cssi/SciSciGPT-SciSciNet huggingface dataset:
Regional characteristics of land use in Northeast and Southern Blue Ridge Province: Associations with acid rain effects on surface-water chemistry

The Direct/Delayed Response Project (DDRP) is one of several studies being conducted by the United States Environmental Protection Agency to assess risk to surface waters from acidic deposition in the eastern United States. In one phase of DDRP, land use, wetland, and forest cover data were collected for statistical samples of 145 Northeast lake and 35 Southern Blue Ridge Province stream watersheds in the United States. Land-use and other data then were extrapolated from individual to target watershed populations. Project statistical design allows summarization of results for various subsets of the target population. This article discusses results and implications of the land-use and land-cover characterization for both regions. Forest cover was the primary land use in both regions. In the Northeast, developed (agriculture and urban) land was positively associated with surface-water chemistry values for acid neutralizing capacity, Ca plus Mg, pH, and sulfate in the Pocono/Catskill subregion. Extensive wetlands and beaver activity occur in parts of the Northeast region, whereas topography limits wetland and riparian development in the Southern Blue Ridge Province. Northeast soils have low sulfate adsorption capacity, most watersheds are near sulfur steady state, and lake sulfate concentrations are controlled principally by levels of sulfur deposition. Net annual sulfur retention in Northeast watersheds is positively correlated with occurrence of wetlands and beaver impoundments. In contrast, most Southern Blue Ridge Province soils have high sulfate adsorption capacities, resulting in high net watershed sulfur retention. At the present time, stream sulfate concentrations and percent sulfur retention are controlled principally by soil chemical properties related to adsorption rather than atmospheric deposition and land use.
Crystallization of Pseudomonas aeruginosa AHL synthase Lasi using β-turn crystal engineering

In Gram-negative bacteria, intercellular communication and virulence regulation is mediated by the diffusible chemical signal acyl-homoserine-L-lactone (AHL). The AHL synthase enzymes produce a variety of AHLs from the substrates S-adenosyl-L-methionine and acyl-acyl carrier protein. LasI, the AHL synthase from Pseudomonas aeruginosa, has low solubility and has failed to crystallize despite extensive crystallization trials. Based on the previously determined structure of the AHL synthase EsaI, active soluble LasI was produced by re-engineering residues in a tight turn to produce a type I' beta-turn. The resulting protein is active, more stable than the wild-type LasI and has been crystallized in the cubic space group F23, with unit-cell parameters a = b = c = 154.90 A.
The kin recognition system of carpenter ants (Camponotus spp.) - II. Larger colonies

Previous investigations of small colonies (<10 workers each) of Camponotus spp. indicated that queen-derived recognition cues, transferred to and learned by workers, are of major importance in between-colony discrimination (Carlin and Holldobler 1983, 1986). However, queens may have contributed disproportionately to a communal label or “gestalt” in small colonies. Here we report experiments on groups of approximately 190 sister workers of C. floridanus, adopted to alien conspecific queens. In 1200 neutral arena encounters, adoptees were introduced to their own unfamiliar sisters, reared in their colony of origin; unfamiliar non-sisters were introduced as controls. Following tests of worker behavior, the queens were dissected. Aggression was equally strong in encounters between unfamiliar kin and encounters between nonkin, if the adoptive queen had fully-developed ovaries, was completely inseminated, and produced abundant brood. However, workers were significantly less aggressive in encounters between kin if their queens had less active ovaries and were incompletely inseminated. Thus the presence of a fully functional queen continues to prevent recognition of unfamiliar kin in larger colonies, but worker cues can become more important when the queen is ineffective. In addition, adoptees of productive queens were significantly less aggressive toward pure-colony sisters than the latter were to them, suggesting the involvement of a foreignlabel rejection mechanism (Getz 1982).
Modeling the Crystallization Kinetic Rates of Lactose via Artificial Neural Network

A mixed-suspension, mixed-product removal (MSMPR) draft-tube-baffle crystallizer was used to estimate lactose crystallization kinetic rates under different processing conditions. The processing parameters investigated were the degree of supersaturation (S), agitation speed (rpm), the amount of seed (seed), and residence time (τ). Crystallization kinetic rates, including nucleation, growth, and aggregation rates, were calculated from the experimental crystal size distributions (CSD) via a moment transformation method. Two approaches were used to develop a correlation between the processing conditions and kinetic rates. The conventional power law approach estimated the model parameters of an assumed functional form via regression analysis. An artificial neural network (ANN) approach was also used. ANN does not require an assumed function, it develops a function by learning from the experimental processing conditions and kinetic pairs. The results showed that the ANN approach gave a much better prediction of...
A dangerous myxoma

A 38-year-old female presented with worsening migraines complicated by one episode of transient global aphasia. Brain magnetic resonance imaging was suggestive of previous cerebral infarction. Echocardiogram demonstrated a mass in the left atrium suggestive of myxoma, and the patient was referred to our clinic for surgery. Intraoperative transesophageal echocardiogram confirmed a 3.8×1.8-cm echogenic mass in the left atrium (Fig. 1, Panel 1), with prominent frond-like projections (Fig. 1, Panel 2), prolapsing into the left ventricle in diastole (Fig. 1, Panel 3). The mass was attached to the left atrial septum and was excised with its stalk and underlying atrial endocardium; pathologic evaluation confirmed villous/friable atrial myxoma with gelatinous consistency grossly (Fig. 2A). Histologically, there was sparse cellularity and abundant myxoid matrix and the cytoarchitecture showed prominent branching and fingerlike projections (H and E, ×12.5) (Fig. 2B and C).
Activity of the quorum‐sensing regulator TraR of Agrobacterium tumefaciens is inhibited by a truncated, dominant defective TraR‐like protein

Horizontal transfer of Agrobacterium tumefaciens tumour-inducing plasmids requires opines, which are released from plant tumours as nutrients for the bacteria. The opine octopine causes synthesis of the quorum-sensing TraR protein, which activates several tra promoters in the presence of a pheromone called Agrobacterium autoinducer (AAI). A gene, traS, was previously found on the same Ti plasmid in an operon that directs the uptake of mannopine, another opine. TraS strongly resembles TraR but lacks a DNA-binding module. TraS did not activate a TraR-dependent promoter and blocked TraR function, probably by forming inactive heteromultimers. Expression of traS was induced by mannopine, although this induction was strongly inhibited by the favoured catabolites succinate, glutamine and tryptone. Mannopine inhibited conjugation in a TraS-dependent fashion, and artificial overexpression of TraS also inhibited conjugation. Favoured catabolites restored tra gene expression in wild-type strains but not in strains that overexpress TraS. Downstream of traS is a gene encoding a truncated, defective chemoreceptor whose expression abolished chemotaxis.
Placenta and maternal effects of marginal zinc deficiency during gestation in rats

Abstract Effects of a marginally zinc deficient diet (6 μg Zn/g diet) were investigated in the pregnant rat. In comparison to the control group (50 μg Zn/g diet), serum zinc concentration was significantly lower (P m and relative V max of placental LAP were also unaffected. It appears that maternal zinc status and weight gain are reduced in a marginal zinc deficiency to support placental function and fetal growth.
Does digermane exhibit free rotation? A test of barrier theory

Hartree–Fock/6-311G(3df,2p) analysis of the digermane internal rotation barrier shows that at 300 K digermane is in large amplitude (∼40°) oscillation about the staggered equilibrium structure. Quantum superposition (hyperconjugation between the germanyl groups) is predicted to contribute less than half of the 0.8 kcal/mol barrier energy, but it is key to sufficiently rigidize the molecule to prevent free rotation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
The Effect of Eimeria tenella Infection and Testosterone Treatment on the Weight of the Bursa of Fabricius in Young Chickens

Abstract E. tenella infections of young male and female chicks caused a premature regression of the bursa of Fabricius. Seven or 11 days after infection, the mean uncorrected bursa weights of parasitized male and female chicks were significantly less than those of uninfected control chicks. The mean corrected bursa weights (per 100 gm. total body weight) were also significantly less in E. tenella-infected chicks than in uninfected controls, but, since the growth of infected chicks was significantly retarded, these differences were not as great as those between mean uncorrected bursa weights. Intraperitoneal injection of testosterone also caused significant reduction in the mean corrected and uncorrected bursa weights of male and female chicks when compared to oil-injected controls. Weight gain was reduced in the testosterone-injected chicks and, 12 days after injection, the “growth indices” of testosterone-treated male and female chicks were significantly less than those of oil-injected controls. After both E. tenella infection and testosterone injection of young male and female fowl, the mean uncorrected weights of their bursae were lower than those of either E. tenella-infected or testosterone-treated birds. The corrected mean bursa weights of infected, testosterone-injected chicks were similar to those of uninfected testosterone-injected controls and less than those of E. tenella-infected oil-injected chicks. In 2 of 3 trials, infected, testosterone-treated male birds had corrected mean bursa weights significantly less than those of infected, oil-injected males. The mean bursa weight of female chicks in all groups tended to be less than those of similarly treated males but in no cases were their corrected mean bursa weights significantly different.
Changing Behavior Through Cognitive Change

The literature of social process has made widespread use of analogies to static equilibria in mechanical systems, of frictional concepts like resistance to change, and of such reifications as pyramids. The idea of organizations as mechanisms is so pervasive as to have produced its own psychological myths, and ideologically so dominant as to cause aversion to "organic theories of society." The concept of the organization as a machine is plausible when certain unusual conditions obtain: the goal of the organization requires the performance over long periods of time of a number of repetitive operations capable of routinization; obedience to authority can be relied upon throughout the system; the top authorities in the system have continuous access to all information that is relevant to the organization's success; nearly all problems that the organization will encounter can be foreseen and hence incorporated in procedural manuals. Management can then conceive of itself as the designers and operators of the ma...
Induction of autoantibodies to syngeneic prostate-specific membrane antigen by xenogeneic vaccination

Prostate-specific membrane antigen (PSMA) is a prototypical differentiation antigen expressed on normal and neoplastic prostate epithelial cells, and on the neovasculature of many solid tumors. Monoclonal antibodies specific for PSMA are in development as therapeutic agents. Methodologies to actively immunize against PSMA may be limited by immunologic ignorance and/or tolerance that restrict the response to self-antigens. Our studies have previously shown that xenogeneic immunization with DNA vaccines encoding melanosomal differentiation antigens induces immunity in a mouse melanoma model. Here we apply this approach to PSMA to establish proof of principle in a mouse model. Immunization with xenogeneic human PSMA protein or DNA induced antibodies to both human and mouse PSMA in mice. Monoclonal antibodies specific for mouse PSMA were generated to analyze antibody isotypes and specificity for native and denatured PSMA at the clonal level. Most antibodies recognized denatured PSMA, but C57BL/6 mice immunized with xenogeneic PSMA DNA followed by a final boost with xenogeneic PSMA protein yielded autoantibodies that reacted with native folded mouse PSMA. Monoclonal antibodies were used to confirm the expression of PSMA protein in normal mouse kidney. These results establish the basis for clinical trials to test PSMA DNA vaccines in patients with solid tumors that either express PSMA directly or that depend on normal endothelial cells expressing PSMA for their continued growth.
High-TECh thymus

In this issue of Blood , Kelly and colleagues provide a possible solution to poor thymic function and prolonged immune deficiency following allogeneic BMT by demonstrating the additive benefit of combining KGF with androgen blockade to speed recovery of thymic function and reconstitution of
What Are the Modern Classics? The Baruch Poll of Great Philosophy in the Twentieth Century

The millennial frenzy that generated several highly publicized “Best of the Century” lists early in 1999 planted in my mind the idea of conducting a poll asking my fellow philosophers to name the best works of philosophy in the twentieth century. I approached the project with some trepidation. The polls that had bounced around in the media in early 1999 had something crazed about them. “Hiroshima Voted Top News Event Of The Twentieth Century,” for example: what could one possibly do with such information? Furthermore, even polls that might have some use—the book and movie and musical recording lists that might guide one’s choice of casual entertainment—had in some cases gotten silly results with silly methods. Thus, we have a “top 100 American movies” list without a single film by Buster Keaton, a “top 100 novels” list produced by Random House in which Random House books were listed first when the experts tied, and so forth. All “best of” polls are afflicted with nearly insuperable problems of method and commensurability. The possibility of producing something silly in designing a philosophy poll loomed large. Perhaps asking philosophers to name their favorite books would be like asking mathematicians to name their favorite integers. Nevertheless, there is nothing prima facie absurd in asking philosophers to discriminate between important books and unimportant books. Every teacher does this in designing a syllabus for a course. And even if there is no sense in claiming that a poll of great books tells us what the great books are, at least it will tell us what they are believed to be. This is something I thought it would be fun to know. The goal decided, the question was how to do it. The polls so far had appealed to panels of experts; I was determined not to go that route. There is of course the regress problem: you need an expert to pick the experts. But there is the more THE PHILOSOPHICAL FORUM Volume XXX, No. 4, December 1999
Role of Pseudomonas aeruginosa Peptidoglycan-Associated Outer Membrane Proteins in Vesicle Formation

Gram-negative bacteria produce outer membrane vesicles (OMVs) that package and deliver proteins, small molecules, and DNA to prokaryotic and eukaryotic cells. The molecular details of OMV biogenesis have not been fully elucidated, but peptidoglycan-associated outer membrane proteins that tether the outer membrane to the underlying peptidoglycan have been shown to be critical for OMV formation in multiple Enterobacteriaceae. In this study, we demonstrate that the peptidoglycan-associated outer membrane proteins OprF and OprI, but not OprL, impact production of OMVs by the opportunistic pathogen Pseudomonas aeruginosa. Interestingly, OprF does not appear to be important for tethering the outer membrane to peptidoglycan but instead impacts OMV formation through modulation of the levels of the Pseudomonas quinolone signal (PQS), a quorum signal previously shown by our laboratory to be critical for OMV formation. Thus, the mechanism by which OprF impacts OMV formation is distinct from that for other peptidoglycan-associated outer membrane proteins, including OprI.
CONTROLS ON PHOSPHORUS CONCENTRATION AND ACCUMULATION IN OCEANIC SEDIMENTS

Understanding phosphorus (P) sedimentation in the ocean is important both for quantifying outputs in the marine phosphorus cycle and for determining the controls on phosphogenesis (the authigenic formation of carbonate fluorapatite) and phosphorite deposition (large accumulations of P-rich sediments on continental margins). In this study I have compiled literature data on sedimentary P concentrations and sedimentation rates from continental margins, phosphogenic continental margins, and open ocean environments. I have also calculated P accumulation rates, the product of P concentration, sediment density, and sedimentation rate in these settings. Sedimentary P concentrations exhibit a similar range in a wide variety of oceanic environments and sedimentation rate conditions. For example, P concentrations in continental margin sediments range from 8 to 108 μmol P g−1, with sedimentation rates from 80 to 8,000 m my−1. In open ocean sediments, the P concentration range is similar (7–307 μmol P g−1), even though sedimentation rates are generally about 100 times lower (2–50 m my−1). The exception to this are phosphogenic environments, where P concentrations are exceptionally high (580–3,700 μmol P g−1) while sedimentation rates are relatively low (20–310 m my−1). Phosphorus accumulation rates appear to be controlled by sedimentation rate in ocean sediments. Although P concentrations generally exhibit similar ranges, the large difference in sedimentation rates between various environments results in P accumulation rates that are several orders of magnitude higher in continental margins (90–8,000 μmol P cm−2 kyr−1) compared to open ocean sediments (2–75 μmol P cm−2 kyr−1). In the case of phosphogenic environments, low sedimentation rates result in P accumulation rates (80–6,300 μmol P cm−2 kyr−1) that are surprisingly similar to those of non-phosphogenic continental margin sediments.
Temperature influences sociality and activity of freshwater fish

Temperature is a critical environmental factor in the ecology of fish, significantly influencing their physiology and behavior. Previous studies on the effect of temperature have focused on the metabolic and growth rates of individual fish and on the social behavior of fish shoals in placid water. In this paper, we investigate the effect of changing temperature on shoals of giant danios as they swim in a water tunnel at 22, 25, and 28 °C. Fish activity is quantified in terms of rheotaxis and tail-beat frequency measured automatically by tracking fish shape. Fish social behavior is quantified in terms of average nearest neighbor distance (ANND) and polarization. Results show that both social behavior and individual activity are significantly affected by change in temperature. In particular, fish maximize their activity and ANND at 28 °C, while their polarization is maximized at 22 °C. These findings suggest that temperature influences both the social behavior and the energy expenditure of fish, whereby lower temperatures lead to more cohesive shoals with reduced fish activity.
High-Achieving Disadvantaged Students: A study of low SES Hispanic language minority youth

High-achieving disadvantaged Hispanic students identify with Hispanics and also aspire to the middle class.
On the orientation of lipids in chloroplast and cell membranes.

The widespread recognition of the corpuscular nature of membrane ultrastructure demands re-evaluation of established concepts of their molecular organization. Many aspects of membrane physiology, composition, and metabolism provide support for the proposal that most membranes consist of two-dimensional polymers of lipoprotein subunits. Such a model allows the activity, specificity, and adaptability attributed to biological membranes. Evidence which supports this corpuscular model for membranes and some inadequacies of the bimolecular lipid leaflet model are pointed out. The lamellae of plant chloroplasts are membranes which clearly consist of subunits (quantasomes). Their four surfactant lipids and pigments comprise 50% of the lipoprotein subunits. In each of these surfactant lipids there is found a limited and specific group of fatty ester components. This phenomenon suggests that the hydrocarbon chain of the fatty esters may specifically complement certain hydrophobic amino acid sequences in the membrane protein. The protein, then, would determine the sites where the lipid will be most firmly bound. It is proposed that the lipids of membrane subunits are bound by hydrophobic association of the hydrocarbon chains regions within the interior of the protein. The resulting two-dimensional lipoprotein aggregate would possess the strongly anionic charged groups of the phospholipids on its surface. Metabolically-driven alterations in conformation of such a flexible lipoprotein ion exchange membrane allows a consistent interpretation of biological membrane transport phenomena.
BRAF Mutations are Also Associated with Neurocutaneous Melanocytosis and Large/Giant Congenital Melanocytic Nevi:

NRAS and BRAF mutations occur in congenital melanocytic nevi (CMN), but results are contradictory. Sixty-six prospectively collected CMN patients were analyzed for NRAS Q61 mutations using Sanger sequencing. Negative cases were evaluated for BRAF V600E mutation. NRAS Q61 mutations affected 51 patients (77.3%), and BRAF V600E was found in 5 (7.6%). NRAS Q61 mutation affected 29 (80.6%) of 36 giant, 16 (80.0%) of 20 large, and 5 (62.5%) of 8 medium-size CMN; BRAF mutation affected 1 (5%) of 20 large and 4 (11.4%) of 36 giant CMN. Compared to NRAS, BRAF-mutated nevi show scattered/extensive dermal and subcutaneous nodules (100% BRAF+ vs 34.8% NRAS+) (P=0.002). Neurocutaneous melanocytosis (NCM) affected 16 (24.2%) of 66 patients, with NRAS Q61 mutation in 12 (75.0%), and BRAF V600E in 2 (12.5%), P=0.009. Two patients were negative for both mutations (12.5%). In conclusion, although NRAS Q61 mutations predominate, BRAF V600E mutation also affects patients with large/giant CMN (L/GCMN), and with NCM, a novel finding. BRAF V600E is also associated with increased dermal/subcutaneous nodules. These findings open the possibility of BRAF-targeted therapy in some L/GCMN and NCM cases.
Single crystal EPR studies of photoexcited triplet states of aromatic carbonyl molecules and substituted benzenes; enhancement of the EPR signals by energy transfer

Abstract Single crystal EPR studies of acetophenone (AP), 4-chloroacetophenone (CAP), benznitrile (BN) and phenylacetylene (PA) are reported. Zero field parameters were determined for all four systems. Hyperfine splittings were observed for BN and PA. Preliminary discussions on the electronic structures of these molecules are given. The advantage of using 1,4-dibromobenzene host is discussed.
A Note on Theta Reliability and Metric Invariance

A basic problem in empirical research using internal consistency reliability coefficients such as Cronbach's alpha is that the coefficients are sensitive to scale changes in the data. This leads to problems in cross-study comparison where the same variables are perhaps being measured, but in different units, and in substantive theoretical generalization, which must always be qualified in terms of a specified metric. In this note we show that coefficient theta, recently put forth by David J. Armor, does not have this defect—a property which should commend its application in sociological research.
The improved gray scale and the coarse-fine PCM systems, two new digital TV bandwidth reduction techniques

Two new digital television bandwidth-reduction techniques are presented with experimental results. Each provides twice the efficiency of a conventional pulse code modulation (PCM) system with similar picture fidelity, and each is simple and feasible for present-day spacecraft Implementation. The Improved Gray Scale PCM system effectively eliminates, by an averaging process, the gray scale contouring effect encountered in low-bit digital TV systems. The Coarse-Fine PCM system is somewhat more complex, but provides a higher fidelity reproduction of the original picture. The basic principles of operation of these two new data-compression techniques are given along with comparative pictorial results.
Properties of Azotobacter phage A14 and its DNA

Abstract Azotobacter phage A14 consists of a large polyhedral head and a contractile tail. It contains 34% DNA and has a particle weight of 470 × 106 daltons. Details of the head and tail structure were revealed by negative staining. Staining and fixed angle shadowing indicated that the head has icosahedral symmetry. Selective nucleation showed that the internal rod of the tail has a bilayer structure that inserts into the head. Exposure of A14 virions to high ionic strength results in disruption of the head, release of the DNA, and fragmentation of the tail components. A14 DNA is linear and sediments as a single component in neutral and alkaline solutions. It has a molecular weight of 160–170 × 106 determined by equilibrium sedimentation in CsCl density gradients, by electron microscope length measurements, and from the sedimentation coefficient. A G + C content of 54% was calculated from the melting temperature, and one of 51% from the buoyant density in CsCl. Phage A14 is molecularly and serologically unrelated to the Azotobacter phages previously studied in this laboratory.
Scattering amplitudes in p-adic string theory☆

Abstract In this letter we describe some features of the p-adic string theory. We show that different equivalent forms of real string scattering amplitudes lead to inequivalent p-adic string theories. Thus there is no canonical p-adic generalization of string theory, but we are able to give a prescription for what p-adic generalizations are possible. The reason for this multiplicity of p-adic theories is that the linear combinations of multiplicative character which are used to build the integral representations of string scattering amplitudes behave quite differently in the p-adic and real number fields.
When engineered to produce latent TGF-β1, antigen specific T cells down regulate Th1 cell-mediated autoimmune and Th2 cell-mediated allergic inflammatory processes

Abstract To determine whether T cells which produce large amounts of latent TGF-β1 are capable of down-regulating autoimmune and allergic disease, myelin basic protein (MBP)-specific and ovalbumin (OVA)-specific BALB/c cloned Th1 cells were transduced with cDNA for murine TGF-β1 by coculture with fibroblasts producing a genetically engineered retrovirus. The transduced MBP-specific Th1 cells were found to lose the capacity to provoke EAE in BALB/c mice, and to gain instead the ability to protect against EAE in (SJL×BALB/c) F1 mice immunized with proteolipid protein (PLP). This protective effect was not obtained with OVA-specific TGF-β1 transduced Th1 cells. The transduced OVA-specific Th1 cells did protect against airway hyperreactivity induced by Th2-cell mediated responses to inhaled OVA. This effect was again antigen specific and it also could not be obtained with untransduced OVA-specific Th1 cells. In both cases these effects of antigen specific TGF-β1 transduced T cells were nullified by administration of neutralizing anti-TGF-β mAb. Thus, the antigen specificity of the cloned T cells allows the site-specific local delivery of therapeutic active TGF-β1 to both Th1 and Th2 cell-mediated inflammatory infiltrates.
Concanavalin A and the initiation of thymic lymphoblast DNA synthesis and proliferation by a calcium-dependent increase in cyclic GMP level†

Exposure of a thymic lymphocyte population (suspended in serum-free synthetic medium) to the phytomitogen concanavalin A (Con A) causes brief (within the first 8 to 12 minutes) rises in the cellular contents of cyclic AMP and cyclic GMP. However, the rise in the cyclic GMP level is calcium (extracellular)-dependent, but the cyclic AMP rise is not. These changes are followed during the next hour by the initiation of DNA synthesis by a large fraction of the lymphoblast subpopulation which, like the preceding cyclic GMP rise, is calcium-dependent. The stimulated lymphoblasts eventually progress into mitosis. Additional observations indicate that Con A operates by sensitizing lymphoblasts to calcium ions which, in turn, cause the initiation of DNA synthesis by a process mediated by cyclic GMP, but not cyclic AMP.
Thermochemistry of liquid alloys of transition metals II. (Copper + titanium) at 1372 K

Abstract The enthalpies of mixing of solid titanium with liquid copper have been measured at 1372 K by high-temperature reaction calorimetry. The enthalpies of mixing, referred to the pure liquid components, have been calculated using literature values for the enthalpy of fusion and for the heat capacities of solid and liquid titanium. In this way the limiting partial enthalpy of solution of undercooled liquid Ti in liquid Cu at 1372 K is found to be − 7.65 kJ mol−1. We have found a well-defined minimum in the enthalpy interaction parameter, ΔH mix 1+l x(1 - x) , near x(Ti) = 0.5, which indicates some tendency toward chemical short-range order. The results have been compared with estimates derived from phase-diagram information, and from Miedema's theory. The agreement with the phase-diagram estimates is very good. However, our results differ significantly from the Miedema predictions.
Far-Infrared SEDs of Embedded Protostars and Dusty Galaxies. I. Theory for Spherical Sources

We present analytic radiative transfer solutions for the spectra of unresolved, spherically symmetric, centrally heated, dusty sources. We find that the dust thermal spectrum possesses scaling relations that provide a natural classification for a broad range of sources, from low-mass protostars to dusty galaxies. In particular, we find that, given our assumptions, spectral energy distributions (SEDs) can be characterized by two distance-independent parameters, the luminosity-to-mass ratio, L/M, and the surface density, Σ, for a set of two functions, namely, the density profile and the opacity curve. The goal is to use SEDs as a diagnostic tool in inferring the large-scale physical conditions in protostellar and extragalactic sources, and ultimately, evolutionary parameters. Our approach obviates the need to use SED templates in the millimeter to far-infrared region of the spectrum; this practice, common in the extragalactic community, relies on observed correlations established at low redshift that may not necessarily extend to high redshift. Furthermore, we demarcate the limited region of parameter space in which density profiles can be inferred from the SED, which is of particular import in the protostellar community as competing theories of star formation are characterized by different density profiles. The functionality of our model is unique in that in provides for a self-consistent analytic solution that we have validated by comparison with a well-tested radiative transfer code (DUSTY) to find excellent agreement with numerical results over a parameter space that spans low-mass protostars to ultra-luminous infrared galaxies (ULIRGs).
Retinoid Specificity of Interphotoreceptor Retinoid-Binding Protein

Interphotoreceptor retinoid-binding protein (IRBP), the predominant protein in the interphotoreceptor matrix of retina, has been implicated in transfer of retinoids between retinal pigment epithelium and photoreceptor cells. In this work, the interactions of several retinoids with IRBP were studied in order to clarify whether the protein displays specificity toward particular forms of these ligands. The equilibrium dissociation constants of complexes of 11-cis- and all-trans-retinols and retinaldehydes with IRBP were measured. It was found that IRBP contains two binding sites for 11-cis-retinaldehyde and for all-trans-retinaldehyde and retinol. Binding affinities followed the order: 11-cis-retinaldehyde > all-trans-retinol > all-trans-retinaldehyde > 11-cis-retinol. The kinetic parameters of the dissociation of these retinoids from binding sites on IRBP were measured by monitoring the rate of transfer of the retinoids from IRBP to synthetic unilamellar vesicles. 11-cis-Retinaldehyde and all-trans-retinol were found to dissociate from the strong binding site of IRBP 3-4-fold slower than all-trans-retinaldehyde and 11-cis-retinol. The higher binding affinities and the slower rates of dissociation from IRBP displayed by 11-cis-retinaldehyde and by all-trans-retinol correspond to the physiological need to shuttle these particular retinoids between pigment epithelium and photoreceptor cells across the interphotoreceptor matrix as part of the visual cycle.
Small-angle x-ray scattering from turnip yellow mosaic virus.

Abstract The small-angle X-ray scattering has been measured from solutions of turnip yellow mosaic virus and the associated protein. The data indicate that both particles are near spherical and about 140 A in radius. The virus is approximately uniform electron density. The protein is a water-filled spherical shell with a ratio of inner to outer radius of 0.75. The 140 A quoted represents the radius of the protein structure excluding external hydration. Thus both particles have large internal hydrations. A reasonable assignment of hydration to the protein and nucleic acid fractions of the virus particle is possible, which gives the particle an approximately uniform electron density.
Fluid Management of Diabetic Ketoacidosis

In last August9s issue (16:304, 1995), Roberts commented on recent recommendations for the fluid management of diabetic ketoacidosis (DKA). This issue has great importance because the older recommendations or "traditional" therapy begun in the 1960 to 1990 era was associated with occasional serious and sometimes fatal outcomes because of central nervous system (CNS) damage. One pedagogical problem results from calling the complication "cerebral edema"; a more accurate term is cerebral swelling because the excess water from therapy is largely in cells, not the interstitial fluids, as is true of edema. Imaging studies show the ventricles to be small, similar to the situation in lead poisoning or cerebral hypoxia. Understanding the mechanism for the swelling will make it easier for the therapist to monitor the administration of fluid. The initial swelling may occur before therapy for reasons we can only surmise or that are unknown. We do know that osmoprotective molecules (myoinositol, taurine, and perhaps others) will enter or be produced in cells in a hyperosmolar state such as DKA. This increase in cellular solute will attract water by osmosis. When fluid that has a lower sodium chloride concentration than interstital fluid (Na, 150 mEq/L; Cl, 118 m/Eq/L) is administered rapidly, either intravenously or orally, the tight junctions of the CNS vasculature admit water molecules by diffusion more rapidly than sodium and chloride ions; there is about a 4-hour lag time in equilibrium.
Does the Potential for Chaos Constrain the Embryonic Cell-Cycle Oscillator?

Although many of the core components of the embryonic cell-cycle network have been elucidated, the question of how embryos achieve robust, synchronous cellular divisions post-fertilization remains unexplored. What are the different schemes that could be implemented by the embryo to achieve synchronization? By extending a cell-cycle model previously developed for embryos of the frog Xenopus laevis to include the spatial dimensions of the embryo, we establish a novel role for the rapid, fertilization-initiated calcium wave that triggers cell-cycle oscillations. Specifically, in our simulations a fast calcium wave results in synchronized cell cycles, while a slow wave results in full-blown spatio-temporal chaos. We show that such chaos would ultimately lead to an unpredictable patchwork of cell divisions across the embryo. Given this potential for chaos, our results indicate a novel design principle whereby the fast calcium-wave trigger following embryo fertilization synchronizes cell divisions.
Autonomic ganglia, acetylcholine receptor antibodies, and autoimmune ganglionopathy.

Nicotinic acetylcholine receptors (AChR) are ligand-gated cation channels that are present throughout the nervous system. The ganglionic (α3-type) neuronal AChR mediates fast synaptic transmission in sympathetic, parasympathetic and enteric autonomic ganglia. Autonomic ganglia are an important site of neural integration and regulation of autonomic reflexes. Impaired cholinergic ganglionic synaptic transmission is one important cause of autonomic failure. Ganglionic AChR antibodies are found in many patients with autoimmune autonomic ganglionopathy (AAG). These antibodies recognize the α3 subunit of the ganglionic AChR, and thus do not bind non-specifically to other nicotinic AChR. Patients with high levels of ganglionic AChR antibodies typically present with rapid onset of severe autonomic failure, with orthostatic hypotension, gastrointestinal dysmotility, anhidrosis, bladder dysfunction and sicca symptoms. Impaired pupillary light reflex is often seen. Like myasthenia gravis, AAG is an antibody-mediated neurological disorder. Antibodies from patients with AAG inhibit ganglionic AChR currents and impair transmission in autonomic ganglia. An animal model of AAG in the rabbit recapitulates the important clinical features of the human disease and provides additional evidence that AAG is an antibody-mediated disorder caused by impairment of synaptic transmission in autonomic ganglia.
Ageing reduces nitric‐oxide‐ and prostaglandin‐mediated vasodilatation in exercising humans

In older humans, infusions of endothelial agonists suggest endothelial dysfunction, due in part to less nitric oxide (NO)- and prostaglandin (PG)-mediated vasodilatation, and a shift toward PG-mediated vasoconstriction. Ageing can also be associated with lower exercise blood flow (exercise hyperaemia), but the vascular mechanisms mediating this remain unknown. Notably, in young adults, inhibition of NO and PGs during exercise decreases exercise hyperaemia by ∼20 and ∼12%, respectively. We tested our first hypothesis that in older humans inhibition of NO would decrease hyperaemia, but that inhibition of PGs would increase hyperaemia by blocking vasoconstrictor PGs. Fifteen older subjects (65 ± 3 years) performed dynamic forearm exercise for 20 min (20 contractions min−1). Forearm blood flow (FBF) was measured beat-to-beat with Doppler ultrasound, while saline or drugs were infused sequentially via brachial artery catheter in the exercising forearm. After achieving steady-state exercise, l-NAME (25 mg) was infused over 5 min to inhibit NO synthase. After a further 2 min of exercise (saline), ketorolac (6 mg) was infused over 5 min to inhibit PGs, followed by a futher 3 min of exercise with saline. Drug order was reversed in seven subjects. l-NAME reduced steady-state exercise hyperaemia by 12 ± 3% in older subjects (P 0.4). The effects of l-NAME and ketorolac were independent of drug order. By comparing these results with our previous results in young adults, we tested our second hypothesis that in older humans inhibition of NO or PGs would have less impact on exercise hyperaemia due to less vasodilatation from these signals. Our results suggest that, compared with young adults, in older humans the relative contribution of NO to exercise hyperaemia is reduced ∼45% (22 ± 4 versus 12 ± 3%), but the role of PG in mediating vasodilatation is lost in ageing human skeletal muscle. Lower exercise hyperaemia in older humans may be mediated in part by less NO- and PG-mediated vasodilatation during exercise.
Reliability of identification of 655 sentinel lymph nodes in 263 consecutive patients with malignant melanoma.

Abstract Background The purpose of this study of sentinel lymph node biopsies (SLN) was threefold: to compare the reliability of lymphazurin blue dye to radioactive technetium 99m sulfur colloid (TC); to evaluate the reliability of frozen section examinations of sentinel lymph nodes; and to determine how much SLN dissections prolonged operative time. Study design We evaluated the records of 263 consecutive patients with intermediate and high-risk melanomas (1.0 mm or thicker, or Clark Level IV or greater), who were treated by a single surgeon at the Yale Melanoma Unit between October 1, 1997, and September 30, 2001, and followed for more than 18 months. Results A total of 655 SLN were identified and removed from these 263 consecutive patients. Radioactive colloid was found to be more reliable (100%) in identifying the SLN than lymphazurin blue dye (51%) in the nodes of the patients. Twenty-eight patients (11%) had positive sentinel lymph nodes, and 2 patients (7%) had false-negative frozen sections. Three patients (11%) had false-negative frozen sections; tumor was found subsequently on permanent sections only after special immunohistochemical stains were used. The location or removal of SLN did not prolong the operative procedure unreasonably, requiring an average of 7 to 20 minutes for removal of SLN, and 33 minutes for frozen section reports, during which time the primary tumor resection and wound coverage were performed. Conclusions SLN were found in all 263 patients. All SLN were identified reliably with radioactive colloid. Because blue dye was found in only half of the radioactive nodes, it is not appropriate to use this as the only marker for locating the SLN. This large series of patients attests to the reliability of frozen sections in identifying SLN harboring metastases, with 82% of the patients with nodal metastases identified in this fashion.
Exposure history of separated phases from the Kapoeta meteorite

— The cosmogenic radionuclides, 10Be, 26Al, 36Cl, and 53Mn were measured in selected clasts and matrix samples from the howardite Kapoeta. Previous measurements of cosmogenic 21Ne indicate higher cosmic-ray exposure ages for bulk samples than for some separated clasts or mineral separates. A possible interpretation for this difference in apparent exposure ages is a complex recent exposure history for Kapoeta. In this scenario some constituents are exposed to cosmic rays in a 2π geometry as part of a larger body immediately preceding its 4π exposure in a smaller body. To test this scenario we measured cosmogenic radionuclides in several clasts from Kapoeta. These measurements are consistent with a simple single-stage 4π exposure history during which the entire inventory of cosmogenic radionuclides was produced. Taken together, these data are most consistent with a single-stage 4π exposure lasting ∼3 Ma. This scenario is nevertheless consistent with models in which the exposure of some constituents of Kapoeta to energetic particles occurred at an earlier time, as is indicated by 21Ne measurements. However, from our data we conclude that insubstantial quantities of cosmogenic radionuclides were inherited from this earlier irradiation; this earlier exposure to energetic particles must have predated the recent exposure by at least ∼10 Ma to allow for the decay of the long half-life cosmogenic radionuclides.
How Well Do Compustat NOL Data Identify Firms with U.S. Tax Return Loss Carryovers

Although Compustat net operating loss (NOL) data are an underlying component of most proxies of corporate tax incentives, there is little empirical evidence regarding how Compustat NOLs relate to firms' tax‐loss positions per their U.S. tax returns. We use confidential U.S. tax return data for a sample of large corporations over the period 1981–1995 to compute firms' U.S. tax‐loss carryovers and construct a matched sample with Compustat data. We then evaluate how well Compustat NOL data works as an indicator of firms' U.S. tax‐loss positions, identify sources of misclassification errors, and investigate the effectiveness of using additional Compustat data screens. We find that screening for U.S. current income tax or total pretax income successfully reduces certain types of misclassification errors. We conclude that care should be used in constructing U.S. tax‐loss proxies, particularly when the research setting involves firms with foreign operations or corporate acquisitions activity.
Effect of orienting fields on agglomeration in dilute dispersions of magnetic fine particles

Static light scattering was used to investigate dilute dispersions of fine gamma -Fe/sub 2/O/sub 3/ magnetic particles. The particles were acicular and on average 0.39 mu m long and 0.056 mu m in diameter. They were dispersed in organic solvents at concentrations of approximately 10/sup -4/ vol%, corresponding to an average interparticle separation of 9 mu m. Computer programs using a coupled dipole algorithm to predict the scattering from the particles were written. Experimental results do not agree with computer calculations of the light scattering from single particles, but are consistent with scattering from thick ropelike agglomerates of particles. The size of these agglomerates was estimated after 10 s to be less than 100 particles, while the thickness of the ropes is at least 5 particles. >
Regulation of DNA Methylation in Rheumatoid Arthritis Synoviocytes

Rheumatoid arthritis (RA) is a chronic inflammatory disease in which fibroblast-like synoviocytes (FLS) exhibit an aggressive phenotype. Although the mechanisms responsible are not well defined, epigenetic determinants such as DNA methylation might contribute. DNA methyltransferases (DNMTs) are critical enzymes that establish and maintain DNA methylation. We evaluated whether proinflammatory cytokines might contribute to differential DNA methylation previously described in RA FLS through altered DNMT expression. FLS were obtained from RA and osteoarthritis (OA) synovium at the time of total joint replacement. Gene expression was determined by quantitative real-time PCR and protein expression by Western blot analysis. DNMT activity was measured with a functional assay, and global methylation was determined by an immunoassay that detects methylcytosine. Resting expression of DNMT1, -3a, and -3b mRNA were similar in RA and OA FLS. Western blot showed abundant DNMT1 and DNMT3a protein. Exposure to IL-1 decreased DNMT1 and DNMT3a mRNA expression in FLS. Dose responses demonstrated decreased DNMT expression at concentrations as low as 1 pg/ml of IL-1. DNMT mRNA levels decreased rapidly, with significant suppression after 2–8 h of IL-1 stimulation. IL-1 stimulation of OA FLS did not affect methylation of LINE1 sites but led to demethylation of a CHI3L1 locus that is hypomethylated in RA FLS. Chronic IL-1 stimulation also mimicked the effect of a DNMT inhibitor on FLS gene expression. Exposure to proinflammatory mediators reversibly alters DNA methylation in FLS by decreasing DNMT expression and function. These data suggest that IL-1 can potentially imprint cells in chronic inflammatory diseases.
Cellular pattern formation during retinal regeneration: A role for homotypic control of cell fate acquisition

A dominant mechanism of cellular patterning in the growing fish retina is control of cell fate acquisition by negative feedback signals arising from differentiated cells. We tested the ability of a computational model of this pattern formation mechanism to simulate cellular patterns in regenerated goldfish retina. The model successfully simulated quantitative features of in vivo regenerated patterns, indicating that regenerating retina has access to and utilizes patterning mechanisms that are operational during normal growth. The atypical patterns of regenerated retina could arise in part from regenerative progenitors that, compared to normal growth progenitors, are less responsive to the feedback patterning signals.