luyao; Beiko, Robert G; Bradbury, Ian R

2018-03-01

Environmental factors can influence diversity and population structure in marine species and accurate understanding of this influence can both improve fisheries management and help predict responses to environmental change. We used 7163 SNPs derived from restriction site-associated DNA sequencing genotyped in 245 individuals of the economically important sea scallop, Placopecten magellanicus , to evaluate the correlations between oceanographic variation and a previously identified latitudinal genomic cline. Sea scallops span a broad latitudinal area (>10 degrees), and we hypothesized that climatic variation significantly drives clinal trends in allele frequency. Using a large environmental dataset, including temperature, salinity, chlorophyll a, and nutrient concentrations, we identified a suite of SNPs (285-621, depending on analysis and environmental dataset) potentially under selection through correlations with environmental variation. Principal components analysis of different outlier SNPs and environmental datasets revealed similar northern and southern clusters, with significant associations between the first axes of each ( R 2 adj  = .66-.79). Multivariate redundancy analysis of outlier SNPs and the environmental principal components indicated that environmental factors explained more than 32% of the variance. Similarly, multiple linear regressions and random-forest analysis identified winter average and minimum ocean temperatures as significant parameters in the link between genetic and environmental variation. This work indicates that oceanographic variation is associated with the observed genomic cline in this species and that seasonal periods of extreme cold may restrict gene flow along a latitudinal gradient in this marine benthic bivalve. Incorporating this finding into management may improve accuracy of management strategies and future predictions.

Are solar brightness variations faculae- or spot-dominated?

NASA Astrophysics Data System (ADS)

Shapiro, A. I.; Solanki, S. K.; Krivova, N. A.; Yeo, K. L.; Schmutz, W. K.

2016-05-01

Context. Regular spaceborne measurements have revealed that solar brightness varies on multiple timescales, variations on timescales greater than a day being attributed to a surface magnetic field. Independently, ground-based and spaceborne measurements suggest that Sun-like stars show a similar, but significantly broader pattern of photometric variability. Aims: To understand whether the broader pattern of stellar variations is consistent with the solar paradigm, we assess relative contributions of faculae and spots to solar magnetically-driven brightness variability. We investigate how the solar brightness variability and its facular and spot contributions depend on the wavelength, timescale of variability, and position of the observer relative to the ecliptic plane. Methods: We performed calculations with the SATIRE model, which returns solar brightness with daily cadence from solar disc area coverages of various magnetic features. We took coverages as seen by an Earth-based observer from full-disc SoHO/MDI and SDO/HMI data and projected them to mimic out-of-ecliptic viewing by an appropriate transformation. Results: Moving the observer away from the ecliptic plane increases the amplitude of 11-year variability as it would be seen in Strömgren (b + y)/2 photometry, but decreases the amplitude of the rotational brightness variations as it would appear in Kepler and CoRoT passbands. The spot and facular contributions to the 11-year solar variability in the Strömgren (b + y)/2 photometry almost fully compensate each other so that the Sun appears anomalously quiet with respect to its stellar cohort. Such a compensation does not occur on the rotational timescale. Conclusions: The rotational solar brightness variability as it would appear in the Kepler and CoRoT passbands from the ecliptic plane is spot-dominated, but the relative contribution of faculae increases for out-of-ecliptic viewing so that the apparent brightness variations are faculae-dominated for

Variations in Gegenschein polarization

NASA Technical Reports Server (NTRS)

Sparrow, J. G.; Weinberg, J. L.

1975-01-01

Claims made by Bandermann and Wolstencroft (1974) that angular structure and day-to-day variations of the polarized component of the zodiacal light were observed near the antisolar point are shown to be unsubstantiated. The data obtained by Bandermann and Wolstencroft are reviewed together with the instruments they used. It is shown that the incorrect results reported were due to observation errors.

[Clinical and pathological significance of carotid siphon calcification observed on bone condition of brain CT].

PubMed

Matsumoto, Hideyuki; Hamaguchi, Hirotoshi; Nakayama, Takahiro; Oda, Tetsuya; Ikagawa, Takashi; Imafuku, Ichiro

2008-02-01

On plain brain computed tomography (CT), it is difficult to evaluate stenosis of internal carotid artery (ICA) because ICA is surrounded by structures, even though we can observe calcification of carotid siphon in some patients by using bone condition. However the pathologic significance has not been well known. We studied the pathologic significance of carotid siphon calcification observed on bone condition of brain CT. A total of 112 patients who were diagnosed or suspected as cerebrovascular diseases were registered. We classified the calcification into four levels (none, mild, moderate, severe) based on the degree of calcification. Then we compared it with the degree of stenosis of carotid siphon seen on brain magnetic resonance angiography (MRA) and with max intima-medial thickness (IMT) from common carotid artery (CCA) to ICA on carotid ultrasonography. The mean +/- standard deviation of max IMT to none, mild, moderate and severe in the degree of calcification were 1.03 +/- 0.64 (0.4-2.8), 1.65 +/- 0.83 (0.5-4.1), 2.03 +/- 0.83 (0.8-4.1) and 2.81 +/- 1.15 (0.7-6.5) mm, respectively. The calcification on brain CT significantly correlated with the degree of stenosis on brain MRA and with max IMT on carotid ultrasonography. The calcification of carotid siphon on bone condition of brain CT correlated with stenosis of the same portion and atherosclerosis of CCA bifurcation. Recently, on DICOM viewer, clinicians can convert plain condition into bone condition on brain CT due to popularization of PACS. We should pay attention to calcification of carotid siphon in patients with ischemic cerebrovascular diseases because we can estimate the atherosclerosis of both carotid siphon and CCA bifurcation easily and immediately.

Anatomical variations of the deep head of Cruveilhier of the flexor pollicis brevis and its significance for the evolution of the precision grip

PubMed Central

Aziz, M. Ashraf

2017-01-01

Cruveilhier described in 1834 the human flexor pollicis brevis (FPB), a muscle of the thenar compartment, as having a superficial and a deep head, respectively, inserted onto the radial and ulnar sesamoids of the thumb. Since then, Cruveilhier’s deep head has been controversially discussed. Often this deep head is confused with Henle’s “interosseous palmaris volaris” or said to be a slip of the oblique adductor pollicis. In the 1960s, Day and Napier described anatomical variations of the insertions of Cruveilhier’s deep head, including its absence, and hypothesized, that the shift of the deep head’s insertion from ulnar to radial facilitated “true opposability” in anthropoids. Their general thesis for muscular arrangements underlying the power and precision grip is sound, but they did not delineate their deep head from Henle’s muscle or the adductor pollicis, and their description of the attachments of Cruveilhier’s deep head were too vague and not supported by a significant portion of the anatomical literature. Here, we reinvestigated Cruveilhier’s deep head to resolve the controversy about it and because many newer anatomy textbooks do not describe this muscle, while it is often an obvious functionally (writing, texting, precision grip) and clinically significant thenar muscle. For the first time, we empirically delineated Cruveilhier’s deep head from neighboring muscles with which it was previously confused. We observed 100% occurrence of the uncontested deep head in 80 human hands, displaying a similar variability of insertions as Day and Napier, but in significantly different numbers. Furthermore, we found variability in the origin and included as important landmarks the trapezoid and the ligamentum carpi radiatum. We tested the assertion regarding the evolutionary morphology and its role in the improvements in thumb movements during various precision grips. Our overall conclusions differ with respect to the developmental and

HVSR Response Evolution due to Seasonal Variation: Observations from 2 Years of Continuous Monitoring

NASA Astrophysics Data System (ADS)

Nurse, K. B.; Milkereit, B.

2017-12-01

The seismic Horizontal to Vertical Spectral Ratio analysis technique reliably gives overburden depth to bedrock, for an independently determined Vs, based on the frequency of the main resonance peak. Above this, smaller resonances reflect the velocity structure within the overburden itself. This range in the HVSR response shows sufficient sensitivity to be exploited as a monitoring tool, to detect change in seismic physical properties and from that, change in overburden conditions. To explore the variation of the response, several 3C geophones have been deployed in southern Ontario, Canada since December 2015 (and ongoing). The local geology is a sedimentary basin with 30m of overburden, a simple 2D environment well suited for the HVSR method. Data are collected for 15s per minute, with an effective frequency band of 2-400Hz. HVSR estimates are produced for each sampling period and archived. Over these two years, winter freeze/thaw, saturated spring and summer draught conditions were sampled. H/V daily averages are dominated by the stable 3Hz resonance due to the overall surface layer, but smaller spectral peaks up to 100Hz are clear and evolve in frequency and amplitude over the collection period. Ground freeze/thaw cycles are clearly evident by significant reduction in the horizontal field, but also the changing of the soil moisture content throughout the year causes subtle shifts in the response (correlated to rain events and water table variation). The long term sampling does show a sensitivity of the HVSR method to the overburden in proximity to the sensor, and suggests a possibility for its use in monitoring soil / water-table conditions. But it also highlights that the estimate from an isolated H/V acquisition does include this variability and needs to be adequately quantified in VS30 estimates.

Variation in the prevalence of chronic bronchitis among smokers: a cross-sectional study.

PubMed

Mahesh, P A; Jayaraj, B S; Chaya, S K; Lokesh, K S; McKay, A J; Prabhakar, A K; Pape, U J

2014-07-01

Given the wide variations in prevalence of chronic obstructive pulmonary disease observed between populations with similar levels of exposure to tobacco smoke, we aimed to investigate the possibility of variations in prevalence of chronic bronchitis (CB) between two geographically distinct smoking populations in rural Karnataka, India. The Burden of Obstructive Lung Disease (BOLD) questionnaire was administered to all men aged >30 years in a cross-sectional survey. The χ(2) and Fisher's exact tests were used to compare CB prevalence in the two populations. Logistic regression was used to analyse the impact of multiple variables on the occurrence of CB. Two samples of 2322 and 2182 subjects were included in the study. In non-smokers, CB prevalence did not differ between the populations. However, it was significantly different between smoking populations (44.79% vs. 2.13%, P < 0.0001). Logistic regression indicated that, in addition to smoking, region, age, occupational dust exposure and type of house were associated with higher likelihood of CB. An interaction between smoking and area of residence was found (P < 0.001) and appeared to explain the effect of region (without interaction). A significant difference in CB prevalence was observed between male populations from two areas of Karnataka state, including when stratified by smoking status. No significant difference was observed between non-smokers.

Asian couples in negotiation: a mixed-method observational study of cultural variations across five Asian regions.

PubMed

Lee, Wai-Yung; Nakamura, Shin-Ichi; Chung, Moon Ja; Chun, Young Ju; Fu, Meng; Liang, Shu-Chuan; Liu, Cui-Lian

2013-09-01

The purpose of this study was to explore variations in how contemporary couples from five different Asian regions negotiate disagreements. Video recordings of 50 couples (10 each from Japan, Korea, Mainland China, Taiwan, and Hong Kong) discussing unresolved disagreements provided raw data for quantitative and qualitative analyses. First, teams of coders from each region used a common protocol to make quantitative ratings of content themes and interaction patterns for couples from their own region. An interregional panel of investigators then performed in-depth qualitative reviews for half of these cases, noting cultural differences not only in observed patterns of couple behavior but also in their own perceptions of these patterns. Both quantitative and qualitative analyses revealed clear regional differences on dimensions such as overt negativity, demand-withdraw interaction, and collaboration. The qualitative results also provided a richer, more nuanced view of other (e.g., gender-linked) conflict management patterns that the quantitative analyses did not capture. Inconsistencies between qualitative and quantitative data and between the qualitative observations of investigators from different regions were most pronounced for couples from Korea and Japan, whose conflict styles were subtler and less direct than those of couples from the other regions. © FPI, Inc.

Systematic Regional Variations in Purkinje Cell Spiking Patterns

PubMed Central

Xiao, Jianqiang; Cerminara, Nadia L.; Kotsurovskyy, Yuriy; Aoki, Hanako; Burroughs, Amelia; Wise, Andrew K.; Luo, Yuanjun; Marshall, Sarah P.; Sugihara, Izumi; Apps, Richard; Lang, Eric J.

2014-01-01

In contrast to the uniform anatomy of the cerebellar cortex, molecular and physiological studies indicate that significant differences exist between cortical regions, suggesting that the spiking activity of Purkinje cells (PCs) in different regions could also show distinct characteristics. To investigate this possibility we obtained extracellular recordings from PCs in different zebrin bands in crus IIa and vermis lobules VIII and IX in anesthetized rats in order to compare PC firing characteristics between zebrin positive (Z+) and negative (Z−) bands. In addition, we analyzed recordings from PCs in the A2 and C1 zones of several lobules in the posterior lobe, which largely contain Z+ and Z− PCs, respectively. In both datasets significant differences in simple spike (SS) activity were observed between cortical regions. Specifically, Z− and C1 PCs had higher SS firing rates than Z+ and A2 PCs, respectively. The irregularity of SS firing (as assessed by measures of interspike interval distribution) was greater in Z+ bands in both absolute and relative terms. The results regarding systematic variations in complex spike (CS) activity were less consistent, suggesting that while real differences can exist, they may be sensitive to other factors than the cortical location of the PC. However, differences in the interactions between SSs and CSs, including the post-CS pause in SSs and post-pause modulation of SSs, were also consistently observed between bands. Similar, though less strong trends were observed in the zonal recordings. These systematic variations in spontaneous firing characteristics of PCs between zebrin bands in vivo, raises the possibility that fundamental differences in information encoding exist between cerebellar cortical regions. PMID:25144311

Heat flux variations over sea-ice observed at the coastal area of the Sejong Station, Antarctica

NASA Astrophysics Data System (ADS)

Park, S.; Choi, T.; Kim, S.

2012-12-01

This study presents variations of sensible heat flux and latent heat flux over sea-ice observed in 2011 from the 10-m flux tower located at the coast of the Sejong Station on King George Island, Antarctica. A period from June to November was divided into three parts: "Freezing", "Frozen", and "Melting" periods based on daily monitoring of sea state and hourly photos looking at the Marian Cove in front of the Sejong Station. The division of periods enabled us to look into the heat flux variations depending on the sea-ice conditions. Over freezing sea surface during the freezing period of late June, daily mean sensible heat flux was -11.9 Wm-2 and daily mean latent heat flux was +16.3 Wm-2. Over the frozen sea-ice, daily mean sensible heat flux was -10.4 Wm-2 while daily mean latent heat flux was +2.4 Wm-2. During the melting period of mid-October to early November, magnitudes of sensible heat flux increased to -14.2 Wm-2 and latent heat flux also increased to +13.5 Wm-2. In short, latent heat flux was usually upward over sea-ice most of the time while sensible heat flux was downward from atmosphere to sea-ice. Magnitudes of the fluxes were small but increased when freezing or melting of sea-ice was occurring. Especially, latent heat flux increased five to six times compared to that of "frozen" period implying that early melting of sea-ice may cause five to six times larger supply of moisture to the atmosphere.

Abundance Variations and Flows in Plage Regions Observed with CDS/SOHO

NASA Astrophysics Data System (ADS)

Rank, G.; Bagalá, L. G.; Czaykowska, A.; Haerendel, G.

1999-10-01

We present results from CDS/SOHO observations of the spotless active region NOAA-8208, obtained on 28th April 1998 near disk center. MDI images show a bipolar magnetic configuration. The regions of enhanced He I emission correspond to the areas with strong magnetic flux and also with bright plage areas seen in Ca II and H-alpha images. A high correlation is found between intensity maps of the transition region lines He I (logTmax = 4.3), O III (logTmax = 5.0), and O V (logTmax = 5.4). The line-of-sight velocities of He I reveal a strong downflow in the plage areas. Further, the line-of-sight velocities of He I, O III, and O V are well correlated, showing that the downflow pattern exists up to temperatures of about 0.25 MK. At higher temperatures (Mg VIII at logTmax = 5.8) this flow is not detected, suggesting that material streams into the plage region from sideways in the high transition region. Maps of the electron density in the transition region have been constructed from several line ratios yielding densities of about 9.0 cm-3 in the plage regions, about dex 0.5 cm-3 higher compared to the surrounding. To study the spatial variation of the first ionization potential (FIP) effect, the abundance ratio has been mapped for the ion ratio MgVI/NeVI. The ratio is highly variable on spatial scales down to a few arcsec from photospheric values to enhancements of a factor of 10. The strongest FIP enhancements are not correlated with transition region line emission, but are found outside of the plage regions. Some areas of strong FIP enhancement appear stretched and elongated, suggesting that the material is confined in loop-like structures.

Line Bisector Variations in Stars with Extrasolar Planets

NASA Astrophysics Data System (ADS)

Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman, T.

1999-12-01

We present the results from a high-resolution, synoptic spectroscopic program of observation of ten F- and G-type stars, seven of which exhibit periodic radial velocity variations attributed to the presence of one or more substellar companions. The observations were obtained from 1998 March to 1999 February using the 1.52-m NSO McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction with the solar-stellar spectrograph. The spectra were acquired with a resolving power of approximately 1.2 x 105. The line bisector was then derived from unblended photospheric features. In particular, we define the velocity displacement of the spectral line bisector and determine the bisector amplitude for the Fe I absorption line at 625.26 nm in order to search for variations in the line asymmetry over time. Such variations could mimic Doppler shifts in observations with lower spectral resolution. Examination of the bisector velocity displacement over the time span of our observations reveals no substantial difference between stars with planetary companions and those without reported companions. We find no correlation between the bisector variations and the orbital phase of a substellar companion in any of our target stars. Simulations of a periodic signal with noise levels based on our measurement errors suggest that we can exclude bisector variations with amplitudes greater than about 20 m s-1. These results support the conclusion that extrasolar planets best explain the observed periodic variations in radial velocity. This work was supported by a NASA grant to the NOAO under the auspices of the Origins of Solar Systems Program. MP gratefully acknowledges support from the NSF-sponsored Research Experience for Undergraduates (REU) program at the NOAO. The NOAO is operated by AURA, Inc., under a cooperative agreement with the NSF.

Spatial distribution and temporal variations of occurrence frequency of lightning whistlers observed by VLF/WBA onboard Akebono

NASA Astrophysics Data System (ADS)

Oike, Yuta; Kasahara, Yoshiya; Goto, Yoshitaka

2014-09-01

We statistically analyzed lightning whistlers detected from the analog waveform data below 15 kHz observed by the VLF instruments onboard Akebono. We examined the large amount of data obtained at Uchinoura Space Center in Japan for 22 years from 1989 to 2010. The lightning whistlers were mainly observed inside the L shell region below 2. Seasonal dependence of the occurrence frequency of lightning whistlers has two peaks around July to August and December to January. As lightning is most active in summer, in general, these two peaks correspond to summer in the Northern and Southern Hemispheres, respectively. Diurnal variation of the occurrence frequency showed that lightning whistlers begin to increase in the early evening and remain at a high-occurrence level through the night with a peak around 21 in magnetic local time (MLT). This peak shifts toward nightside compared with lightning activity, which begins to rise around noon and peaks in the late afternoon. This trend is supposed to be caused by attenuation of VLF wave in the ionosphere in the daytime. Comparison study with the ground-based observation revealed consistent results, except that the peak of the ground-based observation appeared after midnight while our measurements obtained by Akebono was around 21 in MLT. This difference is explained qualitatively in terms that lightning whistlers measured at the ground station passed through the ionosphere twice above both source region and the ground station. These facts provide an important clue to evaluate quantitatively the absorption effect of lightning whistler in the ionosphere.

Investigating the variation of terrestrial water storage under changing climate and land cover

NASA Astrophysics Data System (ADS)

Fang, Y.; Niu, G. Y.; Zhang, X.; Troch, P. A. A.

2015-12-01

Terrestrial water storage (TWS) consists of groundwater, soil moisture, snow and ice, lakes and rivers and water contained in biomass. The water storage, especially the subsurface storage, is an essential property of the catchment, which controls climate, hydrological and biogeochemical processes at different scales. During the past decades, climate and land cover change has been proved to exert significant influences on hydrological processes which in turn alters the TWS variation. In order to better understand the interaction and feedback mechanism between TWS and earth system, it is necessary to quantify the effects of climate and land cover change on TWS variation. Direct estimation of total TWS has been made possible by the Gravity Recovery And Climate Experiment (GRACE) satellites that measures the earth gravity field. At present, few efforts were made to explicitly investigate the TWS variation under changing climate and land cover. GRACE data has its own limitations. One is its temporal coverage is short, it's only available since 2002, which is not sufficient to reflect the trend due to climate and land cover change. The other reason is that it cannot distinguish different components contributing to TWS. The limitation of TWS observation data can be overcame by numerical models developed to reproduce or to predict different earth system processes. After calibration and validation, with limited observations, these models can be trusted to extend our knowledge to where observations are not available both in time and space. In this study, based on Noah-MP LSM and satellite and ground data, we aim to: (1) Investigate the variation of total TWS as well as its components over Upper Colorado River Basin from 1990 to 2014. (2) Identify the major factors that control the TWS variation. (3) Quantify how the changing climate and land cover affect TWS variation in the same period.

Spatiotemporal Variations in the Difference between Satellite-observed Land Surface Temperature and Station-based Near-surface Air Temperature

NASA Astrophysics Data System (ADS)

Lian, X.

2016-12-01

There is an increasing demand to integrate land surface temperature (LST) into climate research due to its global coverage, which requires a comprehensive knowledge of its distinctive characteristics compared to near-surface air temperature ( ). Using satellite observations and in-situ station-based datasets, we conducted a global-scale assessment of the spatial, seasonal, and interannual variations in the difference between daytime maximum LST and daytime maximum ( , LST - ) during 2003-2014. Spatially, LST is generally higher than over arid and sparsely vegetated regions in the mid-low latitudes, but LST is lower than in the tropical rainforests due to strong evaporative cooling, and in the high-latitude regions due to snow-induced radiative cooling. Seasonally, is negative in tropical regions throughout the year, while it displays a pronounced seasonality in both the mid-latitudes and boreal regions. The seasonality in the mid-latitudes is a result of the asynchronous responses of LST and to the seasonal cycle of radiation and vegetation abundance, whereas in the boreal regions, seasonality is mainly caused by the change in snow cover. At an interannual scale, only a small proportion of the land surface displays a statistically significant trend (P <0.05) due to the short time span of current measurements. Our study identified substantial spatial heterogeneity and seasonality in , as well as its determinant environmental drivers, and thus provides a useful reference for monitoring near-surface temperature changes using remote sensing, particularly in remote regions.

Total solar eclipse effects on VLF signals: Observations and modeling

NASA Astrophysics Data System (ADS)

Clilverd, Mark A.; Rodger, Craig J.; Thomson, Neil R.; Lichtenberger, János; Steinbach, Péter; Cannon, Paul; Angling, Matthew J.

During the total solar eclipse observed in Europe on August 11, 1999, measurements were made of the amplitude and phase of four VLF transmitters in the frequency range 16-24 kHz. Five receiver sites were set up, and significant variations in phase and amplitude are reported for 17 paths, more than any previously during an eclipse. Distances from transmitter to receiver ranged from 90 to 14,510 km, although the majority were <2000 km. Typically, positive amplitude changes were observed throughout the whole eclipse period on path lengths <2000 km, while negative amplitude changes were observed on paths >10,000 km. Negative phase changes were observed on most paths, independent of path length. Although there was significant variation from path to path, the typical changes observed were ~3 dB and ~50°. The changes observed were modeled using the Long Wave Propagation Capability waveguide code. Maximum eclipse effects occurred when the Wait inverse scale height parameter β was 0.5 km-1 and the effective ionospheric height parameter H' was 79 km, compared with β=0.43km-1 and H'=71km for normal daytime conditions. The resulting changes in modeled amplitude and phase show good agreement with the majority of the observations. The modeling undertaken provides an interpretation of why previous estimates of height change during eclipses have shown such a range of values. A D region gas-chemistry model was compared with electron concentration estimates inferred from the observations made during the solar eclipse. Quiet-day H' and β parameters were used to define the initial ionospheric profile. The gas-chemistry model was then driven only by eclipse-related solar radiation levels. The calculated electron concentration values at 77 km altitude throughout the period of the solar eclipse show good agreement with the values determined from observations at all times, which suggests that a linear variation in electron production rate with solar ionizing radiation is reasonable

Habitat-Specific Morphological Variation among Threespine Sticklebacks (Gasterosteus aculeatus) within a Drainage Basin

PubMed Central

Webster, Mike M.; Atton, Nicola; Hart, Paul J. B.; Ward, Ashley J. W.

2011-01-01

Habitat-specific morphological variation, often corresponding to resource specialization, is well documented in freshwater fishes. In this study we used landmark based morphometric analyses to investigate morphological variation among threespine sticklebacks (Gasterosteus aculeatus L.) from four interconnected habitat types within a single lowland drainage basin in eastern England. These included the upper and lower reaches of the river, the estuary, a connected ditch network and a coastal salt marsh. We found significant habitat-specific differences in morphology, with three axes of variation describing differences in orbit diameter, body depth, caudal peduncle shape and pectoral fin positioning as well as variation in relative dorsal and pelvic spine size. Interestingly, the ditch system, an artificial and heavily managed habitat, is populated by sticklebacks with a characteristic morphology, suggesting that human management of habitats can in some circumstances lead to morphological variation among the animals that inhabit them. We discuss the mechanisms that conceivably underlie the observed morphological variation and the further work necessary to identify them. Finally, we consider the implications of habitat-specific body shape variation for the behavioural ecology of this ecologically generalist species. PMID:21698269

"They Have to Adapt to Learn": Surgeons' Perspectives on the Role of Procedural Variation in Surgical Education.

PubMed

Apramian, Tavis; Cristancho, Sayra; Watling, Chris; Ott, Michael; Lingard, Lorelei

2016-01-01

Clinical research increasingly acknowledges the existence of significant procedural variation in surgical practice. This study explored surgeons' perspectives regarding the influence of intersurgeon procedural variation on the teaching and learning of surgical residents. This qualitative study used a grounded theory-based analysis of observational and interview data. Observational data were collected in 3 tertiary care teaching hospitals in Ontario, Canada. Semistructured interviews explored potential procedural variations arising during the observations and prompts from an iteratively refined guide. Ongoing data analysis refined the theoretical framework and informed data collection strategies, as prescribed by the iterative nature of grounded theory research. Our sample included 99 hours of observation across 45 cases with 14 surgeons. Semistructured, audio-recorded interviews (n = 14) occurred immediately following observational periods. Surgeons endorsed the use of intersurgeon procedural variations to teach residents about adapting to the complexity of surgical practice and the norms of surgical culture. Surgeons suggested that residents' efforts to identify thresholds of principle and preference are crucial to professional development. Principles that emerged from the study included the following: (1) knowing what comes next, (2) choosing the right plane, (3) handling tissue appropriately, (4) recognizing the abnormal, and (5) making safe progress. Surgeons suggested that learning to follow these principles while maintaining key aspects of surgical culture, like autonomy and individuality, are important social processes in surgical education. Acknowledging intersurgeon variation has important implications for curriculum development and workplace-based assessment in surgical education. Adapting to intersurgeon procedural variations may foster versatility in surgical residents. However, the existence of procedural variations and their active use in surgeons

Antarctic meteor observations using the Davis MST and meteor radars

NASA Astrophysics Data System (ADS)

Holdsworth, David A.; Murphy, Damian J.; Reid, Iain M.; Morris, Ray J.

2008-07-01

This paper presents the meteor observations obtained using two radars installed at Davis (68.6°S, 78.0°E), Antarctica. The Davis MST radar was installed primarily for observation of polar mesosphere summer echoes, with additional transmit and receive antennas installed to allow all-sky interferometric meteor radar observations. The Davis meteor radar performs dedicated all-sky interferometric meteor radar observations. The annual count rate variation for both radars peaks in mid-summer and minimizes in early Spring. The height distribution shows significant annual variation, with minimum (maximum) peak heights and maximum (minimum) height widths in early Spring (mid-summer). Although the meteor radar count rate and height distribution variations are consistent with a similar frequency meteor radar operating at Andenes (69.3°N), the peak heights show a much larger variation than at Andenes, while the count rate maximum-to-minimum ratios show a much smaller variation. Investigation of the effects of the temporal sampling parameters suggests that these differences are consistent with the different temporal sampling strategies used by the Davis and Andenes meteor radars. The new radiant mapping procedure of [Jones, J., Jones, W., Meteor radiant activity mapping using single-station radar observations, Mon. Not. R. Astron. Soc., 367(3), 1050-1056, doi: 10.1111/j.1365-2966.2006.10025.x, 2006] is investigated. The technique is used to detect the Southern delta-Aquarid meteor shower, and a previously unknown weak shower. Meteoroid speeds obtained using the Fresnel transform are presented. The diurnal, annual, and height variation of meteoroid speeds are presented, with the results found to be consistent with those obtained using specular meteor radars. Meteoroid speed estimates for echoes identified as Southern delta-Aquarid and Sextantid meteor candidates show good agreement with the theoretical pre-atmospheric speeds of these showers (41 km s -1 and 32 km s -1

The affect of tissue depth variation on craniofacial reconstructions.

PubMed

Starbuck, John M; Ward, Richard E

2007-10-25

We examined the affect of tissue depth variation on the reconstruction of facial form, through the application of the American method, utilizing published tissue depth measurements for emaciated, normal, and obese faces. In this preliminary study, three reconstructions were created on reproductions of the same skull for each set of tissue depth measurements. The resulting morphological variation was measured quantitatively using the anthropometric craniofacial variability index (CVI). This method employs 16 standard craniofacial anthropometric measurements and the results reflect "pattern variation" or facial harmony. We report no appreciable variation in the quantitative measure of the pattern facial form obtained from the three different sets of tissue depths. Facial similarity was assessed qualitatively utilizing surveys of photographs of the three reconstructions. Surveys indicated that subjects frequently perceived the reconstructions as representing different individuals. This disagreement indicates that size of the face may blind observers to similarities in facial form. This research is significant because it illustrates the confounding effect that normal human variation contributes in the successful recognition of individuals from a representational three-dimensional facial reconstruction. Research results suggest that successful identification could be increased if multiple reconstructions were created which reflect a wide range of possible outcomes for facial form. The creation of multiple facial images, from a single skull, will be facilitated as computerized versions of facial reconstruction are further developed and refined.

Genetic Variation in the Nuclear and Organellar Genomes Modulates Stochastic Variation in the Metabolome, Growth, and Defense

PubMed Central

Joseph, Bindu; Corwin, Jason A.; Kliebenstein, Daniel J.

2015-01-01

Recent studies are starting to show that genetic control over stochastic variation is a key evolutionary solution of single celled organisms in the face of unpredictable environments. This has been expanded to show that genetic variation can alter stochastic variation in transcriptional processes within multi-cellular eukaryotes. However, little is known about how genetic diversity can control stochastic variation within more non-cell autonomous phenotypes. Using an Arabidopsis reciprocal RIL population, we showed that there is significant genetic diversity influencing stochastic variation in the plant metabolome, defense chemistry, and growth. This genetic diversity included loci specific for the stochastic variation of each phenotypic class that did not affect the other phenotypic classes or the average phenotype. This suggests that the organism's networks are established so that noise can exist in one phenotypic level like metabolism and not permeate up or down to different phenotypic levels. Further, the genomic variation within the plastid and mitochondria also had significant effects on the stochastic variation of all phenotypic classes. The genetic influence over stochastic variation within the metabolome was highly metabolite specific, with neighboring metabolites in the same metabolic pathway frequently showing different levels of noise. As expected from bet-hedging theory, there was more genetic diversity and a wider range of stochastic variation for defense chemistry than found for primary metabolism. Thus, it is possible to begin dissecting the stochastic variation of whole organismal phenotypes in multi-cellular organisms. Further, there are loci that modulate stochastic variation at different phenotypic levels. Finding the identity of these genes will be key to developing complete models linking genotype to phenotype. PMID:25569687

Genetic variation in the nuclear and organellar genomes modulates stochastic variation in the metabolome, growth, and defense.

PubMed

Joseph, Bindu; Corwin, Jason A; Kliebenstein, Daniel J

2015-01-01

Recent studies are starting to show that genetic control over stochastic variation is a key evolutionary solution of single celled organisms in the face of unpredictable environments. This has been expanded to show that genetic variation can alter stochastic variation in transcriptional processes within multi-cellular eukaryotes. However, little is known about how genetic diversity can control stochastic variation within more non-cell autonomous phenotypes. Using an Arabidopsis reciprocal RIL population, we showed that there is significant genetic diversity influencing stochastic variation in the plant metabolome, defense chemistry, and growth. This genetic diversity included loci specific for the stochastic variation of each phenotypic class that did not affect the other phenotypic classes or the average phenotype. This suggests that the organism's networks are established so that noise can exist in one phenotypic level like metabolism and not permeate up or down to different phenotypic levels. Further, the genomic variation within the plastid and mitochondria also had significant effects on the stochastic variation of all phenotypic classes. The genetic influence over stochastic variation within the metabolome was highly metabolite specific, with neighboring metabolites in the same metabolic pathway frequently showing different levels of noise. As expected from bet-hedging theory, there was more genetic diversity and a wider range of stochastic variation for defense chemistry than found for primary metabolism. Thus, it is possible to begin dissecting the stochastic variation of whole organismal phenotypes in multi-cellular organisms. Further, there are loci that modulate stochastic variation at different phenotypic levels. Finding the identity of these genes will be key to developing complete models linking genotype to phenotype.

Temporal variations of the anomalous oxygen component

NASA Technical Reports Server (NTRS)

Cummings, A. C.; Webber, W. R.

1983-01-01

Data from the cosmic ray experiment on Voyagers 1 and 2 was used to examine anomalous oxygen in the time period from launch in 1977 to the end of 1981. Several time periods were found where large periodic (typically 26 day) temporal variations of the oxygen intensity between approximately 5 - 15 MeV/nuc are present. Variations in intensity by up to a factor of 10 are observed during these periods. Several characteristics of these variations indicate that they are not higher energy extensions of the low energy particle (approximately 1 MeV/nuc) increases found in many corotating interaction regions (CIR's). Many of these periodic temporal variations are correlated with similar, but much smaller, recurrent variations in the 75 MeV proton rate. Voyager 1 and Voyager 2 counting rates were compared to estimate the local radial gradient for both the protons and the oxygen. The proton gradients during periods of both maximum and minumum fluxes are consistent with the overall positive radial gradients reported by others from Pioneer and near-Earth observations, supporting the view that these variations are due to local modulation of a source outside the radial range of project measurements. In contrast, the oxygen gradients during periods of maximum proton flux differ in sign from those during minimum proton fluxes, suggesting that the origin of the oxygen variations is different from that of the protons.

Spatial and Temporal Variations in Titan's Surface Temperatures from Cassini CIRS Observations