cssi/SciSciGPT-SciSciNet huggingface dataset:
Quantitative magnetic resonance imaging of brain development in premature and mature newborns

Definition in the living premature infant of the anatomical and temporal characteristics of development of critical brain structures is crucial for insight into the time of greatest vulnerability of such brain structures. We used three-dimensional magnetic resonance imaging (3D MRI) and image-processing algorithms to quantitate total brain volume and total volumes of cerebral gray matter (GM), unmyelinated white matter (WM), myelinated WM, and cerebrospinal fluid (CSF) in 78 premature and mature newborns (postconceptional age, 29-41 weeks). Total brain tissue volume was shown to increase linearly at a rate of 22 ml/wk. Total GM showed a linear increase in relative intracranial volume of approximately 1.4% or 15 ml in absolute volume per week. The pronounced increase in total GM reflected primarily a fourfold increase in cortical GM. Unmyelinated WM was found to be the most prominent brain tissue class in the preterm infant younger than 36 weeks of postconceptional age. Although minimal myelinated WM was present in the preterm infant at 29 weeks, between 35 and 41 weeks an abrupt fivefold increase in absolute volume of myelinated WM was documented. Extracerebral and intraventricular CSF was readily quantitated by this technique and found to change minimally. The application of 3D MRI and tissue segmentation to the study of human infant brain from 29 to 41 weeks of postconceptional age has provided new insights into cerebral cortical development and myelination and has for the first time provided means of quantitative assessment in vivo of early human brain development.
Core of the Crisis: Deregulation, the Global Savings Glut, and Financial Innovation in the Subprime Debacle

The subprime crisis in mortgage lending and the resulting wave of foreclosures have been hitting cities and communities all over the United States. First, Dan Immergluck argues that there are three...
Tachykinins mediate the potentiation of antigen-induced bronchoconstriction by cold air in guinea pigs

The role of tachykinins in the potentiation of antigen-evoked bronchoconstriction induced by inhalation of cold air was studied in guinea pigs. Cold air was delivered through a tracheal cannula to anesthetized, artificially ventilated guinea pigs sensitized with ovalbumin and pretreated with atropine (1.4 μmol/kg). Inhalation of cold air increased total pulmonary resistance (R L ) in a time-dependent manner; inhalation of cold air for 10 or 15 minutes, but not for 5 minutes, produced a significant increase in R L . Aerosolized ovalbumin (5 breaths) increased R L in a dose-dependent manner (0.5% to 5%). Inhalation of cold air for 5 minutes significantly enhanced both the peak and the duration of the increase in R L induced by 0.5% ovalbumin. The tachykinin neurokinin 2-receptor antagonist, SR 48968 (0.3 μmol/kg intravenously) inhibited both the peak and the duration of the bronchoconstriction induced by 5-minute inhalation of cold air and ovalbumin (0.5%), whereas it did not affect the response to ovalbumin (0.5%) alone. These findings suggest that exposure to cold air potentiates the bronchoconstriction response to antigen and that this potentiation is mediated by tachykinin release from sensory nerves.
A method for improving the estimation of membrane frequencies

Abstract A method for obtaining approximations of the natural frequencies of membranes is developed. An approximate expression for the radius of the bounding curve is first written as a truncated Fourier series. The deflection, which is written as a superposition of the modes of the circular membrane, is forced to vanish (approximately) on the approximated boundary. This generates a system of linear homogeneous equations, the unknowns in which are the amplitudes of the modes of the circle. Equating the determinant of coefficients to zero yields an equation from which the approximate frequencies may be found. It is shown that the first-order approximation obtained through this procedure is identical to a method given by Rayleigh. Approximate frequencies of the first several modes of membranes in the shapes of a square, an ellipse, and the limacon of Pascal are then determined as demonstrations of the new second-order approximation. The approximations of the first three natural frequencies of the ellipse were found to be in error by less than 5% for eccentricities of 0·8 or less, and the approximations of the first four frequencies of the square were found to be in error by less than 3%.
US Trauma Center Preparation for a Terrorist Attack in the Community.

Since the 2001 terrorist attacks on the United States, federal and state funding, primarily from the National Bioterrorism Hospital Preparedness Program, has resulted in a surge of hospital activity to prepare for future natural or human-caused catastrophes. Trauma centers were integrally involved in the response to the 2001 attacks as first receivers of patients, communication hubs, and as convergence sites for families, the worried well, volunteers, and donors. After the Madrid train station terrorist attack, Congress identified the need to study trauma center preparedness as an essential part of the nation’s emergency management system. The NFTC received a one-year grant funded by the Centers for Disease Control and Prevention (CDC/NCIPC) to survey the capability and capacity of trauma centers to respond successfully to mass casualty incidents, particularly those brought about by acts of terrorism. This report summarizes responses to a US CDC/NCIPC-funded survey, R 49 CE000792-01, sent to all designated or verified Level I and II trauma centers in the US, to which 33% or 175 trauma centers replied. The results are categorized by preparedness scoring, vulnerability, threats, and funding. Planning communication, surge capacity, diversion, sustainability, special populations, and finance represent additional categories examined in the survey. Trauma centers are a major resource in disaster management. One-hundred and seventy-five centers candidly reported their resources and vulnerabilities. This inventory should be expanded to all trauma centers and recommendations for change as discussed.
Histoplasma yeast and mycelial transcriptomes reveal pathogenic-phase and lineage-specific gene expression profiles

The dimorphic fungus Histoplasma capsulatum causes respiratory and systemic disease in mammalian hosts by expression of factors that enable survival within phagocytic cells of the immune system. Histoplasma’s dimorphism is distinguished by growth either as avirulent mycelia or as pathogenic yeast. Geographically distinct strains of Histoplasma differ in their relative virulence in mammalian hosts and in production of and requirement for specific virulence factors. The close similarity in the genome sequences of these diverse strains suggests that phenotypic variations result from differences in gene expression rather than gene content. To provide insight into how the transcriptional program translates into morphological variation and the pathogenic lifestyle, we compared the transcriptional profile of the pathogenic yeast phase and the non-pathogenic mycelial phase of two clinical isolates of Histoplasma. To overcome inaccuracies in ab initio genome annotation of the Histoplasma genome, we used RNA-seq methodology to generate gene structure models based on experimental evidence. Quantitative analyses of the sequencing reads revealed 6% to 9% of genes are differentially regulated between the two phases. RNA-seq-based mRNA quantitation was strongly correlated with gene expression levels determined by quantitative RT-PCR. Comparison of the yeast-phase transcriptomes between strains showed 7.6% of all genes have lineage-specific expression differences including genes contributing, or potentially related, to pathogenesis. GFP-transcriptional fusions and their introduction into both strain backgrounds revealed that the difference in transcriptional activity of individual genes reflects both variations in the cis- and trans-acting factors between Histoplasma strains. Comparison of the yeast and mycelial transcriptomes highlights genes encoding virulence factors as well as those involved in protein glycosylation, alternative metabolism, lipid remodeling, and cell wall glycanases that may contribute to Histoplasma pathogenesis. These studies lay an essential foundation for understanding how gene expression variations contribute to the strain- and phase-specific virulence differences of Histoplasma.
Resistance exercise increases human skeletal muscle AS160/TBC1D4 phosphorylation in association with enhanced leg glucose uptake during postexercise recovery

Akt substrate of 160 kDa (AS160/TBC1D4) is associated with insulin and contraction-mediated glucose uptake. Human skeletal muscle AS160 phosphorylation is increased during aerobic exercise but not ...
Hotspots organize clathrin-mediated endocytosis by efficient recruitment and retention of nucleating resources.

The formation of clathrin-coated pits (CCPs) at the plasma membrane has been reported to sometimes occur repeatedly at predefined sites. However, defining such CCP ‘hotspots’ structurally and mechanistically has been difficult due to the dynamic and heterogeneous nature of CCPs. Here, we explore the molecular requirements for hotspots using a global assay of CCP dynamics. Our data confirmed that a subset of CCPs is nucleated at spatially distinct sites. The degree of clustering of nucleation events at these sites is dependent on the integrity of cortical actin, and the availability of certain resources, including the adaptor protein AP-2 and the phospholipid PI(4,5)P2. We observe that modulation in the expression level of FCHo1 and 2, which have been reported to initiate CCPs, affects only the number of nucleations. Modulation in the expression levels of other accessory proteins, such as SNX9, affects the spatial clustering of CCPs but not the number of nucleations. On the basis of these findings, we distinguish two classes of accessory proteins in clathrin-mediated endocytosis (CME): nucleation factors and nucleation organizers. Finally, we observe that clustering of transferrin receptors spatially randomizes pit nucleation and thus reduces the role of hotspots. On the basis of these data, we propose that hotspots are specialized cortical actin patches that organize CCP nucleations from within the cell by more efficient recruitment and/or retention of the resources required for CCP nucleation partially due to the action of nucleation organizers.
A test of three fitting criteria for multiresponse non-linear modeling

This work evaluates objective functions for multiresponse non-linear modeling using computer simulations. Tests are performed under a variety of signal-to-noise ratios and noise variance–covariance structures. The standard error of prediction for the model parameters, computed from 50 trials, is used for performance comparisons. The full rank and rank-deficient problems are considered. For the full rank problem one model was investigated, a first-order two-step consecutive reaction model, and two objective functions were considered, the total sum of squares and the determinant criterion. No distinction could be made between the two objective functions for this model. For the rank-deficient case two models were investigated, a first-order two-step consecutive reaction as in the full rank case, and a pH titration model described by the Henderson–Hasselbalch equation. Three objective functions were investigated for the rank-deficient case, the total sum of squares, a weighted total sum of squares and the determinant criterion. The total sum of squares was found to perform poorly under all conditions tested compared to the weighted total sum of squares and the determinant criterion. The determinant criterion was found to perform much better than the other two criteria when the data have a combination of a low signal-to-noise ratio and high variance–covariance noise structure.
CONSTRUCT VALIDATION OF THE PERSONAL AND SOCIOPOLITICAL DIMENSIONS OF ROTTER'S INTERNAL- EXTERNAL LOCUS OF CONTROL SCALE

Summary.-The construct validity of two dimensions of the Rotter Internal-External Locus of Control Scale was investigated. Subjects (102 females and 63 males) completed measures of state and trait depression, a political activity inventory, and the locus of control sale. While the sociopolitical cluster of items showed evidence of construct validity, the personal cluster was not construct-validated. The need was stressed for further investigation of the validity of dimensions of locus of control. The present paper investigated the construct validity of the personal and social dimensions of locus of control assessed by Rotter's (1966) Internal-External Locus of Control Scale (I-E), using two subscales proposed by Berndt (1977). Rotter presented the I-E in his monograph as unidimensional. In 1970, Mirels analyzed the factor structure of the I-E scale and found two factors, one a personal control factor and the other a sociopolitical control factor. Most factor analyses of the I-E since then (e.g., Abrahamson, Schluderman, & Schluderman, 1973; Dixon, McKee, & McRae, 1976) have found similar factors, although there has been a general lack of agreement as to item content. Rotter (1975) recently acknowledged that the scale may be mulcidimensional and suggested that both general and specific factors have evdved as a result of increased differentiation of beliefs over time and from population to population. Dixon, McKee, and McRae ( 1976) carried the argument a bit farther specifying that the sociopolitical dimension developed as a result of increased alienation among citizens from political institutions in the wake of political turmoil and Watergate. Viney (1974) also implied that the sociopolicical dimension may have resulted from the political climate of the early 1970's. Berndt (1977) proposed two subscales of the I-E scale based on a survey of the item content in similar factors in seven selected studies. The subscale for personal control consisted of nine items, and the sociopolitical subscale contained five items. Berndt reported adequate Kuder-Richardson reliabilities for both subscales, and the low correlation between the subscales, compared with high correlations with the full scale, indicated that the two subscales were measuring separate aspects of locus of control. Berndt suggested that the personal I-E subscale, with Kuder-Richardson re
Modeling of in situ ultrafine atmospheric particle formation in the eastern United States

[1] The creation of new atmospheric particles from in situ nucleation influences climate through cloud-aerosol interactions and may negatively impact human health. Although recent observations show that nucleation is widespread in the eastern United States, the corresponding pathways remain uncertain. Combining extensive field measurements in Pittsburgh, Pennsylvania, with an aerosol dynamics and chemistry model assuming ternary NH3-H2SO4-H2O nuclei formation, we show excellent model-measurement agreement and predictive capability. The ternary NH3-H2SO4-H2O nucleation model is successful in predicting the presence or lack of nucleation on 19 out of 19 days with complete data sets in July 2001 and on 25 out of 29 days in January 2002. Reductions of ammonia emissions are predicted to decrease the frequency of nucleation events during both summer and winter, with a more dramatic effect during the summer. The response to changes in emissions of sulfur dioxide during the summer is counterintuitive. Reductions of sulfur dioxide and the resulting sulfate by up to 40% actually increase the frequency of the summer nucleation events. Modeling predicts the opposite effect in winter, with reductions of sulfur dioxide leading to fewer nucleation events.
Negative Refraction and Electromagnetically Induced Chirality

Negative refraction with minimal absorption obtained using quantum interference effects similar to electromagnetically induced transparency. Coupling a magnetic dipole transition coherently with an electric dipole transition leads to electromagnetically induced chirality, providing negative refraction.
Alcohol dose effects on stress response to cued threat vary by threat intensity

Rationale Clarification of alcohol’s effect on stress response during threat is critical to understand motivation for alcohol use and related alcohol-use disorders. Evaluation of stress response dampening (SRD) effects of alcohol has been limited by nonsystematic use of varied experimental methods and measures.
Binding characteristics and immunolocalization of porcine seminal protein, PSP-I

PSP-I, a 13 kDa protein purified from boar seminal plasma, was found to have about 50% amino acid sequence homology with a family of zona pellucida-binding proteins known as spermadhesins. These proteins are produced by the accessory gland(s) of the male reproductive tract and coat the spermatozoa during ejaculation. In this study, we have investigated the possible biological functions of PSP-I using a solid-phase protein binding assay and its site of synthesis using both Western blot and immunocytochemical analyses. PSP-I was found to bind a number of proteins including endo-beta-galactosidase digested ZP3, soybean trypsin inhibitor, IgA, IgG and alpha-casein, indicating that it may have multiple functions. The protein or carbohydrate structures were not critical in the binding, since polyvinyl sulfate could effectively inhibit the binding of PSP-I to these proteins. Western blot analysis using specific antiserum to PSP-I showed that the protein was present in the seminal vesicle but not in the testes, epididymis or prostate. The protein was revealed by immunocytochemical analysis in the epithelium of seminal vesicles but not in the testes or the epididymis. It is concluded that PSP-I is synthesized by the epithelium of the seminal vesicles, secreted into the semen during ejaculation, and may be involved in various reproductive functions, such as preventing premature acrosome reaction and immunosuppression.
The effect of postnatal caffeine administration on brain myelination

Abstract Rat pups were administered caffeine in a dosage of 20 mg/kg, 40 mg/kg or 80 mg/kg daily from birth through 17 days of postnatal age. Pups from each group were sacrificed at 17, 23, 30 or 70 days of age, their brains were removed, and myelin was quantitatively prepared. We observed a dose-dependent lag in brain weight and in myelin concentration through 30 days, with full recovery (and possibly overshoot) of the brain myelin concentration at 70 days. There was a persistent lag in brain weight. No discernible impairment of myelination or weight gain resulted from treatment with 20 mg/kg caffeine. The literature on mildly undernourished rats indicates that undernourishment is not a significant contributing factor.
TH‐B‐330D‐01: Quality Assurance Procedures for Digital Radiography

The use of digital radiography is becoming the normal form of image capture replacing film. With film there are numerous Quality Assurance (QA) procedures that have been developed that cover the film processor, retake analysis, patient dose and overall system image quality. The QA procedures for digital systems are just now being developed. Since the digital detector technologies vary and with variations in image processing methods it may seem difficult to develop standardized QA procedures. Yet the endpoints of optimized image quality and minimized patient dose need to be obtained. Therefore the Physicist needs to use the knowledge of the detector characteristics and processing methods as tools to maintain QA on digital systems. These procedures need to be rigorous enough to provide QA, yet they must be flexible enough to work for different detectors, processing methods and system applications. This lecture will provide an overview of the testing procedures for digital radiographic systems and suggest procedures that can be used to provide QA in digital radiography. Educational Objectives 1. Review detectortesting procedures used to assess digital systems. 2. Review QA procedures used in radiography and relate these to digital technologies. 3. Suggest QA procedures that can be used to evaluate digital systems.
Specific tumor-induced suppression of lymphocyte activity in the antibody-dependent tumoricidal reaction.

Although lymphocytes from normal, unsensitized CD8F1 mice demonstrated an antibody-dependent cytotoxic reaction against syngeneic breast tumor cells in vitro, lymphocytes from mice carrying breast tumors exceeding 1 g in weight invariably failed to demonstrate cytotoxicity against cells from the lymphocyte donor's tumor in the antibody-dependent reaction. Further, the tumor-induced suppression of this antibody-dependent lymphocyte reactivity was found to be tumor-antigen-specific, in that lymphocytes from an animal bearing a large tumor nevertheless were capable of participating in an antibody-dependent cytotoxic reaction against syngeneic breast tumor cells that were antigenically distinct from those of the lymphocyte donor. The specificity of suppression of antibody-dependent lymphocyte reactivity observed here indicates that only a small sub-group of those lymphocytes with potential for antibody-dependent cytocidal reactions actually participates in the reaction against any one particular antigen. This suggests a previously unrecognized antigen specificity at the level of the effector cell in the antibody-dependent cytotoxic reaction.
Improved reflectometry facility at the National Institute of Standards and Technology

We have recently completed construction of a high throughput, modest resolution soft x-ray monochromator installed at the Synchrotron Ultraviolet Radiation Facility of the National Institute of Standards and Technology. Although this monochromator will be used primarily to characterize the optical properties of multilayer-coated x-ray optics, the versatility of the instrument will enable us to measure such properties as reflectivity, transmission, diffraction, and scatter of a variety of components. We present measurements of monochromator throughput and resolution.
Translational regulation of T4 messenger RNA metabolism.

Abstract Standard conditions of incubation for T4 infected cells were developed from control studies so that reproducible isotope labelling data for mRNA synthesis could be obtained. Limited amounts of an essential amino acid caused a reduced rate of synthesis of both protein and mRNA. When puromycin or chloramphenicol was also present protein inhibition was greater but the rate of mRNA synthesis returned to normal. The data indicated that coordinated regulation of mRNA synthesis and translation had been present initially and that puromycin or chloramphenicol uncoupled mRNA synthesis from protein synthesis. A technique for regulating metabolism by limiting ATP generation was developed. Using this technique translational regulation of mRNA degradation was also demonstrated. It is proposed that translational regulation of mRNA lifetime is an intrinsic property of T4 mRNA metabolism.
Activation of Sp1 and its functional co-operation with serum amyloid A-activating sequence binding factor in synoviocyte cells trigger synergistic action of interleukin-1 and interleukin-6 in serum amyloid A gene expression.

The serum amyloid A (SAA) protein has been implicated in the progression and pathogenesis of rheumatoid arthritis through induction of collagenase activity in synovial fibroblast cells that line the joint tissues. We demonstrate that SAA is synergistically induced in synovial cells by interleukin (IL)-1 and IL-6 that are present at significantly high level in the synovial fluid of arthritis patients. These cytokines induced phenotypic changes in synovial cells, promoting protrusion and increased cellular contact. Induction of SAA under this condition is mediated by promoter elements located between −254 and −226, which contains binding sites for transcription factors Sp1 and SAA activating sequence binding factor (SAF). Mutation of these sequences abolishes SAA promoter response to IL-1 and IL-6. The role of Sp1 in SAA induction was demonstrated by increased DNA binding activity, phosphorylation, and increased protein content of Sp1 during cytokine treatment. Sp1 interacts with the SAA promoter in association with SAF as an SAF·Sp1 heteromeric complex. Furthermore, using a phosphatase inhibitor, we demonstrated increased transactivation potential of both Sp1 and SAF as a consequence of a phosphorylation event. These results provide first evidence for cytokine-mediated activation of Sp1 in synovial fibroblast cells and its participation in regulating SAA expression by acting in conjunction with SAF.
Method of Moments Using Monte Carlo Simulation

Abstract We present a computational approach to the method of moments using Monte Carlo simulation. Simple algebraic identities are used so that all computations can be performed directly using simulation draws and computation of the derivative of the log-likelihood. We present a simple implementation using the Newton-Raphson algorithm with the understanding that other optimization methods may be used in more complicated problems. The method can be applied to families of distributions with unknown normalizing constants and can be extended to least squares fitting in the case that the number of moments observed exceeds the number of parameters in the model. The method can be further generalized to allow “moments” that are any function of data and parameters, including as a special case maximum likelihood for models with unknown normalizing constants or missing data. In addition to being used for estimation, our method may be useful for setting the parameters of a Bayes prior distribution by specifying mome...
Studies of the resolution of racemic 1,1′-bi-2-naphthol with a dipeptide chiral selector identified from a small library

Several new stationary phases were prepared to study the structure-activity relationship of the chiral resolution of racemic 1,1'-bi-2-naphthol with a modified dipeptide Asn-Asn selector. The number of amino acid, the side chain protecting groups of the amino acid, and the Fmoc end-capping group all proved important for enantioselectivity. The linker also influenced enantioselectivity. Influence of the length of the linker appears to be related to the accessibility of chiral selectors. The bond through which the selector is attached to the linker proved important. Based on these results, it is postulated that hydrogen bonding interactions between one side chain amide group of one Asn and the oxygen on the backbone of another Asn with the two hydroxyl groups of the analyte play an important role in the resolution of racemic 1,1'-bi-2-naphthol with the modified dipeptide Asn-Asn selector.
The organization of torque and EMG activity during bilateral handle pulls by standing humans.

This study examined whether the torques and EMG activity that precede and accompany bilateral arm pulls made by standing humans demonstrate a pulse height form of organization. Nine adults made abrupt bilateral pulls in the sagittal plane against a handle, to force targets equal to 5, 10, 20, 40, 60, 80 and 95% of their maximal pulling force (%MPF). The force applied at the handle, ground reaction forces, the center of pressure (CP), and EMG activity in gastrocnemius (GS), biceps femoris (BF), tibialis anterior (TA) and quadriceps (QD) muscles were recorded. Our analysis divided the action into a pre-pull phase (events prior to the increase of handle force) and a pulling phase (while handle force was greater than zero). We evaluated the effects of %MPF on the durations and peak amplitudes of the pre-pull and pulling angular impulses about the ankle joint and on pre-pull EMG patterns. The results showed that the angular impulse associated with the pulling torque (due to the reactive force on the body during the pull) had a pulse height organization: peak torque increased linearly with %MPF, and the durations of the pulling torque were relatively constant. In contrast, a pulse height organization did not characterize the pre-pull period for either the angular impulse associated with ankle torque (due to net ground reaction force) or EMG activity in the leg muscles. Rather, peak ankle torque typically increased up to some submaximal %MPF and then plateaued, perhaps due to a constraining effect of foot length on CP. The durations of pre-pull ankle torques increased over the whole range of %MPF, thereby compensating for the limit on ankle torque. Depending on the subject, the muscles were recruited in two different orders: GS-BF-TA-QD, or GS-TA-BF-QD. As the %MPF increased, the EMG onset times of all four muscles occurred earlier, and there was a greater likelihood that the BF, TA and QD muscles would be recruited on a given trial. The changes in the ankle torque and EMG patterns were gradual, suggesting that the pre-pull phase could have one underlying form of organization, with parameters that are tuned to task goals and anatomical constraints.
Odor Intensity of Mixed and Unmixed Stimuli under Environmentally Realistic Conditions

Subjects judged the odor intensity of single odorants and binary mixtures of fixed or varying proportions presented in the atmosphere of an environmental chamber. The subjects were exposed to the vapors either continuously (15 min) or periodically (once a minute for 15 min). As found previously, the mixtures smelled less intense than predicted from the simple sum of their unmixed components. The degree of hypoadditivity proved about the same for the four pairs of odorants studied, but varied from periodic to continuous exposure. Periodic exposure led to a greater departure from simple additivity and confirmed the presence of the phenomenon of compromise whereby the mixture can smell less intense than its stronger component alone. Continous exposure led to a closer approximation to simple additivity and exhibited no compromise. Nevertheless, the behavior seen under continuous exposure apparently derived from a tendency for mixtures to exhibit less adaptation than their components. Whereas mixtures may seem...
Effect of magnesium chloride and potassium chloride on the sedimentation characteristics of ribonucleoprotein isolated from dog pancreas.

Ribonucleoprotein particles were isolated from dog pancreas under conditions of invariant ionic composition and analyzed by zone sedimentation in sucrose gradients. On the basis of calculated sedimentation coefficients, the particle population was considered as three fractions: monomeric ribosomes and subunits, S20,w 0 to 100; polysomes, S20,w 100 to 500; and large ribosomal aggregates, S20,w greater than 500. The distribution of the particle population was studied under conditions of variable magnesium ion concentration in one series and of variable potassium chloride concentration in another. Monomeric ribosomes dissociated into 57 s and 38 s subunits at concentrations of magnesium ion below 3 m M , The 57 s particle became the predominant species at 0·5m M -Mg2+ . The polysomal pattern, however, remained relatively stable in this range. The release of subunits from polysomes occurred at magnesium ion concentrations below 1 m M and was responsible for a decreased yield of this fraction. The yield of large aggregates increased markedly above 3 m M -Mg2+. The data indicate that ribosomes possess a heterogeneous range of magnesium ion dissociation constants. Magnesium ion concentration was demonstrated to play a dual part in this population of particles; (1) dissociation of monomers at low concentrations; (2) association of the particles into very large aggregates at high concentrations. The yield of the large aggregates was also increased at low concentrations of potassium chloride. Sedimentation analysis of the post-mitochondrial supernatant fraction in the absence of deoxycholate showed 60% as many monomeric ribosomes as in its presence, but the yield of polysomes was greatly reduced. The results suggest that most of the polysomes are bound to the endoplasmic reticulum in the cells of this tissue. Variations in magnesium ion concentration altered the sedimentation pattern of the post-mitochondrial supernatant fraction similarly to that of the isolated particles. The data support the conclusion that polysomes are not random aggregates, since the amount of the latter can be varied independently of that of polysomes by alterations in the ionic composition of the medium.
Opposing assembly mechanisms in a Neotropical dry forest: implications for phylogenetic and functional community ecology

Species diversity is promoted and maintained by ecological and evolutionary processes operating on species attributes through space and time. The degree to which variability in species function regulates distribution and promotes coexistence of species has been debated. Previous work has attempted to quantify the relative importance of species function by using phylogenetic relatedness as a proxy for functional similarity. The key assumption of this approach is that function is phylogenetically conserved. If this assumption is supported, then the phylogenetic dispersion in a community should mirror the functional dispersion. Here we quantify functional trait dispersion along several key axes of tree life-history variation and on multiple spatial scales in a Neotropical dry-forest community. We next compare these results to previously reported patterns of phylogenetic dispersion in this same forest. We find that, at small spatial scales, coexisting species are typically more functionally clustered than expected, but traits related to adult and regeneration niches are overdispersed. This outcome was repeated when the analyses were stratified by size class. Some of the trait dispersion results stand in contrast to the previously reported phylogenetic dispersion results. In order to address this inconsistency we examined the strength of phylogenetic signal in traits at different depths in the phylogeny. We argue that: (1) while phylogenetic relatedness may be a good general multivariate proxy for ecological similarity, it may have a reduced capacity to depict the functional mechanisms behind species coexistence when coexisting species simultaneously converge and diverge in function; and (2) the previously used metric of phylogenetic signal provided erroneous inferences about trait dispersion when married with patterns of phylogenetic dispersion.
A novel dual staining method for identification of apoptotic cells reveals a modest apoptotic response in infarcted mouse myocardium

Confocal scanning laser microscopy was used to investigate the myocardium of control C57BL/6 and plasminogen activator inhibitor 1 knockout (PAI-1KO) mice 3 days following persistent ligation of the left descending coronary artery. Paraffin sections taken from infarcted areas of the left ventricle were stained with antibodies recognizing cardiomyocytes, neutrophils, macrophages and apoptotic cells. In both animal groups, a strong neutrophil response was noted in the infarcted myocardium, with a large proportion of these cells also displaying staining for anti-alpha-sarcomeric actin in the PAI-1KO animals. Abundant macrophages were also identified in the infarcted regions of both animal groups, forming demonstrable streams at the border region in the C57BL/6 control animals. Surprisingly, only sparse cells from both animal groups were labeled with the apoptotic markers anti-cleaved caspase 3 antibody and anti-single stranded DNA antibody (following formamide treatment). A dual immunostaining protocol was developed to localize both of these apoptotic markers in the same cell. Again, only scattered cells were found displaying both markers in the zones of infarction, suggesting that 3 days of persistent ischemia results in a robust necrotic response, but only a very minor apoptotic response in this mouse model.
The Selection of Optimum Time Constants for RC Filters with Random Signals

The application of statistics to the measurement of random signals, with particular emphasis on count-rate-meters, is considered. It is shown that under certain criteria, there are optimum values of time constants in the countrate-meter circuit that will produce the desired results. While the emphasis is placed on the count-rate-meter, the same approach can be used to measure signals in the presence of noise where RC type smoothing is present.
Quantum states of string-inspired lineal gravity.

We construct quantum states for a (1+1)-dimensional gravity-matter model that is also a gauge theory based on the centrally extended Poincar\'e group. Explicit formulas are found, which exhibit interesting structures. For example, wave functionals are gauge invariant except for a gauge noninvariant phase factor that is the Kirillov-Kostant one-form on the (co)adjoint orbit of the group. However, no evidence for gravity-matter forces is found.
PDAs as cognitive aids for people with multiple sclerosis.

OBJECTIVE. Cognitive impairment is a common symptom for people with multiple sclerosis (MS). This study evaluated the effects of an occupational therapy training protocol using personal digital assistants (PDAs) as assistive technology for people with cognitive impairment related to MS. METHODS. Twenty participants were trained to use PDAs by an occupational therapist. Assessments of functional performance were taken at the start of an 8-week pretreatment period, at the beginning and end of training, and 8 weeks after the conclusion of training. RESULTS. Participants demonstrated the ability to learn how to use basic PDA functions and retain learning for at least 8 weeks. Functional performance increased significantly with PDA use, and this gain was maintained at 8-week follow-up. CONCLUSION. This study provides evidence of an association between an intervention providing training in the use of a PDA and improvements in the everyday function of people with cognitive impairment related to MS.
A ‘funnel’ turnpike theorem for optimal growth problems with discounting

Abstract A turnpike theorem for the optimal control problem with discounting is given. The optimal trajectory is shown to lie in an exponentially bounded region of the optimal steady-state. This region, referred to as a funnel, is determined by the discount rate of the problem. The funnel theorem reduces to the classical turnpike theorem when the discount rate is zero.
Combinatorics of torus diffeomorphisms

We construct dynamical partitions of the torus for a diffeomorphism that is isotopic to the identity. The existence and the combinatorics of the partitions is solely determined by the rotation set of the diffeomorphism. When the rotation set consists of a single non-resonant vector, there is a whole hierarchy of partitions analogous to the partitions of the circle into the closest return intervals under an irrational circle rotation. In particular, all such torus maps are infinitely renormalizable in a natural sense.
Examining the discourse on the limit concept in a beginning-level calculus classroom

Existing research on limits documents many difficulties students encounter when learning about the concept. There is also some research on teaching of limits but it is not yet as extensive as the research on student learning about limits. This study explores the discourse on limits in a beginning-level undergraduate calculus classroom by focusing on one instructor’s and his students’ discourses through a communicational approach to cognition. The findings indicate that some of the limit-related contexts in which students struggled coincided with those in which the instructor shifted his elements of discourse on limits. The instructor did not attend to the shifts in his discourse, making them implicit for the students. The study highlights that the discrepancies among participants’ discourses signal communicational breakages and suggests that future studies should examine whether teachers’ explicit attention to the elements of their discourse can enhance communication in the classrooms.
Heat flow at Grass Valley, California

Geothermal gradients, corrected for the effect of topographic irregularities, are calculated from the measurements of underground temperatures in the mines at Grass Valley, California. The gradient is 9.46 ± 0.16 °C/km for indefinitely persisting topography and 8.56 ± 0.16 °C/km if the topography has evolved in the last 106 years. The mean thermal conductivity of 14 specimens of granodiorite from Grass Valley is 7.68 ± 0.09 X 10−3 cal/cm sec °C; that of 15 specimens of porphyrite is 7.14 ± 0.14 X 10−3 cal/cm sec °C. Using the conductivity of the granodiorite, the heat flow is found to be 0.73 ± 0.01 X 10−6 cal/cm2sec and 0.66 ± 0.01 X 10−6 cal/cm2sec for the two physiographic histories assumed. No explanation of this low value can be deduced from this isolated determination. A simplified form of correction for the effect of topographic irregularities on underground temperatures is presented.
Some aspects of femoral morphology in Homo erectus

The available femora of lower and middle Pleistocene hominines were examined osteometrically and radiographically. This fossil sample was compared with samples of Romano-British and Bushmen femora. The results showed distinctive internal and external morphological patterns in the Homo erectus group. This pattern consisted, in part, of very thick cortical bone, narrow AP shaft diameters and a low point of minimum shaft breadth. Where preserved, the trabeculae of the medial femoral neck showed a distinctive diffuse pattern. The Trinil femora showed a basically sapient pattern although they demonstrated thickened cortical bone in the distal shaft. The restricted distribution of this thickened cortex suggests that it may not be homologous with the generally thickened cortex seen in Homo erectus . Several hypotheses are proposed to explain the thickened cortex in Homo erectus .
Synthesis of compounds related to antihemorrhagic vitamin K: I. Naphthalene as a starting material for the preparation of 2-methyl-1,4-naphthoquinone

2-Methyl-1,4-naphthoquinone, recently shown to possess very strong anti-hemorrhagic vitamin K activity, was prepared in a practical manner from naphthalene through the application of a series of well-known organic chemical reactions.
Models of nonlinear vibration. I. Oscillator with bilinear resistance.

(1989). Models of Nonlinear Vibration. I. Oscillator with Bilinear Resistance. Acta Oto-Laryngologica: Vol. 108, No. sup467, pp. 241-248.
Times of Turbulence

In July 1995, the American Society for Public Administration's Endowment Board established the Donald C. Stone Fund to honor the memory of this public administration legend. Income from this fund is used to sponsor a lecture or symposium at ASPA's national conference, which reflects Stone's varied interests and contributions to the field. This year marked the eighth Donald C. Stone Lecture. On March 18, Astrid E. Merget was ASPA's Stone Lecturer and gave the following speech.
Chemistry in Microfluidic Channels

General chemistry introduces principles such as acid−base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of solution-pairs are explored: (i) a visualization of laminar flow at the interface between two dye-colored fluid streams; (ii) an acid−base reaction at the fluid−fluid interface; and (iii) a precipitation reaction of calcium carbonate (calcite) crystals at the fluid−fluid interface. These laboratory exercises provide a simple and effective means to expose students to the unique physical behaviors that result under confined flow.
Immunoglobulins reactive with myelin basic protein promote CNS remyelination

We tested the hypothesis that immunoglobulins directed against a CNS autoantigen, myelin basic protein, may promote remyelination in the course of a chronic, immune-mediated demyelinating disease. SJL/J mice infected chronically with Daniel's strain of Theiler's virus served as an experimental model of MS. The spinal cords of these mice exhibit extensive primary demyelination and inflammation with minimal spontaneous remyelination. Treatment with whole antiserum or affinity-purified mouse immunoglobulins directed against rat or rabbit myelin basic protein increased new myelin synthesis as measured by quantitative morphometry. Electron microscopy revealed numerous oligodendrocytes in remyelinated CNS lesions and a relative lack of inflammatory cells. Viral antigen persisted in the spinal cord despite enhanced CNS-type remyelination. These findings indicate that immunoglobulins reactive with myelin autoantigens have the potential to promote myelin repair.
Spectrum and Distance of Source Sco XR-1

In a broad sky survey for x-ray sources in the 44-to 60-A range only Sco XR-1 was detected. The spectral evidence indicates that Sco XR-1 may lie within a few hundred light-years of the sun. Its spectrum appears to be complex possibly a mixture of thermal sources at different temperatures or of thermal and nonthermal components, as has been predicted for an active neutron star with an associated corona or magnetosphere.
Deuteron tensor moments for intermediate energy neutron-deuteron scattering

Abstract We present calculations of the tensor moments of deuteron polarization in neutron-deuteron scattering between 77 and 300 MeV lab kinetic energy in the hope that they will motivate measurements in this currently neglected area. The moments are found to be large compared with their maximum possible values, in contrast with the experience at lower energies. The reaction model on which the calculations are based is a form of single scattering. We evaluate the single scattering integral numerically and utilize a novel method for obtaining the necessary off-shell two-nucleon amplitudes based on relativistic considerations. We compare our results with the results obtained using a more complete model wmploying nucleon exchange and a phenomenological s-wave representing higher-order multiple scattering. In this way we demonstrate that our results are relatively independent of the less known contributions to the scattering amplitude, if we restrict our attention to the forward hemisphere. We also discuss sensitivity of these results to the D-state percentage of the deuteron.
Acidosis as a presenting feature of chloramphenicol toxicity

Metabolic acidosis has previously been described in the gray baby syndrome, but has not been documented as a presenting feature. Four seriously ill children (bronchiolitis, hypoaldosteronism, dysautonomia, Reye syndrome), ages 4 months to 11 years, received chloramphenicol (CAP) intravenously. After initial stabilization, unexplained metabolic acidosis occurred 40 to 81 hours after beginning CAP. Serum CAP concentrations were 84, 62, 80, and 30 μg/ml, respectively, when acidosis was recognized. Hypotension, hypothermia, and abdominal distension occurred a mean of 23 hours after the onset of acidosis. Acidosis resolved and signs of the gray baby syndrome cleared with the decrease in serum CAP concentrations. Metabolic acidosis should be considered an early sign of CAP toxicity, and CAP should be used in reduced doses in severely III patients, especially those with liver dysfunction.