bluuebunny/crossref_metadata_2025 huggingface dataset:
MRI Diagnosis of Recurrent Pigmented Villonodular Synovitis following Total Joint Arthroplasty
Authors: Friedman Talia , Chen Timothy , Chang Anthony
Published: January 2013

Pigmented villonodular synovitis (PVNS) can recur after complete synovectomy and even after total joint replacement. In the authors’ experience, there is a misconception that MRI may not be useful to diagnose PVNS in the setting of a total joint replacement due to dephasing artifact from metal. While there are case reports of PVNS in patients with total joint replacement diagnosed surgically, to our knowledge, diagnosis of recurrent PVNS by MRI following total joint replacement has not been reported. This report illustrates the utility of MRI in the diagnosis of recurrent PVNS following total joint replacement by reviewing two cases of pathologically correlated PVNS recurrence following arthroplasty, and two cases in which PVNS recurrence is strongly suspected, though pathological correlation is not available.
Hip Resurfacing: A 40-Year Perspective
Authors: Amstutz Harlan C. , Le Duff Michel J.
Published: January 2013

Background

Saving bone by resurfacing the femoral head is not a new concept and the appeal for this type of hip replacement has remained despite the difficulties to find a bearing material suitable for this procedure.

Purpose

In this article, the unique experience of a surgeon who has been performing hip resurfacing since its early development is presented, along with a comparative analysis of the performance of successive designs.

Results

The overall 10-year Kaplan–Meier survivorship of the early designs with polyethylene bearings did not exceed 62% while that of the current Conserve®Plus metal-on-metal hybrid design implanted with second generation surgical technique is in excess of 92%. Further exceptional, in the 10-year survivorship, 99.7% has been achieved with femoral size of 46 mm and good bone quality. Cementless acetabular components provide better enduring fixation than cemented designs.

Discussion

Metal-on-metal is currently and fortunately the only highly successful bearing material that can combine low wear rates and the manufacturing of a thin acetabular component to preserve bone and still accommodate the large femoral head of a hip resurfacing. The adverse local tissue reactions (ALTR) associated with metal-on-metal devices are not a bearing material issue per se but one of the device design and surgical technique. Almost all of ALTR and the rare events of systemic toxicity are due to abnormal wear patterns which can be prevented by proper acetabular component design and precise socket orientation in both the coronal and sagittal planes. Further improvements of the long-term durability with hip resurfacing can be anticipated with the use of recently developed trabecular bone-like tantalum or titanium porous coatings and with proper training of the surgeons interested in performing hip resurfacing arthroplasty.
Peripheral Sympathectomy as a Novel Treatment Option for Distal Digital Necrosis following Parenteral Administration of Promethazine
Authors: Cross Michael B. , Warner Kristin , Young Kimberly , Weiland Andrew J.
Published: January 2013

Promethazine is a commonly used medication to treat nausea and motion sickness. Case reports have recently surfaced on the dangers of parenteral administration of promethazine. We present a case report of a presumed intravenous injection of promethazine into an antecubital intravenous line resulting in necrosis of the ring finger distal to the DIP joint and hypoperfusion of the digits. Peripheral sympathectomy was performed to improve nutritional flow and improve ischemic pain. However, although this novel treatment option was successful, ultimately the patient had an amputation of her ring finger at the level of her middle phalanx. Although no proven successful treatment exists, the updated treatment options following inadvertent intra-arterial or perivascular administration are presented. Given the limited success of current treatment options for intra-arterial or perivascular extravasation, the staggering medical malpractice awards in such cases, and the numerous therapeutic alternatives to promethazine, the medical community should question the safety and continued administration of promethazine by an intravenous route.
Metal-on-Metal Bearing: Is this the End of the Line? We Do Not Think So
Authors: Migaud Henri , Putman Sophie , Combes Antoine , Berton Charles , Bocquet Donatien , Vasseur Laurent , Girard Julien
Published: January 2013

Background

Recent studies have recommended the discontinuation of metal-on-metal (MoM) components in total hip arthroplasty (THA) because of adverse effects reported with large-diameter MoM THA. This is despite favorable long-term results observed with 28 and 32 mm MoM bearings.

Questions/purposes

The aim of this study was to assess the value of calls for an end to MoM bearings as THA components. Specifically, we wish to address the risks associated with MoM bearings including adverse soft tissue reactions, metal ion release, and carcinogenic risk.

Methods

The study evaluates the arguments in the literature reporting on MoM (adverse soft tissue reactions, metal ion release, and carcinogenic risk) and the experience of the current authors who re-introduced these bearings in 1995. They are balanced by a benefit–risk review of the literature and the authors’ experience with MoM use.

Results

Adverse reactions to metallic debris as well as metal ion release are predictable and can be prevented by adequate design (arc of coverage, clearance), metallurgy (forged instead of cast alloy, high-carbide content), and appropriate component orientation. There is no scientific evidence that carcinogenicity is increased in subjects with MoM hip prostheses. MoM articulations appear to be attractive allowing safe hip resurfacing, decreasing the risk of THA revision in active patients, and providing secure THA fixation with cement in cages in severely deformed hips. MoM bearings in women of child-bearing age are controversial, but long-term data on metallic devices in adolescents undergoing spinal surgery seem reassuring.

Discussion

Adequate selection of MoM articulations ensures their safe use. These articulations are sensitive to orientation. Fifteen years of safe experience with 28- and 32-mm bearings of forged alloy and high-carbide content is the main reason for retaining them in primary and revision THA.
Hip Arthroscopy: The Use of Computer Assistance
Authors: Nawabi Danyal H. , Nam Denis , Park Caroline , Ranawat Anil S.
Published: January 2013

Background

Hip arthroscopy is rapidly becoming the mainstay of treatment for femoroacetabular impingement (FAI), but remains technically demanding and has its limitations. The failures of arthroscopic FAI surgery due to inaccurate and inadequate resection are reported to be increasing. Computer-assisted surgery (CAS) can theoretically improve the accuracy and precision of the osseous resections required to treat FAI. It does so by providing a preoperative assessment tool, an intraoperative tracking device, and a robotic-assisted cutting instrument.

Questions/Purposes

The purpose of this review is to discuss the evolution of CAS to address the current limitations of arthroscopic FAI surgery and propose the features required of the ideal CAS solution for FAI.

Methods

A computerized keyword search of MEDLINE was performed for studies that investigated the use of computer assistance in FAI surgery. Data was collected on preoperative assessment tools, intraoperative navigation programs, and robotic-assisted execution of FAI surgery.

Results

Sixty-one articles were identified after the keyword search. Nineteen studies met our inclusion criteria. Thirteen studies were selected to address our study questions: three studies were analyzed for preoperative planning, six for navigated osseous resection, and four for robotic-assisted execution.

Conclusion

Navigation and robotic-assisted surgery can preoperatively plan and execute osseous resection with greater accuracy compared to freehand techniques, although the clinical success and cost-effectiveness has yet to be demonstrated. The ideal CAS solution must be able to virtually plan a resection, guide the surgeon towards accurate execution of the plan, and facilitate post-resection assessment of the adequacy of resection.
Educational Differences in Completed Fertility: A Behavioral Genetic Study of Finnish Male and Female Twins
Authors: Nisén Jessica , Martikainen Pekka , Kaprio Jaakko , Silventoinen Karri
Published: January 2013

Despite the large body of research on educational differences in fertility, how genetic and environmental influences may contribute to educational differences in completed fertility is not well understood. This study examines the association between educational level and completed fertility in a sample of Finnish male and female twins born between 1950 and 1957 with register-based fertility follow-up until 2009. The results show that poorly educated men and highly educated women are least likely to have any children and have lower completed fertility in general. Behavioral genetics analysis suggests that the association between education and having any children in both sexes is influenced by factors shared by co-twins and that these factors are genetic rather than common environmental. No evidence of a causal pathway between education and having any children independent of these shared influences is found. These findings suggest that familial factors may play a role in the process through which educational differences in completed fertility are formed.
A feedback regulation between Kindlin‐2 and GLI1 in prostate cancer cells
Authors: Gao Jianchao , Khan Ammad Aslam , Shimokawa Takashi , Zhan Jun , Strömblad Staffan , Fang Weigang , Zhang Hongquan
Published: January 2013

Kindlin‐2 is engaged in tumor progression. However, the mechanism accounting for Kindlin‐2 regulation in tumor cells remained largely unknown. Here, we report a regulatory loop between Kindlin‐2 and GLI1, an effector of Hedgehog signaling pathway. We show that Kindlin‐2 is transcriptionally downregulated via GLI1 occupancy on the Kindlin‐2 promoter. Adversely, we found that Kindlin‐2 promotes GLI1 expression through a mechanism involving GSK3β inactivation and is independent of Smoothened. Functionally, knockdown of Kindlin‐2 cooperates with cyclopamine, a Smoothened antagonist, to decrease the viability of prostate cancer cells. Taken together, targeting the Kindlin‐2–GLI1 feedback loop may facilitate the killing of prostate cancer cells.
A retrospective review of abdominal wall endometriosis in Shanghai, China
Authors: Ding Yan , Zhu Jin
Published: January 2013

Objective

To quantify the demographic characteristics, symptoms, and outcomes of women with abdominal wall endometriosis (AWE) in order to identify the optimal treatment and prevention techniques for AWE in the Chinese population.

Methods

In a retrospective study, women diagnosed with AWE at the Gynecology Hospital of Fudan University, Shanghai, China, between January 2003 and December 2011 were identified from the hospital's medical records. Data on patient age, previous surgeries, symptoms, asymptomatic time interval, duration of complaints, mass location, size, tenderness, diagnosis, treatment, and recurrence were analyzed.

Results

During the study period, 229 women were diagnosed with AWE, and histopathologic confirmation was obtained for 227 women (mean age, 31.7 ± 3.8 years). Each of these patients had undergone previous surgery, and 14 had undergone resection for AWE. The primary symptoms were pain, either cyclical (65.2%) or noncyclical (27.3%), and presence of a mass (84.1%; mean diameter, 2.9 ± 1.3 cm). The mean time interval between previous surgery and onset of symptoms was 2.3 ± 2.2 years. For all patients, the abdominal mass was surgically excised. The postoperative recurrence rate was 1.5%.

Conclusion

Complete resection is the primary treatment for AWE. A combination of surgical re‐excision and postoperative adjuvant medical therapy is recommended for patients with recurrent AWE.
Nutrition economics – food as an ally of public health
Authors: Lenoir-Wijnkoop I. , Jones P. J. , Uauy R. , Segal L. , Milner J.
Published: January 2013

Non-communicable diseases (NCD) are a major and increasing contributor to morbidity and mortality in developed and developing countries. Much of the chronic disease burden is preventable through modification of lifestyle behaviours, and increased attention is being focused on identifying and implementing effective preventative health strategies. Nutrition has been identified as a major modifiable determinant of NCD. The recent merging of health economics and nutritional sciences to form the nascent discipline of nutrition economics aims to assess the impact of diet on health and disease prevention, and to evaluate options for changing dietary choices, while incorporating an understanding of the immediate impacts and downstream consequences. In short, nutrition economics allows for generation of policy-relevant evidence, and as such the discipline is a crucial partner in achieving better population nutritional status and improvements in public health and wellness. The objective of the present paper is to summarise presentations made at a satellite symposium held during the 11th European Nutrition Conference, 28 October 2011, where the role of nutrition and its potential to reduce the public health burden through alleviating undernutrition and nutrition deficiencies, promoting better-quality diets and incorporating a role for functional foods were discussed.
Prospective study of alcohol consumption and the incidence of the metabolic syndrome in US men
Authors: Stoutenberg Mark , Lee Duck-chul , Sui Xuemei , Hooker Steven , Horigian Viviana , Perrino Tatiana , Blair Steven
Published: January 2013

Few studies have evaluated the effects of alcohol consumption on the incidence of the metabolic syndrome (MetS). Therefore, the objective of the present study was to examine the association between alcohol consumption and incident MetS in a population of US men. This is a prospective study of 7483 Caucasian men, who were free of the MetS and CVD at baseline. Information was collected on alcohol consumption, health status and fitness level at an initial clinical examination. Additional health information and determination of incident cases of the MetS were obtained at follow-up clinical examinations between 1979 and 2005. Compared with non-drinkers, the multivariate hazard ratios of the MetS for light (1–3 drinks/week), moderate (4–7 drinks/week), moderate–heavy (8–13 drinks/week) and heavy ( ≥ 14 drinks/week) drinkers were 0·81 (95 % CI 0·68, 0·95), 0·68 (95 % CI 0·57, 0·80), 0·70 (95 % CI 0·59, 0·83) and 0·78 (95 % CI 0·66, 0·91), respectively. This association was seen across age groups, in men with one or more pre-existing MetS risk factors, and those with BMI ≥ 25 kg/m2, and in all alcohol beverage types at most levels of alcohol consumption. An inverse dose–response association between alcohol consumption and low HDL concentrations was observed, while significant associations were observed between high fasting glucose concentrations and moderate, moderate–heavy and heavy levels of alcohol consumption. Alcohol consumption was not significantly associated with central obesity, hypertriacylglycerolaemia or hypertension. All levels of alcohol consumption provided significant inverse associations with incidence of the MetS. In particular, this effect was observed in overweight and/or obese individuals, in those who had pre-existing risk factors for the MetS, and extended across all types of alcoholic beverages consumed.
The Logic of Pro-Poor Policymaking: Political Entrepreneurship and Mass Education
Authors: Kosack Stephen
Published: January 2013

This article argues against the scholarly consensus that governments make pro-poor policies when they are democratic. In democracies and autocracies, a government's strongest incentive is to serve citizens who are organized, and poor citizens face collective-action disadvantages. But a ‘political entrepreneur’ can help poor citizens organize and attain power with their support; to stay in power, the political entrepreneur's incentive is to maintain poor citizens’ support with pro-poor policies. Politics and education are analyzed over half-a-century in countries with little in common – Ghana, Taiwan, and Brazil. Governments that expanded education for the poor were more often autocratic than democratic, but were always clearly associated with political entrepreneurs. The results suggest an alternative understanding of government incentives to serve poor citizens.
Remating behavior in Anastrepha fraterculus (Diptera: Tephritidae) females is affected by male juvenile hormone analog treatment but not by male sterilization
Authors: Abraham S. , Liendo M.C. , Devescovi F. , Peralta P.A. , Yusef V. , Ruiz J. , Cladera J.L. , Vera M.T. , Segura D.F.
Published: January 2013

The sterile insect technique (SIT) has been proposed as an area-wide method to control the South American fruit fly, Anastrepha fraterculus (Wiedemann). This technique requires sterilization, a procedure that affects, along with other factors, the ability of males to modulate female sexual receptivity after copulation. Numerous pre-release treatments have been proposed to counteract the detrimental effects of irradiation, rearing and handling and increase SIT effectiveness. These include treating newly emerged males with a juvenile hormone mimic (methoprene) or supplying protein to the male's diet to accelerate sexual maturation prior to release. Here, we examine how male irradiation, methoprene treatment and protein intake affect remating behavior and the amount of sperm stored in inseminated females. In field cage experiments, we found that irradiated laboratory males were equally able to modulate female remating behavior as fertile wild males. However, females mated with 6-day-old, methoprene-treated males remated more and sooner than females mated with naturally matured males, either sterile or wild. Protein intake by males was not sufficient to overcome reduced ability of methoprene-treated males to induce refractory periods in females as lengthy as those induced by wild and naturally matured males. The amount of sperm stored by females was not affected by male irradiation, methoprene treatment or protein intake. This finding revealed that factors in addition to sperm volume intervene in regulating female receptivity after copulation. Implications for SIT are discussed.
Using Citizenship to Retain Identity: The Native American Dance Bans of the Later Assimilation Era, 1900–1933
Authors: TREGLIA GABRIELLA
Published: January 2013

From the 1880s until the early 1930s the US federal government adopted a formal policy of intolerance towards Native American cultures and religions, stemming primarily from the belief that traditional religio-cultural practices – especially dances – distracted Native Americans from crop-tending and stock-rearing, and also constituted “outmoded” reminders of a “savage” past seen as incompatible with the responsibilities of US citizenship. Some cultural practices were banned outright, while others were actively discouraged or denigrated as “oldtime.” Yet Native American cultural expression did not die – in large part because Native communities employed varied methods to resist the bans. This article examines the ways in which pro-dancing communities utilized the language of US citizenship and made appeals to the Constitution, private property rights and US patriotism in their bid to ensure the survival of their dances and ceremonies. It also examines support for the dance bans by Native individuals, and the increasingly complex and evolving cultural identities in reservation communities in the early twentieth century.
Cyclic patterns of cerebral malaria admissions in Papua New Guinea for the years 1987–1996
Authors: DIMITROV B. D. , VALEV D. , WERNER R. , ATANASSOVA P. A.
Published: January 2013

Data on the dynamics of malaria incidence, admissions and mortality and their best possible description are very important to better forecast and assess the implementation of programmes to register, monitor (e.g. by remote sensing) and control the disease, especially in endemic zones. Semi-annual and seasonal cycles in malaria rates have been observed in various countries and close similarity with cycles in the natural environment (temperature, heliogeophysical activity, etc.), host immunity and/or virulence of the parasite suggested. This study aimed at confirming previous results on malaria cyclicity by exploring whether trans-year and/or multiannual cycles might exist. The exploration of underlying chronomes (time structures) was done with raw data (without smoothing) by linear and nonlinear parametric regression models, autocorrelation, spectral (Fourier) and periodogram regression analysis. The strongest cyclical patterns of detrended malaria admissions were (i) annual period of 1·0 year (12 months or seasonality); (ii) quasi-biennial cycle of about 2·25 years; and (iii) infrannual, circadecennial cycle of about 10·3 years. The seasonal maximum occurred in May with the minimum in September. Notably, these cycles corresponded to similar cyclic components of heliogeophysical activity such as sunspot seasonality and solar activity cyclicities and well-known climate/weather oscillations. Further analyses are thus warranted to investigate such similarities. In conclusion, multicomponent cyclical dynamics of cerebral malaria admissions in Papua New Guinea were observed thus allowing more specific analyses and modelling as well as correlations with environmental factors of similar cyclicity to be explored. Such further results might also contribute to and provide more precise estimates for the forecasting and prevention, as well as the better understanding, of the dynamics and aetiology of this vector-borne disease.
Current state of palliative and end-of-life care in home versus inpatient facilities and urban versus rural settings in Africa
Authors: Jang Jessica , Lazenby Mark
Published: January 2013

Objective:

Because palliative care in sub-Saharan Africa may not fit the style of delivery of palliative care in the global north, exploring the evidence can serve to reduce existing barriers and help streamline national policies that determine the optimal setting to implement formal palliative and end-of-life services.

Method:

A search was conducted in Ovid MEDLINE®, PubMed, and Google Scholar databases using the search terms nursing care, terminal care, end of life care, palliative care, dying, death, hospice, opioids, morphine, Africa, sub-Saharan Africa, caregivers, and place of death. Eighty-seven relevant articles were found using the search terms. Of these, 22 matched inclusion criteria and were reviewed.

Results:

Opioid availability and distribution is best accessed at the inpatient level, and hence, pain and end-of-life symptoms are best managed at the inpatient level. Despite the great need, nurses’ lack of prescription power in the home-based setting is a shortcoming. Home deaths have not been adequately studied, but research suggests that palliative care generally causes economic strain, psychosocial distress on family members, and increased risk of transmission of communicable disease. Hospice is understudied but shows favorable outcomes.

Significance of results:

Funding and research need to focus on development of inpatient palliative and hospice care units in urban areas. In rural areas, the priority should be a home-based care model that involves nurses who are privileged to prescribe opioids and adjunctive medication therapies.
Low-power CMOS LNA based on dual resistive-feedback structure with peaking inductor for wideband application
Authors: Hsu Meng-Ting , Hsu Shih-Yu , Lin Yu-Hwa
Published: January 2013

This paper presents a low-power and low-noise amplifier (LNA) with resistive-feedback configuration. The design consists of two resistive-feedback amplifiers. In order to reduce the chip area, a resistive-feedback inverter is adopted for input matching. The output stage adopts basic topology of an RC feedback for output matching, and adds two inductors for inductive peaking at the high band. The implemented LNA has a peak gain of 10.5 dB, the input reflection coefficient S11is lower than −8 dB and the output reflection S22is lower than −10.8 dB, and noise figure of 4.2–5.2 dB is between 1 and 10 GHz while consuming 12.65 mW from a 1.5 V supply. The chip area is only 0.69 mm2and the figure of merit is 6.64 including the area estimation. The circuit was fabricated in a TSMC 0.18 um CMOS process.
ICAT is a novel Ptf1a interactor that regulates pancreatic acinar differentiation and displays altered expression in tumours
Authors: Campos M. Luisa , Sánchez-Arévalo Lobo Víctor J. , Rodolosse Annie , Gottardi Cara J. , Mafficini Andrea , Beghelli Stefania , Scardoni Maria , Bassi Claudio , Scarpa Aldo , Real Francisco X.
Published: January 2013

The PTF1 (pancreas transcription factor 1) complex is a master regulator of differentiation of acinar cells, responsible for the production of digestive enzymes. In the adult pancreas, PTF1 contains two pancreas-restricted transcription factors: Ptf1a and Rbpjl. PTF1 recruits P/CAF [p300/CREB (cAMP-response-element-binding protein)-binding protein-associated factor] which acetylates Ptf1a and enhances its transcriptional activity. Using yeast two-hybrid screening, we identified ICAT (inhibitor of β-catenin and Tcf4) as a novel Ptf1a interactor. ICAT regulates the Wnt pathway and cell proliferation. We validated and mapped the ICAT–Ptf1a interaction in vitro and in vivo. We demonstrated that, following its overexpression in acinar tumour cells, ICAT regulates negatively PTF1 activity in vitro and in vivo. This effect was independent of β-catenin and was mediated by direct binding to Ptf1a and displacement of P/CAF. ICAT also modulated the expression of Pdx1 and Sox9 in acinar tumour cells. ICAT overexpression reduced the interaction of Ptf1a with Rbpjl and P/CAF and impaired Ptf1a acetylation by P/CAF. ICAT did not affect the subcellular localization of Ptf1a. In human pancreas, ICAT displayed a cell-type-specific distribution; in acinar and endocrine cells, it was nuclear, whereas in ductal cells, it was cytoplasmic. In ductal adenocarcinomas, ICAT displayed mainly a nuclear or mixed distribution and the former was an independent marker of survival. ICAT regulates acinar differentiation and it does so through a novel Wnt pathway-independent mechanism that may contribute to pancreatic disease.
Towards an optimized all lattice-matched InAlAs/InGaAsP/InGaAs multijunction solar cell with efficiency >50%
Authors: Leite Marina S. , Woo Robyn L. , Munday Jeremy N. , Hong William D. , Mesropian Shoghig , Law Daniel C. , Atwater Harry A.
Published: January 2013

An approach for an all lattice-matched multijunction solar cell optimized design is presented with 5.807 Å lattice constant, together with a detailed analysis of its performance by means of full device modeling. The simulations show that a (1.93 eV)In0.37Al0.63As/(1.39 eV)In0.38Ga0.62As0.57P0.43/(0.94 eV)In0.38Ga0.62As 3-junction solar cell can achieve efficiencies >51% under 100-suns illumination (with Voc = 3.34 V). As a key proof of concept, an equivalent 3-junction solar cell lattice-matched to InP was fabricated and tested. The independently connected single junction solar cells were also tested in a spectrum splitting configuration, showing similar performance to a monolithic tandem device, with Voc = 1.8 V.
A hierarchy of topological tensor network states
Authors: Buerschaper Oliver , Mombelli Juan Martín , Christandl Matthias , Aguado Miguel
Published: January 2013

We present a hierarchy of quantum many-body states among which many examples of topological order can be identified by construction. We define these states in terms of a general, basis-independent framework of tensor networks based on the algebraic setting of finite-dimensional Hopf C*-algebras. At the top of the hierarchy we identify ground states of new topological lattice models extending Kitaev's quantum double models [Ann. Phys. 303, 2 (2003)10.1016/S0003-4916(02)00018-0]. For these states we exhibit the mechanism responsible for their non-zero topological entanglement entropy by constructing an entanglement renormalization flow. Furthermore, we argue that the hierarchy states are related to each other by the condensation of topological charges.
Solvation at nanoscale: Alkali-halides in water clusters
Authors: Partanen Leena , Mikkelä Mikko-Heikki , Huttula Marko , Tchaplyguine Maxim , Zhang Chaofan , Andersson Tomas , Björneholm Olle
Published: January 2013

The solvation of alkali-halides in water clusters at nanoscale is studied by photoelectron spectroscopy using synchrotron radiation. The Na 2p, K 3p, Cl 2p, Br 3d, and I 4d core level binding energies have been measured for salt-containing water clusters. The results have been compared to those of alkali halide clusters and the dilute aqueous salt solutions. It is found that the alkali halides dissolve in small water clusters as ions.
Are rare, long waiting times between rearrangement events responsible for the slowdown of the dynamics at the glass transition?
Authors: Ahn Ji Won , Falahee Bryn , Piccolo Chiara Del , Vogel Michael , Bingemann Dieter
Published: January 2013

The dramatic slowdown of the structural relaxation at the glass transition is one of the most puzzling features of glass dynamics. Single molecule orientational correlation times show this strong Vogel-Fulcher-Tammann temperature dependence typical for glasses. Through statistical analysis of single molecule trajectories, we can identify individual glass rearrangement events in the vicinity of a probe molecule in the glass former poly(vinyl acetate) from 8 K below to 6 K above the glass transition temperature. We find that changes in the distribution of waiting times between individual glass rearrangement events are much less dramatic with temperature, the main difference being a small, but decisive number of increasingly long waiting times at lower temperatures. We notice similar individual, local relaxation events in molecular dynamics trajectories for a variety of glassy systems further from the glass transition, leading to waiting time distributions with similar features as those observed in the single molecule experiments. We show that these rare long waiting times are responsible for the dramatic increase in correlation time upon cooling.
Simple electrolyte solutions: Comparison of DRISM and molecular dynamics results for alkali halide solutions
Authors: Joung In Suk , Luchko Tyler , Case David A.
Published: January 2013

Using the dielectrically consistent reference interaction site model (DRISM) of molecular solvation, we have calculated structural and thermodynamic information of alkali-halide salts in aqueous solution, as a function of salt concentration. The impact of varying the closure relation used with DRISM is investigated using the partial series expansion of order-n (PSE-n) family of closures, which includes the commonly used hypernetted-chain equation (HNC) and Kovalenko-Hirata closures. Results are compared to explicit molecular dynamics (MD) simulations, using the same force fields, and to experiment. The mean activity coefficients of ions predicted by DRISM agree well with experimental values at concentrations below 0.5 m, especially when using the HNC closure. As individual ion activities (and the corresponding solvation free energies) are not known from experiment, only DRISM and MD results are directly compared and found to have reasonably good agreement. The activity of water directly estimated from DRISM is nearly consistent with values derived from the DRISM ion activities and the Gibbs-Duhem equation, but the changes in the computed pressure as a function of salt concentration dominate these comparisons. Good agreement with experiment is obtained if these pressure changes are ignored. Radial distribution functions of NaCl solution at three concentrations were compared between DRISM and MD simulations. DRISM shows comparable water distribution around the cation, but water structures around the anion deviate from the MD results; this may also be related to the high pressure of the system. Despite some problems, DRISM-PSE-n is an effective tool for investigating thermodynamic properties of simple electrolytes.
Analytic model of electromagnetic fields around a plasma bubble in the blow-out regime
Authors: Yi S. A. , Khudik V. , Siemon C. , Shvets G.
Published: January 2013

An analytic model of the electric and magnetic fields surrounding the nonlinear plasma “bubble” formed around the high-current electron bunch in a plasma wakefield accelerator is developed. The model, justified by the results of particle-in-cell simulations, accurately captures the thin high-density plasma sheath and extended return current layer surrounding the bubble. The resulting global fields inside and outside the bubble are used to investigate electron self-injection in a plasma with a smooth density gradient. It is shown that accurate description of the current/density sheaths is crucial for quantitative description of self-injection.
Multiscale approach combining nonadiabatic dynamics with long-time radiative and non-radiative decay: Dissociative ionization of heavy rare-gas tetramers revisited
Authors: Janeček Ivan , Janča Tomáš , Naar Pavel , Kalus René , Gadea Florent Xavier
Published: January 2013

A multiscale approach is proposed to address short-time nonadiabatic dynamics and long-time decay. We show the role of both radiative and non-radiative processes in cluster decay mechanisms on examples of rare-gas cluster fragmentation after electron impact ionization. Nonadiabatic molecular dynamics is used as an efficient tool for theoretical study on femto- and picosecond scales and a multiscale approach based on kinetic rates of radiative as well as non-radiative transitions, both considered as parallel reaction channels, is used for the analysis of the long-time system relaxation spanning times over microseconds to infinity. While the radiative processes are typically slow, the system relaxation through non-radiative electronic transitions connected with electron-nuclear interchange of energy may, on the other hand, significantly vary in kinetic rates according to kinetic couplings between relevant adiabatic states. While the predictions of picosecond molecular dynamics themselves fail, the results of the multiscale model for the electron-impact post-ionization fragmentation of krypton and xenon tetramers are in agreement with experiment, namely, in leading to the conclusion that charged monomers prevail. More specifically, on microsecond and longer scales, mainly slow radiative processes are substantial for krypton cluster decay, while for xenon the radiative and slow non-radiative processes compete. In general, the role of slow decay processes through non-radiative transitions is comparable with the role of radiative decay mechanism. The novel multiscale model substantially improves theoretical predictions for the xenon tetramer decay and also further improves the good agreement between theory and experiment we reached previously for krypton.
Ion current rectification inversion in conic nanopores: Nonequilibrium ion transport biased by ion selectivity and spatial asymmetry
Authors: Yan Yu , Wang Lin , Xue Jianming , Chang Hsueh-Chia
Published: January 2013

We show both theoretically and experimentally that the ion-selectivity of a conic nanopore, as defined by a normalized density of the surface charge, significantly affects ion current rectification across the pore. For weakly selective negatively charged pores, intra-pore ion transport controls the current and internal ion enrichment/depletion at positive/reverse biased voltage (current enters/leaves through the tip, respectively), which is responsible for current rectification. For strongly selective negatively charged pores under positive bias, the current can be reduced by external field focusing and concentration depletion at the tip at low ionic strengths and high voltages, respectively. These external phenomena produce a rectification inversion for highly selective pores at high (low) voltage (ionic strength). With an asymptotic analysis of the intra-pore and external ion transport, we derive simple scaling laws to quantitatively capture empirical and numerical data for ion current rectification and rectification inversion of conic nanopores.
Nonlinear dynamics of beta-induced Alfvén eigenmode in tokamak
Authors: Zhang H. S. , Lin Z. , Deng W. , Holod I. , Wang Z. X. , Xiao Y. , Zhang W. L.
Published: January 2013

The beta-induced Alfvén eigenmode (BAE) excited by energetic particles in toroidal plasmas is studied in the global gyrokinetic simulations. It is found that the nonlinear BAE dynamics depends on the deviation from the marginality. In the strongly driven case, the mode exhibits a bursting state with fast and repetitive chirping. The nonlinear saturation is determined by the thermal ion nonlinearity and has no clear dependence on the linear growth rate. In the weakly driven case, the mode reaches a nearly steady state with small frequency chirping. The nonlinear dynamics is dominated by the energetic particle nonlinearity. In both cases, the nonlinear intensity oscillation and frequency chirping are correlated with the evolution of the coherent structures in the energetic particle phase space. Due to the radial variation of the mode amplitude and the radially asymmetric guiding center dynamics, the wave-particle interaction in the toroidal geometry is much more complex than the conventional one-dimensional wave-particle interaction paradigm.
A density functional theory for patchy colloids based on Wertheim's association theory: Beyond the single bonding condition
Authors: Marshall Bennett D. , Chapman Walter G.
Published: January 2013

In the framework of Wertheim's theory, we develop the first classical density functional theory for patchy colloids where the patch can bond more than once. To test the theory we perform new Monte Carlo simulations for the model system of patchy colloids in a planar slit pore. The theory is shown to be in excellent agreement with simulation for the density profiles and bonding fractions. It is also shown that the theory obeys the wall contact rule by accurately predicting bulk pressures from the wall contact density.
Current-perpendicular-to-plane giant magnetoresistance using Co2Fe(Ga1−xGex) Heusler alloy
Authors: Goripati H. S. , Furubayashi T. , Takahashi Y. K. , Hono K.
Published: January 2013

We investigated the current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) of pseudo spin valves (PSVs) using ferromagnetic (FM) Heusler alloy Co2Fe(Ga1−xGex) (x = 0, 0.5, and 1) layers and an Ag spacer layer. The FM layer with x = 0.5 gave rise to the highest MR output, ΔRA = 8.7 mΩ·μm2, at room temperature with 10 nm thick Heusler alloy layers. The MR output increased with increasing annealing temperature, Ta, with a maximum at Ta = 500 °C. Transmission electron microscopy showed no visible changes in the layered structure; however, energy dispersive x-ray analysis indicated a considerable diffusion of Ga and Ge into the other layers by annealing at Ta = 550 °C. The ΔRA dependence on the thickness of the FM layers indicated that both high bulk and interface spin asymmetries contribute to the high MR output.
Divacancy-iron complexes in silicon
Authors: Tang C. K. , Vines L. , Markevich V. P. , Svensson B. G. , Monakhov E. V.
Published: January 2013

Iron and irradiation-induced defects have been investigated in p-type float-zone silicon after MeV electron-irradiation using deep level transient spectroscopy. Isochronal annealing (30 min) was performed up to 250 °C, and three distinctive energy levels are observed in the Fe-contaminated samples with positions of 0.25, 0.29, and 0.34 eV above the valence band edge, respectively. The two latter ones are found to accompany the change in concentration of the divacancy center (V2) during the isochronal annealing which strongly indicates an interaction between Fe and V2. Furthermore, the properties of the defects support recent theoretical predictions of FeV2 and VFeV (Estreicher et al., Phys. Rev. B 77, 125214 (2008)).
Iterative Boltzmann plot method for temperature and pressure determination in a xenon high pressure discharge lamp
Authors: Zalach J. , Franke St.
Published: January 2013

The Boltzmann plot method allows to calculate plasma temperatures and pressures if absolutely calibrated emission coefficients of spectral lines are available. However, xenon arcs are not very well suited to be analyzed this way, as there are only a limited number of lines with atomic data available. These lines have high excitation energies in a small interval between 9.8 and 11.5 eV. Uncertainties in the experimental method and in the atomic data further limit the accuracy of the evaluation procedure. This may result in implausible values of temperature and pressure with inadmissible uncertainty. To omit these shortcomings, an iterative scheme is proposed that is making use of additional information about the xenon fill pressure. This method is proved to be robust against noisy data and significantly reduces the uncertainties. Intentionally distorted synthetic data are used to illustrate the performance of the method, and measurements performed on a laboratory xenon high pressure discharge lamp are analyzed resulting in reasonable temperatures and pressures with significantly reduced uncertainties.
Designing phase-sensitive tests for Fe-based superconductors
Authors: Golubov A. A. , Mazin I. I.
Published: January 2013

We suggest experimental designs suitable to test pairing symmetry in multiband Fe-based superconductors. These designs are based on combinations of tunnel junctions and point contacts and should be accessible by existing sample fabrication techniques.
Characterization of thin AlSb/AlAs barriers on InAs by mid-infrared intersubband absorption measurements
Authors: Castellano Fabrizio , Ohtani Keita , Nevou Laurent , Faist Jerome
Published: January 2013

We present mid-infrared intersubband absorption measurements on InAs/AlSb coupled-quantum-wells systems with thin AlSb barriers. The AlSb barrier width in our samples is varied between 1 and 4 monolayers, with a strained AlAs boundary layer used for strain compensation. The optical absorption energy difference between the 1–4 and 2–3 transitions is used as a measure of the barrier coupling strength and modeled by a one-band Schroedinger solver. Our results let us conclude that the composite AlSb/AlAs barrier behaves like an effective AlSb barrier with an effective thickness that does not include the last As layer. This observation must be taken into account when designing complex heterostructures relying on very thin AlSb, like in InAs/AlSb quantum cascade lasers.
Quenching-induced circumvention of integrated aging effect of relaxor lead lanthanum zirconate titanate and (Bi1/2Na1/2)TiO3-BaTiO3
Authors: Zang Jiadong , Jo Wook , Rödel Jürgen
Published: January 2013

The effect of quenching on the dielectric properties of ceramic Pb0.92La0.08(Zr0.65Ti0.35)0.98O3 (PLZT 8/65/35) and (Bi1/2Na1/2)TiO3-6 mol. %BaTiO3 (BNT-6BT) was investigated after annealing at a wide range of temperatures. The dielectric permittivity showed that the magnitude and shape profile of the permittivity were significantly affected by the quenching process in comparison to furnace-cooled specimens. We propose that the changes originate from a circumvention of integrated aging that takes place during cooling process. A comparison between PLZT 8/65/35 and BNT-6BT allowed us to conclude that two different types of polar nanoregions exist in BNT-6BT and the transition between them peaks at around 300 °C.
Transferrable Learning of Multisensory Cues in Flight Simulation
Authors: Meyer Georg F , Wong Li , Timson Emma , Perfect Philip , White Mark
Published: January 2013

Flight simulators which provide visual, auditory, and kinematic (physical motion) cues are increasingly used for pilot training. We have previously shown that kinematic cues, but not auditory cues, representing aircraft motion improve target tracking performance for novice ‘pilots’ in a simulated flying task (Meyer et al IMRF 2010). Here we explore the effect of learning on task performance. Our subjects were first tested on a target tracking task in a helicopter flight simulation. They were then trained in a simulator-simulator, which provided full audio, simplified visuals, but not kinematic signals to test whether learning of auditory cues is possible. After training we evaluated flight performance in the full simulator again. We show that after 2 hours training auditory cues are used by our participants as efficiently as kinematic cues to improve target tracking performance. The performance improvement relative to a condition where no audio signals are presented is robust if the sound environment used during training is replaced by a very different audio signal that is modulated in amplitude and pitch in the same way as the training signal. This shows that training is not signal specific but that our participants learn to extract transferrable information on sound pitch and amplitude to improve their flying performance.
Effects of increasing supplementation levels of rice bran on milk production and fatty acid composition of milk in Saanen dairy goats
Authors: Park J. K. , Kwon E. G. , Kim C.-H.
Published: January 2013

In this study, the effects of four dietary supplementation levels of rice bran (RB) on milk yield and composition were examined in Saanen dairy goats. Four goats (initial bodyweight, 55.0 ± 7.1 kg) and four 21-day periods were used in a 4 × 4 Latin-square design. The diets contained 0, 5, 10, and 20% DM of RB, but were otherwise formulated to be 10.7 MJ metabolisable energy/kg and 18.8% crude protein/kg DM. Goats consumed the greatest amount of DM feed concentrate when fed the 5% RB diet (P < 0.01); however, DM forage intake was not significantly different between diets. Total DM intake of the 5% RB diet was significantly higher than that of the control diet (P < 0.05). Milk yield was the lowest from goats fed the 20% RB (P < 0.01). The protein concentration of milk was significantly lower in goats fed the control and 5% RB diets than in those fed the 10 and 20% RB diets (P < 0.01). However, milk protein production was not significantly different between diets. The concentration of fat in milk increased as the supplementation level of RB increased, although fat production did not differ between diets. The addition of RB increased the concentration of long-chain fatty acids (C16 and C18) in goat milk. No significant difference was found in milk lactose concentration between diets. Overall, the results indicate that RB supplements of up to 10% have no adverse effects on DM intake and milk production in dairy goats.