cssi/SciSciGPT-SciSciNet huggingface dataset:
Improved Dixon Resultant for Generating Signed Algebraic Level Sets and Algebraic Boolean Operations on Closed Parametric Surfaces

Abstract Complex physical problems with emerging topologies such as phase nucleation and growth during solidification or electromigration, as well as design problems such as topology optimization are commonly modeled using phase field or level set methods. However, the implicit representations of the evolving interfaces in these methods implicitize geometrical parameters such as normals and curvatures that dictate phase evolution, and recover the exact interface geometry only in the limit of mesh refinement. Recently, an explicit interface method termed Enriched Isogeometric Analysis (EIGA) was developed to model physical problems with evolving phases. This method uses signed algebraic level sets generated from the Dixon resultant to capture the influence of the interface on its neighborhood. The signed algebraic level sets allow modeling topological changes through algebraic Boolean operations using R-functions. However, a challenge in generating algebraic level sets from parametric surfaces is that the Dixon resultant fails to implicitize or lacks a sign for common parametric surfaces such as spheres or cylinders. The lack of sign prevents implicit Boolean operations using R-functions to capture topological changes. In this paper, a maximal-rank submatrix approach is used to recover implicitizations of parametric surfaces with trivially singular Dixon resultants. Furthermore, a multivariate polynomial square root method is developed to recover sign from unsigned resultants. The generated signed algebraic level sets are then demonstrated to solve three-dimensional heat conduction in a solid with multiple, arbitrarily-shaped voids. Algebraic Boolean operations using R-functions on these signed level sets are used to naturally capture coalescence of voids without needing surface–surface intersection calculation.
Oligodendrocyte Development and Regenerative Therapeutics in Multiple Sclerosis

Myelination by oligodendrocytes (OLs) is an important biological process essential for central nervous system (CNS) development and functions. Oligodendroglial lineage cells undergo several morphological and molecular changes at different stages of their lineage progression into myelinating OLs. The transition steps of the oligodendrocyte progenitor cells (OPCs) to myelinating oligodendrocytes are defined by a specific pattern of regulated gene expression, which is under the control of coordinated signaling pathways. Any abnormal development, loss or failure of oligodendrocytes to myelinate axons can lead to several neurodegenerative diseases like multiple sclerosis (MS). MS is characterized by inflammation and demyelination, and current treatments target only the immune component of the disease, but have little impact on remyelination. Recently, several pharmacological compounds enhancing remyelination have been identified and some of them are in clinical trials. Here, we will review the current knowledge on oligodendrocyte differentiation, myelination and remyelination. We will focus on MS as a pathological condition, the most common chronic inflammatory demyelinating disease of the CNS in young adults.
A LoRa Based Reliable and Low Power Vehicle to Everything (V2X) Communication Architecture

The industrial development of the last few decades has prompt to increase in the number of vehicles multi-fold. With the increased number of vehicles on the road, safety has become one of the major concerns. Inter vehicular communication, specially Vehicle to Everything (V2X) communication can address these pressing issues including autonomous traffic systems and autonomous driving. Extensive research is going on to develop a reliable V2X communication architecture with different wireless technologies like Long Range (LoRa) communication, Zigbee, LTE, and 5G. The reliability and effectiveness of V2X communication greatly depend on communication architecture and the associated wireless technology. In this conquest, a LoRa based reliable, robust, and low power V2X communication architecture is proposed in this paper. The communication architecture is designed, implemented, and tested in a real world scenario to evaluate its reliability. Testing and analysis suggest a vehicle in the road can communicate reliably with roadside infrastructures at different speeds ranging from (10-30) Miles per Hour (MPH) with the proposed architecture. At 10 MPH, a vehicle sends one data packet of 40 bytes every 27 meters and at 30 MPH, it sends the same data packet every 53 meters with smooth transitioning from communicating with one infrastructure to another.
Novel Cancer Therapeutics and Implications for Rehabilitation

To determine how the more recently developed cancer treatments may impact patient function. To determine how rehabilitation medicine may assist in improving quality of life in cancer survivors being treated with novel cancer therapeutics. Chimeric antigen receptor-T cell therapy, poly adenosine diphosphate-ribose polymerase (PARP) inhibitors, immune checkpoint inhibitors, and cancer-specific vaccines are more recently developed anti-neoplastic treatments that are positively affecting survivorship curves. These treatments come with unique toxicity profiles including pain, neurologic impairment, cognitive impairment, and fatigue which can impact patient function and quality of life. Novel cancer treatments allow for prolonged cancer survivorship with the potential for long-term physical and/or cognitive deficits. Rehabilitation medicine is experiencing an ever-expanding role in managing the functional decline associated with cancer treatments and providing services that improve function and quality of life in cancer survivorship.
In Reply: You Have to Use Endoscopy

Plastic foreign bodies in the trachea may be tricky, as Drs. Stool and Bluestone point out. We would not hesitate to use bronchoscopy on their patient either, since the history, physical examination, and roentgenograms all were equivo cal. Bronchoscopy was diagnostic as well as therapeutic. Postural drainage treatment is not appropriate without a diagnosis of foreign body aspiration. Stool and Bluestone correctly point out the hazard of migration of the foreign body, with the potential complication of glottic obstruction or spasm. See image in the PDF file
Effects of Ultraviolet Radiation on Marine Phytoplankton

Our studies in both the Antarctic and tropical waters, addressed three major questions: (1) To what extent does ultraviolet radiation (UVR) reduce integrated rates of primary production, and what is the action spectrum for such inhibition of photosynthesis?; (2) Is there differential sensitivity to UVR in Antarctic species of phytoplankton, especially in regard to the microplankton, which are the food items preferred by krill?; (3) Are phytoplankton from Antarctic water more sensitive to UVR than phytoplankton from tropical waters, which seasonally receive much more UVR that Antarctic waters?
Normal default theories

A common form of default reasoning involves default rules of the following type: under normal circumstances, if φ then conclude ψ. Such rules allow us to derive ψ from φ unless the situation is not normal, that is, we know facts that contradict ψ. In other words, we conclude ψ if φ is known and ψ is consistent. The intuitive meaning of the rule under normal circumstances, if φ then conclude ψ is captured well by the default $$ \frac{{\varphi :M\psi }}{\psi } $$
Abstract T P350: Phase I Clinical Feasibility &Safety Trial of Remote Ischemic Conditioning After Aneurysmal Subarachnoid Hemorrhage

Objective: Remote ischemic conditioning (RIC) is a phenomenon by which brief periods of sublethal ischemia in one tissue confers protection from ischemia to distant tissues. The safety and feasibility of RIC must be assessed before testing it in efficacy trials. We report a phase I feasibility and safety trial of RIC in aneurysmal subarachnoid hemorrhage (aSAH) patients. Methods: Patients with aSAH received 2-4 RIC sessions on non-consecutive days. A complete session was defined as four rounds of 5 minutes of one sided lower limb ischemia with a thigh blood pressure cuff followed by 5 minutes of reperfusion (verified by pedal Doppler). Primary end-points were tolerance to the procedure and any complication attributable to RIC. Secondary end-points included cerebral infarction or hemorrhage. Results: Twenty-one patients (67% female, mean age 52, Fisher 3.5, H&H 3.3) were enrolled. Seventeen had evidence of vasospasm during hospitalization. Of 76 RIC sessions performed, 75 (98.7%) were completed and tolerated. One session was incomplete due to poor cooperation secondary to delirium. No patients developed DVTs or other local complications within 2 weeks of their final RIC session. No patients suffered cerebral infarction or hemorrhage throughout the duration of RIC sessions and through 72 hours after their last complete session. Three had infarction confirmed on MRI at 3 and 5 days following the final RIC session. In conscious patients, there was a small increase in the analog pain scale upon inflation of the cuff (deflated: 0.5 inflated: 1.2, p<0.0005), but none requested to stop the session. There was no significant change in other vitals. Conclusions: In aSAH patients, RIC was successfully applied and well tolerated with no procedure-related complications. No patient suffered ischemic stroke within 72 hours of RIC, consistent with our previous studies showing protective cerebral metabolic changes up to 48 hours after sessions. These results demonstrate that application of RIC is safe and feasible and suggest that RIC may be associated with transient tolerance to ischemia during the treatment period. The efficacy of RIC for neuroprotection should be investigated in larger controlled trials.
DIESEL PARTICULATE TRAP REGENERATION TECHNIQUES

Diesel engine particulates collected on a trap cause the exhaust back pressure to increase and adversely affect fuel economy and vehicle performance. Therefore, a trap must be periodically regenerated by oxidizing the collected particulates. Several techniques for regenerating a diesel particulate trap are discussed. Regeneration was achieved with high speed and high load engine operation. Lead, added to the diesel fuel, acted as a catalyst and reduced the ignition temperature of particulates collected on a trap by about 300 degree F. Throttling the intake air flow increased exhaust temperature to facilitate regeneration over the widest range of engine operating conditions, including idle.
Attitudes and perspectives of frontline workers in environmental policy: a case study of Ohio's Environmental Protection Agency and Wisconsin's Department of Natural Resources

This research is an effort to focus on frontline regulators with the Ohio Environmental Protection Agency and Wisconsin Department of Natural Resources. An online survey was conducted of frontline regulators in these agencies to explore their knowledge, attitudes, and perspectives on policy implementation. More specifically, we endeavor to answer how frontline workers implement environmental policy. To analyze these data, we use two categorizations of factors (knowledge and attitudes, and contextual factors) offered by May and Winter (2009) to examine what influences the decision making of frontline regulators in their regulatory interactions. We find that despite common presumptions of adversarialism in the environmental regulatory arena, the frontline environmental inspectors in these states generally have positive attitudes of their regulatory colleagues and cope well with external contextual factors. While our findings are exploratory and descriptive, we argue that they are important for the next generation of environmental policy in the USA. Copyright © 2012 John Wiley & Sons, Ltd.
Presheath profiles in simulated tokamak edge plasmas

Abstract Steady state magnetized plasmas produced by the PISCES experiment are used to study plasma-wall interaction phenomena relevant to confinement devices such as tokamaks. An experimental investigation of the presheath region that extends from a wall surface into “simulated tokamak” edge plasmas along magnetic field lines is reported. Diagnostics especially developed for this work include a fast-scanning multiple Langmuir/Emissive/Mach probe system and a CID camera imaging system. Measurements of density, electron temperature, floating potential, space potential, and bulk plasma flow velocities have been obtained in plasmas with densities ranging from 1012 to 1013 cm−3, electron temperatures from 5 to 15 eV. and axial magnetic fields of 0.2 to 1.4 kG. Plasma density profiles along the magnetic field typically show a characteristic factor of 2 decrease towards the wall surface. A plasma potential variation in the near presheath zone of order 0.5 T e is measured, consistent with the bulk plasma flow approaching the ion sound speed near the wall surface, as inferred from a simple “free fall” model. A Boltzmann model for the presheath density profile accuracy tracks the density profile measured both by the Mach probe and by spectroscopic means. Flow profiles are used as a consistency check on various magnetized Mach probe theories. Results suggest that cross-field transport of parallel momentum through viscosity is relatively unimportant in PISCES plasmas and thus may be unimportant in tokamak boundary layer plasmas. Discharges with non-thermal electrons display axial profiles of space potential and floating potential which indicate a “hotter” electron distribution function near the wall surface, consistent with “colder” electrons being reflected by the presheath potential drop.
Drosophila learning and memory revisited

Abstract A newly developed classical conditioning procedure for Drosophila produces strong associative learning and long-lasting memory in wild-type flies. The single-gene mutants amnesiac, rutabaga, turnip and dunce show moderate levels of associative learning and rapid short-term memory losses. Long-term memory formation in these mutants appears normal. The dunce gene has been cloned and most likely encodes a phosphodiesterase, thereby corroborating biochemical evidence that dunce (and rutabaga ) affect an enzymatic component of the cAMP cell-signalling system. In addition, the turnip mutation severely disrupts protein kinase C activity. Thus, a second second-messenger system may be involved in learning and memory in Drosophila .
Design and Control of a Compact and Flexible Pneumatic Artificial Muscle Actuation System: Part Two—Robust Control

A robust control approach is presented in this part of the paper, which provides an effective servo control for the novel PAM actuation system presented in Part I. Control of PAM actuation systems is generally considered as a challenging topic, due primarily to the highly nonlinear nature of such system. With the introduction of new design features (variable-radius pulley and spring-return mechanism), the new PAM actuation system involves additional nonlinearities (e.g. the nonlinear relationship between the joint angle and the actuator length), which further increasing the control difficulty. To address this issue, a nonlinear model based approach is developed. The foundation of this approach is a dynamic model of the new actuation system, which covers the major nonlinear processes in the system, including the load dynamics, force generation from internal pressure, pressure dynamics, and mass flow regulation with servo valve. Based on this nonlinear model, a sliding mode control approach is developed, which provides a robust control of the joint motion in the presence of model uncertainties and disturbances. This control was implemented on an experimental setup, and the effectiveness of the controller demonstrated by sinusoidal tracking at different frequencies.© 2011 ASME
Zonally Symmetric Response to Atmospheric Tidal Forcing in the Dusty Martian Atmosphere

The paper presents a steady state, zonally symmetric response of an atmospheric circulation to the combined effects of the very large zonal-mean diabatic heating and thermotidal forcing thought to exist in the dusty Martian atmosphere during one of its episodic global dust storms. The zonal-mean components of the tidal flux-convergences of momentum and heat are computed using an existing classical atmospheric tidal model constrained by the surface pressure observations at the two Viking Lander sites on Mars. A nearly inviscid two-dimensional model is used to compute the zonally symmetric response to the computed tidal flux-convergences and to the zonal-mean heating of the airborne dust. The results are compared with data from the Viking missions.
Complications in skull base surgery for malignancy.

Objectives: To review a consecutive series of skull base surgeries, establish the rate of complications, and outline their prevention and management. Study Design: A retrospective review of 107 consecutive intracranial/extracranial operations performed for malignancy that transgresses the skull base. Methods: The hospital charts of 107 operations performed on 98 patients at the University of California at Davis Medical Center. The type of operation, cause of death, and complications were noted. Results: The complication rate was 50.5%. Forty-eight patients had no complications. There were six perioperative deaths. The most common surgical complications were cerebrospinal fluid leak (11.2%), meningitis (4.8%), and wound breakdown (15%). The most common medical complications were pneumonia (6.5%), cardiac disturbance (4.7%), and electrolyte imbalance (3.7%). The only prior treatment that was accompanied by a significant increase in complications was previous surgery. Conclusions: Complications occurred in approximately half of the patients who had cranial base surgery for the intracranial spread of head and neck cancer. The perioperative death rate is less than 4%. The major complications were at an acceptable rate.
Recertification. A continuing debate

Abstract Recertification, like taxes, will never draw many supporters from the targeted group. Why should physicians who have had to survive the stiffest of scholastic labors in order to obtain the privilege of a medical education again be asked to prove their continuing worth long after graduation? Apparently because health consumers feel that physicians occupy a critical role and want more tangible evidence that they are keeping up with the explosion of medical knowledge. Dr. Trobe has sought the opinion of Dr. Melvin Rubin, who challenges the assumption that a recertification test will offer a sufficient guarantee of clinical excellence to warrant the expense to the public and the “mental anguish” to physicians, and the opinion of Dr. Sidney Wolfe, who argues that examination is a necessary (though perhaps not sufficient) protection against flagging knowledge and skill.
Expression of Na, K-ATPase alpha and beta isoforms in the neonatal rat cochlea.

The postnatal expression of five Na, K-ATPase alpha (alpha 1, alpha 2, alpha 3) and beta (beta 1, beta 2) subunit isoforms in the rat cochlea was investigated by immunocytochemistry. High levels of expression of the alpha 1 and beta 2 isoforms were observed in stria vascularis (SV) at all developmental stages. alpha 1 and beta 1 isoforms showed a distinct time-dependent developmental expression pattern in tissues of the spiral ligament (SL) and spiral limbus (SLi). Limited, temporary expression of alpha 2 and alpha 3 subunit isoforms were found in SV and SL. Expression of each isoform was also seen in organ of Corti (OC), spiral ganglion (SG), cochlear nerve (CN) and Kolliker's Organ (KO). These observations suggest that individual isoforms may exert specific actions postnatally during final cochlear maturation.
Chronic Lymphocytic Cholangitis in Three Cats

Wedge biopsy of the liver during episodic clinical illness in three male cats showed lymphocytic cholangitis. Principal clinical findings were increased serum alkaline phosphatase activity and hepatomegaly (two cats) associated with anorexia, pyrexia. and weight loss; these signs of illness were intermittent with asymptomatic periods. The hepatic lesions were characterized by lymphoid aggregate or follicle formation, diffusely dispersed lymphocytes and plasma cells, and abnormal bile ducts and ductules. Lymphoid aggregates and diffusely scattered lymphocytes were seen in the pancreas also. The spectrum of hepatic lesions in three cats seemed to represent a progression in the development of the disease. Similarities and dissimilarities between the findings in the three cats and human primary biliary cirrhosis or chronic nonsuppurative destruction cholangitis are discussed. During a prospective search for cats with this disease, other hepatis lesions were found, and it was concluded that cats may be affected by more than one pathogenic mechanism culminating in chronic cholangitis or cholangiohepatitis.
Development of the glassy state of benzophenone and effect of heating rate from the glassy state on solidification

Benzophenone supercools to a glass when cooled to {minus}100 C. In fact, it is difficult to freeze benzophenone on cooling. In this investigation, the effect of cooling rate and the minimum cooling rate to obtain benzophenone as a glass is determined. From the glassy state, the influence of heating rate on the solidification temperature of benzophenone is determined. When heated at 3 C/min., solidification starts at about {minus}29 C. Upon additional heating, melting usually starts at about +24 C, which is 23 C lower than the solid equilibrium structure melting temperature of 47 C. Occasionally the solid that forms at about {minus}29 C undergoes a solid state phase transformation at about +22 C, when heated at 3 C/min. If this solid state phase transformation occurs, then the solid benzophenone starts to melt at 47 C. When solid benzophenone with the equilibrium structure is cooled to {minus}100 C, no solid state phase transformation occurs. It appears that the structure that solidified at {minus}29 C is metastable.
A time-accurate high-resolution TVD scheme for solving the Navier-Stokes equations

A total variation diminishing (TVD) scheme has been developed and incorporated into an existing time-accurate high-resolution Navier-Stokes code. The accuracy and the robustness of the resulting solution procedure have been assessed by performing many calculations in four different areas: shock tube flows, regular shock reflection, supersonic boundary layer, and shock boundary layer interactions. These numerical results compare well with corresponding exact solutions or experimental data.
Analysis of renal calculous matrix compared with some other matrix materials and with uromucoid.

Abstract Matrices recovered from pooled specimens of renal calculi, gall stones, and bone have been analyzed. The various matrices are clearly not identical in their over-all molecular composition. A urinary mucoprotein, uromucoid, is analytically more similar to renal calculons matrix than is matrix of other sorts examined.
Spilt milk: an unusual cause of bilateral chylothorax

We report a case of bilateral chylothorax without evidence of chylous fistula in a 62-year-old man following total laryngectomy and bilateral selective neck dissection for laryngeal cancer. Chylous fistulae, a well-known complication of neck dissection, occurs following 1% to 2% of these surgeries. On rare occasions, the chyle leak may communicate with the pleural space, resulting in chylothorax. This is a rare but potentially life-threatening complication. Bilateral chylothorax following neck dissection is even rarer, with less than 25 cases reported in the literature. Early diagnosis is essential to prevent complications. Physicians should have a high index of suspicion, especially when the postoperative effusions do not respond to diuretics. Though no evidence-based treatment guidelines exist, expert opinion recommends conservative management as first-line therapy. Our patient was effectively treated by conservative management. We postulate a mechanism whereby bilateral chylothorax occurred in our patient without a chylous fistula.
Expressing Death Risk as Condensed Life Experience and Death Intensity

Some risk exposures, including many medical and surgical procedures, typically carry hazards of death that are difficult to convey and appreciate in absolute terms. I propose presenting the death risk as a condensed life experience (i.e., the equivalent amount of life T that would carry the same cumulative mortality hazard for a person of the same age and sex based on life tables). For example, if the risk of death during an elective 1-hour procedure is 0.01%, and same-age and same-sex people have a 0.01% death risk over 1 month, one can inform the patient that "this procedure carries the same death risk as living 1 month of normal life." Comparative standards from other risky activities or from a person with the same disease at the same stage and same predictive profile could also be used. A complementary metric that may be useful to consider is the death intensity. The death intensity λ is the hazard function that shows the fold-risk estimate of dying compared with the reference person. The death intensity can vary substantially for different phases of the event, operation, or procedure (e.g., intraoperative, early postoperative, late postoperative), and this variability may also be useful to convey. T will vary depending on the time window for which it is computed. I present examples for calculating T and λ using literature data on accidents, ascent to Mount Everest, and medical and surgical procedures.
The C-terminal threonine of Aβ43 nucleates toxic aggregation via structural and dynamical changes in monomers and protofibrils.

Recent studies suggest that deposition of amyloid β (Aβ) into oligomeric aggregates and fibrils, hallmarks of Alzheimer’s disease, may be initiated by the aggregation of Aβ species other than the well-studied 40- and 42-residue forms, Aβ40 and Aβ42, respectively. Here we report on key structural, dynamic, and aggregation kinetic parameters of Aβ43, extended by a single threonine at the C-terminus relative to Aβ42. Using aggregation time course experiments, electron microscopy, and a combination of nuclear magnetic resonance measurements including backbone relaxation, dark-state exchange saturation transfer, and quantification of chemical shift differences and scalar coupling constants, we demonstrate that the C-terminal threonine in Aβ43 increases the rate and extent of protofibril aggregation and confers slow C-terminal motions in the monomeric and protofibril-bound forms of Aβ43. Relative to the neighboring residues, the hydrophilic Thr43 of Aβ43 favors direct contact with the protofibril surface more so than the C-terminus of Aβ40 or Aβ42. Taken together, these results demonstrate the potential of a small chemical modification to affect the properties of Aβ structure and aggregation, providing a mechanism for the potential role of Aβ43 as a primary nucleator of Aβ aggregates in Alzheimer’s disease.
Oxypurinol attenuates ischemia-induced hippocampal damage in the gerbil.

Abstract Oxypurinol, an inhibitor of the enzyme xanthine oxidase, reduced ischemic hippocampal damage and the associated hypermotility in Mongolian gerbils. Cerebral ischemia was induced in unanesthetized gerbils by a bilateral 5-min occlusion of the carotid arteries. Oxypurinol (40 mg/kg, IP), administered 20 min prior to carotid occlusion, prevented the increase in locomotor activity observed in saline-injected ischemic animals and significantly reduced the damage to, and loss of, CA1 hippocampal neurons observed 5 days postischemia. These findings suggest that Oxypurinol may be useful for the prevention of cerebral ischemic damage.
Three zebrafish MEF2 genes delineate somitic and cardiac muscle development in wild-type and mutant embryos

The zebrafish is an important experimental system for vertebrate embryology, and is well suited to the molecular analysis of muscle development. Transcription factors, such as the MEF2s, regulate skeletal and cardiac muscle-specific genes during development. We report the identification of three zebrafish MEF2 genes which, like their mammalian counterparts, encode factors that function as DNA-binding transcriptional activators of muscle specific promoters. The pattern of MEF2 expression in zebrafish defines discrete cell populations in the developing somites and heart and has mechanistic implications for developmental regulation of the MEF2 genes, when compared with other species. Alteration of MEF2 expression in two mutants affecting somitogenesis provides insight into the control of muscle formation in the embryo.
Augmented Mitral Valve Leaflet Area Decreases Leaflet Stress: A Finite Element Simulation

Background Using human mitral valve (MV) models derived from three-dimensional echocardiography, finite element analysis was used to predict mechanical leaflet and chordal stress. Subsequently, valve geometries were altered to examine the effects on stresses of the following: (1) varying coaptation area; (2) varying noncoapted leaflet tissue area; and (3) varying interleaflet coefficient of friction (μ). Methods Three human MV models were loaded with a transvalvular pressure of 80 mm Hg using finite element analysis. Initially leaflet coaptation was set to 10%, 50%, or 100% of actual coaptation length to test the influence of coaptation length on stress distribution. Next, leaflet surface areas were augmented by 1% overall and by 2% in the noncoapted "belly" region to test the influence of increased leaflet billowing without changing the gross geometry of the MV. Finally, the coefficient of friction between the coapted leaflets was set to μ = 0, 0.05, or 0.3, to assess the influence of friction on MV function. Results Leaflet coaptation length did not affect stress distribution in either the coapted or noncoapted leaflet regions; peak leaflet stress was 0.36 ± 0.17 MPa at 100%, 0.35 ± 0.14 MPa at 50%, and 0.35 ± 0.15 MPa at 10% coaptation lengths (p = 0.85). Similarly, coaptation length did not affect peak chordal tension (p = 0.74). Increasing the noncoapted leaflet area decreased the peak valvular stresses by 5 ± 2% (p = 0.02). Varying the coefficient of friction between leaflets did not alter leaflet or chordal stress distribution (p = 0.18). Conclusions Redundant MV leaflet tissue reduces mechanical stress on the noncoapted leaflets; the extent of coaptation or frictional interleaflet interaction does not independently influence leaflet stresses. Repair techniques that increase or preserve noncoapted leaflet area may decrease mechanical stresses and thereby enhance repair durability.
Magnetic loops, downflows, and convection in the solar corona

Optical and extreme-ultraviolet observations of solar loop structures show that flows of cool plasma from condensations near the loop apex are a common property of loops associated with radiations whose maximum temperature is greater than approximately 7000 K and less than approximately 3,000,000 K. It is suggested that the mass balance of these structures indicates reconnection by means of plasma motion across field lines under rather general circumstances (not only after flares). It is shown that the cool material has lower gas pressure than the surrounding coronal medium. The density structure of the bright extreme ultraviolet loops suggests that downflows of cool gas result from isobaric condensation of plasma that is either out of thermal equilibrium with the local energy deposition rate into the corona, or is thermally unstable. The evidence is thought to indicate that magnetic fields act to induce a pattern of forced convection.
Increasing preschoolers' physical activity intensities: an activity-friendly preschool playground intervention.

Abstract Objective The purpose of this study was to see if portable play equipment added to a preschool playground resulted in higher intensities of physical activity among 3–5-year-old children. Methods Activity-friendly equipment was added to an outdoor preschool playground. Accelerometry-measured intensities of 15-s epochs of physical activity were tracked for 5 pre-intervention and 5 post-intervention days during outdoor play. Data were collected during fall 2005 in Salt Lake City for 64 preschoolers aged 3, 4, and 5 years. Results After the intervention, both male and female 3- to 5-year-olds significantly decreased sedentary behavior and significantly increased light, moderate, and vigorous physical activity as measured by accelerometry. Conclusions Results suggest simple interventions, requiring little teacher training, can yield increases in healthy physical activity.
The Effect of Atmospheric Attenuators with Structured Vertical Distributions on Air Mass Determinations and Langley Plot Analyses

Abstract The effect of vertical inhomogeneities of atmospheric attenuators upon determinations of air mass and upon Langley plot determinations of the extra-atmospheric solar irradiance is examined and found to be significant, especially when accuracies of 0.1% are required, as in our current solar monitoring program. Ozone air mass values are found to differ greatly from those of the homogeneously mixed atmosphere for zenith angles greater than 60°.
The Research Library as Digital Curator at Virginia Tech

Research libraries provide a significant portion of the open access materials available on the Internet, and an examination of the efforts of one such library will illustrate the role of these institutions in creating the current information environment. The Virginia Tech University Libraries established the Scholarly Communications Project (SCP) even before the Gopher protocol opened up databases housed at research libraries to librarians with Internet access. The SCP was primarily intended to take advantage of evolving technologies to produce and distribute academic journals without the costs associated with traditional publishing, and that journal archive, the EJournals, is still at the heart of what has become the Digital Library and Archives (DLA).
Casimir energies in M4 >= N for even N. Green's-function and zeta-function techniques.

The Green's-function technique developed in the first paper in this series is generalized to apply to massive scalar, vector, second-order tensor, and Dirac spinor fields, as a preliminary to a full graviton calculation. The Casimir energies are of the form ${u}_{\mathrm{Casimir}}$=(1/${a}^{4}$)[${\ensuremath{\alpha}}_{N}$lna/b)+${\ensuremath{\beta}}_{N}$], where N (even) is the dimension of the internal sphere, a is its radius, and ${b}^{\mathrm{\ensuremath{-}}1}$ is an ultraviolet cutoff (presumably at the Planck scale). The coefficient of the divergent logarithm, ${\ensuremath{\alpha}}_{N}$, is unambiguously obtained for each field considered. The Green's-function technique gives rise to no difficulties in the evaluation of imaginary-mass-mode contributions to the Casimir energy. In addition, a new, simplified \ensuremath{\zeta}-function technique is presented which is very easily implemented by symbolic programs, and which, of course, gives the same results. An error in a previous \ensuremath{\zeta}-function calculation of the Casimir energy for even N is pointed out.
Optimal energy efficient scheme for MIMO-based cognitive radio networks with antenna selection

Multiple-input multiple-output (MIMO), which is also known as large-scale antenna system, is a promising technology for achieving the high spectrum efficiency of wireless communications networks. On the other hand, as a smart spectrum sharing technology, Cognitive Radio Network (CRN) is also expected to improve the utilization of spectrum usage for conciliating the current spectrum demand growth. Thus, the combination of MIMO and CRN has received extensive research attention in recent years. Although the large-scale antenna system can yield large network capacities, the radio-frequency (RF) chain also increases as the number of antennas gets large, which also increases the computational complexity, energy consumption, and hardware cost for the wireless networks. As a novel signal processing technology, antenna selection can reduce the number of RF chains while guaranteeing the performance under the system requirements. However, how to efficiently integrate these techniques to optimize energy efficiency still remains as an open and challenging problem. To overcome these challenges, in this paper we propose the optimal energy efficiency scheme for MIMO-based cognitive radio networks with antenna selection. In particular, we develop the joint transmit-power allocation and antenna subsets selection schemes for the transmitter to maximize the CRN's energy efficiency implemented under the constrains of the maximum interference caused by the secondary users (SU) to the primary users (PU), maximum transmission power from SU, and the minimum transmission rate in SU link. Finally, the obtained simulation results validate and evaluate our proposed schemes.
Doubling the number of women consuming vitamin supplement pills containing folic acid: An urgently needed birth defect prevention complement to the folic acid fortification of cereal grains

Abstract The major known environmental causes of birth defects are ancient agents that have been in the environment for centuries but have been only recently discovered—rubella, alcohol, and folic acid deficiency. In the United States, we have made great progress in preventing congenital rubella syndrome. We also have a great opportunity to prevent spina bifida and anencephaly (SBA) by increasing the number of women who daily consume vitamin supplements containing folic acid. Even with the recently announced grain fortification regulations, there are 45 million women unprotected from an SBA-affected pregnancy. This article suggests that a substantial educational campaign could, over a 5-year period, double the number of women consuming folic acid supplement pills and make a substantial contribution toward preventing SBA.
Comparison of phospholipids in vaginal and amniocentesis specimens of patients with premature rupture of membranes.

Abstract Amniotic fluid was obtained from the vaginal pool and by transabdominal amniocentesis in 28 patients who were admitted to the hospital between 26 and 35 weeks' gestation with premature rupture of the membranes. Phospholipid profiles were obtained on all specimens with the use of high-performance liquid chromatography. The lecithin/sphingomyelin ratio, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine, and lysolecithin were all analyzed to determine the effect of vaginal contamination. With the use of a paired t test, only lysolecithin was shown to be significantly affected by vaginal contamination (p
Pilot Pest Management Program for Grapes in Erie County, Pennsylvania

During the summers of 1976–77, a pilot pest management program for grapes was tested in Erie Co., Pennsylvania. Nine growers participated in 1976 (135.6 ha) and 14 growers participated in 1977 (214.0 ha). Vineyards were scouted weekly for 15 wk beginning June 1. Growers used the resulting information on insect and mite populations to optimize their spray practices. Avg number of postbloom insecticide applications in 1976 was 2.5 for nonparticipants and 0.8 applications for participants and in 1977 was 2.3 applications for nonparticipants and 1.1 applications for participants. Scouting costs, including cost of attractant traps, averaged $.30/0.4 ha per wk.
Computerized epileptiform transient detection in the scalp electroencephalogram: obstacles to progress and the example of computerized ECG interpretation.

Computerized detection of epileptiform transients (ETs), also called spikes and sharp waves, in the electroencephalogram (EEG) has been a research goal for the last 40 years. A reliable method for detecting ETs could improve efficiency in reviewing long EEG recordings and assist physicians in interpreting routine EEGs. Computer algorithms developed so far for detecting ETs are not as reliable as human expert interpreters, mostly due to the large number of false positive detections. Typical methods for ET detection include measuring waveform morphology, detecting signal non-stationarity, and power spectrum analysis. Some progress has been made by using more advanced algorithmic approaches including wavelet analysis, artificial neural networks, and dipole analysis. Comparing the performance of different algorithms is difficult since each study uses its own EEG test dataset. In order to overcome this problem, European researchers in the field of computerized electrocardiogram interpretation organized a large multi-center research workgroup to create a standardized dataset of ECG recordings which were interpreted by a large group of cardiologists. EEG researchers need to follow this as a model and seek funding for the creation of a standardized EEG research dataset to develop ET detection algorithms and certify commercial software.
Status of the Texas A&M GUT Monopole Search

We present here a report on the status of the GUT monopole search being staged by the Texas A&M University group. This experiment is located underground at a depth of 1500′ in a nearby salt mine and utilizes a large area (∼ 53 m2) scintillation counter telescope to detect the passage of a slow moving superheavy, magnetic monopole. A description of our detector and the expected signature for a passing magnetic monopole will be presented.
Ionization plus excitation in electron-atom collisions : (e, 2e), (e, eγ), and (e, 2eγ)

First-order benchmark results for ionization-excitation of helium using a convergent PWBA-RMPS model are presented. The relationship between (e,2e), (e,eγ), and (e,2eγ) experiments is discussed.
Heterodyne holographic interferometry: concentration and temperature measurements in gas mixtures

Heterodyne holographic interferometry is employed to measure refractive-index distributions in transparent media. A system using a He–Ne laser and relatively modest electronic instrumentation is described. The system was used to measure temperature and specie-concentration distribution in natural convection boundary layers in air adjacent to heated surfaces through which a second gas is emitted or injected.
Improvements within the A.V. Hill model structure: strengths and limitations

An assessment is made of the strengths and weaknesses of Hill-based muscle models, in particular as compared on purely mechanical grounds to more complex kinetic models. It is seen that the Hill model in its basic form is adequate for a wide variety of movement tasks but on the surface appears to fail in a few specific situations. A number of extensions are proposed that essentially remedy these problems, the primary one being the addition of a yielding effect produced by making the input to the contractile element dependent on recent mechanical history. This modified model displays the capacity to simulate history-dependent muscle behaviors not previously possible with Hill-based models while keeping relations for the mechanical machinery intact. >
Effect of sympathetic nerves on composition and distensibility of cerebral arterioles in rats.

1. The goals of this study were to examine the effects of chronic sympathetic denervation on the mechanics and composition of cerebral arterioles in normotensive Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). 2. We used an in vivo method to examine the mechanics of pial arterioles in 10- to 12-month-old, anaesthetized WKY and SHRSP that had undergone unilateral removal of the superior cervical ganglion at 1 month of age. Bilateral craniotomies were performed in each rat to expose pial arterioles in the innervated and denervated cerebral hemispheres. Arterioles were deactivated with EDTA. Incremental distensibility and stress-strain relationships were calculated from measurements of pial arteriolar pressure (servo null), diameter and cross-sectional area of the arteriolar wall. Point counting stereology was used to quantify volume density and cross-sectional area of individual components in the arteriolar wall. 3. Chronic sympathetic denervation reduced cross-sectional area of the arteriolar wall by 16 +/- 2% (mean +/- S.E. of mean; P less than 0.05) in WKY and 44 +/- 3% in SHRSP. During maximal dilatation with EDTA, incremental distensibility was reduced and the stress-strain curve was shifted to the left in denervated arterioles of SHRSP, but not WKY. These findings indicate that sympathetic denervation in SHRSP attenuates the development of hypertrophy in pial arterioles and reduces arteriolar distensibility. The ratio of non-distensible (collagen and basement membrane) to distensible (smooth muscle, elastin and endothelium) components was reduced in denervated arterioles in SHRSP, but not WKY. 4. Thus, sympathetic nerves have trophic effects on cerebral arterioles in WKY and, to a greater degree, in SHRSP. Sympathetic nerves also contribute to increases in distensibility of cerebral arterioles in SHRSP, but not WKY. The increase in arteriolar distensibility is accompanied by a disproportionate increase in the more compliant elements of cerebral arterioles.
Analysis and Quantitation of mRNAs Encoding the α- and β-Subunits of Rod Photoreceptor cGMP Phosphodiesterase in Neonatal Retinal Degeneration ( rd ) Mouse Retinas

Abstract The retinal degeneration ( rd ) mouse is a commonly-studied animal model of the family of human-inherited retinal blindness known as retinitis pigmentosa, and is a likely model in which therapies for these conditions will continue to be developed and tested. Mutation of the β-subunit of the rod photoreceptor cell-specific cyclic GMP phosphodiesterase is known to cause photoreceptor apoptosis in these mice. However, the molecular phenotype of this mutation in terms of quantitative levels of the phosphodiesterase α- and β-subunit messenger RNAs remains unknown. In this study, the expression of the α- and β-phosphodiesterase subunits is compared in C57BL/6J +/+, rd /+, and rd / rd mouse retinas. Using the techniques of quantitative reverse transcription polymerase chain reaction and quantitative in situ hybridization, the expression of the subunit mRNAs was measured in retinas of postnatal mice 0–14 days of age. Additionally, full length coding sequences were amplified for both subunits, and the β-phosphodiesterase subunit mRNA was further evaluated for evidence of alternative splicing. Lastly, a relative decrease in expression of the mutant β-phosphodiesterase allele in rd /+ mice was observed.
A Study of the Stability of Longitudinally Ribbed Rectangular Plates

ABSTRACT In engineering practice, plates are often reinforced by longitudinal ribs. These ribs introduce structural anisotropy. Consequently, classical plate theory for isotropic plates must be modified to account for this anisotropy. The response of such plate structures is described analytically by the theory of orthotropic plates, provided that the plate-rib structure is accurately modeled as an equivalent orthotropic plate. In previous work by the authors [1], a simplified procedure for determining plate rigidities was suggested. The suggested solution has been shown to be a reasonable approximation for the deflection of cross ribbed plates. This investigation is an application of the solution of Ref. 1 to the stability of the longitudinally ribbed plate.
Workplace helping: Interactive effects of personality and momentary positive affect.

We investigated interactions between positive affect and personality (empathy and altruism) as predictors of workplace helping. We conducted an experience sampling study with 80 participants, each of whom completed personality instruments and responded to a maximum of 5 electronic surveys per day for 5 workdays. This approach allowed us to study relationships over time between momentary positive affect and workplace helping behavior. We found that affect's relationship with later helping depended on the personality trait of altruism. We also found evidence that the relationship was reciprocal—helping others lead to increased positive affect, but again the relationship depended on altruism.