cssi/SciSciGPT-SciSciNet huggingface dataset:
Multicellular signalling model for DNA double-strand break repair kinetics after low-dose radiation

This paper introduces the Multicellular Signalling (MULTISIG1) model in which DNA double-strand break (DSB) repair initiation requires intercellular stress-response signalling from a threshold number of cells with DSBs, which occurs at the threshold radiation absorbed dose, T. The model applies to low radiation doses and employs an exponential distribution of times to DNA DSB repair completion with mean β. The MULTISIG1 model is found to be consistent with published data for γ-H2AX foci removal (reflecting DSB repair kinetics) after exposing cultures of confluent (non-dividing) human-derived lung fibroblast (MRC-5 line) to low-dose, 90-kV machine X-rays. T is estimated to be slightly greater than 1.2 mGy, a dose associated with, on average, about 1 electron track (form ionisations) per cell nucleus. β is estimated to be about 2.5 h and the corresponding rate of break repairs (μ) is estimated to be about 0.4 break repairs/h on different DNA molecules.
Computer system resource requirements of novice programming students

The characteristics of jobs that constitute the mix for lower division FORTRAN classes in a university are investigated. Samples of these programs are also benchmarked on a large central site computer and two minicomputer systems. The conclusion of this study is that a carefully chosen minicomputer system could offer service at least the equivalent of the service provided by the central site system, and that certain aspects of this service could be distinctly better.
Solder-joint reliability in electronics under shock and vibration using explicit finite-element sub-modeling

In this paper, the modeling approaches for first-level solder interconnects in shock and drop of electronics assemblies have been developed without any assumptions of geometric-symmetry or loading symmetry. The problem involves multiple scales from macro-scale transient-dynamics of electronic assembly to micro-structural damage history of interconnects. Previous modeling approaches include, solid-to-solid sub-modeling (Zhu et. al., 2001) using a half test PCB board, shell-to-solid sub-modeling technique using a quarter-symmetry model (Ren et. al., 2003; 2004). Inclusion of model symmetry in state-of-art models saves computational time, but targets primarily symmetric mode shapes. The modeling approach proposed in this paper enables prediction of both symmetric and anti-symmetric modes, which may dominate an actual drop-event. Approaches investigated include, smeared property models, Timoshenko-beam element models, explicit sub-models, and continuum-shell models. Transient dynamic behavior of the board assemblies in free and JEDEC-drop has been measured using high-speed strain and displacement measurements. Model predictions have been correlated with experimental data.
Tooth mutilation in the Caribbean: Evidence from a slave burial population in barbados

Dental mutilation on slave burials excavated from a sugar plantation cemetery on the Caribbean island of Barbados reflects on the question of African slaves and their New World born slave descendants perpetuating this widespread African practice in the New World. Physical anthropological and ethnohistorical evidence from Barbados and other areas leads to the tentative conclusion that dental mutilation (and body scarification) disappeared among New World Black slaves. Reasons relating to adaptive responses to the institution of slavery, and changes in esthetic values as a result of the creolization process, are offered to help account for this disappearance.
Localized, stereochemically sensitive hydrophobic packing in an early folding intermediate of dihydrofolate reductase from Escherichia coli.

Mutational analysis was performed to probe the development of hydrophobic clusters during the early events in the folding of dihydrofolate reductase. Replacements were made in several hydrophobic subdomains to examine the roles of hydrophobicity and stereochemistry in the formation of kinetic intermediates. Amide protons in two of these clusters, including residues I91, I94, and I155, have been shown to be protected against solvent exchange within 13 ms of folding. Additional hydrophobic clusters were probed by substitutions at residues I2, I61, and L112; these residues are not protected from exchange until later in the folding reaction. Valine and leucine replacements at positions I91, I94, and I155 significantly diminish the formation of the burst phase kinetic intermediate, relative to the wild-type protein. In contrast, I2 and I61 are insensitive to these substitutions in the first 5 ms of the folding reaction, as is the replacement of L112 with either isoleucine or valine. These results demonstrate that the tightly packed core of dihydrofolate reductase is acquired in a non-uniform fashion, beginning in the submillisecond time frame. The progressive development of specific side-chain packing in localized hydrophobic clusters may be a common theme for complex protein folding reactions.
Hematocrit levels and associated Medicare expenditures

Abstract Clinical studies and the National Kidney Foundation-Dialysis Outcomes Quality Initiative guidelines suggest that a target hematocrit of 33% to less than 36% is appropriate for patient benefit. Previous studies have shown an association of lower risks for death and hospitalization when hematocrits were 33% to less than 36%. In this study, we assessed the relationship between hematocrit value and associated Medicare expenditures, analyzing incident Medicare hemodialysis patients from January 1, 1991, through June 30, 1995. All patients survived at least 90 days to normalize eligibility and an additional 6-month entry period to assess comorbidity and hematocrit values. All patients were followed up from July 1, 1991, through December 31, 1996. We assessed the association between hematocrit values in the 6-month entry period and the Medicare-allowable Part A and Part B per-member-per-month (PMPM) expenditures in the follow-up period, controlling for other variables, including patient demographic characteristics, comorbid conditions, and severity of disease. We found that hematocrits of 33% to less than 36% and 36% and higher were associated with lower Medicare-allowable payments in the follow-up period. Compared with reference patients with hematocrits of 30% to less than 33%, the Medicare-allowable PMPM expenditures were significantly greater for patients with hematocrits less than 27% and 27% to less than 30% (12.7% and 5.3%, respectively), and the Medicare-allowable PMPMs were significantly less for patients with hematocrits of 33% to less than 36% and 36% and higher (6.0% and 8.2%, respectively). Although these findings suggest that the treatment of anemia may be associated with significant savings in total patient Medicare expenditures, caution should be considered because these findings are associations and should not be deemed as showing causality.
Adenosine triphosphate (ATP) treatment of hypoxic pulmonary hypertension (HPH): comparison of dose dependence in pulmonary and renal circulations.

Abstract In this study we investigated the relationship between pulmonary and renal responses to a low dose infusion of adenosine triphosphate-magnesium chloride (ATP-MgCl 2 ) in a newborn piglet model of hypoxic pulmonary hypertension (HPH). Three- to five-day-old piglets were cannulated for the measurement of pulmonary and systemic arterial pressure, pulmonary and renal artery flow, and urine output. The animals were then made hypoxic by ventilation with a mixture containing 10% oxygen, 4% CO 2 , and balance nitrogen. Serial infusions of ATP-MgCl 2 at 0.01, 0.025, 0.05, 0.1, 0.5, and 1.0 mg/kg/min were compared to preinfusion hypoxia baselines. Hypoxia alone produced a significant elevation in pulmonary artery pressure (73%) and a reduction in p O 2 . All dose rates of ATP-MgCl 2 ⩾ 0.05 mg/kg/min produced a significant decrease in mean pulmonary artery pressure. However, as baseline mean pulmonary artery pressure increased there was an increased sensitivity to ATP-induced vasodilation. Pulmonary artery flow did not change during ATP infusion, thus, the change in pulmonary vascular resistance accounted for the decrease in pulmonary artery pressure. In contrast to the response of the pulmonary vasculature, systemic pressure was significantly decreased only during the 1.0 mg/kg/min infusion. Renal blood flow decreased by 46% during hypoxia and decreased further only during the highest dose rate of ATP infused (i.e., 1.0 mg/kg/min). Creatinine clearance (Ccr) and fractional reabsorption of Na (FreNa) also fell during hypoxia, but were not further altered during all but the highest dose of ATP infused. These data suggest that a low dose infusion of ATP-MgCl 2 could decrease the vasoconstriction associated with HPH without concomitant adverse systemic or renal side effects.
The Ultrastructure of Bone Marrow Histiocytes in Megaloblastic Anaemia and the Anaemia of Infection

Summary. An electron-microscopic study was made of the iron in the histiocytes in niegaloblastic anaemia and in the anaemia of infection. The particulate iron seen by Prussian Blue staining in the histiocytes in megaloblastic anaemia was demonstrated by electron microscopy to be bound in the vesicles, while the diffuse iron staining in the anaemia of infection was related to the free dispersion of iron-containing particles in the cytoplasm of the histiocytes. The phagocytosis of erythroblasts at various stages of maturity occurred in cases of niegaloblastic anaemia and resulted in a picture showing every stage of degradation. Phagocytosis of erythroblasts by histiocytes was not seen in the marrows of patients with the anaemia of infection nor did it occur in niegaloblastic anaemia in remission.
Albumin-stimulated TGFβ-1 in renal tubular cells is associated with activation of MAP kinase

Proteinuric renal diseases are often associated with progressive tubulointerstitial fibrosis that usually defines the degree and rate of progression of renal failure. Glomerular filtration of excess albumin, the dominant protein in proteinuria, into proximal tubule could provide the stimulus to induce certain fibrogenic cytokines from proximal tubular cells (PTC), which may account for fibrosis in the interstitium. To explore this hypothesis we tested the effect of bovine albumin in PTC in culture on the expression and secretion of transforming growth factor (TGF) β-1, a prominent fibrogenic cytokine. TGFβ-1 expressed by cultured PTC was measured by enzyme-linked immunosorbent assay (ELISA) and indirectly by reverse-transcription polymerase chain reaction (RT-PCR). Relative messenger ribonucleic acid (mRNA) levels were measured in ethidium bromides stained gels, by comparison to transcripts for 18s ribosomal RNA. Activated mitogen-activated protein (MAP) kinase was estimated by Western blot with phosphotyrosine-specific antibody. Following incubation of PTC with albumin determination of TGF β-1 mRNA in PTC and TGF β-protein in culture medium both indicated a time- and dose-dependent increase. MAP kinase (p44/42) was activated within 5 min of exposure to albumin. Inhibition of the MAP kinase cascade by PD98059 attenuated the effect of albumin on TGF β-1 expression. These observations suggest that overexpression of TGF β-1 by PTC in response to albumin is regulated through a MAP kinase signaling pathway. This mechanism may play a role in the development of interstitial fibrosis in proteinuric states.
Reaction of trimethylaluminum with crown ethers. IV: Crystal structure of (18-crown-6) tetrakis-(trimethylaluminum)-p-xylene solvate

The title compound was prepared by the addition of A1Me3 to a suspension of 18-crown-6 inp-xylene. The large, colorless, air-sensitive crystals belong to the monoclinic space group P21/n witha=14.822(6),b=7.894(4),c=18.805(6) A,β=105.40(4)°, andDcalc=1.03 g cm−3 forZ=2. The finalR value based on 1758 observed reflections is 0.043. The molecule lies on a crystallographic inversion center and exhibits four strong Al-O bonds. The two independent Al-O distances are 1.978(3) and 2.000(3) A. The oxygen atoms deviate from the mean plane of the crown, alternating above and below, by 0.13, 0.15, and 0.20 A, respectively. Thep-xylene molecule is also positioned about a center of inversion.
Actions of polyamines on lipid and glucose metabolism of fat cells.

Summary Incubation of isolated rat fat cells with insulin, spermidine or spermine stimulated conversion of glucose to carbon dioxide and inhibited lipolysis. The effects of the polyamines were observed in a concentration range of 1.0 to 50 μM. At the higher concentrations of spermidine and spermine, enhanced glucose oxidation and suppressed lipolysis were essentially identical to the maximal effects produced by insulin. Putrescine possessed no insulin-like properties. The rate of glucose utilization was not increased by insulin or spermidine when the glucose concentration was greater than 30 mM. Polyamine-stimulated glucose oxidation was inhibited by phloretin and 3-0-methyl-D-glucose. Spermidine suppressed lipolysis induced by epinephrine or theophylline but the inhibitory effect was absent when lipolysis was stimulated by dibutyryl cyclic AMP. These observations suggest that in fat cells polyamines, like insulin, inhibit lipolysis by suppressing cyclic AMP levels and facilitate glucose transport.
Targeted Therapy for Kaposi Sarcoma

Kaposi sarcoma (KS) occurs as a result of Kaposi sarcoma-associated herpesvirus (KSHV) infection, typically in the context of one of several immunodeficient states. In the US, patients with KS may either be co-infected with HIV or receiving immunosuppressant therapy following solid-organ transplantation. Systemic treatment of KS has traditionally involved one of several chemotherapeutic agents administered either in combination or as single agents, which typically provide reasonable response rates and short-term control. However, recurrence of KS is common, and progression-free intervals are under 1 year. For these reasons, new therapies have been sought and with the elucidation of novel pathogenic mechanisms of KS infection, rational therapeutic targets have been identified. These include KSHV replication, restoration of immune competence, and signal transduction pathways utilized by KSHV in the propagation of KS. This review focuses on these emerging targets in the treatment of patients with KS and also highlights important clinicopathologic characteristics.
Deep shading buffers on commodity GPUs

Real-time rendering with true motion and defocus blur remains an elusive goal for application developers. In recent years, substantial progress has been made in the areas of rasterization, shading, and reconstruction for stochastic rendering. However, we have yet to see an efficient method for decoupled sampling that can be implemented on current or near-future graphics processors. In this paper, we propose one such algorithm that leverages the capability of modern GPUs to perform unordered memory accesses from within shaders. Our algorithm builds per-pixel primitive lists in canonical shading space. All shading then takes place in a single, non-multisampled forward rendering pass using conservative rasterization. This pass exploits the rasterization and shading hardware to perform shading very efficiently, and only samples that are visible in the final image are shaded. Last, the shading samples are gathered and filtered to create the final image. The input to our algorithm can be generated using a variety of methods, of which we show examples of interactive stochastic and interleaved rasterization, as well as ray tracing.
A Ferret Model of Canine Distemper Virus Virulence and Immunosuppression

Canine distemper virus (CDV) infects many carnivores, including ferrets and dogs, and is the member of the Morbillivirus genus most easily amenable to experimentation in a homologous small-animal system. To gain insights into the determinants of CDV pathogenesis, we isolated a strain highly virulent for ferrets by repeated passaging in these animals. Sequence comparison of the genome of this strain with that of its highly attenuated precursor revealed 19 mutations distributed almost evenly in the six genes. We then recovered a virus from a cDNA copy of the virulent CDV strain's consensus sequence by using a modified reverse genetics system based on B cells. We infected ferrets with this virus and showed that it fully retained virulence as measured by the timing of rash appearance, disease onset, and death. Body temperature, leukocyte number, lymphocyte proliferation activity, and cell-associated viremia also had similar kinetics. We then addressed the question of the relative importance of the envelope and other viral constituents for virulence. Viruses in which the envelope genes (matrix, fusion, and hemagglutinin) of the virulent strain were combined with the other genes of the attenuated strain caused severe rash and fever even if the disease onset was delayed. Viruses in which the nucleocapsid, polymerase, and phosphoprotein genes (coding also for the V and C proteins) of the virulent strain were combined with the envelope genes of the attenuated strain caused milder signs of disease. Thus, virulence-inducing mutations have accumulated throughout the genome.
Molecular Epidemiology and Mechanisms of Carbapenem Resistance in Acinetobacter baumannii Endemic in New York City

Multidrug-resistant Acinetobacter baumannii has emerged as a serious nosocomial pathogen in certain areas. In Brooklyn, New York, citywide surveillance revealed that approximately 2 of every 3 isolates were resistant to carbapenem antibiotics. Genetic fingerprinting revealed that 2 strains accounted for 82% of these resistant isolates. Compared with carbapenem-susceptible isolates, carbapenem-resistant isolates had reduced expression of 47-, 44-, and 37-kDa outer-membrane proteins. No specific carbapenemase was found; however, carbapenem-resistant isolates expressed greater levels of a class C cephalosporinase. Although expression of penicillin-binding proteins varied among strains, no consistent pattern appeared to account for carbapenem resistance. An efflux pump, present in several strains, did not appear to contribute to carbapenem resistance. Clonal spread of carbapenem-resistant A. baumannii has occurred in hospitals in Brooklyn. The preliminary findings for a small number of strains suggest that diminished production of outer-membrane porins, together with increased expression of a class C cephalosporinase, appear to be important factors leading to carbapenem resistance in this region.
Toxicology of Plutonium

Publisher Summary This chapter discusses the three most common routes by which plutonium enters the body—the gastrointestinal tract, the respiratory tract, and wounds in the skin. It also discusses how the physicochemical properties of the plutonium compound deposited determine its toxicological properties. Deposited in skin, in wounds, in the gastrointestinal tract, or in the respiratory tract, plutonium can be transported by the blood or lymphatic system to other organs and tissues of the body. The rate and amount of translocation depend on the site of deposition and also on the physical and chemical properties of the plutonium compound. Plutonium absorbed from the gastrointestinal tract is deposited primarily in bone, and to a lesser extent, in liver, similar to monomeric plutonium injected intravenously. The deposition of plutonium in the respiratory tract is determined by aerodynamic and physiological factors common to inhalation of any material. High concentrations of plutonium in bone cause severe skeletal changes in addition to the hematopoietic effects. Liver accumulates the highest concentrations of systemic plutonium. Deposition of large quantities of plutonium in lungs causes severe inflammatory reactions in the lung, and edema, hemorrhage, and necrosis destroying the functional tissue.
Expanding our view of authentic learning: bridging in and out-of-school experiences

In this review, I explore the affordances of Wolff-Michael Roth and Pei-Ling Hsu’s article, “Space, relations and the learning of science” which brings attention to a largely unexplored area of science education research—the importance of spatial organization within the laboratory. This forum piece examines the four components of authentic learning and how these components relate to the experiences presented in the original article. Then, it highlights the differences for in and out-of-school experiences as they relate to both authentic learning and episodes presented by Roth and Hsu.
POMC-derived peptide immunoreactivity in neural lobe axons of the human pituitary

Abstract The efferent projections of proopiomelanocortin (POMC) neurons in the arcuate nucleus and nucleus of the solitary tract have been extensively characterized in the rat, but are less well understood in the human brain. We report here that ACTH, α-MSH, β-endorphin, and N- acetyl -β- endorphin immunoreactive axons are localized in the neural lobe of the human pituitary gland, in congruence with prior evidence that β-endorphin and other POMC-derived peptides modulate vasopressin and oxytocin secretion.
Characterization of inhibitors of cellulose synthesis in cotton fibers.

Several compounds were tested for their ability to inhibit the in-vivo synthesis of cellulose and other cell-wall polysaccharides in fibers of cotton (Gossypium hirsutum L.) developing on in-vitro cultured ovules. Inhibitory effects were measured by the ability of the compounds to inhibit the incorporation of radioactivity from [U-14C]glucose into these cell-wall polymers. Of the compounds surveyed, 2,6-dichlorobenzonitrile (DCB) was the most effective and specific one for its effects on cellulose synthesis when compared to its effect on the synthesis of other cell-wall components. At 10 μM DCB caused 80% inhibition of cellulose synthesis, and the effect was reversed upon removal of the DCB, with recovery to 90% of the control rate. Two analogs of DCB, 2-chloro-6-fluorobenzonitrile and 2,6-dichlorobenzene carbothiamide, were as specific and nearly as effective as DCB with respect to their effects on cellulose synthesis. Coumarin, generally regarded as an inhibitor of cellulose synthesis in other plant systems, was effective in cotton fibers in millimolar concentrations and, like DCB, was relatively specific with regard to its effect on cellulose synthesis. DCB and coumarin inhibited the synthesis of both primary and secondary wall cellulose. Bacitracin, an inhibitor of the cycling of phosphorylated polyprenols involved in cell-wall synthesis in bacteria, and ethylenediaminetetracetic acid (EDTA) and ethyleneglycol-bis-(β-amino-ethylether)-N,N′-tetracetic acid (EGTA), chelators of civalent cations, were also effective, although only at relatively high concentrations, in inhibiting incorporation of radioactivity into cellulose.
Observational assessment of forceful exertion and the perceived force demands of daily activities

The primary objective of this study was to assess the accuracy and precision with which analysts observe and estimate the force produced as subjects performed exertions on a work simulator. Eight analysts observed 32 subjects and estimated force as a percent of subjects' maximum voluntary contraction (% MVC). Analysts exhibited bias toward the mean, as high force exertions (>67% MVC) were underestimated (mean: 11.6% MVC) and low force exertions (<34% MVC) were overestimated (mean: 6.7% MVC). Average error for medium force exertions (34–67% MVC) was not statistically different from zero (2.1% MVC). For all force levels, precision of the estimate was very poor (standard deviation range: 16.2–20.7% MVC). Experience of the analyst in performing ergonomic analysis did not affect accuracy. A secondary objective of the study was to conduct a survey in which subjects identified activities of daily living they perceived as equivalent to controlled force levels. A total of 59 different activities ranging from minimal force required to near maximum were listed by at least 5% of the participants. This list may be used to assist health care practitioners and patients convey the force demands required of occupational tasks as well as for evaluating the diminished strength of the patient.
Miocene potassium metasomatism, Whipple Mountains, southeastern California: A datable tracer of extension-related fluid transport

Potassium enrichment within the upper plate of the Whipple detachment fault, southeastern California, occurred as a discrete pulse between 18.5 and 14 Ma, following the most intense extension and prior to the last episode of movement on the detachment fault. This timing is not consistent with a hydrothermal model for K enrichment in which the K is derived from propylitic alteration of lower-plate rocks. Instead, the temporal and spatial distribution of K enrichment supports a diagenetic model in which the K was derived from leaching of Tertiary alkalic volcanic rocks and dissolution of rhyolitic ashes by alkaline-saline brines in a lake and circulating ground water. The most intense alteration is commonly associated with mapped upper-plate faults, although not all mapped faults display evidence of K metasomatism. Fracture porosity present along active faults may have provided a conduit for K-bearing fluids, thus marking a set of faults as coeval and cogenetic.
Computer model of a porous medium

A computer model has been set up to represent a porous medium. The basis for this model is a two-dimensional square network (100×100) of channels that have randomly assigned widths between the value of zero (closed) and the value of one (open, unrestricted flow). The channel width assignments have been made by a random selection from five different distributions:f(q)=q, f(q)=sinq, f(q)=erf(q),f(q)=1−sinq, andf(q)=1 −erf(q). Diffusion of particles in the network has been studied by a random-walk procedure for each realization of the channel width assignments. The diffusivity is quite sensitive to the distribution of channel widths. The percolation properties of the networks obtained from the three most restrictive distributions have been investigated and the independent, linked clusters within the network have been determined. For cluster sizes that are less than the full width of the network, the network does not percolate and either the flow is not diffusive or the diffusivity is severely reduced. An approximate value for the percolation threshold has been determined in each case and the fractal dimension has been calculated also.
Talking bodies: Body talk at bodyworks

Storytelling is a prominent feature of everyday discourse, and the growing literature on this aspect of communication indicates that stories are used to accomplish a number of interaction goals. This ethnography, completed over a seven‐month period, focused on the role of storytelling in womens’ conversations at a popular fitness facility. Of specific interest were the interpretive themes that emerged over time as consistent elements of the conversations among bodyworkers. These themes and the stories that describe them formed the substance of this report.
The univariate moving window spectral method

A major difficulty encountered in time series analysis is the bias in model parameter estimates, resulting in multiple-period lead time forecast error divergence. An approach, which mitigates the effect of this bias, is described. The spectral approach offers the potential for better estimation of cyclical components in time series. When recombined by the moving window spectral (MWS) paradigm, better long range forecast, are possible. Illustration is by comparisons to 24 other models, applied to complex non-linear multiple component time series, and 111 empirical time series. The MWS method requires the least user expertise, it explains, and it forecasts the time series the best. It is applicable to a broad range of time series associated with the physical, economic, and social sciences.
Search for genes involved in Joubert syndrome: Evidence that one or more major loci are yet to be identified and exclusion of candidate genes EN1, EN2, FGF8, and BARHL1

Joubert syndrome (JS) is a rare autosomal recessive malformation syndrome involving agenesis or dysgenesis of the cerebellar vermis with accompanying brainstem malformations. JS is further characterized by hypotonia, developmental delay, intermittent hyperpnea, and abnormal eye movements. The biochemical and molecular basis of JS remains unknown, although several genes that are crucial in the development of the cerebellum have been proposed as attractive candidate genes. JS is clinically heterogeneous; this, together with previous linkage analyses, suggests that there may also be genetic heterogeneity. A locus for JS was previously identified on chromosome 9q34 by linkage analysis in a consanguineous family of Arabian origin. A putative second JS locus was recently suggested when a deletion on chromosome 17p11.2 was observed in a patient with Smith-Magenis syndrome and JS phenotype. We have investigated a cohort of apparently unrelated North American JS pedigrees for association with the loci on chromosomes 9q34 and 17p11.2 and excluded them in all cases where data were informative. Analysis of an additional 21 unrelated JS patients showed no evidence of homozygosity at the 9q34 and 17p11.2 loci that would suggest inheritance of founder JS mutation(s) or unreported consanguinity. Together, these data suggest that one or more major loci for JS remain to be identified. Consequently, we undertook mutation analysis of several functional candidate genes, EN1, EN2, and FGF8, in a total of 26 unrelated JS patients. Our data suggest that all of these genes may be excluded from a direct pathogenic role in JS. The BARHL1 gene, which localizes to chromosome 9q34 and has previously been proposed as a strong positional candidate gene for JS, was also investigated and excluded from involvement in JS that is linked to chromosome 9q34.
Direct observation of sulfur dimers in alkanethiol self-assembled monolayers on Au(111)

High-resolution electron-energy-loss spectra of octadecanethiol self-assembled monolayers (SAM's) on Au thin films have been obtained after annealing the sample to various temperatures. Annealing to 375 K results in the appearance of the S-S stretch at 530 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$, a direct observation of sulfur dimers for alkanethiol SAM's adsorbed on Au. The appearance of dimers following annealing is explained by the presence of an activation barrier to the formation of gauche defects at the S-C bond.
Analyses of MbtB, MbtE, and MbtF Suggest Revisions to the Mycobactin Biosynthesis Pathway in Mycobacterium tuberculosis

The production of mycobactin (MBT) by Mycobacterium tuberculosis is essential for this bacterium to access iron when it is in an infected host. Due to this essential function, there is considerable interest in deciphering the mechanism of MBT assembly, with the goal of targeting select biosynthetic steps for antituberculosis drug development. The proposed scheme for MBT biosynthesis involves assembly of the MBT backbone by a hybrid nonribosomal peptide synthetase (NRPS)/polyketide synthase (PKS) megasynthase followed by the tailoring of this backbone by N(6) acylation of the central l-Lys residue and subsequent N(6)-hydroxylation of the central N(6)-acyl-l-Lys and the terminal caprolactam. A complete testing of this hypothesis has been hindered by the inability to heterologously produce soluble megasynthase components. Here we show that soluble forms of the NRPS components MbtB, MbtE, and MbtF are obtained when these enzymes are coproduced with MbtH. Using these soluble enzymes we determined the amino acid specificity of each adenylation (A) domain. These results suggest that the proposed tailoring enzymes are actually involved in precursor biosynthesis since the A domains of MbtE and MbtF are specific for N(6)-acyl-N(6)-hydroxy-l-Lys and N(6)-hydroxy-l-Lys, respectively. Furthermore, the preference of the A domain of MbtB for l-Thr over l-Ser suggests that the megasynthase produces MBT derivatives with β-methyl oxazoline rings. Since the most prominent form of MBT produced by M. tuberculosis lacks this β-methyl group, a mechanism for demethylation remains to be discovered. These results suggest revisions to the MBT biosynthesis pathway while also identifying new targets for antituberculosis drug development.
Ion steric effects on electrophoresis of a colloidal particle

We calculate the electrophoretic mobility Me of a spherical colloidal particle, using modified Poisson–Nernst–Planck (PNP) equations that account for steric repulsion between finite sized ions, through Bikerman's mean-field model (Bikerman, Phil. Mag., vol. 33, 1942, p. 384). Ion steric effects are controlled by the bulk volume fraction of ions ν, and for ν = 0 the standard PNP equations are recovered. An asymptotic analysis in the thin-double-layer limit reveals at small zeta potentials (ζ < kBT/e ≈ 25 mV) Me to increase linearly with ζ for all ν, as expected from the Helmholtz–Smoluchowski (HS) formula. For larger ζ, however, it is well known that surface conduction of ions within the double layer reduces Me below the HS result. Crucially, however, in the PNP equations surface conduction becomes significant precisely because of the aphysically large and unbounded counter-ion densities predicted at large ζ. In contrast, ion steric effects impose a limit on the counter-ion density, thereby mitigating surface conduction. Hence, Me does not fall as far below HS for finite sized ions (ν ≠ 0). Indeed, at sufficiently large ν, ion steric effects are so dramatic that a maximum in Me is not observed for physically reasonable values of ζ(≤ 10 kBT/e), in stark contrast to the PNP-based calculations of O'Brien & White (J. Chem. Soc. Faraday Trans. II, vol. 74, 1978, p. 1607) and O'Brien (J. Colloid Interface Sci., vol. 92, 1983, p. 204). Finally, by calculating a Dukhin–Bikerman number characterizing the relative importance of surface conduction, we collapse Me versus ζ data for different ν onto a single master curve.
Information Access versus Document Supply: The International Visual Arts Information Network Project

Image content opens up exciting possibilities for stand‐alone media, distributed networks, on‐line networks and on‐site publishing from information systems for use by the general public, for research, collection management, education and distance learning. These developments coincide and overlap with widespread new questioning and thinking as to the role of museums in relation to their diverse publics and also have many parallels in the library world. They raise difficult questions about intellectual property rights – copyright protection, fair remuneration and complex questions concerning moral rights. Clearly international co‐operation, working partnerships and consortia are going to gain further importance and significance.
Constraints on generalized inflationary cosmologies

Abstract We consider cosmologies having an inflationary period during which the Robertson-Walker scale factor is an arbitrary function of time satisfying R > 0 (not necessarily an exponential). We show that any such inflationary period will produce long-wavelength gravitational waves which can affect present observations of the microwave background. Using present bounds on the quadrupole anisotropy we derive constraints on general background. Using present bounds on the power law inflation (R ∼ tp) are considered in detail and the maximum reheating temperature is given as a function of p. Finally, predictions for the anisotropy of the microwave background produced by gravitational waves generated by ordinary exponential inflation are presented.
Design and conduct of a windshear detection flight experiment

A description is presented of the design and conduct of a series of flight experiments that tested the performance of candidate windshear detection devices. A NASA 737 test aircraft with prototype windshear sensors installed flew numerous low altitude penetrations of microburst windshear conditions. These tests were preceded by extensive preparations including piloted simulations, determination of safe operating conditions, and the development of displays, unique flight test hardware, and procedures.
Acoustic similarity and retroactive interference in short-term memory

Summary Short-term memory for a list of four letters, followed by a list of eight letters that the S s copied as they were presented, followed by immediate recall of the original four-letter list, was shown to be a function of the acoustic similarity of the intervening list to the original list. An interfering list whose letters have similar pronunciation to the letters in the original list produces greater RI than an interfering list whose letters have a very different pronunciation from the letters in the original list. An interfering list composed of items identical to items in the original list, but in a different order, tends to produce less RI in the recall of items and more RI in the recall of the correct position of these items than an interfering list composed of similar items. These findings for STM are completely consistent with analogous studies of RI as a function of similarity in LTM.
PROPERTIES OF BL LAC OBJECTS

The properties of BL Lacertae objects are examined in light of their recently realized similarities to quasars and associations with galactic radiation. The criteria typically used to define BL Lac objects are analyzed, with attention given to radio spectra, optical continual, radio and optical variability, optical polarization and emission lines, and evidence that BL Lac objects and optically violent variables represent the most compact and strongly variable sources among the general class of quasars is discussed. Connections between BL Lac objects and the galaxies in which they have been observed to be embedded are discussed and it is pointed out that no low-luminosity quasars have been found to be associated with first-ranked giant ellipticals. Future observations which may clarify the properties and relationships of BL Lac objects are indicated.
Homocub-1(9)-ene trapped

Decomposition of the tosylhydrazone salts formed from cubyl carboxaldehyde and homocubanone, potential precursors of cubylcarbene (5) and homocubanylidene (6), leads in each case to products derived from 6. It is suggested that homocub-1(9)-ene (7) is the active ingredient in the formation of 6 from both precursors. The hydrazones formed from N-aziridylamines are useful photochemical sources of 6, and presumably other carbenes. Flash vacuum pyrolysis of the tosyl hydrazone salts and hydrazones at 600°C leads to indene.
Irrigation timing of three landscape shrub species based on foliage temperature

Summary Changes in foliage temperature with vapour pressure deficit and water stress for three shrub species were investigated for use in irrigation scheduling in landscapes. Midday leaf-minus-air temperature (T1-Ta) and vapour pressure deficit were monitored seasonally for prostrate juniper (Juniperus horizontalis ‘Wiltonii’), upright juniper (J. chinensis ‘Hetzi’, and dwarf red-stem dogwood (Cornus sericea ‘Kelseyii’), positioned as isolated plants or in a massed setting. There was an inverse baseline relationship between T1-Taand vapour pressure deficit for all species and both spacings under well-watered conditions. This was consistent with baselines reported for herbaceous crops, but with substantially more scatter. Baseline relationships between spacings were similar for upright juniper and dogwood, but not for prostrate juniper. During a dry-down cycle T1-Ta exceeded the well-watered baseline for dogwood and upright juniper, signalling incipient water stress. Stress was confirmed in declining preda...
Microindentation fatigue tests on submicron carbon films

Abstract Microindentation fatigue tests have been conducted on submicron coatings using a microindenter. The cyclic indentation was implemented by servo controlling the motion of the indenter so that the loadcell output followed a 0.1 Hz sinusoidal loading pattern. A conical diamond indenter with a nominal 1 μm tip radius was used. A model system composed of two 0.11 μm sputtered carbon films was chosen for investigating the indentation fatigue effects on brittle coatings. Both carbon films were deposited on silicon substrates but with substantially different interfacial adhesion strengths. For the carbon film with poor adhesion tested at the condition of a 4 mN maximum load, an annular coating buckling pattern concentric with the center of the indent appeared during the first loading stage whereas coating spallation occurred at loading cycle numbers ranging from 50 to 140. In contrast to this, under the same test condition, the carbon coating with good adhesion did not show any noticeable failure up to 500 cycles where the experiments were truncated. When the maximum load was increased, fine cracks initiated in the carbon coating and along the circular indent boundaries but the coating still adhered well to the substrate. These fine cracks continued to propagate during subsequent indentations, and eventually spallation of the carbon coating occurred. Because the microindenter has the advantage of continuously monitoring both the applied load and penetration depth during an entire test, the evolution of the fatigue failure of a coating system can be clearly visualized from the corresponding load vs. depth curve. A typical brittle failure event is manifested by several repeatable loading-unloading cycles with a gradual depth increase after the first indentation, then a couple of consecutive abrupt changes in the applied load as well as in the depth followed by stabilized indentation cycles.
Prolonged periods without food intake during pregnancy increase risk for elevated maternal corticotropin-releasing hormone concentrations.

Abstract Objective: Fasting during pregnancy stimulates preterm delivery in animals and increases women's risk for preterm delivery. Fasting stimulates hypothalamic corticotropin-releasing hormone production in animals. Elevated maternal corticotropin-releasing hormone concentrations are associated with preterm birth. We hypothesized that prolonged periods without food during pregnancy increase maternal corticotropin-releasing hormone concentrations, which lead to preterm delivery. Study Design: In the Behavior in Pregnancy Study, we examined prolonged periods without eating during pregnancy and corticotropin-releasing hormone concentrations and gestational age at delivery with multivariate logistic regression analysis (n = 237). Results: Prolonged periods without food lasting 13 hours or longer were associated with elevated maternal corticotropin-releasing hormone concentrations compared with prolonged periods without food lasting less than 13 hours at two time points during pregnancy, controlling for pregravid body mass index, energy intake, income, race, smoking, and maternal age (18-20 weeks: adjusted odds ratio, 2.5; 95% CI, 0.9-7.1; 28-30 weeks: adjusted odds ratio, 1.7; 95% CI, 0.7-4.2). There was an inverse, linear relationship between maternal corticotropin-releasing hormone concentrations and gestational age at delivery. Conclusions: Prolonged periods without food intake during pregnancy are associated with elevated maternal corticotropin-releasing hormone concentrations and with preterm delivery. (Am J Obstet Gynecol 2001;185:403-12.)
A fracture mechanics life prediction methodology applied to dovetail fretting

This work evaluates a fracture mechanics based crack growth life prediction methodology for dovetail fretting fatigue laboratory experiments. The Ti-6Al-4V specimens were configured with angles of 35°, 45° and 55°. Experiments were conducted with constant amplitude loading at R of 0.1 and 0.5 with lives ranging from 100,000 to 10 million cycles. The approach included the contact loads and bulk stress calculated from the finite element method as inputs to the stress and life analysis. Contact stresses were calculated using the contact stress analysis software CAPRI. These stresses were input into a stress intensity factor calculation at the edge of contact. Crack propagation life was calculated from an assumed initial crack size. Analysis showed that propagation consumes a majority of the total life and is insensitive to a large range of initial crack sizes.
The Amyloid Precursor Protein Has a Flexible Transmembrane Domain and Binds Cholesterol

C99 is the transmembrane carboxyl-terminal domain of the amyloid precursor protein that is cleaved by γ-secretase to release the amyloid-β polypeptides, which are associated with Alzheimer’s disease. Nuclear magnetic resonance and electron paramagnetic resonance spectroscopy show that the extracellular amino terminus of C99 includes a surface-embedded “N-helix” followed by a short “N-loop” connecting to the transmembrane domain (TMD). The TMD is a flexibly curved α helix, making it well suited for processive cleavage by γ-secretase. Titration of C99 reveals a binding site for cholesterol, providing mechanistic insight into how cholesterol promotes amyloidogenesis. Membrane-buried GXXXG motifs (G, Gly; X, any amino acid), which have an established role in oligomerization, were also shown to play a key role in cholesterol binding. The structure and cholesterol binding properties of C99 may aid in the design of Alzheimer’s therapeutics.
The proximal sequence element (PSE) plays a major role in establishing the RNA polymerase specificity of Drosophila U-snRNA genes

Most small nuclear RNA (snRNA) genes are transcribed by RNA polymerase II, but some (e.g., U6) are transcribed by RNA polymerase III. In vertebrates a TATA box at a fixed distance downstream of the proximal sequence element (PSE) acts as a dominant determinant for recruiting RNA polymerase III to U6 gene promoters. In contrast, vertebrate snRNA genes that contain a PSE but lack a TATA box are transcribed by RNA polymerase II. In plants, transcription of both classes of snRNA genes requires a TATA box in addition to an upstream sequence element (USE), and polymerase specificity is determined by the spacing between these two core promoter elements. In these examples, the PSE (or USE) is interchangeable between the two classes of snRNA genes. Here we report the surprising finding that the Drosophila U1 and U6 PSEs cannot functionally substitute for each other; rather, determination of RNA polymerase specificity is an intrinsic property of the PSE sequence itself. The alteration of two or three base pairs near the 3'-end of the U1 and U6 PSEs was sufficient to switch the RNA polymerase specificity of Drosophila snRNA promoters in vitro. These findings reveal a novel mechanism for achieving RNA polymerase specificity at insect snRNA promoters.
The Technological Development of Congressional Candidate Websites: How and Why Candidates Use Web Innovations

The Internet offers political candidates a new way to campaign. Part of the Internet’s novelty comes from technological options not available in most other media. Candidates, however, must weigh various benefits and costs in using a given technological innovation. For example, technology that allows for increased user interactivity may lead to a more stimulating web site but might distract users from the campaign’s central message. In this article, the authors use data from 444 congressional campaign web sites, over two elections, to examine how candidates approach web technology. They investigate the factors that lead candidates to utilize or avoid particular technological features. They show that technological adoption is determined by both practical and strategic political considerations. Of particular interest, the competitiveness of a candidate’s race leads the candidate to use more sophisticated presentation technologies but less advanced interactive innovations because these latter options interfere with the candidate’s message.