cssi/SciSciGPT-SciSciNet huggingface dataset:
Characterization of 4H Semi-Insulating Silicon Carbide Single Crystals Using Electron Beam Induced Current

Abstract In this work we demonstrate the electron beam induced current (EBIC) contrast of dislocations in semi-insulating (SI) bulk SiC single crystals. Our investigations revealed that the screw dislocations produce dark EBIC contrast indicating high leakage current in the defective regions. This type of screw dislocations are harmful for high resolution radiation detectors and should be eliminated by improving the crystal qualities. Chemical etching in molten KOH was used for dislocation mapping in the test structures and to correlate EBIC contrast with dislocations. The EBIC contrast found in our study in SI SiC is discussed.
Leptin levels reflect body lipid content in mice: Evidence for diet-induced resistance to leptin action

The regulation of body weight and composition involves input from genes and the environment, demonstrated, for example, by the variable susceptibility of inbred strains of mice to obesity when offered a high-fat diet. The identification of the gene responsible for obesity in the ob/ob mouse provides a new approach to defining links between diet and genetics in the regulation of body weight. The ob gene protein product, leptin, is an adipocyte-derived circulating protein. Administration of recombinant leptin reduces food intake and increases energy expenditure in ob/ob mice, suggesting that it signals to the brain the magnitude of fat stores. Information on the regulation of this protein is limited. In several rodent models of obesity including db/db, fa/fa, yellow (Ay/a) VMH-lesioned, and those induced by gold thioglucose, monosodium glutamate, and transgenic ablation of brown adipose tissue, leptin mRNA expression and the level of circulating leptin are increased, suggesting resistance to one or more of its actions. We have assessed the impact of increased dietary fat on circulating leptin levels in normal FVB mice and FVB mice with transgene-induced ablation of brown adipose tissue. We find that high-fat diet evokes a sustained increase in circulating leptin in both normal and transgenic mice, with leptin levels accurately reflecting the amount of body lipid across a broad range of body fat. However, despite increased leptin levels, animals fed a high-fat diet became obese without decreasing their caloric intake, suggesting that a high content of dietary fat changes the 'set point' for body weight, at least in part by limiting the action of leptin.
Length polymorphism at the avpr1a locus is correlated with male reproductive behavior in a natural population of prairie voles ( Microtus ochrogaster )

Laboratory studies have shown that vasopressin can influence sociosexual behavior through its action on the vasopressin 1a receptor (V1aR). There is substantial evidence that the length of a microsatellite in the gene (avpr1a) encoding for the V1aR can affect social attachment to females and paternal behavior in male prairie voles under laboratory conditions. However, previous field studies of prairie voles have failed to detect a strong effect of the length of a male’s avpr1a allele on their sociosexual behavior, but these studies are typically much shorter than the average prairie vole breeding lifespan. We examined the relationship between male avpr1a microsatellite allele length and sociosexual behavior in a natural population of prairie voles for 15 weeks, closer to the lifespan of prairie voles in nature. Contrary to predictions, we found that males with the longest avpr1a microsatellite alleles were significantly more likely to sire offspring with more than one female and to sire offspring that survived until trappable age than males with the shortest avpr1a microsatellite allele lengths. This relationship was the strongest for males with the longest tenure on the study site. As in previous field studies, we did not find evidence of a relationship between a male’s avpr1a genotype and any index of social behavior including male residency status or the number of females with which males associate. This is the first study to support the hypothesis that a male’s avpr1a genotype is a factor underlying variation in the genetic mating system of prairie voles under natural conditions.
Labeling reactions applicable to chromatography and electrophoresis of minute amounts of proteins

Chromatography and electrophoresis have become extremely valuable and important methods for the separation, purification, detection and analysis of biopolymers and HPLC/HPCE may become the premier, preferable approaches for both qualitative and quantitative analyses of most proteins, especially from recombinant materials. This includes smaller peptides, polypeptides, proteins, antibodies and all types of protein or antibody-conjugates (antibody-enzyme, protein-fluorescent probe, antibody-drug and so forth). This entire Topical Issue of Journal of Chromatography emphasizes the application of chromatography and electrophoresis to protein analysis. This particular review deals with approaches to the selective tagging or labeling of proteins at trace (minute) levels, again using either chromatography or electrophoresis, with the emphasis on modern HPLC/HPCE methods and approaches. We discuss here both pre- and post-column labeling methods and reagents, techniques for realizing selective labeling of proteins or antibodies, applicable approaches to protein preconcentration in both HPLC and HPCE areas and in general, methods for improving (lowering) detection limits for proteins utilizing chemical or physical derivatization and/or preconcentration techniques. There are really two major goals or emphases in that which follows: (1) methods for selective labeling of proteins prior to or after HPLC/HPCE and (2) labeling of proteins at trace levels for improved separation-detection and lowered detection limits. We discuss here a large number of specific references related to both pre- and post-column/capillary derivatizations for proteins, as well as methods for improved detectability in both HPLC and HPCE by, for example, analyte preconcentration on a solid-phase extractor or membrane support, capillary isotachophoresis and other methods. Selective reactions or derivatizations on proteins refers to the ability to tag the protein at specific (e.g. reactive amino sites) in a controlled manner, with the products having the same number of tags all at the very same site or sites. The products are all the same species, having the same number of tags at the same locations on the protein. Selective reactions can also refer to the idea of tagging all of the protein sample at only a single, same site or at all available sites, homogeneously.
Latent thermally activated interface-trap generation in MOS devices

A large increase in interface-trap density (up to a factor of five) has been observed in commercial MOS devices at very long times after irradiation (>10/sup 6/ s). This latent buildup occurs after an initial apparent saturation of interface-trap density, which occurs typically within approximately 10/sup 2/-10/sup 4/ s after irradiation. The latent buildup is thermally activated. with an activation energy of approximately 0.47 ev. Within experimental uncertainty, this is equal to the activation energy ( approximately 0.45 eV) for the diffusion of molecular hydrogen in bulk fused silica. Latent interface-trap buildup can degrade the performance of devices in low-dose-rate radiation environments (e.g. space). >
Age-related slowing of myosin actin cross-bridge kinetics is sex specific and predicts decrements in whole skeletal muscle performance in humans.

We hypothesize that age-related skeletal muscle dysfunction and physical disability may be partially explained by alterations in the function of the myosin molecule. To test this hypothesis, skeletal muscle function at the whole muscle, single fiber, and molecular levels was measured in young (21–35 yr) and older (65–75 yr) male and female volunteers with similar physical activity levels. After adjusting for muscle size, older adults had similar knee extensor isometric torque values compared with young, but had lower isokinetic power, most notably in women. At the single-fiber and molecular levels, aging was associated with increased isometric tension, slowed myosin actin cross-bridge kinetics (longer myosin attachment times and reduced rates of myosin force production), greater myofilament lattice stiffness, and reduced phosphorylation of the fast myosin regulatory light chain; however, the age effect was driven primarily by women (i.e., age-by-sex interaction effects). In myosin heavy chain IIA fibers, single-fiber isometric tension and molecular level mechanical and kinetic indexes were correlated with whole muscle isokinetic power output. Collectively, considering that contractile dysfunction scales up through various anatomical levels, our results suggest a potential sex-specific molecular mechanism, reduced cross-bridge kinetics, contributes to the reduced physical capacity with aging in women. Thus these results support our hypothesis that age-related alterations in the myosin molecule contribute to skeletal muscle dysfunction and physical disability and indicate that this effect is stronger in women.
syngva: an object that raises questions of agency, relationship, and control

The division between subject and object, agent and non-agent, has consistently been dubious philosophically. Now we are increasingly faced with computational objects and relational artifacts that put into question cherished notions of human agency and intentionality. I describe one such object, syngva, a creature that develops through evolutionary processes idiosyncratic movements in response to non-speech vocalizations. syngva serves two parallel roles. For the user, syngva enables a form of non-linguistic expression, serving as a catalyst for novel vocal behaviors provoked by the motions of the object. For myself, syngva acts as a sociological probe, allowing me to study in-situ relationship formation, agency, and control in response to an "intelligent" creature. I describe an evaluation approach that draws heavily from actor-network theory (ANT), a methodology that in part places objects on the same ontological level as human agents. This re-centering of agency intimates a different way of looking at the person-object dyad that focuses on the interactions themselves without reference to pre-existing theories.
The Lived Experience of Socialization Among African American Nursing Students in a Predominantly White University

Purpose: This study explored the phenomenon of socialization among African American nursing students in predominantly White universities. Recruitment and retention of African American nursing students is in lower percentages compared with other groups. Many nursing schools reflect a culture of the White middle class, which may present a barrier to minority students by requiring students to socialize to a culture different from their own. Overcoming such barriers cannot begin until the experience of socialization is understood. Design: A sample consisting of eight co-researchers was used who all attended nursing school at a predominantly White university. Interviews were analyzed using Colaizzi’s phenomenological method. Results: The following six themes emerged: Theme 1—The Strength to Pursue More, Theme 2—Encounters With Discrimination, Theme 3—Pressure to Succeed, Theme 4—Isolation and Sticking Together, Theme 5—To Fit In and Talk White, and Theme 6—To Learn With New Friends and Old Ones. Conclusions: T...
Children and Marital Happiness Why the Negative Correlation

This study examines the causal processes that lead to the widely observed negative association between presence of children and marital happiness. Using a nationwide panel of 1535 married individuals, we find support for two primary causal mechanisms. First, the presence of children is associated with differences in marital structure (lower interaction, more dissatisfaction with finances and the division of labor, and more traditionalism of the division of labor) that are, in turn, associated with lower marital happiness. We also find, however, that the relationship between marital happiness and children is partially spurious. The presence of preschoolers and especially the birth of a first child serve to reduce the likelihood that unhappily married people will divorce within a three-year period. As a result, a larger proportion of unhappily married people is retained temporarily in the parent population and thus contributes to the observed negative relation between presence of children and marital happiness.
Leveraging hierarchy in medical codes for predictive modeling

ICD-9 codes are among the most important patient information recorded in electronic health records. They have been shown to be useful for predictive modeling of different adverse outcomes in patients, including diabetes and heart failure. An important characteristic of ICD-9 codes is the hierarchical relationships among different codes. Nevertheless, the most common feature representation used to incorporate ICD-9 codes in predictive models disregards the structural relationships.In this paper, we explore different methods to leverage the hierarchical structure in ICD-9 codes with the goal of improving performance of predictive models. We compare methods that leverage hierarchy by 1) incorporating the information during feature construction, 2) using a learning algorithm that addresses the structure in the ICD-9 codes when building a model, or 3) doing both. We propose and evaluate a novel feature engineering approach to leverage hierarchy, while simultaneously reducing feature dimensionality.Our experiments indicate that significant improvement in predictive performance can be achieved by properly exploiting ICD-9 hierarchy. Using two clinical tasks: predicting chronic kidney disease progression (Task-CKD), and predicting incident heart failure (Task-HF), we show that methods that use hierarchy outperform the conventional approach in F-score (0.44 vs 0.36 for Task-HF and 0.40 vs 0.37 for Task-CKD) and relative risk (4.6 vs 3.3 for Task-HF and 5.9 vs 3.8 for Task-CKD).
Undocumented Immigrants and Access to Health Care: Making a Case for Policy Reform:

The growth in undocumented immigration in the United States has garnered increasing interest in the arenas of immigration and health care policy reform. Undocumented immigrants are restricted from accessing public health and social service as a result of their immigration status. The Patient Protection and Affordability Care Act restricts undocumented immigrants from participating in state exchange insurance market places, further limiting them from accessing equitable health care services. This commentary calls for comprehensive policy reform that expands access to health care for undocumented immigrants based on an analysis of immigrant health policies and their impact on health care expenditures, public health, and the role of health care providers. The intersectional nature of immigration and health care policy emphasizes the need for nurse policymakers to advocate for comprehensive policy reform aimed at improving the health and well-being of immigrants and the nation as a whole.
Effects of Immobilization on the Biomechanical Properties of the Broiler Tibia and Gastrocnemius Tendon

Researchers have provided much insight into the various factors that influence the incidence of musculoskeletal problems in the poultry industry. However, a better understanding of the mechanobiology of broiler bone and tendon can have a positive effect on the welfare of the production bird and assist in the development of improved production practices. This study investigated the mechanical adaptability responses due to disuse on the biomechanical properties of the broiler tibia and gastrocnemius tendon. Beginning at 3 wk of age, broilers were placed in a harness system designed to eliminate load bearing of the leg. After 2 wk of this treatment, the average values for body mass and shank length of the birds were 58 and 85% of the values for the controls, respectively. The treatment reduced the mineral content of the tibia by approximately 50%, tibia structural strength by 40%, and tibia material strength by 8%. The structural strength and toughness of the gastrocnemius tendon were reduced by 10 and 30%, respectively, whereas the material strength, material toughness, and material stiffness of the tendon increased by approximately 75, 65, and 70%, respectively.
Drag reduction in wall-bounded turbulence via a transverse travelling wave

Computational experiments based on direct numerical simulation of wall-bounded flow reveal that turbulence production can be suppressed by the action of a transverse travelling wave. Flow visualizations show that the near-wall flow structure is altered substantially, compared to other turbulence control techniques, leading to a large amount of shear stress reduction (i.e., more than 30%). The travelling wave can be induced by a spanwise force that is confined within the viscous sublayer, it has its maximum at the wall, and decays exponentially away from it. We demonstrate the robustness of this approach, and its application in salt water using arrays of electro-magnetic tiles that can produce the required travelling wave excitation. We also study corresponding results from spanwise oscillations using a similar force, which also leads to large drag reduction. Although the turbulence statistics for the two approaches are similar, the near-wall structures appear to be different: in the spanwise oscillatory excitation there is a clear presence of wall-streaks whereas in the travelling wave excitation these streaks have disappeared. From the fundamental point of view, the new finding of this work is that appropriate enhancement of the streamwise vortices leads to weakening of the streak intensity, as measured by the normal vorticity component, and correspondingly substantial suppression of turbulence production. From the practical point of view, our findings provide guidance for designing different surface-based actuation techniques including piezoelectric materials, shape memory alloys, and electro-magnetic tiles.
Rescaling reliability bounds for a new operational profile

One of the main problems with reliability testing and prediction is that the result is specific to a particular operational profile. This paper extends an earlier reliability theory for computing a worst case reliability bound. The extended theory derives a re-scaled reliability bound based on the change in execution rates of the code segments in the program. In some cases it is possible to derive a maximum failure rate bound that applies to any change in the profile. It also predicts that (in principle) a "fair" test profile can be derived where the reliability bounds are relatively insensitive to the operational profile. In addition the theory allows unit and module test coverage measures to be incorporated into an operational reliability bound prediction. The implications of the theory are discussed, and the theory is evaluated by applying it to two example programs with known faults.
Relationship between immune and behavioral measures in schizophrenia

Schizophrenia, which is a chronic but episodic disorder of unknown etiology, shares immunological features with organ specific autoimmune diseases such as multiple sclerosis (MS), rheumatoid arthritis and insulin-dependent diabetes mellitus. However, recent studies have raised the issue as to whether the reported immune disturbances in schizophrenia may be the result of a stress-induced dysregulation of CNS cytokine production, rather than a permanent immunological disorder, i.e., autoimmunity.
Progress: the ROPAC multinational registry advances our understanding of an important outcome in pregnant women with heart disease.

When caring for women with structural heart disease (SHD), clinicians face an apparent paradox: most women with SHD are able to complete a pregnancy without complication; however, compared with the general population, maternal risk is increased and SHD remains a major source of maternal morbidity and mortality and poor fetal outcomes.1–4 Identifying those women with SHD who are at increased risk for meaningful complications during pregnancy is critical. During pregnancy, intravascular volume, stroke volume, heart rate and cardiac output increase, while systemic vascular resistance decreases. During pregnancy, women with congenital heart disease (CHD), cardiomyopathy or valve disease can develop heart failure due to these physiologic changes. Preconception risk stratification allows women with heart disease to decide if they wish to conceive. Additionally, identifying patients at high risk for cardiac complications provides time to plan the optimal strategy for cardiac surveillance and management during pregnancy. Various models have been developed in order to determine which cardiac conditions place women at highest risk for cardiac complications during pregnancy (table 1). View this table: Table 1 Demographics and rates of heart failure in previous large studies of women with structural heart disease The European Society of Cardiology's Registry on Pregnancy and Cardiac disease (ROPAC) collected information on 1321 pregnancies of women with structural and ischaemic heart disease in 28 countries. Investigators followed women though pregnancy and reported on maternal and fetal complications.5 Ruys et al 6 present the heart failure data from ROPAC. Importantly, the authors report heart failure as a stand-alone end point. This has advantages compared with other studies that report composite end points (death, heart failure, arrhythmia, myocardial infarction and cerebrovascular accidents).1–3 Although composite end points are useful in allowing smaller study size, limitations exist unless each component …
Dynamic transient fault detection and recovery for embedded processor datapaths

As microprocessors continue to evolve and grow in functionality, the use of smaller nanometer technology scaling coupled with high clock frequencies and exponentially increasing transistor counts dramatically increases the susceptibility of transient faults. However, the correct and reliable operation of these processors is often compulsory, both in terms of consumer experience and for high-risk embedded domains such as medical and transportation systems. Thus, economical fault detection and recovery becomes essential to meet all necessary market requirements. This paper explores the efficient leveraging of superscalar, out-of-order architectures to enable multi-cycle transient fault-tolerance throughout the datapath in a novel manner. By using dynamic instruction execution redundancy, soft errors within the datapath are both detected and recovered. The proposed microarchitecture selectively reevaluates corrupted instructions, reducing the recovery impact by preserving completed instructions unaffected by the fault. The additional computational workload is dynamically staggered to leverage the out-of-order nature of the architecture and minimize resource conflicts and delays.
Efficacy of interventions with caregivers: a reanalysis

This paper presents a reanalysis of data from a previously reported study with family caregivers of dementia patients using the method of prediction analysis. Compared with subjects on a waiting list or enrolled in support groups, caregivers in individual and family counseling were more likely to have successful outcomes on all dependent measures (Brief Symptom Inventory, personal strain, and role strain).
Handbook of Copper Toxicology. Edward J. Massaro, ed. Totowa, NJ: Humana Press, 2002, 624 pp., $175.00. ISBN 0-86903-943-9.

This is an extremely informative and timely text that summarizes the current research in the rapidly expanding area of copper metabolism and toxicology. The preface gives a concise overview in addition to introducing the importance of copper in biological systems and the disorders arising from the mishandling of copper. It is therefore extremely useful to those with only a cursory knowledge of copper metabolism. The book is divided into six sections: “Copper in Mammals”, “Copper Proteins”, “Copper Transport”, “Molecular Pathogenesis of Diseases of Copper Metabolism”, “Copper Toxicity and Therapeutics”, and “Copper Metabolism and Homeostasis”, followed by an …
A methodology for partitioning long local computer networks

The authors present a new methodology for partitioning long local computer networks. The proposed technique relies on dividing the long network into subnets that are interconnected using a multistage delta interconnection network and an interface device. The performance of the proposed partitioning method is studied using simulation modeling. It is found that the throughput of the proposed partitioned network is improved and the average packet delay is reduced as compared to the single long network. >
The relationship of slide maturity and trypsin exposure time in the differential Giemsa banding of chromosomes.

Difficulty has been reported in attaining consistent chromosome banding using trypsin-Giemsa techniques. When trypsin concentration, incubation temperature, and the duration of staining are held constant, a logarithmic relationship has been found to exist between the length of time since a slide was made and the length of trypsin treatment necessary to produce optimal banding when it is stained. Under the conditions specified in this report, ten seconds digestion was optimal for ten-day-old slides. This time approximately doubled for each additional eight days that slides were allowed to age. From a plot of the experimental results, treatment times appropriate for slides of any age from 10 to 60 days were obtained. Use of these times produced satisfactory banding in 85% of mitoses.
Optimising Learning Using Flashcards: Spacing Is More Effective Than Cramming

SUMMARY The spacing effect—that is, the benefit of spacing learning events apart rather than massing them together—has been demonstrated in hundreds of experiments, but is not well known to educators or learners. I investigated the spacing effect in the realistic context of flashcard use. Learners often divide flashcards into relatively small stacks, but compared to a large stack, small stacks decrease the spacing between study trials. In three experiments, participants used a web-based study programme to learn GRE-type word pairs. Studying one large stack of flashcards (i.e. spacing) was more effective than studying four smaller stacks of flashcards separately (i.e. massing). Spacing was also more effective than cramming—that is, massing study on the last day before the test. Across experiments, spacing was more effective than massing for 90% of the participants, yet after the first study session, 72% of the participants believed that massing had been more effective than spacing. Copyright # 2009 John Wiley & Sons, Ltd.
Frequency, clinical presentation, and outcomes of drug-induced liver injury after liver transplantation

Drug-induced liver injury (DILI) is increasingly being recognized as a common cause of acute hepatitis. The clinical impact of DILI after liver transplantation (LT) is not known. The aim of this study was to describe the frequency, clinical presentation, and outcomes of DILI in LT recipients. LT recipients with possible DILI were identified with electronic pathology records and clinical note database retrieval tools. Diagnostic criteria were applied to identify cases of DILI. Twenty-nine of 1689 LT recipients (1.7%) were identified with DILI. The mean age was 52 years, and 52% were women. The major indications for LT were primary sclerosing cholangitis (28%), cholangiocarcinoma (14%), and hepatocellular carcinoma (14%). The severity of DILI was mild or moderate in 92% of the cases. Nausea or diarrhea (31%), jaundice (24%), and pruritus (10%) were the most common symptoms at the time of diagnosis. The mean biochemistry values were as follows: alanine aminotransferase, 204 ± 263 U/L; aspartate aminotransferase, 108 ± 237 U/L; alkaline phosphatase, 469 ± 689 U/L; and total bilirubin, 1.9 ± 10.3 mg/dL. The median duration of medication use until the diagnosis of DILI was 57 days, and the major agent classes were antibiotics (48%), immunosuppressive agents (14%), and antihyperlipidemic drugs (7%). Trimethoprim-sulfamethoxazole was the most common implicated agent (n = 11). Serum liver enzymes improved within a median time of 34 days (range = 5-246 days) after drug withdrawal. Hepatic retransplantation or death did not occur. Among the 50 cases with possible DILI explained by other causes, 13 individuals (26%) had no alternative diagnosis despite histological findings compatible with DILI. In conclusion, DILI is a rare yet underrecognized event among LT recipients. The majority of cases are not clinically severe, and they resolve after drug cessation without hepatic retransplantation or death.
Altered expression of protein tyrosine phosphatase, non-receptor type 22 isoforms in systemic lupus erythematosus

Introduction A C-to-T single nucleotide polymorphism (SNP) located at position 1858 of human protein tyrosine phosphatase, non-receptor type 22 (PTPN22) complementary DNA (cDNA) is associated with an increased risk of systemic lupus erythematosus (SLE). How the overall activity of PTPN22 is regulated and how the expression of PTPN22 differs between healthy individuals and patients with lupus are poorly understood. Our objectives were to identify novel alternatively spliced forms of PTPN22 and to examine the expression of PTPN22 isoforms in healthy donors and patients with lupus.
Transcriptional Restriction of Human Immunodeficiency Virus Type 1 Gene Expression in Undifferentiated Primary Monocytes

Monocytes are critical precursors of dendritic cells and macrophages, which play an important role in the pathogenesis of human immunodeficiency virus type 1 (HIV-1). HIV-1 postentry infection is blocked in undifferentiated monocytes in vitro, while the underlying mechanisms are not fully understood. HIV-1 Tat-mediated transactivation of the viral long terminal repeat (LTR) promoter is essential for HIV-1 transcription. Two critical cellular cofactors of HIV-1 Tat, cyclin T1 (CycT1) and cyclin-dependent kinase 9 (CDK9), are required for LTR-directed HIV-1 transcription. In addition to the previously identified restrictions in early viral life cycle, we find that HIV-1 gene expression is impaired in undifferentiated primary monocytes. Transfection of monocytes by nucleofection with HIV-1 proviral DNA could not produce infectious HIV-1. The lack of Tat transactivation of the LTR promoter correlated with the impaired HIV-1 gene expression in monocytes. Interestingly, heterokaryons between primary monocytes and a human embryonic kidney cell line restored Tat transactivation of LTR, suggesting that monocytes lack cellular factors required for Tat transactivation. CycT1 protein was undetectable in freshly isolated monocytes and induced in monocyte-differentiated macrophages, while the expression of CDK9 remained constant. Transient expression of CycT1 in undifferentiated monocytes could not rescue Tat transactivation, suggesting that CycT1 is not the only limiting factor of HIV-1 infection in monocytes. Furthermore, monocyte differentiation into macrophages appeared to enhance the phosphorylation of CDK9, which correlated with significantly increased HIV-1 infection in macrophages. Our results provide new insights into HIV-1 infection and regulation in primary monocytes and viral pathogenesis.
Convective Delivery of Electroactive Species to Annular Nanoband Electrodes Embedded in Nanocapillary-Array Membranes

Significant technological drivers motivate interest in the use of reaction sites embedded within nanometer-scale channels, and an important class of these structures is realized by an embedded annular nanoband electrode (EANE) in a cylindrical nanochannel. In this structure, the convective delivery of electroactive species to the nanoelectrode is tightly coupled to the electrochemical overpotential via electroosmotic flow. Simulation results indicate that EANE arrays significantly outperform comparable microband electrode/microchannel structures, producing higher conversion efficiencies at low Peclet number. The results of this in-depth analysis are useful in assessing possible implementation of the EANE geometry for a wide range of electrochemical targets within microscale total analysis systems.
Behavioral responses to chemical stimulation of the olfactory organ in the squid Loligo opalescens

Behavioral experiments were carried out on restrained, but otherwise fully active, squid to test the chemoreceptive capabilities of the olfactory organ. Specific chemical substances stimulated high-pressure jet escape responses when ejected from a small pipette into the area immediately around the olfactory organ. These included squid ink and L-Dopa (3,4 dihydroxyphenylalanine) as well as agents that block voltage-dependent potassium channels, such as quaternary ammonium ions and 4-aminopyridine. Experiments designed to map chemosensitivity spatially identified the olfactory organ as the receptive site. Unilateral application of a topical local anesthetic to an olfactory organ selectively and reversibly abolished responsiveness on the treated side only. The olfactory organ can thus mediate detection of water-borne chemicals. This detection, in turn, is linked to motor control pathways involved in initiating escape-jetting behavior.
Revisiting Darwin's hypothesis: Does greater intraspecific variability increase species' ecological breadth?

 Premise of the study: Darwin fi rst proposed that species with larger ecological breadth have greater phenotypic variation. We tested this hypothesis by comparing intraspecifi c variation in specifi c leaf area (SLA) to species’ local elevational range and by assessing how external (abiotic) fi lters may infl uence observed differences in ecological breadth among species. Understanding the patterns of individual variation within and between populations will help evaluate differing hypotheses for structuring of communities and distribution of species.  Methods: We selected 21 species with varying elevational ranges and compared the coeffi cient of variation of SLA for each species against its local elevational range. We examined the infl uence of external fi lters on local trait composition by determining if intraspecifi c changes in SLA with elevation have the same direction and similar rates of change as the change in community mean SLA value.  Key results: In support of Darwin’s hypothesis, we found a positive relationship between species’ coeffi cient of variation for SLA with species’ local elevational range. Intraspecifi c changes in SLA had the same sign, but generally lower magnitude than the community mean SLA.  Conclusions: The results indicate that wide-ranging species are indeed characterized by greater intraspecifi c variation and that species’ phenotypes shift along environmental gradients in the same direction as the community phenotypes. However, across species, the rate of intraspecifi c trait change, refl ecting plastic and/or adaptive changes across populations, is limited and prevents species from adjusting to environmental gradients as quickly as interspecifi c changes resulting from community assembly.
The Costs and Benefits of Obliviousness: Growing Up in the 1950s

I was born in 1947, so I spent most of my childhood in the 1950s (and thus my adolescence in the 1960s) as a member of what is commonly referred to as the “Baby Boomer” generation. The name comes from the fact that after the relatively low birth rate associated with the Great Depression of the 1930s and the disruption of World War II (when more than eight million served in the military forces), with the end of the War and the return of the troops and prosperity, there was an explosion of births. From 1945 to 1946, the number of babies born in the USA jumped from 2.8 to 3.5 million per year and peaked in 1957 with a figure of 4.3 million [1]. It then held relatively steady for years to come as the siblings of the first wave of Baby Boomers were born and joined the swollen ranks of their older brothers and sisters (my younger brother was born in 1951 and my sister in 1958).
Inhibitory effects of cocaine on Ca2+ transients and contraction in single cardiomyocytes

The effects of cocaine on the Ca2+ transient responsible for excitation-contraction coupling were studied in single rat heart cells loaded with the fluorescent Ca2+ indicator fura 2. A high-speed imaging technique using a charge-coupled device as detector and transient image store [O'Rourke et al., Am. J. Physiol. 259 (Heart Circ. Physiol. 28): H230-H242, 1990] was used to measure cytosolic free Ca2+ concentration ([Ca2+]i) and contraction simultaneously from the images of fluorescence. Cardiomyocytes maintained a basal [Ca2+]i of approximately 140 nM in presence or absence of cocaine. After electrical field stimulation, [Ca2+]i increased to a peak of 498 +/- 25 nM under control conditions. This was reduced to a peak [Ca2+]i of 389 +/- 25 nM after treatment with 50 microM cocaine. Cocaine also reduced the rate of rise of [Ca2+]i but did not affect the time to peak or the half time for resequestration of the released Ca2+. The rate and extent of cell shortening was reduced by cocaine in parallel with the inhibition of the [Ca2+]i transient. Cocaine had no effect on the half time for relaxation. Cocaine did not modify the relationship between contraction and the elevation of [Ca2+]i over a range of extracellular Ca2+ concentrations. The intracellular pool of Ca2+ releasable by caffeine was also unaffected by cocaine. In the presence of the beta-adrenergic agonist isoproterenol, which caused a large enhancement of peak [Ca2+]i and contraction, cocaine still inhibited both parameters. However, cocaine did not reverse the ability of isoproterenol to enhance the rate of Ca2+ reuptake and cell relaxation. Whole cell voltage-clamp studies showed that 50 microM cocaine reduced both the Na+ current (50%) and the Ca2+ current (30%). These data suggest that sarcolemmal ion channels are the primary site that, in cardiac muscle, mediate the negative inotropic effects and the suppression of [Ca2+]i transients by cocaine.
Sweet Relief: Reprogramming Gastric Endocrine Cells to Make Insulin.

Two promising approaches toward a cell-based cure for diabetes are the directed differentiation of pluripotent stem cells or lineage reprogramming of other cell types to generate beta cells. In this issue of Cell Stem Cell, Ariyachet et al. (2016) reprogrammed gastric endocrine cells to generate a renewable source of insulin-producing cells.
The effect of quick freezing on the preservation of selected serum enzyme activities.

This study was undertaken to develop a technic for preserving the activities of serum glutamic oxalacetic transaminase, lactic acid dehydrogenase, and creatine phosphokinase in vitro . Fresh serum (4-ml. aliquots) was quickly frozen in a slush made of Dry Ice and acetone (temperature approximately –78 C ) , and then stored in an electric freezer (0 to –2 C ) . For comparison purposes, another group of serum samples was stored in a refrigerator at 4 C. The ultraviolet method with reduced diphosphopyridine nucleotide was used to measure the enzyme levels. Serum enzyme levels measured prior to quick freezing or cooling were compared with those after the serum had been frozen or cooled for 12, 24, and 48 hr. For all enzymes studied, there were no statistically significant differences ( p >0.10 in all cases) between the values measured prior to quick freezing and those measured 12, 24, and 48 hr. later. In direct contrast, statistically significant differences ( p ≥0.05 in all cases) were found between the enzyme levels of the precooled serum and the serum which had been refrigerated for 24 and 48 hr. If the quick freeze technic is utilized, selected days may be set aside in the laboratory for enzyme analysis, and samples collected over a 48-hr. period may be handled at this time.
Physiological Peripubertal Activation of the Ovary Is Not Reproduced by Pregnant Mare Serum Gonadotropin (PMSG) Administration

During the days preceding the first ovulation the ovary of the rat exhibits a remarkable increase in estradiol (E2) and progesterone (P) release in response to gonadotropins. No such increase is observed in the case of androgens (A, testosterone + dihydrotestosterone). The present experiments were undertaken to examine the possibility of reproducing these developmental events by stimulating the ovary with a gonadotropin that has substantial FSH-like activity. In vivo administration of pregnant mare serum gonadotropin (PMSG) to juvenile 29-day-old rats greatly increased the in vitro E2 and A response to human chorionic gonadotropin (hCG) measured 2 days later in the morning. The magnitude of the A response was significantly larger than that of ovaries from juvenile animals or rats in first proestrus. The E2 response was much greater than that of juvenile ovaries but similar to that of ovaries from late proestrous rats. In contrast, the P response to hCG was not enhanced by PMSG. In fact the response was similar to that of juvenile ovaries and markedly less than that of first proestrous rats. This decreased P response was not due to a greater conversion of P to its less active metabolite 20 alpha-hydroxy-4-pregnen-3-one (20 alpha-OH-P). The results suggest that PMSG enhances the E2 and A response of immature ovaries to hCG at the expense of that of P. Treatment of immature rats with PMSG may represent a useful model to study E2 release from preovulatory ovaries, but it cannot be used to reproduce in its entirety the developmental changes in steroidal response to gonadotropins associated with normal puberty.
Spectroscopic Ellipsometric Analysis of Surface and Subsurface Damage in Chemical-Mechanical Polished Semiconductors

Spectroscopic ellipsometry (SE), with the added capability of variable angle of incidence, is a sensitive technique for nondestructive surface and interface analysis. In this work, we demonstrate the application of this technique to the quantitative characterization of surface and subsurface damage in Si and GaAs, induced by conventional chemical-mechanical polishing. We show that the optimum selection of angle of incidence and spectral range is of crucial importance for detecting and evaluating surface and subsurface quality. To adequately describe the measured SE data, a two-layer model (i.e. oxide overlayer/subsurface damage layer/substrate) was found to be necessary. In this model, the oxide overlayer and subsurface damage layer were each modeled as a simple physical mixture of the chosen constituents, using the Bruggeman effective medium approximation. SE analysis clearly indicated the presence of surface microscopic roughness and subsurface damage for all the samples investigated. Typical results for thickness were 2 to 3 nm of surface overlayer, and 15 to 40 nm of damage beneath it, containing about 1 ∼ 2% volume fraction of either oxide or voids. As verification, atomic force microscopy (for surface characterization) and wet chemical oxide stripping (for subsurface analysis) were used to substantiate the SE results.
A turn-on fluorescent nanoprobe for selective determination of selenium(IV).

A turn-on fluorescent nanoprobe was developed for selective determination of selenium(IV). A trace amount of selenium, as an essential nutrient, plays an important role in human health. It has been proven that a selenium deficiency will result in serious health problems. The developed nanoprobe is capable of in situ detection of selenium with target-induced signaling, and no separation step is needed. The nanoprobe consists of a silica nanoparticle core and a coating layer containing selenium(IV)-induced fluorescent molecules, 3,3′-diaminobenzidine (DAB). The nanoprobes have no fluorescence signals if they are not exposed to selenium(IV). However, the nanoprobes will be “turned on”, with fluorescence, when they bind to the targets of selenium(IV). With this strategy, the selenium(IV) are first collected and enriched on a small domain of the nanoprobes. Then, with an excitation at 420 nm, the nanoprobes emit fluorescence signals at 530 nm. The fluorescence intensity is proportional to the selenium concentr...
Single-shot absolute 3D shape measurement with Fourier transform profilometry

Fourier transform profilometry (FTP) is one of the frequently adopted three-dimensional (3D) shape measurement methods due to its ability to recover single-shot 3D shapes, yet it is challenging to retrieve the absolute phase map solely from one single grayscale fringe image. This paper presents a computational framework that overcomes this limitation of FTP with digital fringe projection (DFP). By using geometric constraints, an absolute phase map can be retrieved point-by-point from one single grayscale fringe image. Experiments demonstrate the success of our proposed framework with single-shot absolute 3D shape measurement capability.
Three-dimensional electrocardiographic imaging

We review our recent work on the development and evaluation of three-dimensional electrocardiographic imaging technology (3DEIT). Cardiac electrophysiological properties, including activation time and transmembrane potentials, are estimated from body surface ECG signals with the aid of a realistic geometry heart model in which electrophysiological a priori information is incorporated. We have conducted computer simulation studies to demonstrate the feasibility of imaging activation sequence throughout the three-dimensional myocardium, and localizing sites of origin of activation and arrhythmias using our 3DEIT approach. We will also review the pilot experimental studies in evaluating the 3DEIT approach in a patient with pacemaker and experimental animals with intracardiac recordings. Our promising results to date suggest the feasibility of the 3DEIT technology that we are developing and that it merits further investigation.
Financing Need and the Choice Between Asset Sale and Security Issuance

Theoretical research identifies balance sheet, underinvestment, correlation, and timing effects for a firm’s financing choice between an asset sale and a seasoned equity offering (SEO). Ours is the first study that empirically validates these effects. We find the probability of an SEO increases with financing need (balance sheet effect) and past returns (timing effect). Whereas, the probability of an asset sale increases with financial leverage (underinvestment effect) and it is higher for a multisegment firm (correlation effect). The balance sheet effect strengthens for firms with high past returns and growth opportunities, and it weakens for firms with high financial leverage.
Old Age in Existentialist Perspective

Drawing mainly from Simone De Beauvoir’s The Coming of Age, Arp lays out what existentialism has to say about the experience of old age. She highlights the disconnect between the biological reality of old age and our inward experience of ourselves: old people feel the same inside, although the mirror tells a different story. However, their relation to the past, present, and future is different from that of younger people. The rigid habits they tend to adopt and the repercussions of past choices constrain their lives. They turn to their memories for solace, but these memories are fragmentary and seem unreal. Even success ultimately becomes disappointing. Nonetheless, according to existentialism, the old, like the young, can still find meaning in existence through throwing themselves into their chosen projects.