cssi/SciSciGPT-SciSciNet huggingface dataset:
How do albatrosses fly around the world without flapping their wings

Abstract Albatrosses fly long distances over the Southern Ocean, even around the world, almost without flapping their wings; this has raised interest in how they perform such a feat. On a cruise to the South Atlantic I observed albatrosses soaring in a characteristic swooping zigzag flight that appears to combine two soaring techniques to gain energy—wind–shear soaring (dynamic soaring) using the vertical gradient of wind velocity and wave-slope soaring using updrafts over waves. The observed characteristic swooping flight is shown in a new illustration and interpreted in terms of the two soaring techniques. The energy gain estimated for “typical conditions” in the Southern Ocean suggests that wind–shear soaring provides around 80–90% of the total energy required for sustained soaring. A much smaller percentage is provided by wind shear in light winds and significant swell when wave-slope soaring dominates. A simple dynamical model of wind–shear soaring is proposed based on the concept of a bird flying across a sharp wind–shear layer as first described by Lord Rayleigh in 1883 and later developed with Pennycuick’s (2002) description of albatrosses “gust soaring.” In gust soaring a bird exploits structures in the wind field, such as separated boundary layers and eddies in the lee of wave crests, to obtain energy by climbing headed upwind and descending headed downwind across a thin wind–shear layer. Benefits of the model are that it is simple to understand, it captures the essential dynamics of wind–shear soaring, and it provides reasonable estimates of the minimum wind shear required for travel velocity in different directions with respect to the wind. Travel velocities, given in a travel velocity polar diagram, can be combined with tacking to fly in an upwind direction faster than the wind speed located at the top of the wind–shear layer.
A model T-cell receptor system for studying memory T-cell development

When T-cell clones were first grown in long-term cell culture, each clone was considered to be capable of displaying a limited range of functional activities, constrained by the clones' coreceptor, CD4 or CD8, and the specificity of its antigen-specific receptor (TCR) for one or a few peptides in association with a class I or class II MHC molecule. Subsequent studies, especially with transgenic mice, have shown, however, that T cells expressing the same receptor can be obtained in a variety of differentiated states, including naive cells, activated effector cells, memory cells, and anergic or tolerant cells, as well as cells with or without a coreceptor. In each of these states T cells can display distinctly different responses to the peptide-MHC (pepMHC) complexes the TCR recognizes. Recently, memory T cells have received considerable attention, in part because of the likelihood that they confer long-term protective immunity against diverse infectious agents and possibly against some forms of cancer. Here we review some recent studies that our colleagues and we have carried out on memory CD8(+) T cells. These studies have made extensive use of cells that express the TCR called 2C. The diverse set of cells expressing the 2C TCR, in mice and in cultured clones and cell lines, are referred to as the 2C system. Before reviewing the studies of memory cells, we summarize the 2C system's main features, including evidence that a large and diverse array of pepMHC complexes, involving at least four class I MHC proteins, can stimulate TCR-mediated responses of 2C cells.
A new DNA-delay mutation in bacteriophage T4D

Abstract A bacteriophage T4D strain carrying a mutation, dsd , has been isolated following recombination between wild-type and strain y 100 ,. The strain carrying dsd had a reduced burst size, a delayed latent period, a delay in DNA synthesis, an increase in genetic recombination, and a normal sensitivity to ultraviolet irradiation. Data from two- and three-factor crosses showed that the dsd mutation was located between genes 40 and 41 on the genetic map. The dsd strain complemented strains mutant in genes 40 and 41 and thus is not likely to be mutant in either of these genes. The strain carrying dsd has properties similar to the DNA-delay (DD) mutants of T4. Studies with multiple mutants indicated that the product of dsd interacts with the products of the DD genes 39, 52 , and 60 in a complex fashion. Gene 58 , however, appears to control a step in DNA synthesis which is independent of dsd product.
Effect of uniaxial stress on the magnetophonon effect in n-InSb

Abstract The effect of uniaxial compressional stress on the magnetophonon oscillations in low concentration n -type InSb was investigated at 77°K. The application of stress increased the frequency of oscillation and hence the cyclotron effective mass, which is proportional to the frequency. The experimental changes in frequency depended upon the directions of both the uniaxial stress and the magnetic field. The experimental data is explained quite accurately in terms of a theoretical model using the following values of the deformation potentials: a + C 1 = −6.1 ± 0.1 eV, b = −2.0 ± 0.2 eV, d = −5.0 ± 0.2 eV, and C 2 = 1 ± 1 eV. These values are compared with those determined by other methods.
Terminal Differentiation of Human Breast Cancer through PPARγ

We have previously demonstrated that PPAR gamma stimulates the terminal differentiation of adipocyte precursors when activated by synthetic ligands, such as the antidiabetic thiazolidinedione (TZD) drugs. We show here that PPAR gamma is expressed at significant levels in human primary and metastatic breast adenocarcinomas. Ligand activation of this receptor in cultured breast cancer cells causes extensive lipid accumulation, changes in breast epithelial gene expression associated with a more differentiated, less malignant state, and a reduction in growth rate and clonogenic capacity of the cells. Inhibition of MAP kinase, shown previously to be a powerful negative regulator of PPAR gamma, improves the TZD ligand sensitivity of nonresponsive cells. These data suggest that the PPAR gamma transcriptional pathway can induce terminal differentiation of malignant breast epithelial cells and thus may provide a novel, nontoxic therapy for human breast cancer.
Long-term potentiation of guinea pig mossy fiber responses is not blocked by N-methyl d-aspartate antagonists

Abstract Receptors preferentially activated by the excitatory amino acid N-methyl- d -aspartate (NMDA) do not mediate synaptic transmission in the hippocampus but are involved in initiating long-term potentiation (LTP) in hippocampal region CA 1 . We have examined the role of NMDA receptors in LTP of the commissural/associational and mossy fiber pathways to region CA 3 pyramidal neurons. In the commissural/associational pathway, NMDA receptor blockers did not reduce synaptic responses but reversibly blocked the induction of LTP. In contrast, NMDA receptor blockers had no effect on mossy fiber LTP. These results suggest that induction of commissural/associational LTP differs from mossy fiber LTP, although the mechanisms underlying expression of LTP along these pathways could be similar. Kynurenate and l -2-amino-4-phosphonobutyrate, which potently reduce mossy fiber responses, also did not block induction of mossy fiber LTP.
Transtelephonic echocardiography: Successful use in a tertiary pediatric referral center

Recent advances in computers and telecommunications have made transtelephonic echocardiography practical. Our institution is developing a network of transmissional echocardiographic sites at several hospitals in our referral region. We reviewed our initial experience to determine whether transmissional echocardiographic studies (1) gave an appropriate diagnostic impression compared with subsequent videotape review and (2) led to appropriate clinical management (i.e., transfer to a tertiary center or continuation of local care and follow-up). From Aug. 1,1991, to May 31,1992, we evaluated 47 transmissional studies (diagnoses: 24 normal, 8 patent ductus arteriosus, 6 ventricular septal defect, 2 pulmonary stenosis, 1 ventricular septal defect with interrupted aortic arch, and 6 miscellaneous). Of 47 studies, 39 (83%) were thought to give accurate diagnostic impressions compared with videotape review. Most inaccuracies were due to the selection and transmission of inconclusive information in an otherwise accurate diagnostic study. Only 1 (2%) of 47 studies resulted in an inappropriate clinical decision; a patient's transfer for treatment of a patent ductus arteriosus was delayed 1 day because of an inconclusive transmissional study. We conclude that transmissional echocardiography is useful in the management of pediatric patients with suspected heart disease in a regional referral setting.
Abstract B138: Harnessing the glycolytic switch for therapy in a novel mouse model of anaplastic thyroid carcinoma.

Most cancer cells exhibit a peculiar metabolic behavior, producing energy by aerobic glycolysis instead of oxidative phosphorylation (Warburg effect). Several oncogenes directly drive this switch modulating the levels and activity of, among others, Hexokinase II, Lactate Dehydrogenase A, Pyruvate Kinase M2, and Pyruvate Dehydrogenase Kinase 1. Anaplastic thyroid carcinoma (ATC) is the most aggressive form of thyroid cancer, and often derives from pre-existing well-differentiated tumors. Despite a relatively low prevalence, it accounts for a disproportionate number of thyroid cancer-related deaths, due to its resistance to any therapeutic approach. We have engineered the first mouse model of ATC by combining in the mouse thyroid follicular cells two molecular hallmarks of human ATC: activation of PI3K (via Pten deletion) and inactivation of p53. By 9 months of age, over 75% of the compound mutant mice develop aggressive, undifferentiated thyroid tumors that evolve from pre-existing follicular hyperplasia and carcinoma. Expression of the Foxe1, Pax8, and Nkx2–1 transcription factors, as well as of the thyroid-specific genes Duox2, Tpo, Tg, Tshr, and Slc5a5 (Nis) is reduced to almost undetectable levels in the anaplastic tumors, resembling the significant deregulation found in human ATC. Strikingly, the undifferentiated areas of all the tumors analyzed lose the expression of the epithelial marker E-cadherin, acquire the expression of the mesenchymal marker Vimentin, and display high levels of phosphorylated Smad2, strongly suggesting that elevated Tgf-β signaling contributes to the establishment and maintenance of EMT (epithelial-mesenchymal transition). Furthermore, similar to the human tumors, [Pten, p53]thyr−/− cells and tumors undergo the glycolytic switch known as Warburg effect. They display an up-regulation in the expression of Hexokinase II, Pyruvate Kinase M2, and Hypoxia-inducible factor 1α, and an increase in the amount of lactate levels. ATCs show an increase in glucose uptake by positron emission tomography (PET) and established cell lines derived from these tumors exhibit a high sensitivity to the therapeutic use of glycolytic inhibitors such as 3-bromopyruvate and 2-deoxyglucose, which synergize with standard chemotherapy. Taken together, this model represents a novel, powerful tool to understand the biology of human thyroid anaplastic carcinomas, and provide a compelling rationale for targeting glycolysis to increase chemotherapy response in ATC patients. The elucidation of this process will lead to innovative targeted approaches to selectively disrupt tumor progression, while preserving normal metabolism in non mutated cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B138.
Computing optimal low-rank matrix approximations for image processing

In this work, we describe a new framework for solving inverse problems, where training data is used, as a substitute for the forward model, to compute an optimal low-rank regularized inverse matrix directly, allowing for very fast computation of a regularized solution. An empirical Bayes risk minimization framework will be used to incorporate training data and to formulate the problem of computing an optimal low-rank regularized inverse matrix. We describe some theoretical results that motivate the development of numerical methods for computing an optimal low-rank regularized inverse matrix and demonstrate our approach on examples from image deconvolution.
The Effect of Pulley Reconstruction on Maximum Flexion, Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation.

Purpose The purpose of this experiment was to determine the effect of A2 pulley reconstruction on gliding coefficient (GC), bowstringing, and proximal interphalangeal (PIP) joint maximum flexion angle after zone II repair of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) lacerations.
Simulation of models of enteric virus epidemics.

Abstract Various extensions of a stochastic model illustrating the spread of virus epidemics have been simulated. As assumptions and hypotheses concerning the basic model have been added and tested, the computer programs designed to run the simulation have increased in complexity. With this increase it has been necessary to reduce the amount of time and effort involved in setting up computer runs. Default parametric values, alphanumeric coded control cards, different levels of trace options, and simplified summaries have enabled these model extensions. Studies have been conducted on the effects of varying vaccination schedules, contact rates, the interference phenomenon and population composition. Future models have been defined to investigate more complicated transfer patterns and withdrawal from population mixing of those cases in whom illness may result from infection, as for influenza. These studies have been of value to epidemiologists and have encouraged the continuing design of alternate models of a more specific and complex nature.
Reversibility of the temperature-dependent opacity of nonfat mozzarella cheese.

Abstract Salted and unsalted nonfat mozzarella cheese was made by direct acidification and stored at 4°C over 60 d. Changes in cheese opacity were measured by using reflectance L* values while the cheese was heated from 10 to 90°C, then cooled to 10°C, and reheated to 90°C. A characteristic opacity transition temperature (T OP ) was obtained for each cheese. Both salt content and storage time influenced T OP . Opacity during heating, cooling, and reheating formed a hysteresis. At d 1, the unsalted cheese became opaque when heated to 20°C, but the salted cheese required heating to 40°C. As the salted cheese was aged, its T OP increased so that by 60 d the cheese did not become opaque until it was heated to 70°C.
Strong Electronic Interaction between Two Dimolybdenum Units Linked by a Tetraazatetracene

The large rigid dianion fluoflavinate, C14H8N42-, consisting of four fused and planar six-membered rings with four nitrogen donor atoms, has been used to link two metal-to-metal bonded and redox-active Mo2n+ units which are each locally bridged by three additional groups, collectively denoted [Mo2]. In 1, the [Mo2] units are Mo2(DAniF)3 (DAniF = N,N‘-di-p-anisylformamidinate), and in 5, they are trans-Mo2(DAniF)2(O2CCH3) groups. These [Mo2](fluoflavinate)[Mo2] compounds show three reversible one-electron oxidation steps, one more than all other [Mo2](linker)[Mo2] species known to date. The first two redox processes are metal-based, and the third one has been assigned to a ligand oxidation by comparison to that of paddlewheel compound 4 which contains only one dimolybdenum unit with a monoanionic fluoflavinate ligand. Chemical oxidations of 1 produce the singly- and doubly-oxidized species 2 and 3, respectively. All compounds have been characterized by X-ray crystallography and, as appropriate, by various ...
ω-3 polyunsaturated fatty acids-derived lipid metabolites on angiogenesis, inflammation and cancer

Epidemiological and pre-clinical studies support the anti-tumor effects of ω-3 PUFAs; however, the results from human trials are mixed, making it difficult to provide dietary guidelines or recommendations of ω-3 PUFAs for disease prevention or treatment. Understanding the molecular mechanisms by which ω-3 PUFAs inhibit cancer could lead to better nutritional paradigms and human trials to clarify their health effects. The ω-3 PUFAs exert their biological activities mainly through the formation of bioactive lipid metabolites. Here we discuss the biology of cyclooxygenase, lipoxygenase and cytochrome P450 enzymes-derived ω-3-series lipid metabolites on angiogenesis, inflammation and cancer.
Effect of cimetidine on delayed hypersensitivity

Abstract Histamine influences the expression of delayed hypersensitivity skin tests through the histamine type 2 (H-2) receptor. Previous work has demonstrated this effect in vivo by local injection of H-2 receptor antagonists into the skin test site; and by incorporation of these agents into the culture media in in vitro studies. Cimetidine, a H-2 receptor antagonist, was given to guinea pigs before and during the period of sensitization to a hapten-protein conjugate. Delayed hypersensitivity was studied by skin testing and production of migration inhibitory factor (MIF). Increased MIF production was demonstrated in vitro ; but no effect was noted in vivo . No good explanation exists for the failure to enhance skin test reactivity; but the presence of H-1 and H-2 receptors in vascular smooth muscle in the skin may explain skin test reactivity. Lymphocyte production of MIF is regulated by H-2 receptors on sensitized lymphocytes.
A PKM2 signature in the failing heart

A salient feature of the failing heart is metabolic remodeling towards predominant glucose metabolism and activation of the fetal gene program. Sunitinib is a multitargeted receptor tyrosine kinase inhibitor used for the treatment of highly vascularized tumors. In diabetic patients, sunitinib significantly decreases blood glucose. However, a considerable proportion of sunitinib-treated patients develop cardiac dysfunction or failure. We asked whether sunitinib treatment results in shift towards glycolysis in the heart. Glucose uptake by the heart was increased fivefold in mice treated with sunitinib. Transcript analysis by qPCR revealed an induction of genes associated with glycolysis and reactivation of the fetal gene program. Additionally, we observed a shift in the enzyme pyruvate kinase from the adult M1 (PKM1) isoform to the fetal M2 (PKM2) isoform, a hallmark of the Warburg Effect. This novel observation led us to examine whether a similar shift occurs in human heart failure. Examination of tissue from patients with heart failure similarly displayed an induction of PKM2. Moreover, this phenomenon was partially reversed following mechanical unloading. We propose that pyruvate kinase isoform switching represents a novel feature of the fetal gene program in the failing heart.
Propionate Inhibits Hepatocyte Lipid Synthesis

Oat bran lowers serum cholesterol in animals and humans. Propionate, a short-chain fatty acid produced by colonic bacterial fermentation of soluble fiber, is a potential mediator of this action. We tested the effect of propionate on hepatocyte lipid synthesis in rats using [1-14C]acetate, 3H2O, and [2-14C]mevalonate as precursors. Propionate produced a statistically significant inhibition of cholesterol biosynthesis from [1-14C]acetate at a concentration of 1.0 mM and from 3H2O and [2-14C]mevalonate at concentrations of 2.5 mM. Propionate also produced a significant inhibition of fatty acid biosynthesis at concentrations of 2.5 mM using [1-14C]acetate as a precursor. The demonstration of propionate-mediated inhibition of cholesterol and fatty acid biosynthesis at these concentrations suggests that propionate may inhibit cholesterol and fatty acid biosynthesis in vivo and may mediate in part the hypolipidemic effects of soluble dietary fiber. Further studies are needed to clarify this action of propionate and to establish the exact mechanisms by which the inhibition occurs.
Postsynaptic signaling networks: Cellular cogwheels underlying long-term plasticity

Learning depends on positive or negative changes in synaptic transmission that are synapse-specific and sustained. Synaptic signals can be directly measured and respond to certain kinds of stimulation by becoming persistently enhanced (long-term potentiation, LTP) or decreased (long-term depression, LTD). Studying LTP and LTD opens a window on to the molecular mechanisms of memory. Although changes in both pre- and postsynaptic strength have been implicated in LTP and LTD, most attention has been focused on changes in postsynaptic glutamate receptor density. This is controlled by intracellular Ca(2+) ions via a network of signaling molecules. Changes in postsynaptic Ca(2+) concentration depend on the coincidence of appropriate synaptic signals, as is found in learning situations. The long-term persistence of LTP and LTD requires gene transcription and translation. It is posited that local translation at the synapse, in a self-sustaining manner, mediates the persistence of long-term changes despite constant turnover of the synaptic components.
An analysis of urban tree communities using Landsat Thematic Mapper data

Abstract Highly diverse tree communities of natural and planted forests are found in distinct microhabitats in urban settings. The purpose of this paper is to examine the possibility of locating and analyzing urban tree communities at a relatively low cost, using the new satellite imagery data collected from the U.S. Landsat Thematic Mapper (TM). Mobile, Alabama, is the study area. A multichannel TM data set of the study area is analyzed using the hierarchical clustering and minimum-distance classification procedures of the Earth Resources Laboratory Applications Software. The data analysis, at one detail level chosen for this study, reveals 23 spectral classes of trees. Ground checking has verified that the 23 spectral classes include 8 distinct tree communities of remnant natural forests and 15, of cultivated residential forests. These tree communities, developed naturally or planted, vary with species composition, age, density, crown closure, and vertical structure. The detailed analysis of urban forests using TM data assists foresters and planners in the modification or maintenance of urban trees suited to local site conditions. It provides a database for achieving a balanced forest structure and composition that will promote neighborhood planning and the health, safety, and welfare of urban residents. The study has also disclosed the potential of TM data in creating or updating economic geographic information systems of tree communities in metropolitan areas to hasten urban forestry management and comparative research.
Synthesis of Block Copolymers Containing a Main Chain Polymeric NLO Segment

A novel poly-4-vinylpyridine-b-PNLO (nonlinear optical material)-b-polystyrene-b-poly(4-vinylphenol) tetrablock copolymer (P4VP-b-PNLO-b-PS-b-PVPh) was synthesized containing an NLO polymeric segment prepared by step polymerization. The tetrablock copolymer is designed to form an asymmetric lamellar structure by self-assembly prompted by the interactions between the donor and acceptor blocks which are expected to help to align the dipole moments of PNLO block into one direction. The synthesis was carried out by reaction of a P4VP-b-PNLO−Ph−NH2 block copolymer containing an aniline end group with a poly(4-tert-butyldimethylsiloxy)styrene-b-PS−CO2H (PBDMSS-b-PS−COOH) diblock copolymer containing a tert-butyldimethylsilyl-protected polyvinylphenol endowed with a carboxylic end group in the presence of diphenylphosphoryl azide (DPPA) in N,N-dimethylacetamide. After the formation of the P4VP-b-PNLO−PhNH−CO−PS-b-PBDMSS tetrablock copolymer the PVPh block was obtained by deprotection of tert-butyldimethylsilyl g...
PROTEIN FOLDING STABILITY CAN DETERMINE THE EFFICIENCY OF ESCAPE FROM ENDOPLASMIC RETICULUM QUALITY CONTROL

A fraction of each secreted protein is retained and degraded by the endoplasmic reticulum (ER) quality control apparatus that restricts export to correctly folded proteins. The intrinsic biophysical attributes that determine efficiency of escape from this proofreading process have been examined by expressing mutants of bovine pancreatic trypsin inhibitor (BPTI) in yeast. Secretion efficiency is strongly correlated with thermodynamic stability for a series of six point mutations of BPTI. No correlation of secretion efficiency with either oxidative folding or refolding rates in vitro is found; both the rapidly folded Y35L BPTI mutant and the slowly unfolded G36D BPTI mutant exhibit low secretion efficiency. Elimination of cysteines 14 and 38 by mutagenesis does not increase secretion efficiency, indicating that intramolecular thiol/disulfide rearrangements are not primarily responsible for retention and degradation of destabilized BPTI variants. Mutant yeast strains with diminished ER-associated degradation do not secrete BPTI more efficiently, indicating that retention and degradation are separable processes. These data support a model for ER quality control, wherein protein folding is functionally reversible and the relative rates of folding, unfolding, vesicular export, and retention determine secretion efficiency.
Effect of Sustained Isometric Handgrip Exercise on Left Ventricular Performance

Sustained isometric handgrip exercise was studied in 28 patients, 19 with and nine without catheterization evidence of heart disease. Significant increases occurred in left ventricular systolic and left ventricular end-diastolic pressures (LVEDP), heart rate, cardiac output, and cardiac index, with decreases in stroke volume and stroke index. When control and abnormal groups were compared, no differences could be demonstrated in systolic pressure or heart rate increases. However, the LVEDP increase in the abnormal subjects (9.7 ± 1.7) was significantly (P < 0.01) higher than in the controls (2.1 ± 0.7). In addition, cardiac index rose significantly (P < 0.025) in the controls (0.8 ± 0.2), but not (P < 0.1) in the abnormal subjects (0.2 ± 0.1). Conversely, there was a significant fall in stroke index in the abnormal (P < 0.005) but not in the control (P < 0.4) group. When work or stroke-work index-LVEDP relations were compared, the controls uniformly exhibited steep curves, whereas abnormal patients demons...
Spatiotemporal Mapping Of Fluorescence Parameters In Cells Treated With Toxic Chemicals: The Cell's Detoxification Apparatus

We have used a grating microspectrofluorometer equipped with phase and fluorescence microscopy to study the intracellular localization and processing of fluorescent compounds that are not part of the natural cell chemistry (xenobiotics) and of fluorescent carcinogens. Our topographic and spectral observations, in conjunction with ultrastructural analysis, lead to the hypothesis of a dynamically organized multiorganelle complex involved in the cell's detoxification processes and possible protection of the cell's genetic apparatus. Our studies with quinacrine derivatives and benzo(a)pyrene suggest that the organelle complex involves the endoplasmic reticulum, the Golgi apparatus, the lysosomes, and the nuclear membrane, with a fine microchannel network interconnecting the different organelles. We have indications that there is not only a trapping of fluorescent carcinogens in the cytoplasmic components of the complex but also a possible "nuclear pump" (powered by the substrates of the hexose monophosphate shunt pathway) involved in ejection of xenobiotics from the nucleus. The instrumental performance allows the in situ pixel-by-pixel study of extranuclear and nuclear energy metabolism related to these processes in parallel to the blue and red spectral shifts associated with metabolites of fluorescent carcinogens. Recording of fluorescence emission spectra at different excitation wavelengths in human fibroblasts and rat liver cells allows the application of multivariate statistical methods to analyze multicomponent spectra. Elucidation of mechanisms involved in the organization and activity of the organelle complex is relevant to the interpretation of drug sensitivity or resistance and should result in better targeting of cancer chemotherapeutics and gene modifiers toward their expected sites of action.
Perfectly Matched Layer as an Absorbing Boundary Condition for the Linearized Euler Equations in Open and Ducted Domains

Recently, perfectly matched layer (PML) as an absorbing boundary condition has found widespread applications. The idea was first introduced by Berenger for electromagnetic waves computations. In this paper, it is shown that the PML equations for the linearized Euler equations support unstable solutions when the mean flow has a component normal to the layer. To suppress such unstable solutions so as to render the PML concept useful for this class of problems, it is proposed that artificial selective damping terms be added to the discretized PML equations. It is demonstrated that with a proper choice of artificial mesh Reynolds number, the PML equations can be made stable. Numerical examples are provided to illustrate that the stabilized PML performs well as an absorbing boundary condition. In a ducted environment, the wave modes are dispersive. It will be shown that in the presence of a mean flow the group velocity and phase velocity of these modes can have opposite signs. This results in a band of transmitted waves in the PML to be spatially amplifying instead of evanescent. Thus in a confined environment, PML may not be suitable as an absorbing boundary condition unless there is no mean flow.
On the reliability of the extreme score

Under the assumption of normality, a formula is derived for the reliability of the maximum score. It is shown that the maximum score is more reliable than each of the single observations, but less reliable than their composite score.
SU‐FF‐T‐175: Dosimetric Effect of Rotational Variation On Helical Tomotherapy Treatment Plans

Purpose: Helical tomotherapy is subject to rotational output variation during treatment delivery. The purpose of this study is to evaluate the dosimetric effects of the rotational variation using recalculated treatment plans which include a rotational variation.Method and Materials: In order to assess the rotational output variation, the monitor chamber signal was extracted from delivered treatment data archives and analyzed. The rotational variation was then modeled and incorporated back into the treatment plan sinogram by adjusting the leaf opening times for each projection. The modified treatment plans were then calculated using a research version of the planned adaptive treatment planningsoftware from TomoTherapy, Inc. Two treatment plans, one head and neck and one prostate, were evaluated in this study. Treatment plans were recalculated with an observed rotational variation of ±2 % and a hypothetical variation of ±10 % for comparison to the original calculated treatment plans. Results: The rotational variation from delivered treatments was found to follow a sinusoidal shape with a period equal to one gantry rotation and a magnitude of about ±2% on average. For a rotational variation of ±2%, the D95 for the target volumes and the D50 for critical structures were found to be different from the original plan by less than 0.26% for the recalculated treatment plans. For a hypothetical rotational variation of ±10%, the difference from the original was less than 0.5% for the D95 for target volumes and 1.4% for the D50 of critical structures. Conclusion: The rotational variation for delivered helical tomotherapy treatments was found to be on the order of ±2%. For this observed rotational variation, a negligible dosimetric effect on calculated helical tomotherapy treatment plans was found. Conflict of Interest: Our group holds a research grant from TomoTherapy, Inc.
Can a secondary isotope effect be larger than a primary

Whither Physical Organic Chemistry? Wither? Or Wider? Charles L. Perrin Department of Chemistry, University of California—San Diego La Jolla, CA 92093-0358 USA cperrin@ucsd.edu Abstract A personal view of the field of physical organic chemistry (broadly construed), its history, it current status, and what it may become in the future. Keywords molecular structure, chemical reactivity, transition state, methodology, definition of terms, applications History of Physical Organic Chemistry What is physical organic chemistry? One (circular) definition of physical organic chemistry is that it is the area of research that physical organic chemists work in. My definition is broader, including many aspects that might be excluded from organic chemistry. Physical organic chemistry is the study of whatever is interesting about the relationship between molecular structure and chemical reactions. In my opinion physical organic chemistry represents the intellectual basis of organic chemistry. It asks (and answers!) fundamental questions about how chemical substances behave, and it rationalizes that behavior. Louis Hammett had supposed that it was possible to make quantitative the general principle of organic chemistry that like changes in structure produce like changes in reactivity. 1
Fundamental regions of superspace.

We consider the fundamental region for the space of spatial metrics over ({ital d}{minus}1)-dimensional tori in order to normalize the universal wave function.
Biosynthesis of the β-Amino Acid Moiety of the Enediyne Antitumor Antibiotic C-1027 Featuring β-Amino Acyl-S-carrier Protein Intermediates

The enediyne antitumor antibiotic C-1027 chromoprotein is produced by Streptomyces globisporus. The biosynthesis of the (S)-3-chloro-4,5-dihydroxy-beta-phenylalanine moiety (boxed) of the C-1027 chromophore (1) from l-tyrosine (3) and its incorporation into 1 are catalyzed by six enzymes: SgcC, SgcC1, SgcC2, SgcC3, SgcC4, ShcC5. In vivo and in vitro characterization of these enzymes delineated this pathway, unveiling a novel strategy for beta-amino acid modification featuring beta-amino acyl-S-carrier protein intermediates. These findings shed new light into beta-amino acid biosynthesis and present a new opportunity to engineer the C-1027 biosynthetic machinery for the production of novel analogues as exemplified by 20-deschloro-C-1027 (4), 20-deschro-22-deshydroxy-C-1027 (5), and 22-deshydroxy-C-1027 (6).
Preparation and assay of monohydroxy-eicosatetraenoic acids.

Abstract 5-, 8-, 9-, 11-, 12-, and 15-hydroxy-eicosatetraenoic acids (HETEs) were prepared from arachidonic acid by reaction with H2O2 in the presence of Cu2+ ions. They were separated by high-performance liquid chromatography on silica gel (μPorasil), using a linear solvent gradient from hexane to chloroform: only the 8- and 9-isomers were not resolved. Multi-milligram quantities of highly purified HETEs could be easily generated by this method, which thus provides a useful tool to study the biological activity of these compounds. Octadeuterated analogs of HETEs prepared from octadeuterated arachidonic acid by this procedure were suitable for use as internal standards in stable isotope dilution assays, by combined gas chromatography and mass spectrometry, with selected ion monitoring. The detection limit of the HETEs was less than 1 ng.
Probing the Flexibility of Large Conformational Changes in Protein Structures through Local Perturbations

Protein conformational changes and dynamic behavior are fundamental for such processes as catalysis, regulation, and substrate recognition. Although protein dynamics have been successfully explored in computer simulation, there is an intermediate-scale of motions that has proven difficult to simulate—the motion of individual segments or domains that move independently of the body the protein. Here, we introduce a molecular-dynamics perturbation method, the Rotamerically Induced Perturbation (RIP), which can generate large, coherent motions of structural elements in picoseconds by applying large torsional perturbations to individual sidechains. Despite the large-scale motions, secondary structure elements remain intact without the need for applying backbone positional restraints. Owing to its computational efficiency, RIP can be applied to every residue in a protein, producing a global map of deformability. This map is remarkably sparse, with the dominant sites of deformation generally found on the protein surface. The global map can be used to identify loops and helices that are less tightly bound to the protein and thus are likely sites of dynamic modulation that may have important functional consequences. Additionally, they identify individual residues that have the potential to drive large-scale coherent conformational change. Applying RIP to two well-studied proteins, Dihdydrofolate Reductase and Triosephosphate Isomerase, which possess functionally-relevant mobile loops that fluctuate on the microsecond/millisecond timescale, the RIP deformation map identifies and recapitulates the flexibility of these elements. In contrast, the RIP deformation map of α-lytic protease, a kinetically stable protein, results in a map with no significant deformations. In the N-terminal domain of HSP90, the RIP deformation map clearly identifies the ligand-binding lid as a highly flexible region capable of large conformational changes. In the Estrogen Receptor ligand-binding domain, the RIP deformation map is quite sparse except for one large conformational change involving Helix-12, which is the structural element that allosterically links ligand binding to receptor activation. RIP analysis has the potential to discover sites of functional conformational changes and the linchpin residues critical in determining these conformational states.
Phase calculation approaches for a multi-tier weak radio signal detection process with N simultaneous signals

This paper reviews the results of a generalized theoretical analysis of Tsui's phase measurement approach for detection of extremely weak radio signals to the situation in which there are N simultaneous signals, where one signal is strong, and N − 1 signals are weak. Applications to a multi-tier detection process for N = 2, N = 3, and N = 4 simultaneous signals are described. Signal parameters are extracted for the case of N = 2. This work has applications for electronic warfare receivers for detection and characterization of weak signals with unknown parameters.
Low-temperature spin spray deposited ferrite/piezoelectric thin film magnetoelectric heterostructures with strong magnetoelectric coupling

We report low-temperature spin spray deposited Fe3O4/ZnO thin film microwave magnetic/piezoelectric magnetoelectric heterostructures. A voltage induced effective ferromagnetic resonance field of 14 Oe was realized in Fe3O4/ZnO magnetoelectric (ME) heterostructures. Compared with most thin film magnetoelectric heterostructures prepared by high temperature (>600 °C) deposition methods, for example, pulsed laser deposition, molecular beam epitaxy, or sputtering, Fe3O4/ZnO ME heterostructures have much lower deposition temperature (<100 °C) at a much lower cost and less energy dissipation, which can be readily integrated in different integrated circuits.
Ptc1 and Ptc2 Transcripts Provide Distinct Readouts of Hedgehog Signaling Activity during Chick Embryogenesis

Hedgehog (Hh) signaling in vertebrates controls patterning and differentiation of a broad range of tissues during development. The Hh receptor Patched (Ptc) is a critical regulator of signaling, maintaining active repression of the pathway in the absence of stimulation, limiting excess diffusion of ligand, and providing an efficient negative feedback mechanism for fine-tuning the responsiveness of receiving cells. Two distinct Ptc genes have been isolated from several vertebrates. Here, we describe the cloning of a second Ptc gene from chick (Ptc2). We show that Ptc1 and Ptc2 are both upregulated at sites of active Hh signaling but that the expression patterns of these genes only partially overlap, thus providing distinct readouts of Hh pathway stimulation. We also show that chick Ptc2 is expressed in the posterior apical ectodermal ridge (AER) of the limb bud in a pattern similar to Fgf4 and that the induction of Ptc2 within the AER, like that of Fgf4, is mediated via antagonism of BMP signaling. The differential responsiveness of cells to Hh pathway stimulation (as marked by the differential induction of Ptc genes) suggests heterogeneity in the mechanisms by which Hh signals are transduced within different populations of receiving cells.
Hemodynamics of the Boston Scientific Lotus™ Valve: An In Vitro Study

Transcatheter Aortic Valve Replacement (TAVR) is currently used for patients with aortic valve disease at high risk for surgical intervention. The Lotus™ Valve system (Boston Scientific) is a novel repositionable TAVR with bovine pericardial leaflets and a Nitinol® frame, including miniature buckles for repositioning. A detailed characterization of the fluid flow environment in the vicinity of the buckles and the sinus regions will help identify regions of potential flow stagnation and thrombosis. A Lotus Valve was deployed in an in vitro left heart simulator, and the fluid flow through the valve was quantitatively characterized using particle image velocimetry. Three planes of high spatial resolution velocity data were obtained across the valve through the entire cardiac cycle at three stroke volumes (SV). The resulting velocity fields were processed to obtain Reynolds shear stresses (RSS), viscous shear stresses (VSS) and turbulent kinetic energy (TKE) fields. The Lotus Valve showed a central systolic jet at all three SV in the central plane. This jet caused a strong sinus vortex, which persisted through entire systole for all three SV. The location of the vortex was dependent on the SV through the valve. High VSS, RSS and TKE regions were observed at the edge of the systolic jet distal to the valve, however high velocities in these regions caused washout of fluid, which may prevent thrombus formation. The buckle region did not appear to significantly increase the potential for hemolysis of this valve. The Lotus Valve showed very good hemodynamic performance and no regions of stagnation were observed in the vicinity of the valve. These results compare favorably with flow characteristics through bioprosthetic aortic valve replacements, and suggest good clinical performance with this valve system.
Estimation of Real-Time Crash Risk: Are All Freeways Created Equal?

In-ground loop detectors have recently been used by many researchers to investigate the links with real-time crash risk and the traffic data. An issue that has been raised, but not explicitly addressed in these studies, is how the results from one freeway might transfer to another. A study was done to examine the relationship between crash risk and real-time traffic variables from a freeway corridor (eastbound I-4 in Orlando, Florida) and then to apply the models to three other freeway corridors (westbound I-4 and northbound and southbound I-95). Traffic data used in the study were collected with loop detectors as well as radar detectors already installed on these freeways. The traffic information was collected for crash as well as random noncrash cases so that a binary classification approach could be adopted. The random forest-based models provided a list of significant variables based on the average reduction in the Gini indices to the overall forest classification. The periods between 5 and 10 min bef...
Structure and properties of organosilane primers for adhesive bonding

Abstract Reflection—absorption infrared spectroscopy was used to determine the structure of films formed by the adsorption of γ-aminopropyltriethoxysilane (γ-APS) onto iron mirrors from aqueous solutions. Films formed at the natural pH of 1% aqueous solutions were composed of oligomers characterized by infrared bands near 1550, 1470 and 1130 cm-1 while films formed at pH values less than about 9.0 were composed of polysiloxanes characterized by bands near 1600, 1500 and 1135 cm-1. The polysiloxanes formed at low pH values were much more effective as primers for improving the hydrothermal stability of iron/epoxy lap joints than the oligomers obtained at high pH values. Joints prepared from substrates primed with γ-APS at pH = 8.0 retained about 70% of their strength after immersion for 60 days in water at 60°C while those prepared from substrates primed at pH = 10.4 retained only about 50% of their strength. By comparison, joints prepared from unprimed substrates retained only about 25% of their strength after such exposure.
The effect of human olfactory biopsy on olfaction: A preliminary report

Normal human olfactory function is subject to a wide variety of factors. Although biopsy of human olfactory neuroepithelium has been reported by several researchers, there are no studies which have evaluated the effect of this procedure on olfactory function. In this retrospective study, we sought to determine if tissue removal from the olfactory cleft has an adverse influence on the sense of smell. Nineteen subjects underwent bilateral olfactory testing and subsequent endoscopic olfactory mucosal biopsy. All subjects were retested 6 weeks to 1 year after olfactory neuroepithelial biopsy. No statistical difference was found between olfactory tests performed before or after biopsy. These data suggest that biopsy of human olfactory neuroepithelium has no discernible adverse effect on the ability to smell.
Validity of the Missouri Children's Picture Series as a Predictor of Childhood Sleep Disturbances

In view of recent findings in a retrospective study by two of the authors, the present research was designed to systematically assess the validity of the Missouri Children's Picture Series sleep disturbances scale. Study I compared groups of restless sleepers and nocturnal enuretics with matched cohorts attending a summer residential program for children with communication-related disorders. Study II examined the relation of two MCPS scales to parent reports of corresponding problems, using a multitrait-multimethod matrix, individual correlations, and cluster analysis. Neither study provided convincing evidence for the validity of the sleep disturbance scale.
Can tissue Doppler echocardiography detect subclinical myocardial dysfunction in patients with diabetes

Can tissue Doppler echocardiography detect subclinical myocardial dysfunction in patients with diabetes?
Delinquency and Adolescent Self-Conceptions: A Study of the Personal Relevance of Infraction

This study deals with the “personal relevance of infraction” in variable sociocultural contexts by examining the association between delinquency and adolescent self-conceptions among junior and senior high school students differentiated on the basis of race and status. Using questionnaire data and official police records, official delinquent evaluations and personal delinquent evaluations were found to be positively related. However, the strength of the relationship was found to vary between blacks and whites, by status among whites, and by attachment to the law among both blacks and whites. Moreover, while delinquents tend to be lower in self-esteem than non-delinquents, this relationship was found to vary as well. Delinquents and non-delinquents differ most among middle-to-upper status blacks and least among low status blacks. Finally, attachment to parents conditioned the relationship at each status level.