bluuebunny/crossref_metadata_2025 huggingface dataset:
(P2-67) Torsade De Pointes and Ventricular Fibrillation Accompanying Intracerebral Hemorrhage
Authors: Hsu C. , Chen Y.
Published: May 2011

A 43-year-old patient with well healthy in the past was admitted after a accidental falling down injury. Upon arrival at the Emergent Department, he was unresponsive. (Glasgow coma scale = E1V1M1). The continuous Electrocardiological monitor demonstrated ventricular fibrillation without pulse, and the defibrillation (360 J) with intravenous Epinephrine (1 mg) push was given. The electrocardiogram (ECG) returned to sinus tachycardia. The endotracheal tube was intubated to keep airway patent and ventilation under the unstable vital sign. Ten minutes later, the polymorphic ventricular tachycardia (torsade de pointes) were recorded by continuous ECG. After defibrillation (360 J) twice with intravenous Epinephrine (1 mg) and Amiodarone (150 mg), the rhythm returned to normal sinus rhythm, and the vital sign recovered gradually. The laboratory evaluation showed no abnormality. The cranial computed tomography was done thereafter which showed occipital bone fracture with subarachnoid hemorrhage, subdural hemorrhage and epidural hemorrhage (Figure 2, arrows indicated hemorrhage). Clinical study has shown increased sympathetic activity in patients with acute intracranial hemorrhage. The increased level of catecholamines would lead to QT prolongation or hypokalemia, which are the predisposing factors of the development of torsade de pointes. Although, the definitive confirmation of a cause and effect relationship about intracranial hemorrhage and torsade de pointes is still controversial, the life-threatening arrhythmia, including atrioventricular blocks, ventricular tachycardia, and fibrillation, which accompany acute cerebral accidents in patients without cardiac disease is observed in many case reports. In our experience and clinical observation, patients should be constantly monitored after acute cerebral events. Besides, the treating team should be familiar with and well-trained in the diagnosis and treatment of cardiac arrhythmias.
(P2-73) Ocular Nerve Sheath Diameter for Evaluation of Raised Intracranial Pressure in Patients Presenting to the Emergency Department - A Prospective, Observational Study
Authors: Sinha T.P. , Bhoi S. , Rodha M. , Bhasin A. , Kumar S.
Published: May 2011

Background

Ultrasonography of optic nerve sheath diameter (ONSD) may be useful in detecting raised intracranial pressure (ICP) in head injury (HI). There is limited data from India.

Objective

The objective of this study was to evaluate the utility of measuring ONSD for diagnosis of raised intracranial pressure in HI victims in the emergency department.

Methods

Fifty-two HI patients presenting between February to August 2009 were included, A CT head scan was performed and simultaneous ocular ultrasound was done by an emergency physician who had underwent goal-directed training in ophthalmic sonography by a linear probe of 10 MHz. An ONSD greater than > 5 mm for patients > 15 years of age, 4.5 mm for 1–15 years of age, and 4 mm for infants were considered abnormal. The two modalities of diagnosis were compared.

Results

The median age was 30 years (Range = 0.25–72 years). A total of 90.4% were male and 9.6% were female. A total of 71.2% had severe HI, 19.2% had moderate HI, and 9.6% had mild HI. A raised ICP based on CT findings was present in 42 (80.8%) patients. Mean optic nerve diameter in patients with raised ICP was 5.11 + 1.56 mm compared to 5.04 + 1.6 mm in patients with no features of raised ICP. Sensitivity and specificity of ONSD as a screening test for detection of raised intracranial pressure were 57.1% and 40%, respectively with a positive predictive value and negative predictive value of 80% and 18.1%, respectively.

Conclusions

The evaluation of the ONSD diameter is a simple and non-invasive potential tool in initial assessment of raised intracranial pressure.
(P2-83) The Use of Focused Assessment with Sonography for Trauma in Patients with Blunt Abdominal Trauma or Pelvic Fracture in the Emergency Departments
Authors: Ufnal B. , Kamiński M. , Szostak M. , Trzos A. , Andres J.
Published: May 2011

Background

The role of FAST in diagnostic protocols has been adopted in most major trauma centers in well-developed countries. This procedure has become the initial diagnostic way in blunt abdominal trauma patients. However there are researches which show FAST is not reliable triage tool in patients with pelvic fracture.

Objectives

To evaluate the usefulness of Focused Assessment with Sonography for Trauma in diagnostic of blunt abdominal trauma patients and to bring attention to patients with pelvic fracture who should receive additional tests for the presence of peritoneal fluid.

Methods

An analysis of high-quality evidence resources was performed, limited to the articles published since 2005 year.

Results

99 articles were found during the search, of which 23 were accurate. 16 articles were based on original research.

Conclusion

Focused Assessment with Sonography for Trauma plays a key role in the investigation of blunt abdominal trauma and should be used in all emergency departments. FAST-negative patients can remain under observation except major pelvic injury patients. The evaluation of peritoneal fluid in this group has low sensitivity.
(P2-87) Policy Study of the Helmet Legislation in Kerala, India and its Implications
Authors: Vishwanath N.S.
Published: May 2011

Background

When implemented properly, universal helmet law increases helmet use substantially, bringing along a reduction in mortality and morbidity due to head injuries. Kerala has seen tremendous success in regards to various indicators for health within India. But when it comes to wearing helmets, the state lags behind others with reported rates as less as 27%.

Method

A cross-sectional survey of 300 two-wheel drivers in Thiruvananthapuram City was preformed, which looked into helmet wearing patterns, their determinants, and the risk perception among the respondents. Further, a content analysis of newspaper reports pertaining to helmet legislation from the Thiruvananthapuram edition of two leading newspapers was performed. The reports included were from the periods of July 2003 to June 2005 and July 2008 to June 2010. Lastly, in-depth interviews were conducted with informants from among the key stakeholders in helmet policy of the state.

Results

The study found 36.8% of the respondents wear a helmet. A scale to measure risk perception was developed for the purpose of this study. The four-item scale has been found to have internal consistency with a Cronbach alpha value of 0.74. The risk perception measured by using this scale has significant relation with helmet-wearing behavior. The content analysis helped in deriving a historical perspective of the policy along with the themes of reporting. The informant interviews provided expert opinions, problem identification, and specific recommendations.

Discussion

The practice of wearing a helmet is low, and people with lower risk perception have greater tendency not to wear helmets. Other findings also show that there are gaps in policy and lack of visionary leadership as far as the policy toward helmet legislation and its implementation.
(P2-88) To Assess the Effect of Camera Surveillance in Improving Compliance with Handwashing Practices in the ICU Setting
Authors: Agarwal D. , Chauhan S.
Published: May 2011

Background

Handwashing has been shown to be the most effective means of reducing cross infection in the healthcare environment. However, staff compliance remains low in the real setting.

Methods

A prospective study was carried out over one month period in one cubicle of neurosurgery intensive care unit (ICU). A surveillance camera which was previously installed and functioning was focused on a cubicle of three patients, and recordings of the previous 24 hours were reviewed every day for 15 days. The number of incidents in which handwashing was required but not performed was recorded. An incident was defined as any one of the following: (1) handwashing not performed by healthcare workers; (2) touching different patients without handwashing; (3) using the same gloves for different patients and for different procedures; (4) not performing handwashing after finishing the procedures. Following this 15-day period, all staff were verbally instructed during every shift that they were under surveillance for the next 15 days. Camera recordings of the previous 24 hours were similarly reviewed every day for these 15 days and incidents recorded.

Results

In the first 15-days period, there was a total of 480 incidents when handwashing was not performed. Of the incidents, 83%(n = 401) occurred during the night shift, especially during the early morning hours. In the subsequent 15 days when the staff were informed that they were under camera surveillance, the total number of events when handwashing was not done was 140. The difference between the two periods was statistically significant(p < 0.01 > .

Conclusion

Handwashing is practiced poorly in this ICU. As the maximum number of incidents occurred during the night shift, poor motivation may be one of the factors for this behavior. This study shows that camera surveillance plays a major role in changing the staff behavior and may improve compliance for handwashing.
(P2-89) Investigation, the Association of Cardiac Risk Factors and the Risk of Acute Myocardial Infarction, in ED Patients with Non-Diagnostic ECG
Authors: Kashani P.
Published: May 2011

Objective

To investigate the association of cardiac Risk factors and the risk of Acute myocardial infarction, in ED patients with non-diagnostic ECG. Methods:

Results

474 patients were enrolled,150 had non diagnostic ECG In this study HTN with p-value = 0/012 (> 0/05), HIP with p-value = 0/0001 (> 0/001), FH with p-value = 0/001(> 0/01) was significantly more prevalent in those who ruled in for AMI.

Conclusion

In the past studies in patients with non-diagnostic ECG only hypertension Was significantly more prevalent in those who ruled in for AMI and cardiac risk factors have limited clinical value in diagnosing of AMI in ED patients. In this study HLP, HTN, FH was significantly more prevalent in those who ruled in for AMI An observational study is conducted in an educational hospital in Shahid Beheshti university during a period of two years. In this study, patients with symptoms suggestive of AMI including. chest pain, Dyspnea, palpitation, syncope, cerebrovascular accident, nausea, vomiting, vertigo, loss of consciousness were enrolled. Demographic, historical feature and risk factors, such as age, sex, diabetes, hypertension, hyper lipidemia, renal failure, positive family history of CAD, smoking, substance abuse, Alcohol use in the past 24 hours, cocaine use in the past 48 h were recorded. Nondiagnost ECG including these categories: Normal, non specific, early Repolarization, abnormal without signs of ischemia such as old bundle branch block, LVH, … A final diagnosis of Acute myocardial infarction was determined by CK - MB and Troponin - 1.
(P2-90) Modified Delphi Study to Determine Optimal Data Elements for Inclusion in an Emergency Management Database System
Authors: Jabar A. , Rüter A. , Wallis L.A.
Published: May 2011

Topic

Information and communication technology (ICT).

Objectives

ICT are introduced into organizations with the goals of managing resources, increasing efficiency and work productivity and reducing workload. In the context of developing countries, these goals are accentuated given the existing conditions. The aim of this study was to identify hospital institutional capacity indicators to provide recommendations to an emergency management database system operating in the Western Cape province of South Africa as http://hospitalbedbureau.co.za/.

Methodology

A two round modified Expert Delphi study was conducted by email. A panel of 16 experts drawn from the fields of emergency medicine, critical care, trauma surgery and disaster medicine were consulted. Participants were initially asked to propose hospital institutional capacity indicators that warranted inclusion in the emergency management database system currently operating in Cape Town, South Africa. In the second round these proposals were collated and scored using a 7 point Likert scale. Areas that did not reach consensus in the Delphi study will be presented as synopsis statements for discussion at the Emergency Medicine Symposium hosted by the department of Accident and Emergency Western Cape.

Results

Round 1 comprised 237 statements. Consensus was defined a priori to be > 80%. A total of 52 of 237 statements had reached consensus upon completion of the Delphi study. This represented 21.9% of the total number of statements. Of these 20 reached consensus at > 90% and 32 reached consensus at > 80%.

Conclusion

The use of a Delphi study achieved consensus in aspects of hospital institutional capacity that can be translated into practical recommendations for implementation by the local emergency management database system. Additionally, areas of non-consensus have been identified where further work is required.
(P2-92) Hueh Emergency Medicine Triage: Lessons in Crowd Control
Authors: Kaufmann K.R. , Oh E. , Lin J.
Published: May 2011

Background

On 12 January 2010 Port-au-Prince, Haiti was struck by a 7.0 Mw earthquake that devastated the city and destroyed much of the Haiti University and Educational Hospital. In the following weeks, a tent hospital was erected at the site and hundreds of patients were seen daily by expatriate healthcare volunteers. The high volumes of patients, disorganized hospital grounds, and high levels of stress among patients led to issues of crowd control.

Discussion

To improve security a new triage system was designed and implemented based on current emergency medicine models. This design addressed patient flow, triage, environmental conditions, and differentiation of emergency services. The results of this system were a streamlined triage system as well as improved safety.

Conclusions

During the chaos following the Haiti earthquake, a triage design was implemented at the HUEH that lead to improved Emergency Department patient flow and hospital safety.
(P2-97) The Differences Between Triage and Start that are Applied to Train Derailment
Authors: Hashimoto A. , Ueda T. , Hirata J. , Kuboyama K. , Yamada T. , Kotani J.
Published: May 2011

The derailment accident occurred on 25 April 2005. 562 passengers were injured and 107 people died. Based on our periodic training in mass disaster triage, we accepted 113 wounded victims regardless of the severity of their condition. Initially, Simple Triage and Rapid Treatment was supposed to be performed by an emergency physician as a triage officer but START is not the most effective method for this case because patients of different severity levels were admitted to our hospital. Therefore, we performed triage by inspection and palpation based on our experience and intuition. Patient's facial color, breathing patterns, and trauma were processed for inspection. Furthermore, palpation was carried on without counting pulse and we diagnosed victims based upon strength of pulse and sensation of cold. From inspirational and sensuous diagnosis, the severity was determined. Comparing START with experiential and intuitive triage, differences between level of consciousness, the severity of trauma, and vital sign were examined. In addition, which components were necessary for primary survey was also reviewed.

Method

Severe or moderate, which were evaluated from ISS, vital sign, and Revised Trauma Score: RTS, Probability of survival: PS, were classified and then agreement rate, sensitivity, and specificity between START (S model) and triage (D model) were assessed. For START, data was extracted from clinical records.

Result

Agreement rate between the S model and the D model was 76.9%. Moreover, at the percentage of questions answered, the S model showed 84.2% and the D model showed 68.4%. Thus the experiment showed significant difference. 5 over triage cases appeared when the D model was operated. RTS, vital sign, and PS did not show great differences.

Conclusion

It could be difficult and insufficient to use START when a mass disaster occurs, however experiential and intuitive triage is also effective as START.
(P2-102) Haiti Earthquake: Ankara UMKE First Term Field Studies
Authors: Ince E. , DemİrkasimoĞlu M. , GÜleÇ M.A. , ÖzoĞlu C. , ÇoŞkun A.
Published: May 2011

In this study the cases occurred due to a direct effect of trauma and trauma-induced complications that might needed medical care and intervention in the field after the first 5 days of disaster were investigated. The cases in the field were determined by field screening and individual medical and surgical interventions have been conducted. The wounded that cannot be treated in the field were taken to the field hospital by the only available emergency ambulance, owned by Turkish Health Teams, to be treated by specialists. In the conclusion of the paper, the necessity and effectiveness of interventions provided to sick/wounded persons in the field who couldn't reach hospital was discussed.
Use of EcoTILLING to identify natural allelic variants of rice candidate genes involved in salinity tolerance
Authors: Negrão S. , Almadanim C. , Pires I. , McNally K. L. , Oliveira M. M.
Published: May 2011

Rice is a salt-sensitive species with enormous genetic variation for salt tolerance hidden in its germplasm pool. The EcoTILLING technique allows us to assign haplotypes, thus reducing the number of accessions to be sequenced, becoming a cost-effective, time-saving and high-throughput method, ideal to be used in laboratories with limited financial resources. Aiming to find alleles associated with salinity tolerance, we are currently using the EcoTILLING technique to detect single nucleotide polymorphisms (SNPs) and small indels across 375 germplasm accessions representing the diversity available in domesticated rice. We are targeting several genes known to be involved in salt stress signal transduction (OsCPK17) or tolerance mechanisms (SalT). So far, we found a total of 15 and 23 representative SNPs or indels in OsCPK17 and SalT, respectively. These natural allelic variants are mostly located in 3′-untranslated region, thus opening a new path for studying their potential contribution to the regulation of gene expression and possible role in salt tolerance.
Estimation of catchment averaged sensible heat fluxes using a large aperture scintillometer
Authors: Samain Bruno , Ferket Bram V. A. , Defloor Willem , Pauwels Valentijn R. N.
Published: May 2011

Evapotranspiration rates at the catchment scale are very difficult to quantify. One possible manner to continuously observe this variable could be the estimation of sensible heat fluxes (H) across large distances (in the order of kilometers) using a large aperture scintillometer (LAS), and inverting these observations into evapotranspiration rates, under the assumption that the LAS observations are representative for the entire catchment. The objective of this paper is to assess whether measured sensible heat fluxes from a LAS over a long distance (9.5 km) can be assumed to be valid for a 102.3 km2 heterogeneous catchment. Therefore, a fully process‐based water and energy balance model with a spatial resolution of 50 m has been thoroughly calibrated and validated for the Bellebeek catchment in Belgium. A footprint analysis has been performed. In general, the sensible heat fluxes from the LAS compared well with the modeled sensible heat fluxes within the footprint. Moreover, as the modeled H within the footprint has been found to be almost equal to the modeled catchment averaged H, it can be concluded that the scintillometer measurements over a distance of 9.5 km and an effective height of 68 m are representative for the entire catchment.
Effect of spatial heterogeneity of runoff generation mechanisms on the scaling behavior of event runoff responses in a natural river basin
Authors: Li Hongyi , Sivapalan Murugesu
Published: May 2011

This paper presents a theoretical investigation of the effects of spatial heterogeneity of runoff generation on the scaling behavior of runoff timing responses. A previous modeling study on the Illinois River Basin in Oklahoma had revealed a systematic spatial trend in the relative dominance of different runoff generation mechanisms, attributable to corresponding systematic trends in landscape properties. Considering the differences in the timing of hillslope responses between the different runoff mechanisms, this paper explores their impacts on the catchment‐scale runoff routing responses, including how they change with spatial scale. For this purpose we utilize a distributed, physically based hydrological model, with a fully hydraulic stream network routing component. The model is used to generate instantaneous response functions (IRF) for nested catchments of a range of sizes along the river network and quantitative measures of their shape, e.g., peak and time to peak. In order to separate the effects of soil heterogeneity from those due to basin geomorphology, the model simulations are carried out for three hypothetical cases that make assumptions regarding landscape properties (uniform, a systematic trend, and heterogeneity plus the trend), repeating these simulations under wet and dry antecedent conditions. The simulations produced expected and also surprising results. The power law relationship between the peak of the IRF and drainage area is shown to be flatter under wet conditions than under dry conditions, even though the (faster) saturation excess mechanism is more dominant under wet conditions. This result appears to be caused by partial area runoff generation: under wet conditions, the fraction of saturation area is about 30%, while under dry conditions it is less than 10% for the same input of rainfall. This means travel times associated with overland flow (which mostly contributes to the peak and time to peak) are, in fact, longer during wet conditions than during dry conditions. The power law relationship between peak and drainage area also exhibits a scaling break at around 1000 km2, which can be shown to be related to the peculiar geomorphology of the catchment.
Issues of spatial correlation arising from the use of TRMM rainfall estimates in the Brazilian Amazon
Authors: Clarke Robin T. , Buarque Diogo Costa , de Paiva Rodrigo Cauduro Dias , Collischonn Walter
Published: May 2011

This paper discusses issues arising when Tropical Rainfall Measuring Mission (TRMM) estimates of rainfall characteristics are calculated for the sparsely gauged Brazilian Amazon. The particular issue considered is the calculation of statistical uncertainty in (1) comparisons between TRMM estimates of rainfall characteristics and their corresponding rain gauge estimates and (2) interpolated estimates of rainfall characteristics, which are conditional on local TRMM estimates near ungauged sites. Three characteristics selected for particular comparison are (1) mean annual rainfall, 1998–2005, (2) mean value, over these years, of the 95% quantile of within‐year daily rainfall, and (3) mean number of days in the year with rainfall of 2 mm or more. The paper demonstrates how positive spatial correlation leads to underestimation of the uncertainty in the comparisons (i.e., the standard errors of differences), so that the significance of differences, when observed, is likely to be overestimated if spatial correlation is ignored. For the three characteristics mentioned, the Matérn spatial correlation function with shape parameter κ = 1/2, giving an exponential correlation function, was found to be adequate for modeling spatial correlation. It is also argued that the statistic 1 − b, where b is the slope of the regression of a rain gauge estimate of a rainfall characteristic on its counterpart derived from satellite instrumentation, is a measure of the errors in the satellite (spatially averaged) estimates. Finally, although issues of spatial correlation are discussed with particular reference to rainfall, it is argued that the same issues arise whenever satellite‐derived estimates of a component of the water cycle must be combined with ground‐based measurements.
Isolated Human and Rat Cerebral Arteries Constrict to Increases in Flow: Role of 20-HETE and TP Receptors
Authors: Toth Peter , Rozsa Bernadett , Springo Zsolt , Doczi Tamas , Koller Akos
Published: May 2011

Elevation of intraluminal pressure increases vasomotor tone, which thought to have a substantial role in regulation of cerebral blood flow (CBF). Interestingly, responses of cerebral vessels to increases in flow varied and have not been studied in human cerebral arteries. We hypothesized that increases in flow elicit constrictions of isolated human and rat cerebral arteries and aimed to elucidate the underlying mechanisms. Human cerebral arteries and rat middle cerebral arteries constricted to increases in flow ( P<0.05). Simultaneous increase in intraluminal flow + pressure further reduced the diameter compared with pressure-induced changes ( P<0.05), leading to constant estimated CBF. Flow-induced constrictions were abolished by HET0016 (inhibitor of synthesis of 20-hydroxyeicosatetraenoic acid (20-HETE) or inhibition of COXs or blocking TP (thromboxane A2/prostaglandin H2, receptors and attenuated by scavenging reactive oxygen species (ROS). Flow-enhanced ROS formation was significantly reduced by HET0016. In conclusion, in human and rat cerebral arteries (1) increases in flow elicit constrictions, (2) signaling mechanism of flow-induced constriction of cerebral arteries involves enhanced production of ROS, COX activity, and mediated by 20-HETE via TP receptors, and (3) we propose that simultaneous operation of pressure- and flow-induced constrictions is necessary to provide an effective autoregulation of CBF.
Porous hot-wire deposited WO3 films with high optical transmission
Authors: Papadimitropoulos G. , Vourdas N. , Giannakopoulos K. , Vasilopoulou M. , Davazoglou D.
Published: May 2011

Tungsten oxide films were deposited on Si and fused silica substrates by heating metallic filaments at temperatures of 650, 750, and 800 °C at a pressure of 1 Torr of N2. During deposition the substrates remained at or near room temperature. These hot-wire (hwWO3) films were found to be composed by amorphous material and highly transparent within the range 350−1000 nm. Spectroscopic ellipsometry measurements have shown that the real part of refractive index (n) of hwWO3 films exhibited features similar to those of stoichiometric WO3 films indicating that hwWO3 films were also stoichiometric. The values of n were found to depend on deposition time (film thickness) and after 2 s, have fallen below 1.45 within the visible range, while the imaginary part (k) remained near zero. These low values of n and k were attributed to the porosity of hwWO3 films, which as shown by simulations based on the effective medium approximation, after 2 s of deposition saturated near 60%. As shown by scanning electron microscopy measurements, hwWO3 films were composed by grains with dimensions of the order of 15−20 nm increasing with thickness, and voids between these grains. Transmission electron microscopy (TEM) measurements have shown that these grains were composed by others with dimensions near 5 nm and voids between them. The above microscopy measurements explain the high porosity of hwWO3 films. Moreover, they indicate that hwWO3 films were grown by stoichiometric WO3 particles with dimensions of the order of 5 nm or clusters of such species, which evaporated from the filament and then condensed on the cold substrate.
A compact electron cyclotron resonance proton source for the Paul Scherrer Institute's proton accelerator facility
Authors: Baumgarten C. , Barchetti A. , Einenkel H. , Goetz D. , Schmelzbach P. A.
Published: May 2011

A compact electron cyclotron resonance proton source has been developed and installed recently at the Paul Scherrer Institute's high intensity proton accelerator. Operation at the ion source test stand and the accelerator demonstrates a high reliability and stability of the new source. When operated at a 10 − 12 mA net proton current the lifetime of the source exceeds 2000 h. The essential development steps towards the observed performance are described.
Simulation of near-field optical manipulator using the combination of a near-field scanning optical microscope probe and an atomic force microscope metallic probe
Authors: Liu Binghui , Yang Lijun , Wang Yang
Published: May 2011

We propose a physical model to calculate the trapping force on a nanoparticle trapped by the system using the combination of a near-field scanning optical microscope (NSOM) probe and an atomic force microscope (AFM) metallic probe. Such a near-field trap is produced by evanescent illumination from the NSOM probe and light scattering at the tip of the AFM metallic probe. By using the Maxwell stress tensor through the electric field distribution obtained with the three-dimensional finite difference time domain (3-D FDTD) method, the dependence of the trapping force on the system parameters is discussed, and trapping properties including near-field distribution, trapping position, and the role of other forces versus trapping force are revealed. The results indicate that a particle down to tens of nanometers in size can be trapped toward the tip of an AFM probe with a lower laser intensity (∼1040 W/mm2) than that required by conventional optical manipulators (∼105 W/mm2).
Thermosolutal convection at infinite prandtl number with or without rotation: Bifurcation and stability in physical space
Authors: Park Jungho
Published: May 2011

We examine the nature of the thermosolutal convection with or without rotation in the infinite Prandtl number regime, which is applicable to magma chambers. The onset of bifurcation and the structure of the bifurcated solutions in this double diffusion problem are analyzed. The stress-free boundary condition is imposed at the top and bottom plates confining the fluid. For the rotation free case, two-dimensional Boussinesq equations are considered and we prove that there are bifurcating solutions from the basic solution and that the bifurcated solutions consist of only one cycle of steady state solutions that are homeomorphic to S1. By thoroughly investigating the structure and transitions of the solutions of the thermosolutal convection problem in physical space, we confirm that the bifurcated solutions are indeed structurally stable. In the presence of rotation, we consider three-dimensional Boussinesq equations and we can get similar results as of the rotation free case. We also see how intensively the rotation inhibits the onset of convective motion. In turn, this will corroborate and justify the suggested results with the physical findings about the presence of roll structure.
Transport properties of free carriers in semiconductors studied by terahertz time-domain magneto-optical ellipsometry
Authors: Yatsugi Kenichi , Matsumoto Naoki , Nagashima Takeshi , Hangyo Masanori
Published: May 2011

We have developed a terahertz time-domain magneto-optical ellipsometry to deduce the effective mass, scattering time, density, and type (n or p) of free carriers independently. The parameters are derived from diagonal and off-diagonal components of the complex dielectric tensor obtained by measurements of magneto-optical Kerr effects under a magnetic field of 0.46 T using the generalized Drude model. The derivation of these parameters for n-type InAs wafers with different carrier densities is demonstrated. The carrier density dependence of the effective mass agrees well with previously reported experimental results and theoretical calculations that take into account nonparabolicity of conduction bands.
Radiative thermal escape in intermediate band solar cells
Authors: Luque A. , Martí A. , Antolín E. , Linares P. G. , Tobías I. , Ramiro I.
Published: May 2011

To achieve high efficiency, the intermediate band (IB) solar cell must generate photocurrent from sub-bandgap photons at a voltage higher than that of a single contributing sub-bandgap photon. To achieve the latter, it is necessary that the IB levels be properly isolated from the valence and conduction bands. We prove that this is not the case for IB cells formed with the confined levels of InAs quantum dots (QDs) in GaAs grown so far due to the strong density of internal thermal photons at the transition energies involved. To counteract this, the QD must be smaller.
Ecological determinants of recruitment to populations of a temperate reef fish, Trachinops caudimaculatus (Plesiopidae)
Authors: Hunt Taylor L. , Ford John R. , Swearer Stephen E.
Published: May 2011

Although recruitment is often influenced by microhabitat characteristics that affect larval settlement and post-settlement growth and survival, the influence of some habitat features, such as the presence of conspecifics and the accessibility of food, are poorly understood, particularly on temperate reefs. We investigated the ecological determinants of recruitment in the southern hulafish (Trachinops caudimaculatus; McCoy, 1890), a small zooplanktivorous reef fish in Port Phillip Bay, Australia. We hypothesised that T. caudimaculatus would show positive relationships with microhabitat characteristics that provide greater access to food and shelter for newly settled recruits. To test this hypothesis, we surveyed T. caudimaculatus populations and associated microhabitat characteristics on shallow reefs. Overall, habitat characteristics explained 65% of the variation in recruitment, with recruitment greatest to reefs with abundant (1) adults, suggesting positive settlement cues and benefits to survival through shoaling, (2) accessible food (numerous prey), suggesting enhanced survival because of faster growth, and (3) shelter, suggesting enhanced survival through greater availability of refuges from predation. As T. caudimaculatus is an important prey species and sensitive to changes in pelagic productivity, mobile predators and water quality, we suggest it may be a suitable bioindicator of changes to temperate reef ecosystems.
Cross-linking, ligation, and sequencing of hybrids reveals RNA–RNA interactions in yeast
Authors: Kudla Grzegorz , Granneman Sander , Hahn Daniela , Beggs Jean D. , Tollervey David
Published: May 2011

Many protein–protein and protein–nucleic acid interactions have been experimentally characterized, whereas RNA–RNA interactions have generally only been predicted computationally. Here, we describe a high-throughput method to identify intramolecular and intermolecular RNA–RNA interactions experimentally by cross-linking, ligation, and sequencing of hybrids (CLASH). As validation, we identified 39 known target sites for box C/D modification-guide small nucleolar RNAs (snoRNAs) on the yeast pre-rRNA. Novel snoRNA-rRNA hybrids were recovered between snR4-5S and U14-25S. These are supported by native electrophoresis and consistent with previously unexplained data. The U3 snoRNA was found to be associated with sequences close to the 3′ side of the central pseudoknot in 18S rRNA, supporting a role in formation of this structure. Applying CLASH to the yeast U2 spliceosomal snRNA led to a revised predicted secondary structure, featuring alternative folding of the 3′ domain and long-range contacts between the 3′ and 5′ domains. CLASH should allow transcriptome-wide analyses of RNA–RNA interactions in many organisms.
Characterization of a canine homolog of hepatitis C virus
Authors: Kapoor Amit , Simmonds Peter , Gerold Gisa , Qaisar Natasha , Jain Komal , Henriquez Jose A. , Firth Cadhla , Hirschberg David L. , Rice Charles M. , Shields Shelly , Lipkin W. Ian
Published: May 2011

An estimated 3% of the world's population is chronically infected with hepatitis C virus (HCV). Although HCV was discovered more than 20 y ago, its origin remains obscure largely because no closely related animal virus homolog has been identified; furthermore, efforts to understand HCV pathogenesis have been hampered by the absence of animal models other than chimpanzees for human disease. Here we report the identification in domestic dogs of a nonprimate hepacivirus. Comparative phylogenetic analysis of the canine hepacivirus (CHV) confirmed it to be the most genetically similar animal virus homolog of HCV. Bayesian Markov chains Monte Carlo and associated time to most recent common ancestor analyses suggest a mean recent divergence time of CHV and HCV clades within the past 500–1,000 y, well after the domestication of canines. The discovery of CHV may provide new insights into the origin and evolution of HCV and a tractable model system with which to probe the pathogenesis, prevention, and treatment of diseases caused by hepacivirus infection.
Locally nilpotent derivations with a PID ring of constants
Authors: Barkatou Moulay A. , El Kahoui M’hammed
Published: May 2011

Let

K

\mathcal {K}

be a commutative field of characteristic zero,

A

\mathcal {A}

be a domain containing

K

\mathcal {K}

and

∂
\partial

be a locally nilpotent

K

\mathcal {K}

-derivation of

A

\mathcal {A}

. We give in this paper a description of the differential

K

\mathcal {K}

-algebra

(

A

,
∂
)

(\mathcal {A},\partial )

under the assumptions that the ring of constants

A

∂

\mathcal {A}^{\partial }

of

∂
\partial

is a PID,

∂
\partial

is fixed point free and its special fibers are reduced.
Caspase activity is not required for the mitotic checkpoint or mitotic slippage in human cells
Authors: Lee Kyunghee , Kenny Alison E. , Rieder Conly L.
Published: May 2011

Biochemical studies suggest that caspase activity is required for a functional mitotic checkpoint (MC) and mitotic slippage. To test this directly, we followed nontransformed human telomerase immortalized human retinal pigment epithelia (RPE-1) cells through mitosis after inhibiting or depleting selected caspases. We found that inhibiting caspases individually, in combination, or in toto did not affect the duration or fidelity of mitosis in otherwise untreated cells. When satisfaction of the MC was prevented with 500 nM nocodazole or 2.5 μM dimethylenastron (an Eg5 inhibitor), 92–100% of RPE-1 cells slipped from mitosis in the presence of pan-caspase inhibitors or after simultaneously depleting caspase-3 and -9, and they did so with the same kinetics (∼21–22 h) as after treatment with nocodazole or Eg5 inhibitors alone. Surprisingly, inhibiting or depleting caspase-9 alone doubled the number of nocodazole-treated, but not Eg5-inhibited, cells that died in mitosis. In addition, inhibiting or depleting caspase-9 and -3 together accelerated the rate of slippage ∼40% (to ∼13–15 h). Finally, nocodazole-treated cells that recently slipped through mitosis in the presence or absence of pan-caspase inhibitors contained numerous BubR1 foci in their nuclei. From these data, we conclude that caspase activity is not required for a functional MC or for mitotic slippage.
Evolutionary optimization of material properties of a tropical seed
Authors: Lucas Peter W. , Gaskins John T. , Lowrey Timothy K. , Harrison Mark E. , Morrogh-Bernard Helen C. , Cheyne Susan M. , Begley Matthew R.
Published: May 2011

Here, we show how the mechanical properties of a thick-shelled tropical seed are adapted to permit them to germinate while preventing their predation. The seed has evolved a complex heterogeneous microstructure resulting in hardness, stiffness and fracture toughness values that place the structure at the intersection of these competing selective constraints. Analyses of different damage mechanisms inflicted by beetles, squirrels and orangutans illustrate that cellular shapes and orientations ensure damage resistance to predation forces imposed across a broad range of length scales. This resistance is shown to be around the upper limit that allows cracking the shell via internal turgor pressure (i.e. germination). Thus, the seed appears to strike an exquisitely delicate adaptive balance between multiple selection pressures.
A numerical implementation of Fokas boundary integral approach: Laplace's equation on a polygonal domain
Authors: Fornberg Bengt , Flyer Natasha
Published: May 2011

A recently discovered transform approach allows a large class of PDEs to be solved in terms of boundary and/or contour integrals. We introduce here a spectrally accurate numerical discretization of this approach for the case of Laplace's equation on a polygonal domain, and compare it against an also spectrally accurate implementation of the traditional boundary integral formulation.
Extensive reproductive disruption, ovarian masculinization and aromatase suppression in Atlantic croaker in the northern Gulf of Mexico hypoxic zone
Authors: Thomas Peter , Rahman Md. Saydur
Published: May 2011

The long-term impacts on marine ecosystems of the recent dramatic worldwide increase in the incidence of coastal hypoxia are unknown. Here, we show widespread reproductive disruption in Atlantic croakers collected from hypoxic sites approximately 120 km apart in the extensive northern Gulf of Mexico continental shelf hypoxic zone. Gonadal growth and gamete production were impaired in croakers from hypoxic sites compared with fish from reference normoxic sites east of the Mississippi River Delta. Male germ cells were detected in approximately 19 per cent of croaker ovaries collected in the hypoxic region, but were absent in ovaries from normoxic sites. In addition, the sex ratio was skewed towards males at the hypoxic sites. The masculinization and other reproductive disruptions were associated with declines in neuroendocrine function, as well as ovarian and brain expression of aromatase (the enzyme that converts androgens to oestrogens). A similar incidence of ovarian masculinization and decline in ovarian aromatase expression were observed in croaker after chronic laboratory hypoxia exposure, indicating that ovarian masculinization is a specific hypoxia response and is due to decreased aromatase activity. The results suggest severe reproductive impairment can occur over large coastal regions in marine fish populations exposed to seasonal hypoxia, with potential long-term impacts on population abundance.
Anaemia, hypothyroidism and immune suppression associated with polychlorinated biphenyl exposure in bottlenose dolphins (
Tursiops truncatus
)
Authors: Schwacke Lori H. , Zolman Eric S. , Balmer Brian C. , De Guise Sylvain , George R. Clay , Hoguet Jennifer , Hohn Aleta A. , Kucklick John R. , Lamb Steve , Levin Milton , Litz Jenny A. , McFee Wayne E. , Place Ned J. , Townsend Forrest I. , Wells Randall S. , Rowles Teresa K.
Published: May 2011

Polychlorinated biphenyls (PCBs), persistent chemicals widely used for industrial purposes, have been banned in most parts of the world for decades. Owing to their bioaccumulative nature, PCBs are still found in high concentrations in marine mammals, particularly those that occupy upper trophic positions. While PCB-related health effects have been well-documented in some mammals, studies among dolphins and whales are limited. We conducted health evaluations of bottlenose dolphins (
Tursiops truncatus
) near a site on the Georgia, United States coast heavily contaminated by Aroclor 1268, an uncommon PCB mixture primarily comprised of octa- through deca-chlorobiphenyl congeners. A high proportion (26%) of sampled dolphins suffered anaemia, a finding previously reported from primate laboratory studies using high doses of a more common PCB mixture, Aroclor 1254. In addition, the dolphins showed reduced thyroid hormone levels and total thyroxine, free thyroxine and triiodothyronine negatively correlated with PCB concentration measured in blubber (
p
= 0.039, < 0.001, 0.009, respectively). Similarly, T-lymphocyte proliferation and indices of innate immunity decreased with blubber PCB concentration, suggesting an increased susceptibility to infectious disease. Other persistent contaminants such as DDT which could potentially confound results were similar in the Georgia dolphins when compared with previously sampled reference sites, and therefore probably did not contribute to the observed correlations. Our results clearly demonstrate that dolphins are vulnerable to PCB-related toxic effects, at least partially mediated through the endocrine system. The severity of the effects suggests that the PCB mixture to which the Georgia dolphins were exposed has substantial toxic potential and further studies are warranted to elucidate mechanisms and potential impacts on other top-level predators, including humans, who regularly consume fish from the same marine waters.
Spatial heterogeneity in the effects of climate and density-dependence on dispersal in a house sparrow metapopulation
Authors: Pärn Henrik , Ringsby Thor Harald , Jensen Henrik , Sæther Bernt-Erik
Published: May 2011

Dispersal plays a key role in the response of populations to climate change and habitat fragmentation. Here, we use data from a long-term metapopulation study of a non-migratory bird, the house sparrow (Passer domesticus), to examine the influence of increasing spring temperature and density-dependence on natal dispersal rates and how these relationships depend on spatial variation in habitat quality. The effects of spring temperature and population size on dispersal rate depended on the habitat quality. Dispersal rate increased with temperature and population size on poor-quality islands without farms, where house sparrows were more exposed to temporal fluctuations in weather conditions and food availability. By contrast, dispersal rate was independent of spring temperature and population size on high-quality islands with farms, where house sparrows had access to food and shelter all the year around. This illustrates large spatial heterogeneity within the metapopulation in how population density and environmental fluctuations affect the dispersal process.
Calcein labelling and electrophysiology: insights on coral tissue permeability and calcification
Authors: Tambutté Eric , Tambutté Sylvie , Segonds Natacha , Zoccola Didier , Venn Alexander , Erez Jonathan , Allemand Denis
Published: May 2011

The mechanisms behind the transfer of molecules from the surrounding sea water to the site of coral calcification are not well understood, but are critical for understanding how coral reefs are formed. We conducted experiments with the fluorescent dye calcein, which binds to calcium and is incorporated into growing calcium carbonate crystals, to determine the permeability properties of coral cells and tissues to this molecule, and to determine how it is incorporated into the coral skeleton. We also compared rates of calcein incorporation with rates of calcification measured by the alkalinity anomaly technique. Finally, by an electrophysiological approach, we investigated the electrical resistance of coral tissues in order to better understand the role of tissues in ionic permeability. Our results show that (i) calcein passes through coral tissues by a paracellular pathway, (ii) intercellular junctions control and restrict the diffusion of molecules, (iii) intercellular junctions should have pores of a size higher than 13 Å and lower than 20 nm, and (iv) the resistance of the tissues owing to paracellular junctions has a value of 477 ± 21 Ohm cm2. We discuss the implication of our results for the transport of calcium involved in the calcification process.