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Sample records for dependent hatching rates

  1. [Effect of different ecological factors on ricefield eel (Monopterus albus) hatching rate].

    PubMed

    Yin, Shaowu; Zhou, Gongjian; Liu, Yun

    2004-04-01

    This paper studied the effects, of some ecological factors (temperature, pH, hatching method and ammonia) on the embryonic development of ricefield eel. The results indicated that the optimum hatching temperature of ricefield eel was 25-28 degrees C, and no significant difference was found about the effects of pH within the range of pH 5.5-9.5 on the hatching rate of oosperm. Dripping water incubation had a higher hatching rate of oosperm than staticing water incubation, and the hatching rate of oosperm decreased with increasing ammonia content. The present study provided an available suggestion for the all-artificial and half-artificial breeding of ricefield eel. PMID:15334981

  2. The relationship between hatching rate and number of embryos of the brood pouch in Littorina saxatilis

    NASA Astrophysics Data System (ADS)

    Conde-Padín, P.; Carballo, M.; Caballero, A.; Rolán-Alvarez, E.

    2008-10-01

    Littorina saxatilis is an ovoviviparous organism in which shelled embryos can be directly observed in nearly all mature females captured in the wild. This characteristic has been used a number of times as an indirect estimate for fecundity of natural populations. However, there is no experimental corroboration that the number of embryos within a female brood pouch is actually related to the rate of hatching per unit of time, a more realistic estimate of female fecundity. In order to make this corroboration we estimated the correlation between the number of embryos in the brood pouch and the hatching rate of isolated females grown in the laboratory. We also compared the hatching rates of females from two sympatric ecotypes (RB and SU) of this species, which differ significantly in the number of embryos. We found a high agreement between hatching rate and number of embryos, concluding that the latter is a good proxy for fecundity.

  3. Embryonic Development and Rates of Metabolic Activity in Early and Late Hatching Eggs of the Major Malaria Vector Anopheles gambiae

    PubMed Central

    Kaiser, Maria L.; Duncan, Frances D.; Brooke, Basil D.

    2014-01-01

    Anopheles gambiae eggs generally hatch at the completion of embryo development; two-three days post oviposition. However, staggered or delayed hatching has been observed whereby a single batch of eggs shows marked variation in time-to-hatch, with some eggs hatching 18 days post oviposition or later. The mechanism enabling delayed hatch has not been clearly elucidated but is likely mediated by environmental and genetic factors that either induce diapause or slow embryo development. This study aimed to compare metabolic activity and embryonic development between eggs collected from sub-colonies of the baseline Anopheles gambiae GAH colony previously selected for early or late time-to-hatch. Egg batches from early and late hatch sub-colonies as well as from the baseline colony were monitored for hatching. For both time-to-hatch selected sub-colonies and the baseline colony the majority of eggs hatched on day two post oviposition. Nevertheless, eggs produced by the late hatch sub-colony showed a significantly longer mean time to hatch than those produced by the early hatch sub-colony. The overall proportions that hatched were similar for all egg batches. CO2 output between eggs from early and late hatch sub-colonies showed significant differences only at 3 and 7 days post oviposition where eggs from the early hatch and the late hatch sub-colony were more metabolically active, respectively. No qualitative differences were observed in embryo development between the sub-colonies. It is concluded that all viable embryos develop to maturity at the same rate and that a small proportion then enter a state of diapause enabling them to hatch later. As it has previously been shown that it is possible to at least partially select for late hatch, this characteristic is likely to involve genetic as well as environmental factors. Delayed hatching in An. gambiae is likely an adaptation to maximise reproductive output despite the increased risk of desiccation in an unstable aquatic

  4. Hatch success and temperature-dependent development time in two broadly distributed topminnows (Fundulidae)

    NASA Astrophysics Data System (ADS)

    Schaefer, Jacob

    2012-07-01

    Metabolic scaling laws predict a variety of emergent properties of biological systems based on relationships among temperature, body size, and rates of physiological processes. These models have been criticized as being overly simplistic and not accounting for directional variability arising from evolutionary tradeoffs. I measured hatch success and egg development time at six temperatures for 12 populations throughout the latitudinal range of two broadly distributed topminnows ( Fundulus). I asked if hatch success and development time differed between the species and northern and southern populations. Hatch success reaction norms suggested that the more broadly (and northern) distributed Fundulus notatus was more eurythermic with a lower optima and broader performance breadth than Fundulus olivaceus. Temperature explained most variability in mass-corrected development time. Development time differed between the species, but not northern and southern populations. Deviations from predictions of universal scaling laws were most pronounced away from specie's thermal optima.

  5. Heart rates increase after hatching in two species of natricine snakes

    PubMed Central

    Aubret, Fabien

    2013-01-01

    Experimental studies have shown heart rates to decrease from embryo to hatchling stage in turtles, remain steady in skinks, and increase in birds. However, no snake species has been studied in this regard. I recorded heart rate evolution trajectories from embryo to juvenile stage in 78 eggs from two species of European Natricine snakes. Unexpectedly, snakes behaved more like birds than turtles or lizards: heart rates increased after hatching in both N. maura and N. natrix, respectively by 43.92 ± 22.84% and 35.92 ± 24.52%. Heart rate shift was not related to an abrupt elevation of metabolism per se (snakes that increased their heart rates the most sharply grew the least after birth), but rather due to a number of smaller eggs that experienced lower than normal heart rates throughout the incubation and recovered a normal heart rate post-birth. This finding is discussed in the light of hatching synchrony benefits. PMID:24287712

  6. Interactions between hatch dates, growth rates, and mortality of Age-0 native Rainbow Smelt and nonnative Alewife in Lake Champlain

    USGS Publications Warehouse

    Parrish, Donna; Simonin, Paul W.; Rudstam, Lars G.; Pientka, Bernard; Sullivan, Patrick J.

    2016-01-01

    Timing of hatch in fish populations can be critical for first-year survival and, therefore, year-class strength and subsequent species interactions. We compared hatch timing, growth rates, and subsequent mortality of age-0 Rainbow Smelt Osmerus mordax and Alewife Alosa pseudoharengus, two common open-water fish species of northern North America. In our study site, Lake Champlain, Rainbow Smelt hatched (beginning May 26) almost a month earlier than Alewives (June 20). Abundance in the sampling area was highest in July for age-0 Rainbow Smelt and August for age-0 Alewives. Late-hatching individuals of both species grew faster than those hatching earlier (0.6 mm/d versus 0.4 for Rainbow Smelt; 0.7 mm/d versus 0.6 for Alewives). Mean mortality rate during the first 45 d of life was 3.4%/d for age-0 Rainbow Smelt and was 5.5%/d for age-0 Alewives. Alewife mortality rates did not differ with hatch timing but daily mortality rates of Rainbow Smelt were highest for early-hatching fish. Cannibalism is probably the primary mortality source for age-0 Rainbow Smelt in this lake. Therefore, hatching earlier may not be advantageous because the overlap of adult and age-0 Rainbow Smelt is highest earlier in the season. However, Alewives, first documented in Lake Champlain in 2003, may increase the mortality of age-0 Rainbow Smelt in the summer, which should favor selection for earlier hatching.

  7. Heart Rate Responses to Unaided Orion Side Hatch Egress in the Neutral Buoyancy Laboratory

    NASA Technical Reports Server (NTRS)

    English, Kirk L.; Hwang Emma Y.; Ryder, Jeffrey W.; Kelly, Cody; Walker, Thomas; Ploutz-Snyder, Lori L.

    2016-01-01

    NASA is developing the Orion capsule as a vehicle for transporting crewmembers to and from the International Space Station (ISS) and for future human space exploration missions. Orion and other commercial vehicles are designed to splash down in the ocean where nominally support personnel will assist crewmembers in egressing the vehicle. However, off-nominal scenarios will require crewmembers to egress the vehicle unaided, deploy survival equipment, and ingress a life raft. PURPOSE: To determine the heart rate (HR) responses to unaided Orion side hatch egress and raft ingress as a part of the NASA Crew Survival Engineering Team's evaluation of the PORT Orion mockup in the Neutral Buoyancy Laboratory (NBL). METHODS: Nineteen test subjects, including four astronauts (N=19, 14 males/5 females, 38.6+/-8.4 y, 174.4+/-9.6 cm, 75.7+/-13.1 kg), completed a graded maximal test on a cycle ergometer to determine VO2peak and HRpeak and were divided into five crews of four members each; one subject served on two crews. Each crew was required to deploy a life raft, egress the Orion vehicle from the side hatch, and ingress the life raft with two 8 kg emergency packs per crew. Each crew performed this activity one to three times; a total of ten full egresses were completed. Subjects wore a suit that was similar in form, mass, and function to the Modified Advanced Crew Escape Suit (MACES) including helmet, gloves, boots, supplemental O2 bottles, and a CO2-inflated life preserver (approx.18 kg); subjects began each trial seated supine in the PORT Orion mockup with seat belts and mockup O2 and communication connections and ended each trial with all four crewmembers inside the life raft. RESULTS: VO2peak was 40.8+/-6.8 mL/kg/min (3.1+/-0.7 L/min); HRpeak was 181+/-10 bpm. Total egress time across trials was 5.0+/-1.6 min (range: 2.8-8.0 min); all subjects were able to successfully complete all trials. Average maximum HR at activity start, at the hatch opening, in the water, and in the

  8. Heart Rate Responses to Unaided Orion Side Hatch Egress in the Neutral Buoyancy Laboratory

    NASA Technical Reports Server (NTRS)

    English, Kirk L.; Hwang, Emma Y.; Ryder, Jeffrey W.; Kelly, Cody; Walker, Thomas; Ploutz-Snyder, Lori

    2016-01-01

    The Orion capsule will be the next NASA-built vehicle used for near and deep space exploration. The nominal landing scenario for Orion involves splashdown in the Pacific Ocean and subsequent aided crew egress conducted by military personnel. Contingency operations, however, require the crew to egress the capsule unaided, deploy an inflatable life raft, and to ingress the raft. Unaided egress is expected to be physiologically demanding, but no data exist to corroborate this. Thus, we evaluated the heart rate response to unaided Orion side hatch egress and raft ingress as par of the NASA crew Survival Engineering Team's evaluation of egress procedures using the Post-landing Orion Recovery Trainer (PORT) article in the Neutral Buoyancy Laboratory (NBL).

  9. Maternal Vibration: An Important Cue for Embryo Hatching in a Subsocial Shield Bug

    PubMed Central

    Mukai, Hiromi; Hironaka, Mantaro; Tojo, Sumio; Nomakuchi, Shintaro

    2014-01-01

    Hatching care has been reported for many taxonomic groups, from invertebrates to vertebrates. The sophisticated care that occurs around hatching time is expected to have an adaptive function supporting the feeble young. However, details of the characteristics of the adaptive function of hatching care remain unclear. This study investigated the hatching care of the subsocial shield bug, Parastrachia japonensis (Heteroptera: Parastrachiidae) to verify its function. Results show that the P. japonensis mothers vibrated the egg mass intermittently while maintaining an egg-guarding posture. Then embryos started to emerge from their shells synchronously. Unlike such behaviors of closely related species, this vibrating behavior was faint, but lasted more than 6 h. To investigate the effect of this behavior on hatching synchrony and hatching success, we observed the hatching pattern and the hatching rate in control, mother-removed, and two artificial vibration groups. Control broods experienced continuous guarding from the mother. Intermittent artificial vibration broods were exposed to vibrations that matched the temporal pattern of maternal vibration produced by a motor. They showed synchronous hatching patterns and high hatching rates. However, for mother-removed broods, which were isolated from the mother, and when we provided continuous artificial vibration that did not match the temporal pattern of the maternal vibration, embryo hatching was not only asynchronous: some embryos failed to emerge from their shells. These results lead us to infer that hatching care in P. japonensis has two functions: hatching regulation and hatching assistance. Nevertheless, several points of observational and circumstantial evidence clearly contraindicate hatching assistance. A reduction in the hatching rate might result from dependence on maternal hatching care as a strong cue in P. japonensis. We conclude that the hatching care of P. japonensis regulates the hatching pattern and serves

  10. Hatch rate of channel catfish Ictalurus punctatus (Rafinesque 1818) eggs treated with 100 mg L-1 copper sulphate pentahydrate. Aquaculture Research

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Catfish hatcheries use copper sulfate (CuSO4) as an economical control for saprolegniasis on eggs. This study determines hatch rate of channel catfish eggs in hatching troughs containing 23.8°C flow-through well water when treated with 100 mg/L CuSO4 (ten times the proposed therapeutic dose). Eggs...

  11. Laser assisted zona hatching does not improve live birth rate in patients undergoing their first ICSI cycles

    PubMed Central

    Razi, Mohammad Hossein; Halvaei, Iman; Razi, Yasamin

    2013-01-01

    Background: Routine use of assisted hatching (AH) following ICSI is a controversial issue in the literature. There are rare studies regarding the effect of laser assisted hatching (LAH) on live birth rate. Objective: Our main goal was to evaluate the effect of LAH on delivery rate as well as congenital anomaly in patients undergoing their first ICSI cycle. Materials and Methods: A total of 182 patients subjected to ICSI were randomly aliquot into two groups of experiment and control. In experiment group, the embryos were subjected to LAH to open a hole in ZP (about 10-12 µm) while in control group, the transferred embryos were intact with no AH. The patients were followed for clinical pregnancy and delivery rate as well as congenital anomaly. All the patients were infertile due to male factor infertility and LAH and embryo transfer were done on day 2. Results: Laboratory and clinical characteristics of two groups of experiment and control were the same. There were insignificant differences between two groups of experiment and control for clinical pregnancy rate (20% vs. 23.9%, respectively, p=0.3) and live birth rate (11.11% vs. 8.6%, respectively, p=0.6). Also no significant differences were observed between two groups of experiment and control for multiple pregnancy as well as congenital anomaly. Conclusion: Routine use of LAH in first ICSI cycle for male factor patients may have no beneficial effects on clinical pregnancy and live birth rate. PMID:24639729

  12. From facultative to obligatory parental care: Interspecific variation in offspring dependency on post-hatching care in burying beetles.

    PubMed

    Capodeanu-Nägler, Alexandra; Keppner, Eva M; Vogel, Heiko; Ayasse, Manfred; Eggert, Anne-Katrin; Sakaluk, Scott K; Steiger, Sandra

    2016-01-01

    Studies on the evolution of parental care have focused primarily on the costs and benefits of parental care and the life-history attributes that favour it. However, once care evolves, offspring in some taxa appear to become increasingly dependent on their parents. Although offspring dependency is a central theme in family life, the evolutionary dynamics leading to it are not fully understood. Beetles of the genus Nicrophorus are well known for their elaborate biparental care, including provisioning of their young. By manipulating the occurrence of pre- or post-hatching care, we show that the offspring of three burying beetle species, N. orbicollis, N. pustulatus, and N. vespilloides, show striking variation in their reliance on parental care. Our results demonstrate that this variation within one genus arises through a differential dependency of larvae on parental feeding, but not on pre-hatching care. In N. pustulatus, larvae appear to be nutritionally independent of their parents, but in N. orbicollis, larvae do not survive in the absence of parental feeding. We consider evolutionary scenarios by which nutritional dependency may have evolved, highlighting the role of brood size regulation via infanticide in this genus. PMID:27378180

  13. From facultative to obligatory parental care: Interspecific variation in offspring dependency on post-hatching care in burying beetles

    PubMed Central

    Capodeanu-Nägler, Alexandra; Keppner, Eva M.; Vogel, Heiko; Ayasse, Manfred; Eggert, Anne-Katrin; Sakaluk, Scott K.; Steiger, Sandra

    2016-01-01

    Studies on the evolution of parental care have focused primarily on the costs and benefits of parental care and the life-history attributes that favour it. However, once care evolves, offspring in some taxa appear to become increasingly dependent on their parents. Although offspring dependency is a central theme in family life, the evolutionary dynamics leading to it are not fully understood. Beetles of the genus Nicrophorus are well known for their elaborate biparental care, including provisioning of their young. By manipulating the occurrence of pre- or post-hatching care, we show that the offspring of three burying beetle species, N. orbicollis, N. pustulatus, and N. vespilloides, show striking variation in their reliance on parental care. Our results demonstrate that this variation within one genus arises through a differential dependency of larvae on parental feeding, but not on pre-hatching care. In N. pustulatus, larvae appear to be nutritionally independent of their parents, but in N. orbicollis, larvae do not survive in the absence of parental feeding. We consider evolutionary scenarios by which nutritional dependency may have evolved, highlighting the role of brood size regulation via infanticide in this genus. PMID:27378180

  14. Comparative analysis of hatching rates and clutch sizes of Nile crocodile (Crocodylus niloticus) eggs collected on- and off-farm in Zimbabwe.

    PubMed

    Khosa, Patricia; Imbayarwo-Chikosi, Venancio Edward; Hamandishe, Vimbai

    2012-04-01

    The Nile crocodile (Crocodylus niloticus) is a large aquatic reptile predominant in the tropics in Africa and Zimbabwe in particular. Clutch sizes and hatching rates of Nile crocodile eggs collected from the wild and on-farm in Lowveld, Highveld and Kariba regions of Zimbabwe were evaluated. A total of 274 egg records for the period 2000 to 2008 from 39 farms were collected from the Crocodile Farmers Association of Zimbabwe. The effect of source of eggs was analysed using the non-parametric one way analysis of variance procedure of SAS Version 9.1.3. Wilcoxon signed rank test for independent samples was used to compare the mean hatching rates and clutch sizes for eggs collected from the different sources by region. The degree of association between clutch sizes and the hatching rates by source and region was determined using the Spearman's rank correlation test. Source of eggs had no effect (P > 0.05) on hatching rates in all the regions but significantly influenced (P < 0.05) clutch sizes in Lowveld and Kariba. In these regions, clutch sizes in the wild were significantly (P < 0.05) higher than those on-farm. Correlation estimates between clutch size and hatching rates were weak and non-significant (P > 0.05) for the different sources of eggs in all regions. Full utilization of the wild resource would reduce challenges relating to shortage of captive breeders and high cost of rearing breeders and hence increase productivity. PMID:21947863

  15. 76 FR 32188 - Hatch Solar Energy Center 1, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-03

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Hatch Solar Energy Center 1, LLC; Supplemental Notice That Initial... notice in the above-referenced proceeding of Hatch Solar Energy Center 1, LLC's application for...

  16. Comparison of three lines of broiler breeders differing in ascites susceptibility or growth rate. 1. Relationship between acoustic resonance data and embryonic or hatching parameters.

    PubMed

    Tona, K; Kemps, B; Bruggeman, V; Bamelis, F; De Smit, L; Onagbesan, O; De Baerdemaeker, J; Decuypere, E

    2005-09-01

    Ascites is a prevalent cardiovascular disease among modern broilers with negative impacts on production and animal welfare. The peak of mortality due to ascites occurs at the end of the growing period, but the etiology of this problem may start during embryonic development. A few recent reports have demonstrated that the signs of ascites susceptibility are manifested during the late stages of incubation. In the current study, we used a nondestructive method based on egg acoustic resonance parameters [resonant frequency (RF) and damping] to establish a relationship between embryo physiological events during early development in broiler eggs and susceptibility to ascites. The hatching eggs of 3 broiler lines differing in ascites susceptibility were used for this study: ascites-resistant dam line (DAR), ascites-sensitive dam line (DAS), and ascites-sensitive sire line (SASL). These lines were selected on the basis of fast growth, high breast meat yield, and ascites induction at low temperatures such that the order of ascites susceptibility in terms of mortality was SASL > DAS > DAR. Eggs were incubated under standard conditions in forced-draft incubators. We measured egg weights at setting, albumen pH, Haugh units (HU) at setting, and embryo weights at d 11 and 18, at internal pipping (IP), and at hatch. The durations of IP, external pipping (EP), and hatching were also determined. At 2 hourly periods during incubation, egg RF and damping were also measured. There were differences in egg weights between DAR and SASL vs. DAS, but albumen HU, albumen pH, and the ratio of yolk weight to egg weight were similar. There were differences in RF, damping, embryonic growth rates, and hatching events. Changes in resonant frequency and damping, which certainly suggest eggshell differences among lines, were not totally related to variations in physiological events during early and late embryonic development. A comparison between DAR and DAS, between DAS and SASL, or DAR and SASL

  17. Glassfrog embryos hatch early after parental desertion.

    PubMed

    Delia, Jesse R J; Ramírez-Bautista, Aurelio; Summers, Kyle

    2014-06-22

    Both parental care and hatching plasticity can improve embryo survival. Research has found that parents can alter hatching time owing to a direct effect of care on embryogenesis or via forms of care that cue the hatching process. Because parental care alters conditions critical for offspring development, hatching plasticity could allow embryos to exploit variation in parental behaviour. However, this interaction of parental care and hatching plasticity remains largely unexplored. We tested the hypothesis that embryos hatch early to cope with paternal abandonment in the glassfrog Hyalinobatrachium fleischmanni (Centrolenidae). We conducted male-removal experiments in a wild population, and examined embryos' response to conditions with and without fathers. Embryos hatched early when abandoned, but extended development in the egg stage when fathers continued care. Paternal care had no effect on developmental rate. Rather, hatching plasticity was due to embryos actively hatching at different developmental stages, probably in response to deteriorating conditions without fathers. Our experimental results are supported by a significant correlation between the natural timing of abandonment and hatching in an unmanipulated population. This study demonstrates that embryos can respond to conditions resulting from parental abandonment, and provides insights into how variation in care can affect selection on egg-stage adaptations. PMID:24789892

  18. Glassfrog embryos hatch early after parental desertion

    PubMed Central

    Delia, Jesse R. J.; Ramírez-Bautista, Aurelio; Summers, Kyle

    2014-01-01

    Both parental care and hatching plasticity can improve embryo survival. Research has found that parents can alter hatching time owing to a direct effect of care on embryogenesis or via forms of care that cue the hatching process. Because parental care alters conditions critical for offspring development, hatching plasticity could allow embryos to exploit variation in parental behaviour. However, this interaction of parental care and hatching plasticity remains largely unexplored. We tested the hypothesis that embryos hatch early to cope with paternal abandonment in the glassfrog Hyalinobatrachium fleischmanni (Centrolenidae). We conducted male-removal experiments in a wild population, and examined embryos' response to conditions with and without fathers. Embryos hatched early when abandoned, but extended development in the egg stage when fathers continued care. Paternal care had no effect on developmental rate. Rather, hatching plasticity was due to embryos actively hatching at different developmental stages, probably in response to deteriorating conditions without fathers. Our experimental results are supported by a significant correlation between the natural timing of abandonment and hatching in an unmanipulated population. This study demonstrates that embryos can respond to conditions resulting from parental abandonment, and provides insights into how variation in care can affect selection on egg-stage adaptations. PMID:24789892

  19. Post-hatching development of mitochondrial function, organ mass and metabolic rate in two ectotherms, the American alligator (Alligator mississippiensis) and the common snapping turtle (Chelydra serpentina).

    PubMed

    Sirsat, Sarah K G; Sirsat, Tushar S; Price, Edwin R; Dzialowski, Edward M

    2016-01-01

    The ontogeny of endothermy in birds is associated with disproportionate growth of thermogenic organs and increased mitochondrial oxidative capacity. However, no similar study has been made of the development of these traits in ectotherms. For comparison, we therefore investigated the metabolism, growth and muscle mitochondrial function in hatchlings of a turtle and a crocodilian, two ectotherms that never develop endothermy. Metabolic rate did not increase substantially in either species by 30 days post-hatching. Yolk-free body mass and heart mass did not change through 30 days in alligators and heart mass was a constant proportion of body mass, even after 1 year. Yolk-free body mass and liver mass grew 36% and 27%, respectively, in turtles during the first 30 days post-hatch. The mass-specific oxidative phosphorylation capacity of mitochondria, assessed using permeabilized muscle fibers, increased by a non-significant 47% in alligator thigh and a non-significant 50% in turtle thigh over 30 days, but did not increase in the heart. This developmental trajectory of mitochondrial function is slower and shallower than that previously observed in ducks, which demonstrate a 90% increase in mass-specific oxidative phosphorylation capacity in thigh muscles over just a few days, a 60% increase in mass-specific oxidative phosphorylation capacity of the heart over a few days, and disproportionate growth of the heart and other organs. Our data thus support the hypothesis that these developmental changes in ducks represent mechanistic drivers for attaining endothermy. PMID:26962048

  20. Post-hatching development of mitochondrial function, organ mass and metabolic rate in two ectotherms, the American alligator (Alligator mississippiensis) and the common snapping turtle (Chelydra serpentina)

    PubMed Central

    Sirsat, Sarah K. G.; Sirsat, Tushar S.; Price, Edwin R.; Dzialowski, Edward M.

    2016-01-01

    ABSTRACT The ontogeny of endothermy in birds is associated with disproportionate growth of thermogenic organs and increased mitochondrial oxidative capacity. However, no similar study has been made of the development of these traits in ectotherms. For comparison, we therefore investigated the metabolism, growth and muscle mitochondrial function in hatchlings of a turtle and a crocodilian, two ectotherms that never develop endothermy. Metabolic rate did not increase substantially in either species by 30 days post-hatching. Yolk-free body mass and heart mass did not change through 30 days in alligators and heart mass was a constant proportion of body mass, even after 1 year. Yolk-free body mass and liver mass grew 36% and 27%, respectively, in turtles during the first 30 days post-hatch. The mass-specific oxidative phosphorylation capacity of mitochondria, assessed using permeabilized muscle fibers, increased by a non-significant 47% in alligator thigh and a non-significant 50% in turtle thigh over 30 days, but did not increase in the heart. This developmental trajectory of mitochondrial function is slower and shallower than that previously observed in ducks, which demonstrate a 90% increase in mass-specific oxidative phosphorylation capacity in thigh muscles over just a few days, a 60% increase in mass-specific oxidative phosphorylation capacity of the heart over a few days, and disproportionate growth of the heart and other organs. Our data thus support the hypothesis that these developmental changes in ducks represent mechanistic drivers for attaining endothermy. PMID:26962048

  1. Perinatal broiler physiology between hatching and chick collection in 2 hatching systems.

    PubMed

    van de Ven, L J F; van Wagenberg, A V; Decuypere, E; Kemp, B; van den Brand, H

    2013-04-01

    Little is known about physiological responses of early- versus late-hatching chicks to early posthatch conditions in broiler practice. We investigated effects of hatching time on perinatal broiler physiology in 2 hatching systems, differing in conditions: a conventional hatcher, where chicks are deprived of feed and water between hatching and the moment of chick pulling (d E21.5), and a patio system, in which the hatching and brooding phase are combined, and chicks have immediate posthatch feed and water access. Climate conditions in patio also differ with about 3°C lower temperature and 20% lower RH compared with conventional hatchers. At E18, fertile eggs were transferred to either a hatcher or the patio until the end of incubation. From each system, 50 newly hatched chicks were collected at 3 hatching times: at 468 h (early), 483 h (midterm), and 498 h (late) of incubation, of which 25 chicks were decapitated for analyses of physiological parameters. The other 25 chicks were returned to the hatching system for analyses after 515 h of incubation (E21.5). At hatch, weights of the heart, lungs, stomach, and intestine increased with hatching time, concurrent with a decrease in residual yolk weight, regardless of hatching system, and indicating that later hatching chicks are more matured. Weights of the heart, liver, stomach, and intestines were lower in hatcher than in patio chicks. Between hatch and E21.5, residual yolk weight decreased, whereas organ weights increased in both fasted hatcher and fed patio chicks, but at a higher rate in the latter. At E21.5, plasma glucose and triiodothyronine had increased with time after hatch in patio chicks, whereas levels were similar among hatching times and lower in hatcher chicks. Early feed and water access seems to enable early hatching chicks to compensate for their apparent disadvantage in development at hatching, whereas chicks subjected to fasting show metabolic adaptations to preserve nutrients. Chick physiology at

  2. Expedition 30 Hatch Opening

    NASA Video Gallery

    Expedition 30 Flight Engineers Don Pettit, Oleg Kononenko and Andre Kuipers are welcomed aboard the International Space Station when the hatches between the station and the Soyuz TMA-03M spacecraft...

  3. Dose-rate dependence of heat radiosensitization

    SciTech Connect

    Gerner, E.W.; Oval, J.H.; Manning, M.R.; Sim, D.A.; Bowden, G.T.; Hevezi, J.M.

    1983-09-01

    The dose rate dependence of heat radiosensitization was studied using rat astrocytoma cells in culture and a cliniclly relevant protocol of heat dose and heat radiation sequence. Cells were treated with a minimally toxic heat dose of 43/sup 0/C for 30 minutes, after which they were irradiated with varying doses of radiation at dose rates ranging from 0.567 to 300 cGy/min. This heat dose substantially reduced the extrapolation number (n), but had little effect on D/sub 0/ of the radiation survival curve at dose rates of 50 cGy/min or greater. At dose rates less than 10 cGy/min, 43/sup 0/C for 30 min had little effect on n and only for the lowest dose rate studied (0.567 cGy/min) was there a significant reduction in D/sub 0/ (60%). The thermal enhancement ratio did not vary inversely with radiation dose rate over the dose rate range studied but, instead, was maximal at the two dose rate extremes (0.567 and 300 cGy/min). These data demonstrate that a clinically relevant heat dose enhances very low dose rate, as well as high dose rate, ionizing radiation, but suggest that little benefit is to be gained from using dose rates intermediate between conventional radiotherapeutic high dose rates or dose rates representative of interstitial implants.

  4. Hatching Behavior of Potato Cyst Nematodes from the Canary Islands

    PubMed Central

    Gonzalez, J. A.; Phillips, M. S.

    1996-01-01

    The present work investigated early hatching differences in naturally occuring field populations and newly reared populations of potato cyst nematodes from the Canary Islands. Hatching behavior of the two species appears to be distinct, with more juveniles hatched from G. pallida that hatch earlier and over a shorter time than G. rostochiensis. The hatching rate of 3-year-old PCN populations was more than double (mean 44.5% ñ 1) that shown by newly reared populations (mean 19.1% ñ 12.5), and those that could be classified as pathotype Pa 1 (Pa 1 and P 13) were found to hatch particularly poorly. Significant differences were also observed in the juveniles released in tap water between newly reared populations of both species, with mean hatch significantly higher for G. rostochiensis. The results are discussed in relation to the implication that these findings may have for competition between the two species of PCN in the field. PMID:19277163

  5. Hatching response of Aedes aegypti (Diptera: Culicidae) eggs at low temperatures: effects of hatching media and storage conditions.

    PubMed

    Byttebier, B; De Majo, M S; De Majo, M S; Fischer, S

    2014-01-01

    In temperate regions, Aedes aegypti (L.) (Diptera: Culicidae) populations remain in the egg stage during the cold season. To ensure the start of a new breeding season, eggs should hatch at the beginning of a favorable period. The aim of the current study was to investigate the hatching response of two Ae. aegypti egg batches collected and stored for 3 mo under different conditions, to different low immersion temperatures. Two different hatching media (water and yeast solution) were used for the first batch and only one (water) for the second egg batch. Eggs were immersed for 8 d, during which the number of hatched eggs was recorded daily. The proportion of hatched eggs, delay of the hatching response, proportion of dead larvae, and proportion of remaining eggs within the first egg batch were compared between the two hatching media at each temperature. These parameters also were compared between the two batches immersed in water. Hatching rates were higher and faster in the yeast solution. The hatching response was lower at lower immersion temperatures and among eggs stored under field conditions at colder temperatures (second batch). Among the eggs stored in the laboratory (first batch), older eggs exhibited lower hatching response. The proportion of dead larvae was higher in the yeast solution and in the eggs stored in the laboratory. The conditions that triggered a lower hatching response led to higher proportions of remaining eggs, allowing the population to maintain an egg bank for future favorable opportunities. PMID:24605458

  6. Nitric oxide regulates blastocyst hatching in mice

    PubMed Central

    Pan, Xiaoyan; Wang, Xuenan; Wang, Xiyan; Sun, Zhanxuan; Zhang, Xue; Liang, Xuanxuan; Li, Zhixin; Dou, Zhaohua

    2015-01-01

    Objective: This study is to determine the regulatory role of nitric oxide in mouse blastocyst hatching. Methods: Kunming female mice were superovulated and then mated with mature male mice. On day 2.5 of their pregnancy, the pregnant mice were killed and morulae were flushed from their uterine horns with culture media. Morulae were cultured in media with different concentrations of N-nitro-L arginine methyl ester (L-NAME), sodium nitroprusside (SNP), 8-Br-3’-5’-cyclic guanosine monophosphate (8-Br-cGMP) or the combination of L-NAME with SNP or 8-Br-cGMP for 48 h. The hatched blastocysts were examined on day 5 and the expressions of epithelial nitric oxide synthase (eNOS) and active cysteinyl aspartate specific proteinase 3 (caspase 3) were observed under confocal laser scanning microscope. Results: L-NAME significantly reduced the expression of eNOS in blastocyst cells. With the increase of the concentrations of L-NAME, SNP or 8-Br-cGMP, blastocyst hatching rate was significantly lowered. In addition, 5 mM L-NAME, 2 μM SNP and 2 μM 8-Br-cGMP completely inhibited blastocyst hatching. Low concentrations of SNP or 8-Br-cGMP in culture media containing 5 mM L-NAME significantly reversed the inhibition of blastocyst hatching and promoted hatching development. Moreover, 5 mM L-NAME and 2 μM 8-Br-cGMP had no significant influence on the expression of active caspase 3 in blastocyst cells. SNP (> 500 nM) significantly increased the expression of active caspase 3 in blastocyst cells. Conclusions: NO/cGMP pathway plays an important role in mouse blastocyst hatching. Excessive or depleted NO can interrupt blastocyst hatching. Excessive NO leads to apoptosis of blastocyst cells. PMID:26221236

  7. A. Bernard Hatch.

    ERIC Educational Resources Information Center

    Executive Educator, 1984

    1984-01-01

    Bernard Hatch, the aggressive superintendent of schools in Dayton, Ohio, was voted out by the board of education despite an excellent record of accomplishments. His fate bodes ill for urban school districts in general, where those with the integrity and grit to do what is necessary often become unpopular. (TE)

  8. Rate-dependent spallation properties of tantalum

    SciTech Connect

    Johnson, J.N.; Hixson, R.S.; Tonks, D.L.; Zurek, A.K.

    1995-09-01

    Spallation experiments are conducted on high-purity tantalum using VISAR instrumentation for impact stresses of 9.5 GPa and 6.0 GPa. The high-amplitude experiment exhibits very rapid initial spall separation, while the low-amplitude shot is only slightly above the threshold for void growth and thus exhibits distinct rate-dependent spallation behavior. These experiments are analyzed in terms of simple tensile fracture criteria, a standard rate-dependent void-growth model, and a rate-dependent void growth model in which the expected plastic volume strain makes no contribution to the relaxation of the mean stress. Recovery tests and VISAR measurements suggest an additional resistance to spallation that follows the rapid coalescence of voids; this effect is termed the secondary spall resistance and is due to the convoluted nature of the spall plane and the resulting interlocking fracture pattern that is developed and for which the stress remains unrelieved until the spall planes have separated several hundred microns.

  9. Time-Dependent Rate Phenomenon in Viruses

    PubMed Central

    Aiewsakun, Pakorn

    2016-01-01

    ABSTRACT Among the most fundamental questions in viral evolutionary biology are how fast viruses evolve and how evolutionary rates differ among viruses and fluctuate through time. Traditionally, viruses are loosely classed into two groups: slow-evolving DNA viruses and fast-evolving RNA viruses. As viral evolutionary rate estimates become more available, it appears that the rates are negatively correlated with the measurement timescales and that the boundary between the rates of DNA and RNA viruses might not be as clear as previously thought. In this study, we collected 396 viral evolutionary rate estimates across almost all viral genome types and replication strategies, and we examined their rate dynamics. We showed that the time-dependent rate phenomenon exists across multiple levels of viral taxonomy, from the Baltimore classification viral groups to genera. We also showed that, by taking the rate decay dynamics into account, a clear division between the rates of DNA and RNA viruses as well as reverse-transcribing viruses could be recovered. Surprisingly, despite large differences in their biology, our analyses suggested that the rate decay speed is independent of viral types and thus might be useful for better estimation of the evolutionary time scale of any virus. To illustrate this, we used our model to reestimate the evolutionary timescales of extant lentiviruses, which were previously suggested to be very young by standard phylogenetic analyses. Our analyses suggested that these viruses are millions of years old, in agreement with paleovirological evidence, and therefore, for the first time, reconciled molecular analyses of ancient and extant viruses. IMPORTANCE This work provides direct evidence that viral evolutionary rate estimates decay with their measurement timescales and that the rate decay speeds do not differ significantly among viruses despite the vast differences in their molecular features. After adjustment for the rate decay dynamics, the

  10. Hatching Eggs in the Classroom.

    ERIC Educational Resources Information Center

    Smith, Robert W.

    1984-01-01

    This article provides detailed instructions on how to hatch chicken eggs. Sections include: (1) making the incubator; (2) making the brooder; (3) guidelines for hatching eggs; (4) from incubator to brooder; and (5) recommended readings. (JMK)

  11. Corticosterone stimulates hatching of late-term tree lizard embryos.

    PubMed Central

    Weiss, Stacey L.; Johnston, Gwynne; Moore, Michael C.

    2007-01-01

    The regulation of hatching in oviparous animals is important for successful reproduction and survival, but is poorly understood. We unexpectedly found that RU-486, a progesterone and glucocorticoid antagonist, interferes with hatching of viable tree lizard (Urosaurus ornatus) embryos in a dose-dependent manner and hypothesized that embryonic glucocorticoids regulate hatching. To test this hypothesis, we treated eggs with corticosterone (CORT) or vehicle on Day 30 (85%) of incubation, left other eggs untreated, and observed relative hatch order and hatch time. In one study, the CORT egg hatched first in 9 of 11 clutches. In a second study, the CORT egg hatched first in 9 of 12 clutches, before vehicle-treated eggs in 10 of 12 clutches, and before untreated eggs in 7 of 9 clutches. On average, CORT eggs hatched 18.2h before vehicle-treated eggs and 11.6h before untreated eggs. Thus, CORT accelerates hatching of near-term embryos and RU-486 appears to block this effect. CORT may mobilize energy substrates that fuel hatching and/or accelerate lung development, and may provide a mechanism by which stressed embryos escape environmental stressors. PMID:17208477

  12. Mechanism Guides Hatch Through Hatchway

    NASA Technical Reports Server (NTRS)

    Barron, Daniel R.; Kennedy, Steven E.

    1993-01-01

    Elliptical hatch designed to move through hatchway to make pressure-assisted seal with either side of bulkhead. Compact three-degree-of-freedom mechanism guides hatch through hatchway or holds hatch off to one side to facilitate passage of crew and/or equipment. Hatches and mechanisms used in submarines, pressure chambers (including hyperbaric treatment chambers), vacuum chambers, and vacuum-or-pressure test chambers.

  13. Unusual distance dependences of electron transfer rates.

    PubMed

    Kuss-Petermann, Martin; Wenger, Oliver S

    2016-07-28

    Usually the rates for electron transfer (kET) decrease with increasing donor-acceptor distance, but Marcus theory predicts a regime in which kET is expected to increase when the transfer distance gets longer. Until recently, experimental evidence for such counter-intuitive behavior had been very limited, and consequently this effect is much less well-known than the Gaussian free energy dependence of electron transfer rates leading to the so-called inverted driving-force effect. This article presents the theoretical concepts that lead to the prediction of electron transfer rate maxima at large donor-acceptor distances, and it discusses conditions that are expected to favor experimental observations of such behavior. It continues with a consideration of specific recent examples in which electron transfer rates were observed to increase with increasing donor-acceptor distance, and it closes with a discussion of the importance of this effect in the context of light-to-chemical energy conversion. PMID:27353891

  14. 29 CFR 1918.31 - Hatch coverings.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 'tween-decks unless all hatch beams are in place under the hatch covers. (c) Missing, broken, or poorly... covers and hatch beams not of uniform size shall be placed only in the hatch, deck, and section in...

  15. 29 CFR 1918.31 - Hatch coverings.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 'tween-decks unless all hatch beams are in place under the hatch covers. (c) Missing, broken, or poorly... covers and hatch beams not of uniform size shall be placed only in the hatch, deck, and section in...

  16. 29 CFR 1918.31 - Hatch coverings.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 'tween-decks unless all hatch beams are in place under the hatch covers. (c) Missing, broken, or poorly... covers and hatch beams not of uniform size shall be placed only in the hatch, deck, and section in...

  17. Rate-dependent incompleteness of earthquake catalogs

    NASA Astrophysics Data System (ADS)

    Hainzl, Sebastian

    2016-04-01

    Important information about the earthquake generation process can be gained from instrumental earthquake catalogs, but this requires complete recordings to avoid biased results. The local completeness magnitude Mc is known to depend on general conditions such as the seismographic network and the environmental noise, which generally limit the possibility to detect small events. The detectability can be additionally reduced by an earthquake-induced increase of the noise-level leading to short-term variations of Mc, which cannot be resolved by traditional methods relying on the analysis of the frequency-magnitude distribution. Based on simple assumptions, I propose a new method to estimate such temporal excursions of Mc solely based on the estimation of the earthquake rate resulting in a high temporal resolution of Mc. The approach is shown to be in agreement with the apparent decrease of the estimated Gutenberg-Richter b-value in high-activity phases of recorded data sets and the observed incompleteness periods after mainshocks. Furthermore, an algorithm to estimate temporal changes of Mc is introduced and applied to empirical aftershock and swarm sequences from California and central Europe, indicating that observed b-value fluctuations are often related to rate-dependent incompleteness of the earthquake catalogs.

  18. Aspects of hatching success and chick survival in Gull-billed Terns in coastal Virginia

    USGS Publications Warehouse

    Eyler, T.B.; Erwin, R.M.; Stotts, D.B.; Hatfield, J.S.

    1999-01-01

    Because of a long-term population decline in Gull-billed Terns (Sterna nilotica) nesting along the coast of Virginia, we began a three year study in 1994 to monitor hatching success and survival of Gull-billed Tern chicks at several Virginia colony sites. Colonies were located on either small, storm-deposited shellpiles along marsh fringes or large, sandshell overwash fans of barrier islands. Nests were monitored one to three times a week for hatching success, and enclosures were installed around selected nests to monitor chick survival from hatching to about two weeks of age. Hatching success was lower in marsh colonies than island colonies, and was lower in 1995 than in 1994 and 1996, primarily because of flooding. The average brood size of nests where at least one chick hatched was 1.99 chicks. Survival rates of chicks to 14 days depended on hatch order and year but not brood size (one vs. two or more) or time of season. A-chicks had higher survival rates than B-chicks and third-hatched C-chicks (0.661 compared to 0.442 and 0.357, respectively). The year effect was significant only for A-chicks, with lower survival in 1994 (0.50) than in 1995 (0.765) or 1996 (0.758). Overall, productivity was low (0.53 chick per nest) compared to estimates for colonies in Denmark, and was attributable to nest flooding by spring and storm-driven high tides and chick predation, presumably mostly by Great Horned Owls (Bubo virginianus).

  19. Heart Rate Dependency of Large Artery Stiffness.

    PubMed

    Tan, Isabella; Spronck, Bart; Kiat, Hosen; Barin, Edward; Reesink, Koen D; Delhaas, Tammo; Avolio, Alberto P; Butlin, Mark

    2016-07-01

    Carotid-femoral pulse wave velocity (cfPWV) quantifies large artery stiffness, it is used in hemodynamic research and is considered a useful cardiovascular clinical marker. cfPWV is blood pressure (BP) dependent. Intrinsic heart rate (HR) dependency of cfPWV is unknown because increasing HR is commonly accompanied by increasing BP. This study aims to quantify cfPWV dependency on acute, sympathovagal-independent changes in HR, independent of BP. Individuals (n=52, age 40-93 years, 11 female) with in situ cardiac pacemakers or cardioverter defibrillators were paced at 60, 70, 80, 90, and 100 bpm. BP and cfPWV were measured at each HR. Both cfPWV (mean [95% CI], 0.31 [0.26-0.37] m/s per 10 bpm; P<0.001) and central aortic diastolic pressure (3.78 [3.40-4.17] mm Hg/10 bpm; P<0.001) increased with HR. The HR effect on cfPWV was isolated by correcting the BP effects by 3 different methods: (1) statistically, by a linear mixed model; (2) mathematically, using an exponential relationship between BP and cross-sectional lumen area; and (3) using measured BP dependency of cfPWV derived from changes in BP induced by orthostatic changes (seated and supine) in a subset of subjects (n=17). The BP-independent effects of HR on cfPWV were quantified as 0.20 [0.11-0.28] m/s per 10 bpm (P<0.001, method 1), 0.16 [0.11-0.22] m/s per 10 bpm (P<0.001, method 2), and 0.16 [0.11-0.21] m/s per 10 bpm (P<0.001, method 3). With a mean HR dependency in the range of 0.16 to 0.20 m/s per 10 bpm, cfPWV may be considered to have minimal physiologically relevant changes for small changes in HR, but larger differences in HR must be considered as contributing to significant differences in cfPWV. PMID:27245180

  20. Effects of partial or complete laser-assisted hatching on the hatching of mouse blastocysts and their cell numbers

    PubMed Central

    2013-01-01

    Background It is still debatable whether a full-thickness assisted hatching (AH) is better than the partial zona thinning. In this research, we used a mouse model to study the effect of partial and complete laser-AH on the rate of completely hatched blastocyst and their cell numbers. Methods In experiment 1, mouse morulae had 0, 1, 2 or 3 full-thickness openings of 10 microns created in the zona pellucida with an infrared laser beam. In the second experiment, 0, 1 and 2 openings of 20 microns were studied. In the third experiment, a full-thickness opening of 20 microns or quarter-thinning of the zonal circumference to a depth of 90% was compared with non-AH controls. Results No difference in blastocyst formation was found in laser-treated groups and in the controls. In experiment 1, the rate of completely hatched blastocysts was significantly lower than the controls. In experiment 2 when the size of the opening was increased, blastocysts completely hatched at a significantly higher rate than that in the controls. In experiment 3, the rate of completely hatched blastocysts was the highest in the full-thickness group. Cell numbers in completely hatched blastocysts from both AH groups were significantly fewer than those in the controls. Conclusions Full-thickness opening resulted in a higher rate of completely hatched blastocysts than quarter zonal-thinning and controls, but the cell numbers were significantly decreased. PMID:23510434

  1. Station Crew Opens Dragon Hatch

    NASA Video Gallery

    Expedition 33 Commander Suni Williams and Flight Engineer Aki Hoshide opened the hatch to the SpaceX Dragon cargo ship at 1:40 p.m. EDT Wednesday, Oct. 10, marking a milestone for the first commerc...

  2. Station Crew Opens Dragon's Hatch

    NASA Video Gallery

    The hatch between the newly arrived SpaceX Dragon spacecraft and the Harmony module of the International Space Station was opened by NASA Astronaut Don Pettit at 5:53 am EDT as the station flew 253...

  3. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Rate for additional dependent. 3.650 Section 3.650 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Adjustments and Resumptions § 3.650 Rate for additional dependent....

  4. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Rate for additional dependent. 3.650 Section 3.650 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation Adjustments and Resumptions § 3.650 Rate for additional dependent....

  5. Size-dependent mortality rate profiles.

    PubMed

    Roa-Ureta, Ruben H

    2016-08-01

    Knowledge of mortality rates is crucial to the understanding of population dynamics in populations of free-living fish and invertebrates in marine and freshwater environments, and consequently to sustainable resource management. There is a well developed theory of population dynamics based on age distributions that allow direct estimation of mortality rates. However, for most cases the aging of individuals is difficult or age distributions are not available for other reasons. The body size distribution is a widely available alternative although the theory underlying the formation of its shape is more complicated than in the case of age distributions. A solid theory of the time evolution of a population structured by any physiological variable has been developed in 1960s and 1970s by adapting the Hamilton-Jacobi formulation of classical mechanics, and equations to estimate the body size-distributed mortality profile have been derived for simple cases. Here I extend those results with regards to the size-distributed mortality profile to complex cases of non-stationary populations, individuals growing according to a generalised growth model and seasonally patterned recruitment pulses. I apply resulting methods to two cases in the marine environment, a benthic crustacean population that was growing during the period of observation and whose individuals grow with negative acceleration, and a sea urchin coastal population that is undergoing a stable cycle of two equilibrium points in population size whose individuals grow with varying acceleration that switches sign along the size range. The extension is very general and substantially widens the applicability of the theory. PMID:27164999

  6. NSA AERI Hatch Correction Data Set

    DOE Data Explorer

    Turner, David

    2012-03-23

    From 2000-2008, the NSA AERI hatch was determined to be indicated as open too frequently. Analysis suggests that the hatch was actually opening and closing properly but that its status was not being correctly reported by the hatch controller to the datastream. An algorithm was written to determine the hatch status from the observed

  7. A model study with light-dependent mortality rates of copepod stages

    NASA Astrophysics Data System (ADS)

    Neumann, Thomas; Kremp, Christine

    2005-06-01

    This paper is based on an advanced ecosystem model of the Baltic Sea (ERGOM [ J. Mar. Sys. 25 (3-4) (2005) 405]), but with an increased resolution of the zooplankton stage variable [ J. Plankton Res. 23 (2001) 1217; ICES Marine Science 219 (2003) 208]. The model copepods are represented by five stages: eggs, an aggregated variable of nauplii, two aggregated groups of copepodites and adults. The transfer among the stages, i.e., hatching, molting and reproduction, is controlled by food availability and temperature. As usual, the model food web is truncated at the level of zooplankton. The study explores the effects of different parametrization of zooplankton mortality and looks in particular on light-dependent rates. The light climate may serve a proxy for the effects of visual feeding of fish larvae and fish. Different choices of the mortality parameters can result in remarkable differences in abundances and biomass of the model zooplankton and in the timing of its development. It is found that the different choices of mortality affect the development of populations in several ways: Relative small initial differences of abundances at the beginning of the spring bloom are important for the development of the model populations. Higher mortality rates are less important at food rich conditions than at scarce resources. At low phytoplankton levels, the individual development of the copepods through the stages can be faster for elevated mortality rates because then less animals have to share the available food.

  8. Circadian rhythms of embryonic development and hatching in fish: a comparative study of zebrafish (diurnal), Senegalese sole (nocturnal), and Somalian cavefish (blind).

    PubMed

    Villamizar, Natalia; Blanco-Vives, Borja; Oliveira, Catarina; Dinis, Maria Teresa; Di Rosa, Viviana; Negrini, Pietro; Bertolucci, Cristiano; Sánchez-Vázquez, Francisco Javier

    2013-08-01

    During early development, most organisms display rhythmic physiological processes that are shaped by daily changes in their surrounding environment (i.e., light and temperature cycles). In fish, the effects of daily photocycles and their interaction with temperature during early developmental stages remain largely unexplored. We investigated the existence of circadian rhythms in embryonic development and hatching of three teleost species with different daily patterns of behavior: diurnal (zebrafish), nocturnal (Senegalese sole), and blind, not entrained by light (Somalian cavefish). To this end, fertilized eggs were exposed to three light regimes: 12 h of light: 12 h of darkness cycle (LD), continuous light (LL), or continuous darkness (DD); and three species-appropriate temperature treatments: 24°C, 28°C, or 32°C for zebrafish and cavefish and 18°C, 21°C, or 24°C for sole. The results pointed to the existence of daily rhythms of embryonic development and hatching synchronized to the LD cycle, with different acrophases, depending on the species: zebrafish embryos advanced their developmental stage during the light phase, whereas sole did so during the dark phase. In cavefish, embryogenesis occurred within 24 h post fertilization (hpf) at the same pace during day or night. The hatching rhythms appeared to be controlled by a clock mechanism that restricted or "gated" hatching to a particular time of day/night (window), so that embryos that reached a certain developmental state by that time hatch, whereas those that have not wait until the next available window. Under LL and DD conditions, hatching rhythms and the gating phenomenon persisted in cavefish, in zebrafish they split into ultradian bouts of hatching occurring at 12-18-h intervals, whereas in sole DD and LL produced a 24-h delay and advance, respectively. Hatching rates were best under the LD cycle and the reported optimal temperature for each species (95.2±2.7% of the zebrafish and 83.3±0.1% of the

  9. Item Response Models for Local Dependence among Multiple Ratings

    ERIC Educational Resources Information Center

    Wang, Wen-Chung; Su, Chi-Ming; Qiu, Xue-Lan

    2014-01-01

    Ratings given to the same item response may have a stronger correlation than those given to different item responses, especially when raters interact with one another before giving ratings. The rater bundle model was developed to account for such local dependence by forming multiple ratings given to an item response as a bundle and assigning…

  10. Hatching the Cleidoic Egg: The Role of Thyroid Hormones

    PubMed Central

    De Groef, Bert; Grommen, Sylvia V.H.; Darras, Veerle M.

    2013-01-01

    A major life stage transition in birds and other oviparous sauropsids is the hatching of the cleidoic egg. Not unlike amphibian metamorphosis, hatching in these species can be regarded as a transition from a relatively well-protected “aqueous” environment to a more hazardous and terrestrial life outside the egg, a transition in which thyroid hormones (THs) (often in concert with glucocorticoids) play an important role. In precocial birds such as the chicken, the perihatch period is characterized by peak values of THs. THs are implicated in the control of muscle development, lung maturation and the switch from chorioallantoic to pulmonary respiration, yolk sac retraction, gut development and induction of hepatic genes to accommodate the change in dietary energy source, initiation of thermoregulation, and the final stages of brain maturation as well as early post-hatch imprinting behavior. There is evidence that, at least for some of these processes, THs may have similar roles in non-avian sauropsids. In altricial birds such as passerines on the other hand, THs do not rise significantly until well after hatching and peak values coincide with the development of endothermy. It is not known how hatching-associated processes are regulated by hormones in these animals or how this developmental mode evolved from TH-dependent precocial hatching. PMID:23755041

  11. Comparison of different grading schemes in InGaAs metamorphic buffers on GaAs substrate: Tilt dependence on cross-hatch irregularities

    NASA Astrophysics Data System (ADS)

    Kumar, Rahul; Bag, Ankush; Mukhopadhyay, Partha; Das, Subhashis; Biswas, Dhrubes

    2015-12-01

    InGaAs graded metamorphic buffers (MBs) with different grading strategies have been grown by molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. A detailed comparative analysis of surface using atomic force microscopy (AFM), and bulk properties using high resolution X-ray diffraction (HRXRD) and room temperature photoluminescence (RTPL) of grown MBs have been presented to comprehend the effectiveness of different grading scheme on InGaAs MBs. Conventional, statistical and fractal analysis on measured AFM data has been performed for in-depth investigation of these surfaces. The grading scheme has been found to have little impact on residual strain while it affects the epitaxial tilt significantly. Moreover, the tilt has been found to depend on growth front irregularities. Tilt magnitude in a graded MB has been found to vary with composition while tilt azimuth has been found to be almost same in the graded layers. PL Intensity and a shift in the PL peaks have been used to study the quality of the MB and residual strain comparatively.

  12. Logarithmic rate dependence of force networks in sheared granular materials

    NASA Astrophysics Data System (ADS)

    Hartley, R. R.; Behringer, R. P.

    2003-02-01

    Many models of slow, dense granular flows assume that the internal stresses are independent of the shearing rate. In contrast, logarithmic rate dependence is found in solid-on-solid friction, geological settings and elsewhere. Here we investigate the rate dependence of stress in a slowly sheared two-dimensional system of photoelastic disks, in which we are able to determine forces on the granular scale. We find that the mean (time-averaged) stress displays a logarithmic dependence on the shear rate for plastic (irreversible) deformations. However, there is no perceivable dependence on the driving rate for elastic (reversible) deformations, such as those that occur under moderate repetitive compression. Increasing the shearing rate leads to an increase in the strength of the force network and stress fluctuations. Qualitatively, this behaviour resembles the changes associated with an increase in density. Increases in the shearing rate also lead to qualitative changes in the distributions of stress build-up and relaxation events. If shearing is suddenly stopped, stress relaxations occur with a logarithmic functional form over long timescales. This slow collective relaxation of the stress network provides a mechanism for rate-dependent strengthening.

  13. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... be effective from the date of potential entitlement of the additional dependent. (2) Where benefits... for periods prior to the date the full rate is awarded shall be the difference between the...

  14. 38 CFR 3.650 - Rate for additional dependent.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... be effective from the date of potential entitlement of the additional dependent. (2) Where benefits... for periods prior to the date the full rate is awarded shall be the difference between the...

  15. Rate dependent constitutive models for fiber reinforced polymer composites

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.

    1990-01-01

    A literature survey was conducted to assess the state-of-the-art in rate dependent constitutive models for continuous fiber reinforced polymer matrix composite (PMC) materials. Several recent models which include formulations for describing plasticity, viscoelasticity, viscoplasticity, and rate-dependent phenomenon such as creep and stress relaxation are outlined and compared. When appropriate, these comparisons include brief descriptions of the mathematical formulations, the test procedures required for generating material constants, and details of available data comparing test results to analytical predictions.

  16. Egg storage duration and hatch window affect gene expression of nutrient transporters and intestine morphological parameters of early hatched broiler chicks.

    PubMed

    Yalcin, S; Gursel, I; Bilgen, G; Izzetoglu, G T; Horuluoglu, B H; Gucluer, G

    2016-05-01

    In recent years, researchers have given emphasis on the differences in physiological parameters between early and late hatched chicks within a hatch window. Considering the importance of intestine development in newly hatched chicks, however, changes in gene expression of nutrient transporters in the jejunum of early hatched chicks within a hatch window have not been studied yet. This study was conducted to determine the effects of egg storage duration before incubation and hatch window on intestinal development and expression of PepT1 (H+-dependent peptide transporter) and SGLT1 (sodium-glucose co-transporter) genes in the jejunum of early hatched broiler chicks within a 30 h of hatch window. A total of 1218 eggs obtained from 38-week-old Ross 308 broiler breeder flocks were stored for 3 (ES3) or 14 days (ES14) and incubated at the same conditions. Eggs were checked between 475 and 480 h of incubation and 40 chicks from each egg storage duration were weighed; chick length and rectal temperature were measured. The chicks were sampled to evaluate morphological parameters and PepT1 and SGLT1 expression. The remaining chicks that hatched between 475 and 480 h were placed back in the incubator and the same measurements were conducted with those chicks at the end of hatch window at 510 h of incubation. Chick length, chick dry matter content, rectal temperature and weight of small intestine segments increased, whereas chick weight decreased during the hatch window. The increase in the jejunum length and villus width and area during the hatch window were higher for ES3 than ES14 chicks. PepT1 expression was higher for ES3 chicks compared with ES14. There was a 10.2 and 17.6-fold increase in PepT1 and SGLT1 expression of ES3 chicks at the end of hatch window, whereas it was only 2.3 and 3.3-fold, respectively, for ES14 chicks. These results suggested that egg storage duration affected development of early hatched chicks during 30 h of hatch window. It can be concluded that

  17. Hatch latch mechanism for Spacelab scientific airlock

    NASA Technical Reports Server (NTRS)

    Terhaar, G. R.

    1979-01-01

    The requirements, design tradeoff, design, and performance of the Spacelab scientific airlock hatch latching mechanisms are described. At space side the hatch is closed and held against internal airlock/module pressure by 12 tangential overcenter hooks driven by a driver. At module side the hatch is held by 4 hooks driven by rollers running on a cammed driver.

  18. 7 CFR 60.111 - Hatched.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hatched. 60.111 Section 60.111 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections... AND SHELLFISH General Provisions Definitions § 60.111 Hatched. Hatched means emerged from the egg....

  19. Long-range dependence in interest rates and monetary policy

    NASA Astrophysics Data System (ADS)

    Cajueiro, Daniel O.; Tabak, Benjamin M.

    2008-01-01

    This Letter studies the dynamics of Brazilian interest rates for short-term maturities. The Letter employs developed techniques in the econophysics literature and tests for long-range dependence in the term structure of these interest rates for the last decade. Empirical results suggest that the degree of long-range dependence has changed over time due to changes in monetary policy, specially in the short-end of the term structure of interest rates. Therefore, we show that it is possible to identify monetary arrangements using these techniques from econophysics.

  20. 78 FR 6173 - Diana Del Grosso, Ray Smith, Joseph Hatch, Cheryl Hatch, Kathleen Kelley, Andrew Wilklund, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-29

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF TRANSPORTATION Surface Transportation Board Diana Del Grosso, Ray Smith, Joseph Hatch, Cheryl Hatch, Kathleen... Smith, Joseph Hatch, Cheryl Hatch, Kathleen Kelley, Andrew Wilklund, and Richard Kosiba...

  1. Rate Dependent Deformation and Strength Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1999-01-01

    A research program is being undertaken to develop rate dependent deformation and failure models for the analysis of polymer matrix composite materials. In previous work in this program, strain-rate dependent inelastic constitutive equations used to analyze polymers have been implemented into a mechanics of materials based composite micromechanics method. In the current work, modifications to the micromechanics model have been implemented to improve the calculation of the effective inelastic strain. Additionally, modifications to the polymer constitutive model are discussed in which pressure dependence is incorporated into the equations in order to improve the calculation of constituent and composite shear stresses. The Hashin failure criterion is implemented into the analysis method to allow for the calculation of ply level failure stresses. The deformation response and failure stresses for two representative uniaxial polymer matrix composites, IM7/977-2 and AS4-PEEK, are predicted for varying strain rates and fiber orientations. The predicted results compare favorably to experimentally obtained values.

  2. Nonlinear Density Dependence of Singlet Fission Rate in Tetracene Films.

    PubMed

    Zhang, Bo; Zhang, Chunfeng; Wang, Rui; Tan, Zhanao; Liu, Yunlong; Guo, Wei; Zhai, Xiaoling; Cao, Yi; Wang, Xiaoyong; Xiao, Min

    2014-10-16

    Singlet fission holds the potential to dramatically improve the efficiency of solar energy conversion by creating two triplet excitons from one photoexcited singlet exciton in organic semiconductors. It is generally assumed that the singlet-fission rate is linearly dependent on the exciton density. Here we experimentally show that the rate of singlet fission has a nonlinear dependence on the density of photoexcited singlet excitons in tetracene films with small crystalline grains. We disentangle the spectrotemporal features of singlet and triplet dynamics from ultrafast spectroscopic data with the algorithm of singular value decomposition. The correlation between their temporal dynamics indicates a superlinear dependence of fission rate on the density of singlet excitons, which may arise from excitonic interactions. PMID:26278594

  3. Extreme-value dependence: An application to exchange rate markets

    NASA Astrophysics Data System (ADS)

    Fernandez, Viviana

    2007-04-01

    Extreme value theory (EVT) focuses on modeling the tail behavior of a loss distribution using only extreme values rather than the whole data set. For a sample of 10 countries with dirty/free float regimes, we investigate whether paired currencies exhibit a pattern of asymptotic dependence. That is, whether an extremely large appreciation or depreciation in the nominal exchange rate of one country might transmit to another. In general, after controlling for volatility clustering and inertia in returns, we do not find evidence of extreme-value dependence between paired exchange rates. However, for asymptotic-independent paired returns, we find that tail dependency of exchange rates is stronger under large appreciations than under large depreciations.

  4. Temperature Dependence of Radiative and Nonradiative Rates from Time-Dependent Correlation Function Methods.

    PubMed

    Banerjee, Shiladitya; Baiardi, Alberto; Bloino, Julien; Barone, Vincenzo

    2016-02-01

    The temperature dependence of the rate constants in radiative and nonradiative decays from excited electronic states has been studied using a time-dependent correlation function approach in the framework of the adiabatic representation and the harmonic oscillator approximation. The present work analyzes the vibrational aspect of the processes, which gives rise to the temperature dependence, with the inclusion of mode-mixing, as well as of frequency change effects. The temperature dependence of the rate constants shows a contrasting nature, depending on whether the process has been addressed within the Franck-Condon approximation or beyond it. The calculation of the Duschinsky matrix and the shift vector between the normal modes of the two states can be done in Cartesian and/or internal coordinates, depending on the flexibility of the investigated molecule. A new computational code has been developed to calculate the rates of intersystem crossing, internal conversion, and fluorescence for selected molecules as functions of temperature. PMID:26683207

  5. Assessing the prevalence of Salmonella enterica in poultry hatcheries by using hatched eggshell membranes.

    PubMed

    Chao, M-R; Hsien, C-H; Yeh, C-M; Chou, S-J; Chu, C; Su, Y-C; Yu, C-Y

    2007-08-01

    Salmonella enterica causes a number of significant poultry diseases and is also a major pathogen in humans. Most poultry infected by Salmonella become carriers; infection may also be fatal, depending on the particular serovar and the age of the bird at infection. Younger birds are more susceptible to infection by Salmonella, so it is critical that hatcheries monitor birds. We developed a method to use hatched eggshell membranes (HEM) to assess contamination by Salmonella in poultry hatching cabinets and to evaluate the prevalence of Salmonella in a goose hatchery and rearing farm. Comparison of the Salmonella isolation rate in hatching cabinets using 3 sampling methods showed that the highest Salmonella contamination was detected in HEM, and that these results differed significantly from those obtained from fluff samples and cabinet swab samples (P < 0.05). Analysis of HEM was also used to evaluate Salmonella contamination in goose, chicken, and duck hatcheries. The lowest Salmonella-positive rate was found for the chicken hatchery, followed by the goose and the duck hatcheries (P < 0.05). Six serogroups of Salmonella were detected in the 3 hatcheries: A, B, C1, C2, D, and E. The distribution of these serogroups differed among the hatcheries. Salmonella serogroup C1 was the major serogroup found in geese, compared with serogroup B in chickens and ducks. However, Salmonella Typhimurium was dominant in 1 goose hatchery and also in geese from this hatchery that had been transferred to a farm. Antibiotic susceptibility analysis showed that Salmonella Typhimurium strains isolated from the farm geese with diarrhea showed significantly higher resistance to doxycycline, colistin, sulfamethoxazole-trimethoprin, and cephalothin than those isolated from the hatchery (P < 0.05). Therefore, HEM as a detection target can be used to monitor Salmonella contamination in hatching cabinets and also be used to assess Salmonella prevalence in poultry hatcheries and rearing farms. PMID

  6. Strain rate dependency of laser sintered polyamide 12

    NASA Astrophysics Data System (ADS)

    Cook, J. E. T.; Goodridge, R. D.; Siviour, C. R.

    2015-09-01

    Parts processed by Additive Manufacturing can now be found across a wide range of applications, such as those in the aerospace and automotive industry in which the mechanical response must be optimised. Many of these applications are subjected to high rate or impact loading, yet it is believed that there is no prior research on the strain rate dependence in these materials. This research investigates the effect of strain rate and laser energy density on laser sintered polyamide 12. In the study presented here, parts produced using four different laser sintered energy densities were exposed to uniaxial compression tests at strain rates ranging from 10-3 to 10+3 s-1 at room temperature, and the dependence on these parameters is presented.

  7. Strain Rate Dependent Modeling of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1999-01-01

    A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. Strain rate dependent inelastic constitutive equations have been developed to model the polymer matrix, and have been incorporated into a micromechanics approach to analyze polymer matrix composites. The Hashin failure criterion has been implemented within the micromechanics results to predict ply failure strengths. The deformation model has been implemented within LS-DYNA, a commercially available transient dynamic finite element code. The deformation response and ply failure stresses for the representative polymer matrix composite AS4/PEEK have been predicted for a variety of fiber orientations and strain rates. The predicted results compare favorably to experimentally obtained values.

  8. Growth-rate-dependent dynamics of a bacterial genetic oscillator

    NASA Astrophysics Data System (ADS)

    Osella, Matteo; Lagomarsino, Marco Cosentino

    2013-01-01

    Gene networks exhibiting oscillatory dynamics are widespread in biology. The minimal regulatory designs giving rise to oscillations have been implemented synthetically and studied by mathematical modeling. However, most of the available analyses generally neglect the coupling of regulatory circuits with the cellular “chassis” in which the circuits are embedded. For example, the intracellular macromolecular composition of fast-growing bacteria changes with growth rate. As a consequence, important parameters of gene expression, such as ribosome concentration or cell volume, are growth-rate dependent, ultimately coupling the dynamics of genetic circuits with cell physiology. This work addresses the effects of growth rate on the dynamics of a paradigmatic example of genetic oscillator, the repressilator. Making use of empirical growth-rate dependencies of parameters in bacteria, we show that the repressilator dynamics can switch between oscillations and convergence to a fixed point depending on the cellular state of growth, and thus on the nutrients it is fed. The physical support of the circuit (type of plasmid or gene positions on the chromosome) also plays an important role in determining the oscillation stability and the growth-rate dependence of period and amplitude. This analysis has potential application in the field of synthetic biology, and suggests that the coupling between endogenous genetic oscillators and cell physiology can have substantial consequences for their functionality.

  9. Thermoluminescence in gallium sulfide crystals: an unusual heating rate dependence

    NASA Astrophysics Data System (ADS)

    Delice, S.; Bulur, E.; Gasanly, N. M.

    2015-03-01

    Trap centres in gallium sulfide single crystals have been investigated by thermoluminescence measurements in the temperature range of 10-230 K. A curve-fitting method was utilized to evaluate the activation energies (52, 200 and 304 meV) of the revealed three trap centres. The heating rate dependence and trap distribution of the peaks have been studied using experimental techniques based on various heating rates and various illumination temperatures, respectively. An anomalous heating rate dependence of the high-temperature peak was found by carrying out TL measurements with various heating rates between 0.2 and 1.0 K/s. This behaviour was explained on the basis of a semi-localized transition model. Whereas normal heating rate dependence was established for low-temperature peak, that is, the TL intensity of the glow curve decreases and the peak maximum temperature shifts to higher values with increasing the heating rate. Moreover, a quasi-continuous trap distribution with the increase of activation energies from 52 to 90 meV, from 200 to 268 meV and from 304 to 469 meV for the observed three different traps was established employing the various illumination temperatures method.

  10. Rate and time dependent failure of structural adhesives

    NASA Technical Reports Server (NTRS)

    Brinson, H. F.; Renieri, M. P.; Herakovich, C. T.

    1975-01-01

    Studies on two adhesives (Metlbond 1113 and 1113-2) identified as having important applications in the bonding of composite materials are presented. A testing program to ascertain stress-strain, strain-rate, time, yield, and/or failure behavior of these materials in bulk form using uniaxial tensile constant strain-rate, creep, and relaxation tests is described. The stress-strain behavior of each material is shown to be significantly rate dependent. A rate dependent stress whitening (crazing) phenomenon occurs prior to either yield or fracture. A region of linear elasticity, a region of viscoelasticity, and the onset of yielding are identified in the stress-strain behavior. The linear elastic limit and the yield point are shown to be rate dependent and agree well with an empirical equation proposed by Ludwik. A creep to failure phenomenon is shown to exist and is correlated with a delayed yield equation proposed by Crochet. Analytical predictions based on a modified Bingham model are shown to agree well with experimental stress-strain strain-rate data. Analytical predictions based on a modified Ramberg-Osgood equation are also shown for comparison purposes.

  11. Rate- and strain-dependent brittle deformation of rocks

    NASA Astrophysics Data System (ADS)

    Brantut, N.; Heap, M. J.; Baud, P.; Meredith, P. G.

    2014-03-01

    We develop a unifying framework to quantify rate-dependent deformation in the brittle field and establish links between the microscale time-dependent crack growth processes and the macroscopically observed rate dependency. Triaxial deformation experiments have been performed under both constant strain rate and constant stress (creep) conditions on three types of sandstone. The measured relative evolution of P wave speeds as a function of inelastic axial strain is similar for both types of test, despite differences in strain rate of up to 3 orders of magnitude. This similarity indicates that there exists a direct, time-independent link between the microstructural state (as reflected by the variations in P wave speed) and the inelastic axial strain. Comparison of applied stresses between constant strain rate and creep experiments as a function of inelastic strain indicates that creep deformation requires less mechanical work to bring the sample to failure. This energy deficit corresponds to a stress deficit, which can be related to a deficit in energy release rate of the microcracks. We establish empirically that the creep strain rate is given by ɛ˙∝exp(ΔQ/σ∗), where ΔQ is the stress deficit (negative) and σ∗ is an activation stress. This empirical exponential relation between creep strain rate and stress deficit is analogous to rate-and-state friction law. We develop a micromechanical approach based on fracture mechanics to determine the evolution of an effective stress intensity factor at crack tips during creep deformation and estimate the activation volume of the stress corrosion reaction responsible for brittle creep.

  12. Temperature dependence of nucleation rate in a binary solid solution

    NASA Astrophysics Data System (ADS)

    Wang, H. Y.; Philippe, T.; Duguay, S.; Blavette, D.

    2012-12-01

    The influence of regression (partial dissolution) effects on the temperature dependence of nucleation rate in a binary solid solution has been studied theoretically. The results of the analysis are compared with the predictions of the simplest Volmer-Weber theory. Regression effects are shown to have a strong influence on the shape of the curve of nucleation rate versus temperature. The temperature TM at which the maximum rate of nucleation occurs is found to be lowered, particularly for low interfacial energy (coherent precipitation) and high-mobility species (e.g. interstitial atoms).

  13. Heartbeat, embryo communication and hatching synchrony in snake eggs

    PubMed Central

    Aubret, Fabien; Blanvillain, Gaëlle; Bignon, Florent; Kok, Philippe J. R.

    2016-01-01

    Communication is central to life at all levels of complexity, from cells to organs, through to organisms and communities. Turtle eggs were recently shown to communicate with each other in order to synchronise their development and generate beneficial hatching synchrony. Yet the mechanism underlying embryo to embryo communication remains unknown. Here we show that within a clutch, developing snake embryos use heart beats emanating from neighbouring eggs as a clue for their metabolic level, in order to synchronise development and ultimately hatching. Eggs of the water snake Natrix maura increased heart rates and hatched earlier than control eggs in response to being incubated in physical contact with more advanced eggs. The former produced shorter and slower swimming young than their control siblings. Our results suggest potential fitness consequences of embryo to embryo communication and describe a novel driver for the evolution of egg-clustering behaviour in animals. PMID:26988725

  14. Heartbeat, embryo communication and hatching synchrony in snake eggs.

    PubMed

    Aubret, Fabien; Blanvillain, Gaëlle; Bignon, Florent; Kok, Philippe J R

    2016-01-01

    Communication is central to life at all levels of complexity, from cells to organs, through to organisms and communities. Turtle eggs were recently shown to communicate with each other in order to synchronise their development and generate beneficial hatching synchrony. Yet the mechanism underlying embryo to embryo communication remains unknown. Here we show that within a clutch, developing snake embryos use heart beats emanating from neighbouring eggs as a clue for their metabolic level, in order to synchronise development and ultimately hatching. Eggs of the water snake Natrix maura increased heart rates and hatched earlier than control eggs in response to being incubated in physical contact with more advanced eggs. The former produced shorter and slower swimming young than their control siblings. Our results suggest potential fitness consequences of embryo to embryo communication and describe a novel driver for the evolution of egg-clustering behaviour in animals. PMID:26988725

  15. Rate-dependent deformation of rocks in the brittle regime

    NASA Astrophysics Data System (ADS)

    Baud, P.; Brantut, N.; Heap, M. J.; Meredith, P. G.

    2013-12-01

    Rate-dependent brittle deformation of rocks, a phenomenon relevant for long-term interseismic phases of deformation, is poorly understood quantitatively. Rate-dependence can arise from chemically-activated, subcritical crack growth, which is known to occur in the presence of aqueous fluids. Here we attempt to establish quantitative links between this small scale process and its macroscopic manifestations. We performed a series of brittle deformation experiments in porous sandstones, in creep (constant stress) and constant strain rate conditions, in order to investigate the relationship between their short- and long-term mechanical behaviors. Elastic wave velocities measurements indicate that the amount of microcracking follows the amount of inelastic strain in a trend which does not depend upon the timescale involved. The comparison of stress-strain curves between constant strain rate and creep tests allows us to define a stress difference between the two, which can be viewed as a difference in energy release rate. We empirically show that the creep strain rates are proportional to an exponential function of this stress difference. We then establish a general method to estimate empirical micromechanical functions relating the applied stresses to mode I stress intensity factors at microcrack tips, and we determine the relationship between creep strain rates and stress intensity factors in our sandstone creep experiments. We finally provide an estimate of the sub-critical crack growth law parameters, and find that they match -within the experimental errors and approximations of the method- the typical values observed in independent single crack tests. Our approach provides a comprehensive and unifying explanation for the origin and the macroscopic manifestation of time-dependent brittle deformation in brittle rocks.

  16. Viscosity dependence of the rates of diffusional processes

    NASA Technical Reports Server (NTRS)

    Weaver, D. L.

    1982-01-01

    It is shown that the rates of diffusion-controlled processes may have a solvent vicosity independent part as well as a viscosity dependent part. Some relevant experiments involving intramolecular polypeptide movements are discussed, and implications for some experiments on diffusion in membranes are outlined.

  17. Condition-dependent mutation rates and sexual selection.

    PubMed

    Cotton, S

    2009-04-01

    'Good genes' models of sexual selection show that females can gain indirect benefits for their offspring if male ornaments are condition-dependent signals of genetic quality. Recurrent deleterious mutation is viewed as a major contributor to variance in genetic quality, and previous theoretical treatments of 'good genes' processes have assumed that the influx of new mutations is constant. I propose that this assumption is too simplistic, and that mutation rates vary in ways that are important for sexual selection. Recent data have shown that individuals in poor condition can have higher mutation rates, and I argue that if both male sexual ornaments and mutation rates are condition-dependent, then females can use male ornamentation to evaluate their mate's mutation rate. As most mutations are deleterious, females benefit from choosing well-ornamented mates, as they are less likely to contribute germline-derived mutations to offspring. I discuss some of the evolutionary ramifications of condition-dependent mutation rates and sexual selection. PMID:19210586

  18. The role of landscape features and density dependence in growth andfledging rates of Piping Plovers in North Dakota, USA

    USGS Publications Warehouse

    Anteau, Michael J.; Wiltermuth, Mark T.; Sherfy, Mark H.; Shaffer, Terry L.; Pearse, Aaron T.

    2014-01-01

    For species with precocial young, survival from hatching to fledging is a key factor influencing recruitment. Furthermore, growth rates of precocial chicks are an indicator of forage quality and habitat suitability of brood-rearing areas. We examined how growth and fledging rates of Piping Plover (Charadrius melodus) chicks were influenced by landscape features, such as hatchling density (hatchlings per hectare of remotely sensed habitat [H ha-1]), island vs. mainland, and wind fetch (exposure to waves) at 2-km segments (n ¼ 15) of Lake Sakakawea, North Dakota, during 2007–2008. Hatchling growth was comparable with published estimates for other habitats. Models for fledging rate (fledged young per segment) assuming density dependence had more support (wi ¼ 96%) than those assuming density independence (wi ¼ 4%). Density-dependent processes appeared to influence fledging rate only at densities .5 H ha-1, which occurred in 19% of the segments we sampled. When areas with densities .5 H ha-1 were excluded, density-dependence and density-independence models were equally supported (wi ¼ 52% and 48%, respectively). Fledging rate declined as the wind fetch of a segment increased. Fledging rate on mainland shorelines was 4.3 times greater than that on islands. Previous work has indicated that plovers prefer islands for nesting, but our results suggest that this preference is not optimal and could lead to an ecological trap for chicks. While other researchers have found nesting-habitat requirements to be gravelly areas on exposed beaches without fine-grain substrates, our results suggest that chicks fledge at lower rates in these habitats. Thus, breeding plovers likely require complexes of these nesting habitats along with protected areas with fine, nutrient-rich substrate for foraging by hatchlings.

  19. Rate-dependent undrained shear behavior of saturated clay

    SciTech Connect

    Sheahan, T.C.; Ladd, C.C.; Germaine, J.T.

    1996-02-01

    The paper describes results from 250 K{sub 0} consolidated-undrained triaxial compression tests on resedimented Boston blue clay using a computer-automated triaxial apparatus with lubricated end platens and a midheight pore-pressure measurement device. Specimens were consolidated to four over consolidation ratios (OCR = 1, 2, 4, or 8), and for each OCR, undrained shear was performed using four axial strain rates (0.05%, 0.5%, 5%, and 50%/h). The results show that the undrained strength (s{sub u}) rate sensitivity (percent increase in s{sub u} per log cycle strain rate) across the two fastest strain rates does not vary with OCR and equals about 9%. However, across the three slower rates, increases in OCR cause a consistent decrease in the rate sensitivity that reaches zero at OCR = 8. For high OCR clay, increases in s{sub u} (if they occur) are caused by lower shear-induced pore pressures since the effective stress envelope at the peak strength does not vary with strain rate. For low OCR clay, increases in s{sub u} are caused by both lower shear-induced pore pressures and increases in the mobilized friction angle. A simple technique is proposed for modeling the rate dependent stress-strain curves of over consolidated clay.

  20. Inclination Dependence of Estimated Galaxy Masses and Star Formation Rates

    NASA Astrophysics Data System (ADS)

    Hernandez, Betsy; Maller, Ariyeh; McKernan, Barry; Ford, Saavik

    2016-01-01

    We examine the inclination dependence of inferred star formation rates and galaxy mass estimates in the Sloan Digital Sky Survey by combining the disk/bulge de-convolved catalog of Simard et al 2011 with stellar mass estimates catalog of Mendel et al 2014 and star formation rates measured from spectra by Brinchmann et al 2004. We know that optical star formation indicators are reddened by dust, but calculated star formation rates and stellar mass estimates should account for this. However, we find that face-on galaxies have a higher calculated average star formation rates than edge-on galaxies. We also find edge-on galaxies have ,on average, slightly smaller but similar estimated masses to face-on galaxies, suggesting that there are issues with the applied dust corrections for both models.

  1. Crocodile egg sounds signal hatching time.

    PubMed

    Vergne, Amélie L; Mathevon, Nicolas

    2008-06-24

    Crocodilians are known to vocalize within the egg shortly before hatching [1,2]. Although a possible function of these calls - inducing hatching in siblings and stimulating the adult female to open the nest - has already been suggested, it has never been experimentally tested [1-5]. Here, we present the first experimental evidence that pre-hatching calls of Nile crocodile (Crocodylus niloticus) juveniles are informative acoustic signals which indeed target both siblings and mother. PMID:18579090

  2. Worldwide Spacecraft Crew Hatch History

    NASA Technical Reports Server (NTRS)

    Johnson, Gary

    2009-01-01

    The JSC Flight Safety Office has developed this compilation of historical information on spacecraft crew hatches to assist the Safety Tech Authority in the evaluation and analysis of worldwide spacecraft crew hatch design and performance. The document is prepared by SAIC s Gary Johnson, former NASA JSC S&MA Associate Director for Technical. Mr. Johnson s previous experience brings expert knowledge to assess the relevancy of data presented. He has experience with six (6) of the NASA spacecraft programs that are covered in this document: Apollo; Skylab; Apollo Soyuz Test Project (ASTP), Space Shuttle, ISS and the Shuttle/Mir Program. Mr. Johnson is also intimately familiar with the JSC Design and Procedures Standard, JPR 8080.5, having been one of its original developers. The observations and findings are presented first by country and organized within each country section by program in chronological order of emergence. A host of reference sources used to augment the personal observations and comments of the author are named within the text and/or listed in the reference section of this document. Careful attention to the selection and inclusion of photos, drawings and diagrams is used to give visual association and clarity to the topic areas examined.

  3. Dependence of contamination rates on key parameters in EUV optics

    NASA Astrophysics Data System (ADS)

    Khopkar, Yashdeep; Thomas, Petros; Yankulin, Leonid; Garg, Rashi; Mbanaso, Chimaobi; Antohe, Alin; Upadhyaya, Mihir; Kamineni, Vimal Kumar; Fan, Yu-Jen; Denbeaux, Gregory; Jindal, Vibhu; Wüest, Andrea; Gullikson, Eric

    2011-04-01

    Optics contamination remains one of the challenges in extreme ultraviolet (EUV) lithography. Dependence of contamination rates on key EUV parameters was investigated. EUV tools have optics at different illumination angles. It was observed that at shallower angles, the carbon contamination rate and surface roughness was higher on the optics surface. This is a concern in EUV optics as higher roughness would increase the scattering of the EUV radiation. Secondary ion time of flight mass spectrometer (TOF-SIMS) data indicated that the carbon contamination film might be a polymer. Three chemical species were used to investigate the dependence of polymerization and reactivity on the contamination rate. Acrylic acid was found to have a measurable contamination rate above background compared to propionic acid and methyl methacrylate. Secondary electron dissociation is one of the mechanisms considered to be a cause for the growth of the carbon contamination film. Multiple experiments with two substrates having different secondary electron yields were performed. The substrate with the higher secondary electron yield was found to give a higher contamination rate.

  4. Dose rate dependency of micelle leucodye 3D gel dosimeters

    NASA Astrophysics Data System (ADS)

    Vandecasteele, J.; Ghysel, S.; De Deene, Y.

    2010-11-01

    Recently a novel 3D radiochromic gel dosimeter was introduced which uses micelles to dissolve a leucodye in a gelatin matrix. Experimental results show that this 3D micelle gel dosimeter was found to be dose rate dependent. A maximum difference in optical dose sensitivity of 70% was found for dose rates between 50 cGy min-1 and 400 cGy min-1. A novel composition of 3D radiochromic dosimeter is proposed composed of gelatin, sodium dodecyl sulphate, chloroform, trichloroacetic acid and leucomalachite green. The novel gel dosimeter formulation exhibits comparable radio-physical properties in respect to the composition previously proposed. Nevertheless, the novel formulation was found to be still dose rate dependent. A maximum difference of 33% was found for dose rates between 50 cGy min-1 and 400 cGy min-1. On the basis of these experimental results it is concluded that the leucodye micelle gel dosimeter is still unsatisfactory for clinical radiation therapy dose verifications. Some insights in the physico-chemical mechanisms were obtained and are discussed.

  5. Rate-dependent scaling laws for spall failure

    NASA Astrophysics Data System (ADS)

    Wilkerson, Justin; Ramesh, Kt

    Here we derive simple bounds on the growth rate of voids considering the combined retarding effects of micro-inertia and dislocation kinetics. We make use of these bounds to derive simple scaling laws capable of predicting the strong rate-dependence of spall strength. We show that the rate-sensitivity exponent for spall strength is bounded to below 6/7 when micro-inertia is the dominant retarding effect on void growth. However, under conditions in which the void growth is predominately governed by dislocation kinetics the rate-sensitivity exponent may rise to a maximum value of 1. With these scaling laws in hand, we go on to further explore the role of microstructure on spall strength. Though simple, the derived scaling laws compare well with experimental measurements and prove useful in shedding light on some of the more perplexing observations associated with spall failure. In particular, the scaling laws are helpful in understanding the somewhat anomalous dependence of spall strength on pre-existing microstructure, e.g. grain size and purity content.

  6. Anesthetic Diffusion Through Lipid Membranes Depends on the Protonation Rate

    PubMed Central

    Pérez-Isidoro, Rosendo; Sierra-Valdez, F. J.; Ruiz-Suárez, J. C.

    2014-01-01

    Hundreds of substances possess anesthetic action. However, despite decades of research and tests, a golden rule is required to reconcile the diverse hypothesis behind anesthesia. What makes an anesthetic to be local or general in the first place? The specific targets on proteins, the solubility in lipids, the diffusivity, potency, action time? Here we show that there could be a new player equally or even more important to disentangle the riddle: the protonation rate. Indeed, such rate modulates the diffusion speed of anesthetics into lipid membranes; low protonation rates enhance the diffusion for local anesthetics while high ones reduce it. We show also that there is a pH and membrane phase dependence on the local anesthetic diffusion across multiple lipid bilayers. Based on our findings we incorporate a new clue that may advance our understanding of the anesthetic phenomenon. PMID:25520016

  7. Time-Dependent Behaviors of Granite: Loading-Rate Dependence, Creep, and Relaxation

    NASA Astrophysics Data System (ADS)

    Hashiba, K.; Fukui, K.

    2016-07-01

    To assess the long-term stability of underground structures, it is important to understand the time-dependent behaviors of rocks, such as their loading-rate dependence, creep, and relaxation. However, there have been fewer studies on crystalline rocks than on tuff, mudstone, and rock salt, because the high strength of crystalline rocks makes the detection of their time-dependent behaviors much more difficult. Moreover, studies on the relaxation, temporal change of stress and strain (TCSS) conditions, and relations between various time-dependent behaviors are scarce for not only granites, but also other rocks. In this study, previous reports on the time-dependent behaviors of granites were reviewed and various laboratory tests were conducted using Toki granite. These tests included an alternating-loading-rate test, creep test, relaxation test, and TCSS test. The results showed that the degree of time dependence of Toki granite is similar to other granites, and that the TCSS resembles the stress-relaxation curve and creep-strain curve. A viscoelastic constitutive model, proposed in a previous study, was modified to investigate the relations between the time-dependent behaviors in the pre- and post-peak regions. The modified model reproduced the stress-strain curve, creep, relaxation, and the results of the TCSS test. Based on a comparison of the results of the laboratory tests and numerical simulations, close relations between the time-dependent behaviors were revealed quantitatively.

  8. Dyar's Rule and the Investment Principle: optimal moulting strategies if feeding rate is size-dependent and growth is discontinuous

    PubMed Central

    Hutchinson, J. M. C.; McNamara, J. M.; Houston, A. I.; Vollrath, F.

    1997-01-01

    We consider animals whose feeding rate depends on the size of structures that grow only by moulting (e.g. spiders' legs). Our Investment Principle predicts optimum size increases at each moult; under simplifying assumptions these are a function of the scaling of feeding rate with size, the efficiency of moulting and the optimum size increase at the preceding moult. We show how to test this quantitatively, and make the qualitative prediction that size increases and instar durations change monotonically through development. Thus, this version of the model does not predict that proportional size increases necessarily remain constant, which is the pattern described by Dyar's Rule. A literature survey shows that in nature size increases tend to decline and instar durations to increase, but exceptions to monotonicity occur frequently: we consider how relaxing certain assumptions of the model could explain this. Having specified various functions relating fitness to adult size and time of emergence, we calculate (using dynamic programming) the effect of manipulating food availability, time of hatching and size of the initial (or some intermediate) instar. The associated norms of reaction depend on the fitness function and differ from those when growth follows Dyar's Rule or is continuous. We go on to consider optimization of the number of instars. The Investment Principle then predicts upper and lower limits to observed size increases and explains why increases usually change little or decline through development. This is thus a new adaptive explanation for Dyar's Rule and for the most common deviation from the Rule.

  9. Can Artemia Hatching Assay Be a (Sensitive) Alternative Tool to Acute Toxicity Test?

    PubMed

    Rotini, A; Manfra, L; Canepa, S; Tornambè, A; Migliore, L

    2015-12-01

    Artemia sp. is extensively used in ecotoxicity testing, despite criticisms inherent to both acute and long-term tests. Alternative endpoints and procedures should be considered to support the use of this biological model. The hatching process comprises several developmental steps and the cyst hatchability seems acceptable as endpoint criterion. In this study, we assessed the reliability of the hatching assay on A. franciscana by comparing with acute and long-term mortality tests, using two chemicals: Diethylene Glycol (DEG), Sodium Dodecyl Sulphate (SDS). Both DEG and SDS tests demonstrated a dose dependent hatching inhibition. The hatching test resulted more sensitive than acute mortality test and less sensitive than the long-term one. Results demonstrate the reliability and high sensitivity of this hatching assay on a short time lag and support its useful application in first-tier risk assessment procedures. PMID:26245451

  10. On the Temperature Dependence of Enzyme-Catalyzed Rates.

    PubMed

    Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

    2016-03-29

    One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems. PMID:26881922

  11. 29 CFR 1918.43 - Handling hatch beams and covers.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Handling hatch beams and covers. 1918.43 Section 1918.43... § 1918.43 Handling hatch beams and covers. Paragraphs (f)(2), (g), and (h) of this section apply only to... side of the hatch. (2) On seagoing vessels, hatch boards or similar covers removed from the hatch...

  12. 29 CFR 1918.43 - Handling hatch beams and covers.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Handling hatch beams and covers. 1918.43 Section 1918.43... § 1918.43 Handling hatch beams and covers. Paragraphs (f)(2), (g), and (h) of this section apply only to... side of the hatch. (2) On seagoing vessels, hatch boards or similar covers removed from the hatch...

  13. 29 CFR 1918.43 - Handling hatch beams and covers.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Handling hatch beams and covers. 1918.43 Section 1918.43... § 1918.43 Handling hatch beams and covers. Paragraphs (f)(2), (g), and (h) of this section apply only to... side of the hatch. (2) On seagoing vessels, hatch boards or similar covers removed from the hatch...

  14. 29 CFR 1918.43 - Handling hatch beams and covers.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Handling hatch beams and covers. 1918.43 Section 1918.43... § 1918.43 Handling hatch beams and covers. Paragraphs (f)(2), (g), and (h) of this section apply only to... side of the hatch. (2) On seagoing vessels, hatch boards or similar covers removed from the hatch...

  15. Time dependency of molecular evolutionary rates? Yes and no.

    PubMed

    Subramanian, Sankar; Lambert, David M

    2011-01-01

    Some previous studies have suggested that rates of evolution inferred using molecular sequences vary substantially depending on the time frame over which they are measured, whereas a number of other studies have argued against this proposition. We examined this issue by separating positions of primate mitochondrial genomes that are under different levels of selection constraints. Our results revealed an order of magnitude variation in the evolutionary rates at constrained sites (including nonsynonymous sites, D-loop, and RNA) and virtually an identical rate of evolution at synonymous sites, independent of the timescales over which they were estimated. Although the evolutionary rate at nonsynonymous sites obtained using the European (H1 haplogroup) mitogenomes is 9-15 times higher than that estimated using the human-chimpanzee pair, in contrast, the rates at synonymous sites are similar between these comparisons. We also show that the ratio of divergence at nonsynonymous to synonymous sites estimated using intra- and interspecific comparisons vary up to nine times, which corroborates our results independent of calibration times. PMID:22016336

  16. Time Dependency of Molecular Evolutionary Rates? Yes and No

    PubMed Central

    Subramanian, Sankar; Lambert, David M.

    2011-01-01

    Some previous studies have suggested that rates of evolution inferred using molecular sequences vary substantially depending on the time frame over which they are measured, whereas a number of other studies have argued against this proposition. We examined this issue by separating positions of primate mitochondrial genomes that are under different levels of selection constraints. Our results revealed an order of magnitude variation in the evolutionary rates at constrained sites (including nonsynonymous sites, D-loop, and RNA) and virtually an identical rate of evolution at synonymous sites, independent of the timescales over which they were estimated. Although the evolutionary rate at nonsynonymous sites obtained using the European (H1 haplogroup) mitogenomes is 9–15 times higher than that estimated using the human–chimpanzee pair, in contrast, the rates at synonymous sites are similar between these comparisons. We also show that the ratio of divergence at nonsynonymous to synonymous sites estimated using intra- and interspecific comparisons vary up to nine times, which corroborates our results independent of calibration times. PMID:22016336

  17. Supercontraction forces in spider dragline silk depend on hydration rate.

    PubMed

    Agnarsson, Ingi; Boutry, Cecilia; Wong, Shing-Chung; Baji, Avinash; Dhinojwala, Ali; Sensenig, Andrew T; Blackledge, Todd A

    2009-01-01

    Spider dragline silk is a model biological polymer for biomimetic research due to its many desirable and unusual properties. 'Supercontraction' describes the dramatic shrinking of dragline silk fibers when wetted. In restrained silk fibers, supercontraction generates substantial stresses of 40-50 MPa above a critical humidity of approximately 70% relative humidity (RH). This stress may maintain tension in webs under the weight of rain or dew and could be used in industry for robotics, sensor technology, and other applications. Our own findings indicate that supercontraction can generate stress over a much broader range than previously reported, from 10 to 140 MPa. Here we show that this variation in supercontraction stress depends upon the rate at which the environment reaches the critical level of humidity causing supercontraction. Slow humidity increase, over several minutes, leads to relatively low supercontraction stress, while fast humidity increase, over a few seconds, typically results in higher supercontraction stress. Slowly supercontracted fibers take up less water and differ in thermostability from rapidly supercontracted fibers, as shown by thermogravimetric analysis. This suggests that spider silk achieves different molecular configurations depending upon the speed at which supercontraction occurs. Ultimately, rate-dependent supercontraction may provide a mechanism to tailor the properties of silk or biomimetic fibers for various applications. PMID:19477107

  18. Effect of Methamphetamine Dependence on Heart Rate Variability

    PubMed Central

    Henry, Brook L.; Minassian, Arpi; Perry, William

    2010-01-01

    Background Methamphetamine (METH) is an increasing popular and highly addictive stimulant associated with autonomic nervous system (ANS) dysfunction, cardiovascular pathology, and neurotoxicity. Heart rate variability (HRV) has been used to assess autonomic function and predict mortality in cardiac disorders and drug intoxication, but has not been characterized in METH use. We recorded HRV in a sample of currently abstinent individuals with a history of METH dependence compared to age- and gender-matched drug-free comparison subjects. Method HRV was assessed using time domain, frequency domain, and nonlinear entropic analyses in 17 previously METH-dependent and 21 drug-free comparison individuals during a 5 minute rest period. Results The METH-dependent group demonstrated significant reduction in HRV, reduced parasympathetic activity, and diminished heartbeat complexity relative to comparison participants. More recent METH use was associated with increased sympathetic tone. Conclusion Chronic METH exposure may be associated with decreased HRV, impaired vagal function, and reduction in heart rate complexity as assessed by multiple methods of analysis. We discuss and review evidence that impaired HRV may be related to the cardiotoxic or neurotoxic effects of prolonged METH use. PMID:21182570

  19. Strain rate dependency of oceanic intraplate earthquake b-values at extremely low strain rates

    NASA Astrophysics Data System (ADS)

    Sasajima, Ryohei; Ito, Takeo

    2016-06-01

    We discovered a clear positive dependence of oceanic intraplate earthquake (OCEQ) b-values on the age of the oceanic lithosphere. OCEQ b-values in the youngest (<10 Ma) oceanic lithosphere are around 1.0, while those in middle to old (>20 Ma) oceanic lithosphere exceed 1.5, which is significantly higher than the average worldwide earthquake b-value (around 1.0). On the other hand, the b-value of intraplate earthquakes in the Ninety East-Sumatra orogen, where oceanic lithosphere has an anomalously higher strain rate compared with normal oceanic lithosphere, is 0.93, which is significantly lower than the OCEQ b-value (about 1.9) with the same age (50-110 Ma). Thus, the variation in b-values relates to the strain rate of the oceanic lithosphere and is not caused by a difference in thermal structure. We revealed a negative strain rate dependency of the b-value at extremely low strain rates (<2 × 10-10/year), which can clearly explain the above b-values. We propose that the OCEQ b-value depends strongly on strain rate (either directly or indirectly) at extremely low strain rates. The high OCEQ b-values (>1.5) in oceanic lithosphere >20 Ma old imply that future improvement in seismic observation will capture many smaller magnitude OCEQs, which will provide valuable information on the evolution of the oceanic lithosphere and the driving mechanism of plate tectonics.

  20. 9 CFR 91.29 - Hatches.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION... placed on hatches on exposed decks on an ocean vessel if the pens or stalls are securely lashed down. (b) Animals may be placed on hatches on underdecks on an ocean vessel provided the height requirements of §...

  1. Shuttle Crew Says Farewell, Closes Hatches

    NASA Video Gallery

    At 7:23 a.m. Sunday, hatches were closed between Endeavour and the station 12 days, 22 hours and 27 minutes into the mission. The hatches between the two spacecraft were opened at 7:38 a.m. on May ...

  2. 29 CFR 1918.35 - Open hatches.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR LONGSHORING Working Surfaces § 1918.35 Open hatches. Open weather deck hatches around which employees must work that are not protected to a height of 24 inches (.61 m)...

  3. Stress state and strain rate dependence of the human placenta.

    PubMed

    Weed, Benjamin C; Borazjani, Ali; Patnaik, Sourav S; Prabhu, R; Horstemeyer, M F; Ryan, Peter L; Franz, Thomas; Williams, Lakiesha N; Liao, Jun

    2012-10-01

    Maternal trauma (MT) in automotive collisions is a source of injury, morbidity, and mortality for both mothers and fetuses. The primary associated pathology is placental abruption in which the placenta detaches from the uterus leading to hemorrhaging and termination of pregnancy. In this study, we focused on the differences in placental tissue response to different stress states (tension, compression, and shear) and different strain rates. Human placentas were obtained (n = 11) for mechanical testing and microstructure analysis. Specimens (n = 4+) were tested in compression, tension, and shear, each at three strain rates (nine testing protocols). Microstructure analysis included scanning electron microscopy, histology, and interrupted mechanical tests to observe tissue response to various loading states. Our data showed the greatest stiffness in tension, followed by compression, and then by shear. The study concludes that mechanical behavior of human placenta tissue (i) has a strong stress state dependence and (ii) behaves in a rate dependent manner in all three stress states, which had previously only been shown in tension. Interrupted mechanical tests revealed differences in the morphological microstructure evolution that was driven by the kinematic constraints from the different loading states. Furthermore, these structure-property data can be used to develop high fidelity constitutive models for MT simulations. PMID:22581478

  4. Correcting the NICMOS count-rate dependent non-linearity

    NASA Astrophysics Data System (ADS)

    de Jong, Roelof S.

    2006-03-01

    We describe a routine to correct NICMOS imaging data for the NICMOS count-rate dependent non-linearity recently discovered by Bohlin et al. (2005) and quantified by deJong et al. (2006) and Bohlin et al. (2006). The routine has been implemented in the python scripting language and is callable from the shell command line and from iraf. The routine corrects NICMOS count-rate images assuming the non-linearity follows a powerlaw behavior. The wavelength dependence of the non-linearity is interpolated between the measured points of de Jong et al. (2006) and Bohlin et al. (2006) if necessary. The count rates in the output images are modified and hence the standard NICMOS calibration zero-points are no longer valid. New calibration zero-points have been derived from standard star images corrected with the routine. The routine was tested on the lamp-on/off data used in de Jong et al. (2006) to measure the non-linearity effect. We apply the correction to the NGC1850 stellar cluster field and the Hubble Ultra Deep Field (HUDF) to show the magnitude offsets expected due to the non-linearity on objects with a range in luminosity and surface brightness.

  5. Rate-Dependence in the Shearing of Slow Granular Material

    NASA Astrophysics Data System (ADS)

    Hartley, Robert; Behringer, Robert

    2002-03-01

    It is generally assumed, that sheared granular (Coulomb) materials exhibit rate independence of stresses, for slow enough rates. We have carried out sensitive tests of this assumption using a 2D granular Couette experiment (c.f. Howell et al.)(D. Howell, et al. Phys. Rev. Lett. 82), 5241 (1999). Flat photoelastic particles with a pentagonal footprint, lying on a smooth flat surface, are are subjet to steady shearing. We measure the stress, σ, summed over about 200 particles, i.e. about 10% of the total sample. σ is a strong funtion of time due to the making and breaking of force chains. Long time time series, σ(t) were acquired for inner wheel rotation frequencies, f between 0.03 mHz and 70 mHz. It is immediately obvious from the time series of these data that the stresses relax towards a flat background at low frequency, but not at the higher frequencies. Both the distributions for σ and the means <σ (f)> depend on f. In particular, the variation of <σ (f)> with f is well described by <σ (f)> = A log(f/f_o) where the inverse of the constant fo is of order 10's of days. Logarithmic rate dependence is consistent with recent compaction experiments by Novak et al.(E. R. Novak et al. Phys. Rev. E 57), 1971 (1998). and piston experiments by Overlez et al.(G. Overlez et al. to appear, Phys. Rev. E.)

  6. Prevalence of Rate-Dependent Behaviors in Cardiac Muscle

    NASA Astrophysics Data System (ADS)

    Hall, G. Martin; Bahar, Sonya; Gauthier, Daniel J.

    1999-04-01

    We explore the rate-dependent dynamic response of periodically paced bullfrog (Rana catesbeiana) cardiac muscle. Alternans (2:2 behavior) occur in 35% of animals and 2:1<-->1:1 bistability in 74% of animals. In addition, we observe 2:2<-->2:1 bistablility. We discuss the implications of these results for two map-based models of cardiac dynamics. The high prevalence of bistability suggests that this dynamical behavior must be accounted for in the design of closed-loop feedback protocols to stabilize cardiac dynamics.

  7. Temperature and strain-rate dependence of surface dislocation nucleation.

    PubMed

    Zhu, Ting; Li, Ju; Samanta, Amit; Leach, Austin; Gall, Ken

    2008-01-18

    Dislocation nucleation is essential to the plastic deformation of small-volume crystalline solids. The free surface may act as an effective source of dislocations to initiate and sustain plastic flow, in conjunction with bulk sources. Here, we develop an atomistic modeling framework to address the probabilistic nature of surface dislocation nucleation. We show the activation volume associated with surface dislocation nucleation is characteristically in the range of 1-10b3, where b is the Burgers vector. Such small activation volume leads to sensitive temperature and strain-rate dependence of the nucleation stress, providing an upper bound to the size-strength relation in nanopillar compression experiments. PMID:18232884

  8. Position dependent rate dampening in any active hand controller

    NASA Technical Reports Server (NTRS)

    Gregory, William W. (Inventor); Kauffman, James W. (Inventor)

    1994-01-01

    A control system for an active hand controller, for example, uses a control stick connected to and controlled by a motor. Electronics are provided to control the motor to eliminate oscillations due to motor torque and high gain due to breakout at the control stick when the control stick is at about its null position. Both hardware as well as software implementations can provide position dependent dampening to the control sticks such that when the control stick is located about a null position, a higher rate of dampening is provided than when the control stick is located outside the null position, when a lower rate of dampening is provided. The system provides a stable active hand controller control stick without degraded force and feel characteristics of the system.

  9. Culture, feeding, and growth of alewives hatched in the laboratory

    USGS Publications Warehouse

    Heinrich, John W.

    1981-01-01

    Alewives (Alosa pseudoharengus) were reared from the egg to the early juvenile life stage. The major obstacle to rearing alewives from the egg- providing an acceptable food that facilitates first feeding- was overcome by presenting a mixture of wild zooplankton to the larvae twice daily, beginning on the day of hatching. Initial feeding by larvae held at 20A?C was observed 2 days after hatching, when the yolk was nearly absorbed. Comparison of stomach contents and the wild zooplankton composition suggested that the diet of larvae during the first 15 days of life shifted with changes in the availability of food but remained within a fairly narrow range of food sizes. Larvae hatched at a mean total length of 3.8 mm and grew at an average rate of 0.62 mm per day, to a mean of 35.5 mm after 50 days. At 50 days most fish had transformed into juveniles. The daily instantaneous mortality coefficient was 0.018. About half of the mortality occurred during the first 13 days after hatching.

  10. Scale dependence of rock friction at high work rate.

    PubMed

    Yamashita, Futoshi; Fukuyama, Eiichi; Mizoguchi, Kazuo; Takizawa, Shigeru; Xu, Shiqing; Kawakata, Hironori

    2015-12-10

    Determination of the frictional properties of rocks is crucial for an understanding of earthquake mechanics, because most earthquakes are caused by frictional sliding along faults. Prior studies using rotary shear apparatus revealed a marked decrease in frictional strength, which can cause a large stress drop and strong shaking, with increasing slip rate and increasing work rate. (The mechanical work rate per unit area equals the product of the shear stress and the slip rate.) However, those important findings were obtained in experiments using rock specimens with dimensions of only several centimetres, which are much smaller than the dimensions of a natural fault (of the order of 1,000 metres). Here we use a large-scale biaxial friction apparatus with metre-sized rock specimens to investigate scale-dependent rock friction. The experiments show that rock friction in metre-sized rock specimens starts to decrease at a work rate that is one order of magnitude smaller than that in centimetre-sized rock specimens. Mechanical, visual and material observations suggest that slip-evolved stress heterogeneity on the fault accounts for the difference. On the basis of these observations, we propose that stress-concentrated areas exist in which frictional slip produces more wear materials (gouge) than in areas outside, resulting in further stress concentrations at these areas. Shear stress on the fault is primarily sustained by stress-concentrated areas that undergo a high work rate, so those areas should weaken rapidly and cause the macroscopic frictional strength to decrease abruptly. To verify this idea, we conducted numerical simulations assuming that local friction follows the frictional properties observed on centimetre-sized rock specimens. The simulations reproduced the macroscopic frictional properties observed on the metre-sized rock specimens. Given that localized stress concentrations commonly occur naturally, our results suggest that a natural fault may lose its

  11. Scale dependence of rock friction at high work rate

    NASA Astrophysics Data System (ADS)

    Yamashita, Futoshi; Fukuyama, Eiichi; Mizoguchi, Kazuo; Takizawa, Shigeru; Xu, Shiqing; Kawakata, Hironori

    2015-12-01

    Determination of the frictional properties of rocks is crucial for an understanding of earthquake mechanics, because most earthquakes are caused by frictional sliding along faults. Prior studies using rotary shear apparatus revealed a marked decrease in frictional strength, which can cause a large stress drop and strong shaking, with increasing slip rate and increasing work rate. (The mechanical work rate per unit area equals the product of the shear stress and the slip rate.) However, those important findings were obtained in experiments using rock specimens with dimensions of only several centimetres, which are much smaller than the dimensions of a natural fault (of the order of 1,000 metres). Here we use a large-scale biaxial friction apparatus with metre-sized rock specimens to investigate scale-dependent rock friction. The experiments show that rock friction in metre-sized rock specimens starts to decrease at a work rate that is one order of magnitude smaller than that in centimetre-sized rock specimens. Mechanical, visual and material observations suggest that slip-evolved stress heterogeneity on the fault accounts for the difference. On the basis of these observations, we propose that stress-concentrated areas exist in which frictional slip produces more wear materials (gouge) than in areas outside, resulting in further stress concentrations at these areas. Shear stress on the fault is primarily sustained by stress-concentrated areas that undergo a high work rate, so those areas should weaken rapidly and cause the macroscopic frictional strength to decrease abruptly. To verify this idea, we conducted numerical simulations assuming that local friction follows the frictional properties observed on centimetre-sized rock specimens. The simulations reproduced the macroscopic frictional properties observed on the metre-sized rock specimens. Given that localized stress concentrations commonly occur naturally, our results suggest that a natural fault may lose its

  12. Temperature dependences of rate coefficients for electron catalyzed mutual neutralization

    SciTech Connect

    Shuman, Nicholas S.; Miller, Thomas M.; Friedman, Jeffrey F.; Viggiano, Albert A.; Maeda, Satoshi; Morokuma, Keiji

    2011-07-14

    The flowing afterglow technique of variable electron and neutral density attachment mass spectrometry (VENDAMS) has recently yielded evidence for a novel plasma charge loss process, electron catalyzed mutual neutralization (ECMN), i.e., A{sup +}+ B{sup -}+ e{sup -}{yields} A + B + e{sup -}. Here, rate constants for ECMN of two polyatomic species (POCl{sub 3}{sup -} and POCl{sub 2}{sup -}) and one diatomic species (Br{sub 2}{sup -}) each with two monatomic cations (Ar{sup +}and Kr{sup +}) are measured using VENDAMS over the temperature range 300 K-500 K. All rate constants show a steep negative temperature dependence, consistent with that expected for a three body process involving two ions and an electron. No variation in rate constants as a function of the cation type is observed outside of uncertainty; however, rate constants of the polyatomic anions ({approx}1 x 10{sup -18} cm{sup 6} s{sup -1} at 300 K) are measurably higher than that for Br{sub 2}{sup -}[(5.5 {+-} 2) x 10{sup -19} cm{sup 6} s{sup -1} at 300 K].

  13. Interpretation of the temperature dependence of equilibrium and rate constants.

    PubMed

    Winzor, Donald J; Jackson, Craig M

    2006-01-01

    The objective of this review is to draw attention to potential pitfalls in attempts to glean mechanistic information from the magnitudes of standard enthalpies and entropies derived from the temperature dependence of equilibrium and rate constants for protein interactions. Problems arise because the minimalist model that suffices to describe the energy differences between initial and final states usually comprises a set of linked equilibria, each of which is characterized by its own energetics. For example, because the overall standard enthalpy is a composite of those individual values, a positive magnitude for DeltaH(o) can still arise despite all reactions within the subset being characterized by negative enthalpy changes: designation of the reaction as being entropy driven is thus equivocal. An experimenter must always bear in mind the fact that any mechanistic interpretation of the magnitudes of thermodynamic parameters refers to the reaction model rather than the experimental system. For the same reason there is little point in subjecting the temperature dependence of rate constants for protein interactions to transition-state analysis. If comparisons with reported values of standard enthalpy and entropy of activation are needed, they are readily calculated from the empirical Arrhenius parameters. PMID:16897812

  14. Acute and chronic eggshell temperature manipulations during hatching term influence hatchability, broiler performance, and ascites incidence.

    PubMed

    Sozcu, A; Ipek, A

    2015-02-01

    The aim of the current study was to determine how a control temperature and acute and chronic high eggshell temperatures during the last three days of incubation, can affect hatchability, chick quality, and organ development on day of hatch as well as broiler performance and ascites incidence in later life. The eggshell temperature manipulations were applied during hatching term (days 19 to 21) as follows: control EST (37.3 to 38.0°C), acute high eggshell temperature manipulations (38.4- to 39.0°C for three hours daily) and chronic high eggshell temperature manipulations (38.4 to 39.0°C). The lowest hatchability and the highest cull chick rate were in the chronic high eggshell temperature manipulations group. Lower chick quality parameters correlated with lower chick weights and heavier residual yolk sac weights that were in the chronic high eggshell temperature manipulations group depending on hatch time. The live weights on the 1(st) day of the growing period were higher in the control and acute high eggshell temperature manipulations groups than the chronic high eggshell temperature manipulations group. At 6 wk of age, live weights of broilers were the highest in the control than in the acute and chronic high eggshell temperature manipulations groups. The total mortality was 2.5, 9.2, and 13.3%, the mortality due to ascites was 2.1, 8.3, and 12.9% in the control, acute ,and chronic high eggshell temperature manipulations groups, respectively. The right ventricular/total ventricular ratios for the control, acute and chronic high eggshell temperature manipulations groups were 0.22, 0.28, and 0.30%, respectively. In conclusion, short-term and long-term higher temperatures during the hatching term affect embryo development, incubation results, broiler performance, and ascites incidence. Although the acute high eggshell temperature manipulations did not affect the chick quality parameters at hatch, it negatively affected incubation results and broiler performance

  15. Concentration dependence of variability in growth rates of microtubules.

    PubMed Central

    Pedigo, Susan; Williams, Robley C

    2002-01-01

    Growth and shortening of microtubules in the course of their polymerization and depolymerization have previously been observed to occur at variable rates. To gain insight into the meaning of this prominent variability, we studied the way in which its magnitude depends on the growth rate of experimentally observed and computer-simulated microtubules. The dynamic properties of plus-ended microtubules nucleated by pieces of Chlamydomonas flagellar axonemes were observed in real time by video-enhanced differential interference contrast light microscopy at differing tubulin concentrations. By means of a Monte Carlo algorithm, populations of microtubules were simulated that had similar growth and dynamic properties to the experimentally observed microtubules. By comparison of the experimentally observed and computer-simulated populations of microtubules, we found that 1) individual microtubules displayed an intrinsic variability that did not change as the rate of growth for a population increased, and 2) the variability was approximately fivefold greater than predicted by a simple model of subunit addition and loss. The model used to simulate microtubule growth has no provision for incorporation of lattice defects of any type, nor sophisticated geometry of the growing end. Thus, these as well as uncontrolled experimental variables were eliminated as causes for the prominent variability. PMID:12324403

  16. Fuel transfer tube quick opening hatch

    SciTech Connect

    Meuschke, R. E.; Sherwood, D. G.; Silverblatt, B. L.

    1985-05-28

    A quick opening hatch for use on a transfer tube of a nuclear reactor plant that is adapted to replace the conventional hatch on the transfer tube. A locking ring is provided with a plurality of screw openings that is adapted for connection to the transfer tube, and a hatch cover fitably received within the locking ring for closing-off the transfer tube. To lock the cover to the ring, latches are movably connected with the cover for locking engagement with the locking ring, and a sprocket with a plurality of crank arms is movably connected with the cover and the latches for movement thereof into locking engagement with a latch housing on the locking ring for locking the cover to the ring and out of engagement with the latch housing for releasing the cover from the locking ring so as to permit removal of the hatch cover from the locking ring to provide access to the transfer tube. A davit assembly is provided which is connected with the transfer tube and the hatch cover to move the cover away and to provide guidance for closing-off the transfer tube. The locking ring and hatch cover also include cooperating keys and keyways for alignment when closing the transfer tube. The cover is provided with sealing rings and the latch housing and latches include cooperating cam surfaces to provide a tight locking engagement by compressing the sealing rings between the transfer tube and the hatch cover.

  17. Safety Considerations in Design of Spacecraft Hatches

    NASA Astrophysics Data System (ADS)

    Ciancone, Michael L.; Johnson, Gary W.

    2010-09-01

    Human spaceflight missions have grown longer and more complex as international spaceflight programs have evolved. This has presented additional safety considerations in the design of hatches for habitable spacecraft. One important decision in the design of spacecraft is whether to use pressure-sealing hatches that open inward(i.e., internal cabin pressure keeps the hatch sealed on orbit) or hatches that open outward(i.e., facilitates crew egress during pre-launch and post-landing events). This paper will explore safety considerations that influence that decision, as well as hazards associated with hatches. Safety considerations include mission duration, mission profile(relatively short sorties to ISS versus extended journeys to the Moon or planets), intended usage(e.g., flight and ground crew ingress/egress during ground phases, flight crew ingress/egress during EVA, or inter-spacecraft access during docked operations), reliability/complexity(usually involving mechanisms and/or pyrotechnics), and off-nominal ground ingress/egress(how many crew members must egress within a specified length of time under what circumstances). In addition, this paper will provide a historical survey of hatch designs for manned spacecraft, including a brief list of incidents involving hatches.

  18. Temperature-mediated survival, development and hatching variation of Pacific cod Gadus macrocephalus eggs.

    PubMed

    Bian, X; Zhang, X; Sakrai, Y; Jin, X; Gao, T; Wan, R; Yamamoto, J

    2014-01-01

    Laboratory-validated data on the survival, development and hatching responses of fertilized Pacific cod Gadus macrocephalus eggs from the northern Japan stock were determined through an incubation experiment. The optimum temperature for survival until hatching ranged from 4 to 8°C. No significant difference in development rates was found between the populations from Mutsu Bay, Japan, and western Canadian coastal waters even though the samples may belong to different G. macrocephalus stocks. Gadus macrocephalus larvae hatched asynchronously from egg batches despite incubation under the same environment during their development. Both incubation temperature and temperature-mediated hatch rank affect size and yolk reserve. These data suggest that variations in water temperatures within an ecological range markedly influence the development rates, survival and hatching of the eggs, as well as the stage at hatch larvae of G. macrocephalus. Asynchronous hatching and the production of offspring with variable sizes and yolk reserves are considered evolutionary bet-hedging strategies that enable the species to maximize their likelihood of survival in an environment with variable temperatures. PMID:24344879

  19. Cruciate thinning of the zona pellucida for more successful enhancement of blastocyst hatching in the mouse.

    PubMed

    Khalifa, E A; Tucker, M J; Hunt, P

    1992-04-01

    Implantation rates remain low following human in-vitro fertilization (IVF). Suboptimal culture conditions may limit the ability of embryos to hatch as blastocysts, and artificial opening of the zona pellucida has been proposed as a means to promote subsequent hatching (assisted hatching). Such techniques must have minimal adverse effects on the embryos, while maximizing the potential for an embryo to hatch fully as a blastocyst. In a mouse model, we compared embryonic development after zona drilling, and cruciate thinning of the zona (CTOZ) intended to simulate the natural thinning of the zona pellucida. Using acidic Tyrode's solution both zona drilling and cruciate-thinning were performed on day 3 morulae. On day 4 the rates of complete hatching of blastocysts were 0/165, 24/172 and 72/175 in control, zona drilled and thinned groups respectively (P less than 0.0001). On day 5 the rates of complete hatching in the same groups were 20/165, 54/172 and 120/175 respectively (P less than 0.00001) and by day 6, 66/165, 74/172 and 130/175 respectively (P less than 0.00001). The rate of arrest at the morula stage was 24/172 versus 8/175 in the zona drilled and thinned groups respectively (P less than 0.005, whilst the rate of arrest at the blastocyst stage was 21/172 versus 14/175 respectively (NS). Hence cruciate thinning of the zona appears less detrimental at the morula stage than zona drilling, but eventual rates of arrest at the blastocyst stage were comparable. Both techniques significantly increased the rate of hatching, but zona drilling did not guarantee complete hatching.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1522198

  20. Potential pitfalls of strain rate imaging: angle dependency

    NASA Technical Reports Server (NTRS)

    Castro, P. L.; Greenberg, N. L.; Drinko, J.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    Strain Rate Imaging (SRI) is a new echocardiographic technique that allows for the real-time determination of myocardial SR, which may be used for the early and accurate detection of coronary artery disease. We sought to study whether SR is affected by scan line alignment in a computer simulation and an in vivo experiment. Through the computer simulation and the in vivo experiment we generated and validated safe scanning sectors within the ultrasound scan sector and showed that while SRI will be an extremely valuable tool in detecting coronary artery disease there are potential pitfalls for the unwary clinician. Only after accounting for these affects due to angle dependency, can clinicians utilize SRI's potential as a valuable tool in detecting coronary artery disease.

  1. Characterizing heart rate variability by scale-dependent Lyapunov exponent

    NASA Astrophysics Data System (ADS)

    Hu, Jing; Gao, Jianbo; Tung, Wen-wen

    2009-06-01

    Previous studies on heart rate variability (HRV) using chaos theory, fractal scaling analysis, and many other methods, while fruitful in many aspects, have produced much confusion in the literature. Especially the issue of whether normal HRV is chaotic or stochastic remains highly controversial. Here, we employ a new multiscale complexity measure, the scale-dependent Lyapunov exponent (SDLE), to characterize HRV. SDLE has been shown to readily characterize major models of complex time series including deterministic chaos, noisy chaos, stochastic oscillations, random 1/f processes, random Levy processes, and complex time series with multiple scaling behaviors. Here we use SDLE to characterize the relative importance of nonlinear, chaotic, and stochastic dynamics in HRV of healthy, congestive heart failure, and atrial fibrillation subjects. We show that while HRV data of all these three types are mostly stochastic, the stochasticity is different among the three groups.

  2. On the context-dependent scaling of consumer feeding rates.

    PubMed

    Barrios-O'Neill, Daniel; Kelly, Ruth; Dick, Jaimie T A; Ricciardi, Anthony; MacIsaac, Hugh J; Emmerson, Mark C

    2016-06-01

    The stability of consumer-resource systems can depend on the form of feeding interactions (i.e. functional responses). Size-based models predict interactions - and thus stability - based on consumer-resource size ratios. However, little is known about how interaction contexts (e.g. simple or complex habitats) might alter scaling relationships. Addressing this, we experimentally measured interactions between a large size range of aquatic predators (4-6400 mg over 1347 feeding trials) and an invasive prey that transitions among habitats: from the water column (3D interactions) to simple and complex benthic substrates (2D interactions). Simple and complex substrates mediated successive reductions in capture rates - particularly around the unimodal optimum - and promoted prey population stability in model simulations. Many real consumer-resource systems transition between 2D and 3D interactions, and along complexity gradients. Thus, Context-Dependent Scaling (CDS) of feeding interactions could represent an unrecognised aspect of food webs, and quantifying the extent of CDS might enhance predictive ecology. PMID:27094829

  3. A Stellar-mass-dependent Drop in Planet Occurrence Rates

    NASA Astrophysics Data System (ADS)

    Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

    2015-01-01

    The Kepler spacecraft has discovered a large number of planets with up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with effective temperatures as low as 2500 K, which corresponds to M stars. These cooler stars allow characterization of small planets near the habitable zone, yet it is not clear if this population is representative of that around FGK stars. In this paper, we calculate the occurrence of planets around stars of different spectral types as a function of planet radius and distance from the star and show that they are significantly different from each other. We further identify two trends. First, the occurrence of Earth- to Neptune-sized planets (1-4 R ⊕) is successively higher toward later spectral types at all orbital periods probed by Kepler; planets around M stars occur twice as frequently as around G stars, and thrice as frequently as around F stars. Second, a drop in planet occurrence is evident at all spectral types inward of a ~10 day orbital period, with a plateau further out. By assigning to each spectral type a median stellar mass, we show that the distance from the star where this drop occurs is stellar mass dependent, and scales with semi-major axis as the cube root of stellar mass. By comparing different mechanisms of planet formation, trapping, and destruction, we find that this scaling best matches the location of the pre-main-sequence co-rotation radius, indicating efficient trapping of migrating planets or planetary building blocks close to the star. These results demonstrate the stellar-mass dependence of the planet population, both in terms of occurrence rate and of orbital distribution. The prominent stellar-mass dependence of the inner boundary of the planet population shows that the formation or migration of planets is sensitive to the stellar parameters.

  4. A STELLAR-MASS-DEPENDENT DROP IN PLANET OCCURRENCE RATES

    SciTech Connect

    Mulders, Gijs D.; Pascucci, Ilaria; Apai, Dániel

    2015-01-10

    The Kepler spacecraft has discovered a large number of planets with up to one-year periods and down to terrestrial sizes. While the majority of the target stars are main-sequence dwarfs of spectral type F, G, and K, Kepler covers stars with effective temperatures as low as 2500 K, which corresponds to M stars. These cooler stars allow characterization of small planets near the habitable zone, yet it is not clear if this population is representative of that around FGK stars. In this paper, we calculate the occurrence of planets around stars of different spectral types as a function of planet radius and distance from the star and show that they are significantly different from each other. We further identify two trends. First, the occurrence of Earth- to Neptune-sized planets (1-4 R {sub ⊕}) is successively higher toward later spectral types at all orbital periods probed by Kepler; planets around M stars occur twice as frequently as around G stars, and thrice as frequently as around F stars. Second, a drop in planet occurrence is evident at all spectral types inward of a ∼10 day orbital period, with a plateau further out. By assigning to each spectral type a median stellar mass, we show that the distance from the star where this drop occurs is stellar mass dependent, and scales with semi-major axis as the cube root of stellar mass. By comparing different mechanisms of planet formation, trapping, and destruction, we find that this scaling best matches the location of the pre-main-sequence co-rotation radius, indicating efficient trapping of migrating planets or planetary building blocks close to the star. These results demonstrate the stellar-mass dependence of the planet population, both in terms of occurrence rate and of orbital distribution. The prominent stellar-mass dependence of the inner boundary of the planet population shows that the formation or migration of planets is sensitive to the stellar parameters.

  5. Assessing Wind Farm Reliability Using Weather Dependent Failure Rates

    NASA Astrophysics Data System (ADS)

    Wilson, G.; McMillan, D.

    2014-06-01

    Using reliability data comprising of two modern, large scale wind farm sites and wind data from two onsite met masts, a model is developed which calculates wind speed dependant failure rates which are used to populate a Markov Chain. Monte Carlo simulation is then exercised to simulate three wind farms which are subjected to controlled wind speed conditions from three separate potential UK sites. The model then calculates and compares wind farm reliability due to corrective maintenance and component failure rates influenced by the wind speed of each of the sites. Results show that the components affected most by changes in average daily wind speed are the control system and the yaw system. A comparison between this model and a more simple estimation of site yield is undertaken. The model takes into account the effects of the wind speed on the cost of operation and maintenance and also includes the impact of longer periods of downtime in the winter months and shorter periods in the summer. By taking these factors into account a more detailed site assessment can be undertaken. There is significant value to this model for operators and manufacturers.

  6. Interpreting the Dependence of Mutation Rates on Age and Time

    PubMed Central

    Gao, Ziyue; Wyman, Minyoung J.; Sella, Guy; Przeworski, Molly

    2016-01-01

    Mutations can originate from the chance misincorporation of nucleotides during DNA replication or from DNA lesions that arise between replication cycles and are not repaired correctly. We introduce a model that relates the source of mutations to their accumulation with cell divisions, providing a framework for understanding how mutation rates depend on sex, age, and cell division rate. We show that the accrual of mutations should track cell divisions not only when mutations are replicative in origin but also when they are non-replicative and repaired efficiently. One implication is that observations from diverse fields that to date have been interpreted as pointing to a replicative origin of most mutations could instead reflect the accumulation of mutations arising from endogenous reactions or exogenous mutagens. We further find that only mutations that arise from inefficiently repaired lesions will accrue according to absolute time; thus, unless life history traits co-vary, the phylogenetic “molecular clock” should not be expected to run steadily across species. PMID:26761240

  7. DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes.

    PubMed

    Kadibalban, A Samer; Bogumil, David; Landan, Giddy; Dagan, Tal

    2016-01-01

    Many proteins depend on an interaction with molecular chaperones in order to fold into a functional tertiary structure. Previous studies showed that protein interaction with the GroEL/GroES chaperonine and Hsp90 chaperone can buffer the impact of slightly deleterious mutations in the protein sequence. This capacity of GroEL/GroES to prevent protein misfolding has been shown to accelerate the evolution of its client proteins. Whether other bacterial chaperones have a similar effect on their client proteins is currently unknown. Here, we study the impact of DnaK (Hsp70) chaperone on the evolution of its client proteins. Evolutionary parameters were derived from comparison of the Escherichia coli proteome to 1,808,565 orthologous proteins in 1,149 proteobacterial genomes. Our analysis reveals a significant positive correlation between protein binding frequency with DnaK and evolutionary rate. Proteins with high binding affinity to DnaK evolve on average 4.3-fold faster than proteins in the lowest binding affinity class at the genus resolution. Differences in evolutionary rates of DnaK interactor classes are still significant after adjusting for possible effects caused by protein expression level. Furthermore, we observe an additive effect of DnaK and GroEL chaperones on the evolutionary rates of their common interactors. Finally, we found pronounced similarities in the physicochemical profiles that characterize proteins belonging to DnaK and GroEL interactomes. Our results thus implicate DnaK-mediated folding as a major component in shaping protein evolutionary dynamics in bacteria and supply further evidence for the long-term manifestation of chaperone-mediated folding on genome evolution. PMID:27189986

  8. DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes

    PubMed Central

    Kadibalban, A. Samer; Bogumil, David; Landan, Giddy; Dagan, Tal

    2016-01-01

    Many proteins depend on an interaction with molecular chaperones in order to fold into a functional tertiary structure. Previous studies showed that protein interaction with the GroEL/GroES chaperonine and Hsp90 chaperone can buffer the impact of slightly deleterious mutations in the protein sequence. This capacity of GroEL/GroES to prevent protein misfolding has been shown to accelerate the evolution of its client proteins. Whether other bacterial chaperones have a similar effect on their client proteins is currently unknown. Here, we study the impact of DnaK (Hsp70) chaperone on the evolution of its client proteins. Evolutionary parameters were derived from comparison of the Escherichia coli proteome to 1,808,565 orthologous proteins in 1,149 proteobacterial genomes. Our analysis reveals a significant positive correlation between protein binding frequency with DnaK and evolutionary rate. Proteins with high binding affinity to DnaK evolve on average 4.3-fold faster than proteins in the lowest binding affinity class at the genus resolution. Differences in evolutionary rates of DnaK interactor classes are still significant after adjusting for possible effects caused by protein expression level. Furthermore, we observe an additive effect of DnaK and GroEL chaperones on the evolutionary rates of their common interactors. Finally, we found pronounced similarities in the physicochemical profiles that characterize proteins belonging to DnaK and GroEL interactomes. Our results thus implicate DnaK-mediated folding as a major component in shaping protein evolutionary dynamics in bacteria and supply further evidence for the long-term manifestation of chaperone-mediated folding on genome evolution. PMID:27189986

  9. Hatches Open, Expedition 32 Expands to Six

    NASA Video Gallery

    The hatches between the Soyuz and the Rassvet module opened Tuesday at 3:23 a.m. when Flight Engineers Suni Williams, Yuri Malenchenko and Aki Hoshide entered the International Space Station. Exped...

  10. Expedition 28 Farewell and Hatch Closure

    NASA Video Gallery

    The hatches between the Soyuz TMA-21 spacecraft and the International Space Station were closed at 5:30 p.m. EDT Thursday, Sept. 15 wrapping up 162 days aboard the orbiting outpost for Expedition 2...

  11. Hatching asynchrony aggravates inbreeding depression in a songbird (Serinus canaria): an inbreeding-environment interaction.

    PubMed

    de Boer, Raïssa A; Eens, Marcel; Fransen, Erik; Müller, Wendt

    2015-04-01

    Understanding how the intensity of inbreeding depression is influenced by stressful environmental conditions is an important area of enquiry in various fields of biology. In birds, environmental stress during early development is often related to hatching asynchrony; differences in age, and thus size, impose a gradient in conditions ranging from benign (first hatched chick) to harsh (last hatched chick). Here, we compared the effect of hatching order on growth rate in inbred (parents are full siblings) and outbred (parents are unrelated) canary chicks (Serinus canaria). We found that inbreeding depression was more severe under more stressful conditions, being most evident in later hatched chicks. Thus, consideration of inbreeding-environment interactions is of vital importance for our understanding of the biological significance of inbreeding depression and hatching asynchrony. The latter is particularly relevant given that hatching asynchrony is a widespread phenomenon, occurring in many bird species. The exact causes of the observed inbreeding-environment interaction are as yet unknown, but may be related to a decrease in maternal investment in egg contents with laying position (i.e. prehatching environment), or to performance of the chicks during sibling competition and/or their resilience to food shortage (i.e. posthatching environment). PMID:25689753

  12. Induced nest spawning and artificial hatching of the fertilized eggs of mudskipper, Boleophthalmus pectinirostris

    NASA Astrophysics Data System (ADS)

    Hong, Wanshu; Zhang, Qiyong

    2004-12-01

    In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper, Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of the nest-spawned eggs varied from 17.3% to 80.8%. Females could spawn after being artificially confined inside the nests with males at ratios of 1∶1 or 1∶2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs incubated in round plastic buckets were 32.7% 70.6%, and in the net cages, were 4.2% 20.5%, respectively. Mean hatching rates of nest-fertilized eggs incubated in the round plastic buckets were 33.6% 76.3%, and in the net cages, were 5.9% 25.2%. Results showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper. Keeping the hatching seawater flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs.

  13. Spreading rate dependence of gravity anomalies along oceanic transform faults.

    PubMed

    Gregg, Patricia M; Lin, Jian; Behn, Mark D; Montési, Laurent G J

    2007-07-12

    Mid-ocean ridge morphology and crustal accretion are known to depend on the spreading rate of the ridge. Slow-spreading mid-ocean-ridge segments exhibit significant crustal thinning towards transform and non-transform offsets, which is thought to arise from a three-dimensional process of buoyant mantle upwelling and melt migration focused beneath the centres of ridge segments. In contrast, fast-spreading mid-ocean ridges are characterized by smaller, segment-scale variations in crustal thickness, which reflect more uniform mantle upwelling beneath the ridge axis. Here we present a systematic study of the residual mantle Bouguer gravity anomaly of 19 oceanic transform faults that reveals a strong correlation between gravity signature and spreading rate. Previous studies have shown that slow-slipping transform faults are marked by more positive gravity anomalies than their adjacent ridge segments, but our analysis reveals that intermediate and fast-slipping transform faults exhibit more negative gravity anomalies than their adjacent ridge segments. This finding indicates that there is a mass deficit at intermediate- and fast-slipping transform faults, which could reflect increased rock porosity, serpentinization of mantle peridotite, and/or crustal thickening. The most negative anomalies correspond to topographic highs flanking the transform faults, rather than to transform troughs (where deformation is probably focused and porosity and alteration are expected to be greatest), indicating that crustal thickening could be an important contributor to the negative gravity anomalies observed. This finding in turn suggests that three-dimensional magma accretion may occur near intermediate- and fast-slipping transform faults. PMID:17625563

  14. [Assisted hatching for improving embryo implantation. A bibliographical review].

    PubMed

    Hernández-Nieto, Carlos Alberto; Soto-Cossio, Luz Estefhany; Basurto-Díaz, David

    2015-04-01

    Embryo implantation represents the most critical step of the reproductive process in many species, to be successful requires a receptive endometrium, functional embryo at a stage of embryonic development and proper dialogue between embryonic and maternal tissues. Hatching is the process in which the blastocyst gets rid of the zona pellucida to be implemented. The failure in this factor can lead to reproductive problems, even under assisted reproduction techniques. Assisted hatching is a technique used in assisted reproduction laboratories to improve performance in the process of fecundation or in vitro fertilization. This technique is based on impairment or section of the zona pellucida using different techniques. In this review, the most common indications and techniques used to perform this procedure and improve success rates in assisted reproduction techniques are synthesized. PMID:26727756

  15. 29 CFR 1918.42 - Hatch beam and pontoon bridles.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Hatch beam and pontoon bridles. 1918.42 Section 1918.42... § 1918.42 Hatch beam and pontoon bridles. (a) Hatch beam and pontoon bridles shall be: (1) Long enough to reach the holes, rings, or other lifting attachments on the hatch beams and pontoons easily; (2)...

  16. 29 CFR 1918.42 - Hatch beam and pontoon bridles.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Hatch beam and pontoon bridles. 1918.42 Section 1918.42... § 1918.42 Hatch beam and pontoon bridles. (a) Hatch beam and pontoon bridles shall be: (1) Long enough to reach the holes, rings, or other lifting attachments on the hatch beams and pontoons easily; (2)...

  17. 29 CFR 1918.42 - Hatch beam and pontoon bridles.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Hatch beam and pontoon bridles. 1918.42 Section 1918.42... § 1918.42 Hatch beam and pontoon bridles. (a) Hatch beam and pontoon bridles shall be: (1) Long enough to reach the holes, rings, or other lifting attachments on the hatch beams and pontoons easily; (2)...

  18. 29 CFR 1918.42 - Hatch beam and pontoon bridles.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Hatch beam and pontoon bridles. 1918.42 Section 1918.42... § 1918.42 Hatch beam and pontoon bridles. (a) Hatch beam and pontoon bridles shall be: (1) Long enough to reach the holes, rings, or other lifting attachments on the hatch beams and pontoons easily; (2)...

  19. Comparison of hatching mode in pelagic and demersal eggs of two closely related species in the order pleuronectiformes.

    PubMed

    Kawaguchi, Mari; Sano, Kaori; Yoshizaki, Norio; Shimizu, Daisuke; Fujinami, Yuichiro; Noda, Tsutomu; Yasumasu, Shigeki

    2014-11-01

    We compared several characteristics of the pelagic eggs of Verasper variegatus with those of demersal eggs of Pseudopleuronectes yokohamae, both in the order Pleuronectiformes (halibuts or flatfishes). V. variegatus eggs had about twice the diameter of P. yokohamae eggs. However, the total egg protein weight of P. yokohamae was similar to that of V. variegatus. The specific gravity of P. yokohamae eggs was calculated to be 7-fold that of V. variegatus. The difference in size is the main feature distinguishing the two types of egg. The thickness of the egg envelope of P. yokohamae- more than twice that of V. variegatus-must affect the manner of hatching. The amount of hatching enzyme synthesized in pre-hatching embryo was estimated to be larger in P. yokohamae than V. variegatus. The distribution of hatching gland cells differed between the species. In V. variegates embryos, these were located on the yolk sac as a narrow ring-shaped belt, resulting in cleavage of the egg envelope into two parts by digesting a limited region of the egg envelope, called "rim-hatching". The hatching gland cells of P. yokohamae embryos were distributed all over the surface of the yolk sac, forming a hole through which the embryo could escape. Thus, the location of the hatching gland cells in pre-hatching embryos varied during the evolution of the Pleuronectiformes, depending on the egg type and manner of hatching. PMID:25366152

  20. Temperature Dependence of the O + HO2 Rate Coefficient

    NASA Technical Reports Server (NTRS)

    Nicovich, J. M.; Wine, P. H.

    1997-01-01

    A pulsed laser photolysis technique has been employed to investigate the kinetics of the radical-radical reaction O((sup 3)P) + HO2 OH + O2 over the temperature range 266-391 K in 80 Torr of N2 diluent gas. O((sup 3)P) was produced by 248.5-nm KrF laser photolysis of O3 followed by rapid quenching of O(1D) to O((sup 3)P) while HO2 was produced by simultaneous photolysis of H2O2 to create OH radicals which, in turn, reacted with H2O2 to yield HO2. The O((sup 3)P) temporal profile was monitored by using time-resolved resonance fluorescence spectroscopy. The HO2 concentration was calculated based on experimentally measured parameters. The following Arrhenius expression describes our experimental results: k(sub 1)(T) equals (2.91 +/- 0.70) x 10(exp -11) exp[(228 +/- 75)/T] where the errors are 2 sigma and represent precision only. The absolute uncertainty in k, at any temperature within the range 266-391 K is estimated to be +/- 22 percent. Our results are in excellent agreement with a discharge flow study of the temperature dependence of k(sub 1) in 1 Torr of He diluent reported by Keyser, and significantly reduce the uncertainty in the rate of this important stratospheric reaction at subambient temperatures.

  1. Effect of Storage Environment on Hatching of the Cyst Nematode Globodera ellingtonae

    PubMed Central

    Ingham, Russell E.; Kroese, Duncan; Zasada, Inga A.

    2015-01-01

    Globodera spp. eggs go through a diapause, which remains dormant until favorable hatching conditions are reached. Because of the regulatory concerns with cyst nematodes, it is often only possible to rear eggs for research in the greenhouse. However, hatch is often lower for greenhouse-produced eggs than for eggs obtained from the field. The goal of this research was to determine storage conditions for Globodera ellingtonae eggs produced in the greenhouse that would increase percentage hatch. Over 3 yr, G. ellingtonae greenhouse-produced eggs were stored in different environments (−20°C, 4°C, room temperature, and the field) in either dry or moist soil. Percentage hatch after exposure to the different environments was determined in potato root diffusate. Across two experiments, field-produced eggs had higher hatch rates (65.2%) than greenhouse-produced eggs (10.4%). Temperature did not have an appreciable influence on hatch of eggs stored dry in two experiments (2.8% to 8.4% and 3.8% to 8.6%), but hatch of eggs stored in moist soil was significantly higher than in dry soil at all temperatures except −20°C (26.8% and 28.7%). However, the ability of G. ellingtonae greenhouse-, microplot-, and field-produced eggs to reproduce on potato in field microplots was not different. Although it may not be possible to produce G. ellingtonae eggs in the greenhouse that have the magnitude of hatch as those produced in the field, hatching can be greatly increased by storing eggs in moist soil at either 4°C or room temperature. PMID:25861115

  2. Effect of Storage Environment on Hatching of the Cyst Nematode Globodera ellingtonae.

    PubMed

    Ingham, Russell E; Kroese, Duncan; Zasada, Inga A

    2015-03-01

    Globodera spp. eggs go through a diapause, which remains dormant until favorable hatching conditions are reached. Because of the regulatory concerns with cyst nematodes, it is often only possible to rear eggs for research in the greenhouse. However, hatch is often lower for greenhouse-produced eggs than for eggs obtained from the field. The goal of this research was to determine storage conditions for Globodera ellingtonae eggs produced in the greenhouse that would increase percentage hatch. Over 3 yr, G. ellingtonae greenhouse-produced eggs were stored in different environments (-20°C, 4°C, room temperature, and the field) in either dry or moist soil. Percentage hatch after exposure to the different environments was determined in potato root diffusate. Across two experiments, field-produced eggs had higher hatch rates (65.2%) than greenhouse-produced eggs (10.4%). Temperature did not have an appreciable influence on hatch of eggs stored dry in two experiments (2.8% to 8.4% and 3.8% to 8.6%), but hatch of eggs stored in moist soil was significantly higher than in dry soil at all temperatures except -20°C (26.8% and 28.7%). However, the ability of G. ellingtonae greenhouse-, microplot-, and field-produced eggs to reproduce on potato in field microplots was not different. Although it may not be possible to produce G. ellingtonae eggs in the greenhouse that have the magnitude of hatch as those produced in the field, hatching can be greatly increased by storing eggs in moist soil at either 4°C or room temperature. PMID:25861115

  3. Thermal effects in laser-assisted embryo hatching

    NASA Astrophysics Data System (ADS)

    Douglas-Hamilton, Diarmaid H.; Conia, Jerome D.

    2000-08-01

    Diode lasers [(lambda) equals 1480 nm] are used with in-vitro fertilization [IVF] as a promoter of embryo hatching. A focused laser beam is applied in vitro to form a channel in the zona pellucida (shell) of the pre-embryo. After transfer into the uterus, the embryo hatches: it extrudes itself through the channel and implants into the uterine wall. Laser-assisted hatching can result in improving implantation and pregnancy success rates. We present examples of zone pellucida ablation using animal models. In using the laser it is vital not to damage pre-embryo cells, e.g. by overheating. In order to define safe regimes we have derived some thermal side-effects of zona pellucida removal. The temperature profile in the beam and vicinity is predicted as function of laser pulse duration and power. In a crossed-beam experiment a HeNe laser probe detects the temperature-induced change in refractive index. We find that the diode laser beam produces superheated water approaching 200 C on the beam axis. Thermal histories during and following the laser pulse are given for regions in the neighborhood of the beam. We conclude that an optimum regime exists with pulse duration

  4. Hatching and fledging times from grassland passerine nests

    USGS Publications Warehouse

    Pietz, P.J.; Granfors, D.A.; Grant, T.A.

    2012-01-01

    Accurate estimates of fledging age are needed in field studies to avoid inducing premature fledging or missing the fledging event. Both may lead to misinterpretation of nest fate. Correctly assessing nest fate and length of the nestling period can be critical for accurate calculation of nest survival rates. For researchers who mark nestlings, knowing the age at which their activities may cause young to leave nests prematurely could prevent introducing bias to their studies. We obtained estimates of fledging age using data from grassland bird nests monitored from hatching through fledging with video-surveillance systems in North Dakota and Minnesota during 1996–2001. We compared these values to those obtained from traditional nest visits and from available literature. Mean and modal fledging ages for video-monitored nests were generally similar to those for visited nests, although Clay-colored Sparrows (Spizella pallida) typically fledged 1 day earlier from visited nests. Average fledging ages from both video and nest visits occurred within ranges reported in the literature, but expanded by 1–2 days the upper age limit for Clay-colored Sparrows and the lower age limit for Bobolinks (Dolichonyx oryzivorus). Video showed that eggs hatched throughout the day whereas most young fledged in the morning (06:30–12:30 CDT). Length of the hatching period for a clutch was usually >1 day and was positively correlated with clutch size. Length of the fledging period for a brood was usually <1 day, and in nearly half the nests, fledging was completed within <2 hr. Video surveillance has proven to be a useful tool for providing new information and for corroborating published statements related to hatching and fledging chronology. Comparison of data collected from video and nest visits showed that carefully conducted nest visits generally can provide reliable data for deriving estimates of survival.

  5. The Dependability of Student Ratings of Instructors across Sections.

    ERIC Educational Resources Information Center

    Sungsook, Kim C.

    The consistency of ratings between two sections of a course taught by an instructor within a given semester was studied by examining sources of variation in rating instructor/course obtained through a college teacher evaluation system. Data were analyzed for five business school instructors at a Sogang University in Seoul (South Korea). Each…

  6. Killifish Hatching and Orientation experiment MA-161

    NASA Technical Reports Server (NTRS)

    Scheld, H. W.; Boyd, J. F.; Bozarth, G. A.; Conner, J. A.; Eichler, V. B.; Fuller, P. M.; Hoffman, R. B.; Keefe, J. R.; Kuchnow, K. P.; Oppenheimer, J. M.

    1976-01-01

    The killifish Fundulus heteroclitus was used as a model system for study of embryonic development and vestibular adaptation in orbital flight. Juvenile fish in a zero gravity environment exhibited looping swimming activity similar to that observed during the Skylab 3 mission. Hatchings from a 336 hour egg stage were also observed to loop. At splashdown, both juveniles and hatchings exhibited a typical diving response suggesting relatively normal vestibular function. Juveniles exhibited swimming patterns suggestive of abnormal swim bladders. The embryos exhibited no abnormalities resulting from development in a zero gravity environment.

  7. Rate-dependent fracture characteristics of lumbar vertebral bodies.

    PubMed

    Stemper, Brian D; Yoganandan, Narayan; Baisden, Jamie L; Umale, Sagar; Shah, Alok S; Shender, Barry S; Paskoff, Glenn R

    2015-01-01

    Experimental testing incorporating lumbar columns and isolated components is essential to advance the understanding of injury tolerance and for the development of safety enhancements. This study incorporated a whole column axial acceleration model and an isolated vertebral body model to quantify compression rates during realistic loading and compressive tolerance of vertebrae. Eight lumbar columns and 53 vertebral bodies from 23 PMHS were used. Three-factor ANOVA was used to determine significant differences (p<0.05) in physiologic and failure biomechanics based on compression rate, spinal level, and gender. Results demonstrated a significant increase in ultimate force (i.e., fracture) from lower to higher compression rates. Ultimate stress also increased with compression rate. Displacement and strain to failure were consistent at both compression rates. Differences in ultimate mechanics between vertebral bodies obtained from males and females demonstrated non-significant trends, with female vertebral bodies having lower ultimate force that would be associated with decreased injury tolerance. This was likely a result of smaller vertebrae in that population. Combined with existing literature, results presented in this manuscript contribute to the understanding of lumbar spine tolerance during axial loading events that occur in both military and civilian environments with regard to effects of compression rate and gender. PMID:25154535

  8. Rate dependence of swelling in lithium-ion cells

    SciTech Connect

    Oh, KY; Siegel, JB; Secondo, L; Kim, SU; Samad, NA; Qin, JW; Anderson, D; Garikipati, K; Knobloch, A; Epureanu, BI; Monroe, CW; Stefanopoulou, A

    2014-12-01

    Swelling of a commercial 5 Ah lithium-ion cell with a nickel/manganese/cobalt-oxide cathode is investigated as a function of the charge state and the charge/discharge rate. In combination with sensitive displacement measurements, knowledge of the electrode configuration within this prismatic cell's interior allows macroscopic deformations of the casing to be correlated to electrochemical and mechanical transformations in individual anode/separator/cathode layers. Thermal expansion and interior charge state are both found to cause significant swelling. At low rates, where thermal expansion is negligible, the electrode sandwich dilates by as much as 1.5% as the charge state swings from 0% to 100% because of lithium-ion intercalation. At high rates a comparably large residual swelling was observed at the end of discharge. Thermal expansion caused by joule heating at high discharge rate results in battery swelling. The changes in displacement with respect to capacity at low rate correlate well with the potential changes known to accompany phase transitions in the electrode materials. Although the potential response changes minimally with the C-rate, the extent of swelling varies significantly, suggesting that measurements of swelling may provide a sensitive gauge for characterizing dynamic operating states. (C) 2014 Elsevier B.V. All rights reserved.

  9. Quantitative Adverse Outcome Pathway Analysis of Hatching in Zebrafish with CuO Nanoparticles.

    PubMed

    Muller, Erik B; Lin, Sijie; Nisbet, Roger M

    2015-10-01

    This study develops and evaluates a mechanistic model of the hatching of zebrafish eggs that were exposed to CuO engineered nanoparticles (ENP) in a high-throughput screening system and places this model in an adverse outcome pathway (AOP) that also includes CuO ENP dissolution and Cu bioaccumulation. Cu(2+) inhibits the proteolytic activity of Zebrafish Hatching Enzyme 1 and thereby delay or impair hatching success. This study demonstrates that noncompetitive inhibition kinetics describe the impact of dissolved Cu on hatching; it is estimated that indefinitely long exposure to 1.88 μM dissolved Cu in the environment reduces hatching enzyme activity by 50%. The complexity arising from CuO ENP dissolution and CuO ENP assisted bioaccumulation of Cu has led to apparently contradictory findings about ion versus "nano" effects on hatching. Model-mediated data analyses indicate that, relative to copper salts, CuO ENPs increase the uptake rates of Cu into the perivitelline space up to 8 times. The toxicity assessment framework in this study can be adapted to accommodate other types of toxicant, environmental samples and other aquatic oviparous species. PMID:26378804

  10. Reproduction, hatching success, and early naupliar survival in Centropages typicus

    NASA Astrophysics Data System (ADS)

    Ianora, A.; Miralto, A.; Halsband-Lenk, C.

    2007-02-01

    The broadcast spawner, Centropages typicus, is a very successful copepod species in many coastal areas of the Mediterranean Sea and North Atlantic Ocean. This review assembles the large amount of information on the reproduction and early life history of C. typicus that has emerged since the 1970s and has made this species one of the best-studied copepods, similar in that regard to species of Acartia and Calanus. Observations on mating behavior and the female gametogenic and oogenic cycles are presented, together with information on seasonal cycles of egg production rates in Mediterranean and Atlantic populations from various regions. These studies indicate a strong latitudinal gradient, with continuous reproduction and the main spawning season occurring earlier (late winter/spring) in warmer waters such as the Mediterranean Sea, compared to northern areas such as the North Sea and in the Kattegat, where C. typicus actively reproduces mainly in late summer and fall with reproduction ceasing altogether in winter in the German Bight. These observations strongly suggest that temperature is the controlling factor for reproductive activity in this species. Egg development times are also temperature dependent but do not vary with latitude, and there is as yet no conclusive evidence that diapause egg production occurs in C. typicus. Laboratory experiments have shown that food quantity and quality both affect fecundity and offspring fitness, but most of these studies have focused on diatom and dinoflagellate diets and non-algal prey have been strongly underrepresented, despite their importance for this omnivorous copepod. Large fluctuations in hatching success and naupliar survival have been reported in field surveys and have subsequently been related to maternal feeding history and food quality or toxicity in laboratory experiments. We identify future lines of research that will help to explain the interannual variability in breeding intensity and recruitment of C. typicus

  11. Egg hatching of two locusts, Schistocerca gregaria and Locusta migratoria, in response to light and temperature cycles.

    PubMed

    Nishide, Yudai; Tanaka, Seiji; Saeki, Shinjiro

    2015-05-01

    The present study showed that the eggs of the desert locust, Schistocerca gregaria, and the migratory locust, Locusta migratoria, responded to photoperiod by hatching when placed on sand in the laboratory. S. gregaria mainly hatched during the dark phase and L. migratoria during the light phase. The importance of light as a hatching cue depended on the magnitude of the temperature change during the thermoperiod; photoperiod played a more important role in the control of hatching time in both species when the magnitude of the temperature change was small. In addition, the eggs of the two species that were covered with sand did not respond to photoperiod and hatched during both the light and dark phases, indicating that light did not penetrate through the sand. Because locust eggs are normally laid as egg pods and a foam plug is deposited between the egg mass and the ground surface, we tested a possibility that naturally deposited eggs perceived light through the foam plug. The eggs that were deposited and left undisturbed in the sand hatched during the light and dark phases at similar frequencies. These results suggest that the eggs of both locust species responded to light and controlled their hatching timing accordingly but would not use light as a hatching cue in the field. The evolutionary significance of the ability of eggs to respond to light in these locusts was discussed. PMID:25796138

  12. In vitro hatching of Trichuris suis eggs.

    PubMed

    Vejzagić, Nermina; Thamsborg, Stig Milan; Kringel, Helene; Roepstorff, Allan; Bruun, Johan Musaeus; Kapel, Christian M O

    2015-07-01

    Eggs of the pig whipworm, Trichuris suis ova (TSO), are currently tested in human clinical trials for their potential immunomodulatory capacity. The biological potency of TSO (egg viability and infectivity) is traditionally assessed in Göttingen minipigs as the establishment of intestinal larvae after inoculation with a known number of eggs. To minimize testing in animal models, development of an in vitro egg hatching assay is proposed as a reliable, cost-effective, and a faster alternative to test the egg viability. The present study aimed to investigate the influence of different chemical, physical, and biological factors on egg hatching. Thus, in a series of experiments and in different combinations, the eggs were stimulated with glass beads, artificial gastric juice, bile salt and trypsin solution, fermentation gut medium, or stimulated with mucosal scrapings from the ileum and the large intestine of the infected and uninfected Göttingen minipig. Mechanical stimulation with glass beads presented a simple and reproducible method for egg hatching. However, incubation of eggs with mucosal scrapings from the ileum, caecum, and colon for 24 h at 38 °C significantly increased hatching. PMID:26008635

  13. 29 CFR 1918.35 - Open hatches.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... hatches around which employees must work that are not protected to a height of 24 inches (.61 m) by coamings shall be guarded by taut lines or barricades at a height of 36 to 42 inches (.91 to 1.07 m)...

  14. Mechanical Hatching Egg Sanitization: A Fresh Look

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three to four decades ago, hatching egg sanitization was done by immersion of eggs in an egg-gathering basket (plastic-coated metal wire) into a small vat with a heating element and disinfectant solution. This procedure failed miserably for several reasons. First, the eggs were not subjected to the...

  15. Problems associated with incubation and hatching

    USGS Publications Warehouse

    Olsen, G.H.

    1989-01-01

    There are numerous problems in incubation and hatching that can result in a dead embryo. Many of these problems can be prevented if the proper diagnosis of embryo mortality is made and the client instructed on how to prevent the probem in the future. This session is designed to give the avian practitioner an introduction to this area.

  16. MECHANICAL HATCHING EGG SANITIZATION: A FRESH LOOK

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Egg sanitation has had a dubious history in North America until recent years. Three to four decades ago, hatching egg sanitization was done by immersion of eggs in an egg-gathering basket (plastic coated metal wire) into a small vat with a heating element and disinfectant solution. This procedure ...

  17. Rate dependent of strength in metallic glasses at different temperatures

    PubMed Central

    Wang, Y. W.; Bian, X. L.; Wu, S. W.; Hussain, I.; Jia, Y. D.; Yi, J.; Wang, G.

    2016-01-01

    The correlation between the strength at the macroscale and the elastic deformation as well as shear cracking behavior at the microscale of bulk metallic glasses (BMGs) is investigated. The temperatures of 298 K and 77 K as well as the strain rate ranging from 10−6 s−1 to 10−2 s−1 are applied to the BMGs, in which the mechanical responses of the BMGs are profiled through the compression tests. The yield strength is associated with the activation of the elementary deformation unit, which is insensitive to the strain rate. The maximum compressive strength is linked to the crack propagation during shear fracture process, which is influenced by the strain rate. The cryogenic temperature of 77 K significantly improves the yield strength and the maximum compressive strength of the BMGs. PMID:27270688

  18. Rate dependent of strength in metallic glasses at different temperatures.

    PubMed

    Wang, Y W; Bian, X L; Wu, S W; Hussain, I; Jia, Y D; Yi, J; Wang, G

    2016-01-01

    The correlation between the strength at the macroscale and the elastic deformation as well as shear cracking behavior at the microscale of bulk metallic glasses (BMGs) is investigated. The temperatures of 298 K and 77 K as well as the strain rate ranging from 10(-6) s(-1) to 10(-2) s(-1) are applied to the BMGs, in which the mechanical responses of the BMGs are profiled through the compression tests. The yield strength is associated with the activation of the elementary deformation unit, which is insensitive to the strain rate. The maximum compressive strength is linked to the crack propagation during shear fracture process, which is influenced by the strain rate. The cryogenic temperature of 77 K significantly improves the yield strength and the maximum compressive strength of the BMGs. PMID:27270688

  19. Rate dependent of strength in metallic glasses at different temperatures

    NASA Astrophysics Data System (ADS)

    Wang, Y. W.; Bian, X. L.; Wu, S. W.; Hussain, I.; Jia, Y. D.; Yi, J.; Wang, G.

    2016-06-01

    The correlation between the strength at the macroscale and the elastic deformation as well as shear cracking behavior at the microscale of bulk metallic glasses (BMGs) is investigated. The temperatures of 298 K and 77 K as well as the strain rate ranging from 10‑6 s‑1 to 10‑2 s‑1 are applied to the BMGs, in which the mechanical responses of the BMGs are profiled through the compression tests. The yield strength is associated with the activation of the elementary deformation unit, which is insensitive to the strain rate. The maximum compressive strength is linked to the crack propagation during shear fracture process, which is influenced by the strain rate. The cryogenic temperature of 77 K significantly improves the yield strength and the maximum compressive strength of the BMGs.

  20. Compositions and functions of the hatching froth from ricefield eel (Monopterus albus Zuiew).

    PubMed

    Yin, Shaowu; Liu, Yun

    2010-06-01

    The ricefield eel (Monopterus albus) is an economic fish species in China. To improve its artificial reproduction, we studied the compositions and functions of the hatching froth secreted by ricefield eels. The froth showed a viscosity of 2.72 mPaS, composed of glycoproteins with a sugar content of 0.156 mg/ml and a protein content of 0.250 mg/ml at a ratio of 1.60. The froth proteins were identified by SDS-PAGE as four proteins with the molecular weights of 42.5, 58.6, 65.3, and 98.2 kDa respectively. Their total amino acid content was 201.88 mg/100 ml, consisting of 16 kinds of amino acids. Filed observation revealed three beneficial effects of the froth on the hatching of the eel eggs. First, the froth increased the hatching rates of fertilized eggs at a range of water temperatures. Second, the froth decreased the rates of infection of the fertilized eggs by the water mold. Finally, the froth accelerated velum breakage in the fertilized eggs. Of the different hatching methods, froth incubation achieved the highest hatching rate and larvae survival rate. These results demonstrate the indispensable function of the froth of ricefield eels, and offer practical reasons for protecting the froth during the breeding season. PMID:18949569

  1. Dependence of rate constants on vibrational temperatures - An Arrhenius description

    NASA Technical Reports Server (NTRS)

    Ford, D. I.; Johnson, R. E.

    1988-01-01

    An interpretation of the variation of rate constants with vibrational temperature is proposed which introduces parameters analogous to those of the classical Arrhenius expression. The constancy of vibrational activation energy is studied for the dissociaton of NO, the ion-molecular reaction of O(+) with N2, and the atom exchange reaction of I with H2. It is found that when a Boltzmann distribution for vibrational states is applicable, the variation of the rate constant with the vibrational temperature can be used to define a vibrational activation energy. The method has application to exchange reactions where a vibrational energy threshold exists.

  2. Unexpectedly large dose rate dependent output from a linear accelerator.

    PubMed

    Cheng, P C; Kubo, H

    1988-01-01

    During our routine calibration of a Varian Clinac-20 linear accelerator, the absorbed dose for a fixed monitor unit (mu) was found to decrease with increasing dose rate. Between dose rates of 100 and 500 mu/min, there was up to 20% difference in absorbed dose for a 20-MeV electron beam. The cause of this problem was a failure in the electronics circuit of an integrating board. This paper presents our analysis of the problem and suggests a possible means of isolating such a failure to warn technologists, physicists, and engineers. PMID:3141760

  3. Strain rate dependent properties of human craniovertebral ligaments.

    PubMed

    Mattucci, Stephen F E; Moulton, Jeffrey A; Chandrashekar, Naveen; Cronin, Duane S

    2013-07-01

    Craniovertebral ligaments were tested to failure under tensile loading. Ligaments tested included: transverse ligament, anterior atlanto occipital membrane, posterior atlanto occipital membrane, capsular ligaments between Skull-C1 and C1-C2, anterior atlantoaxial membrane, posterior atlantoaxial membrane and the tectorial membrane/vertical cruciate/apical/alar ligament complex. The objective of this study was to obtain mechanical properties of craniovertebral ligaments of a younger population, at varying strain rates representative of automotive crash scenarios, and investigate rate and gender effects for use in numerical models of the cervical spine. There have been few studies conducted on the mechanical properties of human craniovertebral ligaments. Only one study has tested all of the ligaments, and previous studies use older age specimens (mean age 67, from most complete study). Further, tests were often not performed at elongation rates representative of car crash scenarios. Previous studies did not perform tests in an environment resembling in vivo conditions, which has been shown to have a significant effect on ligament tensile behaviour. Fifty-four craniovertebral ligaments were isolated from twenty-one spines, and tested to failure in tension under simulated in vivo temperature and hydration levels, at quasi-static (0.5 s(-1)) and high strain rates (150 s(-1)). Values for failure force, failure elongation, stiffness, and toe region elongation were obtained from force-displacement curves. Values were analyzed for strain rate and gender effects. Increased strain rate produced several significant effects including: higher failure forces for the transverse ligament and capsular ligament (Skull-C1), lower failure elongation for the tectorial membrane complex, higher stiffness for the tectorial membrane complex and capsular ligament (Skull-C1), and lower toe region elongation for capsular ligament (Skull-C1). Gender effects were limited. Ligament tests

  4. Dependence of Interstellar Turbulent Pressure on Supernova Rate

    NASA Astrophysics Data System (ADS)

    Joung, M. Ryan; Mac Low, Mordecai-Mark; Bryan, Greg L.

    2009-10-01

    Feedback from massive stars is one of the least understood aspects of galaxy formation. We perform a suite of vertically stratified local interstellar medium (ISM) models in which supernova (SN) rates and vertical gas column densities are systematically varied based on the Schmidt-Kennicutt law. Our simulations have a sufficiently high spatial resolution (1.95 pc) to follow the hydrodynamic interactions among multiple SNe that structure the interstellar medium. At a given SN rate, we find that the mean mass-weighted sound speed and velocity dispersion decrease as the inverse square root of gas density. The sum of thermal and turbulent pressures is nearly constant in the midplane, so the effective equation of state is isobaric. In contrast, across our four models having SN rates that range from 1 to 512 times the Galactic SN rate, the mass-weighted velocity dispersion remains in the range 4-6 km s-1. Hence, gas averaged over ~100 pc regions follows P vprop ρα with α ≈ 1, indicating that the effective equation of state on this scale is close to isothermal. Simulated H I emission lines have widths of 10-18 km s-1, comparable to observed values. In our highest SN rate model, superbubble blow-outs occur, and the turbulent pressure on large scales is gsim4 times higher than the thermal pressure. We find a tight correlation between the thermal and turbulent pressures averaged over ~100 pc regions in the midplane of each model, as well as across the four ISM models. We construct a subgrid model for turbulent pressure based on analytic arguments and explicitly calibrate it against our stratified ISM simulations. The subgrid model provides a simple yet physically motivated way to include SN feedback in cosmological simulations.

  5. DEPENDENCE OF INTERSTELLAR TURBULENT PRESSURE ON SUPERNOVA RATE

    SciTech Connect

    Joung, M. Ryan; Mac Low, Mordecai-Mark; Bryan, Greg L. E-mail: mordecai@amnh.or

    2009-10-10

    Feedback from massive stars is one of the least understood aspects of galaxy formation. We perform a suite of vertically stratified local interstellar medium (ISM) models in which supernova (SN) rates and vertical gas column densities are systematically varied based on the Schmidt-Kennicutt law. Our simulations have a sufficiently high spatial resolution (1.95 pc) to follow the hydrodynamic interactions among multiple SNe that structure the interstellar medium. At a given SN rate, we find that the mean mass-weighted sound speed and velocity dispersion decrease as the inverse square root of gas density. The sum of thermal and turbulent pressures is nearly constant in the midplane, so the effective equation of state is isobaric. In contrast, across our four models having SN rates that range from 1 to 512 times the Galactic SN rate, the mass-weighted velocity dispersion remains in the range 4-6 km s{sup -1}. Hence, gas averaged over approx100 pc regions follows P propor to rho{sup a}lpha with alpha approx 1, indicating that the effective equation of state on this scale is close to isothermal. Simulated H I emission lines have widths of 10-18 km s{sup -1}, comparable to observed values. In our highest SN rate model, superbubble blow-outs occur, and the turbulent pressure on large scales is approx>4 times higher than the thermal pressure. We find a tight correlation between the thermal and turbulent pressures averaged over approx100 pc regions in the midplane of each model, as well as across the four ISM models. We construct a subgrid model for turbulent pressure based on analytic arguments and explicitly calibrate it against our stratified ISM simulations. The subgrid model provides a simple yet physically motivated way to include SN feedback in cosmological simulations.

  6. Magnetic Phase Dependence of the Nickel Carbonyl Reaction Rate

    NASA Astrophysics Data System (ADS)

    Mehta, R. S.; Dresselhaus, M. S.; Dresselhaus, G.; Zeiger, H. J.

    1980-07-01

    The activation energy for Ni(CO)4 formation on surfaces of Ni1-xCux alloys is found to be greater when the metallic substrate is ferromagnetic than when it is paramagnetic. This difference in activation energy is identified with the bulk exchange energy of the substrate and depends on the bulk Ni concentration. On the basis of the experimental results, a model for the step associated with rupture of the metallic bond is presented.

  7. 1. VIEW OF THE ENTRANCE TO THE HATCH ADIT (FEATURE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. VIEW OF THE ENTRANCE TO THE HATCH ADIT (FEATURE B-28), FACING WEST. (OCTOBER, 1995) - Nevada Lucky Tiger Mill & Mine, Hatch Adit, East slope of Buckskin Mountain, Paradise Valley, Humboldt County, NV

  8. Prebreeding survival of Roseate Terns Sterna dougallii varies with sex, hatching order and hatching date

    USGS Publications Warehouse

    Nisbet, Ian C.T.; Monticelli, David; Spendelow, Jeffrey A.; Szczys, Patricia

    2016-01-01

    Unequal sex ratios can reduce the productivity of animal populations and are especially prevalent among endangered species. A cohort of 333 Roseate Tern Sterna dougallii chicks at a site where the adult sex ratio was skewed towards females was sexed at hatching and followed through fledging and return to the breeding area, and subsequently during adulthood. The entire regional metapopulation was sampled for returning birds. Prebreeding survival (from fledging to age 3 years) was lower in males than in females, but only among B-chicks (second in hatching order). Prebreeding survival also declined with hatching date. The proportion of females in this cohort increased from 54.6% at hatching to 56.2% at fledging and to an estimated 58.0% among survivors at age 3 years. This was more than sufficient to explain the degree of skew in the sex ratio of the adult population, but changes in this degree of skew during the study period make it difficult to identify the influence of a single cohort of recruits. Many studies of prebreeding survival in other bird species have identified effects of sex, hatching order or hatching date, but no previous study has tested for effects of all three factors simultaneously.

  9. Liver receptor homolog 1 influences blastocyst hatching in pigs

    PubMed Central

    GUO, Jing; ZHAO, Ming-Hui; LIANG, Shuang; CHOI, Jeong-Woo; KIM, Nam-Hyung; CUI, Xiang-Shun

    2016-01-01

    Liver receptor homolog 1 (Lrh1, also known as Nr5a2) belongs to the orphan nuclear receptor superfamily and has diverse functions in development, metabolism, and cell differentiation and death. Lrh1 regulates the expression of Oct4, which is a key factor of early embryonic differentiation. However, the role of Lrh1 in early development of mammalian embryo is unknown. In the present study, the localization, Lrh1 mRNA expression, and LRH1 protein levels in porcine early parthenotes were examined by immunofluorescence and real-time reverse-transcription polymerase chain reaction. To determine the role of Lrh1 in porcine early embryo development, the parthenotes were treated with the specific LRH1 antagonist 505601. The immunofluorescence signal for LRH1 was only observed in the nucleus of blastocysts. The blastocyst developmental rate in the presence of 50 and 100 μM 505601 was significantly lower than that in the control group. The blastocyst hatching rate was also reduced in the presence of 50 and 100 μM 505601 than that under control conditions. The latter effect was possibly due to the decreased expression of hatching-related genes such as Fn1, Itgα5, and Cox2 upon the inhibition of Lrh1. Incubation with the LRH1 antagonist also increased the number of apoptotic cells among the blastocysts. Moreover, LRH1 inhibition enhanced the expression of the pro-apoptotic genes Bax and Casp3, and reduced the expression of the anti-apoptotic gene Bcl2. Lrh1 inhibition also led to significant decrease in the expression levels of Oct4 mRNA and octamer-binding transcription factor 4 (OCT4) protein in the blastocysts. In conclusion, Lrh1 affects blastocyst formation and hatching in porcine embryonic development through the regulation of OCT4 expression and cell apoptosis. PMID:26971889

  10. Density dependence, whitebark pine, and vital rates of grizzly bears

    USGS Publications Warehouse

    van Manen, Frank T.; Haroldson, Mark A.; Bjornlie, Daniel D; Ebinger, Michael R.; Thompson, Daniel J.; Costello, Cecily M; White, Gary C.

    2016-01-01

    Understanding factors influencing changes in population trajectory is important for effective wildlife management, particularly for populations of conservation concern. Annual population growth of the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem, USA has slowed from 4.2–7.6% during 1983–2001 to 0.3–2.2% during 2002–2011. Substantial changes in availability of a key food source and bear population density have occurred. Whitebark pine (Pinus albicaulis), the seeds of which are a valuable but variable fall food for grizzly bears, has experienced substantial mortality primarily due to a mountain pine beetle (Dendroctonus ponderosae) outbreak that started in the early 2000s. Positive growth rates of grizzly bears have resulted in populations reaching high densities in some areas and have contributed to continued range expansion. We tested research hypotheses to examine if changes in vital rates detected during the past decade were more associated with whitebark pine decline or, alternatively, increasing grizzly bear density. We focused our assessment on known-fate data to estimate survival of cubs-of-the-year (cubs), yearlings, and independent bears (≥2 yrs), and reproductive transition of females from having no offspring to having cubs. We used spatially and temporally explicit indices for grizzly bear density and whitebark pine mortality as individual covariates. Models indicated moderate support for an increase in survival of independent male bears over 1983–2012, whereas independent female survival did not change. Cub survival, yearling survival, and reproductive transition from no offspring to cubs all changed during the 30-year study period, with lower rates evident during the last 10–15 years. Cub survival and reproductive transition were negatively associated with an index of grizzly bear density, indicating greater declines where bear densities were higher. Our analyses did not support a similar relationship for the

  11. Binary accretion rates: dependence on temperature and mass ratio

    NASA Astrophysics Data System (ADS)

    Young, M. D.; Clarke, C. J.

    2015-09-01

    We perform a series of 2D smoothed particle hydrodynamics simulations of gas accretion on to binaries via a circumbinary disc, for a range of gas temperatures and binary mass ratios (q). We show that increasing the gas temperature increases the accretion rate on to the primary for all values of the binary mass ratio: for example, for q = 0.1 and a fixed binary separation, an increase of normalized sound speed by a factor of 5 (from our `cold' to `hot' simulations) changes the fraction of the accreted gas that flows on to the primary from 10 to ˜40 per cent. We present a simple parametrization for the average accretion rate of each binary component accurate to within a few per cent and argue that this parametrization (rather than those in the literature based on warmer simulations) is relevant to supermassive black hole accretion and all but the widest stellar binaries. We present trajectories for the growth of q during circumbinary disc accretion and argue that the period distribution of stellar `twin' binaries is strong evidence for the importance of circumbinary accretion. We also show that our parametrization of binary accretion increases the minimum mass ratio needed for spin alignment of supermassive black holes to q ˜ 0.4, with potentially important implications for the magnitude of velocity kicks acquired during black hole mergers.

  12. Texture-dependent anaerobic microsites constrain soil carbon oxidation rates

    NASA Astrophysics Data System (ADS)

    Keiluweit, Marco; Fendorf, Scott

    2016-04-01

    Soil texture, which is a product of parent material, climate and other soil forming factors, is a predictor for long-term storage of soil organic carbon (SOC) storage in many soil ecosystems. Positive correlation between texture (particularly clay content) and SOC storage have long been attributed to protective associations between clay minerals and organic compounds that prevent microbial and enzymatic access - a mechanism commonly referred to as 'mineral protection'. Texture therefore acts as the primary proxy for mineral protection in terrestrial ecosystem models used to assess SOC storage and its sensitivity to global change impacts. Here we show that this protective effect of texture is not only due to mineral protection, but also to the formation of anaerobic microsites. Combining micro-scale laboratory experiments with field-scale observations, we find that oxygen diffusion limitations within clay-rich domains create anaerobic microsites within seemingly well-aerated soils, shifting microbial metabolism to less efficient anaerobic SOC oxidation pathways. Kinetic and thermodynamic constraints reduce SOC oxidation rates within these anaerobic microsites by an order of magnitude relative to aerobic rates, and caused the preservation of bioavailable, polymeric and reduced organic compounds. Lifting these metabolic constraints through increased soil aeration (e.g., through changes in precipitation patterns or land use) may stimulate microbial oxidation of this inherently bioavailable SOC pool. Models that attribute the effects of texture merely to 'mineral protection' may therefore underestimate the vulnerability of soil C to global change impacts.

  13. Enzyme surface rigidity tunes the temperature dependence of catalytic rates.

    PubMed

    Isaksen, Geir Villy; Åqvist, Johan; Brandsdal, Bjørn Olav

    2016-07-12

    The structural origin of enzyme adaptation to low temperature, allowing efficient catalysis of chemical reactions even near the freezing point of water, remains a fundamental puzzle in biocatalysis. A remarkable universal fingerprint shared by all cold-active enzymes is a reduction of the activation enthalpy accompanied by a more negative entropy, which alleviates the exponential decrease in chemical reaction rates caused by lowering of the temperature. Herein, we explore the role of protein surface mobility in determining this enthalpy-entropy balance. The effects of modifying surface rigidity in cold- and warm-active trypsins are demonstrated here by calculation of high-precision Arrhenius plots and thermodynamic activation parameters for the peptide hydrolysis reaction, using extensive computer simulations. The protein surface flexibility is systematically varied by applying positional restraints, causing the remarkable effect of turning the cold-active trypsin into a variant with mesophilic characteristics without changing the amino acid sequence. Furthermore, we show that just restraining a key surface loop causes the same effect as a point mutation in that loop between the cold- and warm-active trypsin. Importantly, changes in the activation enthalpy-entropy balance of up to 10 kcal/mol are almost perfectly balanced at room temperature, whereas they yield significantly higher rates at low temperatures for the cold-adapted enzyme. PMID:27354533

  14. Size and rate dependent necking in thin metallic films

    NASA Astrophysics Data System (ADS)

    Pardoen, T.

    2014-01-01

    The control of the ductility of thin metallic films is a major issue in a variety of technologies involving flexible electronics, MEMS and deformable coatings. An enhanced closed form 1D imperfection based localization analysis is developed in order to investigate the mechanics of diffuse necking in metallic films. The model relies on a description of the localization process in a finite length specimen using either a 2- or 3-zone model, under plane stress or plane strain tension conditions. A strain gradient plasticity contribution to the stabilization of the localization process is taken into account in the hardening response through a simple estimate of the deformation gradient inside the necking zone. The model, with gradient plasticity effects, is validated towards 2D finite element simulations. The response of the material involves both strain-hardening and rate sensitivity, as well as possible creep relaxation. The plastic flow parameters are related to the grain size and film thickness. The model shows, in agreement with experiments, that the ductility can either drop to small values for very small grain sizes and/or film thickness due to the high strength and to the presence of imperfections, or can remain constant or even increase owing to an increased rate sensitivity resulting from thermally activated mechanisms. This last stabilization effect can be reinforced by gradient plasticity effects if allowed by the dominant deformation mechanism.

  15. Enzyme surface rigidity tunes the temperature dependence of catalytic rates

    PubMed Central

    Isaksen, Geir Villy; Åqvist, Johan; Brandsdal, Bjørn Olav

    2016-01-01

    The structural origin of enzyme adaptation to low temperature, allowing efficient catalysis of chemical reactions even near the freezing point of water, remains a fundamental puzzle in biocatalysis. A remarkable universal fingerprint shared by all cold-active enzymes is a reduction of the activation enthalpy accompanied by a more negative entropy, which alleviates the exponential decrease in chemical reaction rates caused by lowering of the temperature. Herein, we explore the role of protein surface mobility in determining this enthalpy–entropy balance. The effects of modifying surface rigidity in cold- and warm-active trypsins are demonstrated here by calculation of high-precision Arrhenius plots and thermodynamic activation parameters for the peptide hydrolysis reaction, using extensive computer simulations. The protein surface flexibility is systematically varied by applying positional restraints, causing the remarkable effect of turning the cold-active trypsin into a variant with mesophilic characteristics without changing the amino acid sequence. Furthermore, we show that just restraining a key surface loop causes the same effect as a point mutation in that loop between the cold- and warm-active trypsin. Importantly, changes in the activation enthalpy–entropy balance of up to 10 kcal/mol are almost perfectly balanced at room temperature, whereas they yield significantly higher rates at low temperatures for the cold-adapted enzyme. PMID:27354533

  16. Phenological synchronization drives demographic rates of populations.

    PubMed

    Rasmussen, Nick L; Rudolf, Volker H W

    2015-07-01

    Phenology is increasingly recognized as an important factor structuring communities because it determines when and at what life stage organisms interact. Previous work indicates that changes in first or mean timing of a phenological event can affect populations and communities, but little is known about the consequences of changes in the distribution (e.g., synchrony) of a phenological event. We conducted an experiment using an anuran study system to determine how synchrony of reproduction and egg hatching affects offspring performance, whether the effects are density dependent, and how hatching synchrony influences the synchrony of a subsequent phenological event (metamorphosis). Changes in hatching synchrony altered survival, development rates, and body size at metamorphosis, which can affect post-metamorphosis performance. The degree of synchrony at hatching also affected the degree of synchrony at metamorphosis, indicating that timing of one stage can carry over to affect that of later ones. Importantly, these effects were all density dependent, likely because decreasing hatching synchrony switched intraspecific interactions from scramble to contest competition. This study demonstrates that phenological synchrony has important consequences for ecological interactions and population dynamics, emphasizing the need to develop a comprehensive understanding of how shifts in phenological distributions affect communities. PMID:26378297

  17. Section BB Hatch Coating; Framing Plan on Line C Lodging ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Section B-B Hatch Coating; Framing Plan on Line C Lodging Knees at Hatch; Elevation A-A Hull Framing; Section at Hatch Frame 36, Starboard Looking Aft; Midship Section Frame 37, Port Looking Aft - Steam Schooner WAPAMA, Kaiser Shipyard No. 3 (Shoal Point), Richmond, Contra Costa County, CA

  18. 9 CFR 147.22 - Hatching egg sanitation.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Hatching egg sanitation. 147.22... Procedures § 147.22 Hatching egg sanitation. Hatching eggs should be collected from the nests at frequent... practices should be observed: (a) Cleaned and disinfected containers, such as egg flats, should be used...

  19. 9 CFR 147.22 - Hatching egg sanitation.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Hatching egg sanitation. 147.22... Procedures § 147.22 Hatching egg sanitation. Hatching eggs should be collected from the nests at frequent... practices should be observed: (a) Cleaned and disinfected containers, such as egg flats, should be used...

  20. 9 CFR 147.22 - Hatching egg sanitation.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Hatching egg sanitation. 147.22... Procedures § 147.22 Hatching egg sanitation. Hatching eggs should be collected from the nests at frequent... practices should be observed: (a) Cleaned and disinfected containers, such as egg flats, should be used...

  1. 9 CFR 147.22 - Hatching egg sanitation.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Hatching egg sanitation. 147.22... Procedures § 147.22 Hatching egg sanitation. Hatching eggs should be collected from the nests at frequent... practices should be observed: (a) Cleaned and disinfected containers, such as egg flats, should be used...

  2. 9 CFR 147.22 - Hatching egg sanitation.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Hatching egg sanitation. 147.22... Procedures § 147.22 Hatching egg sanitation. Hatching eggs should be collected from the nests at frequent... practices should be observed: (a) Cleaned and disinfected containers, such as egg flats, should be used...

  3. 46 CFR 169.747 - Watertight doors and hatches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Watertight doors and hatches. 169.747 Section 169.747... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.747 Watertight doors and hatches. Each watertight door and watertight hatch must be marked on both sides in at least 1-inch...

  4. 46 CFR 169.747 - Watertight doors and hatches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Watertight doors and hatches. 169.747 Section 169.747... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.747 Watertight doors and hatches. Each watertight door and watertight hatch must be marked on both sides in at least 1-inch...

  5. 46 CFR 185.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Watertight doors and watertight hatches. 185.610 Section... (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.610 Watertight doors and watertight hatches. Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least...

  6. 46 CFR 185.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Watertight doors and watertight hatches. 185.610 Section... (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.610 Watertight doors and watertight hatches. Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least...

  7. 46 CFR 185.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Watertight doors and watertight hatches. 185.610 Section... (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.610 Watertight doors and watertight hatches. Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least...

  8. 46 CFR 169.747 - Watertight doors and hatches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Watertight doors and hatches. 169.747 Section 169.747... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.747 Watertight doors and hatches. Each watertight door and watertight hatch must be marked on both sides in at least 1-inch...

  9. 46 CFR 169.747 - Watertight doors and hatches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Watertight doors and hatches. 169.747 Section 169.747... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.747 Watertight doors and hatches. Each watertight door and watertight hatch must be marked on both sides in at least 1-inch...

  10. 46 CFR 169.747 - Watertight doors and hatches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Watertight doors and hatches. 169.747 Section 169.747... Vessel Control, Miscellaneous Systems, and Equipment Markings § 169.747 Watertight doors and hatches. Each watertight door and watertight hatch must be marked on both sides in at least 1-inch...

  11. 46 CFR 185.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Watertight doors and watertight hatches. 185.610 Section... (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.610 Watertight doors and watertight hatches. Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least...

  12. 46 CFR 185.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Watertight doors and watertight hatches. 185.610 Section... (UNDER 100 GROSS TONS) OPERATIONS Markings Required § 185.610 Watertight doors and watertight hatches. Watertight doors and watertight hatches must be marked on both sides in clearly legible letters at least...

  13. Heterodera glycines hatching behavior in field collections, laboratory culture and exposure to low temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Heterodera glycines collected from fields in Maryland exhibited very low hatch and reproduction rates in the laboratory. When such eggs were used to establish a laboratory culture on Glycine max, low reproductive rates continued for 2 generations. However, after 2 generations, the field egg derived ...

  14. Hatching asynchrony in Burrowing Owls is influenced by clutch size and hatching success but not by food.

    PubMed

    Wellicome, Troy I

    2005-01-01

    In most animals, siblings from a given reproductive event emerge over a very short period of time. In contrast, many species of birds hatch their young asynchronously over a period of days or weeks, handicapping last-hatched chicks with an age and size disadvantage. Numerous studies have examined the adaptive significance of this atypical hatching pattern, but few have attempted to explain the considerable intrapopulation variation that exists in hatching asynchrony. I explored proximate determinants of hatching asynchrony by monitoring 112 Burrowing Owl (Athene cunicularia) nests in the grasslands of southern Saskatchewan, Canada, over 4 years. Age disparities between first- and last-hatched siblings (i.e., hatching spans) varied considerably, ranging between 1 and 7 days (mode = 4 days). These hatching spans increased with increased hatching success. Hatching spans also increased with larger clutches, but the increase was less than predicted given the increased time required to lay more eggs. Hatching span was unrelated to number of prey cached in the nest during egg laying (an index of food availability), and was unaltered by a year of super-abundant prey. Furthermore, pairs given extra food during laying had hatching spans equal to those of unsupplemented control pairs. These results were inconsistent with both the energy constraint and facultative manipulation hypotheses, which predict that hatching asynchrony should vary with the level of food during laying, when incubation onset is determined. Burrowing Owls were apparently free of food limitation early in breeding, yet may not have been able to optimize hatching spans because food conditions during laying were largely unrelated to food conditions during brooding. Thus, one of the premises for facultative manipulation of hatching asynchrony-that laying females are able to forecast post-hatch food conditions-may not have been met for this population of Burrowing Owls. PMID:15480800

  15. Strain-rate dependence for Ni/Al hybrid foams

    NASA Astrophysics Data System (ADS)

    Jung, Anne; Larcher, Martin; Jirousek, Ondrej; Koudelka, Petr; Solomos, George

    2015-09-01

    Shock absorption often needs stiff but lightweight materials that exhibit a large kinetic energy absorption capability. Open-cell metal foams are artificial structures, which due to their plateau stress, including a strong hysteresis, can in principle absorb large amounts of energy. However, their plateau stress is too low for many applications. In this study, we use highly novel and promising Ni/Al hybrid foams which consist of standard, open-cell aluminium foams, where nanocrystalline nickel is deposited by electrodeposition as coating on the strut surface. The mechanical behaviour of cellular materials, including their behaviour under higher strain-rates, is governed by their microstructure due to the properties of the strut material, pore/strut geometry and mass distribution over the struts. Micro-inertia effects are strongly related to the microstructure. For a conclusive model, the exact real microstructure is needed. In this study a micro-focus computer tomography (μCT) system has been used for the analysis of the microstructure of the foam samples and for the development of a microstructural Finite Element (micro-FE) mesh. The microstructural FE models have been used to model the mechanical behaviour of the Ni/Al hybrid foams under dynamic loading conditions. The simulations are validated by quasi-static compression tests and dynamic split Hopkinson pressure bar tests.

  16. Causes of hatching failure in endangered birds

    PubMed Central

    Hemmings, N.; West, M.; Birkhead, T. R.

    2012-01-01

    About 10 per cent of birds' eggs fail to hatch, but the incidence of failure can be much higher in endangered species. Most studies fail to distinguish between infertility (due to a lack of sperm) and embryo mortality as the cause of hatching failure, yet doing so is crucial in order to understand the underlying problem. Using newly validated techniques to visualize sperm and embryonic tissue, we assessed the fertility status of unhatched eggs of five endangered species, including both wild and captive birds. All eggs were classified as ‘infertile’ when collected, but most were actually fertile with numerous sperm on the ovum. Eggs of captive birds had fewer sperm and were more likely to be infertile than those of wild birds. Our findings raise important questions regarding the management of captive breeding programmes. PMID:22977070

  17. The effect of artificial shrinkage and assisted hatching on the development of mouse blastocysts and cell number after vitrification

    PubMed Central

    Kim, Hye Jin; Lee, Ki Hwan; Park, Sung Baek; Choi, Young Bae

    2015-01-01

    Objective The goal of this study was to ascertain optimal assisted hatching (AH) method in frozen embryo transfer. We compared the effect of depending on whether mechanical or laser-AH was performed before or after the vitrification of embryo development rate and blastocyst cell numbers. Methods In order to induce superovulation, pregnant mare's serum gonadotropin followed by human chorionic gonadotropin were injected into 4- to 5-week-old female mice. 2-cell embryos were then collected by flushing out the oviducts. The Expanded blastocysts were recovered after the collected embryos were incubated for 48 hours, and were then subjected to artificial shrinkage (AS) and cross-mechanical AH (cMAH) or quarter-laser zona thinning-AH (qLZT-AH) were carried out using the expanded blastocysts before or after vitrification. After 48 hours of incubation, followed by vitrification and thawing (V-T), and blastocysts were fluorescence stained and observed. Results The rate of formation of hatched blastocysts after 24 and 72 hours of incubation was significantly higher in the AS/qLZT-AH/V-T group than in the other groups (p<0.05). The cell number of the inner cell mass was higher in AS/V-T/non-AH and AS/V-T/cMAH groups than those of others (p<0.05). In the control group, the number of trophectoderm and the total cell number were higher than in the AS-AH group (p<0.05). Conclusion The above results suggest that AS and AH in vitrification of expanded blastocysts lead to the more efficient formation of hatched blastocysts in mice. PMID:26473108

  18. Armstrong and Scott with Hatches Open

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronauts Neil A. Armstrong and David R. Scott sit with their spacecraft hatches open while awaiting the arrival of the recovery ship, the USS Leonard F. Mason after the successful completion of their Gemini VIII mission. They are assisted by U.S. Navy divers. The overhead view shows the Gemini 8 spacecraft with the yellow flotation collar attached to stabilize the spacecraft in choppy seas. The green marker dye is highly visible from the air and is used as a locating aid.

  19. STS-96 Astronauts Adjust Unity Hatch

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Aboard the International Space Station (ISS), astronauts Rick D. Husband and Tamara E. Jernigan adjust the hatch for the U.S. built Unity node. The task was part of an overall effort of seven crew members to prepare the existing portion of the International Space Station (ISS). Launched on May 27, 1999, aboard the Orbiter Discovery, the STS-96 mission was the second ISS assembly flight and the first shuttle mission to dock with the station.

  20. The instantaneous rate dependence in low temperature laboratory rock friction and rock deformation experiments

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.; Kronenberg, A.K.; Reinen, L.A.

    2007-01-01

    Earthquake occurrence probabilities that account for stress transfer and time-dependent failure depend on the product of the effective normal stress and a lab-derived dimensionless coefficient a. This coefficient describes the instantaneous dependence of fault strength on deformation rate, and determines the duration of precursory slip. Although an instantaneous rate dependence is observed for fracture, friction, crack growth, and low temperature plasticity in laboratory experiments, the physical origin of this effect during earthquake faulting is obscure. We examine this rate dependence in laboratory experiments on different rock types using a normalization scheme modified from one proposed by Tullis and Weeks [1987]. We compare the instantaneous rate dependence in rock friction with rate dependence measurements from higher temperature dislocation glide experiments. The same normalization scheme is used to compare rate dependence in friction to rock fracture and to low-temperature crack growth tests. For particular weak phyllosilicate minerals, the instantaneous friction rate dependence is consistent with dislocation glide. In intact rock failure tests, for each rock type considered, the instantaneous rate dependence is the same size as for friction, suggesting a common physical origin. During subcritical crack growth in strong quartzofeldspathic and carbonate rock where glide is not possible, the instantaneous rate dependence measured during failure or creep tests at high stress has long been thought to be due to crack growth; however, direct comparison between crack growth and friction tests shows poor agreement. The crack growth rate dependence appears to be higher than the rate dependence of friction and fracture by a factor of two to three for all rock types considered. Copyright 2007 by the American Geophysical Union.

  1. Influence of chick hatch time and access to feed on broiler muscle development.

    PubMed

    Powell, D J; Velleman, S G; Cowieson, A J; Singh, M; Muir, W I

    2016-06-01

    The effect of hatch time and the timing of access to feed on growth rate and breast muscle development was assessed in Ross 308 broiler chickens. Chicks were removed from the incubator upon hatching, and classified as early (EH), midterm (MH), or late (LH) hatchers, based on the duration of their incubation. Feed and water were available either immediately at hatch, or 24 h after the conclusion of the hatch period. Hatchling body weight was uniform regardless of hatch time. Subsequently, bodyweight was increased in EH compared to LH birds following immediate access to feed, until 7 d in female, and 14 d in male birds. Relative breast weight was increased until 28 d in birds with immediate access to feed, and also EH and MH birds regardless of access to feed. Pectoralis major muscle morphology and expression of the myogenic regulatory factors myogenic determination factor 1 (MYOD1) and myogenin, and the proteoglycans syndecan-4, glypican-1, and decorin were measured. Myogenin and glypican-1 stimulate satellite cell (SC) differentiation. Glypican-1 expression was unaffected by treatment. A late increase in myogenin expression was observed in MH birds with delayed access to feed, and all LH birds. Syndecan-4 and MYOD1, expressed in proliferating SC, and decorin, which stimulates satellite cell proliferation and differentiation, were variably upregulated in the first wk posthatch in the same birds. These data suggest SC were activated and proliferating, but had reduced differentiation in later hatching and feed deprived birds. Conversely, EH birds with immediate access to feed had maximal myofiber width at 7 d, while fiber width was increased in birds with immediate access to feed compared to those with delayed access to feed through 40 d of age. These results demonstrate that delaying chick access to feed for 24 h upon removal from the incubator will impair muscle growth. Additionally, hatch time influences muscle development, with accelerated muscle growth in EH and

  2. Characterization of Nonlinear Rate Dependent Response of Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Volk, Brent; Lagoudas, Dimitris C.; Chen, Yi-Chao; Whitley, Karen S.

    2007-01-01

    the material while it was above its glass transition temperature. After deforming the material to a specified applied strain, the material was then cooled to below the glass transition temperature (Tg) while retaining the deformed shape. Finally, the specimen was heated again to above the transition temperature, and the resulting shape recovery profile was measured. Results show that strain recovery occurs at a nonlinear rate with respect to time. Results also indicate that the ratio of recoverable strain/applied strain increases as the applied strain increases.

  3. EVALUATION REINFORCER MAGNITUDE AND RATE DEPENDENCY OF RESISTANCE TO CHANGE MECHANIMS

    PubMed Central

    Pinkston, Jonathan W.; Ginsburg, Brett C.; Lamb, R. J.

    2015-01-01

    In many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs, such that when schedules arrange for relatively larger reinforcer magnitude, rate dependency is attenuated compared to behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple fixed-interval schedule. Three drugs, clonidine, haloperidol, and morphine, were examined: all three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine, but those effects were not modulated by reinforcer magnitude. Additionally, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable. PMID:25115595

  4. Reinforcer magnitude and rate dependency: evaluation of resistance-to-change mechanisms.

    PubMed

    Pinkston, Jonathan W; Ginsburg, Brett C; Lamb, Richard J

    2014-10-01

    Under many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs such that when schedules arrange for relatively larger reinforcer magnitudes rate dependency is attenuated compared with behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple FI schedule. Three drugs, clonidine, haloperidol, and morphine, were examined. All three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine; however, these effects were not modulated by reinforcer magnitude. In addition, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest that a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable. PMID:25115595

  5. Timing of hatching and release of larvae by brachyuran crabs: patterns, adaptive significance and control.

    PubMed

    Christy, John H

    2011-07-01

    Most semiterrestrial, intertidal and shallow subtidal brachyuran crabs that live in tropical and warm temperate estuaries, bays and protected coasts world-wide release their planktonic larvae near the times of nocturnal high tides on the larger amplitude tides in the biweekly or monthly cycles of tidal amplitude. Crab larvae usually emigrate quickly to the sea where they develop to return as postlarvae to settle in habitats suitable for their survival. Predators of larvae are more abundant where larvae are released than where they develop, suggesting that this migration from estuaries to the sea reduces predation on larvae. Crabs with larvae that are relatively well-protected by spines and cryptic colors do not emigrate and often lack strong reproductive cycles, lending support to this explanation. Adults control the timing of the release of larvae with respect to the biweekly and monthly cycles of tidal amplitude by controlling when they court and mate and females control when development begins by controlling when they ovulate and allow their eggs to be fertilized by stored sperm. By changing the time they breed, fiddler crabs (Uca terpsichores) compensate for the effects of spatial and temporal variation in incubation temperature on development rates so that embryos are ready to hatch at the appropriate time. Control of the diel and tidal timing of hatching and of release of larvae varies with where adults live. Females of the more terrestrial species often move from protected incubation sites, sometimes far from water, and they largely control the precise time, both, of hatching and of release of larvae. Females of intertidal species also may influence when embryos begin to hatch. Upon hatching, a chemical cue is released that stimulates the female to pump her abdomen, causing rapid hatching and release of all larvae in her clutch. Embryos, rather than females, largely control hatching in subtidal species, perhaps because females incubate their eggs where they

  6. Long-range dependence and multifractality in the term structure of LIBOR interest rates

    NASA Astrophysics Data System (ADS)

    Cajueiro, Daniel O.; Tabak, Benjamin M.

    2007-01-01

    In this paper we present evidence of long-range dependence in LIBOR interest rates. We study a data set from 2000 to 2005, for six different currencies and various maturities. Empirical results suggest that the degree of long-range dependence decreases with maturity, with the exception of interest rates on Japanese Yen and on Indonesian Rupiah. Furthermore, interest rates have a multifractal nature and the degree of multifractality is much stronger for Indonesia (emerging market). These findings suggest that interest rates derivatives should take these features into account. Furthermore, fixed income risk and portfolio management should incorporate long-range dependence in the modeling of interest rates.

  7. 38 CFR 3.10 - Dependency and indemnity compensation rate for a surviving spouse.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... compensation rate for a surviving spouse. 3.10 Section 3.10 Pensions, Bonuses, and Veterans' Relief DEPARTMENT... General § 3.10 Dependency and indemnity compensation rate for a surviving spouse. (a) General determination of rate. When VA grants a surviving spouse entitlement to DIC, VA will determine the rate of...

  8. 38 CFR 3.10 - Dependency and indemnity compensation rate for a surviving spouse.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... compensation rate for a surviving spouse. 3.10 Section 3.10 Pensions, Bonuses, and Veterans' Relief DEPARTMENT... General § 3.10 Dependency and indemnity compensation rate for a surviving spouse. (a) General determination of rate. When VA grants a surviving spouse entitlement to DIC, VA will determine the rate of...

  9. 38 CFR 3.10 - Dependency and indemnity compensation rate for a surviving spouse.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... compensation rate for a surviving spouse. 3.10 Section 3.10 Pensions, Bonuses, and Veterans' Relief DEPARTMENT... General § 3.10 Dependency and indemnity compensation rate for a surviving spouse. (a) General determination of rate. When VA grants a surviving spouse entitlement to DIC, VA will determine the rate of...

  10. 38 CFR 3.10 - Dependency and indemnity compensation rate for a surviving spouse.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... compensation rate for a surviving spouse. 3.10 Section 3.10 Pensions, Bonuses, and Veterans' Relief DEPARTMENT... General § 3.10 Dependency and indemnity compensation rate for a surviving spouse. (a) General determination of rate. When VA grants a surviving spouse entitlement to DIC, VA will determine the rate of...

  11. Effects of Strain Rate Dependency of Material Properties in Low Velocity Impact

    NASA Astrophysics Data System (ADS)

    Minamoto, Hirofumi; Seifried, Robert; Eberhard, Peter; Kawamura, Shozo

    Impact processes are often analyzed using the coefficient of restitution which represents the kinetic energy loss during impact. In this paper the effect of strain rate dependency of the yield stress on the coefficient of restitution is investigated experimentally and numerically for the impact of a steel sphere against a steel rod. Finite Element simulations using strain-rate dependent material behavior are carried out. In addition, Finite Element simulations with elastic-plastic material behavior, which ignore the strain rate dependency, are carried out as well as elastic material behavior. Comparisons between the experiments and the simulations using strain-rate dependent material behavior show good agreement, and also prove the strong dependency of the coefficient of restitution on the strain rate dependency of the yield stress for steel. The results from both, the experiments and the simulations show also the strong influence of the wave propagation in the rod on the coefficient of restitution.

  12. Laboratory oviposition, fecundity and egg hatching ability of colonized Anopheles albimanus from southwestern Mexico.

    PubMed

    Ramsey, J M; Salinas, E; Lopez, J R; del Angel-Cabañas, G; Martinez, L; Bown, D N

    1988-12-01

    Fecundity, oviposition patterns and egg hatching characteristics were studied in two colonies of Anopheles albimanus isolated from the Pacific coast of southern Mexico. Fecundity was inversely proportional to the cage space available to the female and was influenced by the bloodmeal source, feeding method and previous feeding history. The length of the gonotrophic cycle decreased with succeeding experience from a mean 6.6 in the first to 2.6 days for the fifth cycle. Oviposition timing was also dependent on availability of oviposition substrate. Hatching success of eggs increased significantly when the oviposition site was witheld until 48 hr post-bloodmeal. PMID:3225569

  13. The Atmospheric General Circulation of Synchronously Rotating Planets: Dependence on Planetary Rotation Rate

    NASA Astrophysics Data System (ADS)

    Noda, S.; Ishiwatari, M.; Nakajima, K.; Takahashi, Y. O.; Morikawa, Y.; Nishizawa, S.; Hayashi, Y.-Y.

    2011-10-01

    We numerically investigate general circulation of moist atmosphere on synchronously rotating planets to examine the dependence of the atmospheric structure on planetary rotation rate. Three representative surface temperature patterns associated with different structure of heat transport appear. However, total amount of energy transport from dayside to nightside has only weak dependence on planetary rotation rate.

  14. A generalized Prandtl-Ishlinskii model for characterizing the rate-independent and rate-dependent hysteresis of piezoelectric actuators

    NASA Astrophysics Data System (ADS)

    Gan, Jinqiang; Zhang, Xianmin; Wu, Heng

    2016-03-01

    In this paper, a generalized hysteresis model is developed to describe both rate-independent and rate-dependent hysteresis in piezoelectric actuators. Based on the classical Prandtl-Ishlinskii (P-I) model, the developed model adds a quadratic polynomial and makes other small changes. When it is used to describe rate-independent hysteresis, the parameters of the model are constants, which can be identified by self-adaptive particle swarm optimization. The effectiveness of this rate-independent modified P-I model is demonstrated by comparing simulation results of the developed model and the classic Prandtl-Ishlinskii model. Simulation results suggest that the rate-independent modified P-I model can describe hysteresis more precisely. Compared with the classical P-I model, the rate-independent modified P-I model reduces modeling error by more than 50%. When it is used to describe rate-independent hysteresis, a one-side operator is adopted and the parameters are functions with input frequency. The results of the experiments and simulations have shown that the proposed models can accurately describe both rate-independent and rate-dependent hysteresis in piezoelectric actuators.

  15. A generalized Prandtl-Ishlinskii model for characterizing the rate-independent and rate-dependent hysteresis of piezoelectric actuators.

    PubMed

    Gan, Jinqiang; Zhang, Xianmin; Wu, Heng

    2016-03-01

    In this paper, a generalized hysteresis model is developed to describe both rate-independent and rate-dependent hysteresis in piezoelectric actuators. Based on the classical Prandtl-Ishlinskii (P-I) model, the developed model adds a quadratic polynomial and makes other small changes. When it is used to describe rate-independent hysteresis, the parameters of the model are constants, which can be identified by self-adaptive particle swarm optimization. The effectiveness of this rate-independent modified P-I model is demonstrated by comparing simulation results of the developed model and the classic Prandtl-Ishlinskii model. Simulation results suggest that the rate-independent modified P-I model can describe hysteresis more precisely. Compared with the classical P-I model, the rate-independent modified P-I model reduces modeling error by more than 50%. When it is used to describe rate-independent hysteresis, a one-side operator is adopted and the parameters are functions with input frequency. The results of the experiments and simulations have shown that the proposed models can accurately describe both rate-independent and rate-dependent hysteresis in piezoelectric actuators. PMID:27036808

  16. Effects of hatching time for larval ambystomatid salamanders

    USGS Publications Warehouse

    Boone, M.D.; Scott, D.E.; Niewiarowski, P.H.

    2002-01-01

    In aquatic communities, the phenology of breeding may influence species interactions. In the early-breeding marbled salamander, Ambystoma opacum, timing of pond filling may determine whether interactions among larvae are competitive or predatory. The objectives of our studies were to determine how time of egg hatching affected size, larval period, and survival to metamorphosis in A. opacum, and if early-hatching in A. opacum influenced the competitive and predator-prey relationships with smaller larvae of the mole salamander, Ambystoma talpoideum. Salamander larvae were reared from hatching through metamorphosis in large, outdoor enclosures located in a natural temporary pond in Aiken County, South Carolina, in two experiments. In study 1, we reared early- and late-hatching A. opacum larvae separately from hatching through metamorphosis. In study 2, we examined how early- versus late-hatching A. opacum affected a syntopic species, A. talpoideum. In general, early-hatching A. opacum were larger and older at metamorphosis, had greater survival, and left the pond earlier than late-hatching larvae. Ambystoma talpoideum reared in the presence of early-hatching A. opacum had lower survival than in controls, suggesting that A. opacum may predate upon A. talpoideum when they gain a growth advantage over later-hatching larvae. Our studies demonstrate that time of pond filling and phenology of breeding may influence population dynamics and alter the nature of relationships that develop among species.

  17. 38 CFR 3.10 - Dependency and indemnity compensation rate for a surviving spouse.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Dependency and indemnity compensation rate for a surviving spouse. 3.10 Section 3.10 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS ADJUDICATION Pension, Compensation, and Dependency and Indemnity Compensation General § 3.10 Dependency and...

  18. Genetic similarity and hatching success in birds.

    PubMed Central

    Spottiswoode, Claire; Møller, Anders Pape

    2004-01-01

    The ecological correlates of fitness costs of genetic similarity in free-living, large populations of organisms are poorly understood. Using a dataset of genetic similarity as reflected by band-sharing coefficients of minisatellites, we show that bird species with higher genetic similarity experience elevated hatching failure of eggs, increasing by a factor of six across 99 species. Island distributions and cooperative breeding systems in particular were associated with elevated genetic similarity. These findings provide comparative evidence of detrimental fitness consequences of high genetic similarity across a wide range of species, and help to identify ecological factors potentially associated with increased risk of extinction. PMID:15058437

  19. Investigating embryo deaths and hatching failure.

    PubMed

    Rideout, Bruce A

    2012-05-01

    Investigation of all embryo and neonatal mortalities is essential for optimizing productivity in artificial incubation and hand rearing programs. Because artificial incubation is a complex process with many variables, thorough and systematic evaluations are necessary to identify potential problems. Every step of the process from egg lay through incubation and hatching should be evaluated in conjunction with comprehensive data on management of the breeding population. The most common sources of significant problems include nutrition and management of the breeding population, insufficient parental incubation prior to artificial incubation, abnormal egg weight loss during incubation, and infections of the yolk sac or umbilicus. PMID:22640533

  20. A rate-dependent microcrack-bridging model that can explain the strain rate dependency of cortical bone apparent yield strength.

    PubMed

    Yeni, Yener N; Fyhrie, David P

    2003-09-01

    Although there are empirical correlations between strain rate, cortical and cancellous bone apparent stiffness, apparent yield strength, apparent ultimate strength and cortical bone fracture toughness, a mechanistic description for these phenomena is lacking. Microcracking is a major mechanism in cortical and cancellous bone failure, however, microdamage content alone cannot explain the strain rate dependence of bone strength without considering time-dependent behavior of the crack. Using a rate-dependent model of a fiber-bridged microcrack and data from the literature, we demonstrate that the experimental apparent yield strength of bone can be predicted directly from measurements of apparent moduli of elasticity of bone constituents and failure strain of the collagenous matrix. Yield strength predictions for estrogen depleted bone were made using the model and data from ovariectomized sheep. It was predicted that the yield strength of estrogen-deficient bone is comparable to that of normal bone within strain rates associated with physiological activities. For high strain rates, however, the strength of estrogen-depleted bone was predicted to be much weaker than normals suggesting a higher fracture risk due to impact from falls, for individuals with estrogen-depleted bones such as in post-menopausal osteoporosis. PMID:12893043

  1. Heart rate variability during sleep in detoxified alcohol-dependent males: A comparison with healthy controls

    PubMed Central

    Ganesha, Suhas; Thirthalli, Jagadisha; Muralidharan, Kesavan; Benegal, Vivek; Gangadhar, Bangalore N.

    2013-01-01

    Context: Alcohol dependence can lead to autonomic neuropathy resulting in increased cardiac morbidity and mortality. This has previously been evaluated using heart-rate variability. Aims: We compared sleep heart-rate variability of alcohol-dependent patients with that of healthy controls in this study. Settings and Design: This study was conducted at NIMHANS, Bangalore. A case control study design was adopted. Materials and Methods: Sleep heart-rate variability of 20 male alcohol-dependent inpatients was recorded on the 5th day after detoxification. Sleep heart-rate variability was also recorded in 18 age- and gender-matched healthy controls. Statistical Analysis: The groups were compared using t-test for continuous variables and Chi-squared test for discrete variables. Results: Both time and frequency domain measures were significantly lower in the patients as compared to the controls, indicating decreased HRV in alcohol-dependent individuals. Conclusions: Decreased HRV in alcohol dependence indicates potential autonomic neuropathy. PMID:23825854

  2. Growth-rate dependent global effects on gene expression in bacteria

    PubMed Central

    Klumpp, Stefan; Zhang, Zhongge; Hwa, Terence

    2010-01-01

    Summary Bacterial gene expression depends not only on specific regulations but also directly on bacterial growth, because important global parameters such as the abundance of RNA polymerases and ribosomes are all growth-rate dependent. Understanding these global effects is necessary for a quantitative understanding of gene regulation and for the robust design of synthetic genetic circuits. The observed growth-rate dependence of constitutive gene expression can be explained by a simple model using the measured growth-rate dependence of the relevant cellular parameters. More complex growth dependences for genetic circuits involving activators, repressors and feedback control were analyzed, and salient features were verified experimentally using synthetic circuits. The results suggest a novel feedback mechanism mediated by general growth-dependent effects and not requiring explicit gene regulation, if the expressed protein affects cell growth. This mechanism can lead to growth bistability and promote the acquisition of important physiological functions such as antibiotic resistance and tolerance (persistence). PMID:20064380

  3. Reinforcement magnitude modulation of rate dependent effects in pigeons and rats.

    PubMed

    Ginsburg, Brett C; Pinkston, Jonathan W; Lamb, R J

    2011-08-01

    Response rate can influence the behavioral effects of many drugs. Reinforcement magnitude may also influence drug effects. Further, reinforcement magnitude can influence rate-dependent effects. For example, in an earlier report, we showed that rate-dependent effects of two antidepressants depended on reinforcement magnitude. The ability of reinforcement magnitude to interact with rate-dependency has not been well characterized. It is not known whether our previous results are specific to antidepressants or generalize to other drug classes. Here, we further examine rate-magnitude interactions by studying effects of two stimulants (d-amphetamine [0.32-5.6 mg/kg] and cocaine [0.32-10 mg/kg]) and two sedatives (chlordiazepoxide [1.78-32 mg/kg] and pentobarbital [1.0-17.8 mg/kg]) in pigeons responding under a 3-component multiple fixed-interval (FI) 300-s schedule maintained by 2-, 4-, or 8-s of food access. We also examine the effects of d-amphetamine [0.32-3.2 mg/kg] and pentobarbital [1.8-10 mg/kg] in rats responding under a similar multiple FI300-s schedule maintained by 2- or 10- food pellet (45 mg) delivery. In pigeons, cocaine and, to a lesser extent, chlordiazepoxide exerted rate-dependent effects that were diminished by increasing durations of food access. The relationship was less apparent for pentobarbital, and not present for d-amphetamine. In rats, rate-dependent effects of pentobarbital and d-amphetamine were not modulated by reinforcement magnitude. In conclusion, some drugs appear to exert rate-dependent effect which are diminished when reinforcement magnitude is relatively high. Subsequent analysis of the rate-dependency data suggest the effects of reinforcement magnitude may be due to a diminution of drug-induced increases in low-rate behavior that occurs early in the fixed-interval. PMID:21707192

  4. Divergent selection for shape of growth curve in Japanese quail. 6. Hatching time, hatchability and embryo mortality.

    PubMed

    Hyánková, L; Starosta, F

    2012-01-01

    1. Hatching time, hatchability of fertile eggs and embryo mortality under standard egg storage (1 or 5 days at 12 ± 1°C and 55% relative humidity) and incubation conditions (37.5 ± 0.2°C and 50% relative humidity) were analysed in lines long-term selected for high (HG) and low (LG) relative weight gain between 11 and 28 d of age, respectively, and constant body weight at 49 d of age. 2. Egg storage duration did not have an effect on average hatching time. LG quail, characterised by a fast postnatal growth rate immediately after hatching, hatched earlier than HG quail with a low early growth rate (about 391 vs. 406 h after egg setting, respectively). 3. In contrast to hatching time, the hatchability of fertile eggs was influenced by line as well as egg storage duration. Extended storage decreased hatching success in both lines. However, LG eggs exhibited a higher hatchability than HG eggs (1 d storage: 96.0 vs. 82.5%; 5 d storage: 88.7 vs. 72.7%, respectively). 4. Lower hatchability resulted mostly from a higher frequency of embryo death during early (up to d 7) and late (d 14 and later) phases of incubation. 5. An inadequate nutrient supply to embryos in consequence of developmental delay seems to be a key factor decreasing viability of embryos during incubation. PMID:23281752

  5. Time-dependent Kramers escape rate in overdamped system with power-law distribution

    NASA Astrophysics Data System (ADS)

    Zhou, Yanjun; Yin, Cangtao

    2016-05-01

    The probability distribution of Brownian particles moving in an overdamped complex system follows the generalized Smoluchowski equation, which can be rigorously proven that the exact time-dependent solution for this equation follows Tsallis form. Time-dependent escape rate in overdamped system with power-law distributions is then established based on the flux over population theory. The stationary state escape rate in overdamped system with power-law distribution which has been obtained before based on mean first passage time theory is recovered from time-dependent escape rate as time toward infinity.

  6. Time-dependent estimates of molecular evolutionary rates: evidence and causes.

    PubMed

    Ho, Simon Y W; Duchêne, Sebastián; Molak, Martyna; Shapiro, Beth

    2015-12-01

    We are writing in response to a recent critique by Emerson & Hickerson (2015), who challenge the evidence of a time-dependent bias in molecular rate estimates. This bias takes the form of a negative relationship between inferred evolutionary rates and the ages of the calibrations on which these estimates are based. Here, we present a summary of the evidence obtained from a broad range of taxa that supports a time-dependent bias in rate estimates, with a consideration of the potential causes of these observed trends. We also describe recent progress in improving the reliability of evolutionary rate estimation and respond to the concerns raised by Emerson & Hickerson (2015) about the validity of rates estimated from time-structured sequence data. In doing so, we hope to dispel some misconceptions and to highlight several research directions that will improve our understanding of time-dependent biases in rate estimates. PMID:26769402

  7. Yield strength dependence on strain rate of molybdenum-alloy nanofibers

    SciTech Connect

    Loya, P. E.; Peng, C.; Zhang, P.; Zhang, J.; Lou, J.; Xia, Y. Z.; Bei, H.; George, E. P.; Gao, Y. F.

    2014-06-23

    The yield strength dependence on strain rate was studied for molybdenum-alloy nanofibers with varying initial dislocation density at three different pre-strain levels. In-situ tensile experiments at three displacement rates were carried out in a scanning electron microscope. Yield strength and its scatter decreased as a function of the pre-strain level for different displacement rates. A statistical model was used to analyze the results, and a negative strain rate dependence was inferred from the yield experiments. This finding suggests the need for theoretical investigations since classical models such as dynamic strain aging may have limitations at such nanoscales.

  8. Displacement rate dependence of irradiation creep as predicted by the production bias model

    SciTech Connect

    Woo, C.H.

    1996-04-01

    Recently, it has been shown that the non-swelling component of irradiation creep of austenitic stainless steels is relatively independent of temperature but is sensitive to the displacement rate. An earlier model of Lewthwaite and Mosedale anticipated the sensitivity of displacement rate and attributed it to the flux sensitivity of point defect recombination. The point-defect recombination process does not yield the observed temperature dependence, however, although it does predict an inverse dependence of the creep rate on the square root of the displacement rate that was experimentally observed at relatively low temperatures.

  9. Rate dependent inelastic behavior of polycrystalline solids using a dislocation model

    SciTech Connect

    Werne, R.W.; Kelly, J.M.

    1980-02-26

    A rate dependent theory of polycrystalline plasticity is presented in which the solid is modeled as an isotropic continuum with internal variables. The rate of plastic deformation is shown to be a function of the deviatoric portion of the Cauchy stress tensor as well as two scalar internal variables. The scalar internal variables, which are the dislocation density and mobile fraction, are governed by rate equations which reflect the evolution of microstructural processes. The model has been incorporated into a two dimensional finite element code and several example multidimensional problems are presented which exhibit the rate dependence of the material model.

  10. Temperature-dependent reaction-rate expression for oxygen recombination at Shuttle entry conditions

    NASA Technical Reports Server (NTRS)

    Zoby, E. V.; Simmonds, A. L.; Gupta, R. N.

    1984-01-01

    A temperature-dependent oxygen surface reaction-rate coefficient has been determined from experimental STS-2 heating and wall temperature data at altitudes of 77.91 km, 74.98 km, and 71.29 km. The coefficient is presented in an Arrhenius form and is shown to be less temperature dependent than previous results. Finite-rate viscous-shock-layer heating rates based on this present expression have been compared with predicted heating rates using the previous rate coefficients and with experimental heating data obtained over an extensive range of STS-2 and STS-3 entry conditions. A substantial improvement is obtained in comparison of experimental data and predicted heating rates using the present oxygen reaction-rate expression.

  11. Coordinate-dependent diffusion coefficients: Decay rate in open quantum systems

    SciTech Connect

    Sargsyan, V. V.; Palchikov, Yu. V.; Antonenko, N. V.; Kanokov, Z.; Adamian, G. G.

    2007-06-15

    Based on a master equation for the reduced density matrix of an open quantum collective system, the influence of coordinate-dependent microscopical diffusion coefficients on the decay rate from a metastable state is treated. For various frictions and temperatures larger than a crossover temperature, the quasistationary decay rates obtained with the coordinate-dependent microscopical set of diffusion coefficients are compared with those obtained with the coordinate-independent microscopical set of diffusion coefficients and coordinate-independent and -dependent phenomenological sets of diffusion coefficients. Neglecting the coordinate dependence of diffusion coefficients, one can strongly overestimate or underestimate the decay rate at low temperature. The coordinate-dependent phenomenological diffusion coefficient in momentum are shown to be suitable for applications.

  12. Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

    SciTech Connect

    Nguyen, Trung Dung; Gu, YuanTong

    2014-05-05

    Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

  13. Current dependence of spin torque switching rate based on Fokker-Planck approach

    SciTech Connect

    Taniguchi, Tomohiro Imamura, Hiroshi

    2014-05-07

    The spin torque switching rate of an in-plane magnetized system in the presence of an applied field is derived by solving the Fokker-Planck equation. It is found that three scaling currents are necessary to describe the current dependence of the switching rate in the low-current limit. The dependences of these scaling currents on the applied field strength are also studied.

  14. PRESSURE AND TEMPERATURE DEPENDENT DEFLAGRATION RATE MEASUREMENTS OF LLM-105 AND TATB BASED EXPLOSIVES

    SciTech Connect

    Glascoe, E A; Tan, N; Koerner, J; Lorenz, K T; Maienschein, J L

    2009-11-10

    The pressure dependent deflagration rates of LLM-105 and TATB based formulations were measured in the LLNL high pressure strand burner. The role of binder amount, explosive type, and thermal damage and their effects on the deflagration rate will be discussed. Two different formulations of LLM-105 and three formulations of TATB were studied and results indicate that binder amount and type play a minor role in the deflagration behavior. This is in sharp contrast to the HMX based formulations which strongly depend on binder amount and type. The effect of preheating these samples was considerably more dramatic. In the case of LLM-105, preheating the sample appears to have little effect on the deflagration rate. In contrast, preheating TATB formulations causes the deflagration rate to accelerate and become erratic. The thermal and mechanical properties of these formulations will be discussed in the context of their pressure and temperature dependent deflagration rates.

  15. Order in the absence of an effect: Identifying rate-dependent relationships.

    PubMed

    Snider, Sarah E; Quisenberry, Amanda J; Bickel, Warren K

    2016-06-01

    The heterogeneity of group data can obscure a significant effect of an intervention due to differential baseline scores. Instead of discarding the seemingly heterogeneous response set, an orderly lawful relationship could be present. Rate dependence describes a pattern between a baseline and the change in that baseline following some intervention. To highlight the importance of analyzing data from a rate-dependent perspective, we (1) briefly review research illustrating that rate-dependent effects can be observed in response to both drug and non-drug interventions in varied schedules of reinforcement in clinical and preclinical populations; (2) observe that the process of rate-dependence likely requires multiple parts of a system operating simultaneously to evoke differential responding as a function of baseline; and (3) describe several statistical methods for consideration and posit that Oldham's correlation is the most appropriate for rate-dependent analyses. Finally, we propose future applications for these analyses in which the level of baseline behavior exhibited prior to an intervention may determine the magnitude and direction of behavior change and can lead to the identification of subpopulations that would be benefitted. In sum, rate dependence is an invaluable perspective to examine data following any intervention in order to identify previously overlooked results. PMID:27001350

  16. Effect of laser-assisted multi-point zona thinning on development and hatching of cleavage embryos in mice

    PubMed Central

    Lee, Young Seok; Park, Min Jung; Park, Sea Hee; Koo, Ja Seong

    2015-01-01

    Objective This study aimed to examine the effect of laser-assisted zona thinning (LAZT) at one or four-points on the blastocyst formation and hatching process in mice with respect to female age. Methods Eight-cell or morula embryos collected from superovulated C57BL female mice with different ages (6-11 and 28-31 weeks) were treated with LAZT at one-point (LAZT1) or four-points (LAZT4). The zona pellucida was thinned to more than 70% of its initial thickness by making two holes of 15-20 µm. Results In the young mice, LAZT resulted in a significant increase in early hatching and hatching rates compared to the control group (p<0.05). However, in the old mice, LAZT significantly increased blastocyst formation as well as early hatching and hatching compared to the controls (p<0.05). These effects were more remarkable in LAZT4 than in LAZT1 and in aged mice than in young ones. Conclusion These results show that multi-point LAZT leads to a significant improvement of blastocyst formation and hatching in mice compared to controls. PMID:26161333

  17. Semiclassical Study of the Wave Vector Dependence of the Interband Impact Ionization Rate in Bulk Silicon

    NASA Technical Reports Server (NTRS)

    Wang, Yang; Brennan, Kevin F.

    1994-01-01

    We present calculations of the interband impact ionization rate calculated using a wave vector dependent (k-dependent) semiclassical formulation of the transition rate. The transition rate is determined using Fermi's golden rule from a two-body screened Coulomb interaction assuming energy and momentum conservation. The transition rate is calculated for the first two conduction bands of silicon by numerically integrating over the full Brillouin zone. The overlap integrals in the expression for the transition rate are determined numerically using a 15 band k-p calculation. It is found that the transition rate depends strongly on the initiating electron wave vector (k vector) and that the transition rate is greatest for electrons originating within the second conduction band than the first conduction band. An ensemble Monte Carlo simulation, which includes the numerically determined ionization transition rate as well as the full details of the first two conduction bands, is used to calculate the total impact ionization rate in bulk silicon. Good agreement with the experimentally determined electron ionization rate data is obtained.

  18. Participation Rates in the Aid to Families with Dependent Children Program: Trends for 1967 through 1984.

    ERIC Educational Resources Information Center

    Ruggles, Patricia; Michel, Richard C.

    This report examines participation rates in the Aid to Families with Dependent Children (AFDC) program. TRIM2, a microsimulation model that simulated the eligibility and benefit rules of the AFDC program on a state-by-state basis, showed that there had been a dramatic decline after 1981 in the rate at which AFDC families were applying for and…

  19. Effect of storage environment on hatching of Globodera ellingtonae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Globodera spp. eggs go through a diapause stage in which development remains dormant until favorable hatching conditions are reached. Because of the regulatory concerns with Globodera spp., it is often only possible to rear eggs for research in the greenhouse. However, hatch is often lower for green...

  20. 29 CFR 780.211 - Contract production of hatching eggs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Contract production of hatching eggs. 780.211 Section 780... eggs. It is common practice for hatcherymen to enter into arrangements with farmer poultry raisers for the production of hatching eggs which the hatchery agrees to buy. Ordinarily, the farmer furnishes...

  1. 29 CFR 780.211 - Contract production of hatching eggs.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false Contract production of hatching eggs. 780.211 Section 780... eggs. It is common practice for hatcherymen to enter into arrangements with farmer poultry raisers for the production of hatching eggs which the hatchery agrees to buy. Ordinarily, the farmer furnishes...

  2. 29 CFR 780.211 - Contract production of hatching eggs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false Contract production of hatching eggs. 780.211 Section 780... eggs. It is common practice for hatcherymen to enter into arrangements with farmer poultry raisers for the production of hatching eggs which the hatchery agrees to buy. Ordinarily, the farmer furnishes...

  3. 29 CFR 780.211 - Contract production of hatching eggs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false Contract production of hatching eggs. 780.211 Section 780... eggs. It is common practice for hatcherymen to enter into arrangements with farmer poultry raisers for the production of hatching eggs which the hatchery agrees to buy. Ordinarily, the farmer furnishes...

  4. 29 CFR 780.211 - Contract production of hatching eggs.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false Contract production of hatching eggs. 780.211 Section 780... eggs. It is common practice for hatcherymen to enter into arrangements with farmer poultry raisers for the production of hatching eggs which the hatchery agrees to buy. Ordinarily, the farmer furnishes...

  5. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Hatches and coamings. 174.220 Section 174.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches...

  6. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Hatches and coamings. 174.220 Section 174.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches...

  7. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Hatches and coamings. 174.220 Section 174.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches...

  8. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Hatches and coamings. 174.220 Section 174.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches...

  9. 14. VIEW OF NORTHSOUTH ROAD WHICH PARALLELS ROAD TO HATCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. VIEW OF NORTH-SOUTH ROAD WHICH PARALLELS ROAD TO HATCH ADIT (FEATURE B-28). NOTE MODERN 'LAY DOWN' FENCE ON ROAD. ROAD LIES TO THE WEST OF THE HATCH ADIT AND PHOTOGRAPH IS VIEW TO THE SOUTH. (OCTOBER, 1995) - Nevada Lucky Tiger Mill & Mine, East slope of Buckskin Mountain, Paradise Valley, Humboldt County, NV

  10. 46 CFR 174.220 - Hatches and coamings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Hatches and coamings. 174.220 Section 174.220 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Offshore Supply Vessels § 174.220 Hatches...

  11. 46 CFR 131.893 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Watertight doors and watertight hatches. 131.893 Section... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.893 Watertight doors and watertight hatches. Each watertight door in a bulkhead that must be watertight in compliance with the requirements...

  12. 46 CFR 131.893 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Watertight doors and watertight hatches. 131.893 Section... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.893 Watertight doors and watertight hatches. Each watertight door in a bulkhead that must be watertight in compliance with the requirements...

  13. 46 CFR 131.893 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Watertight doors and watertight hatches. 131.893 Section... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.893 Watertight doors and watertight hatches. Each watertight door in a bulkhead that must be watertight in compliance with the requirements...

  14. 46 CFR 122.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Watertight doors and watertight hatches. 122.610 Section... Markings Required § 122.610 Watertight doors and watertight hatches. Watertight doors and watertight...: “WATERTIGHT DOOR—KEEP CLOSED” or “WATERTIGHT HATCH—KEEP CLOSED”, unless such markings are deemed...

  15. 46 CFR 122.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Watertight doors and watertight hatches. 122.610 Section... Markings Required § 122.610 Watertight doors and watertight hatches. Watertight doors and watertight...: “WATERTIGHT DOOR—KEEP CLOSED” or “WATERTIGHT HATCH—KEEP CLOSED”, unless such markings are deemed...

  16. 46 CFR 122.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Watertight doors and watertight hatches. 122.610 Section... Markings Required § 122.610 Watertight doors and watertight hatches. Watertight doors and watertight...: “WATERTIGHT DOOR—KEEP CLOSED” or “WATERTIGHT HATCH—KEEP CLOSED”, unless such markings are deemed...

  17. 46 CFR 122.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Watertight doors and watertight hatches. 122.610 Section... Markings Required § 122.610 Watertight doors and watertight hatches. Watertight doors and watertight...: “WATERTIGHT DOOR—KEEP CLOSED” or “WATERTIGHT HATCH—KEEP CLOSED”, unless such markings are deemed...

  18. 46 CFR 122.610 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Watertight doors and watertight hatches. 122.610 Section... Markings Required § 122.610 Watertight doors and watertight hatches. Watertight doors and watertight...: “WATERTIGHT DOOR—KEEP CLOSED” or “WATERTIGHT HATCH—KEEP CLOSED”, unless such markings are deemed...

  19. 46 CFR 131.893 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Watertight doors and watertight hatches. 131.893 Section... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.893 Watertight doors and watertight hatches. Each watertight door in a bulkhead that must be watertight in compliance with the requirements...

  20. 46 CFR 131.893 - Watertight doors and watertight hatches.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Watertight doors and watertight hatches. 131.893 Section... OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.893 Watertight doors and watertight hatches. Each watertight door in a bulkhead that must be watertight in compliance with the requirements...

  1. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory.

    PubMed

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth

    2016-09-01

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals. PMID:27608987

  2. Reaction rate and composition dependence of the stability of thermonuclear burning on accreting neutron stars

    SciTech Connect

    Keek, L.; Cyburt, R. H.; Heger, A.

    2014-06-01

    The stability of thermonuclear burning of hydrogen and helium accreted onto neutron stars is strongly dependent on the mass accretion rate. The burning behavior is observed to change from Type I X-ray bursts to stable burning, with oscillatory burning occurring at the transition. Simulations predict the transition at a 10 times higher mass accretion rate than observed. Using numerical models we investigate how the transition depends on the hydrogen, helium, and CNO mass fractions of the accreted material, as well as on the nuclear reaction rates of 3α and the hot-CNO breakout reactions {sup 15}O(α, γ){sup 19}Ne and {sup 18}Ne(α, p){sup 21}Na. For a lower hydrogen content the transition is at higher accretion rates. Furthermore, most experimentally allowed reaction rate variations change the transition accretion rate by at most 10%. A factor 10 decrease of the {sup 15}O(α, γ){sup 19}Ne rate, however, produces an increase of the transition accretion rate of 35%. None of our models reproduce the transition at the observed rate, and depending on the true {sup 15}O(α, γ){sup 19}Ne reaction rate, the actual discrepancy may be substantially larger. We find that the width of the interval of accretion rates with marginally stable burning depends strongly on both composition and reaction rates. Furthermore, close to the stability transition, our models predict that X-ray bursts have extended tails where freshly accreted fuel prolongs nuclear burning.

  3. MicroRNA-276 promotes egg-hatching synchrony by up-regulating brm in locusts.

    PubMed

    He, Jing; Chen, Qianquan; Wei, Yuanyuan; Jiang, Feng; Yang, Meiling; Hao, Shuguang; Guo, Xiaojiao; Chen, Dahua; Kang, Le

    2016-01-19

    Developmental synchrony, the basis of uniform swarming, migration, and sexual maturation, is an important strategy for social animals to adapt to variable environments. However, the molecular mechanisms underlying developmental synchrony are largely unexplored. The migratory locust exhibits polyphenism between gregarious and solitarious individuals, with the former displaying more synchronous sexual maturation and migration than the latter. Here, we found that the egg-hatching time of gregarious locusts was more uniform compared with solitarious locusts and that microRNA-276 (miR-276) was expressed significantly higher in both ovaries and eggs of gregarious locusts than in solitarious locusts. Interestingly, inhibiting miR-276 in gregarious females and overexpressing it in solitarious females, respectively, caused more heterochronic and synchronous hatching of progeny eggs. Moreover, miR-276 directly targeted a transcription coactivator gene, brahma (brm), resulting in its up-regulation. Knockdown of brm not only resulted in asynchronous egg hatching in gregarious locusts but also impaired the miR-276-induced synchronous egg hatching in solitarious locusts. Mechanistically, miR-276 mediated brm activation in a manner that depended on the secondary structure of brm, namely, a stem-loop around the binding site of miR-276. Collectively, our results unravel a mechanism by which miR-276 enhances brm expression to promote developmental synchrony and provide insight into regulation of developmental homeostasis and population sustaining that are closely related to biological synchrony. PMID:26729868

  4. MicroRNA-276 promotes egg-hatching synchrony by up-regulating brm in locusts

    PubMed Central

    He, Jing; Chen, Qianquan; Wei, Yuanyuan; Jiang, Feng; Yang, Meiling; Hao, Shuguang; Guo, Xiaojiao; Chen, Dahua; Kang, Le

    2016-01-01

    Developmental synchrony, the basis of uniform swarming, migration, and sexual maturation, is an important strategy for social animals to adapt to variable environments. However, the molecular mechanisms underlying developmental synchrony are largely unexplored. The migratory locust exhibits polyphenism between gregarious and solitarious individuals, with the former displaying more synchronous sexual maturation and migration than the latter. Here, we found that the egg-hatching time of gregarious locusts was more uniform compared with solitarious locusts and that microRNA-276 (miR-276) was expressed significantly higher in both ovaries and eggs of gregarious locusts than in solitarious locusts. Interestingly, inhibiting miR-276 in gregarious females and overexpressing it in solitarious females, respectively, caused more heterochronic and synchronous hatching of progeny eggs. Moreover, miR-276 directly targeted a transcription coactivator gene, brahma (brm), resulting in its up-regulation. Knockdown of brm not only resulted in asynchronous egg hatching in gregarious locusts but also impaired the miR-276–induced synchronous egg hatching in solitarious locusts. Mechanistically, miR-276 mediated brm activation in a manner that depended on the secondary structure of brm, namely, a stem-loop around the binding site of miR-276. Collectively, our results unravel a mechanism by which miR-276 enhances brm expression to promote developmental synchrony and provide insight into regulation of developmental homeostasis and population sustaining that are closely related to biological synchrony. PMID:26729868

  5. On the Firing Rate Dependency of the Phase Response Curve of Rat Purkinje Neurons In Vitro

    PubMed Central

    Couto, João; Linaro, Daniele; De Schutter, E; Giugliano, Michele

    2015-01-01

    Synchronous spiking during cerebellar tasks has been observed across Purkinje cells: however, little is known about the intrinsic cellular mechanisms responsible for its initiation, cessation and stability. The Phase Response Curve (PRC), a simple input-output characterization of single cells, can provide insights into individual and collective properties of neurons and networks, by quantifying the impact of an infinitesimal depolarizing current pulse on the time of occurrence of subsequent action potentials, while a neuron is firing tonically. Recently, the PRC theory applied to cerebellar Purkinje cells revealed that these behave as phase-independent integrators at low firing rates, and switch to a phase-dependent mode at high rates. Given the implications for computation and information processing in the cerebellum and the possible role of synchrony in the communication with its post-synaptic targets, we further explored the firing rate dependency of the PRC in Purkinje cells. We isolated key factors for the experimental estimation of the PRC and developed a closed-loop approach to reliably compute the PRC across diverse firing rates in the same cell. Our results show unambiguously that the PRC of individual Purkinje cells is firing rate dependent and that it smoothly transitions from phase independent integrator to a phase dependent mode. Using computational models we show that neither channel noise nor a realistic cell morphology are responsible for the rate dependent shift in the phase response curve. PMID:25775448

  6. Effect of microstructure on anomalous strain-rate-dependent behaviour of bacterial cellulose hydrogel.

    PubMed

    Gao, Xing; Shi, Zhijun; Lau, Andrew; Liu, Changqin; Yang, Guang; Silberschmidt, Vadim V

    2016-05-01

    This study is focused on anomalous strain-rate-dependent behaviour of bacterial cellulose (BC) hydrogel that can be strain-rate insensitive, hardening, softening, or strain-rate insensitive in various ranges of strain rate. BC hydrogel consists of randomly distributed nanofibres and a large content of free water; thanks to its ideal biocompatibility, it is suitable for biomedical applications. Motivated by its potential applications in complex loading conditions of body environment, its time-dependent behaviour was studied by means of in-aqua uniaxial tension tests at constant temperature of 37 °C at various strain rates ranging from 0.000 1s(-1) to 0.3s(-1). Experimental results reflect anomalous strain-rate-dependent behaviour that was not documented before. Micro-morphological observations allowed identification of deformation mechanisms at low and high strain rates in relation to microstructural changes. Unlike strain-rate softening behaviours in other materials, reorientation of nanofibres and kinematics of free-water flow dominate the softening behaviour of BC hydrogel at high strain rates. PMID:26952406

  7. Displacement damage rate dependence of defect cluster formation in α-Fe during irradiation

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Morishita, K.; Yamamoto, Y.; Hamaguchi, D.; Tanigawa, H.

    2013-05-01

    Formation kinetics of defect clusters in pure iron during irradiation has been numerically investigated by reaction rate theory, with focusing on nucleation process of vacancy clusters (voids) and self-interstitial-atoms (SIA) clusters under a wide range of atomic displacement damage rate (dpa rate) and temperature conditions. In the rate theory model, the size dependence of thermal stability of a defect cluster is treated for a wide range of cluster size. The numerical analysis shows that the nucleation processes of voids and SIA-clusters are quite different from each other. As to the voids, the nucleation rate of voids depends much on temperature and dpa rate, and has the individual peak temperature for each dpa rate, during which the peak temperature increases with increasing dpa rate. This tendency for void nucleation is similar to that for void swelling observed in experiments. As to the SIA-clusters, the nucleation rate of SIA-clusters does not depend much on temperature and has no peak temperatures because of the relatively high thermal stability of an SIA-cluster, indicating that the conventional model (di-interstitial model) is applicable to describe the nucleation of SIA-clusters in a wide range of temperature.

  8. Physical mechanisms underlying the strain-rate-dependent mechanical behavior of kangaroo shoulder cartilage

    NASA Astrophysics Data System (ADS)

    Thibbotuwawa, Namal; Oloyede, Adekunle; Li, Tong; Singh, Sanjleena; Senadeera, Wijitha; Gu, YuanTong

    2015-09-01

    Due to anatomical and biomechanical similarities to human shoulder, kangaroo was chosen as a model to study shoulder cartilage. Comprehensive enzymatic degradation and indentation tests were applied on kangaroo shoulder cartilage to study mechanisms underlying its strain-rate-dependent mechanical behavior. We report that superficial collagen plays a more significant role than proteoglycans in facilitating strain-rate-dependent behavior of the kangaroo shoulder cartilage. By comparing the mechanical properties of degraded and normal cartilages, it was noted that proteoglycan and collagen degradation significantly compromised strain-rate-dependent mechanical behavior of the cartilage. Superficial collagen contributed equally to the tissue behavior at all strain-rates. This is different to the studies reported on knee cartilage and confirms the importance of superficial collagen on shoulder cartilage mechanical behavior. A porohyperelastic numerical model also indicated that collagen disruption would lead to faster damage of the shoulder cartilage than when proteoglycans are depleted.

  9. Pairing context determines condition-dependence of song rate in a monogamous passerine bird

    PubMed Central

    David, Morgan; Auclair, Yannick; Dall, Sasha R. X.; Cézilly, Frank

    2013-01-01

    Condition-dependence of male ornaments is thought to provide honest signals on which females can base their sexual choice for genetic quality. Recent studies show that condition-dependence patterns can vary within populations. Although long-term association is thought to promote honest signalling, no study has explored the influence of pairing context on the condition-dependence of male ornaments. In this study, we assessed the influence of natural variation in body condition on song rate in zebra finches (Taeniopygia guttata) in three different situations: during short and long encounters with an unfamiliar female, and within heterosexual mated pairs. We found consistent individual differences in male directed and undirected song rate. Moreover, body condition had a positive effect on song rate in paired males. However, male song rate was not influenced by body condition during short or long encounters with unfamiliar females. Song rate appears to be an unreliable signal of condition to prospective females as even poor-condition birds can cheat and sing at a high rate. By contrast, paired females can reliably use song rate to assess their mate's body condition, and possibly the genetic quality. We propose that species' characteristics, such as mating system, should be systematically taken into account to generate relevant hypotheses about the evolution of condition-dependent male ornaments. PMID:23256191

  10. Place dependent stimulation rates improve pitch perception in cochlear implantees with single-sided deafness.

    PubMed

    Rader, Tobias; Döge, Julia; Adel, Youssef; Weissgerber, Tobias; Baumann, Uwe

    2016-09-01

    In normal hearing, the pitch of an acoustic tone can theoretically be encoded by either the place of stimulation in the cochlea or the corresponding rate of vibration. Thus spectral attributes and temporal fine structure of an acoustic signal are naturally correlated. Cochlear implants (CIs), neural prosthetic devices that restore hearing in the profoundly hearing impaired, currently disregard this mechanism; electrical stimulation is provided at fixed electrode positions with default place independent stimulation rate assignments. This does not account for individual cochlear encoding depending on electrode array placement, variations in insertion depth, and the proximity to nerve fibers. Encoding pitch in such manner delivers limited tonal information. Consequently, music appraisal in CI users is often rated cacophonic while speech perception in quiet is close to normal in top performers. We hypothesize that this limitation in electric stimulation is at least partially due to the mismatch between frequency and place encoding in CIs. In the present study, we determined individual electrode locations by analysis of cochlear radiographic images obtained after surgery and calculated place dependent stimulation rates according to models of the normal tonotopic function. Pitch matching in CI users with single-sided deafness shows that place dependent stimulation rates allow thus far unparalleled restoration of tonotopic pitch perception. Collapsed data of matched pitch frequencies as a function of calculated electrical stimulation rate were well fitted by linear regression (R(2) = 0.878). Sound processing strategies incorporating place dependent stimulation rates are expected to improve pitch perception in CI users. PMID:27374479

  11. Scale-Dependent Rates of Uranyl Surface Complexation Reaction in Sediments

    SciTech Connect

    Liu, Chongxuan; Shang, Jianying; Kerisit, Sebastien N.; Zachara, John M.; Zhu, Weihuang

    2013-03-15

    Scale-dependency of uranyl[U(VI)] surface complexation rates was investigated in stirred flow-cell and column systems using a U(VI)-contaminated sediment from the US Department of Energy, Hanford site, WA. The experimental results were used to estimate the apparent rate of U(VI) surface complexation at the grain-scale and in porous media. Numerical simulations using molecular, pore-scale, and continuum models were performed to provide insights into and to estimate the rate constants of U(VI) surface complexation at the different scales. The results showed that the grain-scale rate constant of U(VI) surface complexation was over 3 to 10 orders of magnitude smaller, dependent on the temporal scale, than the rate constant calculated using the molecular simulations. The grain-scale rate was faster initially and slower with time, showing the temporal scale-dependency. The largest rate constant at the grain-scale decreased additional 2 orders of magnitude when the rate was scaled to the porous media in the column. The scaling effect from the grain-scale to the porous media became less important for the slower sorption sites. Pore-scale simulations revealed the importance of coupled mass transport and reactions in both intragranular and inter-granular domains, which caused both spatial and temporal dependence of U(VI) surface complexation rates in the sediment. Pore-scale simulations also revealed a new rate-limiting mechanism in the intragranular porous domains that the rate of coupled diffusion and surface complexation reaction was slower than either process alone. The results provided important implications for developing models to scale geochemical/biogeochemical reactions.

  12. Rapid evolutionary loss of metal resistance revealed by hatching decades-old eggs.

    PubMed

    Turko, Patrick; Sigg, Laura; Hollender, Juliane; Spaak, Piet

    2016-02-01

    We investigated the evolutionary response of an ecologically important freshwater crustacean, Daphnia, to a rapidly changing toxin environment. From the 1920s until the 1960s, the use of leaded gasoline caused the aquatic concentration of Pb to increase at least fivefold, presumably exerting rapid selective pressure on organisms for resistance. We predicted that Daphnia from this time of intense pollution would display greater resistance than those hatched from times of lower pollution. This question was addressed directly using the resurrection ecology approach, whereby dormant propagules from focal time periods were hatched and compared. We hatched several Daphnia genotypes from each of two Swiss lakes, during times of higher (1960s /1980s) and lower (2000s) lead stress, and compared their life histories under different laboratory levels of this stressor. Modern Daphnia had significantly reduced fitness, measured as the population growth rate (λ), when exposed to lead, whereas those genotypes hatched from times of high lead pollution did not display this reduction. These phenotypic differences contrast with only slight differences measured at neutral loci. We infer that Daphnia in these lakes were able to rapidly adapt to increasing lead concentrations, and just as rapidly lost this adaptation when the stressor was removed. PMID:26768308

  13. Temperature effects on hatching and viability of Juvenile Gill Lice, Salmincola californiensis.

    PubMed

    Vigil, E M; Christianson, K R; Lepak, J M; Williams, P J

    2016-07-01

    Salmonids of the genus Oncorhynchus, distributed throughout the Pacific Rim, can be infected by the gill lice species Salmincola californiensis (Dana, 1852), which makes them one of the most broadly distributed gill lice species. Despite their broad distribution and valuable obligate salmonid hosts, relatively little is known about S. californiensis. We evaluated effects of temperature on timing of S. californiensis hatching and survival of copepodids, and provide information on brood size and variability. Our results suggest that temperature was a primary driver of timing of S. californiensis hatching and post-hatching survival. Prior to this study, the free-swimming stage of S. californiensis was reported to survive approximately 2 days without a suitable host. We observed active copepodids 13 days after hatch with some individuals from most (>90%) viable egg sacs at all temperature treatments surviving ≥5 days. Our findings indicate that warmer temperatures could increase development rates of gill lice at certain life stages, potentially increasing fecundity. This information coupled with predictions that warmer water temperatures could intensify crowding of coldwater fishes, stress, and parasite transmission suggests that climate change could exacerbate negative effects of S. californiensis on ecologically and economically important salmonids. PMID:26538200

  14. No adverse effects were identified on the perinatal outcomes after laser-assisted hatching treatment.

    PubMed

    Zhou, Hanying; Zao, Wanqiu; Zhang, Wei; Shi, Juanzi; Shi, Wenhao

    2014-12-01

    The aim of this study was to evaluate the safety of laser-assisted hatching (LAH) by comparing obstetric and neonatal outcomes between assisted hatching and control groups in cryopreserved embryo transfer cycles. A retrospective cohort analysis was carried out. A total of 699 women with 392 infants delivered were included. Laser- assisted hatching was carried out on D-3 thawed and warmed embryos before transfer in 480 cryopreserved embryos transfer cycles. Obstetric outcomes, neonatal outcomes, and congenital birth defects were recorded. A total of 815 cryopreserved embryo transfer cycles (480 in LAH group and 335 in control group) in 699 patients were analysed. Statistically significantly higher implantation (31.85% versus 16.95%), clinical pregnancy (53.96% versus 33.43%) and live delivery (44.58% versus 23.88%) rates were observed in the LAH group (all P < 0.001). For either singleton or multiple gestations, no statistically significant differences were found in mean gestational age, mean birth weight and mean Apgar score. Four major malformations occurred in the assisted hatching group and three malformations (one major and two minor) in the control group. This study did not identify any harmful effect of LAH on neonates, which suggested that LAH may be a safe treatment in cryopreserved embryo transfer cycles. PMID:25444502

  15. Effects of Mycoplasma anatis and cold stress on hatching success and growth of mallard ducklings

    USGS Publications Warehouse

    Samuel, M.D.; Goldberg, D.R.; Thomas, C.B.; Sharp, P.

    1995-01-01

    We inoculated game-farm mallard (Anas platyrhynchos) eggs and 1-day-old birds with Mycoplasma anatis to determine its effect on hatching success and growth rates of ducklings. Inoculations of eggs reduced hatching success, hatchling size, and duckling growth rates, compared to controls. Intratracheal inoculations of 1-day-old birds did not affect growth rates. Hatchlings and 1-day-old ducklings grew much slower for the first 7 to 10 days when raised at 17 to 19 C, compared to controls raised at 30 to 35 C. The effect of cold stress on growth was greater than the effect of M. anatis infection; we found no synergistic effects between cold stress and M. anatis infection.

  16. Modeling of Rate-Dependent Hysteresis Using a GPO-Based Adaptive Filter.

    PubMed

    Zhang, Zhen; Ma, Yaopeng

    2016-01-01

    A novel generalized play operator-based (GPO-based) nonlinear adaptive filter is proposed to model rate-dependent hysteresis nonlinearity for smart actuators. In the proposed filter, the input signal vector consists of the output of a tapped delay line. GPOs with various thresholds are used to construct a nonlinear network and connected with the input signals. The output signal of the filter is composed of a linear combination of signals from the output of GPOs. The least-mean-square (LMS) algorithm is used to adjust the weights of the nonlinear filter. The modeling results of four adaptive filter methods are compared: GPO-based adaptive filter, Volterra filter, backlash filter and linear adaptive filter. Moreover, a phenomenological operator-based model, the rate-dependent generalized Prandtl-Ishlinskii (RDGPI) model, is compared to the proposed adaptive filter. The various rate-dependent modeling methods are applied to model the rate-dependent hysteresis of a giant magnetostrictive actuator (GMA). It is shown from the modeling results that the GPO-based adaptive filter can describe the rate-dependent hysteresis nonlinear of the GMA more accurately and effectively. PMID:26861349

  17. Modeling of Rate-Dependent Hysteresis Using a GPO-Based Adaptive Filter

    PubMed Central

    Zhang, Zhen; Ma, Yaopeng

    2016-01-01

    A novel generalized play operator-based (GPO-based) nonlinear adaptive filter is proposed to model rate-dependent hysteresis nonlinearity for smart actuators. In the proposed filter, the input signal vector consists of the output of a tapped delay line. GPOs with various thresholds are used to construct a nonlinear network and connected with the input signals. The output signal of the filter is composed of a linear combination of signals from the output of GPOs. The least-mean-square (LMS) algorithm is used to adjust the weights of the nonlinear filter. The modeling results of four adaptive filter methods are compared: GPO-based adaptive filter, Volterra filter, backlash filter and linear adaptive filter. Moreover, a phenomenological operator-based model, the rate-dependent generalized Prandtl-Ishlinskii (RDGPI) model, is compared to the proposed adaptive filter. The various rate-dependent modeling methods are applied to model the rate-dependent hysteresis of a giant magnetostrictive actuator (GMA). It is shown from the modeling results that the GPO-based adaptive filter can describe the rate-dependent hysteresis nonlinear of the GMA more accurately and effectively. PMID:26861349

  18. Role of the late sodium current in rate-dependent repolarization of the canine ventricle.

    PubMed

    Zhang, Hong; Yang, Lin; Yang, Zhao; Zheng, Xiao

    2013-12-31

    Late sodium current I(NaL) is an inward current participating in maintaining the plateau of the action potential. So far its role in the repolarization of canine hearts is not well known. In this paper, by taking advantage of a computer simulation method, we developed a one-dimensional transmural tissue to study the impacts of I(NaL) on rate-dependent repolarization and its ionic basis in the canine ventricle. An OpenMP parallel algorithm was performed on a four-core personal computer to accelerate the simulation. The results demonstrated that action potential durations of midmyocytes showed greater rate dependence than the endo- and epi-myocytes. When the pacing rate was reduced, repolarization of the tissue was prolonged while the transmural dispersion of repolarization (TDR) was enlarged. The enhancement of I(NaL) further amplified this rate-dependent repolarization and TDR meanwhile increased the risk of arrhythmogenesis. I(NaL) was found highly sensitive to the pacing rate by calculating its kinetics. The study suggested that I(NaL) played an important role in the rate-dependent repolarization of the canine ventricle. Selective blockade of I(NaL) could have clinical benefits, especially for such pathological conditions with enhanced I(NaL) as long QT 3 syndrome and heart failure. PMID:24495181

  19. Strain-rate-dependent model for the dynamic compression of elastoplastic spheres

    NASA Astrophysics Data System (ADS)

    Burgoyne, Hayden A.; Daraio, Chiara

    2014-03-01

    We present a force-displacement contact model for the compressive loading of elastoplastic spheres. This model builds from the well known Hertz contact law for elastic, quasistatic compression to incorporate a material's strain-rate-dependent plasticity in order to describe collisions between particles. In the quasistatic regime, finite-element analysis is used to derive an empirical function of the material properties. A Johnson-Cook strain rate dependence is then included into the model to study dynamic effects. We validate the model using split Hopkinson bar experiments and show that the model can accurately simulate the force-displacement response of strain-rate-dependent elastoplastic spheres during dynamic compression and unloading.

  20. Strain-rate-dependent model for the dynamic compression of elastoplastic spheres.

    PubMed

    Burgoyne, Hayden A; Daraio, Chiara

    2014-03-01

    We present a force-displacement contact model for the compressive loading of elastoplastic spheres. This model builds from the well known Hertz contact law for elastic, quasistatic compression to incorporate a material's strain-rate-dependent plasticity in order to describe collisions between particles. In the quasistatic regime, finite-element analysis is used to derive an empirical function of the material properties. A Johnson-Cook strain rate dependence is then included into the model to study dynamic effects. We validate the model using split Hopkinson bar experiments and show that the model can accurately simulate the force-displacement response of strain-rate-dependent elastoplastic spheres during dynamic compression and unloading. PMID:24730833

  1. CHARADE: A characteristic code for calculating rate-dependent shock-wave response

    SciTech Connect

    Johnson, J.N.; Tonks, D.L.

    1991-01-01

    In this report we apply spatially one-dimensional methods and simple shock-tracking techniques to the solution of rate-dependent material response under flat-plate-impact conditions. This method of solution eliminates potential confusion of material dissipation with artificial dissipative effects inherent in finite-difference codes, and thus lends itself to accurate calculation of elastic-plastic deformation, shock-to-detonation transition in solid explosives, and shock-induced structural phase transformation. Equations are presented for rate-dependent thermoelastic-plastic deformation for (100) planar shock-wave propagation in materials of cubic symmetry (or higher). Specific numerical calculations are presented for polycrystalline copper using the mechanical threshold stress model of Follansbee and Kocks with transition to dislocation drag. A listing of the CHARADE (for characteristic rate dependence) code and sample input deck are given. 26 refs., 11 figs.

  2. Implementation of Fiber Substructuring Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.

    2001-01-01

    A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were incorporated into a mechanics of materials based micromechanics method. In the current work, the micromechanics method is revised such that the composite unit cell is divided into a number of slices. Micromechanics equations are then developed for each slice, with laminate theory applied to determine the elastic properties, effective stresses and effective inelastic strains for the unit cell. Verification studies are conducted using two representative polymer matrix composites with a nonlinear, strain rate dependent deformation response. The computed results compare well to experimentally obtained values.

  3. Can-out hatch assembly with magnetic retention means

    DOEpatents

    Frank, Robert C.; Hoh, Joseph C.

    1986-01-01

    A can-out hatch assembly may be positioned in sealed engagement about an aperture within a chamber and is adapted to engage a cover on a container positioned over the aperture to allow the transfer of a contaminant from the chamber to the container while maintaining the contaminant as well as internal portions of the chamber and container isolated from the surrounding environment. With the container's cover engaged by the can-out hatch assembly, the hatch assembly as well as the cover may be pivotally displaced from the aperture with the cover maintaining the exterior portion of the hatch assembly isolated from the contaminant. After the contaminant is transferred from the chamber to the container, the hatch assembly and cover are again positioned in sealed engagement about the aperture. The hatch assembly then positions the cover upon the open end of the container in a sealed manner allowing the container to be removed while maintaining the chamber sealed relative to the surrounding environment. The can-out hatch assembly is particularly adapted for operation by remote control means within the sealed chamber.

  4. Can-out hatch assembly and positioning system

    DOEpatents

    Basnar, Paul J.; Frank, Robert C.; Hoh, Joseph C.

    1986-01-01

    A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction releases it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for threadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

  5. Can-out hatch assembly with magnetic retention means

    DOEpatents

    Frank, Robert C.; Hoh, Joseph C.

    1986-01-07

    A can-out hatch assembly may be positioned in sealed engagement about an aperture within a chamber and is adapted to engage a cover on a container positioned over the aperture to allow the transfer of a contaminant from the chamber to the container while maintaining the contaminant as well as internal portions of the chamber and container isolated from the surrounding environment. With the container's cover engaged by the can-out hatch assembly, the hatch assembly as well as the cover may be pivotally displaced from the aperture with the cover maintaining the exterior portion of the hatch assembly isolated from the contaminant. After the contaminant is transferred from the chamber to the container, the hatch assembly and cover are again positioned in sealed engagement about the aperture. The hatch assembly then positions the cover upon the open end of the container in a sealed manner allowing the container to be removed while maintaining the chamber sealed relative to the surrounding environment. The can-out hatch assembly is particularly adapted for operation by remote control means within the sealed chamber.

  6. Can-out hatch assembly with magnetic retention means

    DOEpatents

    Frank, R.C.; Hoh, J.C.

    1985-07-03

    A can-out hatch assembly may be positioned in sealed engagement about aperture within a chamber and is adapted to engage a cover on a container positioned over the aperture to allow the transfer of a contaminant from the chamber to the container while maintaining the contaminant as well as internal portions of the chamber and container isolated from the surrounding environment. With the container's cover engaged by the can-out hatch assembly, the hatch assembly as well as the cover may be pivotally displaced from the aperture with the cover maintaining the exterior portion of the hatch assembly isolated from the contaminant. After the contaminant is transferred from the chamber to the container, the hatch assembly and cover are again positioned in sealed engagement about the aperture. The hatch assembly then positions the cover upon the open end of the container in a sealed manner allowing the container to be removed while maintaining the chamber sealed relative to the surrounding environment. The can-out hatch assembly is particularly adapted for operation by remote control means within the sealed chamber.

  7. Can-out hatch assembly and positioning system

    DOEpatents

    Basnar, P.J.; Frank, R.C.; Hoh, J.C.

    1985-07-03

    A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction release it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for theadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

  8. Can-out hatch assembly and positioning system

    DOEpatents

    Basnar, Paul J.; Frank, Robert C.; Hoh, Joseph C.

    1986-01-07

    A can-out hatch assembly is adapted to engage in a sealed manner the upper end of a covered sealed container around an aperture in a sealed chamber and to remove the cover from the container permitting a contaminant to be transferred between the container and the chamber while isolating internal portions of the container and chamber from the surrounding environment. A swing bracket is coupled at a first end thereof to the inner, lower wall of the sealed container adjacent to the aperture therein. To a second end of the swing bracket is mounted a hatch cover which may be positioned in sealed engagement about the chamber's aperture by rotating the hatch cover in a first direction when the swing bracket is in the full down position. Rotation of the hatch cover in a second direction releases it from sealed engagement with the chamber's aperture. A lid support rod also coupled to the second end of the swing bracket and inserted through an aperture in the center of the hatch cover may be rotated for threadably engaging the container's cover whereupon the cover may be removed from the container and the hatch cover displaced from the aperture by pivoting displacement of the swing bracket. The contaminant may then be either removed from the container and placed within the sealed chamber, or vice versa, followed by positioning of the cover upon the container and the hatch cover over the aperture in a sealed manner.

  9. First size-dependent growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

    NASA Astrophysics Data System (ADS)

    Kuang, C.; Chen, M.; Zhao, J.; Smith, J.; McMurry, P. H.; Wang, J.

    2011-09-01

    This study presents the first measurements of size-dependent particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Data analysis methods were developed, de-coupling the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated particles were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the detector. Size and time-dependent growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, ranging, for example, from 5.6 ± 2.0 to 27 ± 5.3 nm h-1 in Boulder (13:00) and from 5.5 ± 0.82 to 7.6 ± 0.56 nm h-1 in Atlanta (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, having lower limit values that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and having upper limit values that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Survival probability calculations comparing constant and size-dependent growth indicate that neglecting the strong growth rate size dependence from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.

  10. Driving Rate Dependence of Avalanche Statistics and Shapes at the Yielding Transition.

    PubMed

    Liu, Chen; Ferrero, Ezequiel E; Puosi, Francesco; Barrat, Jean-Louis; Martens, Kirsten

    2016-02-12

    We study stress time series caused by plastic avalanches in athermally sheared disordered materials. Using particle-based simulations and a mesoscopic elastoplastic model, we analyze system size and shear-rate dependence of the stress-drop duration and size distributions together with their average temporal shape. We find critical exponents different from mean-field predictions, and a clear asymmetry for individual avalanches. We probe scaling relations for the rate dependency of the dynamics and we report a crossover towards mean-field results for strong driving. PMID:26918998

  11. Implementation of Higher Order Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Kim, Heung Soo; Zhu, Linfa; Chattopadhyay, Aditi; Goldberg, Robert K.

    2004-01-01

    A procedure has been developed to investigate the nonlinear response of composite plates under large strain and high strain rate loading. A recently developed strain dependent micromechanics model is extended to account for the shear effects during impact. Four different assumptions of shear deformation effects are investigated to improve the development strain rate dependent micromechanics model. A method to determine through the thickness strain and transverse Poisson's ratio is developed. The revised micromechanics model is implemented into higher order laminate theory. Parametric studies are conducted to investigate transverse shear effects during impact.

  12. Driving Rate Dependence of Avalanche Statistics and Shapes at the Yielding Transition

    NASA Astrophysics Data System (ADS)

    Liu, Chen; Ferrero, Ezequiel E.; Puosi, Francesco; Barrat, Jean-Louis; Martens, Kirsten

    2016-02-01

    We study stress time series caused by plastic avalanches in athermally sheared disordered materials. Using particle-based simulations and a mesoscopic elastoplastic model, we analyze system size and shear-rate dependence of the stress-drop duration and size distributions together with their average temporal shape. We find critical exponents different from mean-field predictions, and a clear asymmetry for individual avalanches. We probe scaling relations for the rate dependency of the dynamics and we report a crossover towards mean-field results for strong driving.

  13. Cryopreservation of European catfish Silurus glanis sperm: sperm motility, viability, and hatching success of embryos.

    PubMed

    Linhart, Otomar; Rodina, Marek; Flajshans, Martin; Gela, David; Kocour, Martin

    2005-12-01

    The aim of this study was to elaborate cryopreservation methods for ex situ conservation of European catfish. The success of sperm cryopreservation was evaluated by post-thaw sperm motility and velocity, percentage of live spermatozoa and fertility (hatching rates) using frozen/thawed sperm. The best hatching rates of 82-86% were obtained with sperm stored for 5 h before freezing in immobilizing solution and frozen with Me2SO in concentrations of 8, 10, and 12%, or with a mixture of 5% Me2SO and 5% propandiole. These results did not significantly differ from the fresh sperm control sample. The percentage of live spermatozoa in frozen/thawed sperm did not correlate with hatching rate or motility of spermatozoa, but was negatively correlated with velocity of spermatozoa (r=-0.47, P=0.05). The percentage motility in frozen/thawed sperm ranged from 8 to 62%, when sperm was stored in immobilizing solution 5h before freezing. The average value in the fresh sperm (control) was 96%. The frozen/thawed sperm motility rate significantly correlated with the hatching rate (r=0.76, P=0.0002), but not with the percentage of live spermatozoa (r=0.16, P=0.52) or the sperm velocity (r=0.07, P=0.79). The velocity of frozen/thawed spermatozoa ranged from 37 to 85 microm/s, whereby methanol concentrations of 7.5 and 10% resulted in highest velocities. Freezing sperm volumes of 1-4 ml did not affect the quality of frozen/thawed sperm. PMID:16122724

  14. A numerical basis for strain-gradient plasticity theory: Rate-independent and rate-dependent formulations

    NASA Astrophysics Data System (ADS)

    Nielsen, K. L.; Niordson, C. F.

    2014-02-01

    A numerical model formulation of the higher order flow theory (rate-independent) by Fleck and Willis [2009. A mathematical basis for strain-gradient plasticity theory - part II: tensorial plastic multiplier. Journal of the Mechanics and Physics of Solids 57, 1045-1057.], that allows for elastic-plastic loading/unloading and the interaction of multiple plastic zones, is proposed. The predicted model response is compared to the corresponding rate-dependent version of visco-plastic origin, and coinciding results are obtained in the limit of small strain-rate sensitivity. First, (i) the evolution of a single plastic zone is analyzed to illustrate the agreement with earlier published results, whereafter examples of (ii) multiple plastic zone interaction, and (iii) elastic-plastic loading/unloading are presented. Here, the simple shear problem of an infinite slab constrained between rigid plates is considered, and the effect of strain gradients, strain hardening and rate sensitivity is brought out. For clarity of results, a 1D model is constructed following a procedure suitable for generalization to 2D and 3D.

  15. Implications of a concentration-dependent growth rate on the boundary layer crystal-melt model

    NASA Astrophysics Data System (ADS)

    Lasaga, Antonio C.

    1981-12-01

    The influence of a melt boundary layer on crystal growth is analyzed. The treatment extends the results of Burton, Prim and Slichter (1953) and incorporates composition-dependent growth rates. It is shown that in these general cases the growth rate cannot be arbitrarily fixed but must satisfy a self-consistent equation. Self-consistency problems arise because the growth rate determines the composition profile in the melt and, in turn, the composition profile determines the growth rate. The self-consistent growth rate is shown to vary markedly with the ratio δ/D, where δ is the thickness of the boundary layer and D is the appropriate diffusion coefficient in the melt. This self-consistency can be very important in the analysis of both field and laboratory growth rates as well as in trace element partition kinetic models.

  16. Reasoning with base rates is routine, relatively effortless, and context dependent.

    PubMed

    Pennycook, Gordon; Thompson, Valerie A

    2012-06-01

    We tested models of base rate "neglect" using a novel paradigm. Participants (N = 62) judged the probability that a hypothetical person belonged to one of two categories (e.g., nurse/doctor) on the basis of either a personality description alone (NoBR) or the personality description and a base rate probability (BR). When base rates and descriptions were congruent, judgments in the BR condition were higher and more uniform than those in the NoBR condition. In contrast, base rates had a polarizing effect on judgments when they were incongruent with the descriptions, such that estimates were either consistent with the base rates or discrepant with them. These data suggest that the form of base rate use (i.e., whether base rates will be integrated with diagnostic information) is context dependent. In addition, judgments made under instructions to respond intuitively were influenced by the base rates and took the same length of time in the two conditions. These data suggest that the use of base rates is routine and effortless and that base rate "neglect" is really a mixture of two strategies, one that is informed primarily by the base rate and the other by the personality description. PMID:22427266

  17. Does the Rate of Collisionless Magnetic Reconnection Depend on the Dissipation Mechanism?

    NASA Technical Reports Server (NTRS)

    Aunai, Nicolas; Hesse, Michael; Black, Carrie; Evans, Rebekah; Kuznetsova, Maria

    2012-01-01

    The importance of the electron dissipation effect on the reconnection rate is investigated in the general case of asymmetric collisionless magnetic reconnection. Contrary to the standard collisionless reconnection model, it is found that the reconnection rate, and the macroscopic evolution of the reconnecting system, crucially depend on the nature of the dissipation mechanism and that the Hall effect alone is not able to sustain fast reconnection.

  18. Cryobiological properties of immature zebrafish oocytes assessed by their ability to be fertilized and develop into hatching embryos.

    PubMed

    Seki, Shinsuke; Kouya, Toshimitsu; Tsuchiya, Ryoma; Valdez, Delgado M; Jin, Bo; Koshimoto, Chihiro; Kasai, Magosaburo; Edashige, Keisuke

    2011-02-01

    As a step to develop a cryopreservation method for zebrafish oocytes, we investigated the cryobiological properties of immature oocytes at stage III by examining their ability to mature and to develop into hatching embryos after fertilization. When oocytes were chilled at -5°C for 30min, the maturation rate decreased, but the rates of fertilization and hatching were not significantly different from those of controls. When oocytes were exposed to hypotonic solutions for 60min at 25°C, the rates of maturation, fertilization, and hatching decreased in a solution with 0.16Osm/kg or below. When oocytes were exposed to hypertonic solutions (containing sucrose) at 25°C for 30min, the maturation rate decreased in solution with 0.51Osm/kg, whereas the hatching rate decreased with lower osmolality (0.40Osm/kg). In an experiment on the toxicity of cryoprotectants (∼10%, at 25°C), it was found that glycerol and ethylene glycol were toxic both by the assessment of maturation and hatching. Propylene glycol, DMSO and methanol were less toxic by the assessment of maturation, but were found to be toxic by the assessment of hatching. Methanol was the least toxic, but it was less effective to make a solution vitrify than propylene glycol. Therefore, a portion of methanol was replaced with propylene glycol. The replacement increased the toxicity, but could be effective to reduce chilling injury at -5°C. These results clarified the sensitivity of immature oocytes to various cryobiological properties accurately, which will be useful for realizing cryopreservation of zebrafish oocytes. PMID:21114971

  19. Mapping Strain-rate Dependent Dislocation-Defect Interactions by Atomistic Simulations

    SciTech Connect

    Fan, Yue; Osetskiy, Yury N; Yip, Sidney; Yildiz-Botterud, Bilge

    2013-01-01

    Probing the mechanisms of defect-defect interactions at strain rates lower than 106 s-1 is an unresolved challenge to date to molecular dynamics (MD) techniques. Here we propose a novel atomistic approach based on transition state theory and the concept of a strain-dependent effective activation barrier that is capable of simulating the kinetics of dislocation-defect interactions at virtually any strain rate, exemplified within 10-7 to 107 s-1. We apply this approach to the problem of an edge dislocation colliding with a cluster of self-interstitial atoms (SIA) under shear deformation. Using an activation-relaxation algorithm (1), we uncover a unique strain-rate dependent trigger mechanism that allows the SIA cluster to be absorbed during the process leading to dislocation climb. Guided by this finding, we determine the activation barrier of the trigger mechanism as a function of shear strain, and use that in a coarse-graining rate equation formulation for constructing a mechanism map in the phase space of strain-rate and temperature. Our predictions of a crossover from a defect recovery at the low strain rate regime to defect absorption behavior in the high strain-rate regime are validated against our own independent, direct MD simulations at 105 to 107 s-1. Implications of the present approach for probing molecular-level mechanisms in strain-rate regimes previously considered inaccessible to atomistic simulations are discussed.

  20. Size dependence of the multiple exciton generation rate in CdSe quantum dots.

    PubMed

    Lin, Zhibin; Franceschetti, Alberto; Lusk, Mark T

    2011-04-26

    The multiplication rates of hot carriers in CdSe quantum dots are quantified using an atomistic pseudopotential approach and first-order perturbation theory. We consider both the case of an individual carrier (electron or hole) decaying into a trion and the case of an electron-hole pair decaying into a biexciton. The dependence on quantum dot volume of multiplication rate, density of final states, and effective Coulomb interaction are determined. We show that the multiplication rate of a photogenerated electron-hole pair decreases with dot size for a given absolute photon energy. However, if the photon energy is rescaled by the volume-dependent optical gap, then smaller dots exhibit an enhancement in carrier multiplication rate for a given relative photon energy. We find that holes have much higher multiplication rates than electrons of the same excess energy due to the larger density of final states (positive trions). When electron-hole pairs are generated by photon absorption, however, the net carrier multiplication rate is dominated by electrons because they have much higher excess energy on average. We also find, contrary to earlier studies, that the effective Coulomb coupling governing carrier multiplication is energy-dependent. PMID:21355556

  1. Geological dates and molecular rates: fish DNA sheds light on time dependency.

    PubMed

    Burridge, Christopher P; Craw, Dave; Fletcher, David; Waters, Jonathan M

    2008-04-01

    Knowledge of DNA evolution is central to our understanding of biological history, but how fast does DNA change? Previously, pedigree and ancient DNA studies--focusing on evolution in the short term--have yielded molecular rate estimates substantially faster than those based on deeper phylogenies. It has recently been suggested that short-term, elevated molecular rates decay exponentially over 1-2 Myr to long-term, phylogenetic rates, termed "time dependency of molecular rates." This transition has potential to confound molecular inferences of demographic parameters and dating of many important evolutionary events. Here, we employ a novel approach--geologically dated changes in river drainages and isolation of fish populations--to document rates of mitochondrial DNA change over a range of temporal scales. This method utilizes precise spatiotemporal disruptions of linear freshwater systems and hence avoids many of the limitations associated with typical DNA calibration methods involving fossil data or island formation. Studies of freshwater-limited fishes across the South Island of New Zealand have revealed that genetic relationships reflect past, rather than present, drainage connections. Here, we use this link between drainage geology and genetics to calibrate rates of molecular evolution across nine events ranging in age from 0.007 Myr (Holocene) to 5.0 Myr (Pliocene). Molecular rates of change in galaxiid fishes from calibration points younger than 200 kyr were faster than those based on older calibration points. This study provides conclusive evidence of time dependency in molecular rates as it is based on a robust calibration system that was applied to closely related taxa, and analyzed using a consistent and rigorous methodology. The time dependency observed here appears short-lived relative to previous suggestions (1-2 Myr), which has bearing on the accuracy of molecular inferences drawn from processes operating within the Quaternary and mechanisms invoked to

  2. The vibrational dependence of dissociative recombination: Rate constants for N{sub 2}{sup +}

    SciTech Connect

    Guberman, Steven L.

    2014-11-28

    Dissociative recombination rate constants are reported with electron temperature dependent uncertainties for the lowest 5 vibrational levels of the N{sub 2}{sup +} ground state. The rate constants are determined from ab initio calculations of potential curves, electronic widths, quantum defects, and cross sections. At 100 K electron temperature, the rate constants overlap with the exception of the third vibrational level. At and above 300 K, the rate constants for excited vibrational levels are significantly smaller than that for the ground level. It is shown that any experimentally determined total rate constant at 300 K electron temperature that is smaller than 2.0 × 10{sup −7} cm{sup 3}/s is likely to be for ions that have a substantially excited vibrational population. Using the vibrational level specific rate constants, the total rate constant is in very good agreement with that for an excited vibrational distribution found in a storage ring experiment. It is also shown that a prior analysis of a laser induced fluorescence experiment is quantitatively flawed due to the need to account for reactions with unknown rate constants. Two prior calculations of the dissociative recombination rate constant are shown to be inconsistent with the cross sections upon which they are based. The rate constants calculated here contribute to the resolution of a 30 year old disagreement between modeled and observed N{sub 2}{sup +} ionospheric densities.

  3. Category Rating Is Based on Prototypes and Not Instances: Evidence from Feedback-Dependent Context Effects

    ERIC Educational Resources Information Center

    Petrov, Alexander A.

    2011-01-01

    Context effects in category rating on a 7-point scale are shown to reverse direction depending on feedback. Context (skewed stimulus frequencies) was manipulated between and feedback within subjects in two experiments. The diverging predictions of prototype- and exemplar-based scaling theories were tested using two representative models: ANCHOR…

  4. Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films.

    PubMed

    Glor, Ethan C; Fakhraai, Zahra

    2016-01-01

    This report aims to fully describe the experimental technique of using ellipsometry for cooling rate dependent Tg (CR-Tg) experiments. These measurements are simple high-throughput characterization experiments, which can determine the glass transition temperature (Tg), average dynamics, fragility and the expansion coefficient of the super-cooled liquid and glassy states for a variety of glassy materials. This technique allows for these parameters to be measured in a single experiment, while other methods must combine a variety of different techniques to investigate all of these properties. Measurements of dynamics close to Tg are particularly challenging. The advantage of cooling rate dependent Tg measurements over other methods which directly probe bulk and surface relaxation dynamics is that they are relatively quick and simple experiments, which do not utilize fluorophores or other complicated experimental techniques. Furthermore, this technique probes the average dynamics of technologically relevant thin films in temperature and relaxation time (τα) regimes relevant to the glass transition (τα > 100 sec). The limitation to using ellipsometry for cooling rate dependent Tg experiments is that it cannot probe relaxation times relevant to measurements of viscosity (τα < 1 sec). Other cooling rate dependent Tg measurement techniques, however, can extend the CR-Tg method to faster relaxation times. Furthermore, this technique can be used for any glassy system so long as the integrity of the film remains throughout the experiment. PMID:26863256

  5. Time dependent parallel viscosity and relaxation rate of poloidal rotation in the banana regime

    SciTech Connect

    Hsu, C.T.; Shaing, K.C.; Gormley, R. )

    1994-01-01

    Time dependent ion parallel viscous force in the banana regime with arbitrary inverse aspect ratio [epsilon] is calculated using the eigenfunction approach. The flux surface averaged viscosity is then used to study the relaxation process of the poloidal rotation which leads to oscillatory relaxation behavior. The relaxation rate [nu][sub [ital p

  6. Direct Behavior Rating (DBR): Generalizability and Dependability across Raters and Observations

    ERIC Educational Resources Information Center

    Christ, Theodore J.; Riley-Tillman, T. Chris; Chafouleas, Sandra M.; Boice, Christina H.

    2010-01-01

    Generalizability theory was used to examine the generalizability and dependability of outcomes from two single-item Direct Behavior Rating (DBR) scales: DBR of actively manipulating and DBR of visually distracted. DBR is a behavioral assessment tool with specific instrumentation and procedures that can be used by a variety of service delivery…

  7. Exact results on the temperature dependence of the specific equilibrium recombination rate coefficient

    NASA Technical Reports Server (NTRS)

    Mickens, R. E.

    1978-01-01

    Two theorems based on Laplace transforms are used to relate threshold and high energy behavior to a temperature dependent variable. A recombination reaction involving electrically neutral species is presented to illustrate the dynamics of the activation energy and the associated rate coefficient. The distribution functions are shown to correspond with those predicted by Boltzmann's equations.

  8. Translation elicits a growth rate-dependent, genome-wide, differential protein production in Bacillus subtilis.

    PubMed

    Borkowski, Olivier; Goelzer, Anne; Schaffer, Marc; Calabre, Magali; Mäder, Ulrike; Aymerich, Stéphane; Jules, Matthieu; Fromion, Vincent

    2016-01-01

    Complex regulatory programs control cell adaptation to environmental changes by setting condition-specific proteomes. In balanced growth, bacterial protein abundances depend on the dilution rate, transcript abundances and transcript-specific translation efficiencies. We revisited the current theory claiming the invariance of bacterial translation efficiency. By integrating genome-wide transcriptome datasets and datasets from a library of synthetic gfp-reporter fusions, we demonstrated that translation efficiencies in Bacillus subtilis decreased up to fourfold from slow to fast growth. The translation initiation regions elicited a growth rate-dependent, differential production of proteins without regulators, hence revealing a unique, hard-coded, growth rate-dependent mode of regulation. We combined model-based data analyses of transcript and protein abundances genome-wide and revealed that this global regulation is extensively used in B. subtilis We eventually developed a knowledge-based, three-step translation initiation model, experimentally challenged the model predictions and proposed that a growth rate-dependent drop in free ribosome abundance accounted for the differential protein production. PMID:27193784

  9. Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors

    SciTech Connect

    Karsch, L.; Beyreuther, E.; Burris-Mog, T.; Kraft, S.; Richter, C.; Zeil, K.; Pawelke, J.

    2012-05-15

    Purpose: The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10{sup 11} Gy/s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. Methods: The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the number of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. Results: The dosimeters are dose rate independent up to 410{sup 9} Gy/s within 2% (OSL and TLD) and up to 1510{sup 9} Gy/s within 5% (EBT films). The diamond detectors show strong dose rate dependence. Conclusions: TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.

  10. Mapping strain rate dependence of dislocation-defect interactions by atomistic simulations

    PubMed Central

    Fan, Yue; Osetskiy, Yuri N.; Yip, Sidney; Yildiz, Bilge

    2013-01-01

    Probing the mechanisms of defect–defect interactions at strain rates lower than 106 s−1 is an unresolved challenge to date to molecular dynamics (MD) techniques. Here we propose an original atomistic approach based on transition state theory and the concept of a strain-dependent effective activation barrier that is capable of simulating the kinetics of dislocation–defect interactions at virtually any strain rate, exemplified within 10−7 to 107 s−1. We apply this approach to the problem of an edge dislocation colliding with a cluster of self-interstitial atoms (SIAs) under shear deformation. Using an activation–relaxation algorithm [Kushima A, et al. (2009) J Chem Phys 130:224504], we uncover a unique strain-rate–dependent trigger mechanism that allows the SIA cluster to be absorbed during the process, leading to dislocation climb. Guided by this finding, we determine the activation barrier of the trigger mechanism as a function of shear strain, and use that in a coarse-graining rate equation formulation for constructing a mechanism map in the phase space of strain rate and temperature. Our predictions of a crossover from a defect recovery at the low strain-rate regime to defect absorption behavior in the high strain-rate regime are validated against our own independent, direct MD simulations at 105 to 107 s−1. Implications of the present approach for probing molecular-level mechanisms in strain-rate regimes previously considered inaccessible to atomistic simulations are discussed. PMID:24114271

  11. A study of angular dependence in the ablation rate of polymers by nanosecond pulses

    NASA Astrophysics Data System (ADS)

    Pedder, James E. A.; Holmes, Andrew S.

    2006-02-01

    Measurements of ablation rate have traditionally been carried out only at normal incidence. However, in real-world applications ablation is often carried out at oblique angles, and it is useful to have prior knowledge of the ablation rate in this case. Detailed information about the angular dependence is also important for the development of ablation simulation tools, and can provide additional insight into the ablation mechanism. Previously we have reported on the angular dependence of direct-write ablation at 266 nm wavelength in solgel and polymer materials. In this paper we present a systematic study of angular dependence for excimer laser ablation of two polymer materials of interest for microfabrication: polycarbonate and SU8 photoresist. The results are used to improve simulation models to aid in mask design.

  12. Nonlinear modeling on rate dependent ferroelectric and ferroelastic response of 1-3 piezocomposites

    NASA Astrophysics Data System (ADS)

    Jayendiran, R.; Arockiarajan, A.

    2016-06-01

    The effect of loading rate on ferroelectric and ferroelastic behavior of 1-3 piezocomposites is presented in this work. Experiments are conducted for various loading rates under different loading conditions such as electrical and electromechanical to measure the rate dependent response of 1-3 piezocomposite compared with bulk piezoceramics. A thermodynamic based rate dependent domain switching criteria has been proposed to predict the ferroelectric and ferroelastic behavior of homogenized 1-3 piezocomposites. In this model, volume fraction of six distinct uni-axial variants are used as internal variables to describe the microscopic state of the material. Plasticity based kinematic hardening parameter is introduced as a function of internal variables to describe the grain boundary effects. Homogenization of 1-3 piezocomposite material properties are obtained by finite element (FE) resonator models using commercially available FE tool Abaqus. To evaluate the possible modes of vibration of 1-3 piezocomposite four different configuration of FE resonators are modeled. The FE resonator model is validated with the impedance spectra obtained experimentally for length extensional and thickness extensional resonator models. The predicted effective properties using the resonance based technique are incorporated in the proposed rate dependent macromechanical model to study the behavior of 1-3 piezocomposites. The simulated results are compared with the experimental observations.

  13. 46 CFR 78.17-35 - Hatches and other openings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... (4) On ocean, coastwise, or Great Lakes vessels of 150 gross tons and over, all opening type port... master at his discretion does not secure the hatches, a notation of this fact shall be made in...

  14. 46 CFR 78.17-35 - Hatches and other openings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... (4) On ocean, coastwise, or Great Lakes vessels of 150 gross tons and over, all opening type port... master at his discretion does not secure the hatches, a notation of this fact shall be made in...

  15. 10. VIEW OF SILO DOORS, AIR VENTS, AND ESCAPE HATCH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. VIEW OF SILO DOORS, AIR VENTS, AND ESCAPE HATCH, LOOKING EAST. WHITE STRUCTURES BELONG TO CURRENT OCCUPANTS Everett Weinreb, photographer, April 1988 - Los Pinetos Nike Missile Site, Santa Clara Road, Los Angeles National Forest, Sylmar, Los Angeles County, CA

  16. Edwin I. Hatch nuclear plant implementation of improved technical specifications

    SciTech Connect

    Mahler, S.R.; Pendry, D.

    1994-12-31

    Edwin I. Hatch nuclear plant consists of two General Electric boiling water reactor/4 units, with a common control room and a common refueling floor. In March 1993, Hatch began conversion of both units` technical specifications utilizing NUREG 1433. The technical specifications amendment request was submitted February 25, 1994. Issuance is scheduled for October 21, 1994, with implementation on March 15, 1994. The current unit-1 technical specifications are in the {open_quotes}custom{close_quotes} format, and the unit-2 technical specifications are in the old standard format. Hatch previously relocated the fire protection and radiological technical specifications requirements. The Hatch conversion will provide consistency between the two units, to the extent practicable.

  17. 8. INTERIOR VIEW OF STATION PARLEY LOOKING THROUGH THE HATCH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. INTERIOR VIEW OF STATION PARLEY LOOKING THROUGH THE HATCH, SHOWING THE FLOOR AND THE INSTRUMENT PEDESTAL WITH HARDWARE. - White's Point Reservation, Base End Stations, B"6, Bounded by Voyager Circle & Mariner Drive, San Pedro, Los Angeles County, CA

  18. 9. Mispillion Lighthouse, Tower Lantern Floor Hatch Mispillion Lighthouse, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. Mispillion Lighthouse, Tower Lantern Floor Hatch - Mispillion Lighthouse, South bank of Mispillion River at its confluence with Delaware River at northeast end of County Road 203, 7 miles east of Milford, Milford, Sussex County, DE

  19. Astronaut Richard Gordon returns to hatch of spacecraft following EVA

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Astronaut Richard F. Gordon Jr., pilot for the Gemini 11 space flight, returns to the hatch of the spacecraft following extravehicular activity (EVA). This picture was taken over the Atlantic Ocean at approximately 160 nautical miles above the earth's surface.

  20. 14. View inside Building 802, the "Escape Hatch" at the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. View inside Building 802, the "Escape Hatch" at the rear of the "Sleeping Quarters", facing south. - Naval Air Station Fallon, 100-man Fallout Shelter, 800 Complex, off Carson Road near intersection of Pasture & Berney Roads, Fallon, Churchill County, NV

  1. 61. View of exhaust air vent (foreground), escape hatch, and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. View of exhaust air vent (foreground), escape hatch, and elevator doors at launch pad "A" with building 157, sentry control box on right, looking southwest - Nike Missile Battery MS-40, County Road No. 260, Farmington, Dakota County, MN

  2. 52. Patent steering gear, hatch and steering compass binnacle, view ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. Patent steering gear, hatch and steering compass binnacle, view from starboard looking aft. Photograph by Jet Lowe, April 1988. - Ship BALCLUTHA, 2905 Hyde Street Pier, San Francisco, San Francisco County, CA

  3. Interior below decks in fish hold looking forward. Fish hatch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior below decks in fish hold looking forward. Fish hatch opening is at upper left, ceiling planks and knees at center and right. - Purse Seiner SHENANDOAH, Gig Harbor Peninsula Historical Society and Museum, Gig Harbor, Pierce County, WA

  4. Simulation of biochemical reactions with time-dependent rates by the rejection-based algorithm

    SciTech Connect

    Thanh, Vo Hong; Priami, Corrado

    2015-08-07

    We address the problem of simulating biochemical reaction networks with time-dependent rates and propose a new algorithm based on our rejection-based stochastic simulation algorithm (RSSA) [Thanh et al., J. Chem. Phys. 141(13), 134116 (2014)]. The computation for selecting next reaction firings by our time-dependent RSSA (tRSSA) is computationally efficient. Furthermore, the generated trajectory is exact by exploiting the rejection-based mechanism. We benchmark tRSSA on different biological systems with varying forms of reaction rates to demonstrate its applicability and efficiency. We reveal that for nontrivial cases, the selection of reaction firings in existing algorithms introduces approximations because the integration of reaction rates is very computationally demanding and simplifying assumptions are introduced. The selection of the next reaction firing by our approach is easier while preserving the exactness.

  5. Implementation of Laminate Theory Into Strain Rate Dependent Micromechanics Analysis of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.

    2000-01-01

    A research program is in progress to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to impact loads. Previously, strain rate dependent inelastic constitutive equations developed to model the polymer matrix were implemented into a mechanics of materials based micromechanics method. In the current work, the computation of the effective inelastic strain in the micromechanics model was modified to fully incorporate the Poisson effect. The micromechanics equations were also combined with classical laminate theory to enable the analysis of symmetric multilayered laminates subject to in-plane loading. A quasi-incremental trapezoidal integration method was implemented to integrate the constitutive equations within the laminate theory. Verification studies were conducted using an AS4/PEEK composite using a variety of laminate configurations and strain rates. The predicted results compared well with experimentally obtained values.

  6. Size-dependent standard deviation for growth rates: empirical results and theoretical modeling.

    PubMed

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H Eugene; Grosse, I

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation sigma(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation sigma(R) on the average value of the wages with a scaling exponent beta approximately 0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation sigma(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of sigma(R) on the average payroll with a scaling exponent beta approximately -0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable. PMID:18643131

  7. Size-dependent standard deviation for growth rates: Empirical results and theoretical modeling

    NASA Astrophysics Data System (ADS)

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H. Eugene; Grosse, I.

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation σ(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation σ(R) on the average value of the wages with a scaling exponent β≈0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation σ(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of σ(R) on the average payroll with a scaling exponent β≈-0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

  8. DETAIL OF OPEN HATCH SHOWING INTERIOR OF MISSILE TUBE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF OPEN HATCH SHOWING INTERIOR OF MISSILE TUBE AND OPEN HATCH AND DOOR ON OPPOSITE SIDE OF TUBE (AT THIRD LEVEL OF MISSILE LAB). VIEW FACING WEST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

  9. Does lighting manipulation during incubation affect hatching rhythms and early development of sole?

    PubMed

    Blanco-Vives, B; Aliaga-Guerrero, M; Cañavate, J P; Muñoz-Cueto, J A; Sánchez-Vázquez, F J

    2011-05-01

    Light plays a key role in the development of biological rhythms in fish. Previous research on Senegal sole has revealed that both spawning rhythms and larval development are strongly influenced by lighting conditions. However, hatching rhythms and the effect of light during incubation are as yet unexplored. Therefore, the aim of this study was to investigate the impact of the light spectrum and photoperiod on Solea senegalensis eggs and larvae until day 7 post hatching (dph). To this end, eggs were collected immediately after spawning during the night and exposed to continuous light (LL), continuous darkness (DD), or light-dark (LD) 12L:12D cycles of white light (LD(W)), blue light (LD(B); λ(peak) = 463 nm), or red light (LD(R); λ(peak) = 685 nm). Eggs exposed to LD(B) had the highest hatching rate (94.5% ± 1.9%), whereas LD(R) and DD showed the lowest hatching rate (54.4% ± 3.9% and 48.4% ± 4.2%, respectively). Under LD conditions, the hatching rhythm peaked by the end of the dark phase, but was advanced in LD(B) (zeitgeber time 8 [ZT8]; ZT0 representing the onset of darkness) in relation to LD(W) and LD(R) (ZT11). Under DD conditions, the same rhythm persisted, although with lower amplitude, whereas under LL the hatching rhythm split into two peaks (ZT8 and ZT13). From dph 4 onwards, larvae under LD(B) showed the best growth and quickest development (advanced eye pigmentation, mouth opening, and pectoral fins), whereas larvae under LD(R) and DD had the poorest performance. These results reveal that developmental rhythms at the egg stage are tightly controlled by light characteristics, underlining the importance of reproducing their natural underwater photoenvironment (LD cycles of blue wavelengths) during incubation and early larvae development of fish. PMID:21539421

  10. Rate Constant and Temperature Dependence for the Reaction of Hydroxyl Radicals with 2-Flouropropane (FC-281ea) and Comparison with an Estimated Rate Constant

    NASA Technical Reports Server (NTRS)

    DeMore, W.; Wilson, E., Jr.

    1998-01-01

    Relative rate experiments were used to measure the rate constant and temperature dependence of the reaction of OH radicals with 2-fluoropropane (HFC-281ea), using ethane, propane, ethyl chloride as reference standards.

  11. Viscosity Dependence of Some Protein and Enzyme Reaction Rates: Seventy-Five Years after Kramers.

    PubMed

    Sashi, Pulikallu; Bhuyan, Abani K

    2015-07-28

    Kramers rate theory is a milestone in chemical reaction research, but concerns regarding the basic understanding of condensed phase reaction rates of large molecules in viscous milieu persist. Experimental studies of Kramers theory rely on scaling reaction rates with inverse solvent viscosity, which is often equated with the bulk friction coefficient based on simple hydrodynamic relations. Apart from the difficulty of abstraction of the prefactor details from experimental data, it is not clear why the linearity of rate versus inverse viscosity, k ∝ η(-1), deviates widely for many reactions studied. In most cases, the deviation simulates a power law k ∝ η(-n), where the exponent n assumes fractional values. In rate-viscosity studies presented here, results for two reactions, unfolding of cytochrome c and cysteine protease activity of human ribosomal protein S4, show an exceedingly overdamped rate over a wide viscosity range, registering n values up to 2.4. Although the origin of this extraordinary reaction friction is not known at present, the results indicate that the viscosity exponent need not be bound by the 0-1 limit as generally suggested. For the third reaction studied here, thermal dissociation of CO from nativelike cytochrome c, the rate-viscosity behavior can be explained using Grote-Hynes theory of time-dependent friction in conjunction with correlated motions intrinsic to the protein. Analysis of the glycerol viscosity-dependent rate for the CO dissociation reaction in the presence of urea as the second variable shows that the protein stabilizing effect of subdenaturing amounts of urea is not affected by the bulk viscosity. It appears that a myriad of factors as diverse as parameter uncertainty due to the difficulty of knowing the exact reaction friction and both mode and consequences of protein-solvent interaction work in a complex manner to convey as though Kramers rate equation is not absolute. PMID:26135219

  12. The effects of temperature change on the hatching success and larval survival of largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu.

    PubMed

    Landsman, S J; Gingerich, A J; Philipp, D P; Suski, C D

    2011-04-01

    In this study, the effects of abrupt temperature change on the hatching success and larval survival of eggs, yolk-sac larvae (YSL) and larvae above nest (LAN), for both largemouth bass Micropterus salmoides and smallmouth bass Micropterus dolomieu were quantified. Temperature had a significant effect on hatching success and time to 50% mortality, with large heat shocks causing accelerated mortality. The temperature changes shown to influence survival of all life stages, however, were beyond what is typically experienced in the wild. Micropterus salmoides had greater egg hatching success rates and increased survival rates at YSL and LAN stages, relative to M. dolomieu. Additionally, egg hatching success and survival of LAN varied across nests within the study. These findings suggest that temperature alone may not account for variations in year-class strength and may emphasize the need for protection of the nest-guarding male Micropterus spp. to ensure recruitment. PMID:21463315

  13. Density-Dependent Demographic Variation Determines Extinction Rate of Experimental Populations

    PubMed Central

    2005-01-01

    Understanding population extinctions is a chief goal of ecological theory. While stochastic theories of population growth are commonly used to forecast extinction, models used for prediction have not been adequately tested with experimental data. In a previously published experiment, variation in available food was experimentally manipulated in 281 laboratory populations of Daphnia magna to test hypothesized effects of environmental variation on population persistence. Here, half of those data were used to select and fit a stochastic model of population growth to predict extinctions of populations in the other half. When density-dependent demographic stochasticity was detected and incorporated in simple stochastic models, rates of population extinction were accurately predicted or only slightly biased. However, when density-dependent demographic stochasticity was not accounted for, as is usual when forecasting extinction of threatened and endangered species, predicted extinction rates were severely biased. Thus, an experimental demonstration shows that reliable estimates of extinction risk may be obtained for populations in variable environments if high-quality data are available for model selection and if density-dependent demographic stochasticity is accounted for. These results suggest that further consideration of density-dependent demographic stochasticity is required if predicted extinction rates are to be relied upon for conservation planning. PMID:15934788

  14. Finite Element Analysis of the Time-Dependent Smoluchowski Equation for Acetylcholinesterase Reaction Rate Calculations

    PubMed Central

    Cheng, Yuhui; Suen, Jason K.; Zhang, Deqiang; Bond, Stephen D.; Zhang, Yongjie; Song, Yuhua; Baker, Nathan A.; Bajaj, Chandrajit L.; Holst, Michael J.; McCammon, J. Andrew

    2007-01-01

    This article describes the numerical solution of the time-dependent Smoluchowski equation to study diffusion in biomolecular systems. Specifically, finite element methods have been developed to calculate ligand binding rate constants for large biomolecules. The resulting software has been validated and applied to the mouse acetylcholinesterase (mAChE) monomer and several tetramers. Rates for inhibitor binding to mAChE were calculated at various ionic strengths with several different time steps. Calculated rates show very good agreement with experimental and theoretical steady-state studies. Furthermore, these finite element methods require significantly fewer computational resources than existing particle-based Brownian dynamics methods and are robust for complicated geometries. The key finding of biological importance is that the rate accelerations of the monomeric and tetrameric mAChE that result from electrostatic steering are preserved under the non-steady-state conditions that are expected to occur in physiological circumstances. PMID:17307827

  15. A numerical investigation of oxygen concentration dependence on biodegradation rate laws in vapor intrusion

    PubMed Central

    Yao, Yijun; Shen, Rui; Pennel, Kelly G.; Suuberg, Eric M.

    2013-01-01

    In subsurface vapor intrusion, aerobic biodegradation has been considered as a major environmental factor that determines the soil gas concentration attenuation factors for contaminants such as petroleum hydrocarbons. The site investigation showed that oxygen could play an important role in this biodegradation rate, and this paper explores the influence of oxygen concentration in biodegradation reactions included in vapor intrusion (VI) models. Two different three dimensional (3-D) numerical models of vapor intrusion were explored for their sensitivity to the form of the biodegradation rate law. A second order biodegradation rate law, explicitly including oxygen concentration dependence, was introduced into one model. The results indicate that the aerobic/anoxic interface depth is determined by the ratio of contaminant source vapor to atmospheric oxygen concentration, and that the contaminant concentration profile in the aerobic zone was significantly influenced by the choice of rate law. PMID:24197079

  16. A numerical investigation of oxygen concentration dependence on biodegradation rate laws in vapor intrusion.

    PubMed

    Yao, Yijun; Shen, Rui; Pennel, Kelly G; Suuberg, Eric M

    2013-12-01

    In subsurface vapor intrusion, aerobic biodegradation has been considered as a major environmental factor that determines the soil gas concentration attenuation factors for contaminants such as petroleum hydrocarbons. The site investigation has shown that oxygen can play an important role in this biodegradation rate, and this paper explores the influence of oxygen concentration on biodegradation reactions included in vapor intrusion (VI) models. Two different three dimensional (3-D) numerical models of vapor intrusion were explored for their sensitivity to the form of the biodegradation rate law. A second order biodegradation rate law, explicitly including oxygen concentration dependence, was introduced into one model. The results indicate that the aerobic/anoxic interface depth is determined by the ratio of contaminant source vapor to atmospheric oxygen concentration, and that the contaminant concentration profile in the aerobic zone was significantly influenced by the choice of rate law. PMID:24197079

  17. Sleep Stage Dependence of Invariance Characteristics in Fluctuations of Healthy Human Heart Rate

    NASA Astrophysics Data System (ADS)

    Togo, Fumiharu; Kiyono, Ken; Struzik, Zbigniew R.; Yamamoto, Yoshiharu

    2005-08-01

    The outstanding feature of healthy human heart rate is the robust scale invariance in the non-Gaussian probability density function (PDF), which is preserved not only in a quiescent condition, but also in a dynamic state during waking hours [K. Kiyono et al. Phys. Rev. Lett. 93 (2004)]. Together with 1/f like scaling, this characteristic is a strong indication of far-from-equilibrium, critical-like dynamics of heart rate regulation. Our results suggest that healthy human heart rate departs from a critical state-like operation during sleeping hours, at a rate which is heterogeneous with respect to sleep stages annotated according to traditional techniques. We study specific contributions of sleep stages to the relative departure from criticality through the analysis of sleep stage dependence of the root mean square of multiscale local energy and the multiscale PDF. There is a possibility that the involvement of cortical activity may be important for a critical state-like operation.

  18. Chrysopa septempunctata (Neuroptera: Chrysopidae) Vitellogenin Functions Through Effects on Egg Production and Hatching.

    PubMed

    Liu, C; Mao, J; Zeng, F

    2015-12-01

    Vitellogenin (Vg) is a precursor of major egg storage protein, vitellin (Vt), and plays primary roles in reproduction of oviparous vertebrates and invertebrates. Chrysopa septempunctata Wesmael is an important and common predator of various insect pests. Here, we first cloned C. septempunctata Vg gene, CsVg. The complete CsVg cDNA was 5664 bp, which encodes an 1810-residues protein with a predicted molecular mass of 206.23 kDa. Expression profile revealed that CsVg mRNA first appeared on day 4 after emergence, maximally accumulated on day 10, and then declined gradually. RNAi mediated by injection of dsRNA depleted CsVg transcripts, significantly reduced egg-laying amount, and decreased egg hatching rate, suggesting that CsVg functions through effects on egg production and hatching in C. septempunctata. PMID:26470375

  19. Effect of nesting environment on incubation temperature and hatching success of Morelet's crocodile (Crocodylus moreletii) in an urban lake of Southeastern Mexico.

    PubMed

    López-Luna, Marco A; Hidalgo-Mihart, Mircea G; Aguirre-León, Gustavo; González-Ramón, Mariana Del C; Rangel-Mendoza, Judith A

    2015-01-01

    Incubation temperature is an important aspect in terms of biological performance among crocodiles, and several controlled experiments have demonstrated a significant relationship between incubation temperature, success in hatching and survival of hatchlings. However, a few studies have tested these relationships in the wild. The objective of this study was to determine the relationship of nest characteristics and environment (hatch year, nest basal area and height, clutch size, distance to shore line, and vegetation cover), to incubation temperature and hatching success among Morelet's crocodile (Crocodylus moreletii). The study was carried out during the nesting seasons of Morelet's crocodile, from 2007 to 2009 in the Laguna de Las Ilusiones, an urban lake located in Villahermosa, Tabasco, Mexico. We physically characterized 18 nests and inserted a temperature data logger in each nest chamber. At the end of the nesting season and prior to hatching, we recovered the crocodile eggs and data loggers and calculated hatching success, under laboratory conditions. We related the environmental variables of the nest with the mean and fluctuation (standard deviation) of nest temperature, using linear models. We also related the environmental variables affecting the nest, to mean nest temperature and fluctuation in incubation temperature and to hatching success, using linear models. Although we found differences in incubation temperature between nests, mean incubation temperature did not differ between years, but there were differences in nest thermal fluctuation between years. The mean incubation temperature for 11 nests (61.1%) was lower than the suggested Female-Male pivotal temperature (producing 50% of each sex) for this species, and all hatchlings obtained were males. There were no differences in clutch size between years, but hatching success varied. Our study indicates that hatching success depends on certain environmental variables and nest conditions to which the

  20. 9 CFR 93.205 - Certificate for live poultry and hatching eggs.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... hatching eggs. 93.205 Section 93.205 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE... hatching eggs. (a) Live poultry. All live poultry, except eggs for hatching, offered for importation from... eggs. All eggs for hatching offered for importation from any part of the world shall be accompanied...

  1. 9 CFR 93.205 - Certificate for live poultry and hatching eggs.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... hatching eggs. 93.205 Section 93.205 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE... hatching eggs. (a) Live poultry. All live poultry, except eggs for hatching, offered for importation from... eggs. All eggs for hatching offered for importation from any part of the world shall be accompanied...

  2. 9 CFR 93.205 - Certificate for live poultry and hatching eggs.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... hatching eggs. 93.205 Section 93.205 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE... hatching eggs. (a) Live poultry. All live poultry, except eggs for hatching, offered for importation from... eggs. All eggs for hatching offered for importation from any part of the world shall be accompanied...

  3. 9 CFR 82.9 - Interstate movement of hatching eggs from a quarantined area.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Interstate movement of hatching eggs... Interstate movement of hatching eggs from a quarantined area. Hatching eggs from birds or poultry not known...) The hatching eggs are accompanied by a permit obtained in accordance with § 82.11; (b) Copies of...

  4. 9 CFR 82.9 - Interstate movement of hatching eggs from a quarantined area.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Interstate movement of hatching eggs... Interstate movement of hatching eggs from a quarantined area. Hatching eggs from birds or poultry not known...) The hatching eggs are accompanied by a permit obtained in accordance with § 82.11; (b) Copies of...

  5. 9 CFR 82.9 - Interstate movement of hatching eggs from a quarantined area.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Interstate movement of hatching eggs... Interstate movement of hatching eggs from a quarantined area. Hatching eggs from birds or poultry not known...) The hatching eggs are accompanied by a permit obtained in accordance with § 82.11; (b) Copies of...

  6. 9 CFR 82.9 - Interstate movement of hatching eggs from a quarantined area.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Interstate movement of hatching eggs... Interstate movement of hatching eggs from a quarantined area. Hatching eggs from birds or poultry not known...) The hatching eggs are accompanied by a permit obtained in accordance with § 82.11; (b) Copies of...

  7. Evolutionary response of the egg hatching date of a herbivorous insect under climate change

    NASA Astrophysics Data System (ADS)

    van Asch, Margriet; Salis, Lucia; Holleman, Leonard J. M.; van Lith, Bart; Visser, Marcel E.

    2013-03-01

    Under changing climatic conditions, species need to adapt to their new environment. Genetic adaptation is crucial to prevent population extinction but examples where climate change leads to genetic changes in wild populations have been few. The synchronization between the timing of egg hatching of a herbivorous insect, the winter moth (Operophtera brumata), and the seasonal bud burst of its food plant, oak (Quercus robur), has been disrupted by climate change and a quantitative genetic model predicts that selection will delay the egg hatching date. Here we show, using both long-term observational data and experiments, that the egg hatching date has changed genetically, resulting in closer synchrony with oak bud burst. The observed rate of change matches the predicted rate of change of one day per year. Hence, altered selection pressures, caused by environmental change, result in a rapid adaptive response in insect phenology. These genetic changes in a key life-history trait in this herbivorous insect therefore seem to be fast enough to match the climate-change-induced advancement of their host phenology.

  8. Development of a Time-dependent Single-Rate Model and equivalence with MRMT

    NASA Astrophysics Data System (ADS)

    Sanchez-Vila, Xavier; Fernàndez-Garcia, Daniel

    2015-04-01

    Breakthrough curve tailing is a strong indication of non-Fickian mass transfer processes taking place over multiple scales. Yet, Haggerty et al. [2004] showed that in most experimental data it is possible to fit a single rate model provided that the single-rate mass transfer coefficient varies with exposure time. This paper studies the mathematical equivalence between the Multi-Rate Mass Transfer Model (MRMT) and a time-dependent single-rate mass transfer model (t-SRMT). We found that the t-SRMT model can be expressed by means of a memory function that is non-stationary. It was also found that the full behavior of the concentrations using a single time-dependent rate ω(t) is approximately analogous to that of the MRMT model provided that the equality ω(t)= -d ln g(t)/dt holds and the field capacity is properly chosen. This relationship suggests that when the memory function is a power law, g(t)˜ t1-k, the equivalent mass transfer coefficient scales as ω(t) ˜ t-1, nicely fitting without calibration the estimated mass transfer coefficients compiled by tep{Haggerty2004}.

  9. Intron-loss evolution of hatching enzyme genes in Teleostei

    PubMed Central

    2010-01-01

    Background Hatching enzyme, belonging to the astacin metallo-protease family, digests egg envelope at embryo hatching. Orthologous genes of the enzyme are found in all vertebrate genomes. Recently, we found that exon-intron structures of the genes were conserved among tetrapods, while the genes of teleosts frequently lost their introns. Occurrence of such intron losses in teleostean hatching enzyme genes is an uncommon evolutionary event, as most eukaryotic genes are generally known to be interrupted by introns and the intron insertion sites are conserved from species to species. Here, we report on extensive studies of the exon-intron structures of teleostean hatching enzyme genes for insight into how and why introns were lost during evolution. Results We investigated the evolutionary pathway of intron-losses in hatching enzyme genes of 27 species of Teleostei. Hatching enzyme genes of basal teleosts are of only one type, which conserves the 9-exon-8-intron structure of an assumed ancestor. On the other hand, otocephalans and euteleosts possess two types of hatching enzyme genes, suggesting a gene duplication event in the common ancestor of otocephalans and euteleosts. The duplicated genes were classified into two clades, clades I and II, based on phylogenetic analysis. In otocephalans and euteleosts, clade I genes developed a phylogeny-specific structure, such as an 8-exon-7-intron, 5-exon-4-intron, 4-exon-3-intron or intron-less structure. In contrast to the clade I genes, the structures of clade II genes were relatively stable in their configuration, and were similar to that of the ancestral genes. Expression analyses revealed that hatching enzyme genes were high-expression genes, when compared to that of housekeeping genes. When expression levels were compared between clade I and II genes, clade I genes tends to be expressed more highly than clade II genes. Conclusions Hatching enzyme genes evolved to lose their introns, and the intron-loss events occurred at

  10. STRAIN RATE AND TEMPERATURE DEPENDENT BEHAVIORS FOR TRANSFORMATION INDUCED PLASTICITY (TRIP) STEELS

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-01-03

    Base material properties for TRIP800 have been characterized under different automotive manufacturing and operating temperatures ranging from -40°C to 93°C, as well as strain rates ranging from 1/sec to 400/sec. Transformation kinetics for material points undergone high rate deformation has been quantified using a modified X-ray diffraction technique. The results clearly indicate the temperature dependency of the TRIP steel dynamic performance. At room temperature, the total elongation is around 33%, similar to those under quasi-static loading conditions. Under higher or lower temperature, however, TRIP800 has reduced ductility under dynamic loading.

  11. The rate dependence of the saturation flow stress of Cu and 1100 Al

    SciTech Connect

    Preston, D.L.; Tonks, D.L.; Wallace, D.C.

    1991-01-01

    The strain-rate dependence of the saturation flow stress of OFHC Cu and 1100 Al from 10{sup {minus}3}s{sup {minus}1} to nearly to 10{sup 12}s{sup {minus}1} is examined. The flow stress above 10{sup 9}s{sup {minus}1} is estimated using Wallace's theory of overdriven shocks in metals. A transition to the power-law behavior {Psi} {approximately} {tau}{sub s}{sup 5} occurs at a strain rate of order 10{sup 5}s{sup {minus}1}. 10 refs., 2 figs.

  12. New delay-dependent stability of Markovian jump neutral stochastic systems with general unknown transition rates

    NASA Astrophysics Data System (ADS)

    Kao, Yonggui; Wang, Changhong; Xie, Jing; Karimi, Hamid Reza

    2016-08-01

    This paper investigates the delay-dependent stability problem for neutral Markovian jump systems with generally unknown transition rates (GUTRs). In this neutral GUTR model, each transition rate is completely unknown or only its estimate value is known. Based on the study of expectations of the stochastic cross-terms containing the ? integral, a new stability criterion is derived in terms of linear matrix inequalities. In the mathematical derivation process, bounding stochastic cross-terms, model transformation and free-weighting matrix are not employed for less conservatism. Finally, an example is provided to demonstrate the effectiveness of the proposed results.

  13. Monitoring of ultraviolet pulse rate dependent photomechanical actuation in carbon nanotubes using fiber Bragg gratings

    SciTech Connect

    Shivananju, B. N.; Suri, Ashish; Asokan, S.; Misra, Abha

    2014-01-06

    In this Letter, we present a non-contact method of controlling and monitoring photomechanical actuation in carbon nanotubes (CNT) by exposing it to ultra-violet radiation at different pulse rates (10 to 200 Hz). This is accomplished by imparting a reversible photo induced strain (5–330 με) on CNT coated fibre Bragg gratings; CNT undergoes an internal reversible structural change due to cyclic photon absorption that leads to the development of mechanical strain, which in turn allows reversible switching of the Bragg wavelength. The results also reveal an interesting pulse rate dependent rise and fall times of photomechanical actuation in CNT.

  14. Scaling of viscous shear zones with depth-dependent viscosity and power-law stress-strain-rate dependence

    NASA Astrophysics Data System (ADS)

    Moore, James D. P.; Parsons, Barry

    2015-07-01

    One of the unresolved questions concerning fault deformation is the degree and cause of localization of shear at depth beneath a fault. Geologic observations of exhumed shear zones indicate that while the motion is no longer planar, it can still be localized near the down-dip extension of the fault; however, the degree of localization is uncertain. We employ simple analytic and numerical models to investigate the structural form of distributed shear beneath a strike-slip fault, and the relative importance of the physical mechanisms that have the potential to localize a shear zone. For a purely depth dependent viscosity, η = η0 exp (-z/z0), we find that a shear zone develops with a half-width δ _w˜ √{z_0} for small z0 at the base of the layer, where lengths are non-dimensionalized by the layer thickness (d km). Including a non-linear stress-strain-rate relation (dot{ɛ }∝ σ ^n) scales δw by 1/√{n}, comparable to deformation length scales in thin viscous sheet calculations. We find that the primary control on the shear-zone width is the depth dependence of viscosity that arises from the temperature dependence of viscosity and the increase in temperature with depth. As this relationship is exponential, scaling relations give a dimensional half-width that scales approximately as tilde{δ}_w≈ T_{1/2}√{Rd/nQβ } km, where T_{1/2} (K) is the temperature at the midpoint of the layer, R (J mol-1 K-1) the gas constant, Q (J mol-1) the activation energy and β (K km-1) the geothermal gradient. This relation predicts the numerical results for the parameter range consistent with continental rheologies to within 2-5 per cent and shear-zone half-widths from 2 to 6 km. The inclusion of shear-stress heating reduces δw by only an additional 5-25 per cent, depending on the initial width of the shear zone. While the width of the shear zone may not decrease significantly, local temperature increases from shear-stress heating range from 50 to 300 °C resulting in a

  15. The compliance of the porcine pulmonary artery depends on pressure and heart rate

    PubMed Central

    Kornet, L; Jansen, J R C; te Nijenhuis, F C A M; Langewouters, G J; Versprille, A

    1998-01-01

    The influence of mean pulmonary arterial pressure (mean Ppa) on dynamic (Cd) and pseudo-static compliance (Cps) of the pulmonary artery was studied at a constant and a changing heart rate. Cd is the change in cross-sectional area (CSA) relative to the change in Ppa throughout a heart cycle. Cps is the change in mean CSA relative to the change in mean Ppa. If Cd is known, pulmonary blood flow can be computed from the Ppa using a windkessel model. We investigated whether Cps can be interchanged with Cd. In nine anaesthetized pigs, we determined the mean CSA and Cd of the pulmonary artery at various Ppa levels, ranging from approximately 30 to 10 mmHg, established by bleeding. Two series of measurements were carried out, one series at a spontaneously changing heart rate (n = 9) and one series at a constant heart rate (n = 6). To determine CSA a conductance method was used. Cps depended on pressure. The mean CSA versus mean Ppa curves were sigmoid and steepest in the series with the increasing heart rate (established by bleeding). The CSA versus Ppa loop during a heart cycle, giving Cd, was approximately linear and almost closed. The Cdversus mean Ppa relationship was bell shaped. Its width was smaller if the heart rate increased during the series of measurements. The pressure, where Cd was maximum, was higher at higher heart rates. Furthermore, the maximum Cd was not affected by the heart rate. Because the pulmonary artery constricts with increasing heart rate, Cps will be overestimated during procedures where heart rate increases. Cd should be determined on a beat-to-beat basis to calculate flow because it changes with mean pulmonary arterial pressure and heart rate. PMID:9769432

  16. The compliance of the porcine pulmonary artery depends on pressure and heart rate.

    PubMed

    Kornet, L; Jansen, J R; Nijenhuis, F C; Langewouters, G J; Versprille, A

    1998-11-01

    1. The influence of mean pulmonary arterial pressure (mean Ppa) on dynamic (Cd) and pseudo-static compliance (Cps) of the pulmonary artery was studied at a constant and a changing heart rate. Cd is the change in cross-sectional area (CSA) relative to the change in Ppa throughout a heart cycle. Cps is the change in mean CSA relative to the change in mean Ppa. If Cd is known, pulmonary blood flow can be computed from the Ppa using a windkessel model. We investigated whether Cps can be interchanged with Cd. 2. In nine anaesthetized pigs, we determined the mean CSA and Cd of the pulmonary artery at various Ppa levels, ranging from approximately 30 to 10 mmHg, established by bleeding. Two series of measurements were carried out, one series at a spontaneously changing heart rate (n = 9) and one series at a constant heart rate (n = 6). To determine CSA a conductance method was used. 3. Cps depended on pressure. The mean CSA versus mean Ppa curves were sigmoid and steepest in the series with the increasing heart rate (established by bleeding). The CSA versus Ppa loop during a heart cycle, giving Cd, was approximately linear and almost closed. The Cd versus mean Ppa relationship was bell shaped. Its width was smaller if the heart rate increased during the series of measurements. The pressure, where Cd was maximum, was higher at higher heart rates. Furthermore, the maximum Cd was not affected by the heart rate. 4. Because the pulmonary artery constricts with increasing heart rate, Cps will be overestimated during procedures where heart rate increases. Cd should be determined on a beat-to-beat basis to calculate flow because it changes with mean pulmonary arterial pressure and heart rate. PMID:9769432

  17. Path dependent high strain, strain-rate deformation of polymer toroidal elements

    NASA Astrophysics Data System (ADS)

    Lee, Chien-Wei; Nesterenko, Vitali F.

    2014-08-01

    The dynamic behavior of toroidal elements (o-rings) is investigated at the range of global engineering strains up to 0.7 and strain rates about 100 s-1. It was observed that the corresponding average dynamic stiffness of rubber toroidal elements increases up to 3 times in comparison with their quasistatic compression. The viscoelastic dynamic model using linear strain-rate dependence and Hertz damped model did not satisfactory agree with experimental data in investigated range of strains and strain-rates. In order to reflect experimental results, a modified viscoelastic model with power-law strain-rate dependence was proposed. Path dependent deformation of o-rings with different levels of pre-compression was investigated under dynamic loading conditions. It was found that dynamic response of pre-compressed o-rings at the initial strain range of 0.04-0.25 is similar to the behavior of uncompressed o-rings, but further increasing pre-compression to 0.4 and 0.5 results in different force-strain curves demonstrating memory effect. This phenomenon is explained using a model incorporating dependence of dynamic force on initial pre-compression introducing critical level of dynamic strain, after which memory of initial pre-compression fades. This model predicts that force history of weakly compressed o-rings (initial strain 4%) on the stage of loading represents an envelope for all other data in agreement with experiments. In all cases, the dynamic behavior was characterized by stiffer force-displacement curves in comparison with quasistatic compression of o-rings.

  18. Improved model for the angular dependence of excimer laser ablation rates in polymer materials

    SciTech Connect

    Pedder, J. E. A.; Holmes, A. S.; Dyer, P. E.

    2009-10-26

    Measurements of the angle-dependent ablation rates of polymers that have applications in microdevice fabrication are reported. A simple model based on Beer's law, including plume absorption, is shown to give good agreement with the experimental findings for polycarbonate and SU8, ablated using the 193 and 248 nm excimer lasers, respectively. The modeling forms a useful tool for designing masks needed to fabricate complex surface relief by ablation.

  19. Optimal Control of Markov Processes with Age-Dependent Transition Rates

    SciTech Connect

    Ghosh, Mrinal K. Saha, Subhamay

    2012-10-15

    We study optimal control of Markov processes with age-dependent transition rates. The control policy is chosen continuously over time based on the state of the process and its age. We study infinite horizon discounted cost and infinite horizon average cost problems. Our approach is via the construction of an equivalent semi-Markov decision process. We characterise the value function and optimal controls for both discounted and average cost cases.

  20. Derivation of heating rate dependent exposure strategies for the selective laser melting of thermoplastic polymers

    NASA Astrophysics Data System (ADS)

    Drummer, Dietmar; Drexler, Maximilian; Wudy, Katrin

    2015-05-01

    The selective laser melting of polymer powder is for rapid prototyping applications an established technology, although a lack in basic process knowledge appears. Considering demands of series production the selective laser melting technique is faced with varies challenges concerning processable material systems, process strategies and part properties. Consequently basic research is necessary to shift from rapid prototyping to rapid manufacturing of small lot sized series. Based on basic research the high potential of selective laser melting for the production of complex parts without any tools can be opened up. For the derivation of part quality increasing process strategies knowledge about interactions between sub-processes of selective laser melting and resulting part properties is necessary. The selective laser melting consists of three major sub-processes: Geometry exposure, tempering and powder feeding. According to the interaction of sub-processes resulting temperature fields during the selective laser melting process determine the part properties by changing micro structural pore number and distribution. Beneath absolute temperatures also the time-dependency of the thermal fields influences the porosity of molten parts. Present process strategies tend to decrease building time by increasing scanning speed and laser power. Although the absolute energy input into the material is constant for increasing scanning speed and laser power in the same ratio, time dependent material effects are neglected. The heating rate is a combined parameter derived from absolute temperature and time. Within the paper the authors analyze the basic interactions between different heating rates and part properties (e.g. porosity, mechanical strengths). Therefore with different heating rates produced specimens are analyzed with imaging technologies as well as mechanical tests. Based on the done basic investigations new heating rate dependent process strategies can be established

  1. On rate-dependent polycrystal deformation: the temperature sensitivity of cold dwell fatigue

    PubMed Central

    Zhang, Zhen; Cuddihy, M. A.; Dunne, F. P. E.

    2015-01-01

    A temperature and rate-dependent crystal plasticity framework has been used to examine the temperature sensitivity of stress relaxation, creep and load shedding in model Ti-6Al polycrystal behaviour under dwell fatigue conditions. A temperature close to 120°C is found to lead to the strongest stress redistribution and load shedding, resulting from the coupling between crystallographic slip rate and slip system dislocation hardening. For temperatures in excess of about 230°C, grain-level load shedding from soft to hard grains diminishes because of the more rapid stress relaxation, leading ultimately to the diminution of the load shedding and hence, it is argued, the elimination of the dwell debit. Under conditions of cyclic stress dwell, at temperatures between 20°C and 230°C for which load shedding occurs, the rate-dependent accumulation of local slip by ratcheting is shown to lead to the progressive cycle-by-cycle redistribution of stress from soft to hard grains. This phenomenon is termed cyclic load shedding since it also depends on the material's creep response, but develops over and above the well-known dwell load shedding, thus providing an additional rationale for the incubation of facet nucleation. PMID:26528078

  2. Somatostatin analogue, octreotide, reduces increased glomerular filtration rate and kidney size in insulin-dependent diabetes

    SciTech Connect

    Serri, O.; Beauregard, H.; Brazeau, P.; Abribat, T.; Lambert, J.; Harris, A.; Vachon, L. Sandoz Canada Inc., Dorval, Quebec )

    1991-02-20

    To determine whether treatment with a somatostatin analogue can reduce kidney hyperfiltration and hypertrophy in insulin-dependent diabetes mellitus, the authors studied 11 patients with insulin-dependent diabetes mellitus and glomerular hyperfiltration. The patients were assigned randomly to receive continuous subcutaneous infusion of either octreotide, 300 {mu}g/24 h (five patients) or placebo (six patients) for 12 weeks. At baseline, mean glomerular filtration rate and mean total kidney volume were not significantly different in the two groups. However, after 12 weeks of treatment, the mean glomerular filtration rate was significantly lower in the octreotide group than in the placebo group. Furthermore, the mean total kidney volume was significantly lower after treatment in the octreotide group than in the placebo group. Glycemic control did not change significantly in either group. They conclude that subcutaneous infusion of octreotide for 12 weeks reduces increased glomerular filtration rate and kidney size in patients with insulin-dependent diabetes mellitus despite the fact that glycemic control remains unchanged.

  3. State-Dependent Pseudo-Linear Filter for Spacecraft Attitude and Rate Estimation

    NASA Technical Reports Server (NTRS)

    Bar-Itzhack, Itzhack Y.; Harman, Richard R.

    2001-01-01

    This paper presents the development and performance of a special algorithm for estimating the attitude and angular rate of a spacecraft. The algorithm is a pseudo-linear Kalman filter, which is an ordinary linear Kalman filter that operates on a linear model whose matrices are current state estimate dependent. The nonlinear rotational dynamics equation of the spacecraft is presented in the state space as a state-dependent linear system. Two types of measurements are considered. One type is a measurement of the quaternion of rotation, which is obtained from a newly introduced star tracker based apparatus. The other type of measurement is that of vectors, which permits the use of a variety of vector measuring sensors like sun sensors and magnetometers. While quaternion measurements are related linearly to the state vector, vector measurements constitute a nonlinear function of the state vector. Therefore, in this paper, a state-dependent linear measurement equation is developed for the vector measurement case. The state-dependent pseudo linear filter is applied to simulated spacecraft rotations and adequate estimates of the spacecraft attitude and rate are obtained for the case of quaternion measurements as well as of vector measurements.

  4. ANALYTICAL THEORY FOR THE INITIAL MASS FUNCTION. III. TIME DEPENDENCE AND STAR FORMATION RATE

    SciTech Connect

    Hennebelle, Patrick

    2013-06-20

    The present paper extends our previous theory of the stellar initial mass function (IMF) by including time dependence and by including the impact of the magnetic field. The predicted mass spectra are similar to the time-independent ones with slightly shallower slopes at large masses and peak locations shifted toward smaller masses by a factor of a few. Assuming that star-forming clumps follow Larson-type relations, we obtain core mass functions in good agreement with the observationally derived IMF, in particular, when taking into account the thermodynamics of the gas. The time-dependent theory directly yields an analytical expression for the star formation rate (SFR) at cloud scales. The SFR values agree well with the observational determinations of various Galactic molecular clouds. Furthermore, we show that the SFR does not simply depend linearly on density, as is sometimes claimed in the literature, but also depends strongly on the clump mass/size, which yields the observed scatter. We stress, however, that any SFR theory depends, explicitly or implicitly, on very uncertain assumptions like clump boundaries or the mass of the most massive stars that can form in a given clump, making the final determinations uncertain by a factor of a few. Finally, we derive a fully time dependent model for the IMF by considering a clump, or a distribution of clumps accreting at a constant rate and thus whose physical properties evolve with time. In spite of its simplicity, this model reproduces reasonably well various features observed in numerical simulations of converging flows. Based on this general theory, we present a paradigm for star formation and the IMF.

  5. Dose rate dependence of the current noise performance of an ultra-low noise precision bipolar operational amplifier

    SciTech Connect

    Hiemstra, D.M.

    1999-12-01

    The dose rate dependence of the current noise of a bipolar operational amplifier is presented. Total current noise performance degrades linearly with increasing dose rate. Generation-recombination, white and 1/f spectral components contribute to the degradation. The generation-recombination component is the most significant contributor to dose rate dependent current noise degradation.

  6. Time dependent heat transfer rates in high Reynolds number hypersonic flowfields

    NASA Technical Reports Server (NTRS)

    Flanagan, Michael J.

    1992-01-01

    Time dependent heat transfer rates have been calculated from time dependent temperature measurements in the vicinity of shock-wave boundary-layer interactions due to conical compression ramps on an axisymmetric body. The basic model is a cylindrical body with a 10 degree conical nose. Four conical ramps, 20, 25, 30, and 35 degrees serve as shock wave generators. Flowfield surveys have been made in the vicinity of the conical ramp vertex, the separation point, and the reattachment point. A significant effort was made to characterize the natural frequencies and relative powers of the resulting fluctuations in heat transfer rates. This research effort, sponsored jointly by NASA and the Air Force, was conducted in the Air Force Flight Dynamics Directorate High Reynolds Facility. The nominal freestream Mach number was 6, and the freestream Reynolds numbers ranged from 2.2 million/ft to 30.0 million/ft. Experimental results quantify temperature response and the resulting heat transfer rates as a function of ramp angle and Reynolds number. The temperature response within the flowfield appears to be steady-state for all compression ramp angles and all Reynolds numbers, and hence, the heat transfer rates appear to be steady-state.

  7. Automatic detection of key innovations, rate shifts, and diversity-dependence on phylogenetic trees.

    PubMed

    Rabosky, Daniel L

    2014-01-01

    A number of methods have been developed to infer differential rates of species diversification through time and among clades using time-calibrated phylogenetic trees. However, we lack a general framework that can delineate and quantify heterogeneous mixtures of dynamic processes within single phylogenies. I developed a method that can identify arbitrary numbers of time-varying diversification processes on phylogenies without specifying their locations in advance. The method uses reversible-jump Markov Chain Monte Carlo to move between model subspaces that vary in the number of distinct diversification regimes. The model assumes that changes in evolutionary regimes occur across the branches of phylogenetic trees under a compound Poisson process and explicitly accounts for rate variation through time and among lineages. Using simulated datasets, I demonstrate that the method can be used to quantify complex mixtures of time-dependent, diversity-dependent, and constant-rate diversification processes. I compared the performance of the method to the MEDUSA model of rate variation among lineages. As an empirical example, I analyzed the history of speciation and extinction during the radiation of modern whales. The method described here will greatly facilitate the exploration of macroevolutionary dynamics across large phylogenetic trees, which may have been shaped by heterogeneous mixtures of distinct evolutionary processes. PMID:24586858

  8. A microphysical interpretation of rate- and state-dependent friction for fault gouge

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.; Carpenter, Brett M.; Marone, Chris

    2016-05-01

    The evolution of fault strength during the seismic cycle plays a key role in the mode of fault slip, nature of earthquake stress drop, and earthquake nucleation. Laboratory-based rate- and state-dependent friction (RSF) laws can describe changes in fault strength during slip, but the connections between fault strength and the mechanisms that dictate the mode of failure, from aseismic creep to earthquake rupture, remain poorly understood. The empirical nature of RSF laws remains a drawback to their application in nature. Here we analyze an extensive data set of friction constitutive parameters with the goal of illuminating the microphysical processes controlling RSF. We document robust relationships between: (1) the initial value of sliding (or kinetic) friction, (2) RSF parameters, and (3) the time rates of frictional strengthening (aging). We derive a microphysical model based on asperity contact mechanics and show that these relationships are dictated by: (1) an activation energy that controls the rate of asperity growth by plastic creep, and (2) an inverse relationship between material hardness and the activation volume of plastic deformation. Collectively, our results illuminate the physics expressed by the RSF parameters, and which describe the absolute value of frictional strength and its dependence on time and slip rate. Moreover, we demonstrate that seismogenic fault behavior may be dictated by the interplay between grain properties and ambient conditions controlling the local shear strength of grain-scale asperity contacts.

  9. Automatic Detection of Key Innovations, Rate Shifts, and Diversity-Dependence on Phylogenetic Trees

    PubMed Central

    Rabosky, Daniel L.

    2014-01-01

    A number of methods have been developed to infer differential rates of species diversification through time and among clades using time-calibrated phylogenetic trees. However, we lack a general framework that can delineate and quantify heterogeneous mixtures of dynamic processes within single phylogenies. I developed a method that can identify arbitrary numbers of time-varying diversification processes on phylogenies without specifying their locations in advance. The method uses reversible-jump Markov Chain Monte Carlo to move between model subspaces that vary in the number of distinct diversification regimes. The model assumes that changes in evolutionary regimes occur across the branches of phylogenetic trees under a compound Poisson process and explicitly accounts for rate variation through time and among lineages. Using simulated datasets, I demonstrate that the method can be used to quantify complex mixtures of time-dependent, diversity-dependent, and constant-rate diversification processes. I compared the performance of the method to the MEDUSA model of rate variation among lineages. As an empirical example, I analyzed the history of speciation and extinction during the radiation of modern whales. The method described here will greatly facilitate the exploration of macroevolutionary dynamics across large phylogenetic trees, which may have been shaped by heterogeneous mixtures of distinct evolutionary processes. PMID:24586858

  10. STRONG DEPENDENCE OF THE INNER EDGE OF THE HABITABLE ZONE ON PLANETARY ROTATION RATE

    SciTech Connect

    Yang, Jun; Abbot, Dorian S.; Boué, Gwenaël; Fabrycky, Daniel C.

    2014-05-20

    Planetary rotation rate is a key parameter in determining atmospheric circulation and hence the spatial pattern of clouds. Since clouds can exert a dominant control on planetary radiation balance, rotation rate could be critical for determining the mean planetary climate. Here we investigate this idea using a three-dimensional general circulation model with a sophisticated cloud scheme. We find that slowly rotating planets (like Venus) can maintain an Earth-like climate at nearly twice the stellar flux as rapidly rotating planets (like Earth). This suggests that many exoplanets previously believed to be too hot may actually be habitable, depending on their rotation rate. The explanation for this behavior is that slowly rotating planets have a weak Coriolis force and long daytime illumination, which promotes strong convergence and convection in the substellar region. This produces a large area of optically thick clouds, which greatly increases the planetary albedo. In contrast, on rapidly rotating planets a much narrower belt of clouds form in the deep tropics, leading to a relatively low albedo. A particularly striking example of the importance of rotation rate suggested by our simulations is that a planet with modern Earth's atmosphere, in Venus' orbit, and with modern Venus' (slow) rotation rate would be habitable. This would imply that if Venus went through a runaway greenhouse, it had a higher rotation rate at that time.

  11. On the rate dependence of mechanical properties of aligned carbon nanotube arrays

    NASA Astrophysics Data System (ADS)

    Lu, Y. C.; Zhang, Q.; Dai, L.; Baur, J.

    2015-08-01

    Aligned carbon nanotube arrays are a new form of carbon nanomaterials that have received great interest due to their superior structure and properties. The present work comprehensively examines the rate-dependent mechanical deformation of the vertically aligned carbon nanotube arrays (VA-CNTs) by the use of indentation tests. The small-displacement, elastic property of the VA-CNTs was measured by a spherical indenter. The effective indentation strain rate was varied by adjusting the indenter unloading rate. The instantaneous modulus of the VA-CNTs has been calculated and is found to increase linearly with indentation strain rate. The large-displacement, plastic property of the VA-CNTs was measured by a cylindrical, flat-ended indenter. At large indentation depths, the stress-strain curve of the VA-CNTs reveals distinct plastic deformation. The indentation strain rate was varied by directly changing the indenter velocity. The yield strength ( σ y) of the VA-CNTs also increases linearly with respect to indentation strain rate.

  12. Dose dependent effect of GnRH analogue on pregnancy rate of repeat breeder crossbred cows.

    PubMed

    Kharche, S D; Srivastava, S K

    2007-05-01

    The aim of this study was to investigate the effect of treating repeat breeder dairy crossbred cows with different doses of GnRH analogue through i.m. at the time of artificial insemination, on pregnancy rates from their first service after treatment and overall pregnancy rates. One hundred and thirty seven crossbred dairy cows with a history of repeat breeding and eligible after 6-8 infertile services but clinically free of diseases were selected for the study. The animals were randomly divided into three groups. Group 1 (n = 55) cows were treated intramuscularly with each 20 microg Buserelin-acetate (Receptal, Hoechst Roussel Vet GmbH) at the time of artificial insemination. Group 2 (n = 40) cows were treated intramuscularly with each 10 microg Buserelin-acetate at the time of artificial insemination. Group 3 (n = 42) cows were treated intramuscularly with saline as control at the time of artificial insemination. The first service pregnancy rates in Groups 1-3 were 45, 25 and 17%, respectively. Similarly, the overall conception rates in Groups 1-3 were 87, 58 and 48%, respectively. The results indicated that the pregnancy rate in crossbred cows could be improved by the GnRH treatment. The higher dose of GnRH significantly increased (P < 0.05) the first service as well as overall pregnancy rate in a dose dependent manner in repeat breeder crossbred cow bred previously 6-8 times unsuccessfully. PMID:16787717

  13. Gaussian free-energy dependence of electron-transfer rates in iridium complexes

    SciTech Connect

    Fox, L.S.; Gray, H.B. ); Kozik, M.; Winkler, J.R. )

    1990-03-02

    The kinetics of photoinduced electron-transfer (ET) reactions have been measured in a series of synthetic donor-acceptor complexes. The electron donors are singlet or triplet excited iridium(I) dimers (Ir{sub 2}), and the acceptors are N-alkylpyridinium groups covalently bound to phosphinite ligands on the Ir{sub 2} core. Rate constants for excited-state ET range from 3.5 {times} 10{sup 6} to 1.1 {times} 10{sup 11} per second, and thermal back ET (pyridinium radical to Ir{sub 2}{sup +}) rates vary from 2.0 {times} 10{sup 10} to 6.7 {times} 10{sup 7} per second. The variation of these rates with driving force is in remarkably good agreement with the Marcus theory prediction of a Gaussian free-energy dependence. 26 refs., 2 figs., 2 tabs.

  14. Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

    NASA Astrophysics Data System (ADS)

    Alpert, P. A.; Knopf, D. A.

    2015-05-01

    Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature (T) and relative humidity (RH) at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling rate dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nuclei (IN) all have the same IN surface area (ISA), however the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses physically observable parameters including the total number of droplets (Ntot) and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets, droplets in a continuous flow diffusion chamber (CFDC), the Leipzig aerosol cloud interaction simulator (LACIS), and the aerosol interaction and dynamics in the atmosphere (AIDA) cloud chamber. Observed time dependent isothermal frozen fractions exhibiting non-exponential behavior with time can be readily explained by this model considering varying ISA. An

  15. PH-dependence of the steady-state rate of a two-step enzymic reaction.

    PubMed

    Brocklehurst, K; Dixon, H B

    1976-04-01

    1. The pH-dependence is considered of a reaction between E and S that proceeds through an intermediate ES under "Briggs-Haldane' conditions, i.e. there is a steady state in ES and [S]o greater than [E]T, where [S]o is the initial concentration of S and [E]T is the total concentration of all forms of E. Reactants and intermediates are assumed to interconvert in three protonic states (E equilibrium ES; EH equilibrium EHS; EH2 equilibrium EH2S), but only EHS provides products by an irreversible reaction whose rate constant is kcat. Protonations are assumed to be so fast that they are all at equilibrium. 2. The rate equation for this model is shown to be v = d[P]/dt = (kcat.[E]T[S]o/A)/[(KmBC/DA) + [S]o], where Km is the usual assembly of rate constants around EHS and A-D are functions of the form (1 + [H]/K1 + K2/[H]), in which K1 and K2 are: in A, the molecular ionization constants of ES; in B, the analogous constants of E; in C and D, apparent ionization constants composed of molecular ionization constants (of E or ES) and assemblies of rate constants. 3. As in earlier treatments of this type of reaction which involve either the assumption that the reactants and intermediate are in equilibrium or the assumption of Peller & Alberty [(1959) J. Am. Chem. Soc. 81, 5907-5914] that only EH and EHS interconvert directly, the pH-dependence of kcat. is determined only by A. 4. The pH-dependence of Km is determined in general by B-C/A-D, but when reactants and intermediate are in equilibrium, C identical to D and this expression simplifies to B/A. 5. The pH-dependence of kcat./Km, i.e. of the rate when [S]o less than Km, is not necessarily a simple bell-shaped curve characterized only by the ionization constants of B, but is a complex curve characterized by D/B-C. 6. Various situations are discussed in which the pH-dependence of kcat./Km is determined by assemblies simpler than D/B-C. The special situation in which a kcat./Km-pH profile provides the molecular pKa values of

  16. Computational microstructure modeling of asphalt mixtures subjected to rate-dependent fracture

    NASA Astrophysics Data System (ADS)

    Aragao, Francisco Thiago Sacramento

    2011-12-01

    Computational microstructure models have been actively pursued by the pavement mechanics community as a promising and advantageous alternative to limited analytical and semi-empirical modeling approaches. The primary goal of this research is to develop a computational microstructure modeling framework that will eventually allow researchers and practitioners of the pavement mechanics community to evaluate the effects of constituents and mix design characteristics (some of the key factors directly affecting the quality of the pavement structures) on the mechanical responses of asphalt mixtures. To that end, the mixtures are modeled as heterogeneous materials with inelastic mechanical behavior. To account for the complex geometric characteristics of the heterogeneous mixtures, an image treatment process is used to generate finite element meshes that closely reproduce the geometric characteristics of aggregate particles (size, shape, and volume fraction) that are distributed within a fine aggregate asphaltic matrix (FAM). These two mixture components, i.e., aggregate particles and FAM, are modeled, respectively, as isotropic linear elastic and isotropic linear viscoelastic materials and the material properties required as inputs for the computational model are obtained from simple and expedited laboratory tests. In addition to the consideration of the complex geometric characteristics and inelastic behavior of the mixtures, this study uses the cohesive zone model to simulate fracture as a gradual and rate-dependent phenomenon in which the initiation and propagation of discrete cracks take place in different locations of the mixture microstructure. Rate-dependent cohesive zone fracture properties are obtained using a procedure that combines laboratory tests of semi-circular bending specimens of the FAM and their numerical simulations. To address the rate-dependent fracture characteristics of the FAM phase, a rate-dependent cohesive zone model is developed and

  17. Rate sensitive continuum damage models and mesh dependence in finite element analyses.

    PubMed

    Ljustina, Goran; Fagerström, Martin; Larsson, Ragnar

    2014-01-01

    The experiences from orthogonal machining simulations show that the Johnson-Cook (JC) dynamic failure model exhibits significant element size dependence. Such mesh dependence is a direct consequence of the utilization of local damage models. The current contribution is an investigation of the extent of the possible pathological mesh dependence. A comparison of the resulting JC model behavior combined with two types of damage evolution is considered. The first damage model is the JC dynamic failure model, where the development of the "damage" does not affect the response until the critical state is reached. The second one is a continuum damage model, where the damage variable is affecting the material response continuously during the deformation. Both the plasticity and the damage models are rate dependent, and the damage evolutions for both models are defined as a postprocessing of the effective stress response. The investigation is conducted for a series of 2D shear tests utilizing different FE representations of the plane strain plate with pearlite material properties. The results show for both damage models, using realistic pearlite material parameters, that similar extent of the mesh dependence is obtained and that the possible viscous regularization effects are absent in the current investigation. PMID:25530994

  18. Rate Sensitive Continuum Damage Models and Mesh Dependence in Finite Element Analyses

    PubMed Central

    Fagerström, Martin

    2014-01-01

    The experiences from orthogonal machining simulations show that the Johnson-Cook (JC) dynamic failure model exhibits significant element size dependence. Such mesh dependence is a direct consequence of the utilization of local damage models. The current contribution is an investigation of the extent of the possible pathological mesh dependence. A comparison of the resulting JC model behavior combined with two types of damage evolution is considered. The first damage model is the JC dynamic failure model, where the development of the “damage” does not affect the response until the critical state is reached. The second one is a continuum damage model, where the damage variable is affecting the material response continuously during the deformation. Both the plasticity and the damage models are rate dependent, and the damage evolutions for both models are defined as a postprocessing of the effective stress response. The investigation is conducted for a series of 2D shear tests utilizing different FE representations of the plane strain plate with pearlite material properties. The results show for both damage models, using realistic pearlite material parameters, that similar extent of the mesh dependence is obtained and that the possible viscous regularization effects are absent in the current investigation. PMID:25530994

  19. Age-Related Degeneration of the Egg-Laying System Promotes Matricidal Hatching in Caenorhabditis elegans

    PubMed Central

    Pickett, Christopher L.; Kornfeld, Kerry

    2014-01-01

    Summary The identification and characterization of age-related degenerative changes is a critical goal because it can elucidate mechanisms of aging biology and contribute to understanding interventions that promote longevity. Here we document a novel, age-related degenerative change in C. elegans hermaphrodites, an important model system for the genetic analysis of longevity. Matricidal hatching—intra-uterine hatching of progeny that causes maternal death—displayed an age-related increase in frequency and affected ∼70% of mated, wild-type hermaphrodites. The timing and incidence of matricidal hatching were largely independent of the levels of early and total progeny production and the duration of male exposure. Thus, matricidal hatching appears to reflect intrinsic age-related degeneration of the egg-laying system rather than use-dependent damage accumulation. Consistent with this model, mutations that extend longevity by causing dietary restriction significantly delayed matricidal hatching, indicating age-related degeneration of the egg-laying system is controlled by nutrient availability. To identify the underlying tissue defect, we analyzed serotonin signaling that triggers vulval muscle contractions. Mated hermaphrodites displayed an age-related decline in the ability to lay eggs in response to exogenous serotonin, indicating that vulval muscles and/or a further downstream function that is necessary for egg-laying degenerate in an age-related manner. By characterizing a new, age-related degenerative event displayed by C. elegans hermaphrodites, these studies contribute to understanding a frequent cause of death in mated hermaphrodites and establish a model of age-related reproductive complications that may be relevant to the birthing process in other animals such as humans. PMID:23551912

  20. Should we maintain baby hatches in our society?

    PubMed Central

    2013-01-01

    Background A baby hatch called the “Stork’s Cradle” has been in place at Jikei Hospital in Kumamoto City, Japan, since May 10, 2007. Babyklappes were first established in Germany in 2000, and there are currently more than 90 locations. Attitudes regarding baby hatches are divided in Japan and neither opinions for nor against baby hatches have thus far been overwhelming. To consider the appropriateness of baby hatches, we present and examine the validity of each major objection to establishing baby hatches. Discussion There are various objections to baby hatches as follows: It violates a child’s right to know the identity of his or her biological parents by allowing anonymous birth; it neglects fulfillment of the biological parents’ basic obligation to raise their child and its very availability induces abandonment of infants; some people abuse it for very selfish reasons; it cannot save babies’ lives; the rights of one parent can be ignored if the other surrenders a child without his or her consent; it puts a baby in medical jeopardy; and it has no clear legal basis. The authors would argue that there are many plausible refutations for each objection mainly based on priority of child’s right to life, pregnant women’s vulnerability and necessity of anonymity, social responsibility to protect and raise children, differences between dropping a child off at a baby hatch and child neglect, limited function of social childcare center, inevitability of abuse by a minority of people, necessary distinction between outcomes that occur only because baby hatches exist and those that occur regardless of their existence, important local direct and upmost measures for women in trouble, and difference between ambiguous legality and illegality. Summary We argue that a certain number of baby hatches should continue to be established as a last resort, in a form that can maintain anonymity if the parent dropping the child off so desires. It should be supported if it is

  1. Strain Rate Dependency of Bronze Metal Matrix Composite Mechanical Properties as a Function of Casting Technique

    NASA Astrophysics Data System (ADS)

    Brown, Lloyd; Joyce, Peter; Radice, Joshua; Gregorian, Dro; Gobble, Michael

    2012-07-01

    Strain rate dependency of mechanical properties of tungsten carbide (WC)-filled bronze castings fabricated by centrifugal and sedimentation-casting techniques are examined, in this study. Both casting techniques are an attempt to produce a functionally graded material with high wear resistance at a chosen surface. Potential applications of such materials include shaft bushings, electrical contact surfaces, and brake rotors. Knowledge of strain rate-dependent mechanical properties is recommended for predicting component response due to dynamic loading or impact events. A brief overview of the casting techniques for the materials considered in this study is followed by an explanation of the test matrix and testing techniques. Hardness testing, density measurement, and determination of the volume fraction of WC particles are performed throughout the castings using both image analysis and optical microscopy. The effects of particle filling on mechanical properties are first evaluated through a microhardness survey of the castings. The volume fraction of WC particles is validated using a thorough density survey and a rule-of-mixtures model. Split Hopkinson Pressure Bar (SHPB) testing of various volume fraction specimens is conducted to determine strain dependence of mechanical properties and to compare the process-property relationships between the two casting techniques. The baseline performances of C95400 bronze are provided for comparison. The results show that the addition of WC particles improves microhardness significantly for the centrifugally cast specimens, and, to a lesser extent, in the sedimentation-cast specimens, largely because the WC particles are more concentrated as a result of the centrifugal-casting process. Both metal matrix composites (MMCs) demonstrate strain rate dependency, with sedimentation casting having a greater, but variable, effects on material response. This difference is attributed to legacy effects from the casting process, namely

  2. 50 CFR Figure 1 to Subpart I of... - Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Existing California Area Closures (hatched areas extend to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional... to 3 miles offshore; cross-hatched areas extend beyond 3 miles offshore) and Optional...

  3. Rate-dependence of 'wet' biological adhesives and the function of the pad secretion in insects.

    PubMed

    Labonte, David; Federle, Walter

    2015-11-28

    Many insects use soft adhesive footpads for climbing. The surface contact of these organs is mediated by small volumes of a liquid secretion, which forms thin films in the contact zone. Here, we investigate the role of viscous dissipation by this secretion and the 'bulk' pad cuticle by quantifying the rate-dependence of the adhesive force of individual pads. Adhesion increased with retraction speed, but this effect was independent of the amount of pad secretion present in the contact zone, suggesting that the secretion's viscosity did not play a significant role. Instead, the rate-dependence can be explained by relating the strain energy release rate to the speed of crack propagation, using an established empirical power law. The 'wet' pads' behaviour was akin to that of 'dry' elastomers, with an equilibrium energy release rate close to that of dry van-der-Waals contacts. We suggest that the secretion mainly serves as a 'release layer', minimising viscous dissipation and thereby reducing the time- and 'loading-history'-dependence of the adhesive pads. In contrast to many commercial adhesives which derive much of their strength from viscous dissipation, we show that the major modulator of adhesive strength in 'wet' biological adhesive pads is friction, exhibiting a much larger effect than retraction speed. A comparison between 'wet' and 'dry' biological adhesives, using both results from this study and the literature, revealed a striking lack of differences in attachment performance under varying experimental conditions. Together, these results suggest that 'wet' and 'dry' biological adhesives may be more similar than previously thought. PMID:26376599

  4. A viscoelastic damage rheology and rate- and state-dependent friction

    NASA Astrophysics Data System (ADS)

    Lyakhovsky, Vladimir; Ben-Zion, Yehuda; Agnon, Amotz

    2005-04-01

    We analyse the relations between a viscoelastic damage rheology model and rate- and state-dependent (RS) friction. Both frameworks describe brittle deformation, although the former models localization zones in a deforming volume while the latter is associated with sliding on existing surfaces. The viscoelastic damage model accounts for evolving elastic properties and inelastic strain. The evolving elastic properties are related quantitatively to a damage state variable representing the local density of microcracks. Positive and negative changes of the damage variable lead, respectively, to degradation and recovery of the material in response to loading. A model configuration having an existing narrow zone with localized damage produces for appropriate loading and temperature-pressure conditions an overall cyclic stick-slip motion compatible with a frictional response. Each deformation cycle (limit cycle) can be divided into healing and weakening periods associated with decreasing and increasing damage, respectively. The direct effect of the RS friction and the magnitude of the frictional parameter a are related to material strengthening with increasing rate of loading. The strength and residence time of asperities (model elements) in the weakening stage depend on the rates of damage evolution and accumulation of irreversible strain. The evolutionary effect of the RS friction and overall change in the friction parameters (a-b) are controlled by the duration of the healing period and asperity (element) strengthening during this stage. For a model with spatially variable properties, the damage rheology reproduces the logarithmic dependency of the steady-state friction coefficient on the sliding velocity and the normal stress. The transition from a velocity strengthening regime to a velocity weakening one can be obtained by varying the rate of inelastic strain accumulation and keeping the other damage rheology parameters fixed. The developments unify previous damage

  5. Atmospheric General Circulations of Synchronously Rotating Terrestrial Planets: Dependence on Planetary Rotation Rate

    NASA Astrophysics Data System (ADS)

    Noda, S.; Ishiwatari, M.; Nakajima, K.; Takahashi, Y. O.; Morikawa, Y.; Nishizawa, S.; Hayashi, Y.-Y.

    2012-04-01

    In order to investigate a variety of climates of synchronously rotating terrestrial planets, a parameter study on the dependence on planetary rotation rate Ω is performed by using a general circulation model (GCM) with simplified hydrologic and radiative processes. The planetary rotation rate is varied from zero to the Earth's value, and other parameters such as orbital parameters, planetary radius, solar constant are set to the Earth's values. The results show that there emerge four typical atmospheric states in ascending order of planetary rotation rate as follows: States in which dayside-nightside direct circulations dominate States in which weak super rotation emerges States in which strong super rotation emerges and meridionally asymmetric patterns oscillate States in which precipitation disturbances emerge in nightside midlatitudinal regions The atmospheric state is gradually accompanied by a qualitative circulation change from state (1) to state (3) with increasing Ω from zero, although Merlis and Schneider (2010) which performed similar GCM experiments lump together cases with small planetary rotation rates under the term "slowly rotating atmospheres". For cases for planetary rotation rate with the values of 0.75-0.85 times of the terrestrial value, multiple equilibrium solutions of state (3) and state (4) are obtained. It is shown that, in addition to dry atmosphere (Edson et al., 2011), moist atmospheres on synchronously rotating planet also have multiple equilibrium solutions. Although circulation patterns and amount of sensible/latent heat transport from the dayside to the nightside changes with the change of Ω, summation of sensible heat transport and latent heat transport almost remains unchanged, and the dependence of dayside to nightside temperature contrast on Ω is small.

  6. Strain-rate Dependence of Elastic Modulus Reveals Silver Nanoparticle Induced Cytotoxicity

    PubMed Central

    Caporizzo, Matthew Alexander; Roco, Charles M.; Ferrer, Maria Carme Coll; Grady, Martha E.; Parrish, Emmabeth; Eckmann, David M.; Composto, Russell John

    2015-01-01

    Force-displacement measurements are taken at different rates with an atomic force microscope to assess the correlation between cell health and cell viscoelasticity in THP-1 cells that have been treated with a novel drug carrier. A variable indentation-rate viscoelastic analysis, VIVA, is employed to identify the relaxation time of the cells that are known to exhibit a frequency dependent stiffness. The VIVA agrees with a fluorescent viability assay. This indicates that dextran-lysozyme drug carriers are biocompatible and deliver concentrated toxic material (rhodamine or silver nanoparticles) to the cytoplasm of THP-1 cells. By modelling the frequency dependence of the elastic modulus, the VIVA provides three metrics of cytoplasmic viscoelasticity: a low frequency modulus, a high frequency modulus and viscosity. The signature of cytotoxicity by rhodamine or silver exposure is a frequency independent twofold increase in the elastic modulus and cytoplasmic viscosity, while the cytoskeletal relaxation time remains unchanged. This is consistent with the known toxic mechanism of silver nanoparticles, where metabolic stress causes an increase in the rigidity of the cytoplasm. A variable indentation-rate viscoelastic analysis is presented as a straightforward method to promote the self-consistent comparison between cells. This is paramount to the development of early diagnosis and treatment of disease. PMID:26834855

  7. Model misspecification confounds the estimation of rates and exaggerates their time dependency.

    PubMed

    Emerson, Brent C; Alvarado-Serrano, Diego F; Hickerson, Michael J

    2015-12-01

    While welcoming the comment of Ho et al. (2015), we find little that undermines the strength of our criticism, and it would appear they have misunderstood our central argument. Here we respond with the purpose of reiterating that we are (i) generally critical of much of the evidence presented in support of the time-dependent molecular rate (TDMR) hypothesis and (ii) specifically critical of estimates of μ derived from tip-dated sequences that exaggerate the importance of purifying selection as an explanation for TDMR over extended timescales. In response to assertions put forward by Ho et al. (2015), we use panmictic coalescent simulations of temporal data to explore a fundamental assumption for tip-dated tree shape and associated mutation rate estimates, and the appropriateness and utility of the date randomization test. The results reveal problems for the joint estimation of tree topology, effective population size and μ with tip-dated sequences using BEAST. Given the simulations, BEAST consistently obtains incorrect topological tree structures that are consistent with the substantial overestimation of μ and underestimation of effective population size. Data generated from lower effective population sizes were less likely to fail the date randomization test yet still resulted in substantially upwardly biased estimates of rates, bringing previous estimates of μ from temporally sampled DNA sequences into question. We find that our general criticisms of both the hypothesis of time-dependent molecular evolution and Bayesian methods to estimate μ from temporally sampled DNA sequences are further reinforced. PMID:26769403

  8. Notch Fracture Toughness of Glasses: Dependence on Rate, Age, and Geometry

    NASA Astrophysics Data System (ADS)

    Vasoya, Manish; Rycroft, Chris H.; Bouchbinder, Eran

    2016-08-01

    Understanding the fracture toughness (resistance) of glasses is a fundamental problem of prime theoretical and practical importance. Here we theoretically study its dependence on the loading rate, the age (history) of the glass, and the notch radius ρ . Reduced-dimensionality analysis suggests that the notch fracture toughness results from a competition between the initial, age- and history-dependent, plastic relaxation time scale τ0pl and an effective loading time scale τext(K˙ I,ρ ) , where K˙ I is the tensile stress-intensity-factor rate. The toughness is predicted to scale with √{ρ } independently of ξ ≡τext/τ0pl for ξ ≪1 , to scale as T √{ρ }log (ξ ) for ξ ≫1 (related to thermal activation, where T is the temperature), and to feature a nonmonotonic behavior in the crossover region ξ ˜O (1 ) (related to plastic yielding dynamics). These predictions are verified using 2D computations, providing a unified picture of the notch fracture toughness of glasses. The theory highlights the importance of time-scale competition and far-from-steady-state elasto-viscoplastic dynamics for understanding the toughness and shows that the latter varies quite significantly with the glass age (history) and applied loading rate. Experimental support for bulk metallic glasses is presented, and possible implications for applications are discussed.

  9. Rate-Dependent Embedded Discontinuity Approach Incorporating Heterogeneity for Numerical Modeling of Rock Fracture

    NASA Astrophysics Data System (ADS)

    Saksala, Timo

    2015-07-01

    In this paper, the embedded discontinuity approach is applied in finite element modeling of rock in compression and tension. For this end, a rate-dependent constitutive model based on (strong) embedded displacement discontinuity model is developed to describe the mode I, mode II and mixed mode fracture of rock. The constitutive model describes the bulk material as linear elastic until reaching the elastic limit. Beyond the elastic limit, the rate-dependent exponential softening law governs the evolution of the displacement jump. Rock heterogeneity is incorporated in the present approach by random description of the mineral texture of rock. Moreover, initial microcrack population always present in natural rocks is accounted for as randomly-oriented embedded discontinuities. In the numerical examples, the model properties are extensively studied in uniaxial compression. The effect of loading rate and confining pressure is also tested in the 2D (plane strain) numerical simulations. These simulations demonstrate that the model captures the salient features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it also has the advantage, over these models, of accounting for the orientation of introduced microcracks. This feature is crucial with respect to the fracture behavior of rock in compression as shown in this paper.

  10. ATP Dependence of the ICl, swell Channel Varies with Rate of Cell Swelling

    PubMed Central

    Bond, Tamara; Basavappa, Srisaila; Christensen, Michael; Strange, Kevin

    1999-01-01

    Swelling-induced activation of the outwardly rectifying anion current, ICl, swell, is modulated by intracellular ATP. The mechanisms by which ATP controls channel activation, however, are unknown. Whole cell patch clamp was employed to begin addressing this issue. Endogenous ATP production was inhibited by dialyzing N1E115 neuroblastoma cells for 4–5 min with solutions containing (μM): 40 oligomycin, 5 iodoacetate, and 20 rotenone. The effect of ATP on current activation was observed in the absence of intracellular Mg2+, in cells exposed to extracellular metabolic inhibitors for 25–35 min followed by intracellular dialysis with oligomycin, iodoacetate, and rotenone, after substitution of ATP with the nonhydrolyzable analogue AMP-PNP, and in the presence of AMP-PNP and alkaline phosphatase to dephosphorylate intracellular proteins. These results demonstrate that the ATP dependence of the channel requires ATP binding rather than hydrolysis and/or phosphorylation reactions. When cells were swollen at 15–55%/min in the absence of intracellular ATP, current activation was slow (0.3–0.8 pA/pF per min). ATP concentration increased the rate of current activation up to maximal values of 4–6 pA/pF per min, but had no effect on the sensitivity of the channel to cell swelling. Rate of current activation was a saturable, hyperbolic function of ATP concentration. The EC50 for ATP varied inversely with the rate of cell swelling. Activation of current was rapid (4–6 pA/pF per min) in the absence of ATP when cells were swollen at rates ≥65%/min. Intracellular ATP concentration had no effect on current activation induced by high rates of swelling. Current activation was transient when endogenous ATP was dialyzed out of the cytoplasm of cells swollen at 15%/min. Rundown of the current was reversed by increasing the rate of swelling to 65%/min. These results indicate that the channel and/or associated regulatory proteins are capable of sensing the rate of cell volume

  11. Energy-Dependent Metric for Gravitation from Clock-Rate Experiments

    NASA Astrophysics Data System (ADS)

    Cardone, Fabio; Mignani, Roberto

    We carry out a detailed analysis of the data on the comparison of clock rates between a flying clock and a clock at ground, performed by Alley and co-workers at the end of 1970's. The fit to such data is in favor of an energy-dependent metric for gravitation, whose time coefficient is at variance with the standard Einsteinian one in the weak-field approximation. By exploiting the formalism of a deformed Minkowski space-time, with metric coefficients dependent on the energy, we show that a possible lower limit on the propagation speed of gravitational effects is about 1010c, in agreement with a recent analysis by Van Flandern based on the acceleration of binary systems.

  12. Temperature dependence of the atmospheric photolysis rate coefficient for NO2

    NASA Technical Reports Server (NTRS)

    Shetter, Richard E.; Davidson, James A.; Cantrell, Christopher A.; Burzysnki, Norbert J., Jr.; Calvert, Jack G.

    1988-01-01

    Accurate values for the photolysis rate coefficient of NO2 (j1) are required for studies related to the observed imbalance in the photostationary state of O3, NO, and NO2 in the troposphere. Direct measurements of the temperature dependence of j1 at temperatures from -70 to 30 C were made in sunlight for relatively cloudless summer days in Boulder, Colorado. The ratios of j1 (30 C)/j1 (T C) for T = -10 C and -70 C, respectively, were 1.046 + or - 0.040 and 1.070 + or - 0.031. The j1 ratios were independent of solar zenith angle. Theoretical estimates of the temperature-dependent j1 ratios based upon recently reported cross section (sigma) and quantum yield (phi) data are more consistent with these experimental measurements than those based upon the currently accepted sigma and phi data.

  13. Modeling anisotropic sensitivity in pentaerythritol tetranitrate using strain rate dependent reactive flow model

    NASA Astrophysics Data System (ADS)

    Kim, Kihong; Fried, Laurence; Yoh, Jack

    2013-06-01

    Initiation of detonation in some high explosives has shown strong anisotropic sensitivity under mechanical impact. Preferred directions of crystal orientation on shock initiation have been experimentally observed in pentaerythritol tetranitrate (PETN), which resulted in dramatic difference in the detonation sensitivity upon shock compression in different directions. The ignition and growth model based on empirical observation on the pressure-dependent initiation of detonation has been widely used to date. Since the model is independent of direction of compression, it is impossible to address sensitivity associated with preferred crystal orientation for establishing the go/no-go criteria. In this paper, we have proposed a new reaction flow model that is consistent with avaialble PETN experiments and atomistic calculations. A general tensor notation is utilized to fully address three-dimensional effect of the strain rate dependence to anisotropic detonation of PETN. K. Kim was supported by post-doctoral research fellowship from the National Research Foundation of Korea.

  14. Thermomechanics-based nonlinear rate-dependent coupled damage-plasticity granular micromechanics model

    NASA Astrophysics Data System (ADS)

    Misra, Anil; Singh, Viraj

    2015-09-01

    Thermomechanics and granular micromechanics approaches are combined to derive constitutive equations for modeling rate-dependent granular materials with damage and plasticity. The derivation is motivated by the recognition that the effect of micro-scale mechanisms upon the macro-scale behavior is known to be significant for granular materials. A general thermomechanical framework applicable to rate-dependent granular materials with damage and plasticity is developed. Based upon this framework, an expression for macro-scale Cauchy stress tensor is obtained in terms of the micro-scale grain interaction forces and the relationship between micro- and macro-scale kinematics. In addition, a Clausius-Duhem type inequality applicable to inter-granular interaction is derived, which is used to establish micro-scale constitutive relations for particular type of inter-granular interactions. The expression for Cauchy stress tensor and the micro-scale constitutive relations is then combined under a mean field kinematic assumption to obtain evolution-type macro-scale constitutive equations. The advantage of the granular micromechanics approach is that the damage and plasticity are defined using simple 1d functions at micro-scale, and complicated plastic potentials, damage functions and rules for their evolution are not required. The resultant model is applied to investigate primary, secondary and tertiary creep, creep-recovery as well as rate-dependent response under uniaxial compressive loading. Model applicability is also demonstrated for asymmetric tensile-compressive response under creep-recovery loading. The model is used to evaluate the evolution of elastic energy, and viscous, plastic and damage dissipation at the macro- and micro-scale with respect to creep time and loading level. The results show the development of loading-induced anisotropy due to damage and plasticity in these materials.

  15. Elevated time-dependent strengthening rates observed in San Andreas Fault drilling samples

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.; Carpenter, Brett M.; Vogt, Christoph; Kopf, Achim J.

    2016-09-01

    The central San Andreas Fault in California is known as a creeping fault, however recent studies have shown that it may be accumulating a slip deficit and thus its seismogenic potential should be seriously considered. We conducted laboratory friction experiments measuring time-dependent frictional strengthening (healing) on fault zone and wall rock samples recovered during drilling at the San Andreas Fault Observatory at Depth (SAFOD), located near the southern edge of the creeping section and in the direct vicinity of three repeating microearthquake clusters. We find that for hold times of up to 3000 s, frictional healing follows a log-linear dependence on hold time and that the healing rate is very low for a sample of the actively shearing fault core, consistent with previous results. However, considering longer hold times up to ∼350,000 s, the healing rate accelerates such that the data for all samples are better described by a power law relation. In general, samples having a higher content of phyllosilicate minerals exhibit low log-linear healing rates, and the notably clay-rich fault zone sample also exhibits strong power-law healing when longer hold times are included. Our data suggest that weak faults, such as the creeping section of the San Andreas Fault, can accumulate interseismic shear stress more rapidly than expected from previous friction data. Using the power-law dependence of frictional healing on hold time, calculations of recurrence interval and stress drop based on our data accurately match observations of discrete creep events and repeating Mw = 2 earthquakes on the San Andreas Fault.

  16. Scaling of Viscous Shear Zones with Depth Dependent Viscosity and Power Law Stress-strain Rate Dependence

    NASA Astrophysics Data System (ADS)

    Moore, J. D. P.; Parsons, B.

    2014-12-01

    One of the unresolved questions concerning fault deformation is the degree and cause of localisation of shear at depth beneath a fault. Geologic observations of exhumed shear zones indicate that whilst the motion is no longer planar, it can still be localised near the down-dip extension of the fault; however, the degree of localisation is uncertain. We employ simple analytic and numerical models to investigate the structural form of distributed shear beneath a strike-slip fault, and the relative importance of the physical mechanisms that have the potential to localise a shear zone. As we are concerned with long-term structure the model is time-averaged across the earthquake cycle, consisting of an idealised strike-slip fault within a rigid lid over a viscous layer. For a depth dependent viscosity, η = η0 exp (-z/z0), we find a shear zone develops with a half-width δw √z0 for small z0, where lengths are non-dimensionalised by the layer thickness (d km). Including a non-linear stress-strain rate relation (ɛ ˙ ∝ σn) scales δw by 1/√n, comparable to deformation length scales in thin viscous sheet calculations. We find that the primary control on δw is the depth dependence of viscosity arising from the increase in temperature with depth. As this relationship is exponential, scaling relations give a half-width that scales approximately as δw≈T(z=1/2)RdnQβ-----√km,delta_wapprox T(z=1/2){sqrtfrac{Rd}{nQbeta}} km, with T (K), gas constant R (J/mol K), activation energy Q (J/mol), and geotherm β (K/km). Figure illustrates shear zones for a dry olivine composition. For n = 1 the shear zone half-width is δw = 4 km, which reduces to δw = 2.3 km when n = 3; other parameter choices consistent with laboratory-derived rheological properties give δwfrom 2-6 km. The inclusion of shear-stress heating only reduces δw by an additional 5-25%, depending on the initial width of the shear zone; in the case of dry olivine with n = 3 we get δw = 1.8 km. This

  17. Flow Rate- and Fracture Property Dependence of Fracture-Matrix Ensemble Relative Permeability

    NASA Astrophysics Data System (ADS)

    Matthai, S. K.; Lang, P.; Bazrafkan, S.

    2012-12-01

    The grid-block scale ensemble relative permeability, kri of fractured porous rock with appreciable matrix permeability is of decisive interest to reservoir simulation and the prediction of production, injector-producer water breakthrough, and ultimate recovery. While the dynamic behaviour of naturally fractured reservoirs (NFR) already provides many clues about (pseudo) kri on the inter-well length scale, such data are difficult to interpret because, in the subsurface, the exact fracture geometry is unknown. Here we present numerical simulation results from discrete fracture and matrix (DFM) unstructured grid hybrid FEM-FVM simulation models, predicting the shape of fracture-matrix kri curves. In contrast to our earlier work, we also simulate capillary fracture matrix transfer (CFMT) and without relying the frequently made simplifying assumption that fracture saturation reflects fracture-matrix capillary pressure equilibrium. We also employ a novel discretization of saturation which permits jump discontinuities to develop across the fracture-matrix interface. This increased physical realism permits - for the first time - to test our earlier semi-analytical model of the flow rate dependence of relative permeability, ensuing from CFMT. The sensitivity analysis presented here constrains CMFT-related flow rate dependence of kri and illustrates how it manifests itself in two geometries of layer-restricted well-developed fracture patterns mapped in the field. We have also investigated the dependence of kri on fracture aperture as computed using discrete element analysis for plausible states of in situ stress. Our results indicate that fracture-matrix ensemble relative permeability can be matched with a new semi-analytic model taking into account the fracture-matrix flux ratio, the wetted fracture-matrix interface area as a function of saturation and the breakthrough saturation. However, we also detect a scale dependence of kri requiring a more elaborate treatment.

  18. The Mitral Valve Prolapsus: Quantification of the Regurgitation Flow Rate by Experimental Time-Dependant PIV

    NASA Astrophysics Data System (ADS)

    Billy, F.; Coisne, D.; Sanchez, L.; Perrault, R.

    2001-10-01

    Color Doppler is routinely used for visualisation of intra cardiac flows and quantification of valvular heart disease, Nevertheless the 2D visualization of a complex 3D phenomenon is the major limitation of this technique, In particular, in clinical setting, the flow rate calculation upstream a regurgitant orifice (i,e, mitral valve insufficiency), assumes that the velocity field in the convergent region have hemispheric shapes and introduce miscalculation specially in case of prolaps regurgitant orifices, The main objective of this study was to characterize the dynamic 3D velocity field of the convergent region upstream a prolaps model of regurgitant orifice based on 2D time dependent PIV reconstruction.

  19. Strong field ionization rates simulated with time-dependent configuration interaction and an absorbing potential

    SciTech Connect

    Krause, Pascal; Sonk, Jason A.; Schlegel, H. Bernhard

    2014-05-07

    Ionization rates of molecules have been modeled with time-dependent configuration interaction simulations using atom centered basis sets and a complex absorbing potential. The simulations agree with accurate grid-based calculations for the ionization of hydrogen atom as a function of field strength and for charge resonance enhanced ionization of H{sub 2}{sup +} as the bond is elongated. Unlike grid-based methods, the present approach can be applied to simulate electron dynamics and ionization in multi-electron polyatomic molecules. Calculations on HCl{sup +} and HCO{sup +} demonstrate that these systems also show charge resonance enhanced ionization as the bonds are stretched.

  20. Size-dependant heating rates of iron oxide nanoparticles for magnetic fluid hyperthermia

    PubMed Central

    Gonzales-Weimuller, Marcela; Zeisberger, Matthias; Krishnan, Kannan M.

    2015-01-01

    Using the thermal decomposition of organometallics method we have synthesized high-quality, iron oxide nanoparticles of tailorable size up to ~15nm and transferred them to a water phase by coating with a biocompatible polymer. The magnetic behavior of these particles was measured and fit to a log-normal distribution using the Chantrell method and their polydispersity was confirmed to be very narrow. By performing calorimetry measurements with these monodisperse particles we have unambiguously demonstrated, for the first time, that at a given frequency, heating rates of superparamagnetic particles are dependent on particle size, in agreement with earlier theoretical predictions. PMID:26405373

  1. Implications of two Holocene time-dependent geomagnetic models for cosmogenic nuclide production rate scaling

    NASA Astrophysics Data System (ADS)

    Lifton, Nathaniel

    2016-01-01

    The geomagnetic field is a major influence on in situ cosmogenic nuclide production rates at a given location (in addition to atmospheric pressure and, to a lesser extent, solar modulation effects). A better understanding of how past fluctuations in these influences affected production rates should allow more accurate application of cosmogenic nuclides. As such, this work explores the cosmogenic nuclide production rate scaling implications of two recent time-dependent spherical harmonic geomagnetic models spanning the Holocene. Korte and Constable (2011, Phys. Earth Planet. Inter.188, 247-259) and Korte et al. (2011, Earth Planet. Sci. Lett. 312, 497-505) recently updated earlier spherical harmonic paleomagnetic models with new paleomagnetic data from sediment cores in addition to new archeomagnetic and volcanic data. These updated models offer improved resolution and accuracy over the previous versions, in part due to increased temporal and spatial data coverage. In addition, Pavón-Carrasco et al. (2014, Earth Planet. Sci. Lett. 388, 98-109) developed another time-dependent spherical harmonic model of the Holocene geomagnetic field, based solely on archeomagnetic and volcanic paleomagnetic data from the same underlying paleomagnetic database as the Korte et al. models, but extending to 14 ka. With the new models as input, trajectory-traced estimates of effective vertical cutoff rigidity (RC - the standard method for ordering cosmic ray data) yield significantly different time-integrated scaling predictions when compared to each other and to results using the earlier models. In addition, predictions of each new model using RC are tested empirically using recently published production rate calibration data for both 10Be and 3He, and compared to predictions using corresponding time-varying geocentric dipolar RC formulations and a static geocentric axial dipole (GAD) model. Results for the few calibration sites from geomagnetically sensitive regions suggest that the

  2. Rate dependent response and failure of a ductile epoxy and carbon fiber reinforced epoxy composite

    SciTech Connect

    Brown, Eric N; Rae, Philip J; Dattelbaum, Dana M; Stahl, David B

    2010-01-01

    An extensive characterization suite has been performed on the response and failure of a ductile epoxy 55A and uniaxial carbon fiber reinforced epoxy composite of IM7 fibers in 55A resin from the quasistatic to shock regime. The quasistatic and intermediate strain rate response, including elastic modulus, yield and failure have are characterized by quasistatic, SHPB, and DMA measurements as a function of fiber orientation and temperature. The high strain rate shock effect of fiber orientation in the composite and response of the pure resin are presented for plate impact experiments. It has previously been shown that at lower impact velocities the shock velocity is strongly dependent on fiber orientation but at higher impact velocity the in-plane and through thickness Hugoniots converge. The current results are compared with previous studies of the shock response of carbon fiber composites with more conventional brittle epoxy matrices. The spall response of the composite is measured and compared with quasistatic fracture toughness measurements.

  3. Xylem cavitation resistance can be estimated based on time-dependent rate of acoustic emissions.

    PubMed

    Nolf, Markus; Beikircher, Barbara; Rosner, Sabine; Nolf, Anton; Mayr, Stefan

    2015-10-01

    Acoustic emission (AE) analysis allows nondestructive monitoring of embolism formation in plant xylem, but signal interpretation and agreement of acoustically measured hydraulic vulnerability with reference hydraulic techniques remain under debate. We compared the hydraulic vulnerability of 16 species and three crop tree cultivars using hydraulic flow measurements and acoustic emission monitoring, proposing the use of time-dependent AE rates as a novel parameter for AE analysis. There was a linear correlation between the water potential (Ψ) at 50% loss of hydraulic conductivity (P50 ) and the Ψ at maximum AE activity (Pmaxrate ), where species with lower P50 also had lower Pmaxrate (P < 0.001, R(2)  = 0.76). Using AE rates instead of cumulative counts for AE analysis allows more efficient estimation of P50 , while excluding problematic AE at late stages of dehydration. PMID:26010417

  4. Effects of freshwater petroleum contamination on amphibian hatching and metamorphosis

    SciTech Connect

    Mahaney, P.A. . Dept. of Zoology)

    1994-02-01

    This study examined the effects of freshwater petroleum contamination on amphibian reproduction. The primary objectives were to assess the potential environmental and physiological impacts of runoff petroleum products on amphibians, using the green tree frog (Hyla cinerea) as a target species and engine crankcase oil as a contaminant. Egg hatching success, tadpole growth, and successful metamorphosis were measured in four concentrations of oil. The effects of oil on food source was also studied. Hatching success was not measurably influenced by the presence of oil. Tadpole and alga growth were negatively associated with the presence of oil. No tadpoles from the high concentration of oil treatments successfully metamorphosed.

  5. Shear Rate Dependence of the Pāhoehoe to `A`ā Transition

    NASA Astrophysics Data System (ADS)

    Soule, A.; Cashman, K.

    2003-12-01

    The surface morphology transition from pāhoehoe-to-`a`ā on basaltic lava flows can be used to interpret the emplacement conditions of solidified flows and predict the behavior of active flows. Investigations of this phenomenon have emphasized either the mechanical properties of the solidified crust (e.g., Kilburn, 1981), or the rheologic properties of the liquid interior (e.g., Peterson and Tilling, 1980). In the latter, the boundary separating pāhoehoe and `a`ā is represented qualitatively by an inverse relationship between apparent viscosity and shear rate. Recent investigations of the rheology dependence of the transition have revealed a critical crystallinity range at which pāhoehoe transforms to `a`ā of φ = 0.18 to 0.35 that can vary between flows. Here, we extend this approach to investigate the shear rate dependence of the pāhoehoe-to-`a`ā transition. We use a suspension of corn syrup and rice to represent lava with crystals. Suspensions of varying particle concentration (φ = 0.15 to 0.40) are sheared in a Couette rheometer over a range of constant shear rates (0.1 to 2.0 s-1). We describe three deformation regimes, clumping, shear zone formation, and fluid failure that produce changes in the suspension microstructure and lead to shear localization. The deformation mechanisms are imaged with digital video and quantified by tracking individual particle paths. In the presence of cooling, these shear localization may be the mechanism by which `a`ā flow surfaces form. We find that the onset of each regime follows the expected inverse relationship between shear rate and suspension viscosity. We expect that the results of these experiments apply to the thermal boundary layer of a flow and thus bridge the distinct approaches taken to investigate this phenomenon. The results of these experiments can contribute to more detailed lava flow modeling and better assessment of flow dynamics from solidified lava flows.

  6. Material Properties and Plasma Display Panel Discharging Characteristics Depending on MgO Evaporation Rate

    NASA Astrophysics Data System (ADS)

    Kwon, Sang Jik; Kim, Yong Jae; Lee, Seong Eui

    2006-11-01

    MgO thin film is most widely used as a protecting layer in ac Plasma Display Panel. The film is deposited using electron beam evaporation. The effects of the evaporation rate of MgO film deposited using an electron beam on the MgO properties and the discharge characteristics of the plasma display panel (PDP) were investigated. The evaporation rate was changed from 3 to 15 Å/s at a substrate temperature of 300 °C. MgO properties such as crystal orientation, surface roughness, contact angle, and film structure were inspected using X-ray diffraction (XRD), analysis atomic force microscopy (AFM), drop shape analysis, and secondary electron microscopy (SEM). The MgO properties were shown to be strongly dependent on the evaporation rate. We also studied the relation between MgO properties and PDP discharging characteristics. The minimum firing voltage and maximum luminous efficiency were obtained at an evaporation rate of 5 Å/s. In the MgO film deposited at 5 Å/s, the (200) orientation was most intensive and surface roughness was minimum.

  7. A new rate-dependent unidirectional composite model - Application to panels subjected to underwater blast

    NASA Astrophysics Data System (ADS)

    Wei, Xiaoding; de Vaucorbeil, Alban; Tran, Phuong; Espinosa, Horacio D.

    2013-06-01

    In this study, we developed a finite element fluid-structure interaction model to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. A new failure criterion that includes strain-rate effects was formulated and implemented to simulate different damage modes in unidirectional glass fiber/matrix composites. The laminate model uses Hashin's fiber failure criterion and a modified Tsai-Wu matrix failure criterion. The composite moduli are degraded using five damage variables, which are updated in the post-failure regime by means of a linear softening law governed by an energy release criterion. A key feature in the formulation is the distinction between fiber rupture and pull-out by introducing a modified fracture toughness, which varies from a fiber tensile toughness to a matrix tensile toughness as a function of the ratio of longitudinal normal stress to effective shear stress. The delamination between laminas is modeled by a strain-rate sensitive cohesive law. In the case of sandwich panels, core compaction is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. These constitutive descriptions were used to predict deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, for both monolithic and sandwich composite panels subjected to underwater blast. The numerical predictions were compared with experimental observations. We demonstrate that the new rate dependent composite damage model captures the spatial distribution and magnitude of damage significantly more accurately than previously developed models.

  8. High Precision Measurements of Temperature Dependence of Creep Rate of Polycrystalline Forsterite

    NASA Astrophysics Data System (ADS)

    Nakakoji, T.; Hiraga, T.

    2014-12-01

    Obtaining temperature dependence of creep rate, that is, activation energy for the creep is critical in geophysics, since its value can indicate deformation mechanism and also allows to extrapolate the creep rate measured in the room experiments to geological conditions when the creep mechanism is identical in both cases. Although numerous experimental results have been obtained so far, the obtained activation energy often contains error range of >50 kJ/mol, which often causes large uncertainties in strain rate at applied geological conditions. To minimize this error, it is important to collect strain rates at many different temperatures with high accuracy. We conducted high temperature compression experiments on synthetic forsterite (90%vol) and enstatite (10vol %) aggregates under increasing and decreasing temperatures. We applied a constant load of ~20 MPa using uniaxial testing machine (Shimadzu AG-X 50kN). The temperature was changed from 1360°C to 1240°C by furnace attached to the machine. Prior to the applying the load to the samples the grain size was saturated at 1360°C for 24 hours to minimize grain growth during the test. Decreasing-rate of temperature was 0.11min/°C and 0.02min/°C at temperature ranges of 1360 to 1300 and 1300 to 1240 respectively. The increasing-rate of the temperature was the same as the decreasing-rate. Strain rates from every 1 degree were obtained successfully. After the experiment, we analyzed the microstructure of the sample with scanning electron microscopy to measure the grain diameter. Arrhenius plots of strain rate demonstrate very linear distribution at > 1300 °C giving an activation energy of 649 ± 14 kJ/mol, whereas weak transition to lower activation energy 550 ± 23 kJ/mol below 1300°C was observed. Tasaka et al. (2013) obtained the activation energy of 370 ± 50 kJ/mol from similar temperature ranges used in our study but finer-grained samples. Combining these results, we interpret our results of high activation

  9. Regression Splines in the Time-Dependent Coefficient Rates Model for Recurrent Event Data

    PubMed Central

    Amorim, Leila D.; Cai, Jianwen; Zeng, Donglin; Barreto, Maurício L.

    2009-01-01

    SUMMARY Many epidemiologic studies involve the occurrence of recurrent events and much attention has been given for the development of modelling techniques that take into account the dependence structure of multiple event data. This paper presents a time-dependent coefficient rates model that incorporates regression splines in its estimation procedure. Such method would be appropriate in situations where the effect of an exposure or covariates changes over time in recurrent event data settings. The finite sample properties of the estimators are studied via simulation. Using data from a randomized community trial that was designed to evaluate the effect of vitamin A supplementation on recurrent diarrheal episodes in small children, we model the functional form of the treatment effect on the time to the occurrence of diarrhea. The results describe how this effect varies over time. In summary, we observed a major impact of the vitamin A supplementation on diarrhea after 2 months of the dosage, with the effect diminishing after the third dosage. The proposed method can be viewed as a flexible alternative to the marginal rates model with constant effect in situations where the effect of interest may vary over time. PMID:18696748

  10. Endogenous and exogenous estrogens during embryonic development affect timing of hatch and growth in the American alligator (Alligator mississippiensis).

    PubMed

    Cruze, Lori; Roark, Alison M; Rolland, Gabrielle; Younas, Mona; Stacy, Nicole; Guillette, Louis J

    2015-06-01

    Prenatal exposure to estrogenic endocrine disrupting chemicals (EDCs) can affect length of gestation and body mass and size of offspring. However, the dose, timing, and duration of exposure as well as sex and strain of the experimental animals determine the direction and magnitude of these effects. In this study, we examined the effects of a one-time embryonic exposure to either 17 β-estradiol (E2) or bisphenol A (BPA) on rate of development and growth in American alligators (Alligator mississippiensis). Our results indicate that BPA and E2-treated alligators hatched approximately 1.4 days earlier than vehicle-treated (control) alligators, suggesting that estrogenic chemicals hasten hatching in these animals. We assessed growth rates, growth allometry, and body condition for 21 weeks after hatching and found that BPA-treated alligators grew more quickly shortly after hatching but more slowly thereafter compared to control alligators. Conversely, E2-treated alligators grew more slowly shortly after hatching but more quickly thereafter compared to control alligators. As a result of differences in growth rate, BPA-treated alligators were heavier, longer, and fatter than control alligators at age 5 weeks but were similar in size and leaner than control alligators at age 21 weeks. Biochemical analytes were examined at the end of the 21-week study to assess overall metabolic condition. We found that E2-treated alligators had significantly higher circulating plasma concentrations of cholesterol and triglycerides than control alligators while BPA-treated alligators had blood profiles comparable to control alligators. Our results provide important insights into the effects of exogenous estrogens on morphology and metabolism in an oviparous, semi-aquatic reptile. PMID:25687799

  11. Pre-hatching fluoxetine-induced neurochemical, neurodevelopmental, and immunological changes in newly hatched cuttlefish.

    PubMed

    Bidel, Flavie; Di Poi, Carole; Imarazene, Boudjema; Koueta, Noussithé; Budzinski, Hélène; Van Delft, Pierre; Bellanger, Cécile; Jozet-Alves, Christelle

    2016-03-01

    Embryonic and early postembryonic development of the cuttlefish Sepia officinalis (a cephalopod mollusk) occurs in coastal waters, an environment subject to considerable pressure from xenobiotic pollutants such as pharmaceutical residues. Given the role of serotonin in brain development and its interaction with neurodevelopmental functions, this study focused on fluoxetine (FLX), a selective serotonin reuptake inhibitor (SSRI, antidepressant). The goal was to determine the effects of subchronic waterborne FLX exposure (1 and 10 μg L(-1)) during the last 15 days of embryonic development on neurochemical, neurodevelopmental, behavioral, and immunological endpoints at hatching. Our results showed for the first time that organic contaminants, such as FLX, could pass through the eggshell during embryonic development, leading to a substantial accumulation of this molecule in hatchlings. We also found that FLX embryonic exposure (1 and 10 μg L(-1)) (1) modulated dopaminergic but not serotonergic neurotransmission, (2) decreased cell proliferation in key brain structures for cognitive and visual processing, (3) did not induce a conspicuous change in camouflage quality, and (4) decreased lysozyme activity. In the long term, these alterations observed during a critical period of development may impair complex behaviors of the juvenile cuttlefish and thus lead to a decrease in their survival. Finally, we suggest a different mode of action by FLX between vertebrate and non-vertebrate species and raise questions regarding the vulnerability of early life stages of cuttlefish to the pharmaceutical contamination found in coastal waters. PMID:25966880

  12. Dependence of rates of breakage on fines content in wet ball mill grinding

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Anirban

    The following research fundamentally deals with the cause and implications of nonlinearities in breakage rates of materials in wet grinding systems. The innate dependence of such nonlinearities on fines content and the milling environment during wet grinding operations is also tested and observed. Preferential breakage of coarser size fractions as compared to the finer size fractions in a particle population were observed and discussed. The classification action of the pulp was deemed to be the probable cause for such a peculiarity. Ores with varying degrees of hardness and brittleness were used for wet grinding experiments, primarily to test the variations in specific breakage rates as a function of varying hardness. For this research, limestone, quartzite, and gold ore were used. The degree of hardness is of the order of: limestone, quartzite, gold ore. Selection and breakage function parameters were determined in the course of this research. Functional forms of these expressions were used to compare experimentally derived parameter estimates. Force-fitting of parameters was not done in order to examine the realtime behavior of particle populations in wet grinding systems. Breakage functions were established as being invariant with respect to such operating variables like ball load, mill speed, particle load, and particle size distribution of the mill. It was also determined that specific selection functions were inherently dependent on the particle size distribution in wet grinding systems. Also, they were consistent with inputs of specific energy, according to grind time. Nonlinearity trends were observed for 1st order specific selection functions which illustrated variations in breakage rates with incremental inputs of grind time and specific energy. A mean particle size called the fulcrum was noted below which the nonlinearities in the breakage trends were observed. This magnitude of the fulcrum value varied with percent solids and slurry filling, indicating

  13. Impact of Daily Thermocycles on Hatching Rhythms, Larval Performance and Sex Differentiation of Zebrafish

    PubMed Central

    Villamizar, Natalia; Ribas, Laia; Piferrer, Francesc; Vera, Luisa M.; Sánchez-Vázquez, Francisco Javier

    2012-01-01

    In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled “gating” mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation. PMID:23284912

  14. Mathematical equivalence between time-dependent single-rate and multirate mass transfer models

    NASA Astrophysics Data System (ADS)

    Fernández-Garcia, D.; Sanchez-Vila, X.

    2015-05-01

    The often observed tailing of tracer breakthrough curves is caused by a multitude of mass transfer processes taking place over multiple scales. Yet, in some cases, it is convenient to fit a transport model with a single-rate mass transfer coefficient that lumps all the non-Fickian observed behavior. Since mass transfer processes take place at all characteristic times, the single-rate mass transfer coefficient derived from measurements in the laboratory or in the field vary with time ω>(t>). The literature review and tracer experiments compiled by Haggerty et al. (2004) from a number of sites worldwide suggest that the characteristic mass transfer time, which is proportional to ω>(t>)-1, scales as a power law of the advective and experiment duration. This paper studies the mathematical equivalence between the multirate mass transfer model (MRMT) and a time-dependent single-rate mass transfer model (t-SRMT). In doing this, we provide new insights into the previously observed scale-dependence of mass transfer coefficients. The memory function, g(t), which is the most salient feature of the MRMT model, determines the influence of the past values of concentrations on its present state. We found that the t-SRMT model can also be expressed by means of a memory function φ>(t,τ>). In this case, though the memory function is nonstationary, meaning that in general it cannot be written as φ>(t-τ>). Nevertheless, the full behavior of the concentrations using a single time-dependent rate ω>(t>) is approximately analogous to that of the MRMT model provided that the equality ω>(t>)=-dln⁡g>(t>)/dt holds and the field capacity is properly chosen. This relationship suggests that when the memory function is a power law, g>(t>)˜t1-k, the equivalent mass transfer coefficient scales as ω>(t>)˜t-1, nicely fitting without calibration the estimated mass transfer coefficients compiled by Haggerty et al. (2004).

  15. Reinforcement Magnitude Modulates the Rate-Dependent Effects of Fluvoxamine and Desipramine on Fixed-Interval Responding in the Pigeon

    PubMed Central

    Lamb, R.J.; Ginsburg, Brett C.

    2013-01-01

    Some doses of fluvoxamine can decrease ethanol-maintained behavior more than food-maintained behavior. This might be explained by differences in reinforcement magnitude. In a previous study, fluvoxamine’s effects on Fixed-Ratio responding did not depend upon reinforcement magnitude. However, response rates differed with reinforcement magnitude. These differences in response rate might explain the failure to observe differences in the potency of fluvoxamine with changes in reinforcement magnitude. Methods We examined if the effects of fluvoxamine and desipramine depend on reinforcement magnitude and response rate by administering these drugs to pigeons responding under a multiple Fixed-Interval schedule in which responding in three components was maintained by differing durations of food presentation (2-, 4-, & 8-sec). Results Fluvoxamine and desipramine’s effects depended jointly on control rate, reinforcement magnitude, and dose. Low fluvoxamine doses had rate-dependent effects in all three components, --increasing lower rates more than higher rates; as dose increased these rate-dependent effects became greater for components maintained by 2- or 4-sec of food presentation, while declining in the component maintained by 8-sec. Low desipramine doses had rate-dependent effects only in the component maintained by 2-sec; whereas higher doses had rate-dependent effects in components maintained by 2- or 4-sec. Still higher doses had rate-dependent effects in all three components. Conclusions While the effects of fluvoxamine and desipramine may not depend upon reinforcement magnitude when studied under Fixed-Ratio schedules, reinforcement magnitude can modulate their effects when studied over a wider range of control response rates. PMID:18195594

  16. A biophysically-based neuromorphic model of spike rate- and timing-dependent plasticity.

    PubMed

    Rachmuth, Guy; Shouval, Harel Z; Bear, Mark F; Poon, Chi-Sang

    2011-12-01

    Current advances in neuromorphic engineering have made it possible to emulate complex neuronal ion channel and intracellular ionic dynamics in real time using highly compact and power-efficient complementary metal-oxide-semiconductor (CMOS) analog very-large-scale-integrated circuit technology. Recently, there has been growing interest in the neuromorphic emulation of the spike-timing-dependent plasticity (STDP) Hebbian learning rule by phenomenological modeling using CMOS, memristor or other analog devices. Here, we propose a CMOS circuit implementation of a biophysically grounded neuromorphic (iono-neuromorphic) model of synaptic plasticity that is capable of capturing both the spike rate-dependent plasticity (SRDP, of the Bienenstock-Cooper-Munro or BCM type) and STDP rules. The iono-neuromorphic model reproduces bidirectional synaptic changes with NMDA receptor-dependent and intracellular calcium-mediated long-term potentiation or long-term depression assuming retrograde endocannabinoid signaling as a second coincidence detector. Changes in excitatory or inhibitory synaptic weights are registered and stored in a nonvolatile and compact digital format analogous to the discrete insertion and removal of AMPA or GABA receptor channels. The versatile Hebbian synapse device is applicable to a variety of neuroprosthesis, brain-machine interface, neurorobotics, neuromimetic computation, machine learning, and neural-inspired adaptive control problems. PMID:22089232

  17. Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities

    SciTech Connect

    Wang, Lifan; Strovink, Mark; Conley, Alexander; Goldhaber,Gerson; Kowalski, Marek; Perlmutter, Saul; Siegrist, James

    2005-12-14

    Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least an equal share likely belongs to B{sub BV}. SN magnitudes measured using maximum-luminosity or cmagic methods show comparable rms deviations of order {approx}0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km s{sup -1} on the rms peculiar velocity of nearby SNe relative to the Hubble flow.

  18. Effects of Vocational Consultation on Relapse Rate and Hope among Drug Dependents in Bojnurd, Iran

    PubMed Central

    Hojjat, Seyed Kaveh; Raufpoor, Roghieh; Khalili, Mina Norozi; Hamidi, Mahin; Danesh, Mahsa; Ziarat, Hadiseh Monadi

    2016-01-01

    Introduction Drug addiction is one of the most flagrant social damages that can easily enervate the socio-cultural foundation of a country as well as endanger human dynamism. One of the prevalent problems among most addicted people is their low hope and relapse of drug dependence. The aim of this study was to assess the effect of vocational consultation (for training on problem-solving skills) on hope and relapse rate of patients treated in methadone maintenance clinics. Methods This experiment was conducted on 60 drug abusers treated in a methadone maintenance program in drug addiction centers in Bojnurd, Iran, in 2014. The patients were randomly and equally allocated into two study and control groups. All patients completed the Miller Hope Questionnaire before and after the intervention. Ten sessions of vocational consultation were held for the study group while the control group received no special treatment. Patients were followed up on for relapses for six months. Data were analyzed using SPSS (version 16) and the paired-samples t-test technique. Results The results indicated that the mean and standard deviation of hope on the pre-test in the study group increased on the post-test (from M=175.5, SD=31.8, to M=198.5, SD=20.4), while in the control group the mean of hope decreased from the pre-test to past-test stage (M=184.7, SD=27.7, to M=183.3, SD=26.1), showing a significant relationship, t(56)= 5.657, p<0.05. The relapse rate was not significantly different in the two groups. Conclusion The vocational consultation positively affects hope among drug dependents but did not affect their relapse rate during the six-month follow-up. Increasing the hope in these groups of patients may be effective in other aspects of treatment success in long-term follow-up. PMID:26955440

  19. Functional characterization of normal and degraded bovine meniscus: rate-dependent indentation and friction studies.

    PubMed

    Baro, Vincent J; Bonnevie, Edward D; Lai, Xiaohan; Price, Christopher; Burris, David L; Wang, Liyun

    2012-08-01

    The menisci are known to play important roles in normal joint function and the development of diseases such as osteoarthritis. However, our understanding of meniscus' load bearing and lubrication properties at the tissue level remains limited. The objective of this investigation was to characterize the site- and rate-dependency of the compressive and frictional responses of the meniscus under a spherical contact load. Using a custom testing device, indentation tests with rates of 1, 10, 25, 50, and 100μm/s were performed on bovine medial meniscus explants, which were harvested from five locations including the femoral apposing surface at the anterior, central, and posterior locations and the central portion at the deep layer and at the tibial apposing surface (n=5 per location). Sliding tests with rates of 0.05, 0.25, 1, and 5mm/s were performed on the central femoral aspect and central tibial aspect superficial samples (n=6 per location). A separate set of superficial samples were subjected to papain digestion and tested prior to and post treatment. Our findings are: i) the Hertz contact model can be used to fit the force responses of meniscus under the conditions tested; ii) the anterior region is significantly stiffer than the posterior region and tissue modulus does not vary with tissue depth at the central region; iii) the friction coefficient of the meniscus is on the order of 0.02 under migratory contacts and the femoral apposing surface tends to show lower friction than the tibial apposing surface; iv) the meniscus exhibits increased modulus and lubrication with increased indentation and sliding rates; v) matrix degradation impedes the functional load support and lubrication properties of the tissue. The site- and rate-dependent properties of the meniscus may be attributed to spatial variations of the tissue's biphasic structure. These properties substantiate the role of the meniscus as one of the important bearing surfaces of the knee. These data

  20. Timing and Variability of Galactose Metabolic Gene Activation Depend on the Rate of Environmental Change

    PubMed Central

    Ma, Bo; Ott, William; Josić, Krešimir; Bennett, Matthew R.

    2015-01-01

    Modulation of gene network activity allows cells to respond to changes in environmental conditions. For example, the galactose utilization network in Saccharomyces cerevisiae is activated by the presence of galactose but repressed by glucose. If both sugars are present, the yeast will first metabolize glucose, depleting it from the extracellular environment. Upon depletion of glucose, the genes encoding galactose metabolic proteins will activate. Here, we show that the rate at which glucose levels are depleted determines the timing and variability of galactose gene activation. Paradoxically, we find that Gal1p, an enzyme needed for galactose metabolism, accumulates more quickly if glucose is depleted slowly rather than taken away quickly. Furthermore, the variability of induction times in individual cells depends non-monotonically on the rate of glucose depletion and exhibits a minimum at intermediate depletion rates. Our mathematical modeling suggests that the dynamics of the metabolic transition from glucose to galactose are responsible for the variability in galactose gene activation. These findings demonstrate that environmental dynamics can determine the phenotypic outcome at both the single-cell and population levels. PMID:26200924

  1. The rate dependent response of a bistable chain at finite temperature

    NASA Astrophysics Data System (ADS)

    Benichou, Itamar; Zhang, Yaojun; Dudko, Olga K.; Givli, Sefi

    2016-10-01

    We study the rate dependent response of a bistable chain subjected to thermal fluctuations. The study is motivated by the fact that the behavior of this model system is prototypical to a wide range of nonlinear processes in materials physics, biology and chemistry. To account for the stochastic nature of the system response, we formulate a set of governing equations for the evolution of the probability density of meta-stable configurations. Based on this approach, we calculate the behavior for a wide range of parametric values, such as rate, temperature, overall stiffness, and number of elements in the chain. Our results suggest that fundamental characteristics of the response, such as average transition stress and hysteresis, can be captured by a simple law which folds the influence of all these factors into a single non-dimensional quantity. We also show that the applicability of analytical results previously obtained for single-well systems can be extended to systems having multiple wells by proper definition of rate and of the transition stress.

  2. Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure

    NASA Astrophysics Data System (ADS)

    Ryltsev, R. E.; Klumov, B. A.; Chtchelkatchev, N. M.; Shunyaev, K. Yu.

    2016-07-01

    Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ṡ 109, 1013) K/s. Investigating short- and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 ṡ 109 K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at γmin.

  3. A one-dimensional strain-rate-dependent constitutive model for superelastic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Ren, Wenjie; Li, Hongnan; Song, Gangbing

    2007-02-01

    Recently, there is increasing interest in using superelastic shape memory alloys (SMAs) in civil, mechanical and aerospace engineering, attributed to their large recoverable strain range (up to 6-8%), high damping capacity, and excellent fatigue property. In this research, an improved Graesser's model is proposed to model the strain-rate-dependent hysteretic behavior of superelastic SMA wires. Cyclic loading tests of superelastic SMA wires are first performed to determine their hysteresis properties. The effects of the strain amplitude and the loading rate on the mechanical properties are studied and formulated using the least-square method. Based on Graesser's model, an improved model is developed. The improved model divides the full loop into three parts: the loading branch, the unloading branch before the completion of the reverse transformation and the elastic unloading branch after the completion of reverse transformation, where each part adopts its respective parameters. Numerical simulations are conducted using both the original and the improved Graesser's models. Comparisons indicate that the improved Graesser's model accurately reflects the hysteresis characteristics and provides a better prediction of the SMAs' actual hysteresis behavior than the original Graesser's model at varying levels of strain and loading rate.

  4. Rate- and Temperature-Dependent Material Behavior of a Multilayer Polymer Battery Separator

    NASA Astrophysics Data System (ADS)

    Avdeev, Ilya; Martinsen, Michael; Francis, Alex

    2014-01-01

    Designing battery packs for safety in automotive applications requires multiscale modeling, as macroscopic deformations due to impact cause the mechanical failure of individual cells on a sub-millimeter level. The separator material plays a critical role in this process, as the thinning or perforating of the separator can lead to thermal runaway and catastrophic failure of an entire battery pack. The electrochemical properties of various polymer separators have been extensively investigated; however, the dependency of mechanical properties of these thin films on various factors, such as high temperature and strain rate, has not been sufficiently characterized. In this study, the macroscopic mechanical properties of a multilayer polymer thin film used as a battery separator are studied experimentally at various temperatures, strain rates, and solvent saturations. Due to the anisotropy of the material, material testing was conducted in two perpendicular directions (machine and transverse directions). Material samples were tested in both dry and saturated conditions at several temperatures, and it was found that temperature and strain rate have a nearly linear effect on the stress experienced by the material. Additionally, saturating the separator material in a common lithium-ion solvent had softened it and had a positive effect on its toughness. The experimental results obtained in this study can be used to develop mathematical constitutive models of the multilayer separator material for subsequent numerical simulations and design.

  5. Cooling rate dependence of simulated Cu64.5Zr35.5 metallic glass structure.

    PubMed

    Ryltsev, R E; Klumov, B A; Chtchelkatchev, N M; Shunyaev, K Yu

    2016-07-21

    Using molecular dynamics simulations with embedded atom model potential, we study structural evolution of Cu64.5Zr35.5 alloy during the cooling in a wide range of cooling rates γ ∈ (1.5 ⋅ 10(9), 10(13)) K/s. Investigating short- and medium-range orders, we show that the structure of Cu64.5Zr35.5 metallic glass essentially depends on cooling rate. In particular, a decrease of the cooling rate leads to an increase of abundances of both the icosahedral-like clusters and Frank-Kasper Z16 polyhedra. The amounts of these clusters in the glassy state drastically increase at the γmin = 1.5 ⋅ 10(9) K/s. Analysing the structure of the glass at γmin, we observe the formation of nano-sized crystalline grain of Cu2Zr intermetallic compound with the structure of Cu2Mg Laves phase. The structure of this compound is isomorphous with that for Cu5Zr intermetallic compound. Both crystal lattices consist of two types of clusters: Cu-centered 13-atom icosahedral-like cluster and Zr-centered 17-atom Frank-Kasper polyhedron Z16. That suggests the same structural motifs for the metallic glass and intermetallic compounds of Cu-Zr system and explains the drastic increase of the abundances of these clusters observed at γmin. PMID:27448895

  6. Strain rate dependent calcite microfabric evolution - an experiment carried out by nature

    NASA Astrophysics Data System (ADS)

    Rogowitz, Anna; Grasemann, Bernhard; Rice, A. Hugh N.; Huet, Benjamin; Habler, Gerlinde

    2013-04-01

    can be observed in the dislocation creep regime. Textures and the degree of intracrystalline deformation have been measured by electron back scattered diffraction (EBSD). While the host-rock grains do not show any significant crystallographic preferred orientation (CPO), those within the CE show a clear preferred orientation of both the c- and a-axes. Depending on the degree of recrystallization, the orientation of the c-axis changes from oblique to perpendicular to the CE-boundary while the a-axes begin to form a girdle within the CE-boundary. The results of this study will be compared with experimental data, closing the gap between experimental and natural geological strain rates.

  7. Strain-rate Dependence of Power-law Creep and Folding of Rocks

    NASA Astrophysics Data System (ADS)

    Ord, A.; Hobbs, B. E.

    2011-12-01

    Kocks (1987) proposed how the kinetics of deformation associated with different stress levels results in different shear stress-shear strain rate behaviours, with a cross-over or threshold from thermally activated dislocation motion at low stresses to viscous glide at some critical shear stress. Cordier (pers. comm.; Carrez et al., 2010) clarified this transition at least for MgO through atomistic, single dislocation and Dislocation Dynamics calculations. These studies indicate that the power-law relations observed experimentally for deforming rocks may be different for geological strain-rates, in that rate laws may become relatively strain-rate insensitive at low strain-rates. This transition from power law behaviour with relatively small values of the stress exponent, N, (N = 1 to 5) to large values of N (N = 5 to 20) has important implications for the development of localised behaviour during deformation as has been demonstrated at the other end of the spectrum for high stresses by Schmalholz and Fletcher (2011). Since localisation of fold systems arises from softening of the tangential viscosity, large values of N mean that little softening occurs with changes in strain rate, and sinusoidal folds are expected. There is therefore a critical range of N-values where localised, natural looking, folds develop. We explore the implications for folding of linear viscous single layers embedded in power-law viscous materials with N that varies with the stress level. The strain-rate dependence of the power law parameters results in strongly localised, aperiodic folding as opposed to the fold styles that arise from the linear Biot theory of folding. Also developed are axial plane shear fabrics. These structures resemble natural ones more than those that arise from simple Newtonian viscous or power-law behaviour with constant N. The results show that new studies of folded rocks and associated axial plane structures in the field may give important information on the

  8. 11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH DOOR INTO WINCH ROOM IN THE SUPERSTRUCTURE (LABELED AS FASSAGE & HYDRAULIC MACHINERY ON PLAN), SHOWING UNDERSIDE OF GEARED WHEEL OF BOOM. - U.S. Coast Guard Cutter WHITE LUPINE, U.S. Coast Guard Station Rockland, east end of Tillson Avenue, Rockland, Knox County, ME

  9. 45 CFR 1226.10 - Hatch Act restrictions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., directly or indirectly, actively participate in political management or in political campaigns. All... letter or article, signed or unsigned, soliciting votes in favor of or in opposition to any political... 45 Public Welfare 4 2010-10-01 2010-10-01 false Hatch Act restrictions. 1226.10 Section...

  10. 6. Detail of forward fuselage showing open cockpit hatch and ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Detail of forward fuselage showing open cockpit hatch and ladder. View to southeast. - Offutt Air Force Base, Looking Glass Airborne Command Post, Looking Glass Aircraft, On Operational Apron covering northeast half of Project Looking Glass Historic District, Bellevue, Sarpy County, NE

  11. 11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH DOOR INTO WINCH ROOM IN THE SUPERSTRUCTURE (LABELED AT PASSAGE & HYDRAULIC MACHINERY ON PLAN). - U.S. Coast Guard Cutter WHITE HEATH, USGS Integrated Support Command Boston, 427 Commercial Street, Boston, Suffolk County, MA

  12. DETAIL OF MISSILE TUBE HATCH WITH MILLED FITTINGS AT GROUND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF MISSILE TUBE HATCH WITH MILLED FITTINGS AT GROUND FLOOR LEVEL. VIEW FACING EAST - U.S. Naval Base, Pearl Harbor, Ford Island Polaris Missile Lab & U.S. Fleet Ballistic Missile Submarine Training Center, Between Lexington Boulvevard and the sea plane ramps on the southwest side of Ford Island, Pearl City, Honolulu County, HI

  13. Application of Imaging Technology to Chicken Carcasses and Hatching Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Machine vision technology has been utilized by many sectors of the food and agriculture industry to facilitate sorting, inspection, and field mapping. A specific application, hyperspectral imaging, has been adapted to detect the fertility/early development of hatching eggs and fecal material on chi...

  14. TREATING EGGS WITH HYDROGEN PEROXIDE CAN IMPROVE HATCHING SUCCESS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fungal and bacterial egg infections remain a significant problem for hatcheries, greatly reducing hatching success. Chemical therapeutics such as formalin are often used to control potential infections. Although formalin is an effective therapeutic, concerns of safety exist among users due to its ...

  15. HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF PLENUM WITH ATTACHED DRAFT REGULATOR. - Hot Springs National Park, Bathhouse Row, Superior Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

  16. Astronaut Scott Parazynski in hatch of CCT during training

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Astronaut Scott E. Parazynski, STS-66 mission specialist, poses at the hatch of the crew compartment trainer (CCT) prior to a rehearsal of launch and entry procedures for a November 1994 flight aboard the Space Shuttle Atlantis. Parazynski is wearing his launch and entry suit for this training session.

  17. PLAN SECTIONS AND DETAILS OF CELL HATCHES MAIN PROCESSING BUILDING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PLAN SECTIONS AND DETAILS OF CELL HATCHES MAIN PROCESSING BUILDING (CPP-601). INL DRAWING NUMBER 200-0601-00-291-103256. ALTERNATE ID NUMBER 542-11-F-302. - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  18. 3. VIEW OF WATER TANKS FROM ACCESS ROAD TO HATCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW OF WATER TANKS FROM ACCESS ROAD TO HATCH ADIT. VIEW NORTH. LUCKY TIGER MILL OFFICE (FEATURE B-I) IN DISTANCE. (OCTOBER, 1995) - Nevada Lucky Tiger Mill & Mine, Water Tanks, East slope of Buckskin Mountain, Paradise Valley, Humboldt County, NV

  19. 2. WEST REAR, WITH PORTHOLE ESCAPE HATCH ABOVE ENTRY DOOR. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. WEST REAR, WITH PORTHOLE ESCAPE HATCH ABOVE ENTRY DOOR. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  20. Detection of hatching and table egg defects using hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging system was developed to detect problem hatching eggs (non-fertile or dead embryos) prior to or during early incubation and to detect table eggs with blood spots and cracked shells. All eggs were imaged using a hyperspectral camera system (wavelengths detected from 400-900mm) ...

  1. How embryos escape from danger: the mechanism of rapid, plastic hatching in red-eyed treefrogs.

    PubMed

    Cohen, Kristina L; Seid, Marc A; Warkentin, Karen M

    2016-06-15

    Environmentally cued hatching allows embryos to escape dangers and exploit new opportunities. Such adaptive responses require a flexibly regulated hatching mechanism sufficiently fast to meet relevant challenges. Anurans show widespread, diverse cued hatching responses, but their described hatching mechanisms are slow, and regulation of timing is unknown. Arboreal embryos of red-eyed treefrogs, Agalychnis callidryas, escape from snake attacks and other threats by very rapid premature hatching. We used videography, manipulation of hatching embryos and electron microscopy to investigate their hatching mechanism. High-speed video revealed three stages of the hatching process: pre-rupture shaking and gaping, vitelline membrane rupture near the snout, and muscular thrashing to exit through the hole. Hatching took 6.5-49 s. We hypothesized membrane rupture to be enzymatic, with hatching enzyme released from the snout during shaking. To test this, we displaced hatching embryos to move their snout from its location during shaking. The membrane ruptured at the original snout position and embryos became trapped in collapsed capsules; they either moved repeatedly to relocate the hole or shook again and made a second hole to exit. Electron microscopy revealed that hatching glands are densely concentrated on the snout and absent elsewhere. They are full of vesicles in embryos and release most of their contents rapidly at hatching. Agalychnis callidryas' hatching mechanism contrasts with the slow process described in anurans to date and exemplifies one way in which embryos can achieve rapid, flexibly timed hatching to escape from acute threats. Other amphibians with cued hatching may also have novel hatching mechanisms. PMID:27307544

  2. Experimental comparison of rate-dependent hysteresis models in characterizing and compensating hysteresis of piezoelectric tube actuators

    NASA Astrophysics Data System (ADS)

    Aljanaideh, Omar; Habineza, Didace; Rakotondrabe, Micky; Al Janaideh, Mohammad

    2016-04-01

    An experimental study has been carried out to characterize rate-dependent hysteresis of a piezoelectric tube actuator at different excitation frequencies. The experimental measurements were followed by modeling and compensation of the hysteresis nonlinearities of the piezoelectric tube actuator using both the inverse rate-dependent Prandtl-Ishlinskii model (RDPI) and inverse rate-independent Prandtl-Ishlinskii model (RIPI) coupled with a controller. The comparison of hysteresis modeling and compensation of the actuator with both models is presented.

  3. Next-Generation MKIII Lightweight HUT/Hatch Assembly

    NASA Technical Reports Server (NTRS)

    McCarthy, Mike; Toscano, Ralph

    2013-01-01

    The MK III (H-1) carbon-graphite/ epoxy Hard Upper Torso (HUT)/Hatch assembly was designed, fabricated, and tested in the early 1990s. The spacesuit represented an 8.3 psi (˜58 kPa) technology demonstrator model of a zero prebreathe suit. The basic torso shell, brief, and hip areas of the suit were composed of a carbon-graphite/epoxy composite lay-up. In its current configuration, the suit weighs approximately 120 lb (˜54 kg). However, since future planetary suits will be designed to operate at 0.26 bar (˜26 kPa), it was felt that the suit's re-designed weight could be reduced to 79 lb (˜35 kg) with the incorporation of lightweight structural materials. Many robust, lightweight structures based on the technologies of advanced honeycomb materials, revolutionary new composite laminates, metal matrix composites, and recent breakthroughs in fullerene fillers and nanotechnology lend themselves well to applications requiring materials that are both light and strong. The major problem involves the reduction in weight of the HUT/ Hatch assembly for use in lunar and/or planetary applications, while at the same time maintaining a robust structural design. The technical objective is to research, design, and develop manufacturing methods that support fa b rica - tion of a lightweight HUT/Hatch assembly using advanced material and geometric redesign as necessary. Additionally, the lightweight HUT/Hatch assembly will interface directly with current MK III hardware. Using the new operating pressure and current MK III (H-1) interfaces as a starting block, it is planned to maximize HUT/Hatch assembly weight reduction through material selection and geometric redesign. A hard upper torso shell structure with rear-entry closure and corresponding hatch will be fabricated. The lightweight HUT/Hatch assembly will retrofit and interface with existing MK III (H-1) hardware elements, providing NASA with immediate "plug-andplay" capability. NASA crewmembers will have a lightweight

  4. Dependence of the Firearm-Related Homicide Rate on Gun Availability: A Mathematical Analysis

    PubMed Central

    Wodarz, Dominik; Komarova, Natalia L.

    2013-01-01

    In the USA, the relationship between the legal availability of guns and the firearm-related homicide rate has been debated. It has been argued that unrestricted gun availability promotes the occurrence of firearm-induced homicides. It has also been pointed out that gun possession can protect potential victims when attacked. This paper provides a first mathematical analysis of this tradeoff, with the goal to steer the debate towards arguing about assumptions, statistics, and scientific methods. The model is based on a set of clearly defined assumptions, which are supported by available statistical data, and is formulated axiomatically such that results do not depend on arbitrary mathematical expressions. According to this framework, two alternative scenarios can minimize the gun-related homicide rate: a ban of private firearms possession, or a policy allowing the general population to carry guns. Importantly, the model identifies the crucial parameters that determine which policy minimizes the death rate, and thus serves as a guide for the design of future epidemiological studies. The parameters that need to be measured include the fraction of offenders that illegally possess a gun, the degree of protection provided by gun ownership, and the fraction of the population who take up their right to own a gun and carry it when attacked. Limited data available in the literature were used to demonstrate how the model can be parameterized, and this preliminary analysis suggests that a ban of private firearm possession, or possibly a partial reduction in gun availability, might lower the rate of firearm-induced homicides. This, however, should not be seen as a policy recommendation, due to the limited data available to inform and parameterize the model. However, the model clearly defines what needs to be measured, and provides a basis for a scientific discussion about assumptions and data. PMID:23923062

  5. Dependence of the firearm-related homicide rate on gun availability: a mathematical analysis.

    PubMed

    Wodarz, Dominik; Komarova, Natalia L

    2013-01-01

    In the USA, the relationship between the legal availability of guns and the firearm-related homicide rate has been debated. It has been argued that unrestricted gun availability promotes the occurrence of firearm-induced homicides. It has also been pointed out that gun possession can protect potential victims when attacked. This paper provides a first mathematical analysis of this tradeoff, with the goal to steer the debate towards arguing about assumptions, statistics, and scientific methods. The model is based on a set of clearly defined assumptions, which are supported by available statistical data, and is formulated axiomatically such that results do not depend on arbitrary mathematical expressions. According to this framework, two alternative scenarios can minimize the gun-related homicide rate: a ban of private firearms possession, or a policy allowing the general population to carry guns. Importantly, the model identifies the crucial parameters that determine which policy minimizes the death rate, and thus serves as a guide for the design of future epidemiological studies. The parameters that need to be measured include the fraction of offenders that illegally possess a gun, the degree of protection provided by gun ownership, and the fraction of the population who take up their right to own a gun and carry it when attacked. Limited data available in the literature were used to demonstrate how the model can be parameterized, and this preliminary analysis suggests that a ban of private firearm possession, or possibly a partial reduction in gun availability, might lower the rate of firearm-induced homicides. This, however, should not be seen as a policy recommendation, due to the limited data available to inform and parameterize the model. However, the model clearly defines what needs to be measured, and provides a basis for a scientific discussion about assumptions and data. PMID:23923062

  6. Dependence of the phototropic response of Arabidopsis thaliana on fluence rate and wavelength

    PubMed Central

    Konjević, Radomir; Steinitz, Benjamin; Poff, Kenneth L.

    1989-01-01

    In the phototropic response of Arabidopsis thaliana seedlings, the shape of the fluence-response relation depends on fluence rate and wavelength. At low fluence rates, the response to 450-nm light is characterized by a single maximum at about 0.3 μmol·m-2. At higher fluence rates, the response shows two distinct maxima, I and II, at 0.3 and 3.5 μmol·m-2, respectively. The response to 500-nm light shows a single maximum at 2 μmol·m-2, and the response to 510-nm light shows a single maximum at 4.5 μmol·m-2, independent of fluence rate. The response to 490-nm light shows a maximal at 4.5 μmol·m-2 and a shoulder at about 0.6 μmol·m-2. Preirradiation with high-fluence 510-nm light from above, immediately followed by unilateral 450-nm light, eliminates maximum II but not maximum I. Preirradiation with high-fluence 450-nm light from above eliminates the response to subsequent unilateral irradiation with either 450-nm or 510-nm light. The recovery of the response following high-fluence 450-nm light is considerably slower than the recovery following high-fluence 510-nm light. Unilateral irradiation with low-fluence 510-nm light followed by 450-nm light results in curvature that is approximately the sum of those produced by either irradiation alone. Based on these results, it is proposed that phototropism in A. thaliana seedlings is mediated by at least two blue-light photoreceptor pigments. PMID:16594094

  7. Hatch: Moving towards seamless database protocols for ecological data

    NASA Astrophysics Data System (ADS)

    Fremier, A. K.; Blair, C.; Smith, S.; Weigel, D.; Newsom, M. A.

    2013-12-01

    Data collection and ecological processes do not occur at similar scales. Monitoring our environment, therefore, requires research approaches that integrate data across spatial and temporal scales. Despite the enormous amount of data being collected annually, many government agencies are only now beginning to build coordinated data management systems. With efficient data flows and coded analysis tools, researchers will be better prepared to quickly answer key ecological questions across datasets. In this project, we designed an online platform for seamless data management, called Hatch. Our aim is to improve database protocols and data access to allow timely analysis of existing data, across time and space. Hatch is being developed for ecological monitoring of stream ecosystems in the Methow River basin in Washington State; however, the platform is general enough for managing multiple forms of database types. Hatch currently applies both a schema and schema-less database structure to link data collection events. It applies data standards developed and accepted across the Columbia River Basin. Initial data capture is driven by data needs for a mechanism-based model of ecosystem processes (namely periphyton production). Input data files, both past and current flows, are validated and stored along with metadata. Data search tools are being designed in accordance with data sharing agreements with appropriate security. The goal of Hatch is to defragment the analysis workspace by integrating data capture, search and analysis. Hatch helps researchers capture, search and analyze data in an online, flexible platform while conforming to project a specific schema. With less fragmented database protocols, scientists will be better prepared to efficiently answer scientific questions at relevant ecological scales.

  8. Extended incubation affects larval morphology, hatching success and starvation resistance in a terrestrially spawning fish, Galaxias maculatus (Jenyns 1842).

    PubMed

    Semmens, D; Swearer, S E

    2011-10-01

    The effect of extended incubation (delayed hatching) on larval morphology in the terrestrially spawning common galaxias Galaxias maculatus was investigated by inducing larvae to hatch 1 and 2 weeks after the normal 2 week incubation period. After 1 week of extended incubation, larvae were larger (longer in standard length, L(S), and greater in body depth) compared to controls (larvae that experienced normal incubation durations). After 2 weeks of extended incubation, larvae were smaller (shorter in L(S) and smaller in body depth) than larvae that experienced 1 week of extended incubation. Furthermore, eye area increased while yolk-sac size decreased monotonically with increasing incubation duration. These results suggest that larvae experiencing long periods of extended incubation are using somatic tissue to meet their metabolic demands. Larvae that experienced 2 weeks of extended incubation succumbed to starvation sooner than control larvae, but hatching success was not significantly different. Temperature mediated the effect of extended incubation on the morphology of larvae at hatching, most likely, through its effects on developmental rate and efficiency of yolk utilization. This study demonstrates some of the consequences of terrestrial spawning with extended incubation, which will assist in determining why this intriguing behaviour has evolved several times in a diverse range of taxa. PMID:21967585

  9. Factors Affecting Growth of Tengmalm’s Owl (Aegolius funereus) Nestlings: Prey Abundance, Sex and Hatching Order

    PubMed Central

    Zárybnická, Markéta; Riegert, Jan; Brejšková, Lucie; Šindelář, Jiří; Kouba, Marek; Hanel, Jan; Popelková, Alena; Menclová, Petra; Tomášek, Václav; Šťastný, Karel

    2015-01-01

    In altricial birds, energy supply during growth is a major predictor of the physical condition and survival prospects of fledglings. A number of experimental studies have shown that nestling body mass and wing length can vary with particular extrinsic factors, but between-year observational data on this topic are scarce. Based on a seven-year observational study in a central European Tengmalm’s owl population we examine the effect of year, brood size, hatching order, and sex on nestling body mass and wing length, as well as the effect of prey abundance on parameters of growth curve. We found that nestling body mass varied among years, and parameters of growth curve, i.e. growth rate and inflection point in particular, increased with increasing abundance of the owl’s main prey (Apodemus mice, Microtus voles), and pooled prey abundance (Apodemus mice, Microtus voles, and Sorex shrews). Furthermore, nestling body mass varied with hatching order and between sexes being larger for females and for the first-hatched brood mates. Brood size had no effect on nestling body mass. Simultaneously, we found no effect of year, brood size, hatching order, or sex on the wing length of nestlings. Our findings suggest that in this temperate owl population, nestling body mass is more sensitive to prey abundance than is wing length. The latter is probably more limited by the physiology of the species. PMID:26444564

  10. A single-rate context-dependent learning process underlies rapid adaptation to familiar object dynamics.

    PubMed

    Ingram, James N; Howard, Ian S; Flanagan, J Randall; Wolpert, Daniel M

    2011-09-01

    Motor learning has been extensively studied using dynamic (force-field) perturbations. These induce movement errors that result in adaptive changes to the motor commands. Several state-space models have been developed to explain how trial-by-trial errors drive the progressive adaptation observed in such studies. These models have been applied to adaptation involving novel dynamics, which typically occurs over tens to hundreds of trials, and which appears to be mediated by a dual-rate adaptation process. In contrast, when manipulating objects with familiar dynamics, subjects adapt rapidly within a few trials. Here, we apply state-space models to familiar dynamics, asking whether adaptation is mediated by a single-rate or dual-rate process. Previously, we reported a task in which subjects rotate an object with known dynamics. By presenting the object at different visual orientations, adaptation was shown to be context-specific, with limited generalization to novel orientations. Here we show that a multiple-context state-space model, with a generalization function tuned to visual object orientation, can reproduce the time-course of adaptation and de-adaptation as well as the observed context-dependent behavior. In contrast to the dual-rate process associated with novel dynamics, we show that a single-rate process mediates adaptation to familiar object dynamics. The model predicts that during exposure to the object across multiple orientations, there will be a degree of independence for adaptation and de-adaptation within each context, and that the states associated with all contexts will slowly de-adapt during exposure in one particular context. We confirm these predictions in two new experiments. Results of the current study thus highlight similarities and differences in the processes engaged during exposure to novel versus familiar dynamics. In both cases, adaptation is mediated by multiple context-specific representations. In the case of familiar object dynamics

  11. A Model for Rate-Dependent Hysteresis in Piezoceramic Materials Operating at Low Frequencies

    NASA Technical Reports Server (NTRS)

    Smith, Ralph C.; Ounaies, Zoubeida; Wieman, Robert

    2001-01-01

    This paper addresses the modeling of certain rate-dependent mechanisms which contribute to hysteresis inherent to piezoelectric materials operating at low frequencies. While quasistatic models are suitable for initial material characterization in some applications, the reduction in coercive field and polarization values which occur as frequencies increase must be accommodated to achieve the full capabilities of the materials. The model employed here quantifies the hysteresis in two steps. In the first, anhysteretic polarization switching is modeled through the application of Boltzmann principles to balance the electrostatic and thermal energy. Hysteresis is then incorporated through the quantification of energy required to translate and bend domain walls pinned at inclusions inherent to the materials. The performance of the model is illustrated through a fit to low frequency data (0.1 Hz - 1 Hz) from a PZT5A wafer.

  12. Pressure dependence on the reaction propagation rate of PETN at high pressure

    SciTech Connect

    Foltz, M.F.

    1993-04-01

    The reaction propagation rate (RPR) of the sensitive high explosive pentaerythritol tetranitrate (PETN) was measured in a diamond anvil cell (DAC) over the pressure range of 2--20 GPa. The experimental technique used is the same as that previously reported. The RPR data shows that it burns one to two orders of magnitude faster in the DAC than 1,3,5,-triamino-2,4,6-trinitrobenzene (TATB) and nitromethane (CH{sub 3}NO{sub 2}) respectively. The PETN RPR curve did not show sample pressure-dependent behavior like that of nitromethane, but instead varied abruptly like the RPR curve of TATB. In order to interpret these changes, static-pressure DAC mid-IR FTIR spectra were taken of micro-pellets of PETN embedded in KBr. The relationship between changes in the spectra, the RPR curve, and published single crystal PETN wedge test data are discussed.

  13. The dependence of irradiation creep in austenitic alloys on displacement rate and helium to dpa ratio

    SciTech Connect

    Garner, F.A.; Toloczko, M.B.; Grossbeck, M.L.

    1998-03-01

    Before the parametric dependencies of irradiation creep can be confidently determined, analysis of creep data requires that the various creep and non-creep strains be separated, as well as separating the transient, steady-state, and swelling-driven components of creep. When such separation is attained, it appears that the steady-state creep compliance, B{sub o}, is not a function of displacement rate, as has been previously assumed. It also appears that the formation and growth of helium bubbles under high helium generation conditions can lead to a significant enhancement of the irradiation creep coefficient. This is a transient influence that disappears as void swelling begins to dominate the total strain, but this transient can increase the apparent creep compliance by 100--200% at relatively low ({le}20) dpa levels.

  14. Temperature dependence of the NO + O3 reaction rate from 195 to 369 K

    NASA Technical Reports Server (NTRS)

    Michael, J. V.; Allen, J. E., Jr.; Brobst, W. D.

    1981-01-01

    The temperature dependence of the NO + O3 reaction rate was examined by means of the fast flow technique. Several different experimental conditions and detection schemes were employed. With excess NO or excess O3, NO2 chemiluminescence was monitored. In addition, with excess O3, NO was followed by fluorescence induced by an NO microwave discharge lamp. The results of the three independent sets of data are compared and found to agree within experimental error, indicating the absence of secondary chemistry which might complicate the kinetics. The data exhibit curvature on an Arrhenius plot; however, the simple Arrhenius expression k = (2.6 + or - 0.8) x 10 to the -12th exp(-1435 + or - 64/T) cu cm/molecule s is an adequate description for T between 195 and 369 K. This result is compared to earlier determinations.

  15. Size dependence of surface thermodynamic properties of nanoparticles and its determination method by reaction rate constant

    NASA Astrophysics Data System (ADS)

    Li, Wenjiao; Xue, Yongqiang; Cui, Zixiang

    2016-08-01

    Surface thermodynamic properties are the fundamental properties of nanomaterials, and these properties depend on the size of nanoparticles. In this paper, relations of molar surface thermodynamic properties and surface heat capacity at constant pressure of nanoparticles with particle size were derived theoretically, and the method of obtaining the surface thermodynamic properties by reaction rate constant was put forward. The reaction of nano-MgO with sodium bisulfate solution was taken as a research system. The influence regularities of the particle size on the surface thermodynamic properties were discussed theoretically and experimentally, which show that the experimental regularities are in accordance with the corresponding theoretical relations. With the decreasing of nanoparticle size, the molar surface thermodynamic properties increase, while the surface heat capacity decreases (the absolute value increases). In addition, the surface thermodynamic properties are linearly related to the reciprocal of nanoparticle diameter, respectively.

  16. Substrate orientation dependence on the solid phase epitaxial growth rate of Ge

    NASA Astrophysics Data System (ADS)

    Darby, B. L.; Yates, B. R.; Martin-Bragado, I.; Gomez-Selles, J. L.; Elliman, R. G.; Jones, K. S.

    2013-01-01

    The solid phase epitaxial growth process has been studied at 330 °C by transmission electron microscopy for Ge wafers polished at 10°-15° increments from the [001] to [011] orientations. The velocity showed a strong dependence on substrate orientation with the [001] direction displaying a velocity 16 times greater than the [111] direction. A lattice kinetic Monte Carlo model was used to simulate solid phase epitaxial growth (SPEG) rates at different orientations, and simulations compared well with experimental results. Cross sectional transmission electron microscopy and plan view transmission electron microscopy revealed stacking fault and twin defect formation in the [111] orientation where all other orientations showed only hairpin dislocations. The twin defects formed from Ge SPEG were comparatively less dense than what has previously been reported for Si, which gave rise to higher normalized velocities and a constant [111] SPEG velocity for Ge.

  17. Irradiation swelling behavior and its dependence on temperature, dose rate and dislocation structure evolution

    SciTech Connect

    Surh, M P; Sturgeon, J B; Wolfer, W G

    2004-01-16

    The microstructural evolution of high purity steel under irradiation is modeled including a dislocation density that evolves simultaneously with void nucleation and growth. The predicted void swelling trends versus temperature, flux, and time are compared to experiment and to earlier calculations with a fixed dislocation density. The behavior is further analyzed within a simplified picture of segregation of irradiation defects to microstructural sinks. Agreement with experimental swelling behavior improves when dislocations co-evolve with the void content versus simulations with a fixed dislocation density. The time-dependent dislocation content dictates the rate of void nucleation and shapes the overall void size distribution so as to give steady swelling behavior over long times.

  18. Global stability of a delayed SIR epidemic model with density dependent birth and death rates

    NASA Astrophysics Data System (ADS)

    Yoshida, Naoki; Hara, Tadayuki

    2007-04-01

    An SIR epidemic model with density dependent birth and death rates is formulated. In our model it is assumed that the total number of the population is governed by logistic equation. The transmission of infection is assumed to be of the standard form, namely proportional to I(t-h)/N(t-h) where N(t) is the total (variable) population size, I(t) is the size of the infective population and a time delay h is a fixed time during which the infectious agents develop in the vector. We consider transmission dynamics for the model. Stability of an endemic equilibrium is investigated. The stability result is stated in terms of a threshold parameter, that is, a basic reproduction number R0.

  19. Oncogenic transformation through the cell cycle and the LET dependent inverse dose rate effect

    NASA Technical Reports Server (NTRS)

    Geard, C. R.; Miller, R. C.; Brenner, D. J.; Hall, E. J.; Wachholz, B. W. (Principal Investigator)

    1994-01-01

    Synchronised populations of mouse C3H/10T-1/2 cells were obtained by a stringent mitotic dislodgment procedure. Mitotic cells rapidly attach and progress sequentially through the cell cycle. Irradiation (3 Gy of X rays) was carried out at intervals from 0 to 18 h after initiating cell cycle progression of the mitotic cells. Oncogenic transformation was enhanced 10-fold over cells irradiated soon after replating (G1 and S phases) for cells in a near 2 h period corresponding to cells in G2 phase but not in mitosis. The cell surviving fraction had a 2-1/2-fold variation with resistant peaks corresponding to the late G1 and late S phases. These findings provide experimental support for the hypothesis initiated by Rossi and Kellerer and developed by Brenner and Hall to explain the LET dependent inverse dose rate effect for oncogenic transformation.

  20. Growth rates of rhizosphere microorganisms depend on competitive abilities of plants for nitrogen

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Littschwager, Johanna; Lauerer, Marianna; Kuzyakov, Yakov

    2010-05-01

    Rhizosphere - one of the most important ‘hot spots' in soil - is characterized not only by accelerated turnover of microbial biomass and nutrients but also by strong intra- and inter-specific competition. Intra-specific competition occurs between individual plants of the same species, while inter-specific competition can occur both at population level (plant species-specific, microbial species-specific interactions) and at community level (plant - microbial interactions). Such plant - microbial interactions are mainly governed by competition for available N sources, since N is one of the main growth limiting nutrients in natural ecosystems. Functional structure and activity of microbial community in rhizosphere is not uniform and is dependent on quantity and quality of root exudates which are plant specific. It is still unclear how microbial growth and turnover in the rhizosphere are dependent on the features and competitive abilities of plants for N. Depending on C and N availability, acceleration and even retardation of microbial activity and carbon mineralization can be expected in the rhizosphere of plants with high competitive abilities for N. We hypothesized slower microbial growth rates in the rhizosphere of plants with smaller roots, as they usually produce less exudates compared to plants with small shoot-to-root ratio. As the first hypothesis is based solely on C availability, we also expected the greater effect of N availability on microbial growth in rhizosphere of plants with smaller root mass. These hypothesis were tested for two plant species of strawberry: Fragaria vesca L. (native species), and Duchesnea indica (Andrews) Focke (an invasive plant in central Europe) growing in intraspecific and interspecific competition. Microbial biomass and the kinetic parameters of microbial growth in the rhizosphere were estimated by dynamics of CO2 emission from the soil amended with glucose and nutrients. Specific growth rate (µ) of soil microorganisms was

  1. Does the CO-to-H2 conversion factor depend on the star formation rate?

    NASA Astrophysics Data System (ADS)

    Clark, Paul C.; Glover, Simon C. O.

    2015-09-01

    We present a series of numerical simulations that explore how the `X-factor', XCO - the conversion factor between the observed integrated CO emission and the column density of molecular hydrogen - varies with the environmental conditions in which a molecular cloud is placed. Our investigation is centred around two environmental conditions in particular: the cosmic ray ionization rate (CRIR) and the strength of the interstellar radiation field (ISRF). Since both these properties of the interstellar medium (ISM) have their origins in massive stars, we make the assumption in this paper that both the strength of the ISRF and the CRIR scale linearly with the local star formation rate (SFR). The cloud modelling in this study first involves running numerical simulations that capture the cloud dynamics, as well as the time-dependent chemistry, and ISM heating and cooling. These simulations are then post-processed with a line radiative transfer code to create synthetic 12CO (1-0) emission maps from which XCO can be calculated. We find that for 104 M⊙ virialized clouds with mean density 100 cm- 3, XCO is only weakly dependent on the local SFR, varying by a factor of a few over 2 orders of magnitude in SFR. In contrast, we find that for similar clouds but with masses of 105 M⊙, the X-factor will vary by an order of magnitude over the same range in SFR, implying that extragalactic star formation laws should be viewed with caution. However, for denser (104 cm- 3), supervirial clouds such as those found at the centre of the Milky Way, the X-factor is once again independent of the local SFR.

  2. Earthquake nucleation on faults with rate-and state-dependent strength

    USGS Publications Warehouse

    Dieterich, J.H.

    1992-01-01

    Dieterich, J.H., 1992. Earthquake nucleation on faults with rate- and state-dependent strength. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 115-134. Faults with rate- and state-dependent constitutive properties reproduce a range of observed fault slip phenomena including spontaneous nucleation of slip instabilities at stresses above some critical stress level and recovery of strength following slip instability. Calculations with a plane-strain fault model with spatially varying properties demonstrate that accelerating slip precedes instability and becomes localized to a fault patch. The dimensions of the fault patch follow scaling relations for the minimum critical length for unstable fault slip. The critical length is a function of normal stress, loading conditions and constitutive parameters which include Dc, the characteristic slip distance. If slip starts on a patch that exceeds the critical size, the length of the rapidly accelerating zone tends to shrink to the characteristic size as the time of instability approaches. Solutions have been obtained for a uniform, fixed-patch model that are in good agreement with results from the plane-strain model. Over a wide range of conditions, above the steady-state stress, the logarithm of the time to instability linearly decreases as the initial stress increases. Because nucleation patch length and premonitory displacement are proportional to Dc, the moment of premonitory slip scales by D3c. The scaling of Dc is currently an open question. Unless Dc for earthquake faults is significantly greater than that observed on laboratory faults, premonitory strain arising from the nucleation process for earthquakes may by too small to detect using current observation methods. Excluding the possibility that Dc in the nucleation zone controls the magnitude of the subsequent earthquake, then the source dimensions of the smallest

  3. Stability of the rate, state and temperature dependent friction model and its applications

    NASA Astrophysics Data System (ADS)

    Singh, Arun K.; Singh, Trilok N.

    2016-04-01

    In this paper, we study stability of the rate, state and temperature friction (RSTF) model. The Segall and Rice approach is used to model heat transfer at the sliding interface with its surroundings. The effect of pore pressure is not considered in the model to avoid the complex expression for critical stiffness. Linear stability analysis of the spring-mass sliding system is carried out with the ageing law under the quasistatic conditions in order to determine the critical stiffness above which sliding behaviour changes from unstable to stable or vice versa. Our numerical simulations establish that critical stiffness of the heated surface may increase or decrease from corresponding to the critical stiffness of the unheated surface depending on the relative values of two contradictory parameters related with velocity effect and temperature effect. Parametric studies are also carried out to understand shear velocity and temperature of the sliding surface dependence of steady friction. The RSTF model is also used to study the gravity induced failure of a creeping rock slope and the results are justified.

  4. Model for charge/discharge-rate-dependent plastic flow in amorphous battery materials

    NASA Astrophysics Data System (ADS)

    Khosrownejad, S. M.; Curtin, W. A.

    2016-09-01

    Plastic flow is an important mechanism for relaxing stresses that develop due to swelling/shrinkage during charging/discharging of battery materials. Amorphous high-storage-capacity Li-Si has lower flow stresses than crystalline materials but there is evidence that the plastic flow stress depends on the conditions of charging and discharging, indicating important non-equilibrium aspects to the flow behavior. Here, a mechanistically-based constitutive model for rate-dependent plastic flow in amorphous materials, such as LixSi alloys, during charging and discharging is developed based on two physical concepts: (i) excess energy is stored in the material during electrochemical charging and discharging due to the inability of the amorphous material to fully relax during the charging/discharging process and (ii) this excess energy reduces the barriers for plastic flow processes and thus reduces the applied stresses necessary to cause plastic flow. The plastic flow stress is thus a competition between the time scales of charging/discharging and the time scales of glassy relaxation. The two concepts, as well as other aspects of the model, are validated using molecular simulations on a model Li-Si system. The model is applied to examine the plastic flow behavior of typical specimen geometries due to combined charging/discharging and stress history, and the results generally rationalize experimental observations.

  5. Cold Season Mortality Under Natural Conditions and Subsequent Hatching Response of Aedes (Stegomyia) aegypti (Diptera: Culicidae) Eggs in a Subtropical City of Argentina.

    PubMed

    Giménez, Javier Orlando; Fischer, Sylvia; Zalazar, Laura; Stein, Marina

    2015-09-01

    In temperate and subtropical regions, populations of Aedes (Stegomyia) aegypti (L.) survive unfavorable winter conditions in the egg stage. Knowing their survival rates can be of great interest for the health authorities in charge of control activities. In this study, we analyzed the mortality of Ae. aegypti eggs exposed to the cold season as well as their hatching patterns under laboratory conditions in the city of Resistencia, Chaco, Argentina. The mortality rate was 48.6%. No statistically significant differences were observed in the mortality of eggs exposed at different sites. Hatching response differed significantly among the successive postexposure immersions, with the highest proportion of hatched eggs during the first immersion. These results show that the mortality rate of Ae. aegypti eggs exposed to the cold season in a subtropical city of Argentina was higher than those from temperate climate region. The additional mortality of eggs in our study might be related to fungal development (an unexpected event), which was not observed in research in temperate climate. The hatching pattern observed in this study ensures a rapid increase of the population at the beginning of the favorable breeding season, but it also maintains a batch with delayed hatching eggs, posing a risk for the community. PMID:26336247

  6. On the temperature dependence of the rate coefficient of formation of C2+ from C + CH+

    NASA Astrophysics Data System (ADS)

    Rampino, S.; Pastore, M.; Garcia, E.; Pacifici, L.; Laganà, A.

    2016-08-01

    We carry out quasi-classical trajectory calculations for the C + CH+→ C_2^+ + H reaction on an ad hoc computed high-level ab initio potential energy surface. Thermal rate coefficients at the temperatures of relevance in cold interstellar clouds are derived and compared with the assumed, temperature-independent estimates publicly available in kinetic data bases KIDA and UDfA. For a temperature of 10 K the data base value overestimates by a factor of 2 the one obtained by us (thus improperly enhancing the destruction route of CH+ in astrochemical kinetic models) which is seen to double in the temperature range 5-300 K with a sharp increase in the first 50 K. The computed values are fitted via the popular Arrhenius-Kooij formula and best-fitting parameters α = 1.32 × 10-9 cm3 s-1, β = 0.1 and γ = 2.19 K to be included in the online mentioned data bases are provided. Further investigation shows that the temperature dependence of the thermal rate coefficient better conforms to the recently proposed so-called `deformed Arrhenius' law by Aquilanti and Mundim.

  7. Rate Dependency During Relaxation of Superelastic Orthodontic NiTi Alloys After Hydrogen Charging

    NASA Astrophysics Data System (ADS)

    Elkhal Letaief, Wissem; Hassine, Tarek; Gamaoun, Fehmi

    2016-03-01

    The relaxation behavior under tensile loading of a superelastic NiTi alloy was investigated after hydrogen charging with respect to aging from one to 77 days in air at room temperature. The specimens were immersed for 3 h in a 0.9 % NaCl aqueous solution and then relaxed with an imposed strain of 4.8 %—which results in half of the martensite transformation—for different strain rates of 10-4, 10-3, and 5 × 10-3 s-1. For the non-charged specimens, the relaxed stress at the beginning exhibited a temporary dependence on the strain rates and then reached the same equilibrium stress after 2.5 h. After hydrogen charging, this equilibrium stress did not vary for the as-charged specimen. Nevertheless, the greater the aging period is the greater the equilibrium stress is. This behavior can be attributed to the diffusion of hydrogen into the entire specimen, which hinders the relaxation mechanism of the martensite bands.

  8. Long range dependence in the high frequency USD/INR exchange rate

    NASA Astrophysics Data System (ADS)

    Kumar, Dilip

    2014-02-01

    Using high frequency data, this paper examines the long memory property in the unconditional and conditional volatility of the USD/INR exchange rate at different time scales using the Local Whittle (LW), the Exact Local Whittle (ELW) and the FIAPARCH models. Results indicate that the long memory property remains quite stable across different time scales for both unconditional and conditional volatility measures. Results from the non-overlapping moving window approach indicate that the extreme events (such as the subprime crisis and the European debt crisis) resulted in highly persistent behavior of the USD/INR exchange rate and thus lead to market inefficiency. This paper also examines the long memory property in the realized volatility based on different time scale data. Results indicate that the realized volatility measures based on different scales of the high frequency data exhibit a consistent and stable long memory property. However, the realized volatility measures based on daily data exhibit lower degree of long-range dependence. This study has implications for traders and investors (with different trading horizons) and can be helpful in predicting expected future volatility and in designing and implementing trading strategies at different time scales.

  9. STS-38 Pilot Culbertson rolls through CCT side hatch during egress training

    NASA Technical Reports Server (NTRS)

    1990-01-01

    STS-38 Pilot Frank L. Culbertson, wearing launch and entry suit (LES) and launch and entry helmet (LEH), rolls through the side hatch of the crew compartment trainer (CCT) located in JSC's Mockup and Integration Laboratory (MAIL) Bldg 9A. Assisted by technicians, Culbertson practices emergency egress through the side hatch using the crew escape system (CES) pole which extends out the side hatch. The inflated safety cushion breaks Culbertson's fall as he rolls out of the side hatch.

  10. Comparing Time-Dependent Geomagnetic and Atmospheric Effects on Cosmogenic Nuclide Production Rate Scaling

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.

    2014-12-01

    A recently published cosmogenic nuclide production rate scaling model based on analytical fits to Monte Carlo simulations of atmospheric cosmic ray flux spectra (both of which agree well with measured spectra) (Lifton et al., 2014, Earth Planet. Sci. Lett. 386, 149-160: termed the LSD model) provides two main advantages over previous scaling models: identification and quantification of potential sources of bias in the earlier models, and the ability to generate nuclide-specific scaling factors easily for a wide range of input parameters. The new model also provides a flexible framework for exploring the implications of advances in model inputs. In this work, the scaling implications of two recent time-dependent spherical harmonic geomagnetic models spanning the Holocene will be explored. Korte and Constable (2011, Phys. Earth Planet. Int. 188, 247-259) and Korte et al. (2011, Earth Planet. Sci. Lett. 312, 497-505) recently updated earlier spherical harmonic paleomagnetic models used by Lifton et al. (2014) with paleomagnetic measurements from sediment cores in addition to archeomagnetic and volcanic data. These updated models offer improved accuracy over the previous versions, in part to due to increased temporal and spatial data coverage. With the new models as input, trajectory-traced estimates of effective vertical cutoff rigidity (RC- the standard method for ordering cosmic ray data) yield significantly different time-integrated scaling predictions when compared to the earlier models. These results will be compared to scaling predictions using another recent time-dependent spherical harmonic model of the Holocene geomagnetic field by Pavón-Carrasco et al. (2014, Earth Planet. Sci. Lett. 388, 98-109), based solely on archeomagnetic and volcanic paleomagnetic data, but extending to 14 ka. In addition, the potential effects of time-dependent atmospheric models on LSD scaling predictions will be presented. Given the typical dominance of altitudinal over

  11. Chlorpyrifos is estrogenic and alters embryonic hatching, cell proliferation and apoptosis in zebrafish.

    PubMed

    Yu, Kaimin; Li, Guochao; Feng, Weimin; Liu, Lili; Zhang, Jiayu; Wu, Wei; Xu, Lei; Yan, Yanchun

    2015-09-01

    The potential interference of endocrine disrupting chemicals (EDCs) on aquatic animals and humans has drawn wide attention in recent years. Reports have shown that some organophosphorus pesticides were a kind of EDCs, but their effects on fish species are still under research. In present study, flow cytometry data of HEC-1B cell line showed that chlorpyrifos (CPF) could increase cell proliferation index like 17β-estradiol (E2), but the effect of CPF was weaker than of E2 in the same concentration. Moreover, CPF altered the expression pattern of estrogen-responsive gene VTG and ERα in zebrafish embryos. When exposed to CPF at various concentrations (0, 0.10, 0.25, 0.50, 0.75 and 1.00mg/L) for 48h during the embryo stage, compared with controls, the hatching rate of treated groups significantly increased at the same time and the hatching rate of embryos was proportional to CPF concentration. The mRNA expression levels of c-myc, cyclin D1, Bax and Bcl-2, which are closely related to cell proliferation and cell apoptosis, were disturbed by CPF in zebrafish embryos after exposure treated for 48h. In addition, acridine orange (AO) staining of zebrafish embryos showed that cell apoptosis was appeared in the 0.75, 1.00mg/L CPF treated groups. Taken together, the results obtained in the present study indicated that chlorpyrifos is estrogenic and alters embryonic hatching, cell proliferation and apoptosis in zebrafish. PMID:26079056

  12. Stress-associated cardiovascular reaction masks heart rate dependence on physical load in mice.

    PubMed

    Andreev-Andrievskiy, A A; Popova, A S; Borovik, A S; Dolgov, O N; Tsvirkun, D V; Custaud, M; Vinogradova, O L

    2014-06-10

    When tested on the treadmill mice do not display a graded increase of heart rate (HR), but rather a sharp shift of cardiovascular indices to high levels at the onset of locomotion. We hypothesized that under test conditions cardiovascular reaction to physical load in mice is masked with stress-associated HR increase. To test this hypothesis we monitored mean arterial pressure (MAP) and heart rate in C57BL/6 mice after exposure to stressful stimuli, during spontaneous locomotion in the open-field test, treadmill running or running in a wheel installed in the home cage. Mice were treated with β1-adrenoblocker atenolol (2mg/kg ip, A), cholinolytic ipratropium bromide (2mg/kg ip, I), combination of blockers (A+I), anxiolytic diazepam (5mg/kg ip, D) or saline (control trials, SAL). MAP and HR in mice increased sharply after handling, despite 3weeks of habituation to the procedure. Under stressful conditions of open field test cardiovascular parameters in mice were elevated and did not depend on movement speed. HR values did not differ in I and SAL groups and were reduced with A or A+I. HR was lower at rest in D pretreated mice. In the treadmill test HR increase over speeds of 6, 12 and 18m/min was roughly 1/7-1/10 of HR increase observed after placing the mice on the treadmill. HR could not be increased with cholinolytic (I), but was reduced after sympatholytic (A) or A+I treatment. Anxiolytic (D) reduced heart rate at lower speeds of movement and its overall effect was to unmask the dependency of HR on running speed. During voluntary running in non-stressful conditions of the home cage HR in mice linearly increased with increasing running speeds. We conclude that in test situations cardiovascular reactions in mice are governed predominantly by stress-associated sympathetic activation, rendering efforts to evaluate HR and MAP reactions to workload unreliable. PMID:24802359

  13. Egg characteristics and hatch performance of Athens Canadian Random Bred 1955 meat-type chickens and 2013 Cobb 500 broilers.

    PubMed

    Collins, K E; McLendon, B L; Wilson, J L

    2014-09-01

    Athens Canadian Random Bred (ACRB) chickens, a 1955 meat-type control strain, were incubated with the 2013 Cobb 500 broiler to determine differences in egg composition, conductance values, incubation duration, hatch performance, and yolk utilization. Unincubated ACRB eggs had greater percentage solids than Cobb 500 eggs. The ACRB eggs had a greater solid portion as yolk, whereas the Cobb 500 devoted more solid percentage to albumen. Percentage shell was not different between the strains, but ACRB eggs had 2.7% greater percentage moisture loss after 18 d of incubation than Cobb 500 eggs. Conductance, conductance constant, and conductance standardized to a 100 g egg weight basis were all higher for ACRB eggs than Cobb 500 eggs at 12 and 18 d of incubation. The Cobb 500 chicks hatched 6 h earlier than ACRB chicks. The Cobb 500 incubation duration was 498 h, and the ACRB incubation duration was 504 h. There was no difference between the strains for percentage infertile eggs, embryonic mortality, hatchability, or salable chicks. The ACRB chicks hatched with a smaller dried residual yolk sac as a percentage of chick weight compared with the Cobb 500. Both strains had an average relative yolk-free chick weight of 61% of average initial egg weight. Thus the Cobb 500 eggs had decreased gas exchange across the eggshell, which may have contributed to the earlier hatch and decreased yolk utilization. Modern Cobb 500 broiler embryonic metabolism appears to have either become more dependent on albumen rather than yolk or has become more efficient with yolk reserves during development. Broiler hatch performance does not appear to have changed over the past 58 yr. PMID:25002554

  14. 9 CFR 82.9 - Interstate movement of hatching eggs from a quarantined area.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Interstate movement of hatching eggs... hatching eggs from a quarantined area. Hatching eggs from birds or poultry not known to be infected with or... eggs are accompanied by a permit obtained in accordance with § 82.11; (b) Copies of the...

  15. Efficacy of polymers in combination with biocides as sanitizer of salmonella inoculated broiler hatching eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella contamination of broiler hatching eggs can be carried through the hatchery and with the hatched chick into the broiler house. Commercially available chemical hatching egg sanitizers have achieved acceptable levels of eggshell decontamination of >70% reductions when applied prior to setti...

  16. 123. Pre1911. View forward from near mizzen hatch, starboard side ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    123. Pre-1911. View forward from near mizzen hatch, starboard side showing crew standing on a load of lumber. Note main fife rail, small hatch with cover (possibly original 'lime juice hatch') just aft. Fred Heick Collection. - Ship BALCLUTHA, 2905 Hyde Street Pier, San Francisco, San Francisco County, CA

  17. Ensemble Monte Carlo calculation of the hole initiated impact ionization rate in bulk GaAs and silicon using a k-dependent, numerical transition rate formulation

    NASA Technical Reports Server (NTRS)

    Oguzman, Ismail H.; Wang, Yang; Kolnik, Jan; Brennan, Kevin F.

    1995-01-01

    The hole initiated impact ionization rate in bulk silicon and GaAs is calculated using a numerical formulation of the impact ionization transition rate incorporated into an ensemble Monte Carlo simulation. The transition rate is calculated from Fermi's golden rule using a two-body screened Coulomb interaction including a wavevector dependent dielectric function. It is found that the effective threshold for hole initiated ionization is relatively soft in both materials, that the split-off band dominates the ionization process in GaAs. and that no clear dominance by any one band is observed in silicon, though the rate out of the light hole band is greatest.

  18. Biomolecular Origin of The Rate-Dependent Deformation of Prismatic Enamel

    SciTech Connect

    Zhou, J; Hsiung, L

    2006-07-05

    Penetration deformation of columnar prismatic enamel was investigated using instrumented nanoindentation testing, carried out at three constant strain rates (0.05 s{sup -1}, 0.005 s{sup -1}, and 0.0005 s{sup -1}). Enamel demonstrated better resistance to penetration deformation and greater elastic modulus values were measured at higher strain rates. The origin of the rate-dependent deformation was rationalized to be the shear deformation of nanoscale protein matrix surrounding each hydroxyapatite crystal rods. And the shear modulus of protein matrix was shown to depend on strain rate in a format: G{sub p} = 0.213 + 0.021 ln {dot {var_epsilon}}. Most biological composites compromise reinforcement mineral components and an organic matrix. They are generally partitioned into multi-level to form hierarchical structures that have supreme resistance to crack growth [1]. The molecular mechanistic origin of toughness is associated with the 'sacrificial chains' between the individual sub-domains in a protein molecule [2]. As the protein molecule is stretched, these 'sacrificial chains' break to protect its backbone and dissipate energy [3]. Such fresh insights are providing new momentum toward updating our understanding of biological materials [4]. Prismatic enamel in teeth is one such material. Prismatic microstructure is frequently observed in the surface layers of many biological materials, as exemplified in mollusk shells [5] and teeth [6]. It is a naturally optimized microstructure to bear impact loading and penetration deformation. In teeth, the columnar prismatic enamel provides mechanical and chemical protection for the relatively soft dentin layer. Its mechanical behavior and reliability are extremely important to ensure normal tooth function and human health. Since enamel generally contains up to 95% hydroxyapatite (HAP) crystals and less than 5% protein matrix, it is commonly believed to be a weak and brittle material with little resistance to fracture [7]. This

  19. Hatching Time and Alevin Growth Prior to the Onset of Exogenous Feeding in Farmed, Wild and Hybrid Norwegian Atlantic Salmon

    PubMed Central

    Solberg, Monica Favnebøe; Fjelldal, Per Gunnar; Nilsen, Frank; Glover, Kevin Alan

    2014-01-01

    The onset of exogenous feeding, when juveniles emerge from the gravel, is a critical event for salmonids where early emergence and large size provide a competitive advantage in the wild. Studying 131 farmed, hybrid and wild Norwegian Atlantic salmon families, originating from four wild populations and two commercial strains, we investigated whether approximately 10 generations of selection for faster growth has also resulted in increased somatic growth prior to the onset of exogenous feeding. In addition, we tested whether relaxed selection in farms has allowed for alterations in hatching time between farmed and wild salmon. Across three cohorts, wild salmon families hatched earlier than farmed salmon families, while hybrid families displayed intermediate hatching times. While the observed differences were small, i.e., 1–15 degree-days (0–3 days, as water temperatures were c. 5–6°C), these data suggest additive genetic variation for hatching time. Alevin length prior to exogenous feeding was positively related to egg size. After removal of egg size effects, no systematic differences in alevin length were observed between the wild and farmed salmon families. While these results indicate additive genetic variation for egg development timing, and wild salmon families consistently hatched earlier than farmed salmon families, these differences were so small they are unlikely to significantly influence early life history competition of farmed and wild salmon in the natural environment. This is especially the case given that the timing of spawning among females can vary by several weeks in some rivers. The general lack of difference in size between farmed and wild alevins, strongly suggest that the documented differences in somatic growth rate between wild and farmed Norwegian Atlantic salmon under hatchery conditions are first detectable after the onset of exogenous feeding. PMID:25438050

  20. A Regional Scale Earthquake Simulator for Faults With Rate- and State-Dependent Frictional Properties

    NASA Astrophysics Data System (ADS)

    Richards-Dinger, K.; Dieterich, J.

    2006-12-01

    Long-term (~10,000 year) catalogs of simulated earthquakes can be used to address a host of questions related to both seismic hazard calculations and more fundamental issues of earthquake occurrence and interaction (e.g. Ward [1996], Rundle et al. [2004], Ziv and Rubin [2000, 2003]). The quasi-static models of Ziv and Rubin [2000, 2003] are based on the computational strategy of Dieterich [1995] for efficiently computing large numbers of earthquakes, including the seismic nucleation process on faults with rate- and state-dependent frictional properties. Both Dieterich [1995] and Ziv and Rubin [2000, 2003] considered only single planar faults embedded in a whole-space. Faults in nature are not geometrically flat nor do they exist in isolation but form complex networks. Slip of such networks involves processes and interactions that do not occur in planar fault models and may strongly affect earthquake processes. We are in the process of constructing simulations of earthquake occurrence in complex, regional-scale fault networks whose elements obey rate- and state-dependent frictional laws. The solutions of Okada [1992] for dislocations in an elastic half-space are used to calculate the stress interaction coefficients between the elements. We employ analytic solutions for the nucleation process that include the effects of time-varying normal stress. At the time of this abstract we have conducted initial experiments with a single 100 km x 15 km strike-slip fault which produce power-law magnitude distributions with reasonable b-values. The model is computationally efficient - simulations of 50,000 events on a fault with 1500 elements require about seven minutes on a single 2.5 GHz CPU. The very largest events (which rupture nearly the entire fault) occur quasi-periodically, whereas the entire catalog displays temporal clustering in that its waiting time distribution is a power-law with a slope similar to that observed for actual seismicity in both California and Iceland

  1. Fundamental Study on Temperature Dependence of Deposition Rate of Silicic Acid - 13270

    SciTech Connect

    Shinmura, Hayata; Niibori, Yuichi; Mimura, Hitoshi

    2013-07-01

    The dynamic behavior of the silicic acid is one of the key factors to estimate the condition of the repository system after the backfill. This study experimentally examined the temperature dependence of dynamic behavior of supersaturated silicic acid in the co-presence of solid phase, considering Na ions around the repository, and evaluated the deposition rate constant, k, of silicic acid by using the first-order reaction equation considering the specific surface area. The values of k were in the range of 1.0x10{sup -11} to 1.0x10{sup -9} m/s in the temperature range of 288 K to 323 K. The deposition rate became larger with increments of temperature under the Na ion free condition. Besides, in the case of Na ions 0.6 M, colloidal silicic acid decreased dramatically at a certain time. This means that the diameter of the colloidal silicic acid became larger than the pore size of filter (0.45 μm) due to bridging of colloidal silicic acid. Furthermore, this study estimated the range of altering area and the aperture of flow-path in various value of k corresponding to temperature by using advection-dispersion model. The concentration in the flow-path became lower with increments of temperature, and when the value of k is larger than 1.0x10{sup -11} m/s, the deposition range of supersaturated silicic acid was estimated to be less than 20 m around the repository. In addition, the deposition of supersaturated silicic acid led the decrement of flow-path aperture, which was remarkable under the condition of relatively high temperature. Such a clogging in flow paths is expected as a retardation effect of radionuclides. (authors)

  2. Linker dependence of interfacial electron transfer rates in Fe(II)-polypyridine sensitized solar cells.

    PubMed

    Bowman, David N; Mukherjee, Sriparna; Barnes, Lyndsay J; Jakubikova, Elena

    2015-04-10

    Dye-sensitized solar cells (DSSCs) convert solar energy to electricity employing dye molecules attached to a semiconductor surface. Some of the most efficient DSSCs use Ru-based chromophores. Fe-based dyes represent a cheaper and more environmentally friendly alternative to these expensive and toxic dyes. The photoactive state of Fe-based chromophores responsible for charge-separation at the dye-semiconductor interface is, however, deactivated on a sub-picosecond time scale via the intersystem crossing (ISC) into a manifold of low-lying photo-inactive quintet states. Therefore, development of Fe-based dyes capable of fast interfacial electron transfer (IET) leading to efficient charge separation on a time scale competitive with the ISC events is important. This work investigates how linker groups anchoring a prototypical Fe-based dye [Fe(bpy-L)2(CN)2] (bpy = 2,2'-bipyridine, L = linker group) onto the TiO2 semiconductor surface influence the IET rates in the dye-semiconductor assemblies. Linker groups investigated include carboxylic acid, phosphonic acid, hydroxamate, catechol, and acetylacetonate. We employ time-dependent density functional theory (TD-DFT) to obtain absorption spectra of [Fe(bpy-L)2(CN)2] with each linker, and quantum dynamics simulations to investigate the IET rates between the dye and the (101) TiO2 anatase surface. For all attachments, TD-DFT calculations show similar absorption spectra with two main bands corresponding to the metal-to-ligand charge transfer transitions. The quantum dynamics simulations predict that the utilization of the hydroxamate linker instead of the commonly used carboxylic acid linker will lead to a more efficient IET and better photon-to-current conversion efficiencies in Fe(II)-polypyridine sensitized solar cells. PMID:25767105

  3. Formation and phase transitions of methane hydrates under dynamic loadings: Compression rate dependent kinetics

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Yin; Yoo, Choong-Shik

    2012-03-01

    We describe high-pressure kinetic studies of the formation and phase transitions of methane hydrates (MH) under dynamic loading conditions, using a dynamic-diamond anvil cell (d-DAC) coupled with time-resolved confocal micro-Raman spectroscopy and high-speed microphotography. The time-resolved spectra and dynamic pressure responses exhibit profound compression-rate dependences associated with both the formation and the solid-solid phase transitions of MH-I to II and MH-II to III. Under dynamic loading conditions, MH forms only from super-compressed water and liquid methane in a narrow pressure range between 0.9 and 1.6 GPa at the one-dimensional (1D) growth rate of 42 μm/s. MH-I to II phase transition occurs at the onset of water solidification 0.9 GPa, following a diffusion controlled mechanism. We estimated the activation volume to be -109 ± 29 Å3, primarily associated with relatively slow methane diffusion which follows the rapid interfacial reconstruction, or martensitic displacements of atomic positions and hydrogen bonds, of 51262 water cages in MH-I to 4351263 cages in MH-II. MH-II to III transition, on the other hand, occurs over a broad pressure range between 1.5 and 2.2 GPa, following a reconstructive mechanism from super-compressed MH-II clathrates to a broken ice-filled viscoelastic solid of MH-III. It is found that the profound dynamic effects observed in the MH formation and phase transitions are primarily governed by the stability of water and ice phases at the relevant pressures.

  4. Formation and phase transitions of methane hydrates under dynamic loadings: compression rate dependent kinetics.

    PubMed

    Chen, Jing-Yin; Yoo, Choong-Shik

    2012-03-21

    We describe high-pressure kinetic studies of the formation and phase transitions of methane hydrates (MH) under dynamic loading conditions, using a dynamic-diamond anvil cell (d-DAC) coupled with time-resolved confocal micro-Raman spectroscopy and high-speed microphotography. The time-resolved spectra and dynamic pressure responses exhibit profound compression-rate dependences associated with both the formation and the solid-solid phase transitions of MH-I to II and MH-II to III. Under dynamic loading conditions, MH forms only from super-compressed water and liquid methane in a narrow pressure range between 0.9 and 1.6 GPa at the one-dimensional (1D) growth rate of 42 μm/s. MH-I to II phase transition occurs at the onset of water solidification 0.9 GPa, following a diffusion controlled mechanism. We estimated the activation volume to be -109±29 Å(3), primarily associated with relatively slow methane diffusion which follows the rapid interfacial reconstruction, or martensitic displacements of atomic positions and hydrogen bonds, of 5(12)6(2) water cages in MH-I to 4(3)5(12)6(3) cages in MH-II. MH-II to III transition, on the other hand, occurs over a broad pressure range between 1.5 and 2.2 GPa, following a reconstructive mechanism from super-compressed MH-II clathrates to a broken ice-filled viscoelastic solid of MH-III. It is found that the profound dynamic effects observed in the MH formation and phase transitions are primarily governed by the stability of water and ice phases at the relevant pressures. PMID:22443783

  5. Linker dependence of interfacial electron transfer rates in Fe(II)-polypyridine sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Bowman, David N.; Mukherjee, Sriparna; Barnes, Lyndsay J.; Jakubikova, Elena

    2015-04-01

    Dye-sensitized solar cells (DSSCs) convert solar energy to electricity employing dye molecules attached to a semiconductor surface. Some of the most efficient DSSCs use Ru-based chromophores. Fe-based dyes represent a cheaper and more environmentally friendly alternative to these expensive and toxic dyes. The photoactive state of Fe-based chromophores responsible for charge-separation at the dye-semiconductor interface is, however, deactivated on a sub-picosecond time scale via the intersystem crossing (ISC) into a manifold of low-lying photo-inactive quintet states. Therefore, development of Fe-based dyes capable of fast interfacial electron transfer (IET) leading to efficient charge separation on a time scale competitive with the ISC events is important. This work investigates how linker groups anchoring a prototypical Fe-based dye [Fe(bpy-L)2(CN)2] (bpy = 2,2‧-bipyridine, L = linker group) onto the TiO2 semiconductor surface influence the IET rates in the dye-semiconductor assemblies. Linker groups investigated include carboxylic acid, phosphonic acid, hydroxamate, catechol, and acetylacetonate. We employ time-dependent density functional theory (TD-DFT) to obtain absorption spectra of [Fe(bpy-L)2(CN)2] with each linker, and quantum dynamics simulations to investigate the IET rates between the dye and the (101) TiO2 anatase surface. For all attachments, TD-DFT calculations show similar absorption spectra with two main bands corresponding to the metal-to-ligand charge transfer transitions. The quantum dynamics simulations predict that the utilization of the hydroxamate linker instead of the commonly used carboxylic acid linker will lead to a more efficient IET and better photon-to-current conversion efficiencies in Fe(II)-polypyridine sensitized solar cells.

  6. Time-dependent energy transfer rates in a conjugated polymer guest-host system

    NASA Astrophysics Data System (ADS)

    Herz, L. M.; Silva, C.; Grimsdale, A. C.; Müllen, K.; Phillips, R. T.

    2004-10-01

    We have investigated the energy transfer dynamics in films of a conjugated polyindenofluorene host doped with covalently attached perylene guests. By performing time-resolved measurements of the host luminescence decay under site-selective excitation conditions, we have examined the influence of exciton migration within the host on the temporal evolution of the host-guest energy transfer. We find that highly mobile excitons created at the peak of the host’s inhomogeneous density of states transfer to guests considerably faster than more localized excitons created in the low-energy tail, indicating a strong contribution of exciton migration to the overall energy transfer. These effects are significantly more pronounced at low temperature (7K) than at ambient temperature, suggesting that for the latter, up-hill migration of excitons in the host and a broadening of their homogeneous linewidth may prevent truly site-selective excitation of localized excitons. In the asymptotic long-time limit, the observed dynamics are compatible with long-range single-step Förster energy transfer. However, at early times (≲10ps) after excitation, the behavior notably deviates from this description, suggesting that diffusion-assisted energy transfer is more important in this regime. The measured changes in excitation transfer rates with temperature and excitation energy correlate well with those observed for the dynamic energy shifts of the vibronic emission peaks from the undoped polymer. Our results therefore indicate that energy-transfer rates in polymeric guest-host systems are strongly time-dependent, owing to a contribution both from exciton relaxation through incoherent hopping within the host’s density of states and direct Förster energy transfer.

  7. Hatching Fish-When Should Animal Tracking Begin?

    PubMed

    Moulder, Gary L

    2016-07-01

    The National Institutes of Health: Final Report to Office of Laboratory Animal Welfare (OLAW) on Euthanasia of Zebrafish (2009) established for the first time a policy for the developmental stage at which zebrafish would qualify for animal oversight by OLAW interpretation of Public Health Service policy. This policy established the time point based on a comparison with chicken/avian hatching. For zebrafish, this is 3 days postfertilization (dpf). This is in contrast to the traditional time established within the community as 7 dpf. There are significant implications for this policy not the least of which is the demand to account for all embryo and larvae at all stages. This narrative provides a situational context based on a synthesis of real experience with this policy. The hope is that it provides a starting point for a community conversation on the hatching time point as the appropriate established policy for the future. PMID:27158771

  8. Rate dependent speech processing can be speech specific: Evidence from the perceptual disappearance of words under changes in context speech rate.

    PubMed

    Pitt, Mark A; Szostak, Christine; Dilley, Laura C

    2016-01-01

    The perception of reduced syllables, including function words, produced in casual speech can be made to disappear by slowing the rate at which surrounding words are spoken (Dilley & Pitt, Psychological Science, 21(11), 1664-1670. doi: 10.1177/0956797610384743 , 2010). The current study explored the domain generality of this speech-rate effect, asking whether it is induced by temporal information found only in speech. Stimuli were short word sequences (e.g., minor or child) appended to precursors that were clear speech, degraded speech (low-pass filtered or sinewave), or tone sequences, presented at a spoken rate and a slowed rate. Across three experiments, only precursors heard as intelligible speech generated a speech-rate effect (fewer reports of function words with a slowed context), suggesting that rate-dependent speech processing can be domain specific. PMID:26392395

  9. Dietary Arginine Requirements for Growth Are Dependent on the Rate of Citrulline Production in Mice123

    PubMed Central

    Marini, Juan C; Agarwal, Umang; Didelija, Inka C

    2015-01-01

    Background: In many species, including humans, arginine is considered a semiessential amino acid because under certain conditions endogenous synthesis cannot meet its demand. The requirements of arginine for growth in mice are ill defined and seem to vary depending on the genetic background of the mice. Objective: The objective of this study was to determine the metabolic and molecular basis for the requirement of arginine in 2 mouse strains. Methods: Institute of Cancer Research (ICR) and C57BL/6 (BL6) male mice were fed arginine-free or arginine-sufficient diets (Expt. 1) or 1 of 7 diets with increasing arginine concentration (from 0- to 8-g/kg diet, Expt. 2) between day 24 and 42 of life to determine the arginine requirements for growth. Citrulline production and “de novo” arginine synthesis were measured with use of stable isotopes, and arginine requirements were determined by breakpoint analysis and enzyme expression by reverse transcriptase-polymerase chain reaction. Results: In Expt. 1, ICR mice grew at the same rate regardless of the arginine concentration of the diet (mean ± SE: 0.66 ± 0.04 g/d, P = 0.80), but BL6 mice had a reduced growth rate when fed the arginine-free diet (0.25 ± 0.02 g/d, P < 0.001) compared to the 8-g arginine/kg diet (0.46 ± 0.03 g/d). ICR mice showed at least a 2-fold greater expression (P < 0.001) of ornithine transcarbamylase (OTC) than BL6 mice, which translated into a greater rate of citrulline (25%) and arginine synthesis (49%, P < 0.002). In Expt. 2, breakpoint analysis showed that the requirement for growth of BL6 mice was met with 2.32 ± 0.39 g arginine/kg diet; for ICR mice, however, no breakpoint was found. Conclusion: Our data indicate that a reduced expression of OTC in BL6 mice translates into a reduced production of citrulline and arginine compared with ICR mice, which results in a dietary arginine requirement for growth in BL6 mice, but not in ICR mice. PMID:25855119

  10. Language-Dependent Pitch Encoding Advantage in the Brainstem Is Not Limited to Acceleration Rates that Occur in Natural Speech

    ERIC Educational Resources Information Center

    Krishnan, Ananthanarayan; Gandour, Jackson T.; Smalt, Christopher J.; Bidelman, Gavin M.

    2010-01-01

    Experience-dependent enhancement of neural encoding of pitch in the auditory brainstem has been observed for only specific portions of native pitch contours exhibiting high rates of pitch acceleration, irrespective of speech or nonspeech contexts. This experiment allows us to determine whether this language-dependent advantage transfers to…

  11. Temperature dependences of growth rates and carrying capacities of marine bacteria depart from metabolic theoretical predictions.

    PubMed

    Huete-Stauffer, Tamara Megan; Arandia-Gorostidi, Nestor; Díaz-Pérez, Laura; Morán, Xosé Anxelu G

    2015-10-01

    Using the metabolic theory of ecology (MTE) framework, we evaluated over a whole annual cycle the monthly responses to temperature of the growth rates (μ) and carrying capacities (K) of heterotrophic bacterioplankton at a temperate coastal site. We used experimental incubations spanning 6ºC with bacterial physiological groups identified by flow cytometry according to membrane integrity (live), nucleic acid content (HNA and LNA) and respiratory activity (CTC+). The temperature dependence of μ at the exponential phase of growth was summarized by the activation energy (E), which was variable (-0.52 to 0.72 eV) but followed a seasonal pattern, only reaching the hypothesized value for aerobic heterotrophs of 0.65 eV during the spring bloom for the most active bacterial groups (live, HNA, CTC+). K (i.e. maximum experimental abundance) peaked at 4 × 10(6) cells mL(-1) and generally covaried with μ but, contrary to MTE predictions, it did not decrease consistently with temperature. In the case of live cells, the responses of μ and K to temperature were positively correlated and related to seasonal changes in substrate availability, indicating that the responses of bacteria to warming are far from homogeneous and poorly explained by MTE at our site. PMID:26362925

  12. GAMA/H-ATLAS: common star formation rate indicators and their dependence on galaxy physical parameters

    NASA Astrophysics Data System (ADS)

    Wang, L.; Norberg, P.; Gunawardhana, M. L. P.; Heinis, S.; Baldry, I. K.; Bland-Hawthorn, J.; Bourne, N.; Brough, S.; Brown, M. J. I.; Cluver, M. E.; Cooray, A.; da Cunha, E.; Driver, S. P.; Dunne, L.; Dye, S.; Eales, S.; Grootes, M. W.; Holwerda, B. W.; Hopkins, A. M.; Ibar, E.; Ivison, R.; Lacey, C.; Lara-Lopez, M. A.; Loveday, J.; Maddox, S. J.; Michałowski, M. J.; Oteo, I.; Owers, M. S.; Popescu, C. C.; Smith, D. J. B.; Taylor, E. N.; Tuffs, R. J.; van der Werf, P.

    2016-09-01

    We compare common star formation rate (SFR) indicators in the local Universe in the Galaxy and Mass Assembly (GAMA) equatorial fields (˜160 deg2), using ultraviolet (UV) photometry from GALEX, far-infrared and sub-millimetre (sub-mm) photometry from Herschel Astrophysical Terahertz Large Area Survey, and Hα spectroscopy from the GAMA survey. With a high-quality sample of 745 galaxies (median redshift = 0.08), we consider three SFR tracers: UV luminosity corrected for dust attenuation using the UV spectral slope β (SFRUV, corr), Hα line luminosity corrected for dust using the Balmer decrement (BD) (SFRH α, corr), and the combination of UV and infrared (IR) emission (SFRUV + IR). We demonstrate that SFRUV, corr can be reconciled with the other two tracers after applying attenuation corrections by calibrating Infrared excess (IRX; i.e. the IR to UV luminosity ratio) and attenuation in the Hα (derived from BD) against β. However, β, on its own, is very unlikely to be a reliable attenuation indicator. We find that attenuation correction factors depend on parameters such as stellar mass (M*), z and dust temperature (Tdust), but not on Hα equivalent width or Sérsic index. Due to the large scatter in the IRX versus β correlation, when compared to SFRUV + IR, the β-corrected SFRUV, corr exhibits systematic deviations as a function of IRX, BD and Tdust.

  13. Earthquake Nucleation on Faults with a Revised Rate- and State-Dependent Friction Law

    NASA Astrophysics Data System (ADS)

    Kame, Nobuki; Fujita, Satoshi; Nakatani, Masao; Kusakabe, Tetsuya

    2015-08-01

    Recently N agata et al. (J Geophys Res 117:B02314, 2012) have proposed a new version of rate- and state-dependent friction law (RSF) that seems to have eventually resolved all the previously known discrepancies in the existing RSFs from laboratory observations. The values of a and b, empirical RSF parameters determined by fitting the same laboratory experiments, have been revised to be five times greater and a newly noticed weakening effect by shear stress with a coefficient c has been introduced. By using this revised RSF, we reinvestigated a problem of 2D quasi-static nucleation on faults. A crack-like nucleation-zone expansion known for the `aging' version of RSF is not sustainable with the `Nagata' law, which is understandable as the Nagata law does not produce a slip-weakening distance proportional to the involved strength reduction, an aging law's feature that contradicts laboratory observations. The later stage of Nagata-law nucleation shows localization of quasi-static slip within a limited spatial extent, but the localization is much milder than that predicted by the `slip' version of RSF. With an appropriate c parameter of the Nagata law, the nucleation size seems to be reduced only by a factor from that of the aging law.

  14. Effect of rate-dependent left bundle branch block on global and regional left ventricular function

    SciTech Connect

    Bramlet, D.A.; Morris, K.G.; Coleman, R.E.; Albert, D.; Cobb, F.R.

    1983-05-01

    Seven subjects with rate-dependent left bundle branch block (RDLBBB) and 13 subjects with normal conduction (control group) underwent upright bicycle exercise radionuclide angiography to determine the effects of the development of RDLBBB on global and regional left ventricular function. Six of the seven subjects with RDLBBB had atypical chest pain syndromes; none had evidence of cardiac disease based on clinical examination and either normal cardiac catheterization or exercise thallium-201 scintigraphy. Radionuclide angiograms were recorded at rest and immediately before and after RDLBBB in the test group, and at rest and during intermediate and maximal exercise in the control group. The development of RDLBBB was associated with an abrupt decrease in left ventricular ejection fraction (LVEF) in six of seven patients (mean decrease 6 +/- 5%) and no overall increase in LVEF between rest and maximal exercise (65 +/- 9% and 65 +/- 12%, respectively). In contrast, LVEF in the control group was 62 +/- 8% at rest and increased to 72 +/- 8% at intermediate and 78 +/- 7% at maximal exercise. The onset of RDLBBB was associated with the development of asynchronous left ventricular contraction in each patient and hypokinesis in four of seven patients. All patients in the control group had normal wall motion at rest and exercise. These data indicate that the development of RDLBBB is associated with changes in global and regional ventricular function that may be confused with development of left ventricular ischemia during exercise.

  15. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Technical Reports Server (NTRS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-01-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

  16. Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

    NASA Astrophysics Data System (ADS)

    Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

    1994-08-01

    Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by intrduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spaceflight, and show that extensive degress of development can take place in this microgravity environment.

  17. Hatching failure increases with severity of population bottlenecks in birds

    PubMed Central

    Briskie, James V.; Mackintosh, Myles

    2004-01-01

    Severe bottlenecks can reduce genetic diversity and increase inbreeding as individuals are forced to mate with close relatives, but it is unknown at what minimum population size the negative fitness consequences of bottlenecks are expressed. The New Zealand avifauna contains a large number of species that have gone through bottlenecks of varying severity, providing an exceptional opportunity to test this question by using the comparative method. Using decreased hatchability as a measure of fitness costs, we found that hatching failure was significantly greater among both native and introduced species that had passed through bottlenecks of <150 individuals. Comparisons between pre- and postbottleneck populations of introduced species suggest that hatching problems arise even in populations founded by <600 individuals. Our study confirms that hatching failure is widespread and persistent among birds passing through severe bottlenecks and that the population sizes at which this fitness cost is expressed are several times greater than the number of individuals currently used to found most new populations of endangered species. We recommend that conservation managers revise the protocols they use for reintroductions or they may unwittingly reduce the long-term viability of the species they are trying to save. PMID:14699045

  18. Inheritance and World Variation in Thermal Requirements for Egg Hatch in Lymantria dispar (Lepidoptera: Erebidae).

    PubMed

    Keena, M A

    2016-02-01

    Mode of inheritance of hatch traits in Lymantria dispar L. was determined by crossing populations nearly fixed for the phenotypic extremes. The nondiapausing phenotype was inherited via a single recessive gene and the phenotype with reduced low temperature exposure requirements before hatch was inherited via a single dominant gene. There was no evidence for sex-linkage or cytoplasmic effects with either gene. Eggs from 43 geographic populations were evaluated for hatch characteristics after being held for 60 d at 5°C followed by incubation at 25°C. There was considerable variation both within and among the populations in the proportion able to hatch, time to first hatch, and average time to hatch. Egg masses with reduced requirement for low temperatures before the eggs were ready to hatch were present in all subspecies of L. dispar and the phenotype was not fixed in most populations. The populations clustered into three distinct groups, and climatic variables were found to be rough predictors of those groups. Variation in hatch phenotypes between populations is likely an adaptation to local climate and within a population provides a bet-hedging strategy to ensure that at least some hatch synchronizes with host leaf-out. Continued vigilance to prevent movement of populations both within and between countries is warranted, because some of the alleles that confer nondiapause or reduced low temperature requirements before egg hatch are not present in all populations and their introduction would increase variation in egg hatch within a population. PMID:26510608

  19. Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

    SciTech Connect

    Horn, Kevin M.

    2013-07-09

    A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

  20. Effects of Al/Si ordering on feldspar dissolution: Part II. The pH dependence of plagioclases' dissolution rates

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Min, Yujia; Jun, Young-Shin

    2014-02-01

    The rate of mineral dissolution in an aquatic environment is sensitive to the pH of the contacting solution. The pH dependence of mineral dissolution rate has been interpreted by the Transition State Theory-Surface Complexation Model (TST-SCM) formalism in terms of pH-sensitive variability in surface chemistry. In this study, we provide an alternative interpretation for the experimentally observed nonlinear pH dependence of feldspar dissolution rates. The interpretation is based on a new formalism for feldspar dissolution which, while compatible with the TST-SCM formalism, incorporates the effects of both surface chemistry and bulk chemistry on feldspar dissolution into the quantification of dissolution rate. The pH dependence of dissolution rate varies from one feldspar specimen to another because different TOT linkages within one solid matrix can respond differently to the attack of proton. Our results suggest that the pH dependence of feldspar dissolution rate is not a constant in general, and could be affected by pH, substitutional Al/Si ordering, chemical composition of the specimen, and the relative rapidness of linkage hydrolysis according to different mechanisms. The rate law proposed in this study is able to capture the experimentally observed pH dependence of the dissolution rates of a series of plagioclases, including albite, andesine, labradorite, bytownite, and anorthite. The effectiveness of the newly proposed formalism for feldspar dissolution, hence, suggests that dissolution reactions of minerals are combinations of surface renewal and heterogeneous chemical reactions. The currently widely used TST-SCM-based rate laws can be further improved by taking into account the effects of bulk chemistry and surface renewal in the prediction of mineral dissolution rates. An improved formalism for mineral dissolution will be mineral-specific, and will reflect the effects of the temporal decay in the availability of reactive surface sites as well as the