bluuebunny/crossref_metadata_2025 huggingface dataset:
Adjusting for confounding by neighborhood using complex survey data
Authors: Brumback Babette A. , He Zhulin
Published: February 2011

Recently, we examined methods of adjusting for confounding by neighborhood of an individual exposure effect on a binary outcome, using complex survey data; the methods were found to fail when the neighborhood sample sizes are small and the selection bias is strongly informative. More recently, other authors have adapted an older method from the genetics literature for application to complex survey data; their adaptation achieves a consistent estimator under a broad range of circumstances. The method is based on weighted pseudolikelihoods, in which the contribution from each neighborhood involves all pairs of cases and controls in the neighborhood. The pairs are treated as if they were independent, a pairwise pseudo‐conditional likelihood is thus derived, and then the corresponding score equation is weighted with inverse‐probabilities of sampling each case‐control pair. We have greatly simplified the implementation by translating the pairwise pseudo‐conditional likelihood into an equivalent ordinary weighted log‐likelihood formulation. We show how to program the method using standard software for ordinary logistic regression with complex survey data (e.g. SAS PROC SURVEYLOGISTIC). We also show that the methodology applies to a broader set of sampling scenarios than the ones considered by the previous authors. We demonstrate the validity of our simplified implementation by applying it to a simulation for which previous methods failed; the new method performs beautifully. We also apply the new method to an analysis of 2009 National Health Interview Survey (NHIS) public‐use data, to estimate the effect of education on health insurance coverage, adjusting for confounding by neighborhood. Copyright © 2011 John Wiley & Sons, Ltd.
Intact Mammalian Cell Function on Semiconductor Nanowire Arrays: New Perspectives for Cell‐Based Biosensing
Authors: Berthing Trine , Bonde Sara , Sørensen Claus B. , Utko Pawel , Nygård Jesper , Martinez Karen L.
Published: February 2011

Nanowires (NWs) are attracting more and more interest due to their potential cellular applications, such as delivery of compounds or sensing platforms. Arrays of vertical indium‐arsenide (InAs) NWs are interfaced with human embryonic kidney cells and rat embryonic dorsal root ganglion neurons. A selection of critical cell functions and pathways are shown not to be impaired, including cell adhesion, membrane integrity, intracellular enzyme activity, DNA uptake, cytosolic and membrane protein expression, and the neuronal maturation pathway. The results demonstrate the low invasiveness of InAs NW arrays, which, combined with the unique physical properties of InAs, open up their potential for cellular investigations.
Structured Graphene Devices for Mass Transport
Authors: Barreiro Amelia , Rurali Riccardo , Hernández Eduardo R. , Bachtold Adrian
Published: February 2011

The reversible atomic‐mass transport along graphene devices has been achieved. The motion of Al and Au in the form of atoms or clusters is driven by applying an electric field between the metal electrodes that contact the graphene sheet. It is shown that Al moves in the direction of the applied electric field whereas Au tends to diffuse in all directions. The control of the motion of Al is further demonstrated by achieving a 90° turn, using a graphene device patterned in a crossroads configuration. The controlled motion of Al is attributed to the charge transfer from Al onto the graphene so that the Al is effectively charged and can be accelerated by the applied electric field. To get further insight into the actuation mechanism, theoretical simulations of individual Al and Au impurities on a perfect graphene sheet were performed. The direct (electrostatic) force was found to be ∼1 pN and dominant over the wind force. These findings hold promise for practical use in future mass transport in complex circuits.
An energy‐efficient hole‐healing mechanism for wireless sensor networks with obstacles
Authors: Chang Chih‐Yung , Lin Chih‐Yu , Yu Gwo‐Jong , Kuo Chin‐Hwa
Published: February 2011

In wireless sensor networks (WSNs), coverage of the monitoring area represents the surveillance quality. Since sensor nodes are battery powered and placed outdoor, there will be failures due to energy exhaustion or environmental influence, resulting in coverage‐loss. In literature, a number of studies developed robot repairing algorithms that aim at maintaining full coverage. However, they did not consider the time constraint for network maintenance. Furthermore, they did not consider the existence of obstacles and the constraint of limited energy of the robot. This paper presents a novel tracking mechanism and robot repairing algorithm for maintaining the coverage quality of the given WSN. Without support of location information, the tracking mechanism leaves robot's footmark on sensors so that they can learn better routes for sending repairing requests to the robot. Upon receiving several repairing request messages, the robot applies the proposed repairing algorithm to establish an efficient route that passes through all failure regions with low overhead in terms of the required time and the power consumption. In addition, the proposed repairing algorithm also considers the remaining energy of the robot so that the robot can move back to home for recharging energy and overcome the unpredicted obstacles. Performance results reveal that the developed protocol can efficiently maintain the coverage quality while the required time and energy consumption are significantly reduced. Copyright © 2011 John Wiley & Sons, Ltd.
Two New Fatty Acid Derivatives from the Stem Bark ofAlchornea laxiflora(Euphorbiaceae)
Authors: Sandjo Louis Pergaud , Poumale Hervé M. Poumale , Siwe Xavier Noudou , Ntede Hippolyte Nga , Shiono Yoshihito , Ngadjui Bonaventure Tchaleu , Krause Rui M. W. , Ndinteh Derek Tantoh , Mbafor Joseph Tanyi
Published: February 2011

Euphorbiaceae is a family of plants used in traditional remedies in central Africa to treat selected diseases. Some of the phytochemical components in the stem bark ofAlchornea laxiflorathat have biochemical activity were identified. A number of novel compounds were isolated, including a new fatty acid ester, (1) a new ceramide, (2) some triterpenoids, (3–5), ellagic acid (6) and its derivatives (7,8) were isolated. The structures of these compounds were determined on the basis of spectroscopic methods as well as HR‐ESI‐TOF‐MS analysis, chemical transformation and by comparison of their physical and spectral data with those reported in the literature. The cytotoxicity of some isolated compounds was investigated against human promyelocytic leukaemia (HL60) cell line by using the MTT method. Compounds1,4and5showed a cytotoxic activity with IC50at 58.7, 6.6 and 6.8 μM, respectively.
Engaging Undergraduate Nursing Students in Perioperative Research
Authors: Taber Kimberly , Taber Renee , Galante Larissa , Sigsby Linda M.
Published: February 2011

Actively engaging in perioperative research lays a framework for stimulating interest in future research possibilities and provides students and graduate nurses with challenges to keep them interested as their careers progress. In this article, former honors students and a faculty researcher share their perceptions of participating in perioperative research. The primary investigator must emphasize learning throughout the process, be available to the students, provide structured guidance, and clarify the goals and expectations of the research experience. The students gain a greater understanding of the research process, discover the dedication and ethical values that are required of the researcher, learn how theory becomes the underlying framework for the research, and discover how descriptive statistics can be used to help explain the study results. Involvement in applied research may encourage these students to continue to contribute to evidence‐based practice when they are employed as nurses and thus improve patient care.
Intraoperative Monitoring Technician: A New Member of the Surgical Team
Authors: Brown Molly S. , Brown Debra S.
Published: February 2011

As surgery needs have increased, the traditional surgical team has expanded to include personnel from radiology and perfusion services. A new surgical team member, the intraoperative monitoring technician, is needed to perform intraoperative monitoring during procedures that carry a higher risk of central and peripheral nerve injury. Including the intraoperative monitoring technician on the surgical team can create challenges, including surgical delays and anesthesia care considerations. When the surgical team members, including the surgeon, anesthesia care provider, and circulating nurse, understand and facilitate this new staff member's responsibilities, the technician is able to perform monitoring functions that promote the smooth flow of the surgical procedure and positive patient outcomes.
The EKG Handbook
Authors: Rockhill Wayne
Published: February 2011

The EKG Handbook Theresa Ann Middleton Brosche 2010, Jones and Bartlett Publishers 250 pages, $37.95 spiral bound
Clinical Issues—February 2011
Authors: Denholm Bonnie G.
Published: February 2011

Calculating flash sterilization rates

Key words: flash sterilization, benchmarking.

Manual cleaning of instruments

Key words: manual cleaning, instrument decontamination, instrument sterilization, ultrasonic cleaning.

Water temperature for decontaminating instruments

Key words: manual cleaning process, mechanical cleaning, instrument decontamination, instrument sterilization.

Assessment of abuse

Key words: patient assessment, domestic violence, abuse, documentation, reporting, elder abuse, intimate partner violence, neglect, financial exploitation.
Mental state attribution in schizophrenia: What distinguishes patients with “poor” from patients with “fair” mentalising skills?
Authors: Brüne M. , Schaub D.
Published: February 2011

Purpose

Although many patients with schizophrenia are impaired in mental states attribution abilities, a significant number perform within normal or near-normal ranges in mental state attribution tasks. No studies have analysed cognitive or behavioural differences between patients with – to some extent – preserved mental state attribution skills and those with poor mentalising abilities.

Material and methods

To examine characteristics of “poor” and “fair” mentalisers, 58 patients with schizophrenia performed a mental state attribution task, a test of general intelligence, and two executive functioning tests. “Poor” and “fair” mentalising skills were defined according to a median-split procedure; the median score in the patient group was also within two standard deviations of the control group. In addition, patients’ social behavioural skills and psychopathological profiles were rated.

Results

Patients performing within normal or near normal ranges on the mental state attribution task had fewer social behavioural abnormalities than patients with poor mentalising abilities (even when controlled for intelligence), but did not differ in executive functioning. Fair mental state performers showed less disorganisation and excitement symptoms than poor performers. The degree of disorganisation mediated the influence of mental state attribution on social behavioural skills.

Conclusions

Schizophrenia patients with (partially) preserved mentalising skills have fewer behavioural problems in the social domain than patients with poor mentalising abilities. Conceptual disorganisation mediates the prediction of social behavioural skills through mentalising skills, suggesting that disorganised patients may require special attention regarding social-cognitive skills training.
Insular volume reduction in fragile X syndrome
Authors: Cohen Jeremy D. , Nichols Taylor , Brignone Laura , Hall Scott S. , Reiss Allan L.
Published: February 2011

Fragile X syndrome (FraX) is the most common form of inherited mental deficit and is caused by mutations of the Fragile X Mental Retardation 1 (FMR1) gene on the X chromosome. While males and females with the full FMR1 mutation are affected differently because the disorder is X‐linked, both suffer from varying degrees of cognitive impairment, attention deficits and social anxiety. The insula is a sensory integrative region that has been increasingly suggested as a critical area involved in anxiety manifestation.

The current study was designed to examine possible changes in insular volume in FraX compared to age‐ and gender‐matched typically developing healthy controls (HC) as well as age‐, gender‐, and intelligence‐matched developmentally delayed controls (DD). An established native‐space, manual morphometry method was utilized to quantify total and regional insular volumes using structural magnetic resonance imaging.

Total, anterior and posterior insular volumes were found to be reduced in FraX compared to both HC and DD. The current data add to a growing literature concerning brain abnormalities in FraX and suggests that significant volume reduction of the insula is a component of the FraX neuroanatomical phenotype. This finding also provides an intriguing potential neural correlate for hyperarousal and gaze aversion, which are prominent behavioral symptoms of FraX.
Nutzer des Gesundheitswesens zu Gesprächspartnern der Professionellen machen – das Konzept der Patientenuniversität an der Medizinischen Hochschule Hannover
Authors: Dierks Marie-Luise , Seidel Gabriele , Schwartz Friedrich Wilhelm
Published: February 2011

Einleitung

2006 wurde an der Medizinischen Hochschule Hannover (MHH) die erste deutsche Patientenuniversität gegründet. Sie ist ein unabhängiges, durch Eigenmittel, Teilnehmerbeiträge und Spenden finanziertes Bildungsinstitut, angesiedelt am Institut für Epidemiologie, Sozialmedizin und Gesundheitssystemforschung. Mit der Patientenuniversität reagiert die MHH auf die Anforderungen an Nutzer des Gesundheitswesens, sich in einem unübersichtlichen und zunehmend von Marktinteressen beherrschten Gesundheitswesen zu orientieren. Sie unterstützt die Menschen darin, selbstbewusste Partner in der Gesundheitsversorgung zu werden.
The ‘absolute existence’ of phlogiston: the losing party's point of view
Authors: BOANTZA VICTOR D. , GAL OFER
Published: February 2011

Long after its alleged demise, phlogiston was still presented, discussed and defended by leading chemists. Even some of the leading proponents of the new chemistry admitted its ‘absolute existence’. We demonstrate that what was defended under the title ‘phlogiston’ was no longer a particular hypothesis about combustion and respiration. Rather, it was a set of ontological and epistemological assumptions and the empirical practices associated with them. Lavoisier's gravimetric reduction, in the eyes of the phlogistians, annihilated the autonomy of chemistry together with its peculiar concepts of chemical substance and quality, chemical process and chemical affinity. The defence of phlogiston was the defence of a distinctly chemical conception of matter and its appearances, a conception which reflected the chemist's acquaintance with details and particularities of substances, properties and processes and his skills of adducing causal relations from the interplay between their complexity and uniformity.
Distribution and conservation status of the Vulnerable eastern hoolock gibbon Hoolock leuconedys in China
Authors: Peng-Fei Fan , Wen Xiao , Sheng Huo , Huai-Sen Ai , Tian-Can Wang , Ru-Tao Lin
Published: February 2011

We conducted an intensive survey of the Vulnerable eastern hoolock gibbon Hoolock leuconedys along the west bank of the Salween River in southern China, covering all known hoolock gibbon populations in China. We found 40–43 groups, with a mean group size of 3.9, and five solitary individuals. We estimated the total population to be < 200. In the nine groups for which we recorded composition, seven comprised one adult pair and 0–3 offspring and the other two groups both comprised one adult male and two adult females. The population is severely fragmented, in 17 locations, with the largest subpopulation containing only five family groups. Compared with the population in 1985 and 1994 five subpopulations have declined and gibbons have been extirpated from nine localities, although we discovered two previously unknown subpopulations. Commercial logging, illegal hunting, agricultural encroachment and population fragmentation pose serious threats to the future of H. leuconedys in China. An integrated conservation plan, including nature reserve establishment/expansion, enforcement of existing laws, conservation education, translocation and conservation-oriented research are needed to ensure the survival of H. leuconedys in China.
Twenty years of monitoring of the Vulnerable Farasan gazelle Gazella gazella farasani on the Farasan Islands, Saudi Arabia: an overview
Authors: Cunningham Peter Low , Wronski Torsten
Published: February 2011

The mountain gazelle Gazella gazella in Saudi Arabia is categorized as Vulnerable on the IUCN Red List. On the mainland the species’ survival depends on a few remnant populations in the western Mountains and coastal plains and on two reintroduced populations. The largest natural population of G. gazella in Saudi Arabia is the Farasan gazelle subspecies G. g. farasani, which inhabits the Farasan Islands in the Red Sea. We review and collate the available literature on this subspecies, mainly unpublished reports presenting wildlife census data, and supplement this with the most recent, 2009, count. The number of free-ranging gazelles has remained approximately constant since the first counts in 1988, with an overall density of 0.64 km-2 and an estimated population of 1,039 on Farasan Kebir in 2009. The populations on two other islands, As Saqid and Zifaf, have not fared as well, possibly because of uncontrolled hunting pressure, competition with domestic stock or poor habitat conditions overall. The population on Qummah Island is extinct. Threats to this subspecies include uncontrolled hunting and uncoordinated development. Continued protection of this apparently stable population of mountain gazelle in Saudi Arabia is imperative to ensure the survival of the species.
In uteroexposure to virus infections and the risk of developing anorexia nervosa
Authors: Favaro A. , Tenconi E. , Ceschin L. , Zanetti T. , Bosello R. , Santonastaso P.
Published: February 2011

Background

The study aims to explore, using indirect ecological measures of exposure, the role of viral infections in the development of anorexia nervosa (AN).

Method

The cohort of participants consisted of all female subjects born in the Veneto region in the period between 1970 and 1984, and residing in the urban and suburban area of Padua (27 682 female subjects in an area of 424 km2). The main outcome measure was the diagnosis of AN resulting from the Public Mental Health Database, the Register of Hospital Admissions, and the Register of the Eating Disorders Unit (n=402, 1.4%). The number of cases of rubella, chickenpox, influenza and measles was ascertained for each month for the 15-year period.

Results

Exposures during the sixth month of pregnancy to the peaks of chickenpox [odds ratio (OR) 1.6, 95% confidence interval (CI) 1.2–2.0] and rubella infections (OR 1.5, 95% CI 1.1–2.0) were significantly associated with an increased risk of developing AN, even after controlling for socio-economic status, urbanization and month of birth. We found weak evidence of a season-of-birth bias.

Conclusions

In uteroexposure to viral infection could be a risk factor for developing AN. We need further epidemiological and serological studies to confirm this hypothesis.
Asymmetry of salivary cortisol and α-amylase responses to psychosocial stress in anorexia nervosa but not in bulimia nervosa
Authors: Monteleone P. , Scognamiglio P. , Canestrelli B. , Serino I. , Monteleone A. M. , Maj M.
Published: February 2011

Background

The stress response involves the activation of the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS). As a role for stress in determining of the onset and the natural course of eating disorders (EDs) has been proposed, the study of the psychobiology of the stress response in patients with anorexia nervosa (AN) and bulimia nervosa (BN) should be helpful in understanding the pathophysiology of these disorders. The two neurobiological components of the stress response can be easily explored in humans by the measurement of salivary cortisol and α-amylase response to a stressor. Therefore, we assessed salivary cortisol and α-amylase responses to the Trier Social Stress Test (TSST) in symptomatic patients with AN and BN compared to healthy controls.

Method

Seven AN women, eight BN women and eight age-matched healthy females underwent the TSST between 1530 and 1700 h. Salivary cortisol and α-amylase levels were measured by an enzyme-linked immunosorbent assay (ELISA).

Results

Compared to healthy women, AN patients showed a normal cortisol response to the TSST, although this occurred at significantly increased hormone levels, and an almost complete absence of response of α-amylase. BN women, however, exhibited enhanced pre-stress levels of salivary α-amylase but a normal response of the enzyme and cortisol to the TSST.

Conclusions

These findings demonstrate, for the first time, the occurrence of an asymmetry between the HPA axis and SNS components of the stress response in the acute phase of AN but not in BN. The pathophysiological significance of this asymmetry remains to be determined.
High-resolution synchrotron X-ray diffraction studies of size and strain effects in a complex Al–Fe–Cr–Ti alloy
Authors: Hogg S. C. , Liotti E. , Kirk C. A. , Thompson S. P. , Parker J. E. , Grant P. S.
Published: February 2011

We present a study of a complex ultra-high-strength Al alloy containing ~40 volume per cent of second-phase particles, ranging in size from nanometres to a few microns. The microstructure has been investigated using scanning electron microscopy and high-resolution synchrotron X-ray diffraction using the I11 beam line at the Diamond Light Source, UK. Powder diffraction was carried out to (i) determine phases present, (ii) quantify the weight per cent of each phase and (iii) quantify size and strain effects in the Al matrix. The high beam quality (i.e. low divergence and wavelength purity) and multi-analysing crystal detectors makes this an ideal instrument to resolve the high peak density and determine the contribution of sample broadening in the complex alloy. Using Pawley and Rietveld full pattern fitting, the intermetallic phases present were determined to be Al3Ti, Al13Cr2 and Al13Fe4. The weight fraction of each phase was calculated from the Rietveld refinements and correlated well with thermodynamic calculations assuming an equilibrium microstructure. Size and strain in the Al matrix was measured from peak broadening using a Double Voigt analysis and showed significant physical broadening due to both size and strain.
Lokale Unterdrucktherapie im Wundmanagement in Institutionen der Langzeitpflege
Authors: Erlinger  , Bieri-Brüning
Published: February 2011

Unterdruckbehandlung in der Wundbehandlung wird bisher vor allem in Spitälern eingesetzt. Die durchschnittliche Aufenthaltsdauer in Akutspitäler wird voraussichtlich durch die Einführung der Fallkostenpauschalen in der Schweiz noch weiter sinken. Deshalb stellt sich die Frage, ob die Unterdruckbehandlung auch in Pflegeheimen angewendet werden soll, weil sie bei betagten Patienten oft die Anschlussbehandlung nach einer Akutbehandlung übernehmen. Aufgrund der Literatur formulieren die Autoren Empfehlungen für einen Einsatz der Unterdruckbehandlung in Pflegeheimen.
Nadelstichverletzungen beim Medizinalpersonal: Richtlinien und Realität
Authors: Kuhn  , Wertli
Published: February 2011

Für Mitarbeitende im Gesundheitswesen besteht ein erhöhtes Risiko für eine Exposition gegenüber potentiell infektiösen Blut- oder Körperflüssigkeiten. Neben Präventionsmassnahmen vor Expositionen sind Richtlinien bezüglich dem Verhalten nach einer stattgehabten Exposition erforderlich, um potentielle Infektionen mit HIV, HCV und HBV zu verhindern, bzw. frühzeitig zu erkennen und rechtzeitig zu behandeln. Dadurch können Morbidität und damit verbundene Kosten gesenkt werden. Die Umsetzung dieser Richtlinien ist in der Praxis aber nicht immer einfach.
45-jähriger Lehrer mit weissem Kleinfinger rechts
Authors: Clemens  , Husmann  , Amann-Vesti  , Thalhammer
Published: February 2011

Wir berichten über einen 45-jährigen Lehrer mit einer Fingerischämie der rechten Hand mit Kältegefühl und Weissverfärbung. Die nicht-invasive Diagnostik ergab ein Hypothenar-Hammer-Syndrom bei rezidivierenden Traumata im Bereich des Handballens durch berufliches Handwerken, durch regelmässige Bedienung einer Espressomaschine sowie durch gelegentliches Schlagzeugspielen. Wir diskutieren die diagnostischen Methoden, die Ätiologie und die möglichen Therapieoptionen.
Differential Correlates of Group and Organizational Collective Efficacy
Authors: Petitta Laura , Borgogni Laura
Published: February 2011

This study aimed at exploring the role of the context in shaping collective efficacy beliefs, at both group and organizational level, and their differential relationship with organizational commitment. Employees (N = 1,741) of a multinational financial company were administered a questionnaire measuring collective efficacy, perceptions of context (PoC), and organizational commitment. Two facets of collective efficacy were investigated, namely group and organizational, and their respective relationship with PoC and organizational commitment. Group and organizational efficacy were found to be two different dimensions of collective efficacy. Structural equation models supported the hypothesized relationship among variables. Perceptions of top management displayed a stronger relationship with collective efficacy at the organizational level, whereas perceptions of the direct superior were related to collective efficacy at the group level. Organizational collective efficacy had a stronger relationship with organizational commitment than did group collective efficacy.
The Reliability of Retrieval-Induced Forgetting
Authors: Potts Rosalind , Law Robin , F. Golding John , Groome David
Published: February 2011

Retrieval-induced forgetting (RIF) refers to the finding that the retrieval of an item from memory impairs the retrieval of related items. The extent to which this impairment is found in laboratory tests varies between individuals, and recent studies have reported an association between individual differences in the strength of the RIF effect and other cognitive and clinical factors. The present study investigated the reliability of these individual differences in the RIF effect. A RIF task was administered to the same individuals on two occasions (sessions T1 and T2), one week apart. For Experiments 1 and 2 the final retrieval test at each session made use of a category-cue procedure, whereas Experiment 3 employed category-plus-letter cues, and Experiment 4 used a recognition test. In Experiment 2 the same test items that were studied, practiced, and tested at T1 were also studied, practiced, and tested at T2, but for the remaining three experiments two different item sets were used at T1 and T2. A significant RIF effect was found in all four experiments. A significant correlation was found between RIF scores at T1 and T2 in Experiment 2, but for the other three experiments the correlations between RIF scores at T1 and T2 failed to reach significance. This study therefore failed to find clear evidence for reliable individual differences in RIF performance, except where the same test materials were used for both test sessions. These findings have important implications for studies involving individual differences in RIF performance.
Organizational Transactive Memory Systems
Authors: Peltokorpi Vesa
Published: February 2011

The transactive memory system (TMS) concept has been extended from dyads and groups to organizations. While organizational TMS literature helps to understand how employees locate and utilize information based on their awareness of “who knows what” and “who knows who,” conceptual development is beneficial because TMS has been extended to organizations without clear definitions and levels-of-analysis rationale. Drawing from the social psychology and network literature, this paper identifies several aspects requiring further conceptual attention, and defines organizational TMS as overlapping networks of interdependent work groups that use each other as external cognitive aids to accomplish shared tasks. Suggestions for managing and measuring organizational TMS are provided.
Transverse mixing of conservative and reactive tracers in porous media: Quantification through the concepts of flux‐related and critical dilution indices
Authors: Chiogna Gabriele , Cirpka Olaf A. , Grathwohl Peter , Rolle Massimo
Published: February 2011

The correct quantification of mixing is of utmost importance for modeling reactive transport in porous media and for assessing the fate and transport of contaminants in the subsurface. An appropriate measure of mixing in heterogeneous porous formations should correctly capture the effects on mixing intensity of various processes at different scales, such as local dispersion and the mixing enhancement due to heterogeneities. In this work, we use the concept of flux‐related dilution index as a measure of transverse mixing. This quantity expresses the dilution of the mass flux of a conservative tracer solution over the total discharge of the system, and is particularly suited to address problems where a compound is continuously injected into the domain. We focus our attention on two‐dimensional systems under steady state flow conditions and investigate both conservative and reactive transport in homogeneous and heterogeneous porous media at different scales. For mixing‐controlled reactive systems, we introduce and illustrate the concept of critical dilution index, which represents the amount of mixing required for complete degradation of a continuously emitted plume undergoing decay upon mixing with ambient water. We perform two‐dimensional numerical experiments at bench and field scales in homogeneous and heterogeneous conductivity fields. These numerical simulations show that the flux‐related dilution index quantifies mixing and that the concept of critical dilution index is a useful measure to relate the mixing of conservative tracers to mixing‐controlled degradation of reactive compounds.
Proof of Concept: Pharmacological Preconditioning with a Toll-like Receptor Agonist Protects against Cerebrovascular Injury in a Primate Model of Stroke
Authors: Bahjat Frances Rena , Williams-Karnesky Rebecca L , Kohama Steven G , West G Alexander , Doyle Kristian P , Spector Maxwell D , Hobbs Theodore R , Stenzel-Poore Mary P
Published: February 2011

Cerebral ischemic injury is a significant portion of the burden of disease in developed countries; rates of mortality are high and the costs associated with morbidity are enormous. Recent therapeutic approaches have aimed at mitigating the extent of damage and/or promoting repair once injury has occurred. Often, patients at high risk of ischemic injury can be identified in advance and targeted for antecedent neuroprotective therapy. Agents that stimulate the innate pattern recognition receptor, Toll-like receptor 9, have been shown to induce tolerance (precondition) to ischemic brain injury in a mouse model of stroke. Here, we demonstrate for the first time that pharmacological preconditioning against cerebrovascular ischemic injury is also possible in a nonhuman primate model of stroke in the rhesus macaque. The model of stroke used is a minimally invasive transient vascular occlusion, resulting in brain damage that is primarily localized to the cortex and as such, represents a model with substantial clinical relevance. Finally, K-type (also referred to as B-type) cytosine-guanine-rich DNA oligonucleotides, the class of agents employed in this study, are currently in use in human clinical trials, underscoring the feasibility of this treatment in patients at risk of cerebral ischemia.
Production and Maternal Report of 16- and 18-Month-Olds' Vocabulary in Low- and Middle-Income Families
Authors: Furey Joan E.
Published: February 2011

Purpose

To compare maternal report of children’s vocabularies on the MacArthur Communicative Development Inventories Words and Gestures form (CDI:WG; Fenson et al., 1993) with spontaneous production data in both low- and middle-income families.

Method

As part of a longitudinal investigation, language samples were gathered from 23 mother–child dyads based on Stoel-Gammon’s (1987) protocol for the Language Production Scale when the children were 16 and 18 months of age. The mothers also completed the CDI:WG at both visits. The words that the children produced were compared with those the mothers reported on the vocabulary checklist, with family income and vocabulary size as grouping factors.

Results

Maternal reporting did not differ as a function of socioeconomic status but did increase from 16 to 18 months.

Conclusions

The vocabulary differences observed on the CDI:WG for children from low-income families do not appear to be a reflection of inaccurate maternal reporting. Further research is needed to determine whether these findings will generalize more broadly.
Identification of Adults With Developmental Language Impairments
Authors: Fidler Lesley J. , Plante Elena , Vance Rebecca
Published: February 2011

Purpose

To assess the utility of a wide range of language measures (phonology, morphology, syntax, and semantics) for the identification of adults with developmental language impairment.

Method

Measures were administered to 3 groups of adults, each representing a population expected to demonstrate high levels of language impairment, and to matched control groups.

Results

Three measures were the strongest contributors to identification of language impairment in the 3 groups of adults. These measures, combined, maximized identification of members of the clinical groups as having impaired language (sensitivity) and members of the control groups as having typical language (specificity).

Conclusion

This suggests that a relatively brief battery could have utility for identifying developmental language impairment during the adult years.
Photoemission study of praseodymia in its highest oxidation state: The necessity of in situ plasma treatment
Authors: Schaefer A. , Gevers S. , Zielasek V. , Schroeder T. , Falta J. , Wollschläger J. , Bäumer M.
Published: February 2011

A cold radio frequency oxygen plasma treatment is demonstrated as a successful route to prepare clean, well-ordered, and stoichiometric PrO2 layers on silicon. High structural quality of these layers is shown by x-ray diffraction. So far unobserved spectral characteristics in Pr 3d x-ray photoelectron (XP) spectra of PrO2 are presented as a fingerprint for praseodymia in its highest oxidized state. They provide insight in the electronic ground state and the special role of praseodymia among the rare earth oxides. They also reveal that former XP studies suffered from a significant reduction at the surface.
Implementation of the analytic energy gradient for the combined time-dependent density functional theory/effective fragment potential method: Application to excited-state molecular dynamics simulations
Authors: Minezawa Noriyuki , De Silva Nuwan , Zahariev Federico , Gordon Mark S.
Published: February 2011

Excited-state quantum mechanics/molecular mechanics molecular dynamics simulations are performed, to examine the solvent effects on the fluorescence spectra of aqueous formaldehyde. For that purpose, the analytical energy gradient has been derived and implemented for the linear-response time-dependent density functional theory (TDDFT) combined with the effective fragment potential (EFP) method. The EFP method is an efficient ab initio based polarizable model that describes the explicit solvent effects on electronic excitations, in the present work within a hybrid TDDFT/EFP scheme. The new method is applied to the excited-state MD of aqueous formaldehyde in the n-π* state. The calculated π*→n transition energy and solvatochromic shift are in good agreement with other theoretical results.
Dehydrogenation of defects and hot-electron degradation in GaN high-electron-mobility transistors
Authors: Puzyrev Y. S. , Roy T. , Beck M. , Tuttle B. R. , Schrimpf R. D. , Fleetwood D. M. , Pantelides S. T.
Published: February 2011

Degradation mechanisms limiting the electrical reliability of GaN high-electron-mobility transistors (HEMTs) are generally attributed to defect generation by hot-electrons but specific mechanisms for such processes have not been identified. Here we give a model for the generation of active defects by the release of hydrogen atoms that passivate pre-exisiting defects. We report first-principles density-functional calculations of several candidate point defects and their interaction with hydrogen in GaN, under different growth conditions. Candidate precursor point defects in device quality GaN are identified by correlating previously observed trap levels with calculated optical levels. We propose dehydrogenation of point defects as a generic physical mechanism for defect generation in HEMTs under hot-electron stress when the degradation is not spontaneously reversible. Dehydrogenation of point defects explains (1) observed hot electron stress transconductance degradation, (2) increase in yellow luminescence, and opposite threshold voltage shifts in devices where the material was grown under nitrogen- and ammonia-rich conditions.
Characterizing the effects of etch-induced material modification on the crystallization properties of nitrogen doped Ge2Sb2Te5
Authors: Washington J. S. , Joseph E. A. , Raoux S. , Jordan-Sweet J. L. , Miller D. , Cheng H.-Y. , Schrott A. G. , Chen C.-F. , Dasaka R. , Shelby B. , Lucovsky G. , Paesler M. A. , Miotti L. , Lung H.-L. , Zhang Y. , Lam C. H.
Published: February 2011

The chemical and structural effects of processing on the crystallization of nitrogen doped Ge2Sb2Te5 is examined via x-ray photoelectron spectroscopy (XPS), x-ray absorption spectroscopy (XAS), time resolved laser reflectivity, and time resolved x-ray diffraction (XRD). Time resolved laser reflectivity and XRD show that exposure to various etch and ash chemistries significantly reduces the crystallization speed while the transition temperature from the rocksalt to the hexagonal phase is increased. XPS and XAS attribute this to the selective removal and oxidization of N, Ge, Sb, and Te, thus altering the local bonding environment to the detriment of device performance.
Dynamics of hard sphere suspensions using dynamic light scattering and X-ray photon correlation spectroscopy: Dynamics and scaling of the intermediate scattering function
Authors: Martinez V. A. , Thijssen J. H. J. , Zontone F. , van Megen W. , Bryant G.
Published: February 2011

Intermediate scattering functions are measured for colloidal hard sphere systems using both dynamic light scattering and x-ray photon correlation spectroscopy. We compare the techniques, and discuss the advantages and disadvantages of each. Both techniques agree in the overlapping range of scattering vectors. We investigate the scaling behavior found by Segré and Pusey [Phys. Rev. Lett. 77, 771 (1996)] but challenged by Lurio et al. [Phys. Rev. Lett. 84, 785 (2000)]. We observe a scaling behavior over several decades in time but not in the long-time regime. Moreover, we do not observe long-time diffusive regimes at scattering vectors away from the peak of the structure factor and so question the existence of long-time diffusion coefficients at these scattering vectors.
Density functional theory study of Fe3Ga
Authors: Paduani C. , Bormio-Nunes C.
Published: February 2011

First-principles scalar relativistic calculations in supercells of 16 atoms are used to represent disordered B2 ordering of Fe3Ga in order to observe the effect of Ga–Ga pairs on the electronic structure of this alloy. From a comparison with pure bcc Fe it is observed that the energy position and occupation of eg and t2g states are largely affected by the Ga–Ga pairs and strengthened intraplane interactions takes place. The results show that a larger hybridization of the conduction band is in the source of the magnetostriction enhancement experimentally observed in Galfenol.
A constant-speed lowering mechanism for the crucibles
Authors: Bangaru S. , Muralidharan G.
Published: February 2011

The crystal growth characteristics of a certain material can be considerably influenced by the strain present in the growing crystal. Strain can be induced in various ways. One of the most common methods always presents in industrial processes, where attrition processes are always accompanied by generation of mechanical strain in a newly formed small crystal fragment obtained by mechanical stressing during preparation and handling. For this purpose, we have developed an apparatus which comprises a specially designed constant, special lowering device. The system was constructed for use with a Bridgeman furnace made in the laboratory for the crystal growth. The apparatus has been used with a variety of growth assemblies to grow crystals of materials with melting points in the range of 100–1000°C.
First-principles calculations of electronic, optical, and thermodynamic properties of SrSi2
Authors: Chen Z. J. , Tian D. B.
Published: February 2011

The electronic, optical, and thermodynamics properties for SrSi2 crystals have been investigated by using the first-principles total energy calculations. The electronic structures of SrSi2 show that the top of the valence band is determined by Si 3p states, the bottom of the conduction band is determined by Sr 3d states, and the band structure presents an indirect narrow-gap semiconductor character with energy gap of 0.0618 eV. Finally, the optical and thermodynamic properties are obtained and discussed in detail for the first report.
Numerical analysis of packetlike charge behavior in low-density polyethylene by a Gunn effectlike model
Authors: Xia Junfeng , Zhang Yewen , Zheng Feihu , An Zhenlian , Lei Qingquan
Published: February 2011

Under some conditions, charges may transport like an isolated packet in polyethylene. It has been demonstrated that many factors, such as applied field strength, temperature, and material itself, influence on formation and migration of space charge packet, which cause many difficulties in understanding the general mechanism of the phenomenon. In this paper, based on the analysis about the influences of charge injection, carriers’ migration, and the interaction between the free charge and trap in polyethylene on packetlike space charge behavior, a new physical model is established to give a physical description of packetlike charge behavior in low density polyethylene (LDPE). This model includes some interesting features: (1) it gives an exact calculation of charge changes in all positions of specimens; (2) the negative differential mobility mechanism of Gunn effect in semiconductor is introduced to explain the generating process of space charge packet; (3) field-induced charge detrapping model is utilized to simulate the diversity of packetlike charge packet behavior under different applied fields. By considering such a model, we simulate two kinds of positive packetlike charge behavior in LDPE from different research groups. The simulated results show well fitting with the experiment data.
Ultrafast spectroscopy and coherent acoustic phonons of Au–Ag core–shell nanorods
Authors: Wang Li , Kiya Ayaka , Okuno Yoshifumi , Niidome Yasuro , Tamai Naoto
Published: February 2011

We performed the first investigations of coherent acoustic phonons in Au–Ag core–shell nanorods, which were compared with the results of parental Au nanorods. Both breathing and extensional modes were observed in Au–Ag core–shell nanorods with ∼11 nm Ag shell while only extensional modes were detected in other core–shell nanorods with 4–7 nm Ag shell. Young's modulus estimated from the oscillation period of extensional modes was found to be larger for Au–Ag core–shell nanorods with ∼4 nm Ag shell, as compared with that of Au nanorods. The value of Young's modulus decreases with the increase of the Ag shell thickness and finally becomes smaller than that of Au nanorods. This phenomenon is interpreted in terms of the surface effects and the existence of grain boundaries in the lattice structure of Ag shell.
Electronic structure of three-dimensional isotropic quantum dots by four-component relativistic coupled cluster methods
Authors: Yakobi Hana , Eliav Ephraim , Kaldor Uzi
Published: February 2011

Quantum dots with three-dimensional isotropic harmonic confining potentials and up to 60 electrons are studied. The Dirac–Coulomb Hamiltonian serves as a framework, so that relativistic effects are included, and electron correlation is treated at a high level by the Fock-space coupled cluster method, with single and double excitations summed to all orders. Large basis sets composed of spherical Gaussian functions are used. Energies of ground and excited states are calculated. The orbital order is 1s, 2p, 3d, 3s, 4f, 4p, 5g, … , and closed-shell structures appear for 2, 8, 18, 20, 34, 40, and 58 electrons. Relativistic effects are negligible for low strengths of the harmonic potential and increase rapidly for stronger potentials. Breit contributions, coming from the lowest order relativistic correction to the interelectronic repulsion terms, are also studied. Correlation effects are significant for these systems, in particular for weak confining potentials and for small systems, where they constitute up to 6% of the total energies. Their relative weight goes down (although they increase in absolute value) for larger systems or confining potentials. Planned applications to quantum dots with impurities are discussed briefly.
Experimental and computational study of crystalline formic acid composed of the higher-energy conformer
Authors: Hakala Mikko , Marushkevich Kseniya , Khriachtchev Leonid , Hämäläinen Keijo , Räsänen Markku
Published: February 2011

Crystalline formic acid (FA) is studied experimentally and by first-principles simulations in order to identify a bulk solid structure composed of the higher-energy (cis) conformer. In the experiments, deuterated FA (HCOOD) was deposited in a Ne matrix and transformed to the cis conformer by vibrational excitation of the ground state (trans) form. Evaporation of the Ne host above 13 K prepared FA in a bulk solid state mainly composed of cis-FA. Infrared absorption spectroscopy at 4.3 K shows that the obtained solid differs from that composed of trans-FA molecules and that the state persists up to the annealing temperature of at least 110 K. The first-principles simulations reveal various energetically stable periodic chain structures containing cis-FA conformers. These chain structures contain either purely cis or both cis and trans forms. The vibrational frequencies of the calculated structures were compared to the experiment and a tentative assignment is given for a novel solid composed of cis-FA.
Electric deflection of rotating molecules
Authors: Gershnabel E. , Averbukh I. Sh.
Published: February 2011

We provide a theory of the deflection of polar and nonpolar rotating molecules by inhomogeneous static electric field. Rainbowlike features in the angular distribution of the scattered molecules are analyzed in detail. Furthermore, we demonstrate that one may efficiently control the deflection process with the help of short and strong femtosecond laser pulses. In particular, the deflection process may be turned off by a proper excitation, and the angular dispersion of the deflected molecules can be substantially reduced. We study the problem both classically and quantum mechanically, taking into account the effects of strong deflecting field on the molecular rotations. In both treatments we arrive at the same conclusions. The suggested control scheme paves the way for many applications involving molecular focusing, guiding, and trapping by inhomogeneous fields.