cssi/SciSciGPT-SciSciNet huggingface dataset:
Robust Allocations with Diversity Constraints

We consider the problem of allocating divisible items among multiple agents, and consider the setting where any agent is allowed to introduce diversity constraints on the items they are allocated. We motivate this via settings where the items themselves correspond to user ad slots or task workers with attributes such as race and gender on which the principal seeks to achieve demographic parity. We consider the following question: When an agent expresses diversity constraints into an allocation rule, is the allocation of other agents hurt significantly? If this happens, the cost of introducing such constraints is disproportionately borne by agents who do not benefit from diversity. We codify this via two desiderata capturing robustness. These are no negative externality -- other agents are not hurt -- and monotonicity -- the agent enforcing the constraint does not see a large increase in value. We show in a formal sense that the Nash Welfare rule that maximizes product of agent values is uniquely positioned to be robust when diversity constraints are introduced, while almost all other natural allocation rules fail this criterion. We also show that the guarantees achieved by Nash Welfare are nearly optimal within a widely studied class of allocation rules. We finally perform an empirical simulation on real-world data that models ad allocations to show that this gap between Nash Welfare and other rules persists in the wild.
Neuromorphic Algorithm-hardware Codesign for Temporal Pattern Learning

Neuromorphic computing and spiking neural networks (SNN) mimic the behavior of biological systems and have drawn interest for their potential to perform cognitive tasks with high energy efficiency. However, some factors such as temporal dynamics and spike timings prove critical for information processing but are often ignored by existing works, limiting the performance and applications of neuromorphic computing. On one hand, due to the lack of effective SNN training algorithms, it is difficult to utilize the temporal neural dynamics. Many existing algorithms still treat neuron activation statistically. On the other hand, utilizing temporal neural dynamics also poses challenges to hardware design. Synapses exhibit temporal dynamics, serving as memory units that hold historical information, but are often simplified as a connection with weight. Most current models integrate synaptic activations in some storage medium to represent membrane potential and institute a hard reset of membrane potential after the neuron emits a spike. This is done for its simplicity in hardware, requiring only a “clear” signal to wipe the storage medium, but destroys temporal information stored in the neuron.In this work, we derive an efficient training algorithm for Leaky Integrate and Fire neurons, which is capable of training a SNN to learn complex spatial temporal patterns. We achieved competitive accuracy on two complex datasets. We also demonstrate the advantage of our model by a novel temporal pattern association task. Codesigned with this algorithm, we have developed a CMOS circuit implementation for a memristor-based network of neuron and synapses which retains critical neural dynamics with reduced complexity. This circuit implementation of the neuron model is simulated to demonstrate its ability to react to temporal spiking patterns with an adaptive threshold.
Making Heads and Tails of Models with Marginal Calibration for Sparse Tagsets

For interpreting the behavior of a probabilistic model, it is useful to measure a model’s calibration—the extent to which it produces reliable confidence scores. We address the open problem of calibration for tagging models with sparse tagsets, and recommend strategies to measure and reduce calibration error (CE) in such models. We show that several post-hoc recalibration techniques all reduce calibration error across the marginal distribution for two existing sequence taggers. Moreover, we propose tag frequency grouping (TFG) as a way to measure calibration error in different frequency bands. Further, recalibrating each group separately promotes a more equitable reduction of calibration error across the tag frequency spectrum.
Risk Bounds for Over-parameterized Maximum Margin Classification on Sub-Gaussian Mixtures

Modern machine learning systems such as deep neural networks are often highly over-parameterized so that they can fit the noisy training data exactly, yet they can still achieve small test errors in practice. In this paper, we study this "benign overfitting" (Bartlett et al. (2020)) phenomenon of the maximum margin classifier for linear classification problems. Specifically, we consider data generated from sub-Gaussian mixtures, and provide a tight risk bound for the maximum margin linear classifier in the over-parameterized setting. Our results precisely characterize the condition under which benign overfitting can occur in linear classification problems, and improve on previous work. They also have direct implications for over-parameterized logistic regression.
Distributed Reinforcement Learning for Decentralized Linear Quadratic Control: A Derivative-Free Policy Optimization Approach

This paper considers a distributed reinforcement learning problem for decentralized linear quadratic control with partial state observations and local costs. We propose a Zero-Order Distributed Policy Optimization algorithm (ZODPO) that learns linear local controllers in a distributed fashion, leveraging the ideas of policy gradient, zero-order optimization and consensus algorithms. In ZODPO, each agent estimates the global cost by consensus, and then conducts local policy gradient in parallel based on zero-order gradient estimation. ZODPO only requires limited communication and storage even in large-scale systems. Further, we investigate the nonasymptotic performance of ZODPO and show that the sample complexity to approach a stationary point is polynomial with the error tolerance's inverse and the problem dimensions, demonstrating the scalability of ZODPO. We also show that the controllers generated throughout ZODPO are stabilizing controllers with high probability. Lastly, we numerically test ZODPO on multi-zone HVAC systems.
Business cycles, financial conditions, and nonlinearities

This paper proposes a conceptualization of business cycle fluctuations in which the role of financial conditions and nonlinear dynamics are explicitly incorporated. We highlight the role of investment demand in driving economic fluctuations, consider its endogenous dynamic interactions with profitability and aggregate demand levels as well as financial conditions, emphasize that the sources of instability in an economy cannot be associated exclusively with the real or financial sectors, and incorporate the idea that financial conditions are both important sources of instability and possible nonlinear propagators of other sources of instability. We test the propagation mechanisms of such conceptualization using a Bayesian Threshold Vector Autoregression model for the US economy. The results support the characterization of nonlinear dynamics in the transmission of shocks since there is evidence of asymmetric responses of the variables across two different regimes of financial stress, responding more strongly during loose financial conditions.
Statistical learning method for predicting density-matrix based electron dynamics.

We develop a statistical method to learn a molecular Hamiltonian matrix from a time-series of electron density matrices. We extend our previous method to larger molecular systems by incorporating physical properties to reduce dimensionality, while also exploiting regularization techniques like ridge regression for addressing multicollinearity. With the learned Hamiltonian we can solve the Time-Dependent Hartree-Fock (TDHF) equation to propagate the electron density in time, and predict its dynamics for field-free and field-on scenarios. We observe close quantitative agreement between the predicted dynamics and ground truth for both field-off trajectories similar to the training data, and field-on trajectories outside of the training data.
On Fair and Efficient Allocations of Indivisible Public Goods.

We study fair allocation of indivisible public goods subject to cardinality (budget) constraints. In this model, we have n agents and m available public goods, and we want to select $k \leq m$ goods in a fair and efficient manner. We first establish fundamental connections between the models of private goods, public goods, and public decision making by presenting polynomial-time reductions for the popular solution concepts of maximum Nash welfare (MNW) and leximin. These mechanisms are known to provide remarkable fairness and efficiency guarantees in private goods and public decision making settings. We show that they retain these desirable properties even in the public goods case. We prove that MNW allocations provide fairness guarantees of Proportionality up to one good (Prop1), $1/n$ approximation to Round Robin Share (RRS), and the efficiency guarantee of Pareto Optimality (PO). Further, we show that the problems of finding MNW or leximin-optimal allocations are NP-hard, even in the case of constantly many agents, or binary valuations. This is in sharp contrast to the private goods setting that admits polynomial-time algorithms under binary valuations. We also design pseudo-polynomial time algorithms for computing an exact MNW or leximin-optimal allocation for the cases of (i) constantly many agents, and (ii) constantly many goods with additive valuations. We also present an O(n)-factor approximation algorithm for MNW which also satisfies RRS, Prop1, and 1/2-Prop.
A monolithic 250 GHz Schottky-diode receiver

A 250 GHz monolithic Schottky-diode receiver based on a double-slot antenna is presented. The double-slot antenna is placed on an extended hemispherical high-resistivity silicon substrate lens. The measured DSB conversion loss and noise temperature at 258 GHz are 9.0/spl plusmn/0.3 dB and 2000/spl plusmn/100 K for the antenna/mixer, respectively. The measured results are expected to be about 2 dB better with more LO power and a matching cap layer. The uniplanar double-slot antenna receiver is less than 0.3/spl times/1 mm in size including the IF filter and represents the first fully monolithic 250 GHz receiver to date. >
Chapter 4 Absorption, circular dichroism and optical rotatory dispersion of polypeptides, proteins, prosthetic groups and biomembranes

Publisher Summary The physical methods of absorption, circular dichroism (CD), and optical rotatory dispersion (ORD) are invaluable laboratory tools that are useful at every degree of familiarity with the method. The physical processes of absorption, refraction, circular dichroism, and optical rotatory dispersion are closely inter-related, such that mechanistic discussions of the latter two require adequate consideration of the former two. The chapter begins with consideration of basic elements and terminologies of absorption and refraction, and then treats circular dichroism and optical rotatory dispersion, and in doing so, provides prosthetic group examples of excitation resonance interaction and of the dispersion force interactions giving rise to hyper- and hypochromism in absorption and to reciprocal relations in optical rotation. In addition, the chapter also presents characteristic absorption and circular dichroism spectra of some five or more regular protein and polypeptide conformations. Finally, the chapter reviews the particular problem of applying these methods to the timely study of biomembrane is presented by considering the model poly-L-glutamic acid particulate system and by applying the analysis to the purple membrane of Halobacterium halobium .
Designing and implementing a project evaluation plan

Engineering faculty members involved in education research and development efforts are being asked to provide evidence that their projects are effective and successful. This workshop provides an introduction to and a framework for designing and implementing an evaluation plan to assess these efforts. Through a set of interactive activities, participants will explore a series of issues that emphasize (1) the development of guiding questions; (2) the alignment of the evaluation to the project goals and objectives; (3) the selection of methods and the need for systematic data collection, analysis, and interpretation; and (4) the need to anticipate and address alternative hypotheses and interpretations of the results. With this background, each participant will design an evaluation plan for a project of his or her choice, submit the plan for critique by a subset of participants, and provide and receive constructive feedback. At the end of the workshop, participants should be able to work with an evaluator to develop and carry out an effective evaluation of an engineering education project.
A lower bound on the size of decomposable negation normal form

We consider in this paper the size of a Decomposable Negation Normal Form (DNNF) that respects a given vtree (known as structured DNNF). This representation of propositional knowledge bases was introduced recently and shown to include OBDD as a special case (an OBDD variable ordering is a special type of vtree). We provide a lower bound on the size of any structured DNNF and discuss three particular instances of this bound, which correspond to three distinct subsets of structured DNNF (including OBDD). We show that our lower bound subsumes the influential Sieling and Wegener's lower bound for OBDDs, which is typically used for identifying variable orderings that will cause a blowup in the OBDD size. We show that our lower bound allows for similar usage but with respect to vtrees, which provide structure for DNNFs in the same way that variable orderings provide structure for OBDDs. We finally discuss some of the theoretical and practical implications of our lower bound.
Selenate and selenite sorption on iron oxides : An infrared and electrophoretic study

The authors studied selenate and selenite sorption by amorphous Fe oxide [am-Fe(OH){sub 3}] and goethite ({alpha}-feOOH) as a function of time, pH, ionic strength, and total Se concentration. They examined sorbed selenate and selenite by in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, and electrophoresis to deduce sorption mechanisms. Sorption of both selenate and selenite reached equilibrium in <25 min and the sorption isotherm was not reversible. Increasing ionic strength decreased selenate sorption but did not affect selenite sorption. The presence of either selenate or selenite lowered the electrophoretic mobility (EM) and decreased the point of zero charge (PZC) of both sorbents, suggesting inner-sphere complexation for both selenate and selenite species. Both in situ ATR-FTIR and DRIFT difference spectra showed bidentate complexes of selenate with am-Fe(OH){sub 3}. The structure of selenite complexes in am-Fe(OH){sub 3}-solution interface was uncertain due to insensitivity of the in situ ATR-FTIR technique. The DRIFT spectra of selenite on am-Fe(OH){sub 3} showed {nu}{sub 3} splitting as evidence of complexation. The DRIFT spectra of selenite on goethite showed bridging bidentate complex of selenite. The authors conclude that the influence of ionic strength on Se sorption cannot be usedmore » as a criterion for distinguishing outer- vs. inner-sphere complex formation.« less
On sub‐Riemannian geodesics on the Engel groups: Hamilton's equations

We study the sub-Riemannian geometry on the Engel group which is a step 3 nilpotent Lie group on . Our main result is to solve the Hamiltonian equations associated with the bi-characteristic curves and express the solutions in terms of elliptic functions. Our model covers both the Heisenberg group and the Martinet case when setting certain parameters to be zero.
Current progress in tissue engineering of heart valves: multiscale problems, multiscale solutions

Introduction: Heart valve disease is an increasingly prevalent and clinically serious condition. There are no clinically effective biological diagnostics or treatment strategies. The only recourse available is replacement with a prosthetic valve, but the inability of these devices to grow or respond biologically to their environments necessitates multiple resizing surgeries and life-long coagulation treatment, especially in children. Tissue engineering has a unique opportunity to impact heart valve disease by providing a living valve conduit, capable of growth and biological integration.Areas covered: This review will cover current tissue engineering strategies in fabricating heart valves and their progress towards the clinic, including molded scaffolds using naturally derived or synthetic polymers, decellularization, electrospinning, 3D bioprinting, hybrid techniques, and in vivo engineering.Expert opinion: Whereas much progress has been made to create functional living heart valves, a clinically viable ...
Anti-inflammatory Medication Adherence and Cost and Utilization of Asthma Care in a Commercially Insured Population

Objective. The authors hypothesized that adherence to anti-inflammatory treatment could reduce overall cost of asthma care, as higher spending on drugs would be offset by reductions in hospital and emergency care. Methods. A retrospective observational study using 2 years of claims data for 41,234 commercially insured asthmatics on monotherapy with either leukotriene inhibitors (LI) or inhaled corticosteriods (ICS). Patients were grouped into adherence quartiles based on the percentage of days per year they had prescriptions filled (medication possession ratio). The relationship between adherence and four outcomes was examined: () emergency department (ED) visits, () hospitalizations, () nondrug net payments for asthma care, () total net payments for asthma care (including drug costs). Multivariate and logistic regression models adjusting for demographics, comorbidities, and measures of past asthma utilization were used. Results. Adherence rates were low with a median medication possession ratio of 39% fo...
Lipid metabolism in bone and bone cells I. The in vitro incorporation of [14C]glycerol and [14C]glucose into lipids of bone and bone cell cultures

Abstract 1. 1. To study lipid synthesis in mineralizing tissues, calvaria of new-born rats were incubated in buffer containing radioactive glycerol or glucose. The effects of non-labeled ATP, CTP, and glucose on lipid synthesis were investigated. Lipid synthesis by bone cells grown in primary cell culture was also studied. 2. 2. Calvaria and bone cells were found to contain cholesterol, cholesterol esters, mono-, di- and triglycerides, free fatty acids, and various phospholipids. The phospholipids included lecithin, lysolecithin, phosphatidyl ethanolamine, lysophosphatidyl ethanolamine, phosphatidyl serine, phosphatidyl inositol, cardiolipin, sphingomyelin, and various unidentified components. Appreciable quantities of phosphatidyl serine were not extractable from calvaria until after demineralization with EDTA. 3. 3. The incubation of calvaria or bone cell cultures with [14C]glycerol and [14C]glucose gave rise to lipids labeled in the glycerol moiety of the various glycerides. Triglycerides and lecithin were the two most heavily labeled lipids. Phosphatidyl serine, cholesterol, sphingomyelin, and fatty acids were not labeled with these two labeled precursors. ATP generally stimulated neutral lipid synthesis but retarded phosphohpid synthesis from [14C]glycerol in a medium containing a low level of unlabeled glucose. An elevated glucose level generally decreased labeling of lipids from [14C]glycerol, probably by increasing intracellular glycerol phosphate concentrations. At higher levels of ATP and non-radioactive glucose, varied results were obtained which suggest that critical levels of both substances are required for optimal lipogenesis. CTP stimulated the synthesis of diglycerides, triglycerides, and lecithin, but inhibited the labeling of phosphatidyl ethanolamine. The synthesis of lipid from [14C]glucose was generally inhibited by ATP, but the simple effect of ATP on phosphofructokinase does not totally account for this inhibition.
AUTORADIOGRAPHIC STUDIES OF INTRAMEDULLARY SCHWANN CELLS IN IRRADIATED SPINAL CORDS OF IMMATURE RATS.

This investigation examined the development of intramedullary Schwann cells. The presence of these cells in spinal cords of rats irradiated when three days old and examined 15 or more days later had been noted previously in this laboratory. The present study is an autoradiographic evaluation of spinal cords from groups of rats receiving a single injection of tritiated thymidine at an interval from 7 to 15 days after irradiation (3 days of age) and killed four hours to seven days following injection. The earliest post-irradiation interval at which the intramedullary Schwann cells were present was at nine days in only one animal. These cells were seen in approximately half of the rats injected and killed 11 days after irradiation and in all in the 15-day-group. In all of these cases the animals were killed four hours after injection of tritiated thymidine and a portion of this cell population was labeled. When the time between injection and autopsy was delayed for three or seven days, a decrease in intensity of the labeling was apparent and many cells were lightly labeled, indicating that cell proliferation had occurred. Although the evidence was not conclusive, the results suggested that the intramedullary Schwann cells were probably progeny of cells derived from the dorsal roots, the latter cells having been stimulated to migrate into and to divide within the spinal cord.
Surgical Fires in Laser Laryngeal Surgery: Are We Safe Enough?

ObjectiveLaser surgery of the larynx and airway remains high risk for the formation of operating room fire. Traditional methods of fire prevention have included use of “laser safe” tubes, inflation of a protective cuff with saline, and wet pledgets to protect the endotracheal tube from laser strikes. We tested a mechanical model of laser laryngeal surgery to evaluate the fire risk.Study DesignMechanical model.SettingLaboratory.Subjects and MethodsAn intubation mannequin was positioned for suspension microlaryngoscopy. A Laser-Shield II cuffed endotracheal tube was placed through the larynx and the cuff inflated using saline. Wet pledgets covered the inflated cuff. A CO2 laser created an inadvertent cuff strike at varying oxygen concentrations. Risk reduction measures were implemented to discern any notable change in the outcome after fire.ResultsAt 100% FiO2 an immediate fire with sustained flame was created and at 40% FiO2 a near immediate sustained flame was created. At 29% FiO2, a small nonsustained fl...
Monitoring technology trends with podcasts, RSS and Twitter

Purpose – This paper describes how information professionals can keep up with current technology news by incorporating podcasts, RSS feed readers, and the social messaging service Twitter into their daily routines.Design/methodology/approach – A general review of technologies and news sources.Findings – The rapid pace of technology innovation requires librarians to look for simple ways to monitor new trends that may affect library services. Podcasts, RSS readers and messaging networks like Twitter each represent low‐threshold tools that can serve as resources for breaking news, reviews, and technology journalism.Originality/value – The tools offered in this article provide simple strategies for information professionals to stay abreast of technology innovations as the revelations first emerge. Provides descriptions of technologies and reviews several technology podcasts, blogs, and journalists worth following.
The Design And Performance Of A Moderate Price, Research Grade FT-IR Spectrometer

This paper describes the design of the Digilab FTS 60 FT-IR spectrometer. Aspects of both the optical bench and the computer system are shown. The FTS 60 is characterised by high throughput, compact size, versatility and a powerful data system, based on the Motorola 68000 microprocessor.
Phase separation of binary fluids in porous media: Asymmetries in pore geometry and fluid composition.

Phase separation of a binary Lennard-Jones fluid confined in a variety of two-dimensional pores is studied using molecular dynamics simluations. We consider a simple strip pore, an uneven single pore, and a junction made out of two pores. We have studied dynamics of phase separation for both critical and off-critical composition of the binary fluid. We find the existence of long-lived metastable states in the presence of asymmetries both in the geometry and the composition of the fluid. The results are compared with theoretical predictions and with experimental observations.
Fine structure of the sperm of the lovebug, Plecia Nearctica hardy (Diptera: Bibionidae)

Abstract The sperm of the lovebug, Plecia nearctica possesses an acrosome, which caps the apical and anterior lateral surfaces of a spear-shaped nucleus, which has parallel, bilateral concavities running throughout its length. At the junction of the nucleus and axial filament, a centriole adjunct has developed. An extension of this complex extends along one side of the sperm tail, partially surrounding the nebenkern and axial filament. A single nebenkern is found parallel with the axial filament along most of its length. A 9 + 0 tubule pattern exists in the axial filament with the central pair of tubules being replaced by a prominent central sheath.
Development of a golden beam data set for the commissioning of a proton double-scattering system in a pencil-beam dose calculation algorithm

Purpose: The purpose of this investigation is to determine if a single set of beam data, described by a minimal set of equations and fitting variables, can be used to commission different installations of a proton double-scattering system in a commercial pencil-beam dose calculation algorithm. Methods: The beam model parameters required to commission the pencil-beam dose calculation algorithm (virtual and effective SAD, effective source size, and pristine-peak energy spread) are determined for a commercial double-scattering system. These parameters are measured in a first room and parameterized as function of proton energy and nozzle settings by fitting four analytical equations to the measured data. The combination of these equations and fitting values constitutes the golden beam data (GBD). To determine the variation in dose delivery between installations, the same dosimetric properties are measured in two additional rooms at the same facility, as well as in a single room at another facility. The difference between the room-specific measurements and the GBD is evaluated against tolerances that guarantee the 3D dose distribution in each of the rooms matches the GBD-based dose distribution within clinically reasonable limits. The pencil-beam treatment-planning algorithm is commissioned with the GBD. The three-dimensional dose distribution in water is evaluated in the four treatment rooms and compared to the treatment-planning calculated dose distribution. Results: The virtual and effective SAD measurements fall between 226 and 257 cm. The effective source size varies between 2.4 and 6.2 cm for the large-field options, and 1.0 and 2.0 cm for the small-field options. The pristine-peak energy spread decreases from 1.05% at the lowest range to 0.6% at the highest. The virtual SAD as well as the effective source size can be accurately described by a linear relationship as function of the inverse of the residual energy. An additional linear correction term as function of RM-step thickness is required for accurate parameterization of the effective SAD. The GBD energy spread is given by a linear function of the exponential of the beam energy. Except for a few outliers, the measured parameters match the GBD within the specified tolerances in all of the four rooms investigated. For a SOBP field with a range of 15 g/cm2 and an air gap of 25 cm, the maximum difference in the 80%–20% lateral penumbra between the GBD-commissioned treatment-planning system and measurements in any of the four rooms is 0.5 mm. Conclusions: The beam model parameters of the double-scattering system can be parameterized with a limited set of equations and parameters. This GBD closely matches the measured dosimetric properties in four different rooms.
Effect of four antimicrobials against an Encephalitozoon sp. (Microsporidia) in a grasshopper host.

Abstract Encephalitozoon spp. are the primary microsporidial pathogens of humans and domesticated animals. In this experiment, we test the efficacy of 4 commercial antimicrobials against an Encephalitozoon sp. infecting a grasshopper (Romalea microptera) host. Oral treatment with fumagillin or thiabendazole significantly reduced pathogen spore counts (93% and 88% respectively), whereas spore counts of grasshoppers fed quinine produced a non-significant 53% reduction in spores, and those fed streptomycin a non-significant 29% increase in spores, compared to the control. We observed a moderate dose–response effect for thiabendazole, whereby spore count decreased as drug consumption increased. No thiabendazole-treated animals died, whereas 27% of streptomycin-treated animals died, suggesting that thiabendazole was not toxic at the doses administered. The deaths among streptomycin-treated animals may have been caused by drug toxicity, parasite burden, or both. Although fumagillin and thiabendazole significantly reduced spore counts, in no individual was the pathogen totally eliminated. Our data confirm that microsporidia are difficult to control and that fumagillin and thiabendazole are partially effective antimicrobials against this group. Our study suggests that quinine and related alkaloids should be further examined for antimicrosporidial activity, and streptomycin should be examined as a possible enhancer of microsporidiosis.
GROUND-WATER PROCESSES CONTROLLING A PRAIRIE LAKE'S RESPONSE TO MIDDLE HOLOCENE DROUGHT

Lake response to climate forcing is commonly regarded as being controlled by within-lake processes. We present a case from the northern Great Plains in which Holocene drought response recorded in lake sediments was determined by changes in chemical characteristics of source ground water. Middle Holocene ostracode assemblages were dominated by halophylic Limnocythere staplini , indicating increased lake-water salinity, yet the oxygen isotope values in this period decreased by 2‰ to 3‰, contrary to expectations of evaporative dominance. We infer from these proxy records and ground-water flow-model results that the paleoclimatic record in the lake was mediated by changes in ground-water catchment area and by reduction in evapotranspiration accompanying desiccation of peripheral lake basins.
Stability of extemporaneously prepared acetylcysteine 1% and 10% solutions for treatment of meconium ileus.

Purpose The stability of extemporaneously prepared acetylcysteine 1% and 10% solutions for treatment of meconium ileus was evaluated. Methods Acetylcysteine 1% (10-mg/mL) and 10% (100-mg/mL) solutions were prepared by mixing 3 and 10 mL, respectively, of commercially available 20% acetylcysteine solution with a sufficient quantity of bacteriostatic 0.9% sodium chloride for injection to make a final volume of 60 mL. Three identical samples of each concentration were prepared, placed in 2-oz amber plastic prescription bottles, and stored at 20–25 °C. Samples were assayed in duplicate using high-performance liquid chromatography and inspected for changes in color, odor, and pH immediately after preparation and at 7, 14, 30, 60, and 90 days. Stability was defined as retention of at least 90% of the initial concentration. Results At least 90% of the initial concentration of acetylcysteine was retained in both formulations for 60 days. No appreciable change from the initial pH occurred in the acetylcysteine 1% or 10% solution during the first 60 days, but there was a notable change in pH after 90 days in both formulations. Neither solution was stable at day 90. There was no detectable change in color at 90 days; however, the odor of hydrogen sulfide was more pungent than on previous study days. Conclusion Extemporaneously prepared solutions of acetylcysteine 1% (10 mg/mL) and 10% (100 mg/mL) prepared with bacteriostatic 0.9% sodium chloride for injection were stable for at least 60 days when stored in plastic amber bottles at room temperature.
The Impact of Nonlinear Dynamics in the Atmospheric Sciences

In this review some of the achievements in atmospheric sciences that resulted from chaos theory and its implications are discussed. They include El Nino dynamics, physics and spatiotemporal dynamics of the general circulation, and ensemble forecasting.
Electronic structure of ordered silicon alloys: Direct-gap systems.

Density functional theory (within the local density approximation) is applied to minimize the total energy of a set of Si/(group IV) ordered alloys and to calculate the associated electronic band structures. A series of fully relaxed Si/Sn alloys show direct gaps when constructed on the (100) surface of silicon in cubic-based superlattices, with the band gap of the Si/Sn alloys decreasing nearly linearly with increased atomic Sn fraction. Equivalent calculations performed with Ge and C substitutions are predicted to have direct and indirect gaps, respectively. Ternary alloys of Si/Ge/Sn and Si/Ge/C have band-structure features dominated by either the Sn or C substitutions having band gaps of the respective binary alloys. The magnitude of the conduction-band curvature (the effective mass) at the zone center of these alloys shows a strong variation dependent on the particular substitution. Energy barriers of the minor constituents are computed to estimate the stability of the binary alloys with resulting barriers near 0.25 eV for Sn and Ge atoms in a silicon matrix. \textcopyright{} 1996 The American Physical Society.
Mother-infant antidepressant concentrations, maternal depression, and perinatal events.

Objective The authors explored the relationship of cord-maternal antidepressant concentration ratios and maternal depression with perinatal events and preterm birth. Method The investigators examined 21 mother-infant pairs that had antidepressant exposure during pregnancy. The antidepressants included serotonin reuptake inhibitors (SRIs) and nortriptyline (a norepinephrine inhibitor and mild SRI). The mothers were evaluated with the Structured Clinical Interview for DSM-IV. Depression ratings were repeated at 20, 30, and 36 weeks' pregnancy. At delivery, investigators assessed cord and maternal antidepressant concentrations, neonatal outcomes on the Peripartum Events Scale (PES), and gestational weeks at birth. The investigators performed this study at the Women's Behavioral HealthCARE Program, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pennsylvania, from April 2003 until September 2006. Results Mean ± SD cord-to-maternal concentration ratios were 0.52 ± 0.35 (range, 0.00-1.64) for the parent drug and 0.54 ± 0.17 (range, 0.28-0.79) for the metabolite. Nine of 21 mothers (43%) had a major depressive episode. From examining the maximum depression ratings, the mean ± SD Structured Interview Guide for the Hamilton Depression Rating Scale, Atypical Depression Symptoms Version score was 16.0 ± 7.6. One third (7/21) of infants had at least 1 perinatal event (PES ≥ 1). The frequency of deliveries complicated by any perinatal event was similar in depressed and nondepressed mothers. There was no significant association between perinatal events and cord-to-maternal antidepressant concentration ratios or maternal depression levels. Exposure to short half-life antidepressants compared to fluoxetine resulted in more perinatal events (7/16 = 44% vs 0/5 = 0%; P = .06). Fourteen percent (3/21) of infants were preterm. Preterm birth was not associated with cord-to-maternal metabolite concentration ratios, depression levels, or exposure to fluoxetine. Conclusions Antidepressant-exposed infants experienced a limited number of transient perinatal events. No association between cord-maternal concentration ratios or maternal depression and perinatal events could be identified. Contrary to other reports, we detected no increased risk for perinatal events with fluoxetine therapy compared to the short half-life antidepressants. Trial registration clinicaltrials.gov Identifier: NCT00279370.
Domain organization of RNA polymerase α subunit: C-terminal 85 amino acids constitute a domain capable of dimerization and DNA binding

Summary Using limited proteolysis, we show that the Escherichia coli RNA polymerase α subunit consists of an N-terminal domain comprised of amino acids 8241, a C-terminal domain comprised of amino acids 249329, and an unstructured and/or flexible interdomain linker. We have carried out a detailed structural and functional analysis of an 85 amino acid proteolytic fragment corresponding to the C-terminal domain (αCTD-2). Our results establish that αCTD-2 has a defined secondary structure (∼40% α helix, ∼0% β sheet). Our results further establish that αCTD-2 is a dimer and that αCTD-2 exhibits sequence-specific DNA binding activity. Our results suggest a model for the mechanism of involvement of α in transcription activation by promoter upstream elements and upstream-binding activator proteins.
Copolymers of rac-Lactide and ε -Caprolactone: Conventional Copolymerization vs. Macroinitiator Copolymerization

Copolymers of rac-lactide (rac-LA) and e -caprolactone (CL) were synthesized with tin(II) 2-ethylhexanoate and 1,4-butanediol at 130°C using two methods of copolymerization: conventional copolymerization and sequential polymerization using poly(CL) as a macroinitiator for rac-LA. Conventional copolymerizations showed a retarded rate of CL conversion until rac-LA reached high conversion. The macroinitiator method led to reduced overall reaction time to reach high conversion of both monomers. At a low CL comonomer ratio, the copolymers synthesized by the two different methods were very similar but, as the comonomer ratio was increased, differences in monomer sequencing (e.g. random vs. blocky) as determined by 13C-NMR and glass transition were observed. Additionally, macroinitiator synthesis carried out at 150°C in an effort to promote transesterification did not show any significant differences from the copolymer synthesized at 130°C.
Diabatic-state treatment of negative-meson moderation and capture. I. The hydrogen atom

A new formulation of the moderation and capture of negative mesons by atoms has been developed. The scattering is described by a complex potential with a real part given by a diabatic interaction potential and an imaginary part given by the ionization width of the diabatic state embedded in the electronic continuum. Results are presented for collisions of ${\ensuremath{\mu}}^{\ensuremath{-}}$, ${\ensuremath{\pi}}^{\ensuremath{-}}$, ${K}^{\ensuremath{-}}$, and ${p}^{\ensuremath{-}}$ with the hydrogen atom. The differential energy-loss cross sections and stopping powers obtained are large. The energy spectrum of stopped mesons is determined and most captures are found to occur at collision energies below or near the ionization potential. The principal-quantum-number distributions of the initially formed mesic atoms peak close to the orbital giving optimal overlap with the displaced electronic orbital. The angular-momentum distributions are not too different from statistical, except that they tend to cut off at $l$ significantly smaller than $n\ensuremath{-}1$ in the case of large $n$. Comparison to a very recent experiment is made in a note added.
Effective Lagrangians and SU(3) × SU(3) Symmetry Breaking

At last year’s Schladming Winter School, Professor Gursey discussed some aspects of the effective Lagrangian technique, which he helped to develop [1]. In the following lectures I shall apply this technique to the study of chiral SU(3) × SU(3). As background to a detailed discussion of a model Lagrangian, I will (i) review the Lagrangian formalism, (ii) discuss the transformation properties of fields, (iii) show how field algebra and symmetry breaking that leads to PCAC are implemented. In the discussion of the model, which was worked out in collaboration with D. A. Geffen, I will lay stress on the leptonic decay constants of the spin O and spin 1 mesons, as far as comparison with experiment is concerned. For the rest, the stress will be on the technical aspects of constructing effective Lagrangians. Baryons will not be discussed, except of a brief mention in sec. (II) [2].
The seasonal effect of nitric oxide cooling on the thermospheric U.V. heat budget

The effects of (1) the radiative cooling of vibrationally-excited NO at 5.3 microns and (2) radiation entrapment at 63 microns on the UV heating efficiency 'epsilon' are examined. It is noted that the previously used heating efficiency definition contradicts its logical application, and that the two processes mentioned should be included as cooling phenomena in the energy equations. Comparisons are made with previous work by including O and NO radiative cooling in the calculation of epsilon, which is found to vary from 45 to 60%, depending on how the two radiative cooling mechanisms are included in the calculation. It is also found that the shape of the heating efficiency altitude profile varies with season, while the peak value is nearly invariant.
The level scheme of 171Tm

Abstract The gamma-ray spectrum associated with the decay of 171 Er has been studied with curved-crystal and Ge(Li) spectrometers. The data provide energy and intensity measurements of 40 gamma rays. A previously unreported weak 694 keV transition which appears to belong to the decay of 171 Er has been measured. Previously reported transitions at 166, 404, 573 and 842 keV have not been observed. Coincidence spectra show that the 372 keV transition feeds the 913 keV level. The absence of transitions at 166 keV and 404 keV together with the new placement of the 372 keV transition place the existence of a previously proposed 591 keV level in doubt. A recently proposed level at 489 keV is not supported by the energy measurements and coincidence data of the present study. The new placement of the 372 keV transition suggests a new level at 1285 keV.
Design considerations for the LCLS

The Linac Coherent Light Source (LCLS) is a single pass X-ray FEL designed to produce very short (∼200 fs) and very high power (8 GW), short wavelength (1.5 A) pulses. The new facility to be built at SLAC as a multiple laboratory collaboration will have peak brilliance performance exceeding those obtained presently in third generation synchrotron radiation sources by 10 orders of magnitude. In this paper, we review the accelerator physics design challenges. We report on advances made in photo-injectors. We discuss the issues of Coherent Synchrotron Radiation produced in the bunch compressors and undulator vacuum chamber wakefields.
EXPERIMENTS ON PHOTOPERIOD IN RELATION TO THE VEGETATIVE GROWTH OF PLANTS.

It has long been known that relative length of day and night effects the vegetative as well as the reproductive activity of plants. Since the appearance of the paper of Garner and Allard (7) which first dealt with this subject, abundant factual material has accumulated relating to the influence of photoperiod on such varied processes as shoot elongation, leaf size, accumulation of dry weight and root growth (6, 10). It has been frequently, although not invariably, found that vegetative growth as measured by one or more of these criteria, is greater in long days than in short days irrespective of the reproductive behavior of the species in question. The promotive effect of long daily photoperiods on vegetative growth does not appear to be directly attributable to increased duration of C02 assimilation (11). Plants grown under conditions of long day made up of a short photoperiod of natural light supplemented by light of exceedingly low intensity exhibit the vegetative vigor typical of plants on a long day rather than that of plants on a short day regime (13). It is known that the reproductive response of photoperiod sensitive plants is to be attributed to the production of a specific hormone (or hormones) in the leaves under conditions of suitable day length (8, 9). The production of this particular hormone or hormones would appear to depend on the length of day to which the leaves are subjected. It seems logical to inquire in how far the vegetative responses of plants to varying photoperiods are also attributable to the influence of day length on the production of the several hormones which regulate vegetative growth. In the present paper evidence will be presented to show that the production of vitamin Bi, a hormone for the growth of roots (1), is affected by the length of day to which the plant is subjected. It is known that length of day exercises a profound effect on the extent of the root system in many species of plants. Thus Weaver and Himmel (12) found that the root system is invariably more extensive under conditions of long photoperiod irrespective of whether the species of plant is long day, short day, or indeterminate with regard to flowering behavior. Crist and Stout (5) have also shown that the root system of plants grown under short photoperiod may be several times smaller than the root systems of similar plants grown under conditions of long photoperiod. These observa-
Tensor product variable binding and the representation of symbolic structures in connectionist systems

Abstract A general method, the tensor product representation, is defined for the connectionist representation of value/variable bindings. The technique is a formalization of the idea that a set of value/variable pairs can be represented by accumulating activity in a collection of units each of which computes the product of a feature of a variable and a feature of its value. The method allows the fully distributed representation of bindings and symbolic structures. Fully and partially localized special cases of the tensor product representation reduce to existing cases of connectionist representations of structured data. The representation rests on a principled analysis of structure; it saturates gracefully as larger structures are represented; it permits recursive construction of complex representations from simpler ones; it respects the independence of the capacities to generate and maintain multiple bindings in parallel; it extends naturally to continuous structures and continuous representational patterns; it permits values to also serve as variables; and it enables analysis of the interference of symbolic structures stored in associative memories. It has also served as the basis for working connectionist models of high-level cognitive tasks.
The impact of new labeling regulations on the use of voluntary nutrient-content and health claims by food manufacturers

Abstract The authors analyze the impact of the Nutrition Labeling and Education Act on the use of voluntary claims in 19 product categories between 1992 and 1999. The percentage of products that make nutrient-content claims decreased somewhat, and the major effect was a redistribution of claim activity among product categories. Products that make health and healthy claims increased, but these claims remained relatively rare.