cssi/SciSciGPT-SciSciNet huggingface dataset:
Work Function Trends and New Low-Work-Function Boride and Nitride Materials for Electron Emission Applications

LaB6 has been used as a commercial electron emitter for decades. Despite the large number of studies on the work function of LaB6, there is no comprehensive understanding of work function trends in the hexaboride materials family. In this study, we use Density Functional Theory (DFT) calculations to calculated trends of rare earth hexaboride work function and rationalize these trends based on the electronegativity of the metal element. We predict that alloying LaB6 with Ba can further lower the work function by ~0.2 eV. Interestingly, we find that alloyed (La, Ba)B6 can have lower work functions than either LaB6 or BaB6, benefitting from an enhanced surface dipole due to metal element size mismatch. In addition to hexaborides we also investigate work function trends of similar materials families, namely tetraborides and transition metal nitrides, which, like hexaborides, are electrically conductive and refractory and thus may also be promising materials for electron emission applications. We find that tetraborides consistently have higher work functions than their hexaboride analogues as the tetraborides having less ionic bonding and smaller positive surface dipoles. Finally, we find that HfN has a low work function of about 2.2 eV, making HfN a potentially promising new electron emitter material.
Geometric electrostatic particle-in-cell algorithm on unstructured meshes

We present a geometric particle-in-cell (PIC) algorithm on unstructured meshes for studying electrostatic perturbations with frequency lower than electron gyrofrequency in magnetized plasmas. In this method, ions are treated as fully kinetic particles and electrons are described by the adiabatic response. The PIC method is derived from a discrete variational principle on unstructured meshes. To preserve the geometric structure of the system, the discrete variational principle requires that the electric field is interpolated using Whitney 1-forms, the charge is deposited using Whitney 0-forms and the electric field is computed by discrete exterior calculus. The algorithm has been applied to study the ion Bernstein wave (IBW) in two-dimensional magnetized plasmas. The simulated dispersion relations of the IBW in a rectangular region agree well with theoretical results. In a two-dimensional circular region with fixed boundary condition, the spectrum and eigenmode structures of the IBW are obtained from simulations. We compare the energy conservation property of the geometric PIC algorithm derived from the discrete variational principle with that of previous PIC methods on unstructured meshes. The comparison shows that the new PIC algorithm significantly improves the energy conservation property.
Exploration and Coordination of Complementary Multi-Robot Teams in a Hunter and Gatherer Scenario

The hunter-and-gatherer approach copes with the problem of dynamic multirobot task allocation, where tasks are unknowingly distributed over an environment. This approach employs two complementary teams of agents: one agile in exploring (hunters) and another dexterous in completing (gatherers) the tasks. Although this approach has been studied from the task planning point of view in our previous works, the multirobot exploration and coordination aspects of the problem remain uninvestigated. This paper proposes a multirobot exploration algorithm for hunters based on innovative notions of “expected information gain” to minimize the collective cost of task accomplishments in a distributed manner. Besides, we present a coordination solution between hunters and gatherers by integrating the novel notion of profit margins into the concept of expected information gain. Statistical analysis of extensive simulation results confirms the efficacy of the proposed algorithms compared in different environments with varying levels of obstacle complexities. We also demonstrate that the lack of effective coordination between hunters and gatherers significantly distorts the total effectiveness of the planning, especially in environments containing dense obstacles and confined corridors. Finally, it is statistically proven that the overall workload is distributed equally for each type of agent which ensures that the proposed solution is not biased to a particular agent and all agents behave analogously under similar characteristics.
On the Linear Capacity of Conditional Disclosure of Secrets

Conditional disclosure of secrets (CDS) is the problem of disclosing as efficiently as possible, one secret from Alice and Bob to Carol if and only if the inputs at Alice and Bob satisfy some function f. The information theoretic capacity of CDS is the maximum number of bits of the secret that can be securely disclosed per bit of total communication. All CDS instances, where the capacity is the highest and is equal to 1/2, are recently characterized through a noise and signal alignment approach and are described using a graph representation of the function f, G f . In this work, we go beyond the best case scenarios and further develop the alignment approach to characterize the linear capacity of a class of CDS instances to be (p- 1)/(2p), where $p$ is a covering parameter of G f .
Portfolio Growth Rate and Ergodic Capacity of Fading Channels

A relationship between the growth-rate of log-optimal portfolios and capacity of fading single-input multiple output (SIMO) channels are established. Using this relation, stock vector stochastic processes that model the investment environments are stochastically ordered using different criteria. The presence of side information (SI) is considered, and a bound on the gains in the growth-rate due to SI is derived along with data processing inequality and convexity properties. A statistical test on the usefulness of SI that does not require the computation of the optimal portfolio vector in the presence of SI is introduced and its several variants are discussed.
Removal of singularities from the covariant spectator theory

A modification of the one boson exchange (OBE) kernel for the covariant spectator theory (CST) is presented and discussed. When applied to the scattering of two identical particles, the previously used kernels either introduced spurious singularities, or removed them in an ad-hoc way. The new modification not only removes these singularities, but also maintains the convergence of the two-body CST equation (sometimes called the Gross equation) when used to describe the scattering of two identical scalar particles.
Perturbed recombination from inhomogeneous photon injection and application to accreting primordial black holes

Exotic electromagnetic energy injection in the early Universe may alter cosmological recombination, and ultimately cosmic microwave background (CMB) anisotropies. Moreover, if energy injection is inhomogeneous, it may induce a spatially varying ionization fraction, and non-Gaussianity in the CMB. The observability of these signals, however, is contingent upon how far the injected particles propagate and deposit their energy into the primordial plasma, relative to the characteristic scale of energy injection fluctuations. In this study we inspect the spatial properties of energy deposition and perturbed recombination resulting from an inhomogeneous energy injection of sub-10 MeV photons, relevant to accreting primordial black holes (PBHs). We develop a novel Monte Carlo radiation transport code accounting for all relevant photon interactions in this energy range, and including secondary electron energy deposition efficiency through a new analytic approximation. For a specified injected photon spectrum, the code outputs an injection-to-deposition Green's function depending on time and distance from the injection point. Combining this output with a linearized solution of the perturbed recombination problem, we derive time- and scale-dependent deposition-to-ionization Green's functions. We apply this general framework to accreting PBHs, whose luminosity is strongly spatially modulated by supersonic relative velocities between cold dark matter and baryons. We find that the resulting spatial fluctuations of the free-electron fraction are of the same magnitude as its mean deviation from standard recombination, from which current CMB power spectra constraints are derived. This work suggests that the sensitivity to accreting PBHs might be substantially improved by propagating these inhomogeneities to CMB anisotropy power spectra and non-Gaussian statistics, which we study in subsequent papers.
FTO Suppresses STAT3 Activation and Modulates Proinflammatory Interferon-Stimulated Gene Expression

Signaling initiated by type I interferon (IFN) results in the induction of hundreds of IFN-stimulated genes (ISGs). The type I IFN response is important for antiviral restriction, but aberrant activation of this response can lead to inflammation and autoimmunity. Regulation of this response is incompletely understood. We previously reported that the mRNA modification m6A and its deposition enzymes, METTL3 and METTL14 (METTL3/14), promote the type I IFN response by directly modifying the mRNA of a subset of ISGs to enhance their translation. Here, we determined the role of the RNA demethylase fat mass and obesity-associated protein (FTO) in the type I IFN response. FTO, which can remove either m6A or cap-adjacent m6Am RNA modifications, has previously been associated with obesity and body mass index, type 2 diabetes, cardiovascular disease, and inflammation. We found that FTO suppresses the transcription of a distinct set of ISGs, including many known pro-inflammatory genes, and that this regulation requires its catalytic activity but is not through the actions of FTO on m6Am. Interestingly, depletion of FTO led to activation of the transcription factor STAT3, whose role in the type I IFN response is not well understood. This activation of STAT3 increased the expression of a subset of ISGs. Importantly, this increased ISG induction resulting from FTO depletion was partially ablated by depletion of STAT3. Together, these results reveal that FTO negatively regulates STAT3-mediated signaling that induces proinflammatory ISGs during the IFN response, highlighting an important role for FTO in suppression of inflammatory genes.
Distributionally Robust Optimization with Confidence Bands for Probability Density Functions

Distributionally robust optimization (DRO) has been introduced for solving stochastic programs in which the distribution of the random variables is unknown and must be estimated by samples from tha...
A Comparative Study of Imputation Methods for Multivariate Ordinal Data

Missing data remains a very common problem in large datasets, including survey and census data containing many ordinal responses, such as political polls and opinion surveys. Multiple imputation (MI) is usually the go-to approach for analyzing such incomplete datasets, and there are indeed several implementations of MI, including methods using generalized linear models, tree-based models, and Bayesian non-parametric models. However, there is limited research on the statistical performance of these methods for multivariate ordinal data. In this article, we perform an empirical evaluation of several MI methods, including MI by chained equations (MICE) using multinomial logistic regression models, MICE using proportional odds logistic regression models, MICE using classification and regression trees, MICE using random forest, MI using Dirichlet process (DP) mixtures of products of multinomial distributions, and MI using DP mixtures of multivariate normal distributions. We evaluate the methods using simulation studies based on ordinal variables selected from the 2018 American Community Survey (ACS). Under our simulation settings, the results suggest that MI using proportional odds logistic regression models, classification and regression trees and DP mixtures of multinomial distributions generally outperform the other methods. In certain settings, MI using multinomial logistic regression models is able to achieve comparable performance, depending on the missing data mechanism and amount of missing data.
Ultrafast Focus Detection for Automated Microscopy

Recent advances in scientific instrumentation technology have led to an increase in the volumes and velocities of data being generated in typical laboratories. Such advanced instruments now necessitate commensurately advanced computing resources and techniques to realize their full potential. In particular, such as in the case of quality control for automated microscopes collecting large volumes of images. We propose a faster than real-time “out-of-focus” detection algorithm for electron microscopy images. Our technique, Multi-scale Histologic Feature Detection (MHFD), adapts classical computer vision techniques and is based on detecting various fine-grained histologic features. We also study the inherent parallelism in the technique in order to employ GPU accelerators. We present preliminary tests that demonstrate the efficacy of MHFD and discuss applying our solution to images produced by a scanning electron microscope in an active connectomics laboratory.
Resurgent Na+ currents promote ultrafast spiking in projection neurons that drive fine motor control.

The underlying mechanisms that promote precise spiking in upper motor neurons controlling fine motor skills are not well understood. Here we report that projection neurons in the adult zebra finch song nucleus RA display robust high-frequency firing, ultra-narrow spike waveforms, superfast Na+ current inactivation kinetics, and large resurgent Na+ currents (INaR). These properties of songbird pallial motor neurons closely resemble those of specialized large pyramidal neurons in mammalian primary motor cortex. They emerge during the early phases of song development in males, but not females, coinciding with a complete switch of Na+ channel subunit expression from Navβ3 to Navβ4. Dynamic clamping and dialysis of Navβ4’s C-terminal peptide into juvenile RA neurons provide evidence that Navβ4, and its associated INaR, promote neuronal excitability. We thus propose that INaR modulates the excitability of upper motor neurons that are required for the execution of fine motor skills. The zebra finch robust nucleus of the arcopallium (RA) directs singing by providing descending projections to brainstem motor neurons. The authors show that electrophysiological characteristics of RA neurons rely on resurgent Na+ currents that emerge early during song development only in males.
ResNEsts and DenseNEsts: Block-based DNN Models with Improved Representation Guarantees

Models recently used in the literature proving residual networks (ResNets) are better than linear predictors are actually different from standard ResNets that have been widely used in computer vision. In addition to the assumptions such as scalar-valued output or single residual block, these models have no nonlinearities at the final residual representation that feeds into the final affine layer. To codify such a difference in nonlinearities and reveal a linear estimation property, we define ResNEsts, i.e., Residual Nonlinear Estimators, by simply dropping nonlinearities at the last residual representation from standard ResNets. We show that wide ResNEsts with bottleneck blocks can always guarantee a very desirable training property that standard ResNets aim to achieve, i.e., adding more blocks does not decrease performance given the same set of basis elements. To prove that, we first recognize ResNEsts are basis function models that are limited by a coupling problem in basis learning and linear prediction. Then, to decouple prediction weights from basis learning, we construct a special architecture termed augmented ResNEst (A-ResNEst) that always guarantees no worse performance with the addition of a block. As a result, such an A-ResNEst establishes empirical risk lower bounds for a ResNEst using corresponding bases. Our results demonstrate ResNEsts indeed have a problem of diminishing feature reuse; however, it can be avoided by sufficiently expanding or widening the input space, leading to the above-mentioned desirable property. Inspired by the DenseNets that have been shown to outperform ResNets, we also propose a corresponding new model called Densely connected Nonlinear Estimator (DenseNEst). We show that any DenseNEst can be represented as a wide ResNEst with bottleneck blocks. Unlike ResNEsts, DenseNEsts exhibit the desirable property without any special architectural re-design.
Resistivity size effect due to surface steps on ruthenium thin films computed with a realistic tight-binding model

A realistic tight-binding model is developed and employed to elucidate the resistivity size effect due to steps on Ru thin films. The resistivity of two different film orientations, (0001) and (11¯00), is computed for transport along the [112¯0] direction both for smooth surfaces and for surfaces with monolayer-high steps. In the case of smooth films, the systems are also studied using solutions to the Boltzmann transport equation. Interestingly, the resistivity of (11¯00) surfaces exhibits a significant size effect even in the absence of surface steps. When monolayer-high steps are spaced ∼10 nm apart, the resistivity is shown to increase due to scattering from the steps. However, only a small increase was found which cannot explain the large effect seen in recent experiments with Ru thin films. This highlights the need for further elucidation of the resistivity size effect. Theoretical analysis suggests that films made from materials with a relatively large ballistic conductance per area like Ru should exhibit a reduced resistivity size effect. This result points to Ru as a promising interconnect material. Finally, because a very efficient algorithm for computing resistivity based on the kernel polynomial method is used, the approach fulfills a need for realistic models that can span length scales directly relevant to experimental results. The calculations described here include films approaching 5 nm in thickness, with in-plane distances up to ∼160 nm and 3.8×105 atomic sites.
Geographic and temporal variation in housing filtering rates

Abstract In the field of Housing Economics, filtering is the process by which properties, as they age and depreciate in quality, tend to be occupied by lower-income households. This is the primary mechanism by which competitive markets supply low-income housing. While filtering is an important long-term source of lower-income housing at the national level, this research shows that filtering rates for owner-occupied properties vary considerably both across and within metropolitan statistical areas. Notably, in some markets, properties “filter up” to higher-income households. This paper contributes to our understanding of filtering by demonstrating the geographic and temporal heterogeneity of filtering rates and examining links between filtering, supply elasticity, and gentrification. We also explore two alternative measures of filtering based on changes in relative income rather than real income.
Enhanced dissipation, hypoellipticity for passive scalar equations with fractional dissipation

Abstract We consider the passive scalar equations subject to shear flow advection and fractional dissipation. The enhanced dissipation estimates are derived. For the classical passive scalar equation ( γ = 1 ), our result agrees with the sharp one obtained in [46] .
Surface Structures from LEED: Metal Surfaces and Metastable Phases

We review two notable achievements of low-energy electron diffraction (LEED) research: (1) the discovery and study of surface relaxation and (2) the identification and characterization of epitaxially-grown metastable phases. Both achievements are linked to the ability of LEED to determine the atomic structure of 4–5 layers of atoms on crystal surfaces. To be sure, other surface-sensitive techniques have structure capabilities, notably high-, medium-, and low-energy ion scattering spectroscopy (HEISS, MEISS, LEISS), surface extended X-ray absorption fine structure (SEXAFS), and high-energy electron diffraction (HEED), but LEED has been, to date, the most productive technique with regard to the achievments mentioned above.
Male Sterility and Hybrid Production Systems

The ability to exploit the long known phenomenon of hybrid vigor or heterosis, the superior performance of the F1 hybrid compared to either parent line, has greatly impacted the goal of production agriculture to meet world food demands. Hybrid production systems rely on an efficient and effective mechanism for inducing male sterility in one of the parental lines in order to ensure purity of the resultant hybrid seed. Natural male sterility systems are available but are limited in their availability for all crops and their effectiveness in those for which they have been developed. This chapter discusses the means by which modern techniques of genetic engineering have broadened our ability to develop male sterile lines and improve hybrid production strategies. The chapter discusses the development of dominant male sterility systems using genetic ablation and developmental disruption strategies, conditional male sterility strategies and the genetic engineering of maintainer lines. The generation of novel and improved systems for hybrid production in the ongoing search for crop improvement has been, and continues to be, one of the major targets for transgenic manipulations within the agricultural biotechnological community.
Mars sample return, a concept point design by Team-X (JPL's advanced project design team)

A Mars sample return mission will answer critical questions concerning the possibility of life on Mars. Shallow drilling from the Lander provides pristine samples while the rover provides samples from a variety of sites. Included are discussions of a Mars sample return mission point design where requirements development, mission design, flight system design and identification of technology developments needed to enable the mission are presented. After launch on a Delta IV Heavy launch vehicle, the Lander and Orbiter are separated and individually guided to Mars. The Lander is targeted for direct atmospheric entry where it will use active aerodynamic control to arrive within a few kilometers of the landing site. After surface operations the Mars Ascent Vehicle is launched into low Mars orbit where the Orbiter, after Mars orbit insertion and aero-braking, has arrived to rendezvous with the sample. Once the sample is placed in the Earth Entry Vehicle (EEV), the Orbiter returns the EEV for direct Earth entry. Many technology advances are needed to enable a Mars sample return mission. The spacecraft must be able to perform an autonomous landing on Mars while avoiding hazards. An autonomous Mars launch system will need to be developed along with an autonomous system for rendezvous and capture of the sample.
Computer implementation of an algorithm for the quadratic analytical solution of Hamiltonian systems

Abstract A software package for the analytical solution of Hamiltonians defining perturbed periodic motion is described. Features of the algorithm are reviewed briefly, and options and systems requirements of the program are indicated. Finally, Duffing's equation illustrates a typical run in which frequencies through seventh order and solutions through third—both expressed in terms of canonical variables, and then in terms of the original amplitude—are found in only two algorithm steps.
The effects of caloric restriction on the travel and manipulation components of human motion.

Electronic techniques of motion analysis have been used to evaluate the effects of a restricted diet on travel and manipulation components of motion. 13 subjects were tested at regular intervals during the 3 phases of the experiment: (a) a 21-day control period, (b) a 24-day period of maintenance on a 1000 calorie, all-carbohydrate diet, and (c) a 21-day recovery period. 2 conditions of pacing were employed: a 10-minute period of continuous performance at a “normal” or “comfortable” pace, and a 2-minute period of continuous performance at a “maximum” pace. The results of the study may be summarized as follows: 1. Travel times increase significantly during food restriction under both conditions of pacing. 2. No significant change in manipulation times attributable to food restriction is evident under either condition of pacing. 3. A significant work decrement is apparent only in manipulation movevements under maximum pacing. 4. Work decrements do not change significantly as a function of nutritional deficit for either motion component.
Self-injectable Epinephrine for First-Aid Management of Anaphylaxis: In Reply

We thank Drs Gaines and Shaker et al for their thoughtful comments. We fully agree that it is not always easy to assess the clinical risk of future anaphylaxis, which influences the decision to prescribe self-injectable epinephrine.1 We overstated the risk of subsequent anaphylaxis in children with generalized acute urticaria (mild cutaneous systemic reactions) after an insect sting as ∼10%. It is, in fact, precisely 6.74% as …
Anisotropic magnetoresistance of Co-Fe alloys and the effect of atomic ordering

Abstract The anisotropic magnetoresistance Δϱ/ϱ 0 has a sharp peak near 50 at% Co, which is related to the ordered CsCl structure existing at that composition. We distinguish the effect of short and long-range order on Δϱ/ϱ 0 by quenching one sample from several temperatures T Q above and below the ordering temperature T o , and measuring Δϱ/ϱ 0 ( T Q ) at 4.2 K.
Inverse relationship of cotranslational translocation with the hydrophobic moment of the bovine preproparathyroid hormone signal sequence

To investigate the dependence of transmembrane translocation on the hydrophobic moment of the hydrophobic core of the preproparathyroid hormone signal sequence, amino acids were switched to maximize or minimize the hydrophobic moment without changing the length or overall hydrophobicity of the core. As assayed in an in vitro translation system with microsomal membranes, the efficiency of translocation of these mutants was inversely related to the hydrophobic moment, indicating the hydrophobic moment or a related property may contribute to translocational activity.
Alzheimer amyloid-β oligomer bound to postsynaptic prion protein activates Fyn to impair neurons

Amyloid-beta (Aβ) oligomers are thought to trigger Alzheimer's disease pathophysiology. Cellular prion protein (PrP(C)) selectively binds oligomeric Aβ and can mediate Alzheimer's disease-related phenotypes. We examined the specificity, distribution and signaling of Aβ-PrP(C) complexes, seeking to understand how they might alter the function of NMDA receptors (NMDARs) in neurons. PrP(C) is enriched in postsynaptic densities, and Aβ-PrP(C) interaction leads to Fyn kinase activation. Soluble Aβ assemblies derived from the brains of individuals with Alzheimer's disease interacted with PrP(C) to activate Fyn. Aβ engagement of PrP(C)-Fyn signaling yielded phosphorylation of the NR2B subunit of NMDARs, which was coupled to an initial increase and then a loss of surface NMDARs. Aβ-induced dendritic spine loss and lactate dehydrogenase release required both PrP(C) and Fyn, and human familial Alzheimer's disease transgene-induced convulsive seizures did not occur in mice lacking PrP(C). These results delineate an Aβ oligomer signal transduction pathway that requires PrP(C) and Fyn to alter synaptic function, with deleterious consequences in Alzheimer's disease.
Bounds for the number of moduli for irregular varieties of general type.

LetX be a minimal surface of general type and M (X) the set of equivalence classes of complex structures on the differentiable manifold underlyingX; denoting byMx the dimension of M(X) at [X], the point corresponding to the complex structure ofX we consider the problem of finding an upper bound forMx in terms of the basic numerical invariants ofX. The main result is the Castelunovo's bound:Mx≤Pg(X)+2q(X) for certain irregular surfaces. We also generalize the above bound to an arbitrary dimension.
A reexamination of the `lemons' market when warranties are not prepurchase quality signals

Abstract It is well known that the Akerlof “lemons” problem may occur when sellers possess private information about product quality and that the use of warranties as prepurchase quality signals may mitigate both the informational asymmetry and the attendant market failure. There is, however, evidence suggesting that consumers rarely read and compare alternative warranties before reaching a purchase decision, which casts doubt on the role of warranties as prepurchase quality signals. This paper examines an environment in which the cost to consumers of interpreting warranty terms is prohibitively high so that warranties do not serve in a prepurchasing signalling capacity. Nonetheless, I find that firms will offer warranties in this environment and that the market outcome is often Pareto superior, and never Pareto inferior, to an equilibrium where warranties serve as prepurchase quality signals.
Long-term maintenance of receptivity by subcutaneous implants of estradiol

Abstract Ovariectomized female rats were implanted with Silastic capsules which were either empty (Controls) or contained one of two concentrations of estradiol in oil. The two experimental capsules released levels of estradiol for 7–14 days which resembled either proestrous or diestrus II serum values, then decreased to low levels. In both experimental groups all animals showed sexual receptivity by Day 7 and this response was maintained through Day 32. While no differences in lordosis quotients were found between experimental groups on Days 7 or 11, by Day 14 the group with the less concentrated estradiol capsule showed a significantly lower LQ response, which was maintained until the termination of testing. There was no evidence for day-night differences in receptivity in any estradiol-implanted animals. Body weights declined in a dose-dependent fashion within 3 days after implantation of the estradiol capsules. Weights then began to recover by 11 days after implantation, but remained significantly below those of ovariectomized controls with empty implants for the duration of the experiment.
Disulfiram, an old drug with new potential therapeutic uses for human cancers and fungal infections

Disulfiram, a drug used to treat alcoholism, has recently been indicated to play a primary as well as an adjuvant role in the treatment of many cancers and in the reversal of fungal drug-resistance. This review discusses the molecular mechanism of action of disulfiram and its potential use in the treatment of human cancers and fungal infections.
Monoclonal antibody for identification of human duct cell carcinoma of pancreas

Abstract Monoclonal antibody to duct cell surface marker (HP-DU-1), produced by hybridoma, was shown to be specific to duct cell surface antigen when tested against normal adult and 12–20-week-old fetal human pancreases. There were no common HLA antigens for locus A, B, C and DR among the 10 pancreas donors; nor did HP-DU-1 reveal any affinity for lymphocytes of donors whose pancreases were used as antigen for immunization of BALB c mice. Seven out of 7 human pancreas adenocarcinomas including a poorly differentiated human pancreatic tumor expressed surface determinants detectable by HP-DU-1. Cell lines CAPAN-1 and CAPAN-2, derived from human pancreatic adenocarcinoma, also revealed the same antigenic determinants.
Association of cellular membrane of E. coli minicells with the origins/terminus region of replication of plasmid ColEl DNA

COLICINOGENIC plasmid El (ColEl) can be isolated from Escherichia coli as a supercoiled DNA molecule of 2.14 µm long or as a supercoiled DNA–protein complex1. Certain protein denaturing agents will convert this complex to an open circular (relaxed) DNA form with one single-strand break in the heavy (polyUG binding) strand of the duplex ColEl DNA (refs 2, 3). The induced single-strand break in ColEl DNA is located approximately 19% of the length of ColEl DNA from the single EcoRI restriction endonuclease site in the plasmid4. Analysis of ColEl replicating intermediates has shown that replication proceeds unidirectionally from an origin located near the position of the relaxation complex nick, approximately 19% from the single EcoRI restriction site 5–7. The site of the relaxation-complex nick has been located approximately 300 nucleotides away from the origin of ColEl DNA replication9. The nucleotide sequence of the origin region of ColEl DNA8,9 and of a small ColEl-type plasmid10 have been determined. A model for the possible role of the relaxation complex in ColEl DNA replication and/or conjugal transfer has been presented11. A major feature of this model is that the relaxation complex proteins may help promote association of plasmid DNA with a replicator and/or conjugal transfer site on the bacterial membrane. We describe here an electron microscopic analysis of EcoRI-cleaved ColEl and mini-ColEl DNA that were purified as stable DNA–membrane complexes from E. coli minicells. Evidence is presented that membrane-like structures attach to ColEl DNA and mini-ColEl DNA in a region that includes both the site of the origin/terminus of DNA replication and the site of single-strand cleavage by the relaxation complex.
Nucleotide variations in the lxd region of Drosophila melanogaster: characterization of a candidate modifier of lifespan.

Abstract We have investigated the structure and function of several proteins that might influence adult lifespans in Drosophila melanogaster. The present report focuses on the gene lxd (‘low xanthine dehydrogenase’), which lies in a region of chromosome III identified by QTL-mapping as potentially important for lifespan. DNA sequence of a 3780 bp genomic fragment containing the lxd locus reveals differences between long-lived and control inbred lines. In order to determine the importance of nucleotide replacements, the intron/exon boundaries have been determined, based on peptide alignment and conserved amino acids. We identified four exons in the lxd coding region. The deduced amino acid sequence of exon 4 shows 46.5% identity with Escherichia coli MoaC sequences. There are eight nucleotide substitutions in exons differentiating the inbred lines, three in exon 3 and five in exon 4. One of the exon 4 substitutions has resulted in a Thr–Ile replacement at the protein surface, but not entirely solvent exposed. This substitution is potentially a modifier of lifespan via oxygen defense, but since the activities of three molybdoenzymes are unaffected in inbred lines, this possibility seems remote.
Natural killer cell immune responses

Natural killer (NK) cells play a vital role in innate immune responses to infection; they express activation receptors that recognize virus-infected cells. Highly related to receptors recognizing tumor cells, the activation receptors trigger cytotoxicity and cytokine production. NK cells also express inhibitory receptors for major histocompatibility complex (MHC) class I molecules that block the action of the activation receptors. Although many ligands for NK cell receptors have MHC class I folds, recent studies also indicate ligands resembling the NK cell receptors themselves. A combination of immunologic, genetic, biophysical, and in vivo approaches is being employed to understand fully how these receptors contribute to NK cell activities in innate immunity to pathogens and tumors.
Cultivating nursing leadership for our envisioned future.

Nurses have been called upon to lead and partner in the transformation of health care. Leadership is a component of the scope of nursing practice; however, the optimal approach to development of leadership competency has not been established. A metasynthesis of qualitative studies on leadership development was conducted to enhance an understanding of conditions that nurses reported to support or hinder their development as leaders. Noblit and Hare’s approach was used for the metasynthesis process. Three overarching themes emerged. Opportunity structure, the relationship factor, and organizational culture are essential factors contributing to the successful cultivation of leadership competencies in nurses. Key words: context, development, leadership, metasynthesis, praxis, transformation
A study of the atmospheric energetics of a six-layer operational forecast model

Verification data for twice-daily analyses of horizontal wind and temperature are compared with 00, 12, 24, 36, 60, and 84 hour forecasts prepared for winter 1975-76 from a six-layer operational forecast model; the comparison focuses on certain energy components in the forecast fields. Significant losses (15 to 20%) of zonal available potential energy and zonal kinetic energy appear beyond the 36-hour forecasts; the zonal kinetic energy loss is associated with a large increase in this parameter during the first 12-hour forecast period, due to a downward and northward movement of the mean jet-stream core. In addition, energy losses in the eddy potential and kinetic energy components are noted in the initialization procedure.
Behaviour after cerebral lesions in children and adults.

SUMMARY Animal experiments tend to show that brain injuries sustained early in life have less effect than comparable lesions incurred at later stages. By contrast, neurological observations suggest that certain forms of early brain damage in children may have disproportionately serious consequences for later development. The apparent contradiction may be resolved if one grants that results might differ, according to (a) the kind of task employed, and (b) the age at which the child is tested. Three perceptual tasks have been devised which disclose such differential effects. On one task, the effects of early injury are not apparent before the age of 11 years, but become increasingly obvious thereafter. On the second, a deficit is manifest at all ages. The third reveals effects of early injury only up to the age of 1 1 years; no abnormality can be discovered after this age. RESUME Comportement conskccutif aux Iksions ckrkbrales chez les enfants et les adultes L'exptrimentation sur des animaux tend a montrer que les ltsions ctrtbrales subies precocement ont des rtpercussions moindres que les Esions subies plus tard. Au contraire, les observations neurologiques suggkrent que certaines formes de ltsions ctrtbrales prtcoces peuvent avoir des consequences proportionnellement beaucoup plus graves pour le dtveloppement ulttrieur. Cette contradiction apparente s'explique si l'on admet que les rtsultats peuvent difftrer selon (a) la nature de la tBche proposte, et (6) 1'Bge auquel l'enfant est testt. Trois t2ches de perception ont ttt mises au point qui dCcklent ces effets differentiels. Avec une de ces tgches, les effets de la ltsion prtcoce n'apparaissent pas avant l'iige de onze ans, mais deviennent de plus en plus apparents a partir de cet Bge. Avec la seconde, le deficit est manifeste a tous les Bges. La troisikme tBche ne rtvkle les effets de la ltsion prtcoce que jusqu'a l'gge de onze ans; aucune anomalie ne peut tredkcelte 21 partir de cet 2ge. ZUSAMMENFASSUNG Das Benehrnen nach Gehirnschadigungen bei Kindern und Erwachsenen Tierexperimente deuten darauf hin, dass fruh erlittene Gehirnschadigungen geringere Folgen haben als vergleichbare spater entstandene Schadigungen. Neurologische Beobachtungen weisen im Gegenteil darauf hin, dass gewisse Formen von fruhen Gehirnschadigungen bei Kindern unverhaltnissmassig schwerere Folgen fur die spatere Entwicklung haben konnen. Dieser scheinbare Widerspruch kann beseitigt werden, wenn man annimmt. dass die Resultate verschieden sein konnen je nach (a) der Art der Aufgabe, und (b) dem Alter in dem das Kind untersucht wird. Drei Wahrnehmungsaufgaben sind erfunden worden. die diese Differenzialeffekte an den Tag bringen. Bei einer dieser Aufgaben erscheinen die Folgen des friih erlittenen Schadens nicht vor dem Alter von elf Jahren aber nehmen danach augenfallig zu. Bei der zweiten ist ein Defizit in allen Altersstufen offenbar. Die dritte zeigt die Folgen des friih erlittenen Schadens nur bis zum Alter von elf Jahren; nach diesem Alter kann keine Anomalie entdeckt werden.
Chemical Relations between Keweenawan Lavas and the Duluth Complex, Minnesota

Keweenawan basalt analyses having high Al2O3 and CaO contents fall on a linear trend on a CaO versus A12O3 plot. Using plagioclase and augite compositions from the gabbroic anorthosites of the Duluth complex, it is possible to explain the basalt trend by separation of gabbroic anorthosites from a melt rich in A12O3 and CaO. Calculations of the amount of solidification indicate that as much as 60 percent solid material separated before other gabbroic rock types crystallized from the melt. Trends of MgO, FeO, and K2O suggest that another fractionation may have preceded the separation of gabbroic anorthosite. An important conclusion from these arguments is that the multiple intrusions of the Duluth complex represent the crystalline material in magma chambers from which the Keweenawan flows of Lake Superior's North Shore were derived.
The debate about marijuana usage in transplant candidates: recent medical evidence on marijuana health effects.

Purpose of reviewCannabis is currently the most widely used illicit substance in the world. The issue of how to handle transplant candidates with active use of cannabis is a commonly encountered one for transplant-selection committees.Recent findingsCorrelates of marijuana use include increased risk
Mechanical characterization of several ion-implanted alloys: nanoindentation testing, wear testing and finite element modeling☆

Abstract The influence of ion implantation on the mechanical properties of metal alloys has been examined using a variety of experimental and numerical techniques. Ultralow load indentation testing and finite element modeling has been used for the aluminum/oxygen to extract fundamental mechanical properties. Aluminum implanted with 20 at.% O exhibits extraordinary strength, as high as 3300 MPa. The degree of strengthening expected for this Al(O) alloy on the basis of the observed microstructure of fine (1.5–3.5 nm) oxide precipitates was estimated using several micromechanical models, and the results agree with our experimental findings. Pin-on-disk tribological characterization of aluminum implanted with 10 at.% oxygen revealed that the ion-beam treatment reduced the average friction coefficient from greater than 1.0 (for pure Al) to approximately 0.25 (for Al(O)). Large-amplitude stick-slip oscillations, which occur within the first two cycles for pure aluminum, were postponed to 30–50 cycles for the ion-implanted material. Two stainless steels which have been amorphized by implantation, 304 implanted with C and 440C implanted with Ti + C, show measurable hardening with implantation, of the order of 40 and 15%, respectively. In addition, nanoindentation within pin-on-disk wear tracks on 440C reveals that the mechanical state of the extensively deformed implanted layer is apparently unchanged from its initial state.
A Circadian susceptibility-resistance cycle to fluothane in male B1 mice

The mortality of mature, male B1 mice upon exposure to 35 per cent Fluothane in oxygen for 10 minutes may be as low as 5 per cent oi as high as 76 per cent, depending upon the oiganism’s circadian system phase, Predictably peiiodic changes in susceptibility can be found in test animals of several age groups, apart from differences in susceptibility as a function of age Further consideration of the organism’s time structure, as revealed by its rhythms, may lead to safer anaesthetic practices.
Background subtraction for the Cluster/CODIF plasma ion mass spectrometer

Abstract. The CODIF instrument on the Cluster spacecraft is a time-of-flight (TOF) ion mass spectrometer. Although TOF spectrometers are relatively immune to background contamination due to the inherent double coincidence requirement, high background rates can still result in false coincidences. Along the Cluster orbit, false coincidences are commonly observed due to the penetrating radiation of relativistic electrons during the encounters with the Earth's radiation belts. A second type of background in these instruments occurs when events of one species fall into the time-of-flight range defined for another species. Although the fraction of the H+ events that spill into the He+ measurement is small, when the actual He+ fluxes are low this can result in significant contamination. In this paper we present two techniques that allow the subtraction of the false coincidences and the H+ "spill" from the CODIF measurements.
New traps for H0 in p-type Si

Abstract The equilibrium geometries, electronic structures, and relative stabilities of a variety of traps for interstitial H 0 in boron-doped and intrinsic Si have been obtained near the ab initio Hartree-Fock level. The calculations are done in clusters containing up to 48 host atoms. The 13 configurations considered are (a) nine configurations of a complex with substitutional boron and two hydrogen interstitials, (b) a {B,H} pair and a separate bond-centered hydrogen (H ∗ ), (c) the H 2 ∗ configuration, the H 2 molecule, and two isolated H ∗ 's. It is shown for the first time that the lowest-energy configuration is one of the {B,H,H} complexes. Without boron, H 2 ∗ is energetically preferred over H 2 .
Task-based optimization of dedicated breast CT via Hotelling observer metrics.

Purpose: The purpose of this work is to develop and demonstrate a set of practical metrics for CT systems optimization. These metrics, based on the Hotelling observer (HO) figure of merit, are task-based. The authors therefore take the specific example of optimizing a dedicated breast CT system, including the reconstruction algorithm, for two relevant tasks, signal detection and Rayleigh discrimination. Methods: A dedicated breast CT system is simulated using specifications in the literature from an existing prototype. The authors optimize configuration and image reconstruction algorithm parameters for two tasks: the detection of simulated microcalcifications and the discrimination of two adjacent, high-contrast signals, known as the Rayleigh discrimination task. The effects on task performance of breast diameter, signal location, image grid size, projection view number, and reconstruction filter were all investigated. Two HO metrics were evaluated: the percentage of correct decisions in a two-alternative forced choice experiment (equivalent to area under the ROC curve or AUC), and the HO efficiency, defined as the squared ratio of HO signal-to-noise ratio (SNR) in the reconstructed image to HO SNR in the projection data. Results: The ease and efficiency of the HO metric computation allows a rapid high-resolution survey of many system parameters. Optimization of a range of system parameters using the HO results in images that subjectively appear optimal for the tasks investigated. Further, the results of assessment through the HO reproduce closely many existing results in the literature regarding the impact of parameter selection on image quality. Conclusions: This study demonstrates the utility of a task-based approach to system design, evaluation, and optimization. The methodology presented is equally applicable to determining the impact of a wide range of factors, including patient parameters, system and acquisition design, and the reconstruction algorithm. The results demonstrate the versatility of the proposed HO formalism by not only generating a set of parameters that are optimal for a given task but also by qualitatively reproducing many existing results from the breast CT literature. Meanwhile, the implementation of the proposed methodology is straightforward and entirely simulation-based. This is an attractive feature for many system optimization problems, where the goal is to analyze the individual system components such as the image reconstruction algorithm. Final assessment of the system as a whole should be based also on real data studies.