Evaluation of a long-time temperature drift in a commercial Quantum Design MPMS SQUID magnetometer using Gd2_2O3_3 as a standard

The long-time temperature drift in a commercial Quantum Design MPMS SQUID magnetometer was evaluated using time-dependent magnetization measurements of Gd$_2$O$_3$. In contrast to earlier claims, the amplitude of the drift was found not to exceed 1-1.5 K. 30 minutes after system stabilization the temperature deviation did not exceed 0.2 K and the temperature was fully stabilized in less than 3 hours

Toward a Jurisprudence of Psychiatric Evidence: Examining the Challenges of Reasoning from Group Data in Psychiatry to Individual Decisions in the Law

Psychiatry is an applied science. It thus shares a characteristic of all applied science in that it is ultimately applied at two levels—general and specific. Scientific research inevitably focuses on aggregate data and seeks to generalize findings across persons, places, or things. However, in the courtroom, as is true in other applied settings, the focus is usually on an individual case. Thus, psychiatry presents the challenge inherent in all scientific evidence of reasoning from group data to an individual case, which is termed the “G2i problem.” Psychiatry, unlike many scientific fields that come to court, also confronts the G2i problem in its daily practice since mental health professionals routinely diagnose and treat individuals based on aggregate data. Yet approaches to the G2i problem in clinical psychiatry do not necessarily comport with the ways in which aggregate data is applied to an individual case in the courtroom. In this Article, we employ the G2i lens to examine the admissibility of psychiatric expert testimony in regards to both general research findings, or “framework evidence,” and application of those general findings to specific cases, or “diagnostic evidence.” Although the rules of evidence that apply to “G” and to “i” are the same, the scientific and professional considerations with which each must be evaluated are fundamentally different. G2i inferences provide a useful lens by which the interactions of psychiatry and law can be better understood and managed

Universal point contact resistance between thin-film superconductors

A system comprising two superconducting thin films connected by a point contact is considered. The contact resistance is calculated as a function of temperature and film geometry, and is found to vanish rapidly with temperature, according to a universal, nearly activated form, becoming strictly zero only at zero temperature. At the lowest temperatures, the activation barrier is set primarily by the superfluid stiffness in the films, and displays only a weak (i.e., logarithmic) temperature dependence. The Josephson effect is thus destroyed, albeit only weakly, as a consequence of the power-law-correlated superconducting fluctuations present in the films below the Berezinskii-Kosterlitz-Thouless transition temperature. The behavior of the resistance is discussed, both in various limiting regimes and as it crosses over between these regimes. Details are presented of a minimal model of the films and the contact, and of the calculation of the resistance. A formulation in terms of quantum phase-slip events is employed, which is natural and effective in the limit of a good contact. However, it is also shown to be effective even when the contact is poor and is, indeed, indispensable, as the system always behaves as if it were in the good-contact limit at low enough temperature. A simple mechanical analogy is introduced to provide some heuristic understanding of the nearly-activated temperature dependence of the resistance. Prospects for experimental tests of the predicted behavior are discussed, and numerical estimates relevant to anticipated experimental settings are provided.Comment: 29 pages (single column format), 7 figure

Anisotropic Hall Effect in Single Crystal Heavy Fermion YbAgGe

Temperature- and field-dependent Hall effect measurements are reported for YbAgGe, a heavy fermion compound exhibiting a field-induced quantum phase transition, and for two other closely related members of the RAgGe series: a non-magnetic analogue, LuAgGe and a representative, ''good local moment'', magnetic material, TmAgGe. Whereas the temperature dependent Hall coefficient of YbAgGe shows behavior similar to what has been observed in a number of heavy fermion compounds, the low temperature, field-dependent measurements reveal well defined, sudden changes with applied field; in specific for $H \perp c$ a clear local maximum that sharpens as temperature is reduced below 2 K and that approaches a value of 45 kOe - a value that has been proposed as the $T = 0$ quantum critical point. Similar behavior was observed for $H \| c$ where a clear minimum in the field-dependent Hall resistivity was observed at low temperatures. Although at our base temperatures it is difficult to distinguish between the field-dependent behavior predicted for (i) diffraction off a critical spin density wave or (ii) breakdown in the composite nature of the heavy electron, for both field directions there is a distinct temperature dependence of a feature that can clearly be associated with a field-induced quantum critical point at $T = 0$ persisting up to at least 2 K.Comment: revised versio

Legionella pneumophila multiplication is enhanced by chronic AMPK signalling in mitochondrially diseased dictyostelium cells

Human patients with mitochondrial diseases are more susceptible to bacterial infections, particularly of the respiratory tract. To investigate the susceptibility of mitochondrially diseased cells to an intracellular bacterial respiratory pathogen, we exploited the advantages of Dictyostelium discoideum as an established model for mitochondrial disease and for Legionella pneumophila pathogenesis. Legionella infection of macrophages involves recruitment of mitochondria to the Legionella-containing phagosome. We confirm here that this also occurs in Dictyostelium and investigate the effect of mitochondrial dysfunction on host cell susceptibility to Legionella. In mitochondrially diseased Dictyostelium strains, the pathogen was taken up at normal rates, but it grew faster and reached counts that were twofold higher than in the wild-type host. We reported previously that other mitochondrial disease phenotypes for Dictyostelium are the result of the activity of an energy-sensing cellular alarm protein, AMP-activated protein kinase (AMPK). Here, we show that the increased ability of mitochondrially diseased cells to support Legionella proliferation is suppressed by antisense-inhibiting expression of the catalytic AMPK&alpha; subunit. Conversely, mitochondrial dysfunction is phenocopied, and intracellular Legionella growth is enhanced, by overexpressing an active form of AMPK&alpha; in otherwise normal cells. These results indicate that AMPK signalling in response to mitochondrial dysfunction enhances Legionella proliferation in host cells.<br /

Recruitment, growth and mortality of an Antarctic hexactinellid sponge, Anoxycalyx joubini.

Polar ecosystems are sensitive to climate forcing, and we often lack baselines to evaluate changes. Here we report a nearly 50-year study in which a sudden shift in the population dynamics of an ecologically important, structure-forming hexactinellid sponge, Anoxycalyx joubini was observed. This is the largest Antarctic sponge, with individuals growing over two meters tall. In order to investigate life history characteristics of Antarctic marine invertebrates, artificial substrata were deployed at a number of sites in the southern portion of the Ross Sea between 1967 and 1975. Over a 22-year period, no growth or settlement was recorded for A. joubini on these substrata; however, in 2004 and 2010, A. joubini was observed to have settled and grown to large sizes on some but not all artificial substrata. This single settlement and growth event correlates with a region-wide shift in phytoplankton productivity driven by the calving of a massive iceberg. We also report almost complete mortality of large sponges followed over 40 years. Given our warming global climate, similar system-wide changes are expected in the future

Therapy of pancreatic cancer via an EphA2 receptor-targeted delivery of gemcitabine.

First line treatment for pancreatic cancer consists of surgical resection, if possible, and a subsequent course of chemotherapy using the nucleoside analogue gemcitabine. In some patients, an active transport mechanism allows gemcitabine to enter efficiently into the tumor cells, resulting in a significant clinical benefit. However, in most patients, low expression of gemcitabine transporters limits the efficacy of the drug to marginal levels, and patients need frequent administration of the drug at high doses, significantly increasing systemic drug toxicity. In this article we focus on a novel targeted delivery approach for gemcitabine consisting of conjugating the drug with an EphA2 targeting agent. We show that the EphA2 receptor is highly expressed in pancreatic cancers, and accordingly, the drug-conjugate is more effective than gemcitabine alone in targeting pancreatic tumors. Our preliminary observations suggest that this approach may provide a general benefit to pancreatic cancer patients and offers a comprehensive strategy for enhancing delivery of diverse therapeutic agents to a wide range of cancers overexpressing EphA2, thereby potentially reducing toxicity while enhancing therapeutic efficacy

α-Adrenergic inhibition of proliferation in HepG2 cells stably transfected with the α1B-adrenergic receptor through a p42MAP kinase/p21Cip1/WAF1-dependent pathway

AbstractActivation of α1B adrenergic receptors (α1BAR) promotes DNA synthesis in primary cultures of hepatocytes, yet expression of α1BAR in hepatocytes rapidly declines during proliferative events. HepG2 human hepatoma cells, which do not express α1BAR, were stably transfected with a rat α1BAR cDNA (TFG2 cells), in order to study the effects of maintained α1BAR expression on hepatoma cell proliferation. TFG2 cells had a decreased rate of growth compared to mock transfected HepG2 cells as revealed by a decrease in [3H]thymidine incorporation into DNA. Stimulation of α1BAR with phenylephrine caused a further large reduction in TFG2 cell growth, whereas no effect on growth was observed in mock transfected cells. Reduced cell growth correlated with increased percentages of cells found in G0/G1 and G2/M phases of the cell cycle. In TFG2 cells, phenylephrine increased p42MAP kinase activity by 1.5- to 2.0-fold for up to 24 h and increased expression of the cyclin dependent kinase inhibitor protein p21Cip1/WAF1. Treatment of TFG2 cells with the specific MEK1 inhibitor PD98059, or infection with a −/− MEK1 recombinant adenovirus permitted phenylephrine to increase rather than decrease [3H]thymidine incorporation. In addition, inhibition of MAP kinase signaling by PD98059 or MEK1 −/− blunted the ability of phenylephrine to increase p21Cip1/WAF1 expression. In agreement with a role for increased p21Cip1/WAF1 expression in causing growth arrest, infection of TFG2 cells with a recombinant adenovirus to express antisense p21Cip1/WAF1 mRNA blocked the ability of phenylephrine to increase p21Cip1/WAF1 expression and to inhibit DNA synthesis. Antisense p21Cip1/WAF1 permitted phenylephrine to stimulate DNA synthesis in TFG2 cells, and abrogated growth arrest. These results suggest that transformed hepatocytes may turn off the expression of α1BARs in order to prevent the activation of a growth inhibitory pathway. Activation of this inhibitory pathway via α1BAR appears to be p42MAP kinase and p21Cip1/WAF1 dependent

Accurately measuring the abundance of benthic microalgae in spatially variable habitats

Although many studies measure the abundance of benthic microalgae (BMA), at the meters squared scale, comparing these studies is difficult due to the variety of sampling, extraction, and analysis techniques. This difficulty is exacerbated by the fact that BMA abundance has high spatial and temporal variability, at all spatial scales. A suitable standard sampling regimen would reduce variation in estimates due to different sample collection and processing greatly facilitating comparisons between studies. This study examined the effect of varying the volume of extraction solvent, sampling core diameter, and sample replication on BMA biomass estimates. Key findings, applicable to all spatial scales, to accurately determine biomass were the use of a minimum sediment to extraction solvent ratio of 1:2 and use of a sampling core diameter of 19 mm. Across a wide range of sediment types, at the meters squared scale and using spectrophotometric techniques, a minimum replication number of 8 was found to be appropriate. We report the significant effect coring depth and units of expression have on BMA biomass estimates across a range of sediment types, highlighting the potential pitfalls when comparing studies