cssi/SciSciGPT-SciSciNet huggingface dataset:
SU-8 2002 Surface Micromachined Deformable Membrane Mirrors

This paper describes two surface micromachining processes, i.e., one using a wet-etch release and the other using a dry-etch release, to create deformable membrane mirrors made from a thin film of low-stress SU-8 2002. The mirrors are designed for electronic focus and aberration control in imaging systems, and exhibit a large range of motion and high optical quality. The processes result in free-standing membrane mirrors with in-plane film stress as low as 12.5 MPa while attaining well-defined lithographic features as small as 3 μm in a 2.5-μm-thick film. We achieved a maximum deflection of 14.8 μm for a 3-mm × 4.24-mm elliptical boundary mirror, limited by electrostatic pull-in. Using a 3-mm × 4.24-mm mirror, which is designed for operation with a circular beam at 45° incidence angle, we demonstrate focus control while compensating spherical aberration in an optical microscope over a depth of 137 μm using a 50× 0.4-NA objective lens.
Evidence for the formation of azides in the N sub 2 H sub 4 /N sub 2 O sub 4 reaction.

Azides and hydrazoic acid formation as intermediates involved with pressure spiking when restarting nitrogen tetroxide-hydrazine engines in vacuum
Mass Transport of Low Density Lipoprotein in Reconstructed Hemodynamic Environments of Human Carotid Arteries: The Role of Volume and Solute Flux Through the Endothelium

The accumulation of low density lipoprotein (LDL) in the arterial intima is a critical step in the initiation and progression of atheromatous lesions. In this study we examine subject-specific LDL transport into the intima of carotid bifurcations in three human subjects using a three-pore model for LDL mass transfer. Subject-specific carotid artery computational models were derived using magnetic resonance imaging (MRI) to obtain the geometry and phase-contract MRI (PC-MRI) to acquire pulsatile inflow and outflow boundary conditions for each subject. The subjects were selected to represent a wide range of anatomical configurations and different stages of atherosclerotic development from mild to moderate intimal thickening. A fluid-solid interaction (FSI) model was implemented in the computational fluid dynamics (CFD) approach in order to consider the effects of a compliant vessel on wall shear stress (WSS). The WSS-dependent response of the endothelium to LDL mass transfer was modeled by multiple pathways to include the contributions of leaky junctions, normal junctions, and transcytosis to LDL solute and plasma volume flux from the lumen into the intima. Time averaged WSS (TAWSS) over the cardiac cycle was computed to represent the spatial WSS distribution, and wall thickness (WTH) was determined from black blood MRI (BBMRI) so as to visualize intimal thickening patterns in the bifurcations. The regions which are exposed to low TAWSS correspond to elevated WTH and higher mass and volume flux via the leaky junctions. In all subjects, the maximum LDL solute flux was observed to be immediately downstream of the stenosis, supporting observations that existing atherosclerotic lesions tend to progress in the downstream direction of the stenosis.
Sex Differences in Attitudes Toward Homosexual Persons, Behaviors, and Civil Rights A Meta-Analysis

Meta-analytic techniques were used to compare men's and women's attitudes toward homosexual persons, homosexual behaviors, and gay people's civil rights. As expected, size of sex differences varied across these categories. Men were more negative than women toward homosexual persons and homosexual behavior, but the sexes viewed gay civil rights similarly. Men's attitudes toward homosexual persons were particularly negative when the person being rated was a gay man or of unspecified sex. Women and men evaluated lesbians similarly. Ratings of homosexual persons and homosexual behavior were least likely to differ by subject sex for samples of nonprofessional adults. In addition, sex role attitude mediated sex differences in attitudes toward homosexuality. Biases in the research literature and areas that deserve further attention, such as the confounding of sample with measurement strategy and the tendency to study gay men or targets of unspecified sex, are discussed.
Exact Solution for Thermoelastic Deformations of Functionally Graded Thick Rectangular Plates

An exact solution is obtained for three-dimensional deformations of a simply supported functionally graded rectangular plate subjected to mechanical and thermal loads on its top and/or bottom surfaces. Suitable temperature and displacement functions that identically satisfy boundary conditions at the edges are used to reduce the partial differential equations governing the thermomechanical deformations to a set of coupled ordinary differential equations in the thickness coordinate, which are then solved by employing the power series method. The exact solution is applicable to both thick and thin plates. Results are presented for two-constituent metal‐ceramic functionally graded rectangular plates that have a power law through-the-thickness variation of the volume fractions of the constituents. The effective material properties at a point are estimated by either the Mori‐Tanaka or the self-consistentschemes. Exact displacementsand stressesatseveral locations for mechanical and thermal loads are used toassess theaccuracyof the classical plate theory, thee rst-ordershear deformation theory, and athird-order shear deformation theory for functionally graded plates. Results are alsocomputed for a functionally graded plate with material properties derived by the Mori‐Tanaka method, the self-consistent scheme, and a combination of these two methods.
Mechanical Strain Increases Protein Tyrosine Phosphorylation in Airway Smooth Muscle Cells

Abstract Mechanical stress contributes to normal structure and function of the lung as well as pathology in such diseases as bronchopulmonary dysplasia and adult respiratory distress syndrome. Stress-related increases in airway smooth muscle (ASM) quantity are reflectedin vitrowhere cultured ASM cells respond to cyclic deformational strain with increased proliferation, cell reorientation, protein production, stress fibers, and focal adhesions. To understand the mechanisms of mechanical signaling in ASM cells, we investigated whether strain increased tyrosine phosphorylation of focal adhesion-related proteins. ASM cells were grown to confluence on collagen type I and subjected to 30 min of cyclic deformation strain (2 s of 25% deformation of the substratum, 2 s relaxation) and compared at various time points with identical cells not subjected to strain for phosphotyrosine content of three focal adhesion-concentrated proteins (pp125FAK, paxillin, and talin) by Western blotting. Strain caused a rapid increase in tyrosine phosphorylation of pp125FAKand paxillin. Tyrosine phosphorylation decreased by 4 h in pp125FAKafter discontinuing strain but remained elevated in paxillin at 24 h. Increases in tyrosine phosphorylation of talin were not found. In separate studies, when cells were strained in the presence of tyrosine kinase inhibitors (genistein and herbimycin A), strain-induced reorientation and elongation were inhibited. Mechanochemical signal transduction appears to mediate cell morphologic changes through quantitative and possibly qualitative changes in tyrosine phosphorylation of adhesion-related proteins.
Discretization techniques for the efficient solution of the eigenvalue problem in heterostructures

A systematic development of efficient discretization schemes for the numerical evaluation of the eigenvalues of the single-band effective mass equation that describes the motion of electrons in an ideal periodic crystal is presented. The approach presented makes use of the translational symmetry of the crystal lattice and utilizes the quantum mechanical properties of the momentum operator as the generator of spatial translation. Boundary conditions satisfied at the heterointerfaces are explicitly incorporated in the discretization procedure and the effects of this approach in overall accuracy are evaluated by studying a prototype quantum well heterostructure. Copyright © 2008 John Wiley & Sons, Ltd.
Specific heat measurements on superconducting Ce-La alloys

Abstract In CexLa1−x alloys one can study the co-existence of the Kondo effect and superconductivity. The first electron tunneling measurements by Edelstein on such a system were made on this alloy system. These measurements on alloy films showed that these alloys were gapless at the concentrations investigated. The number of states at the Fermi surface in the concentration range 0.002 ⩽ x ⩽ 0.005 was proportional to the impurity concentration. If the first Born approximation were applicable, there would not have been any states. Hence, unlike the Kondo effect these measurements provided direct microscopic evidence for the failure of the first Born approximation. Specific heat measurements on bulk samples indicate that the tunneling results were indicative of bulk samples. The low temperature (0.5 K ⩽ T ⩽ 3.0 K) specific heat contains a γT term. Such a term implies the existence of states at and around the Fermi surface. For x = 0.001, 0.002, 0.005, and 0.0075 values of γ = 0.11±0.08, 0.90±0.05, 2.40±0.20, and 4.66±0.04 mJ/moleK2 were obtained. These specific heat results are in agreement with the tunneling results. The fact that there is a critical Ce concentration below which there are no states at the Fermi level has important theoretical implications.
The New Norm: Community Colleges to Deal with Recessionary Fallout

Since the beginning of the Great Recession, many community colleges have experienced significant declines in state revenue, increases in enrollment, higher tuition, and flat or declining state student aid. These conditions have also occurred in an environment of heightened accountability with pressure to advance a student success agenda and to meet workforce training needs. Findings from the annual survey of state community college directors conducted by the Education Policy Center at the University of Alabama, in partnership with Iowa State University and The University of North Carolina at Charlotte, show that the majority of state directors feel states are moving toward a privatized model of higher education and that structural deficits exist in state budgets disadvantaging community colleges. The concern is that these and other related findings demonstrate a situation that may not improve as the nation climbs out of recession; this situation is creating a new norm in community college funding.
The United States Food Policy

Programs implementing U.S. food-assistance policy still currently lack support by many congressional representatives despite the fact that their curtailment will lead to there being more hungry children, more people going hungry among our elderly population, and ultimately more debility and dependency among vulnerable groups in our population. As it is, more than one in every twelve U.S. children under the age of twelve is hungry on a consistent basis. Table 1 provides estimates of the number of people in the United States suffering from hunger. This address consists of an identification of
Molecular biology and its impact for the future.

0 ver the past few decades, physicians have watched cardiovascular disease therapy move from largely empiric to more sophisticated treatments based on physiologic principles and, more recently, molecular biology. Cardiology has been slower than other disciplines to move into the arena. Aspects of molecular genetics are nearly 4 decades old, dating from the 1940s including the classic experiments of Watson and Crick on the structure and function of deoxyribonucleic acid (DNA). In much the same manner as cardiology demystified hemodynamics in the 1960s and 1970s and incorporated its principles into everyday practice, the near future will see the use of the molecular biologic techniques that are fundamental to all disciplines of medicine and industry.
Testing Students with Special Needs: A Model for Understanding the Interaction between Assessment and Student Characteristics in a Universally Designed Environment.

This article presents a model of assessment development integrating student characteristics with the conceptualization, design, and implementation of standardized achievement tests. The model extends the assessment triangle proposed by the National Research Council (Pellegrino, Chudowsky, & Glaser, 2001) to consider the needs of students with disabilities and English learners on two dimensions: cognitive interaction and observation interaction. Specific steps in the test development cycle for including students with special needs are proposed following the guidelines provided byDowning (2006). Because this model of test development considers the range of student needs before test development commences, student characteristics are supported by applying the principles of universal design and appropriately aligning accommodations to address student needs. Specific guidelines for test development are presented.
Peri-Saccadic Natural Vision

The fundamental role of the visual system is to guide behavior in natural environments. To optimize information transmission, many animals have evolved a non-homogeneous retina and serially sample visual scenes by saccadic eye movements. Such eye movements, however, introduce high-speed retinal motion and decouple external and internal reference frames. Until now, these processes have only been studied with unnatural stimuli, eye movement behavior, and tasks. These experiments confound retinotopic and geotopic coordinate systems and may probe a non-representative functional range. Here we develop a real-time, gaze-contingent display with precise spatiotemporal control over high-definition natural movies. In an active condition, human observers freely watched nature documentaries and indicated the location of periodic narrow-band contrast increments relative to their gaze position. In a passive condition under central fixation, the same retinal input was replayed to each observer by updating the video's screen position. Comparison of visual sensitivity between conditions revealed three mechanisms that the visual system has adapted to compensate for peri-saccadic vision changes. Under natural conditions we show that reduced visual sensitivity during eye movements can be explained simply by the high retinal speed during a saccade without recourse to an extra-retinal mechanism of active suppression; we give evidence for enhanced sensitivity immediately after an eye movement indicative of visual receptive fields remapping in anticipation of forthcoming spatial structure; and we demonstrate that perceptual decisions can be made in world rather than retinal coordinates.
A spectrophotometric method for the assay of threonine dehydratase

Abstract The enzymic conversion of β-hydroxy α-amino acids to α-keto acids by ThrDH (sheep liver) was followed by a direct spectrophotometric method at 230 mμ. The assay was more sensitive to changes in keto acid concentrations than the 2,4-dinitrophenylhydrazone method because of the absence of the high and variable blanks of the latter method. However, in the applicable range of concentrations both methods gave the same results. This procedure is not handicapped by the physical properties inherent in the coupled reactions.
Our Experience With 171 Open Tracheostomies

Purpose Tracheotomy is one of the oldest surgical procedures known. There are multiple indications for tracheostomies. Operative complications have ranged between 5-40%. This manuscript describes our experience with 171 open tracheostomies at a major academic medical center. Methods A retrospective review of all patients’ records who underwent an open tracheostomy by the Division of OMS between July 1, 2007 to December 31, 2010 was performed. Specific information including indication for procedure, age of patient, type and size of tracheostomy tube, and any post-operative complications were compiled. Based on the data gathered, statistical analysis was performed to establish incidence of complications and its correlation to the specific indication for the tracheostomy. Trends and outcome assessments were then determined. Results Median age for tracheostomy in the group was 36 (17-89). Majority of tracheostomies were performed in conjunction with head and neck oncologic procedures (51%). Complication rate was 4.1% (7 patients out of 171). Conclusion Open tracheostomy is an extremely useful surgical procedure. If performed appropriately, it is associated with a low complication rate.
Quantitative monitoring by polymerase colony assay of known mutations resistant to ABL kinase inhibitors.

Quantitative monitoring by polymerase colony assay of known mutations resistant to ABL kinase inhibitors
Fractal dimensions of sinkholes

Abstract Sinkhole perimeters are probably fractals (D=1.209–1.558) for sinkholes with areas larger than 10,000 m2, based on area-perimeter plots of digitized data from karst surfaces developed on six geologic units in the United States. The sites in Florida, Kentucky, Indiana and Missouri were studied using maps with a scale of 1:24, 000. Size-number distributions of sinkhole perimeters and areas may also be fractal, although data for small sinkholes is needed for verification. Studies based on small-scale maps are needed to evaluate the number and roughness of small sinkhole populations.
Disialoganglioside GD2 and a novel tumor antigen: potential targets for immunotherapy of desmoplastic small round cell tumor.

Background Desmoplastic small round cell tumor (DSRCT) is an aggressive and often misdiagnosed neoplasm of children and young adults. It is chemotherapy-sensitive, yet patients often relapse off therapy because of residual microscopic disease at distant sites: peritoneum, liver, lymph node, and lung. Strategies directed at minimal residual disease (MRD) may be necessary for cure. Monoclonal antibodies selective for cell surface tumor-associated antigens may have utility for diagnosis and therapy of MRD, as recently demonstrated in advanced-stage neuroblastoma (JCO 16: 3053, 1998). We examined DSRCT samples for the expression of two tumor antigens that could serve as possible targets for antibody-based immunotherapeutic approaches. Procedures Using immunohistochemistry, we studied the expression of two antigens: (1) GD2 using antibody 3F8 and (2) a novel antigen using antibody 8H9 in a panel of 46 freshly frozen DSRCT. GD2 is a disialoganglioside, which is widely expressed among neuroectodermal tumors as well as adult sarcomas. 8H9 recognizes a 58 kDa surface antigen expressed among neuroectodermal, mesenchymal, and epithelial tumors with restricted expression on normal tissues. Results Thirty-two of 46 (70%) tumors were reactive with 3F8, and 44 of 46 (96%) with 8H9. Both GD2 and the 58 kDa antigen were localized to tumor cell membrane and stroma. In general, immunoreactivity was stronger and more homogeneous with 8H9 than with 3F8. There was no correlation between expression of either antigen or clinical outcome. Conclusions GD2 and the novel tumor antigen recognized by 8H9 are potential targets for immunodiagnosis and antibody-based therapy of DSRCT. Med Pediatr Oncol 2002;39:547–551. © 2002 Wiley-Liss, Inc.
Perihematoma edema: a potential translational target in intracerebral hemorrhage?

Secondary injury in intracerebral hemorrhage (ICH) is becoming increasingly well characterized and is the subject of intense investigations. After the initial injury caused by tissue disruption and mass effect of the hematoma, products of coagulation, clot retraction, and hemoglobin breakdown initiate a secondary cascade of deleterious events including apoptosis, necrosis, iron-mediated oxidative stress, inflammation, autophagy, and edema formation [1–3]. Tissue swelling, in particular, may contribute to neurological deterioration and disability.
Interplay of molecular modulation technique and stimulated raman scattering for generation of ultra-broadband radiation

Simultaneous rotational and vibrational Raman generation was observed in cooled deuterium gas. Strong vibrational generation leads unexpectedly to efficient rotational generation, while under different conditions the vibrational generation may suppress a self-starting stimulated rotational generation.
Singlet−Singlet, Triplet−Triplet, and “Optically-Controlled” Energy Transfer in Polychromophores. Preliminary Models for a Molecular Scale Shift Register

The photophysics of two trichromophoric molecules have been studied by a combination of absorption, fluorescence, phosphorescence, and laser flash photolysis. TRI-1 consists of phenanthrene and naphthalene terminal chromophores joined to a central biphenyl group by methyl ester bridges. Intramolecular singlet−singlet energy transfer (SSET) between the biphenyl and terminal chromophores occurs efficiently with kSSET > 6 × 1010 s-1. Longer range SSET from the naphthalene moiety to the phenanthrene group takes place with a lower rate, k ∼ 2.5 × 108 s-1. In TRI-2, the biphenyl moiety is replaced by a benzophenone group. SSET here occurs from the phenanthrene chromophore to the central benzophenone chromophore although with a significantly lower rate than the biphenyl → phenanthrene rate in TRI-1. This is likely due to the change in configuration (ππ* to nπ*) of the excited singlet states involved in the energy transfer. Triplet−triplet (TTET) energy transfer between biphenyl and the terminal chromophores is n...
A Note on the Businger-Dyer Profiles

In the micrometeorological literature, reference is sometimes made to the ‘Businger-Dyer Profiles’ or the ‘Dyer-Businger profiles/relations’ without referring to the origin of these relations. For example, in the textbook on ‘Atmospheric Turbulence’ by Panofsky and Dutton (1984) on p. 134, reference is made to the ‘Businger-Dyer formula’. To add to the mystery, these authors refer on p. 141 to the Businger-Dyer-Pandolfo empirical result (Businger, 1966; Pandolfo, 1966) that in unstable air $$ Ri = \frac{z}{L} \equiv \zeta $$ (1) .
Convention Center Wars and the Decline of Local Democracy

ABSTRACT Convention centers have emerged as a focal point in an intense competition among cities for a share of the economically important meetings and exhibition market. In this paper, we present abundant evidence to show that cities can substantially benefit by capturing a share of this market. However, the cost and size of the meetings facilities that are appropriate for particular cities will vary with local circumstances. We argue that such local considerations are ignored because of the political influence that the meetings industry now exerts when cities make decisions about building or expanding convention centers.
Critically reappraising the literature-driven practice of analgesia administration for acute abdominal pain in the emergency room prior to surgical evaluation

Abstract Background Classic teaching is that narcotic analgesia in the setting of an acute abdomen can alter physical examination findings and should therefore be withheld until after a surgeon’s examination. Methods A telephone survey of emergency medicine physicians representing 60 US hospitals was conducted to assess the current practices and opinions regarding the early administration of narcotic analgesia in this setting. Relevant literature was also reviewed for methodological errors. Results Fifty-nine of 60 (98.3%) respondents reported that it is their practice to administer analgesia prior to surgical evaluation. Of these, only 9 of 59 (15.3%) reported always informing the surgeon prior to dosing the patient. The two most common motivations cited were that patient discomfort takes precedence (52 of 59; 88.1%) and that the literature supports the practice to be safe (51 of 59; 86.4%). Conclusions It is common for emergency medicine physicians to medicate acute abdomen patients prior to surgical evaluation. Numerous significant study limitations and design flaws were found that question the validity of the four clinical trials supporting this practice. Because many physicians base their clinical decisions on these trials, a careful analysis of their shortcomings, as well as our own personal experiences and practice recommendations, is discussed.
Quality measurement and improvement in colonoscopy

Colonoscopy is now a widely accepted method of screening and surveillance of the colon for neoplastic lesions in patients over 50 years of age. The main advantage of colonoscopy as opposed to other screening tests is the ability to remove precancerous polyps at the time of their detection. However, colonoscopy may miss clinically important neoplastic lesions. The effectiveness of colonoscopy in reducing colorectal cancer incidence depends on adequate visualization of the entire colon and diligence in examining the mucosa. Factors such as inadequate bowel preparation, suboptimal colonoscopy technique, rapid withdrawal, ineffective polypectomy, and failure of physicians to recognize flat lesions can potentially influence the effectiveness of colonoscopy. Considerable variation has been reported in colonoscopy performance among centers and endoscopists. In recent years, various approaches have been advocated to improve the quality of colonoscopy; however, the overall impact of these interventions is not fully known. Understanding the biological and behavioral factors that contribute to variable detection, identifying corrective measures to both failed and variable detection, developing optimal educational measures, and studying the impact of newer technologies in improvement of quality will be essential in the future to maximize the effectiveness of colonoscopy.
Measurement of the hall mobility of injected electrons in liquid tetramethylsilane between 22 and 164 °C

Abstract We have measured the Hall mobility of excess electrons in liquid tetramethylsilane (TMS) between room temperature and 164°C. The novel result is that, within an experimental error of ≈10%, the Hall mobility μ h is equal to the drift mobility μ d ; μ h = 101 ± 7 cm 2 /V s at 22°C and 53 ± 5 cm 2 /Vs at 164°C. This indicates that, contrary to what is observed in neopentane, traps are unimportant and, in particular, are not responsible for the mobility drop observed close to the critical point in TMS .
A Mathematical Model of Transmission Line Audible Noise Part 1: Background and Model Development

A mathematical model is developed for transmission line corona audible noise (AN). The noise is described as the sum of the noises from a number of uncorrelated sources on the surface of the conductor. The intensity of each source is assumed to be a function of gradient and the number of sources is a function of rain rate, voltage gradient and the surface aging condition. Townsend's first ionization coefficient is used to relate the number of sources to the gradient. The steady state solution of the AN equation is plotted to show the variation of noise with gradient for various rain rates, and the variation of noise with rain rate for various gradients.
Observations of the distribution of manganese over the East Pacific Rise

Abstract When seawater circulates through hot basalt at active spreading centers, the manganese concentration of the seawater increases by ∼ 10 6 times. Eventually, this hydrothermal water is discharged back into ambient seawater through vents and fissures on the sea floor. Mn vs. silica relationships in water samples collected from active vent fields on the Galapagos Rift are linear but have different slopes. These relationships demonstrate that the Mn in the hydrothermal end-member mixes conservatively with ambient seawater (at least below 10°C) but the physical and chemical processes responsible for the Mn concentration of the hydrothermal fluid must be variable. The Mn concentrations measured for the Galapagos system predict that hydrothermal emanations are major sources of Mn to the oceans but only if these data are not anomalously high. This paper presents profiles of Mn in bottom waters at four locations along the East Pacific Rise (EPR) which support the hypothesis that Mn emanations comparable to those from the Galapagos are occurring along the EPR. Bottom water at one station in the Guatemala Basin, some 1000 km from the EPR crest, also has anomalously high Mn concentrations suggesting that this hydrothermal Mn signal can be transported far from the source.
Solar flares and magnetic topology

This article is a very brief review and comparison of the observational properties of flares and theoretical concepts of models of flares, especially the concepts of magnetic topology and its evolution. We examine the environmental aspects of flare behavior. Some of these aspects must be consequences of unknown processes occurring below the photosphere. Other aspects involve structures - such as filaments - that are closely related to flares. We then examine properties of flares to try to distinguish the different phases of energy release that can occur in the course of a flare. Finally a schematic scenario is offered to interpret these phases in terms of this scenario.
Mid-chain ketocarboxylic acids in the remote marine atmosphere: Distribution patterns and possible formation mechanisms

In remote marine aerosol samples collected from the North Pacific ocean, Enewetak Atoll, American Samoa, and New Zealand, series of mid-chain ketocarboxylic acids in the range of C6-C18 were detected. All the positional isomers, except for the 2-oxo and 3-oxo species, were detected for major ketoacid families (e.g. C9, C11 and C13). Higher ketoacid concentrations (up to 19 ng/m3) were obtained in the northern North Pacific aerosol samples, which generally showed an odd carbon-numbered predominance with 5-oxoundecanoic acid being the major species. By contrast, lower concentrations were obtained in the lower-latitude or subtropical aerosol samples, where even carbon-numbered ketoacids were relatively abundant.
Detritus feeding as a buffer to extinction at the end of the Cretaceous

At the end of the Cretaceous the principal animals that became extinct, such as dinosaurs, marine animals that lived in the water column, and benthic filter feeders, were in food chains tied directly to living plant matter. Animal groups less affected by extinction, including marine benthic scavengers and deposit feeders, small insectivorous mammals, and members of stream communities, were in food chains dependent on dead plant material. The proposal that an asteroid or comet impact at the end of the Cretaceous produced a dust cloud that cut off photosynthesis for several months is consistent with this pattern of extinction. Food chains dependent on living plant matter crashed, while food chains based on detritus were buffered from extinction because there was a food supply adequate for the interval when photosynthesis was halted.
Structure, stability, and surface diffusion of clusters: Irx on Ir(111)

Abstract The properties of clusters adsorbed on a crystal made of the same atoms are of interest in understanding crystal growth. Using the field ion microscope, we have therefore examined iridium clusters containing from 2 to 13 atoms held on the close-packed iridium (111) plane. The arrangement of iridium atoms in the clusters in relation to the binding sites for single atoms on Ir(111) has been determined in detailed mapping experiments. In all the clusters examined, atoms sit in nearest-neighbor sites. As the size of the cluster is increased, the likelihood of finding cluster atoms at bulk sites, at which addition of atoms propagates the normal fcc structure, also increases. From tetramers to Ir13, compact arrangements maximizing the number of close neighbors are favored. Measurements of the temperature for the onset of dissociation of these clusters reveal an unusual dependence of cluster cohesion upon size: the binding energy increases sharply from dimers to trimers, drops for tetramers, and then rises again. For clusters containing 5 or more atoms, the binding energy is relatively insensitive to size. The magnitude of the cohesive energy is also surprising; the bond energy amounts to only ∼ 1 4 that in a bulk crystal. Diffusion of the clusters over the surface is observed prior to dissociation, and the trends in the barrier to motion are similar to those in dissociation. However, for small clusters the activation energy rises more slowly than in dissociation, and for larger clusters it increases more rapidly. Quantitative determinations of the diffusion characteristics for dimers through pentamers again reveal an anomalously low activation energy for tetramers, but the prefactor is insensitive to cluster size, indicating that the mechanism of diffusion is the same independent of the number of cluster atoms. Detailed observations of cluster motion have been made at low temperatures, to identify the individual atomic events in diffusion. From these it appears that diffusion occurs by a series of single atom jumps. Although surface migration is found to be a reasonably simple process, the cohesive properties of these clusters appear quite sensitive to structure, and are markedly different from expectations based either on bulk properties, or on the behavior of clusters in the gas phase.
Functional analysis of conserved motifs in the mechanosensitive channel homolog MscS-Like2 from Arabidopsis thaliana.

The Mechanosensitive channel of Small conductance (MscS) of Escherichia coli has become an excellent model system for the structural, biophysical, and functional study of mechanosensitive ion channels. MscS, a complex channel with multiple states, contributes to protection against lysis upon osmotic downshock. MscS homologs are widely and abundantly dispersed among the bacterial and plant lineages, but are not found in animals. Investigation into the eukaryotic branch of the MscS family is in the beginning stages, and it remains unclear how much MscS homologs from eukaryotes resemble E. coli MscS with respect to structure, function, and regulation. Here we test the effect of mutating three conserved motifs on the function of MscS-Like (MSL)2, a MscS homolog localized to the plastids of Arabidopsis thaliana. We show that 1) a motif at the top of the cytoplasmic domain, referred to here as the PN(X)9N motif, is essential for MSL2 function and for its proper intraplastidic localization; 2) substituting polar residues for two large hydrophobic residues located in the predicted pore-lining transmembrane helix of MSL2 produces a likely gain-of-function allele, as previously shown for MscS; and 3) mis-expression of this allele causes severe defects in leaf growth, loss of chloroplast integrity, and abnormal starch accumulation. Thus, two of the three conserved motifs we analyzed are critical for MSL2 function, consistent with the conservation of structure and function between MscS family members in bacteria and plants. These results underscore the importance of plastidic mechanosensitive channels in the maintenance of normal plastid and leaf morphology.
Regulation of focal adhesion targeting and inhibitory functions of the FAK related protein FRNK using a novel estrogen receptor "switch".

Focal adhesion kinase (FAK) is a regulator of numerous adhesion-dependent processes including cell migration, cell proliferation, and cell survival. The C-terminal domain of FAK, FAK-related nonkinase (FRNK), is autonomously expressed and functions as an inhibitor of FAK signaling. Previous attempts to use FRNK as a tool to dissect FAK signaling have been limited because of an inability to temporally regulate the inhibitory functions of FRNK. In this report, we describe and characterize a conditionally targeted form of FRNK that was created by fusing the hormone-binding domain of the estrogen receptor (ER*) to the C-terminus of FRNK. In the absence of added hormone, FRNK-ER* was diffusely distributed throughout the cytoplasm of cells. Upon addition of hormone, the cytoplasmic pool of FRNK-ER* was rapidly redistributed to focal adhesions. We demonstrate that cells expressing FRNK-ER* show a hormone-dependent decrease in FAK tyrosine phosphorylation and cell migration. Furthermore, when cells expressing of FRNK-ER* were treated with hormone, the cells responded with a dramatic change in cell morphology, suggesting a role for FAK in the regulation of the adhesive properties of focal adhesions. Cell Motil. Cytoskeleton 51:76–88, 2002. © 2002 Wiley-Liss, Inc.
Residual sarcoplasmic reticulum Ca2+ concentration after Ca2+ release in skeletal myofibers from young adult and old mice.

Contrasting information suggests either almost complete depletion of sarcoplasmic reticulum (SR) Ca2+ or significant residual Ca2+ concentration after prolonged depolarization of the skeletal muscle fiber. The primary obstacle to resolving this controversy is the lack of genetically encoded Ca2+ indicators targeted to the SR that exhibit low-Ca2+ affinity, a fast biosensor: Ca2+ off-rate reaction, and can be expressed in myofibers from adult and older adult mammalian species. This work used the recently designed low-affinity Ca2+ sensor (Kd = 1.66 mM in the myofiber) CatchER (calcium sensor for detecting high concentrations in the ER) targeted to the SR, to investigate whether prolonged skeletal muscle fiber depolarization significantly alters residual SR Ca2+ with aging. We found CatchER a proper tool to investigate SR Ca2+ depletion in young adult and older adult mice, consistently tracking SR luminal Ca2+ release in response to brief and repetitive stimulation. We evoked SR Ca2+ release in whole-cell voltage-clamped flexor digitorum brevis muscle fibers from young and old FVB mice and tested the maximal SR Ca2+ release by directly activating the ryanodine receptor (RyR1) with 4-chloro-m-cresol in the same myofibers. Here, we report for the first time that the Ca2+ remaining in the SR after prolonged depolarization (2 s) in myofibers from aging (~220 μM) was larger than young (~132 μM) mice. These experiments indicate that SR Ca2+ is far from fully depleted under physiological conditions throughout life, and support the concept of excitation–contraction uncoupling in functional senescent myofibers.
Atomic ionization by ultra—strong laser fields

Abstract The problem of multi-photon ionization of hydrogen by ultra-strong electromagnetic fields is solved in the limit where the field energy is greater than the Coulomb energy. The transition rate goes to zero as the reciprocal of the field strength.
Direct plasma measurements in the Io torus and inner magnetosphere of Jupiter

The details of positive ion measurements made in the inner magnetosphere are discussed. Attention is also given to an analysis of these measurements to obtain plasma composition, flow speeds, and temperatures and to the assumptions made in the analysis. These results for the positive ions are then combined with the direct measurements of plasma electrons between 5.7 and 9 Jupiter radii and with a theoretical distribution of plasma along dipolar magnetic field lines to build a two-dimensional model of the plasma torus.
Reparametrization invariance reexamined

Reparametrization invariance, a symmetry of heavy quark effective theory, appears in different forms in the literature. The most commonly cited forms of the reparametrization transformation are shown to induce the same constraints on operators that do not vanish under the equation of motion to order 1/m{sup 2}, and to be related by a redefinition of the heavy quark field. We give a new, very straightforward proof that the reparametrization invariance constraints apply to all orders in {alpha}{sub s} under matching to full QCD and renormalization-group running, at least up to and including O(1/m{sup 2}). {copyright} {ital 1997} {ital The American Physical Society}
The role of the oxidative-stress in the endometriosis-related infertility

Endometriosis is a common gynecological disorder of the reproductive age characterised by pelvic pain, dysmenorrhea and infertility. Classic theories have failed to propose a precise pathogenetic mechanism. Recent studies have investigated the role of the immune system and oxidative stress in the development of endometriosis as well as the identification of biomarkers for a non-invasive diagnosis of the disease. At endometriotic sites, inflammatory cells including eosinophils, neutrophils and macrophages generate reactive oxygen species that contribute to the development of oxidative stress in the peritoneal cavity. Oxidative stress further augments immune response in affected sites. The oxidants exacerbate the development of endometriosis by inducing chemoattractants and endometrial cell growth-promoting activity. The oxidative proinflammatory state of the peritoneal fluid is an important mediator of endometriosis. Many studies investigate the correlation of endometriosis and oxidative stress but the results are discrepant. Furthermore, oxidative stress has been implicated in unexplained infertility and has been associated with some of its causative factors. Oxidative stress influences womens reproductive capacity. The association between endometriosis and infertility is described in several studies and still remains debated.
The effectiveness of adherence intervention in a colon cancer prevention field trial

Abstract Background. Adherence interventions were implemented in a 1-year community-based colon cancer prevention clinical trial ( n = 110) using wheat bran fiber and calcium dietary supplements. The adherence promotion strategy was guided by a theoretical model. Methods. The adherence intervention contains both a generalized portion given to all participants and an individualized portion given to marginal (50–74% intake) and low (under 50% intake) adherers. A regression model was employed to assess the effectiveness of the interventions both at the first intervention and at subsequent times. Results. The Health Behavior in Cancer Prevention Model-based adherence promotion intervention was associated with retention of participants, both during the run-in period and after randomization ( P = 0.05); and maximization of the percentage of the 13.5-g recommended fiber supplement consumed during the trial (92.5%). The positive effects of the adherence intervention were greater with first-time nonadherers and the control group than with the experimental group. The high-fiber group had notably more biological GI effects from the increased fiber intake, more preexisting comorbidities, and lower perceived cognitive and physical health status. Conclusions. Randomized participants had excellent adherence overall. Retention rates in the trial were better than would be expected without the adherence intervention, especially among those participants who may have been at higher risk for dropping out of the study. This suggests that a systematic, theoretically based adherence strategy should be further tested in clinical trial settings in which lower adherence is a problem.
Objective Assessment of Sonographic Quality I: Task Information

In this paper, we explore relationships between the performance of the ideal observer and information-based measures of class separability in the context of sonographic breast-lesion diagnosis. This investigation was motivated by a finding that, since the test statistic of the ideal observer in sonography is a quadratic function of the echo data, it is not generally normally distributed. We found for some types of boundary discrimination tasks often required for sonographic lesion diagnosis, the deviation of the test statistic from a normal distribution can be significant. Hence the usual relationships between performance and information metrics become uncertain. Using Monte Carlo studies involving five common sonographic lesion-discrimination tasks, we found in each case that the detectability index dA2 from receiver operating characteristic analysis was well approximated by the Kullback-Leibler divergence J, a measure of clinical task information available from the recorded radio-frequency echo data. However, the lesion signal-to-noise ratio, SNRI2, calculated from moments of the ideal observer test statistic, consistently underestimates dA2 for high-contrast boundary discrimination tasks. Thus, in a companion paper, we established a relationship between image-quality properties of the imaging system and J in order to predict ideal performance. These relationships provide a rigorous basis for sonographic instrument evaluation and design.
A radiographic sign of left sided mediastinal lymph node enlargement.

This report draws attention to an apparent clear space, which is normally present on routine chest posterior-anterior roentgenograms, composed of the descending aorta, pulmonary outflow tract and left upper lobe vessels which form its medial, inferior and lateral boundaries respectively. The medial margin of this space has a concave outer border. Lymph nodes of the ligamentum group lie in close proximity to this space. In the absence of other processes involving structures of the middle mediastinum, encroachment of this space from the medial direction, with formation of a convex outer border is a reliable and frequently the first radiographic sign of left-sided mediastinal lymph node enlargement
Fuzzy PD+I learning control for a pneumatic muscle

A fuzzy learning control technique is used for position tracking involving the vertical movement of a mass attached to a pneumatic muscle. Because the pneumatic muscle is nonlinear and time varying, conventional fixed controllers are less effective than the fuzzy controller proposed in this paper. The controller is of a PID type, with an adaptive fuzzy PD part and a nonfuzzy integral branch. A novelty of the controller is that the fuzzy inverse model, which dynamically adjusts the PD part of the controller, incorporates the internal PM pressure as an input. Experimental results are presented from the pneumatic muscle test facility in the Human Effectiveness Laboratory at Wright-Patterson Air Force Base.
Experimental analysis of millimeter wave coplanar waveguide slow wave structures on GaAs

Microwave coplanar waveguide slow wave structures suitable for use in traveling wave electrooptic modulators were experimentally investigated to 40 GHz. Velocity slowing is achieved by introducing periodic slots in the ground planes. Structures both on semiinsulating GaAs substrates and on epitaxial layers grown by molecular beam epitaxy on semiinsulating GaAs substrates were examined. In the measurements the thru-reflect-line calibration method was used and its limitations are discussed. The characteristic impedance, phase velocity and loss coefficient of these lines were extracted from measured S-parameters. Effects of various dimensions on these line properties are presented and discussed. Results indicate that significant phase velocity slowing without dispersion at least up to 40 GHz is possible with this approach. This is true both on semi-insulating GaAs substrates and specially designed epitaxial layers. A design approach to achieve a specified phase velocity and characteristic impedance is given. >
The mechanism of apical dominance in Coleus

The development of lateral buds in isolated stems of Coleus blumei is inhibited by low concentrations of indoleacetic acid or other auxins, just as in other plants. The inhibition can be fully reversed by kinetin, about 3 times as much kinetin as IAA being needed. However, the outgrowth of the same lateral buds on intact Coleus plants is sensitive to environmental conditions, well-nourished plants in full daylight often showing little inhibition by applied auxin. It is shown that (a) the solvent used for IAA, (b) the light intensity and (c) the nitrogen and phosphorus nutrition, all control the sensitivity of the buds to auxin inhibition. Using water instead of lanolin, lowering the light intensity or decreasing the supply of either nitrogen or phosphorus all increase the degree of apical dominance.