bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of quantum dot filling on dual-band optical transitions via intermediate quantum states
Authors: Wu Jiang , Passmore Brandon , Manasreh M. O.
Published: August 2015

InAs/GaAs quantum dot infrared photodetectors with different doping levels were investigated to understand the effect of quantum dot filling on both intraband and interband optical transitions. The electron filling of self-assembled InAs quantum dots was varied by direct doping of quantum dots with different concentrations. Photoresponse in the near infrared and middle wavelength infrared spectral region was observed from samples with low quantum dot filling. Although undoped quantum dots were favored for interband transitions with the absence of a second optical excitation in the near infrared region, doped quantum dots were preferred to improve intraband transitions in the middle wavelength infrared region. As a result, partial filling of quantum dot was required, to the extent of maintaining a low dark current, to enhance the dual-band photoresponse through the confined electron states.
Degradation mechanisms of 2 MeV proton irradiated AlGaN/GaN HEMTs
Authors: Greenlee Jordan D. , Specht Petra , Anderson Travis J. , Koehler Andrew D. , Weaver Bradley D. , Luysberg Martina , Dubon Oscar D. , Kub Francis J. , Weatherford Todd R. , Hobart Karl D.
Published: August 2015

Proton-induced damage in AlGaN/GaN HEMTs was investigated using energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM), and simulated using a Monte Carlo technique. The results were correlated to electrical degradation using Hall measurements. It was determined by EDS that the interface between GaN and AlGaN in the irradiated HEMT was broadened by 2.2 nm, as estimated by the width of the Al EDS signal compared to the as-grown interface. The simulation results show a similar Al broadening effect. The extent of interfacial roughening was examined using high resolution TEM. At a 2 MeV proton fluence of 6 × 1014 H+/cm2, the electrical effects associated with the Al broadening and surface roughening include a degradation of the ON-resistance and a decrease in the electron mobility and 2DEG sheet carrier density by 28.9% and 12.1%, respectively.
Mid-infrared silicon-on-sapphire waveguide coupled photonic crystal microcavities
Authors: Zou Yi , Chakravarty Swapnajit , Chen Ray T.
Published: August 2015

We experimentally demonstrate a photonic crystal (PC) microcavity side coupled to a W1.05 photonic crystal waveguide fabricated in silicon-on-sapphire working in mid-IR regime at 3.43 μm. Using a fixed wavelength laser source, propagation characteristics of PC waveguides without microcavity are characterized as a function of lattice constant to determine the light line position, stop gap, and guided mode transmission behavior. The resonance of an L21 PC microcavity coupled to the W1.05 PCW in the guided mode transmission region is then measured by thermal tuning of the cavity resonance across the source wavelength. Resonance quality factor ∼3500 is measured from the temperature dependency curve.
Plasmon-induced dynamics of H2 splitting on a silver atomic chain
Authors: Yan Lei , Ding Zijing , Song Peng , Wang Fangwei , Meng Sheng
Published: August 2015

Localized surface plasmon resonances (LSPR) supported in metal nanostructures can be efficiently harnessed to drive photocatalytic reactions, whose atomic scale mechanism remains a challenge. Here, real-time dynamics of H2 photosplitting on a linear silver atomic chain, upon exposure to femtosecond laser pulses, has been investigated using time-dependent density functional theory. The wavelength dependent H2 splitting process is strongly coupled to LSPR excitation in silver chain. We identify that hot electrons produced in the silver chain by plasmon excitation are transferred to the antibonding state of the adsorbed H2 and trigger H2 dissociation, consistent with experimental observations. Increasing illumination intensity and the length of atomic chain promote H2 splitting, thanks to stronger LSPR. Dynamic electronic response can be quantitatively described within the present approach, providing insights towards a complete fundamental understanding on plasmon-induced chemical reactions at the microscopic scale.
Enhanced electromechanical properties and phase transition temperatures in [001] textured Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 ternary ceramics
Authors: Chang Yunfei , Wu Jie , Sun Yuan , Zhang Shantao , Wang Xiaohui , Yang Bin , Messing Gary L. , Cao Wenwu
Published: August 2015

[001] oriented relaxor based ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) ceramics were fabricated by templated grain growth. The effects of BaTiO3 template amount on the [001] orientation degree, microstructure, and resulting changes in dielectric, piezoelectric, and ferroelectric properties of PIN-PMN-PT were investigated. A high [001] texture fraction of 93% was achieved in the PIN-PMN-PT ceramics at 5 vol. % BaTiO3 template. Giant electromechanical properties (d33* = 1555 pC/N, d33 = 824 pC/N, and kp = 0.81) and high ferroelectric properties (Ec = 8.3 kV/cm and Pr = 31 μC/cm2) were obtained from those highly textured ceramics, which are much superior to those of randomly oriented counterpart. Furthermore, the textured ternary ceramics exhibited remarkably improved phase transition temperatures (Tr-t = 120 °C and Tc = 203 °C) compared with previously reported binary PMN-PT textured ceramics. The domain structure was characterized by piezoelectric force microscopy, and domain contribution to the enhanced piezoelectric response in the textured PIN-PMN-PT ceramics was analyzed. The high-quality textured ternary ceramics are very promising for new-generation electromechanical devices with high performance and wide temperature usage range.
Note: A disposable x-ray camera based on mass produced complementary metal-oxide-semiconductor sensors and single-board computers
Authors: Hoidn Oliver R. , Seidler Gerald T.
Published: August 2015

We have integrated mass-produced commercial complementary metal-oxide-semiconductor (CMOS) image sensors and off-the-shelf single-board computers into an x-ray camera platform optimized for acquisition of x-ray spectra and radiographs at energies of 2–6 keV. The CMOS sensor and single-board computer are complemented by custom mounting and interface hardware that can be easily acquired from rapid prototyping services. For single-pixel detection events, i.e., events where the deposited energy from one photon is substantially localized in a single pixel, we establish ∼20% quantum efficiency at 2.6 keV with ∼190 eV resolution and a 100 kHz maximum detection rate. The detector platform’s useful intrinsic energy resolution, 5-μm pixel size, ease of use, and obvious potential for parallelization make it a promising candidate for many applications at synchrotron facilities, in laser-heating plasma physics studies, and in laboratory-based x-ray spectrometry.
Validation of the PHQ-2 against the PHQ-9 for detecting depression in a large sample of Australian general practice patients
Authors: Carey Mariko , Boyes Allison , Noble Natasha , Waller Amy , Inder Kerry
Published: August 2015

There is increasing interest in the use of brief screening tools to improve detection of depression in the primary care setting. The aim of the present study was to compare the accuracy of the two-item Patient Health Questionnaire (PHQ-2) against the nine-item Patient Health Questionnaire (PHQ-9) for detecting depression among general practice patients. A cross-sectional sample of 3626 adults attending 12 Australian general practices was recruited. Participants completed the PHQ-2 and PHQ-9 via a touchscreen computer. Depression was defined as a PHQ-9 score ≥10. The area under the curve (AUC), sensitivity, specificity, positive predictive value and negative predictive value were calculated. The PHQ-2 had good overall accuracy relative to the PHQ-9 for discriminating between cases and non-cases of depression, with an AUC of 0.92 (95% confidence interval 0.90–0.93). The PHQ-2 threshold of ≥3 was the best balance between sensitivity (91%) and specificity (78%) for detecting possible cases of depression. For clinical use, the optimal threshold was ≥2, with only 2% of possible cases missed.
Revisiting the ability of Australian primary healthcare services to respond to health inequity
Authors: Freeman Toby , Baum Fran , Lawless Angela , Javanparast Sara , Jolley Gwyn , Labonté Ronald , Bentley Michael , Boffa John , Sanders David
Published: August 2015

Equity of access and reducing health inequities are key objectives of comprehensive primary health care. However, the supports required to target equity are fragile and vulnerable to changes in the fiscal and political environment. Six Australian primary healthcare services, five in South Australia and one in the Northern Territory, were followed over 5 years (2009–2013) of considerable change. Fifty-five interviews were conducted with service managers, staff, regional health executives and health department representatives in 2013 to examine how the changes had affected their practice regarding equity of access and responding to health inequity. At the four state government services, seven of 10 previously identified strategies for equity of access and services’ scope to facilitate access to other health services and to act on the social determinants of health inequity were now compromised or reduced in some way as a result of the changing policy environment. There was a mix of positive and negative changes at the non-government organisation. The community-controlled service increased their breadth of strategies used to address health equity. These different trajectories suggest the value of community governance, and highlight the need to monitor equity performance and advocate for the importance of health equity.
Subset of early radial glial progenitors that contribute to the development of callosal neurons is absent from avian brain
Authors: García-Moreno Fernando , Molnár Zoltán
Published: August 2015

Significance

Understanding development and evolution of the neocortex has important implications. We describe here a major difference between avian and mammalian dorsal pallial progenitors regarding their fate restrictions. In mouse cortex we identified an early population of radial glial cells that are delayed in the generation of neurons. After self-renewal and transit-amplifying mitoses, these murine progenitors become committed to the genesis of upper-layer callosal pyramidal neurons and glia. In the chick embryonic pallium we identified a homologous population of progenitors; however, these have no delayed neurogenesis and their lineage is therefore not segregated from that of the other pallial progenitors. We hypothesize on the relation between the early neurogenic delay of progenitors and the origin of the corpus callosum.
Transcription factor p63 controls the reserve status but not the stemness of horizontal basal cells in the olfactory epithelium
Authors: Schnittke Nikolai , Herrick Daniel B. , Lin Brian , Peterson Jesse , Coleman Julie H. , Packard Adam I. , Jang Woochan , Schwob James E.
Published: August 2015

Significance

Harnessing the inherent capability of stem cells to maintain and regenerate injured tissues is a prerequisite for their use in mending damage to the nervous system. In the olfactory epithelium stem cells accomplish neurogenesis and epithelial repair throughout life to an extent not seen elsewhere in the nervous system. Here we show that the transcription factor protein 63 (
p63
) is a master regulator of the transition from the reserve to the active stem cell pool in the epithelium. Loss of
p63
expression in reserve basal cells is necessary and sufficient for activation, without compromising stem cell status. Identification of this central mechanism provides a target for stem cell activation in this uniquely accessible source of patient-specific, neurogenic stem cells.
Admissions to Detoxification after Treatment: Does Engagement Make a Difference?
Authors: Acevedo Andrea , Garnick Deborah , Ritter Grant , Lundgren Lena , Horgan Constance
Published: August 2015

Background

Treatment engagement is a well-established performance measure for the treatment of substance use disorders. This study examined whether outpatient treatment engagement is associated with a reduced likelihood of subsequent detoxification admissions.

Methods

This study used administrative data on treatment services received by clients in specialty treatment facilities licensed in Massachusetts. The sample consisted of 11,591 adult clients who began an outpatient treatment episode in 2006. Treatment engagement was defined as receipt of at least 1 treatment service within 14 days of beginning a new outpatient treatment episode and receipt of at least 2 additional treatment services in the next 30 days. The outcome was a subsequent detoxification admission. Multilevel survival models examined the relationship between engagement and outcomes, with time to detoxification admission as the dependent variable censored at 365 days.

Results

Only 35% of clients met the outpatient engagement criteria, and 15% of clients had a detoxification admission within a year after beginning their outpatient treatment episode. Controlling for client demographics, insurance type, and substance use severity, clients who met the engagement criteria had a lower hazard of having a detoxification admission during the year following the index outpatient visit than those who did not engage (hazard ratio = 0.87, P < .01).

Conclusions

Treatment engagement is a useful measure for monitoring quality of care. The findings from this study could help inform providers and policy makers on ways to target care and reduce the likelihood of more intensive services.
Multispecialty Screening, Brief Intervention, and Referral to Treatment (SBIRT) Training in An Academic Medical Center: Resident Training Experience across Specialties
Authors: Clemence A. Jill , Balkoski Victoria I. , Schaefer Bianca M. , Lee Minsun , Bromley Nicole , Maisonneuve Isabelle M. , Hamilton Christopher J. , Lukowitsky Mark R. , Poston John , Hall Schekeva , Pieterse Portia , Antonikowski Angela , Glick Stanley D.
Published: August 2015

Background

The Substance Abuse and Mental Health Services Administration (SAMHSA) has recently begun to fund programs that train medical residents on how to utilize an evidence-based validated system known as screening, brief intervention, and referral to treatment (SBIRT) for providing early detection and brief treatment of unhealthy substance use. This paper investigates training outcomes of multispecialty SBIRT training at one such program at Albany Medical Center (AMC), one of the initial SAMHSA grantees.

Methods

Training outcomes were measured across 3 domains of learning: trainee satisfaction, acquired knowledge, and perceived usefulness. The authors explored differences in learning experience by postgraduate year and by specialty.

Results

Overall, residents were highly satisfied with the training, and learning outcomes met objectives. Residents’ ratings of usefulness did not vary by program year. However, the results indicate that relative to residents in other programs, residents in psychiatry and pediatrics found the training components significantly more useful, whereas emergency medicine residents found training components to have less utility. Residents who found the training relevant to their daily work were more satisfied and more receptive to SBIRT training overall, which may help explain difference scores by program.

Conclusions

Residents were highly satisfied with SBIRT skills training, although ratings of usefulness varied by residency program. Specialization by program and on-site modeling by senior faculty may enhance trainee satisfaction and perceived usefulness.
SODAS: Surveillance of Drugs of Abuse Study
Authors: Lowe David J. , Torrance Hazel J. , Ireland Alastair J. , Bloeck Felix , Stevenson Richard
Published: August 2015

Objective

Novel psychoactive substance (NPS) as a form of recreational drug use has become increasingly popular. There is a paucity of information with regard to the prevalence and clinical sequelae of these drugs. The aim of this study was to detect NPS in patients presenting to the emergency department with suspected toxicological ingestion.

Patients and methods

The prospective study was performed in a large emergency department in the UK. During a 3-month period 80 patients were identified by clinicians as having potentially ingested a toxicological agent. Urine samples were analysed using liquid chromatography high-resolution mass spectrometry, and basic clinical data was gathered.

Results

Eighty patients with a history of illicit or recreational drug consumption had urine screenings performed. Forty-nine per cent (39) of the patients undergoing a screen had more than one illicit substance detected. Twenty per cent (16) of the patients tested positive for at least one NPS.

Conclusion

Almost half of the presented patients revealed ingestion of multiple substances, which correlated poorly with self-reporting of patients. Developing enhanced strategies to monitor evolving drug trends is crucial to the ability of clinicians to deliver care to this challenging group of patients.
Number of organ dysfunctions predicts mortality in emergency department patients with suspected infection: a multicenter validation study
Authors: Jessen Marie K. , Skibsted Simon , Shapiro Nathan I.
Published: August 2015

Objectives

The aim of this study was to validate the association between number of organ dysfunctions and mortality in emergency department (ED) patients with suspected infection.

Methods

This study was conducted at two medical care center EDs. The internal validation set was a prospective cohort study conducted in Boston, USA. The external validation set was a retrospective case–control study conducted in Aarhus, Denmark. The study included adult patients (>18 years) with clinically suspected infection. Laboratory results and clinical data were used to assess organ dysfunctions. Inhospital mortality was the outcome measure. Multivariate logistic regression was used to determine the independent mortality odds for number and types of organ dysfunctions.

Results

We enrolled 4952 (internal) and 483 (external) patients. The mortality rate significantly increased with increasing number of organ dysfunctions: internal validation: 0 organ dysfunctions: 0.5% mortality, 1: 3.6%, 2: 9.5%, 3: 17%, and 4 or more: 37%; external validation: 2.2, 6.7, 17, 41, and 57% mortality (both P<0.001 for trend). Age-adjusted and comorbidity-adjusted number of organ dysfunctions remained an independent predictor. The effect of specific types of organ dysfunction on mortality was most pronounced for hematologic [odds ratio (OR) 3.3 (95% confidence interval (CI) 2.0–5.4)], metabolic [OR 3.3 (95% CI 2.4–4.6); internal validation], and cardiovascular dysfunctions [OR 14 (95% CI 3.7–50); external validation].

Conclusion

The number of organ dysfunctions predicts sepsis mortality.
Tranexamic acid in major trauma: implementation and evaluation across South West England
Authors: Paudyal Priyamvada , Smith Jason , Robinson Maria , South Adrian , Higginson Ian , Reuben Adam , Shaffee Julian , Black Sarah , Logan Stuart
Published: August 2015

Objective

To carry out a prospective evaluation of tranexamic acid (TXA) use in trauma patients.

Patients and methods

TXA was introduced to all emergency ambulances and emergency departments in the South West, UK, on 1 December 2011. We carried out a prospective evaluation of TXA use in trauma patients in the South West Peninsula between December 2011 and December 2012. We collected prehospital and hospital data on TXA administration using the Trauma Audit Research Network database. Data on prehospital administration of TXA were cross-checked with the South Western Ambulance Service Trust. Data were analysed using SPSS (version 20).

Results

Altogether, 82 patients were administered TXA during the study period. The median age of the patients was 49 years (IQR 30, 66), and 72% were men. One-third of the patients arrived at hospital by air ambulance. During the first 3 months, administration of TXA was limited to one patient each month receiving the drug. However, an upward trend was observed after June until October 2012, with the increment being more than 10 fold in July, September and October 2012.

Conclusion

This is the first study to evaluate the use of TXA in civilian practice in the UK. Our study shows that ambulance service personnel and emergency departments can effectively administer TXA.
Discovery of Xuebijing Injection Exhibiting Protective Efficacy on Sepsis by Inhibiting the Expression of HMGB1 in Septic Rat Model Designed by Cecal Ligation and Puncture
Authors: Chen Shengguang , Dai Guoxing , Hu Jiawen , Rong Aihong , Lv Jie , Su Lijie , Wu Xianzheng
Published: August 2015

Xuebijing (XBJ) injection is a complex traditional Chinese prescription that has been widely used to treat sepsis in China. However, its underlying mechanisms on sepsis still remain uninvestigated. In this study, 150 male Sprague Dawley rats were randomly divided into a normal control group, cecal ligation and puncture (CLP) group, CLP+XBJ group, and CLP+gibberellic acid group. Each of them contained 3 subgroups of different treatment periods (12, 24, and 48 hours after injection, respectively). The mRNA expression of HMGB1 in liver tissue of the 4 groups was calculated by the semiquantitative reverse-transcription polymerase chain reaction. The level of IL-6, IL-10, and TNF-α was determined by an enzyme-linked immunosorbent assay. Immunohistochemical analysis for HMGB1 showed the effect of XBJ on infiltration of inflammatory cells. The mRNA expression of HMGB1 in liver tissue in CLP+XBJ and CLP+gibberellic acid groups was lower than that in the CLP group. The levels of IL-6, IL-10, and TNF-α were decreased at the each monitored time point. All these results indicated that XBJ exhibits protective efficacy on sepsis by inhibiting the expression of HMGB1.
Presence of cleaner wrasse increases the recruitment of damselfishes to coral reefs
Authors: Sun Derek , Cheney Karen L. , Werminghausen Johanna , Meekan Mark G. , McCormick Mark I. , Cribb Thomas H. , Grutter Alexandra S.
Published: August 2015

Mutualisms affect the biodiversity, distribution and abundance of biological communities. However, ecological processes that drive mutualism-related shifts in population structure are often unclear and must be examined to elucidate how complex, multi-species mutualistic networks are formed and structured. In this study, we investigated how the presence of key marine mutualistic partners can drive the organisation of local communities on coral reefs. The cleaner wrasse,
Labroides dimidiatus
, removes ectoparasites and reduces stress hormones for multiple reef fish species, and their presence on coral reefs increases fish abundance and diversity. Such changes in population structure could be driven by increased recruitment of larval fish at settlement, or by post-settlement processes such as modified levels of migration or predation. We conducted a controlled field experiment to examine the effect of cleaners on recruitment processes of a common group of reef fishes, and showed that small patch reefs (61–285 m
2
) with cleaner wrasse had higher abundances of damselfish recruits than reefs from which cleaner wrasse had been removed over a 12-year period. However, the presence of cleaner wrasse did not affect species diversity of damselfish recruits. Our study provides evidence of the ecological processes that underpin changes in local population structure in the presence of a key mutualistic partner.
Escaping peril: perceived predation risk affects migratory propensity
Authors: Hulthén Kaj , Chapman Ben B. , Nilsson P. Anders , Vinterstare Jerker , Hansson Lars-Anders , Skov Christian , Brodersen Jakob , Baktoft Henrik , Brönmark Christer
Published: August 2015

Although migratory plasticity is increasingly documented, the ecological drivers of plasticity are not well understood. Predation risk can influence migratory dynamics, but whether seasonal migrants can adjust their migratory behaviour according to perceived risk is unknown. We used electronic tags to record the migration of individual roach (Rutilus rutilus), a partially migratory fish, in the wild following exposure to manipulation of direct (predator presence/absence) and indirect (high/low roach density) perceived predation risk in experimental mesocosms. Following exposure, we released fish in their lake summer habitat and monitored individual migration to connected streams over an entire season. Individuals exposed to increased perceived direct predation risk (i.e. a live predator) showed a higher migratory propensity but no change in migratory timing, while indirect risk (i.e. roach density) affected timing but not propensity showing that elevated risk carried over to alter migratory behaviour in the wild. Our key finding demonstrates predator-driven migratory plasticity, highlighting the powerful role of predation risk for migratory decision-making and dynamics.
Sex-specific maternal effects in a viviparous fish
Authors: Kruuk Loeske E. B. , Livingston Julianne , Kahn Andrew , Jennions Michael D.
Published: August 2015

Mothers vary in their effects on their offspring, but studies of variation in maternal effects rarely ask whether differences between mothers are consistent for sons and daughters. Here, we analysed maternal effects in the mosquitofish
Gambusia holbrooki
for development time and adult size of sons and daughters, and a primary male sexual character (gonopodium length). We found substantial maternal effects on all traits, most notably for gonopodium length. There were significant correlations within each sex for maternal effects on different traits, indicative of trade-offs between development rate and adult size. By contrast, there was no evidence of any consistency in maternal effects on sons and daughters. This suggests that the evolution of maternal effects will follow independent trajectories dependent on sex-specific selection on offspring. Importantly, failure to recognize the sex-specific nature of maternal effects in this population would have substantially underestimated the extent of their variation between mothers.
Stressful colours: corticosterone concentrations in a free-living songbird vary with the spectral composition of experimental illumination
Authors: Ouyang Jenny Q. , de Jong Maaike , Hau Michaela , Visser Marcel E. , van Grunsven Roy H. A. , Spoelstra Kamiel
Published: August 2015

Organisms have evolved under natural daily light/dark cycles for millions of years. These cycles have been disturbed as night-time darkness is increasingly replaced by artificial illumination. Investigating the physiological consequences of free-living organisms in artificially lit environments is crucial to determine whether nocturnal lighting disrupts circadian rhythms, changes behaviour, reduces fitness and ultimately affects population numbers. We make use of a unique, large-scale network of replicated field sites which were experimentally illuminated at night using lampposts emanating either red, green, white or no light to test effect on stress hormone concentrations (corticosterone) in a songbird, the great tit (
Parus major
). Adults nesting in white-light transects had higher corticosterone concentrations than in the other treatments. We also found a significant interaction between distance to the closest lamppost and treatment type: individuals in red light had higher corticosterone levels when they nested closer to the lamppost than individuals nesting farther away, a decline not observed in the green or dark treatment. Individuals with high corticosterone levels had fewer fledglings, irrespective of treatment. These results show that artificial light can induce changes in individual hormonal phenotype. As these effects vary considerably with light spectrum, it opens the possibility to mitigate these effects by selecting street lighting of specific spectra.
All the better to see you with: eyes and claws reveal the evolution of divergent ecological roles in giant pterygotid eurypterids
Authors: McCoy Victoria E. , Lamsdell James C. , Poschmann Markus , Anderson Ross P. , Briggs Derek E. G.
Published: August 2015

Pterygotid eurypterids have traditionally been interpreted as active, high-level, visual predators; however, recent studies of the visual system and cheliceral morphology of the pterygotidAcutiramuscontradict this interpretation. Here, we report similar analyses of the pterygotidsErettopterus, JaekelopterusandPterygotus, and the pterygotid sister taxonSlimonia. Representative species of all these genera have more acute vision thanA. cummingsi. The visual systems ofJaekelopterus rhenaniaeandPterygotus anglicusare comparable to that of modern predatory arthropods. All species ofJaekelopterusandPterygotushave robust crushing chelicerae, morphologically distinct from the weaker slicing chelicerae ofAcutiramus. Vision inErettopterus osiliensisandSlimonia acuminatais more acute than inAcutiramus cummingsi, but not to the same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function. The pterygotids evolved with a shift in ecology from generalized feeder to specialized predator. Pterygotid eurypterids share a characteristic morphology but, although some were top predators, their ecology differs radically between genera.
Rodney Hill. 11 June 1921 — 2 February 2011
Authors: Sewell Michael J.
Published: August 2015

Rodney Hill was born on 11 June 1921 in Leeds, and educated at Leeds Grammar School. He went up to Cambridge University in October 1939, with a Major Scholarship at Pembroke College. He graduated BA with first-class honours in 1942 in the Mathematical Tripos. Volunteering for war work immediately, he worked in full-time government service on ballistics in the Cambridge Mathematical Laboratory, and on the plasticity of metals in the Cavendish Laboratory. In 1943 he moved to the Armament Research Department at Fort Halstead in Kent, for three years. Here he was involved in, for example, the modelling of armour penetration by projectiles. This established his expertise in the Mathematical Theory of Plasticity, in which he became a world-recognized leader via the writing of a renowned book with that title (still in print after 60 years) and 170 research articles with eventually 26 collaborators. He had more than 10 research students. In 1963 he wrote a textbook,
Principles of dynamics
, based on his lectures to undergraduates. Subsequent appointments were at the British Iron and Steel Research Association in Sheffield, at Bristol University, and then as Professor of Applied Mathematics at Nottingham University (1953–62), and at Cambridge University. He retired in 1979 but continued with active research for more than another 20 years. Hill was elected a Fellow of the Royal Society in 1961, whose Royal Medal he received in 1993. He received the Honorary Degree of DSc from the Universities of Manchester (1976) and Bath (1978). He was awarded the von Karman Medal of the American Society of Civil Engineers in 1978, and the Panetti Medal of the Turin Academy in 1988. In 1982 The Rodney Hill 60th Anniversary Volume called
Mechanics of solids
was published, edited by H. G. Hopkins and M. J. Sewell. It contains 19 articles by 23 contributors in 693 pages. The Rodney Hill Prize in Solid Mechanics (US $25 000, at four-yearly intervals) has been established by Elsevier Ltd. It was awarded first in 2008 (Ortiz) and then in 2012 (Gao). A principal relaxation of Hill for 50 years was in extended botanical expeditions with his wife, Jeanne, in many parts of the English countryside, searching for, and identifying and recording, many species of wild flowers and fungi; and in the cultivation of a garden at home. Rodney Hill married Jeanne Wickens in 1945. She died in 2003. They had one daughter, Caroline, who survives them. Rodney died in Cambridge on 2 February 2011.
Cavitation inception from bubble nuclei
Authors: Mørch K. A.
Published: August 2015

The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure–time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes.
Modelling cavitation erosion using fluid–material interaction simulations
Authors: Chahine Georges L. , Hsiao Chao-Tsung
Published: August 2015

Material deformation and pitting from cavitation bubble collapse is investigated using fluid and material dynamics and their interaction. In the fluid, a novel hybrid approach, which links a boundary element method and a compressible finite difference method, is used to capture non-spherical bubble dynamics and resulting liquid pressures efficiently and accurately. The bubble dynamics is intimately coupled with a finite-element structure model to enable fluid/structure interaction simulations. Bubble collapse loads the material with high impulsive pressures, which result from shock waves and bubble re-entrant jet direct impact on the material surface. The shock wave loading can be from the re-entrant jet impact on the opposite side of the bubble, the fast primary collapse of the bubble, and/or the collapse of the remaining bubble ring. This produces high stress waves, which propagate inside the material, cause deformation, and eventually failure. A permanent deformation or pit is formed when the local equivalent stresses exceed the material yield stress. The pressure loading depends on bubble dynamics parameters such as the size of the bubble at its maximum volume, the bubble standoff distance from the material wall and the pressure driving the bubble collapse. The effects of standoff and material type on the pressure loading and resulting pit formation are highlighted and the effects of bubble interaction on pressure loading and material deformation are preliminarily discussed.
Cavitation in medicine
Authors: Brennen Christopher Earls
Published: August 2015

We generally think of bubbles as benign and harmless and yet they can manifest the most remarkable range of physical effects. Some of those effects are the stuff of our everyday experience as in the tinkling of a brook or the sounds of breaking waves at the beach. But even these mundane effects are examples of the ability of bubbles to gather, focus and radiate energy (acoustic energy in the above examples). In other contexts that focusing of energy can lead to serious technological problems as when cavitation bubbles eat great holes through ships' propeller blades or cause a threat to the integrity of the spillways at the Hoover Dam. In liquid-propelled rocket engines, bubbles pose a danger to the stability of the propulsion system, and in artificial heart valves they can cause serious damage to the red blood cells. In perhaps the most extraordinary example of energy focusing, collapsing cavitation bubbles can emit not only sound, but also light with black body radiation temperatures equal to that of the sun (Brennen 1995Cavitation and bubble dynamics). But, harnessed carefully, this almost unique ability to focus energy can also be put to remarkably constructive use. Cavitation bubbles are now used in a remarkable range of surgical and medical procedures, for example to emulsify tissue (most commonly in cataract surgery or in lithotripsy procedures for the reduction of kidney and gall stones) or to manipulate the DNA in individual cells. By creating cavitation bubbles non-invasively thereby depositing and focusing energy non-intrusively, one can generate minute incisions or target cancer cells. This paper will begin by briefly reviewing the history of cavitation phenomena and will end with a vision of the new horizons for the amazing cavitation bubble.
The singing vortex
Authors: Arndt R. , Pennings P. , Bosschers J. , van Terwisga T.
Published: August 2015

Marine propellers display several forms of cavitation. Of these, propeller-tip vortex cavitation is one of the important factors in propeller design. The dynamic behaviour of the tip vortex is responsible for hull vibration and noise. Thus, cavitation in the vortices trailing from tips of propeller blades has been studied extensively. Under certain circumstances cavitating vortices have been observed to have wave-like disturbances on the surfaces of vapour cores. Intense sound at discrete frequencies can result from a coupling between tip vortex disturbances and oscillating sheet cavitation on the surfaces of the propeller blades. This research article focuses on the dynamics of vortex cavitation and more in particular on the energy and frequency content of the radiated pressures.
Mapping high-growth phenotypes in the flux space of microbial metabolism
Authors: Güell Oriol , Massucci Francesco Alessandro , Font-Clos Francesc , Sagués Francesc , Serrano M. Ángeles
Published: August 2015

Experimental and empirical observations on cell metabolism cannot be understood as a whole without their integration into a consistent systematic framework. However, the characterization of metabolic flux phenotypes is typically reduced to the study of a single optimal state, such as maximum biomass yield that is by far the most common assumption. Here, we confront optimal growth solutions to the whole set of feasible flux phenotypes (FFPs), which provides a benchmark to assess the likelihood of optimal and high-growth states and their agreement with experimental results. In addition, FFP maps are able to uncover metabolic behaviours, such as aerobic fermentation accompanying exponential growth on sugars at nutrient excess conditions, that are unreachable using standard models based on optimality principles. The information content of the full FFP space provides us with a map to explore and evaluate metabolic behaviour and capabilities, and so it opens new avenues for biotechnological and biomedical applications.
The control of sea lice in Atlantic salmon by selective breeding
Authors: Gharbi Karim , Matthews Louise , Bron James , Roberts Ron , Tinch Alan , Stear Michael
Published: August 2015

Sea lice threaten the welfare of farmed Atlantic salmon and the sustainability of fish farming across the world. Chemical treatments are the major method of control but drug resistance means that alternatives are urgently needed. Selective breeding can be a cheap and effective alternative. Here, we combine experimental trials and diagnostics to provide a practical protocol for quantifying resistance to sea lice. We then combined quantitative genetics with epidemiological modelling to make the first prediction of the response to selection, quantified in terms of reduced need for chemical treatments. We infected over 1400 young fish with
Lepeophtheirus salmonis
, the most important species in the Northern Hemisphere. Mechanisms of resistance were expressed early in infection. Consequently, the number of lice per fish and the ranking of families were very similar at 7 and 17 days post infection, providing a stable window for assessing susceptibility to infection. The heritability of lice numbers within this time window was moderately high at 0.3, confirming that selective breeding is viable. We combined an epidemiological model of sea lice infection and control on a salmon farm with genetic variation in susceptibility among individuals. We simulated 10 generations of selective breeding and examined the frequency of treatments needed to control infection. Our model predicted that substantially fewer chemical treatments are needed to control lice outbreaks in selected populations and chemical treatment could be unnecessary after 10 generations of selection. Selective breeding for sea lice resistance should reduce the impact of sea lice on fish health and thus substantially improve the sustainability of Atlantic salmon production.
Predicting cortical bone adaptation to axial loading in the mouse tibia
Authors: Pereira A. F. , Javaheri B. , Pitsillides A. A. , Shefelbine S. J.
Published: August 2015

The development of predictive mathematical models can contribute to a deeper understanding of the specific stages of bone mechanobiology and the process by which bone adapts to mechanical forces. The objective of this work was to predict, with spatial accuracy, cortical bone adaptation to mechanical load, in order to better understand the mechanical cues that might be driving adaptation. The axial tibial loading model was used to trigger cortical bone adaptation in C57BL/6 mice and provide relevant biological and biomechanical information. A method for mapping cortical thickness in the mouse tibia diaphysis was developed, allowing for a thorough spatial description of where bone adaptation occurs. Poroelastic finite-element (FE) models were used to determine the structural response of the tibia upon axial loading and interstitial fluid velocity as the mechanical stimulus. FE models were coupled with mechanobiological governing equations, which accounted for non-static loads and assumed that bone responds instantly to local mechanical cues in an on–off manner. The presented formulation was able to simulate the areas of adaptation and accurately reproduce the distributions of cortical thickening observed in the experimental data with a statistically significant positive correlation (Kendall'sτrank coefficientτ= 0.51,p< 0.001). This work demonstrates that computational models can spatially predict cortical bone mechanoadaptation to a time variant stimulus. Such models could be used in the design of more efficient loading protocols and drug therapies that target the relevant physiological mechanisms.
Detecting somatic mutations in genomic sequences by means of Kolmogorov–Arnold analysis
Authors: Gurzadyan V. G. , Yan H. , Vlahovic G. , Kashin A. , Killela P. , Reitman Z. , Sargsyan S. , Yegorian G. , Milledge G. , Vlahovic B.
Published: August 2015

The Kolmogorov–Arnold stochasticity parameter technique is applied for the first time to the study of cancer genome sequencing, to reveal mutations. Using data generated by next-generation sequencing technologies, we have analysed the exome sequences of brain tumour patients with matched tumour and normal blood. We show that mutations contained in sequencing data can be revealed using this technique, thus providing a new methodology for determining subsequences of given length containing mutations, i.e. its value differs from those of subsequences without mutations. A potential application for this technique involves simplifying the procedure of finding segments with mutations, speeding up genomic research and accelerating its implementation in clinical diagnostics. Moreover, the prediction of a mutation associated with a family of frequent mutations in numerous types of cancers based purely on the value of the Kolmogorov function indicates that this applied marker may recognize genomic sequences that are in extremely low abundance and can be used in revealing new types of mutations.
Efficient conformational space exploration inab initioprotein folding simulation
Authors: Ullah Ahammed , Ahmed Nasif , Pappu Subrata Dey , Shatabda Swakkhar , Ullah A. Z. M. Dayem , Rahman M. Sohel
Published: August 2015

Ab initioprotein folding simulation largely depends on knowledge-based energy functions that are derived from known protein structures using statistical methods. These knowledge-based energy functions provide us with a good approximation of real protein energetics. However, these energy functions are not very informative for search algorithms and fail to distinguish the types of amino acid interactions that contribute largely to the energy function from those that do not. As a result, search algorithms frequently get trapped into the local minima. On the other hand, the hydrophobic–polar (HP) model considers hydrophobic interactions only. The simplified nature of HP energy function makes it limited only to a low-resolution model. In this paper, we present a strategy to derive a non-uniform scaled version of the real 20×20 pairwise energy function. The non-uniform scaling helps tackle the difficulty faced by a real energy function, whereas the integration of 20×20 pairwise information overcomes the limitations faced by the HP energy function. Here, we have applied a derived energy function with a genetic algorithm on discrete lattices. On a standard set of benchmark protein sequences, our approach significantly outperforms the state-of-the-art methods for similar models. Our approach has been able to explore regions of the conformational space which all the previous methods have failed to explore. Effectiveness of the derived energy function is presented by showing qualitative differences and similarities of the sampled structures to the native structures. Number of objective function evaluation in a single run of the algorithm is used as a comparison metric to demonstrate efficiency.
The nonlinear Schrödinger equation with
t
-periodic data: I. Exact results
Authors: Lenells J. , Fokas A. S.
Published: August 2015

We consider the nonlinear Schrödinger equation on the half-line with a given Dirichlet (Neumann) boundary datum which for large
t
tends to the periodic function

g
0

b

(
t
)

(

g
1

b

(
t
)

). Assuming that the unknown Neumann (Dirichlet) boundary value tends for large
t
to a periodic function

g
1

b

(
t
)

(

g
0

b

(
t
)

), we derive an easily verifiable condition that the functions

g
1

b

(
t
)

and

g
0

b

(
t
)

must satisfy. Furthermore, we propose two different methods, one based on the formulation of a Riemann–Hilbert problem and the other based on a perturbative approach, for constructing

g
1

b

(
t
)

(

g
0

b

(
t
)

) in terms of

g
0

b

(
t
)

(

g
1

b

(
t
)

).
Boundary integral formulation for interfacial cracks in thermodiffusive bimaterials
Authors: Morini L. , Piccolroaz A.
Published: August 2015

An original boundary integral formulation is proposed for the problem of a semi-infinite crack at the interface between two dissimilar elastic materials in the presence of heat flows and mass diffusion. Symmetric and skew-symmetric weight function matrices are used together with a generalized Betti's reciprocity theorem in order to derive a system of integral equations that relate the applied loading, the temperature and mass concentration fields, the heat and mass fluxes on the fracture surfaces and the resulting crack opening. The obtained integral identities can have many relevant applications, such as for the modelling of crack and damage processes at the interface between different components in electrochemical energy devices characterized by multi-layered structures (solid oxide fuel cells and lithium ions batteries).