cssi/SciSciGPT-SciSciNet huggingface dataset:
Autocrine ligand binding to cell receptors. Mathematical analysis of competition by solution "decoys"

Autocrine ligands have been demonstrated to regulate cell proliferation, cell adhesion, and cell migration in a number of different systems and are believed to be one of the underlying causes of malignant cell transformation. Binding of these ligands to their cellular receptors can be compromised by diffusive transport of ligand away from the secreting cell. Exogenous addition of antibodies or solution receptors capable of competing with cellular receptors for these autocrine ligands has been proposed as a means of inhibiting autocrine-stimulated cell behavioral responses. Such "decoys" complicate cellular binding by offering alternative binding targets, which may also be capable of aiding or abating transport of the ligand away from the cell surface. We present a mathematical model incorporating autocrine ligand production and the presence of competing cellular and solution receptors. We elucidate effects of key system parameters including ligand diffusion rate, binding rate constants, cell density, and secretion rate on the ability of solution receptors to inhibit cellular receptor binding. Both plated and suspension cell systems are considered. An approximate analytical expression relating the key parameters to the critical concentration of solution "decoys" required for inhibition is derived and compared to the numerical calculations. We find that in order to achieve essentially complete inhibition of surface receptor binding, the concentration of decoys may need to be as much as four to eight orders of magnitude greater than the equilibrium disociation constant for ligand binding to surface receptors.
Modeling the optical and electrical response of nanostructured III–V solar cells

Concentrator Photovoltaics (CPV) have emerged as a potential alternative energy source due to a favorable balance between cost and efficiency. In contrast to traditional flat panel systems, CPVs result in cheaper fabrication costs since a bulk of the pricey crystalline solar cell is replaced with less expensive light collection and concentrator materials. However, in order to remain competitive with other energy technologies, CPV systems require core solar cells with both high efficiencies and low temperature coefficients. To address the previous need, incorporating nanostructures, such as quantum wells (QW) and quantum dots (QD), into III–V solar cells has been proposed as a potential route towards achieving efficiencies well exceeding 50% under concentration. Hence, vital to the design process of this particular class of solar cells is the ability to accurately calculate nanostructure properties critical to the operation of CPV devices. Here, we have developed a modeling routine using the physics based software Crosslight to systematically study how quantum effects influence the performance of photovoltaics. In particular, this methodology can be applied to study how nanoscale variables, including size, shape and material compositions, can be used to tailor the electrical and optical properties at the device level. Finally, macro-level engineering of the nanostructures, such as the number of stacked layers as well as the position of these structures within the device, is explored in optimizing the overall device response
A soluble neuronal factor alters contractile function of ventricular myocytes without effect on troponin T isoform expression.

Objective: The purpose of this investigation was to establish a model system to facilitate identification of the sympathetic neuronal factor(s) that promotes improved contractility in neonatal cardiac myocytes. Conditioned medium from PC12 cells with sympathetic phenotype served as the source of the neuronal factor. Methods: Contraction frequency, amplitude and velocity of cultured neonatal rat cardiac myocytes were measured by online video analysis. Interventions included in vitro sympathetic innervation, exposure to PC12 conditioned medium, neurotransmitters and antagonists. Metabolic activity was assayed by 2-deoxyglucose uptake. Troponin T isoform expression was analyzed by SDS–polyacrylamide gel electrophoresis. Results: Medium conditioned by neuronal PC12 cells induced contractility changes similar to those induced by in vitro sympathetic innervation. These effects of PC12 conditioned medium and innervation were not suppressed by adrenergic or muscarinic antagonists nor reproduced by neuropeptide Y or somatostatin. Neuronal PC12 conditioned medium but not chromaffin PC12 conditioned medium, increased metabolic activity of the myocytes as detected by [3H]-2-deoxyglucose, indicating that the effect was specific to the neuronal PC12 cells. The in vitro switch of troponin T isoform expression was not altered by exposure to PC12 conditioned medium. Conclusions: Increased contractile function induced by sympathetic innervation is reproduced by PC12 conditioned medium, but neither is mediated by sympathetic or muscarinic neurotransmitters. Troponin T isoform expression is not related to the contractility changes. This model system will allow identification of the factor(s).
Prehistoric Sea Turtle Hunting on the Pacific Coast of Mexico

Archaeological sites on the west coast of Mexico provide long-term records of human predation on sea turtle populations. These large reptiles, valuable for their meat, eggs, shell, oil, and skin, a...
Narrations of Race in STEM Research Settings: Identity Formation and Its Discontents.

This paper discusses conceptions of identity in relation to science education and presents material from a series of interviews and focus groups with graduate students in science and technology. Given difficulties in retention and levels of significant participation by minority students indicated by aggregate data, the issue of race, as it informs critical interactions at a majority research university, is explored in terms of its effects on identity formation. It is argued that we need to look at “real-time” science to see how subtle interactions affect minority graduate students. These interactions reveal how identity is established through the positioning inside or outside of the laboratory culture. Three themes were explored regarding the tensions of identity formation in the context of race and science education: (1) the issue of isolation, marginalization, and invisibility; (2) being valued through recognition of one's contributions to the community of scientists; and (3) reading race as an additional burden for minority students. Two participants' stories and their positioning as outsiders are explored in detail. The authors contrast building an identity as a scientist through one's educational experiences against being positioned as the “only one” representing his or her race at a primarily White institution. © 2008 Wiley Periodicals, Inc. Sci Ed93: 485–510, 2009
The Effects of Surface Chemical Interactions on the Properties of Filler-Reinforced Rubbers

Abstract 1. Heat treatment of carbon black-rubber mixtures is a method of “in process” polymer grafting which gives a definite improvement in the dynamic properties of vulcanizates. 2. The heat treatment process can be more effective if chemical promoters are used. These chemical promoters function as coupling agents between filler surface and rubber. 3. With very unreactive butyl rubber an effective interaction is produced both by the addition of chemical promoters and by the use of specially active surface-modified carbon black. 4. In normal unsaturated rubbers, surface modifications of carbon black with a wide variety of groups has shown only minimal effects on rubber-reinforcing ability. Halogenated blacks have a pronounced effect on vulcanization kinetics, giving cured vulcanizates of high crosslink density. 5. Carbon black surfaces can be deactivated by calcining at high temperatures. The loss of surface-bound hydrogen may not account for this loss in surface activity. 6. Grafting of polymers to the...
EMDR 12 years after its introduction: past and future research

Eye Movement Desensitization and Reprocessing (EMDR) was one of the first treatments of posttraumatic stress disorder (PTSD) to be evaluated in controlled research and has to date been empirically supported by 13 such studies. This article reviews the historical context and empirical research of EMDR over the past dozen years. Historically, EMDR's name has caused confusion in that "desensitization" is considered to be only a by-product of reprocessing and because the eye movement component of EMDR is only one form of dual stimulation to be successfully used in this integrative approach. Research is needed to determine the comparative efficacy of EMDR relative to cognitive-behavioral treatments of PTSD. However, this has been hampered by the lack of independent replication studies of the latter treatments. Current component analyses of EMDR have failed to effectively evaluate the relative weighting of its procedures. Parameters for future research and the testing of protocols for diverse disorders are suggested.
Biosynthesis of canavaninosuccinic acid from canavanine and fumarate in kidney

Abstract An enzyme preparation obtained by ammonium sulfate fractionation of an extract of acetone-dried hog kidney was found to catalyze the synthesis of canavaninosuccinic acid from canavanine and fumarate. With kidney enzyme, arginine competitively inhibits the formation of canavaninosuccinate from canavanine, while canavanine competitively inhibits the formation of argininosuccinate from arginine. It is concluded that the same enzyme, argininosuccinase, catalyzes both reactions. Because of the unusual ON bond present in canavaninosuccinate, it was possible to confirm the structure previously assigned to this compound by a single degradative reaction, catalytic hydrogenolysis with palladium black and hydrogen gas. The products of this reaction were identified as homoserine and guanidinosuccinic acid. In contradiction to published reports, canavanine was found to be catalytically hydrogenolyzed under the same conditions (neutral pH, room temperature, and atmospheric pressure) to form homoserine and guanidine, with the uptake of one mole of hydrogen per mole of canavanine. On paper chromatograms, it was found that an alkaline ferricyanide-nitroprusside spray was useful in identifying certain of the above compounds. With this reagent canavanine and canavaninosuccinate give bluish violet spots; arginine, argininosuccinate, and guanidinosuccinate give red spots; cyclized argininosuccinate and cyclized guanidinosuccinate give blue spots; and guanidine gives an orange spot.
Daily life cardiac ischaemia. Should it be treated

Daily life cardiac ischaemia is defined as reversible myocardial cellular hypoxia that occurs during activities of daily living, without artificial provocation. Most of these daily life ischaemic episodes are not associated with symptoms. However, it is not practical to distinguish silent versus symptomatic daily life ischaemia as both are associated with haemodynamic abnormalities and future adverse outcomes. Daily life cardiac ischaemia is best detected using ambulatory electrocardiogram (ECG) monitoring; however, there are other diagnostic tools (e.g. exercise treadmill) that can be used. Once detected, the optimal therapy for daily life myocardial ischaemia has yet to be identified. However, it does appear that usual antianginal medications including nitrates, beta-blockers, calcium antagonists and antiplatelet drugs are effective in reducing the incidence and severity of daily life myocardial ischaemia. Medical therapy and revascularisation should be utilised to obliterate all episodes of daily life cardiac ischaemia to prevent future cardiac events. Moreover, the efficacy of the chosen therapeutic regimen for each patient should be documented with follow-up objective testing. The diagnosis and management of daily life myocardial ischaemia is continually evolving. Future research as well as economic considerations will shape future management strategies.
Experimental test of blind tip reconstruction for scanning probe microscopy

Determination of the tip geometry is a prerequisite to converting the scanning probe microscope (SPM) from a simple imaging instrument to a tool that can perform width measurements accurately. Recently we developed blind reconstruction, a method to characterize the SPM tip shape. In principle this method allows estimation of the tip shape from an image of a tip characterizer sample that need not be known independently. In this work, we compare blind reconstruction results to those obtained by scanning electron microscopy for two diamond stylus profiler tips, one of which has a gentle shape and the other a more complicated profile. Of the two comparisons, the poorer agreement is still better than 30 nm for parts of the tip within a several micrometer neighborhood of the apex. In both cases the differences are comparable to the combined standard uncertainties of the measurements. We estimate uncertainties from five sources, the most significant of which is the repeatability of the stylus profiling instrument. In a separate measurement we determine the geometry of a silicon nitride SPM tip. The measured radius, 4-fold symmetry, included angle, and tilt are all consistent with expectations for such a tip.
MOMENTARILY EXCESSIVE CONSTRUCTION AS THE BASIS FOR PROTOADAPTATION.

The concept that all individual organisms are perfectly matched to their environment is clearly a false idealization. Actually, for most individual organisms the structural and physiological capacities are likely to be excessive1 for the needs of any particular moment. In the present context, ''excessive construction" refers to excess capacity, but only in terms of the state of a single character of a particular individual at a particular instant in time. This concept has no implications about the perfection of matching of any population of a species to the particular biotope it currently inhabits. Obviously, natural selection does not "look" just at an organism's momentary utilization of each aspect of the phenotype, but at the requirements imposed on all phenotypic aspects of an individual throughout its life span. The "excess" does represent a paradox. Why should phenotypes be overdesigned? Statements that such overdesign represents a "factor of safety" (cf. Kummer, 1959) hardly explain its origin. In any case they imply technological planning or prescience and should probably be discouraged. Although excessive construction
Predictors of condom use in sexually active adolescents

Unprotected sexual intercourse places a substantial number of adolescents at risk for sexually transmitted disease (STD) and human immunodeficiency virus (HIV) infection. While the most effective means of preventing STD/HIV infection among sexually active adolescents is consistent condom use, little is known about the factors that influence their consistent use among adolescents. This study of adolescents (n = 1049, mean age = 16.2 years) found that of the 266 teens who recently became sexually active, only 29% reported using condoms consistently. Consistent condom use was more frequent in males, those with little history of risk behavior and those with stronger intentions to use condoms in the future. Fear and anxiety of HIV, attitudes about risks other than HIV, and other safe behavior intentions were not significantly related to consistent condom use. Although intentions and recent behavior were significantly related, a different group of factors was found to predict intention to use condoms (e.g., perception of condom use by friends, general impulsive attitudes). Identifying and understanding the factors that influence adolescent sexual behavior and intentions is important for developing maximally effective HIV education/prevention programs.
Hyperquantization of Feynman Amplitudes

A hyperquantization formalism is presented which employs an occupation-number representation for the set of all Feynman amplitudes. The relation between the amplitudes and the occupation number representation is quite similar to that between the Fock amplitudes and the occupation number representation commonly used in the theory of quantized fields. The differential equations for the Feynman amplitudes can be written and manipulated in a more compact form in this representation. Formal solutions of these equations are given and the connection with the $S$-matrix formalism is discussed.
Effect of Temperature on Absorption Rates of Drug Implants

The absorption rates of drug pellet implants have been shown to be temperature dependent in frogs. For neutral compounds the rate equation tested was ( R ¯ / A ¯ ) r = K r ⋅ D r ⋅ ( S s ) r / δ r , where ( R ¯ / A ¯ ) r is the mean absorption rate per mean area at a given temperature relative to that at 0°C., Kr is a constant, Dr is the relative diffusion coefficient, ( Ss ) r is the relative solubility of drug, and δr is the relative diffusion layer thickness. To minimize body movement, the frog, Rana pipiens , was paralyzed with 10 mg./Kg. of d -tubocurarine chloride. After temperature equilibrium was attained in a water or ice bath, a small incision into the dorsal lymph sac was made, and two preweighed pellets of sulfanilamide or acetanilid were introduced. The pellets were removed, dried, and reweighed. A plot of ( R ¯ / A ¯ ) r versus Dr ·( Ss ) r/δr yielded a straight line with a slope 1.09 for the two compounds.
Effect of Aromatic Hydrocarbons on Friction and Surface Coating Formation with Three Additives

The improved additive response associated with additional refining of lubricating oil base stocks has been partly attributed to aromatic hydrocarbon removal. The validity of this theory was investigated by following the changes in steel-on-steel friction that resulted from the addition of representative aromatic hydrocarbons to blends containing a chlorinated wax, a sulfurized terpene oil or didodecyl phosphite as additives. Although some added aromatics did affect friction and surface coating formation during the original testing, the effects were generally eliminated if the aromatic was percolated through silica gel prior to test. Studies indicated that the originally observed effects of aromatics were probably caused by aromatic oxidation products rather than the parent hydrocarbon. Presented as an American Society of Lubrication Engineers paper at the ASME/ASLE International Lubrication conference held in New York City, October 9–12, 1972
Some Effects of Negative Instances on the Formation of Simple Concepts

Smoke (1933) first suggested that the efficiency of concept formation might be affected by presenting instances of what a concept is not rather than instances of what it is. He did not, however, evaluate the amounts of information transmitted by these "nedative" and "positive" instances. Meaningful comparison of efficiency in dealing with instances must be based on the pocential of each type of instance to transmit information about a concept. If a negative instance provides only a slight amount of information relevanc to a concept, it could not be expected to be as effective for problem solution as a positive instance that provides a great deal of information. Tools for evaluating potential usefulness of different instances were proposed by Hovland (1952). If a problem involves an identifiable number of dimensions which may be relevant to the solution, and each dimension can assume a limited number of values, the number of possible concepts of a particular type can be listed. Each positive or negative instance presented to S eliminates some of these possibilities. The potential usefulness of an instance can be measured by the number of possible conceprs eliminated by its presentation. The positive or negative instances necessary to define a concept exactly and without redundancy can be listed. Hovland and Weiss (1953) compared the effectiveness of different combinations of positive and negarive instances in presentation of conjunctive concepts, using exactly the number of instances necessary to define the concept. They found thar problems defined by all positive inscances were more easily solved than those defined by all negative instances. Problems defined by a mixture of positive and negative instances were intermediate in difficulry. In general, positive instances transmit more information per instance in conjunctive concepts than do negative instances. The greater amount of information transmitted per positive instance may be important in ease of solution. The findings of Bruner, Goodnow, and Austin (1956) with disjunctive concepts suggest thar amount of information per instance is indeed important in ease of problem solution. With disjunctive conceprs, the informational value of positive and negative instances reverses, negative instances generally transmitting more information per instance. Here negative inscances result in more efficient problem solution. There would be no discrepancy between amounts of information trans'This investigation was suppozted by a Public Health Service research fellowship (MF12, 979), from the National Institute of Mental Health.
High angiotensin-converting enzyme activity in the neurohypophysis of Brattleboro rats

The activity of angiotensin-converting enzyme is significantly higher in the intermediate and posterior pituitary lobes of Brattleboro rats than in Long-Evans control rats. The high activity level was reversed by vasopressin treatment. Conversely, angiotensin-converting enzyme activity was significantly lower in the anterior pituitary of Brattleboro rats than in Long-Evans rats, and this activity level was not affected by vasopressin. these findings suggest an inverse relation between vasopressin and angiotensin systems in the posterior and intermediate lobes of the pituitary gland.
Current Perspectives on Curriculum Needs in Zoological Medicine

Advances have been made in expanding veterinary curricula to deliver basic key knowledge and skills necessary for provision of health care to captive and companion non-domestic or non-traditional species in the veterinary colleges of the United States and Canada. These advances were in large part facilitated by the deliberations and recommendations of the White Oak Accords. Though a five-year review of curricular opportunities at US and Canadian veterinary colleges shows that progress has been made in implementing the recommendations of the White Oak Accords, there remains room for improvement. The broadly comparative and health-maintenance basis of zoological medicine contributes critically to the potential for veterinary medicine to make important contributions to the concept of the integrated health of the planet. Emergence of key zoonotic and production-animal diseases derived from and within wildlife populations since 2000 has increased awareness worldwide of the importance of zoological medicine in protecting both production livestock and public health. These areas are addressed in elective curricula at colleges emerging as centers of excellence in zoological medicine, but it is critical that core curricula in zoological medicine at all schools be strengthened to include these important areas to prepare our DVM/VMD graduates to protect companion-animal, production-animal, and public health.
Radar cross section measurements of frequency selective terahertz retroreflectors

The radar cross section of spherical retroreflectors operating at terahertz frequencies is investigated. Several spherical retroreflectors with diameters ranging from 2 mm to 8 mm were fabricated and their radar cross section was measured at 100 GHz, 160 GHz, and 350 GHz. A frequency selective surface was applied to the retroreflectors to demonstrate proof of concept of narrow-band terahertz retroreflection.
Nonlinear Analysis of Unsteady Flows in Multistage Turbomachines Using Harmonic Balance

A harmonic balance technique for the analysis of two-dimensional linear (small-disturbance) and nonlinear unsteady flows in multistage turbomachines is presented. The present method uses a mixed time-domain/frequency-domain approach that allows one to compute the unsteady aerodynamic response of multistage machines to both blade vibration (the flutter problem) and wake interaction (the forced response problem). In general, the flowfield may have multiple excitation frequencies that are not integer multiples of each other, so that the unsteady flow is (sometimes) aperiodic in time. Using our approach, we model each blade row using a computational grid spanning a single blade passage. In each blade row, we store several subtime level solutions. For flows that are periodic in time, these subtime levels span a single time period. For aperiodic flows, the temporal period spanned by these subtime level solutions is sufficiently long to sample the relevant discrete frequencies contained in the aperiodic flow. In both cases, these subtime level solutions are related to each other through the time-derivative terms in the Euler or Navier-Stokes equations and boundary conditions; complex periodicity conditions connect the subtime levels within a blade passage, and interrow boundary conditions connect the solutions among blade rows. The resulting discretized equations, which are mathematically steady because time derivatives have been replaced by a pseudospectral operator in which the excitation frequencies appear as parameters, can be solved very efficiently using multigrid acceleration techniques. In this paper, we apply the technique to both flutter and wake-interaction problems and illustrate the influence of neighboring blade rows on the unsteady aerodynamic response of a blade row.
Optofluidic glucose sensor utilizing an epoxy-based, transparent dry film resist

An enzymatic, fluorescent glucose sensor was constructed with a novel epoxy-based, optically-transparent dry film resist (PerMX 3000 series, DuPont). This material was utilized as the main active material for fluidic structure and optical interrogation. This sensor was based on the enzymatic reaction of glucose oxidase (GOD) and utilized a ruthenium complex fluorophore as the reporting agent. Both the oxygen-sensitive ruthenium complex and GOD were incorporated into poly(ethylene glycol) (PEG)-based hydrogel materials, which were lithographically patterned and embedded inside the PerMX fluidic channel after wafer-bonding process. The optofluidic sensing platform with this embedded sensing elements exhibited a wide dynamic range of 0–20 mM (0–360 mg/dl) glucose with good sensitivity. This finding demonstrates the promise of PerMX-based fluidic systems as platforms for various optofluidic assays.
Retinopathy of prematurity in multiple-gestation pregnancies

Purpose To determine differences in incidence of retinopathy of prematurity between neonates of multiple-gestation and single-gestation pregnancies and to analyze differences in severity of retinopathy of prematurity among siblings of multiple-gestation pregnancies. Methods We reviewed the records of 149 neonates of multiple-gestation pregnancies and 691 single-gestation neonates screened for retinopathy of prematurity at one hospital from January 1, 1992, through December 31, 1995. The peak stage of retinopathy of prematurity was recorded for all infants. The multiple-gestation infants were then separated into concordant and discordant retinopathy of prematurity groups, with discordance defined as a difference of at least 2 stages of retinopathy of prematurity between siblings. Between siblings with discordant retinopathy of prematurity, multiple factors were compared. Results Retinopathy of prematurity was present in 69 (46%) of the multiple-gestation neonates. Retinopathy of prematurity was present in 312 (45%) of single-birth neonates. The percentage of multiple-gestation neonates with stages 1, 2, or 3 (prethreshold) or threshold retinopathy of prematurity was similar to that of single-gestation neonates. Stage 4 or 5 retinopathy of prematurity did not occur in either group. Conclusions There was no significant difference in stage of retinopathy of prematurity between infants of single-gestation pregnancies vs those of multiple-gestation pregnancies. The majority (84%) of infants of multiple-gestation pregnancies had concordant retinopathy of prematurity. In those infants with discordant disease, zygosity and postgestational factors other than lowest serum glucose were not related to severity of retinopathy of prematurity.
Kinetic Modeling and Simulation of the Selective Hydrogenation of the C3-Cut of a Thermal Cracking Unit

The kinetics of the gas phase selective hydrogenation of methyl acetylene (MA) and propadiene (PD) over a Pd/alumina catalyst were investigated in a fixed bed tubular reactor at temperatures 60−80 ...
The pseudoscalar nonet in generalized NJL models

Abstract The pseudoscalar nonet mass spectrum and vacuum decay constants are discussed using generalized Nambu-Jona-Lasinio models. It is shown that in the large N c limit the bulk parameters of the pseudoscalars follow from chiral symmetry alone and do not depend on the detailed choice of the various interaction terms. Overall, the results compare favourably with the data.
Establishment of Psyllaephagus parvus and P. perplexans as serendipitous biological control agents of Eucalyptus psyllids in southern California

The free-living lemon gum psyllid, Cryptoneossa triangula Taylor, and the lerp-forming spotted gum psyllid, Eucalyptolyma maideni Froggatt (Hemiptera: Psyllidae) are invasive pests of eucalypts in California. In 2007, Psyllaephagus parvus Riek (Hymenoptera: Encyrtidae) was discovered parasitizing spotted gum psyllids and Psyllaephagus perplexans Cockerell was collected from lemon gum psyllids. While neither parasitoid species was purposely introduced, presence of the parasitoids was significantly associated with reduced intensity and duration of population peaks for both psyllid species. Spring peaks were reduced more than fall peaks. We estimated minimum rates of parasitism from the ratio of mummies to live nymphs. Higher parasitism was recorded in coastal than inland locations during the spring, while parasitism was similar for coastal and inland populations in the fall. Logistic regression models suggest parasitoids were the determining factor of psyllid population densities, although physical parameters, such as irrigation, may affect psyllid or parasitoid populations.
A brief review of the biology of the oceanic squid, Symplectoteuthis oualaniensis (Lesson)

Abstract 1. 1. Our current knowledge of the squid, Symplectoteuthis oualaniensis , one of the organisms utilized to a large extent during the Alpha Helix Kona Expedition, is briefly reviewed.
Reactions of group IVB compounds with acyl fluorides

Abstract Derivatives of acyl fluorides can be readily prepared in high yields by reaction with Group IVB compounds. The reaction may be represented as where n =0-3, and, when M is Si, Y may be nitrogen, oxygen, sulfur, or halogen. When M is Ge or Sn the scope of the reaction is more limited, but oxygen and nitrogen derivatives may be prepared. These results are discussed on the basis of the energies of the bonds involved.
Cortical intercorrelations of frontal area volumes in schizophrenia.

Abstract Background: Abnormal regional volume intercorrelations between selected cortical areas in schizophrenia patients were previously reported in several MRI studies. Methods: A detailed analysis of frontal gray and white matter volume correlations with Brodmann's area volumes in the rest of the cortex was undertaken in normal subjects (n = 42) and patients with schizophrenia (n = 106), divided into good-outcome (n = 52) and poor-outcome (Kraepelinian; n = 54) subtypes. Results: Frontal gray matter volumes were correlated with temporal lobe volumes in schizophrenics but not in normal subjects. Some frontal–parietal and frontal–occipital correlations showed a similar pattern. In comparison to normal subjects, schizophrenia patients showed weaker or absent intercorrelations intrafrontally, specifically between left motor–premotor and eye-movement areas (4, 6, 8) and dorsolateral area 44, as well as between left areas 9 and 46 vs. area 24 (cingulate gyrus). Poor outcome among patients with schizophrenia was associated with weaker correlations between left frontal area 9 and both medial and lateral temporal cortices, as compared to normal subjects or good-outcome patients. Conclusions: There appears to be a structural component in the task or symptom-related dysfunctional interactions between the frontal and more posterior cortical regions with preferential pathological involvement of frontotemporal and more limited involvement of frontoparietal and fronto-occipital systems in schizophrenia. Impaired regional associations within the frontal lobe, between left motor–premotor and Broca's areas, may play a role in language processing deficits in schizophrenia, while frontocingulate disconnection may result in working memory disturbances. Poor outcome may be associated with more widespread disconnections between prefrontal vs. cingulate and temporal regions in the left hemisphere, consistent with a disruption along the course of the left cingulum or uncinate bundles.
Relaxation to native conformation of a bond-fluctuating protein chain with hydrophobic and polar nodes.

The conformation and dynamics of a protein chain with hydrophobic and polar nodes are examined by the bond-fluctuation model using Monte Carlo simulations on a cubic lattice. The minimal (nearest neighbor) interaction leads to standard (self-avoiding walk) conformation, i.e., the scaling of the radius of gyration ${R}_{g}$ with the molecular weight $N$ ${R}_{g}\ensuremath{\propto}{N}^{\ensuremath{\gamma}}$ with $\ensuremath{\gamma}\ensuremath{\simeq}3∕5$. Specific interactions with longer range and higher strength are needed to approach the native globular conformations with $\ensuremath{\gamma}l3∕5$. Relaxation into the globular ground state shows a weak power-law decay, i.e., ${R}_{g}\ensuremath{\propto}{t}^{\ensuremath{-}\ensuremath{\alpha}}$, $\ensuremath{\alpha}\ensuremath{\sim}0.06\char21{}0.12$.
Left Posterior Fascicular Block in Canine and Primate Hearts An Electrocardiographic Study

To determine the electrocardiographic consequences of experimentally produced left posterior fascicular block, electrocardiograms of three baboons and three dogs were recorded from extremity and chest leads, from an esophageal lead, and from atraumatic exploring epicardial leads both before and after left posterior fascicular block and again after right bundle-branch block. The following electrocardiographic changes were noted: In direct epicardial leads from sites overlying zones of delayed myocardial excitation (1) increased ratio of R to S; (2) later intrinsic deflection time; and (3) appearance or augmentation of the Q wave. These altered potentials also appeared as rotations of the mean spatial QRS electrical axis. The QRS duration increased slightly. The addition of RBBB produced a further delay in deflection time in epicardial leads from the RV and a further increase in QRS interval. The epicardial envelopment by the excitation process is portrayed in diagrams. These observations emphasize the need...
Rhythm and Beat: Re-evaluating Arabic Prosody in the Light of Mahri Oral Poetry

This article attempts to resolve ambiguities that surround the prosody of bedouin vernacular poetry by analysing poetic performance amongst the Mahra of Southeast Yemen. As speakers of one of the few, remaining indigenous languages of the Arabian Peninsula, the Mahra have preserved an oral poetic practice that is free from the influence of literate Arabic poetics, including its prescriptive metrical rules. At the same time, Mahri poetry bears close thematic similarities to Arabic nabaṭī poetry, indicating an overlapping history with shared pre-historic roots. Based on fieldwork conducted in al-Mahra between 2003 and 2004, this article revisits the question whether bedouin vernacular poetry follows a qualitative or a quantitative metric and explores what this binary conception of prosody reveals about the performance of early historic Arabic poetry.
Estrogen modifies stress response of catecholamine biosynthetic enzyme genes and cardiovascular system in ovariectomized female rats

Estrogen is likely involved in the gender specific differences in coping with stress. Activation of catecholamine (CA) biosynthetic enzyme gene expression in central and peripheral CA systems plays a key role in response to stress and in regulation of the cardiovascular system. Here we examined whether estradiol can modulate response of hypothalamic-pituitary-adrenal axis (HPA), gene expression of enzymes related to CA biosynthesis in several noradrenergic locations, tetrahydrobiopterin (BH4) concentration and blood pressure (BP) in response to immobilization stress (IMO) of ovariectomized female rats. Rats were injected with 25 mug/kg estradiol benzoate (EB) or sesame oil once daily for 16 days and subsequently exposed to two hours of IMO. The IMO triggered elevation in plasma ACTH was lessened in EB-pretreated animals. However, estradiol did not alter the IMO-elicited rise of tyrosine hydroxylase mRNA levels in adrenal medulla (AM) and in the nucleus of solitary track (NTS) compared with controls. The response of GTP cyclohydrolase I (GTPCH) mRNA in AM to IMO was also similar in both groups. Several responses to IMO in EB-treated rats were reversed. Instead of IMO-elicited elevation in dopamine beta-hydroxylase mRNA levels in the locus coeruleus, GTPCH mRNA and BH4 levels in the NTS, they were reduced by IMO. In a parallel experiment, BP was monitored during restraint stress. The elevation of BP in response to single or repeated restraint stress was sustained during 2 h in controls and reduced after 70 min stress in EB treated rats. One month after withdrawal of EB treatment, the BP response to restraint was similar to that of rats which never received EB. The results demonstrate that estrogen can modulate responses to stress affecting HPA axis, CA biosynthesis, in central and peripheral noradrenergic systems, and BP.
Characterization of BlsM, a nucleotide hydrolase involved in cytosine production for the biosynthesis of blasticidin S.

Biosynthesis of the antifungal agent blasticidin S in Streptomyces griseochromogenes requires the formation of free cytosine. The blsM gene in the blasticidin S gene cluster is predicted to encode a protein that has sequence homology with several nucleoside transferases. In vitro analysis of recombinant BlsM revealed that the enzyme functions as a nucleotide hydrolase and catalyzes the formation of free cytosine by using cytidine 5′-monophosphate (CMP) as the preferred substrate. Cytosine production was significantly lower with CDP, CTP, and dCMP as alternate substrates. BlsM was also observed to have low-level cytidine deaminase activity, converting cytidine and deoxycytidine to uridine and deoxyuridine, respectively. Point mutations were introduced in blsM at putative catalytic residues to generate three mutant enzymes, BlsM Ser98Asp, Glu104Ala, and Glu104Asp. All three mutants lost CMP hydrolysis activity, but the Ser98Asp mutant showed a modest increase in cytidine deaminase activity.
Career Choice Patterns and Behavior of Work-Bound Youth during Early Adolescence.

A national longitudinal database (NELS: 88-94, 1996) was used to examine the occupational aspiration patterns, vocational preparation, and work-related experiences of adolescents who were either work-bound or college-bound two years after their initial transition from high school to work or postsecondary education. Adolescents' career choice and behavior patterns were analyzed at two separate points. Grades 8 and 10 achievement profiles of work- and unemployment-bound youths were similar; both groups had significantly lower achievement scores than college-bound youths. Socioeconomic status (SES) had considerable influence on determining both occupational aspirations and postsecondary transition status. Two-thirds of all young adults who were work-bound or unemployed/out of the work force were in the lowest two SES groups. Adolescents in the highest SES were four times more likely to be college-bound. Educational aspiration was a more accurate predictor of postsecondary status than occupational aspiration. Work-bound youths did not engage in higher levels of school-based work preparation than college-bound peers. Occupational aspirations of college-bound youth were relatively stable over the two-year period (from Grade 8 to 10), while those of noncollege-bound youths were more volatile. The prestige levels of occupational aspirations, for all youth, were relatively established by early adolescence and did not change significantly over time.
Detection and characterization of atherosclerotic fibrous caps with T2-weighted MR.

PURPOSE: We assessed the performance of T2-weighted MR imaging in detecting atherosclerotic fibrous caps and in depicting their integrity. METHODS: Twenty atherosclerotic lesions removed by carotid endarterectomy were imaged on a 1.5-T system using T2-weighted spin-echo sequences. The MR images were reviewed independently by four blinded interpreters for fibrous caps and ruptures. The results obtained from the observers were then graded against histologic findings by using receiver-operating characteristic (ROC) curve analysis. RESULTS: The area under the ROC curve for fibrous cap detection was 0.80, indicating that T2-weighted MR imaging was a good but not definitively diagnostic test for detecting ex vivo fibrous caps. The ROC curve for fibrous cap characterization yielded an area of 0.75, indicating that T2-weighted MR imaging was a fair but not highly diagnostic test for depicting fibrous cap integrity. A definite reading for detection of fibrous caps or rupture was fairly specific (90% and 98%, respectively) but not very sensitive (37% and 12%, respectively). CONCLUSIONS: T2-weighted MR imaging of ex vivo atherosclerotic plaques aided in the detection and evaluation of fibrous caps. In both cases, MR imaging proved more useful for ruling out disease than for confirming its presence.
Secretory dynamics of leptin in adolescent girls with anorexia nervosa and healthy adolescents.

Ghrelin is an orexigenic peptide and a growth hormone (GH) secretagogue. Secretory dynamics of ghrelin have not been characterized in adolescents with anorexia nervosa (AN). We hypothesized that, compared with healthy adolescents, girls with AN would have increased ghrelin concentrations measured over 12 h of nocturnal sampling from increased basal and pulsatile secretion, and endogenous ghrelin would independently predict GH and cortisol. We examined ghrelin concentration and secretory dynamics in 22 girls with AN and 18 healthy adolescents 12-18 yr old. Associations between ghrelin, various hormones, and measures of insulin resistance were examined. On Cluster analysis, girls with AN had higher ghrelin concentrations than controls, including total area under the curve (AUC) (P = 0.002), nadir (P = 0.0006), and valley levels (P = 0.002). On deconvolution analysis, secretory burst amplitude (P = 0.03) and burst mass (P = 0.04) were higher in AN, resulting in higher pulsatile (P = 0.05) and total ghrelin secretion (P = 0.03). Fasting ghrelin independently predicted GH burst frequency (r = 0.44, P = 0.005). The nutritional markers body mass index and body fat predicted postglucose and valley ghrelin but not fasting levels. Ghrelin parameters were inversely associated with fasting insulin, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, and IGF-I. HOMA-IR was the most significant predictor of most ghrelin parameters. Valley ghrelin independently predicted cortisol burst frequency (52% of variability), and ghrelin parameters independently predicted total triiodothyronine and LH levels. Higher ghrelin concentrations in adolescents with AN are a consequence of increased secretory burst mass and amplitude. The most important predictor of ghrelin concentration is insulin resistance, and ghrelin in turn predicts GH and cortisol burst frequency.
Optimal nonlinear estimation for a class of discrete-time stochastic systems

Recursive estimation for nonlinear discrete-time stochastic systems with additive white Gaussian observation noise is investigated. It is proved that for certain classes of systems, described either by finite Volterra series expansions or by state-linear realizations under certain algebraic conditions, the optimal conditional mean estimator is recursive and of fixed finite dimension. An example is presented to illustrate the structure of the estimators.
Continuous Cultures of Natural Populations of Phytoplankton in Dilute, Treated Sewage EFFLUENT1

ABST33ACT Seawater diluted with secondcary-treated sewage effluent provides excellent enrichment for the maintenance of mixed natural populations of marine phytoplankton in continuous culture. Treated effluent, sampled over 1 year, was consistent in the ratios of plant nutrients and similar in its properties of plant growth stimulation and level of toxicity. The heterogeneous continuous culture system produced large quantities of plant carbon with the concomitant removal of nitrogen and phosphorus from sewage effluent. The plant species that grew in the continuous cultures were common to the typical coastal phytoplankton and the selection and elimination of sDecies was gradual considering the chemical complexity of the sewage effluent enrichment.
Solid pseudopapillary tumours of the pancreas: spectrum of imaging findings with histopathological correlation

Solid pseudopapillary tumour (SPT) is an uncommon cystic exocrine pancreatic neoplasm. The typical patient is a female in the third decade of life presenting with pain and/or palpable mass. Classic imaging characteristics include large size, mixed solid and cystic nature, encapsulation and haemorrhage. A pancreatic mass with these features in a young adult female should raise suspicion for an SPT. Although typically a non-aggressive neoplasm with surgery curative in most cases, SPT may exhibit more aggressive features such as local invasion, metastases or recurrence in up to 20% of cases.
Nature and Tectonic Significance of Fault Zone Weakening

Bob Holdsworth of the University of Durham has made something of a cottage industry in organizing symposia on various fault-related topics under the auspices of the Geological Society of London, and then seeing the papers submitted to these symposia published in the Society's Special Publication series. This contribution, edited by Holdsworth and three other workers in the field, presents 17 papers organized into four sections; in addition to an introductory paper by the editors.
Thomas of Monmouth: Detector of Ritual Murder

Thomas de Monmouth, moine du chapitre cathedral de Norwich, est le createur de l'accusation de meurtre rituel adressee aux Juifs. C'est ce que montre l'A. en analysant la "reconstitution du crime" que les Juifs de Norwich auraient perpetre le Samedi Saint de 1144 en "crucifiant" un garcon de douze ans, le jeune William. Dans sa "Vie et miracles de saint William de Norwich", Thomas de Monmouth, six ans apres la decouverte du corps du jeune William, "etablit" et le crime rituel des Juifs, et la saintete du jeune garcon, sur un ton polemique: la plupart des gens de Norwich, dont l'eveque et le sherif, ne prenaient pas alors au serieux l'accusation de crime rituel, et ne s'etaient pas apercus, avant Thomas, de la saintete du malheureux enfant.