Influence of a Phase Transition of Ice on the Heat and Mass Balance of Comets

Differences in gas production rates of comets may be explained in part by the phase transition of ice in the comet nuclei.

Pseudomonas cepacia typing systems: collaborative study to assess their potential in epidemiologic investigations

To determine the utility of available Pseudomonas cepacia typing systems for confirming the relatedness of isolates, we applied these methods to isolates associated with previously investigated nosocomial outbreaks. We compared chromosome analysis, serologic reactions, biochemical tests, bacteriocin production and susceptibility, and antimicrobial susceptibility in their ability to determine outbreak relatedness. Chromosome analysis, serologic reactions, and biochemical tests were each demonstrated to be epidemiologically useful methods for typing isolates. Determination of the sensitivity and specificity of these typing techniques will facilitate their application in the epidemiologic study of this increasingly important nosocomial pathogen.

Refraction and its components in Melanesian schoolchildren in Vanuatu

Refraction and its components were measured on 788 Melanesian children and 39 children of other races, aged 6 through 19 years, in the South Pacific island nation of Vanuatu. Of the 788 Melanesian children, 766 (97.2%) were found to have uncorrected visual acuity of 6/6 or better, and 763 (96.8%) were found to have a spherical equivalent refraction between -0.25 and +1.00 D. Only 23 (2.9%) Melanesian children were found to have myopia greater than 0.25 D, only 2 (0.3%) were found to have hyperopia greater than 1.00 D, and only 2 (0.3%) were found to have refractive astigmatism greater than 1.00 D. Mean corneal refracting power was greater for girls than for boys, at all ages, but did not appear to change in any regular manner with age. Mean axial length and mean vitreous length were greater for boys than for girls, at all ages, each increasing approximately 1.0 mm from age 6 and 7 years to age 18 and 19 years. Although the low prevalence of ametropia may be considered to be due mainly to genetic factors, the possibility of environmental factors cannot be excluded.

Immunological capture of nucleic acid hybrids and application to nonradioactive DNA probe assay

Antibodies specific for DNA:RNA hybrids were coated onto polystyrene test tubes and applied to hybridization assays involving DNA and RNA. Synthetic DNA probes complementary to 16S rRNA of Campylobacter were labeled with biotin and hybridized to ribosomal RNA directly in lysates of bacterial cells. After hybridization, DNA:RNA hybrids were captured with immobilized anti-DNA:RNA antibody, and the biotinylated probe was detected with streptavidin-horseradish peroxidase (EC 1.11.1.7) conjugate. The assay was optimized to detect as few as 70,000 Campylobacter cells in a sample. We compared the utility of this hybridization assay with that of conventional microbiology methods by examination of 1448 stool samples from hospital clinical laboratories. The DNA hybridization assay had a sensitivity of 98.7% (75/76) and a specificity of 98.2% (1347/1372) and overall agreed with 98.2% of the conventional results for a test population that had a 5.2% incidence (76/1448) of Campylobacter infection. The assay is simple to perform and yields results within 2.5 h.

Ultra-narrow linewidth, stable and tunable laser source for optical communication systems and spectroscopy

A novel ultra-narrow linewidth, stable and tunable single-line laser source is demonstrated and experimentally performed. The single spectral line laser is achieved by selecting and amplifying one spectral comb line of a femtosecond-fiber laser via polarization pulling assisted stimulated Brillouin scattering. Stabilization and tuning is performed by additional modulation. First proof of concept results show possible linewidths below 1 Hz and an SNR of 47 dB with a tunability of more than 100 nm and a relative stability of ±160  mHz over 5 h. Such a laser source gives high potential for many different applications like spectroscopy and optical communications.

Simultaneous determination of lidocaine and its metabolites in plasma and myocardium

No validated method exists for measuring lidocaine and its metabolites in myocardial tissue. We modified a previously described high-performance liquid chromatographic assay and applied it to plasma and to homogenized myocardial samples obtained from dogs that had received lidocaine by a double-infusion technique. Recovery of lidocaine, monoethylglycylxylidide and glycylxylidide after homogenization and extraction is reported. Assay variability, sensitivity and linearity over a wide range of sample sizes are also described. The results obtained with high-performance liquid chromatographic analysis are compared to quantitation of 14C-labeled lidocaine plus metabolites measured by an oxidation-scintillation technique. Myocardium to plasma partition coefficients for lidocaine, monoethylglycylxylidide and glycylxylidide were 2.16, 4.27, and 2.91, respectively.

Lipid solubility modulates pH potentiation of local anesthetic block of Vmax reactivation in guinea pig myocardium

Current theories envision recovery from local anesthetic block of sodium channels via slow hydrophilic and fast hydrophobic paths. Extracellular pH reduction which increases cationic/neutral anesthetic form should especially prolong recovery kinetics of highly lipid soluble compounds that could readily exit via the hydrophobic pathway at normal extracellular pH. To test this hypothesis, we compared the effects of three related compounds with similar pKa on the time course of Vmax reactivation in guinea pig papillary muscle at pHo 7.4 and 6.95. The compounds were lidocaine and its two desethylation products, monoethylglycinexylidide and glycinexylidide. Judged from the octanol:water partition coefficient, lidocaine was the most lipid soluble (log partition coefficient 2.39 +/- 0.10), followed by monoethylglycinexylidide (log partition coefficient 1.32 +/- 0.09) and glycinexylidide was the least lipid soluble (log partition coefficient 0.41 +/- 0.09). At 30 microM and pHo 7.4, the potency order for Vmax depression at zero diastolic interval was lidocaine (53 +/- 6%), monoethylglycinexylidide (17 +/- 3%), and then glycinexylidide (7.8 +/- 1.9%). The decay of Vmax block appeared monoexponential, and the time constant of recovery was dose independent. Most important is the fact that there were significant differences in the tau r increase with extracellular pH reduction (P less than 0.05; Scheffé contrasts). The increase was greatest with lidocaine [73 +/- 28% (mean +/- SD)], less with monoethylglycinexylidide (42 +/- 15%), and least with glycinexylidide (13 +/- 17%). The simplest interpretation of the differences in extracellular pH-dependence of recovery kinetics was that recovery from block due to the neutral form of these ionizable local anesthetics depended on lipid solubility, whereas recovery from block due to the protonated form depended on molecular weight.

Experiments on induced modulational instability of an incoherent optical beam

We report the observation of modulational instability (MI) of a partially spatially incoherent beam induced by seeding noise through cross-phase modulation. We show experimentally that a threshold exists for such induced incoherent MI to occur that depends on the degree of spatial coherence as well as on the strength of the nonlinearity. Above threshold, the induced MI leads to the formation of ordered and disordered patterns of incoherent light.

Molecular cloning of the human immunodeficiency virus subtype 2 strain HIV-2UC2

An infectious molecular clone was derived from the HIV-2UC2 isolate that previously was found to persistently infect and induce an AIDS-like disease syndrome in baboons. The molecularly cloned virus (HIV-2UC2mc) showed in vitro properties similar to those of the parental isolate with regard to T-cell tropism, cytopathicity, and the ability to infect primary baboon PBMC. Nevertheless, when inoculated into two baboons, the cloned virus showed a limited ability to replicate in these animals. DNA sequence analysis revealed a defective vpr gene in the UC2mc as well as in the pathogenic parental UC2 strain. Thus, the vpr gene is not required for the induction of disease in baboons. The attenuated infectious molecular clone of UC2 should be useful for future studies designed to map the genetic determinants of HIV-2 pathogenesis in the baboon model and to evaluate vaccine strategies.

Exaggerated pulmonary hypertension with monocrotaline in rats susceptible to chronic mountain sickness

Hilltop (H) strain Sprague-Dawley rats are more susceptible to chronic mountain sickness than are the Madison (M) strain rats. It is unclear what role pulmonary vascular remodeling, polycythemia, and hypoxia-induced vasoconstriction play in mediating the more severe pulmonary hypertension that develops in the H rats during chronic hypoxia. It is also unclear whether the increased sensitivity of the H rats to chronic mountain sickness is specific for a hypoxia effect or, instead, reflects a general propensity toward the development of pulmonary hypertension. Monocrotaline (MCT) causes pulmonary vascular remodeling and pulmonary hypertension. We hypothesized that the difference in the pulmonary vascular response to chronic hypoxia between H and M rats reflects an increased sensitivity of the H rats to any pulmonary hypertensive stimuli. Consequently, we expected the two strains to also differ in their susceptibility to MCT-induced pulmonary hypertension. Pulmonary arterial pressures in conscious H and M rats were measured 3 wk after a single dose of MCT, exposure to a simulated high altitude of 18,000 ft (barometric pressure = 380 mmHg), and administration of a single dose of saline as a placebo. The H rats had significantly higher pulmonary arterial pressures and right ventricular weights after MCT and chronic hypoxia than did the M rats. The H rats also had more pulmonary vascular remodeling, i.e., greater wall thickness as a percentage of vessel diameter, after MCT and chronic hypoxia than did the M rats. The H rats had significantly lower arterial PO2 than did the M rats after MCT, but the degree of hypoxemia was mild [arterial PO2 of 72.5 +/- 0.8 (SE) Torr for H rats vs. 77.4 +/- 0.8 Torr for M rats after MCT]. The H rats had lower arterial PCO2 and larger minute ventilation values than did the M rats after MCT. These ventilatory differences suggest that MCT caused more severe pulmonary vascular damage in the H rats than in the M rats. These data support the hypothesis that the H rats have a general propensity to develop pulmonary hypertension and suggest that differences in pulmonary vascular remodeling account for the increased susceptibility of H rats, compared with M rats, to both MCT and chronic hypoxia-induced pulmonary hypertension.

Splitting Probabilities of Symmetric Jump Processes

We derive a universal, exact asymptotic form of the splitting probability for symmetric continuous jump processes, which quantifies the probability π_{0,[under x]_}(x_{0}) that the process crosses x before 0 starting from a given position x_{0}∈[0,x] in the regime x_{0}≪x. This analysis provides in particular a fully explicit determination of the transmission probability (x_{0}=0), in striking contrast with the trivial prediction π_{0,[under x]_}(0)=0 obtained by taking the continuous limit of the process, which reveals the importance of the microscopic properties of the dynamics. These results are illustrated with paradigmatic models of jump processes with applications to light scattering in heterogeneous media in realistic 3D slab geometries. In this context, our explicit predictions of the transmission probability, which can be directly measured experimentally, provide a quantitative characterization of the effective random process describing light scattering in the medium.

Core-binding factor leukemia hijacks the T-cell-prone PU.1 antisense promoter

The blood system serves as a key model for cell differentiation and cancer. It is orchestrated by precise spatiotemporal expression of crucial transcription factors. One of the key master regulators in the hematopoietic systems is PU.1. Reduced levels of PU.1 are characteristic for human acute myeloid leukemia (AML) and are known to induce AML in mouse models. Here, we show that transcriptional downregulation of PU.1 is an active process involving an alternative promoter in intron 3 that is induced by RUNX transcription factors driving noncoding antisense transcription. Core-binding factor (CBF) fusions RUNX1-ETO and CBFβ-MYH11 in t(8;21) and inv(16) AML, respectively, activate the PU.1 antisense promoter that results in a shift from sense toward antisense transcription and myeloid differentiation blockade. In patients with CBF-AML, we found that an elevated antisense/sense transcript and promoter accessibility ratio represents a hallmark compared with normal karyotype AML or healthy CD34+ cells. Competitive interaction of an enhancer with the proximal or the antisense promoter forms a binary on/off switch for either myeloid or T-cell development. Leukemic CBF fusions thus use a physiological mechanism used by T cells to decrease sense transcription. Our study is the first example of a sense/antisense promoter competition as a crucial functional switch for gene expression perturbation by oncogenes. Hence, this disease mechanism reveals a previously unknown Achilles heel for future precise therapeutic targeting of oncogene-induced chromatin remodeling.

Muography of different structures using muon scattering and absorption algorithms

In recent decades, muon imaging has found a plethora of applications in many fields. This technique succeeds to infer the density distribution of big inaccessible structures where conventional techniques cannot be used. The requirements of different applications demand specific implementations of image reconstruction algorithms for either multiple scattering or absorption-transmission data analysis, as well as noise-suppression filters and muon momentum estimators. This paper presents successful results of image reconstruction techniques applied to simulated data of some representative applications. In addition to well-known reconstruction methods, a novel approach, the so-called μCT, is proposed for the inspection of spent nuclear fuel canisters. Results obtained based on both μCT and the maximum-likelihood expectation maximization reconstruction algorithms are presented.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

Distribution and abundance of neutral endopeptidase (EC 3.4.24.11) in the alimentary tract of the rat

The distribution of neutral endopeptidase (NEP; EC 3.4.24.11) was examined in the alimentary tract of the rat. Immunoreactive NEP and NEP mRNA were localized to epithelial cells of the small intestine and to muscle cells in the stomach, small intestine, and colon by immunohistochemistry and in situ hybridization histochemistry. NEP antisera recognized a protein on Western blots of membranes from gastric, jejunal, and colonic mucosa and gastric muscle with an electrophoretic mobility identical to that of recombinant human NEP (approximately 95 kDa). An antisense cRNA probe to NEP hybridized to RNA of approximately 3.5 kb and approximately 6.5 kb, corresponding to the primary transcripts of rat NEP, on Northern blots of total RNA from the jejunal mucosa. NEP message was detected in mRNA from jejunal and colonic mucosa and gastric, jejunal, and colonic muscle using a ribonuclease protection assay. NEP enzymatic activity, assessed by DL-thiorphan-inhibitable degradation of glutaryl-Ala-Ala-Phe-4-methoxy-2-naphthylamine, was highest in homogenates of jejunal mucosa (868 +/- 98 pmol.h-1 x micrograms protein-1) and was between 49- and 413-fold lower in other gastrointestinal tissues. The cellular origin of NEP in the gastric and colonic mucosa could not be determined.

Distribution of the span of one-dimensional confined random processes before hitting a target

We derive the distribution of the number of distinct sites visited by a random walker before hitting a target site of a finite one-dimensional (1D) domain. Our approach holds for the general class of Markovian processes with connected span-i.e., whose trajectories have no "holes." We show that the distribution can be simply expressed in terms of splitting probabilities only. We provide explicit results for classical examples of random processes with relevance to target search problems, such as simple symmetric random walks, biased random walks, persistent random walks, and resetting random walks. As a by-product, explicit expressions for the splitting probabilities of all these processes are given. Extensions to reflecting boundary conditions, continuous processes, and an example of a random process with a nonconnected span are discussed.

Isotopic constraints on water source mixing, network leakage and contamination in an urban groundwater system

Water supply in developing countries is prone to large water losses due to leaky distribution networks and defective sewers, which may affect groundwater quality and quantity in urban areas and result in complex subsurface mixing dynamics. In this study, a multi-stable isotope approach was used to investigate spatiotemporal fluctuations of surface and sub-surface water source partitioning and mixing, and to assess nitrogen (N) contamination in the urban water cycle of As-Salt, Jordan. Water import from the King Abdullah Canal (KAC), mains waters from the network, and wastewater are characterized by distinct isotopic signatures, which allowed us to quantify city effluents into the groundwater. Temporal variations in isotopic signatures of polluted groundwater are explained by seasonally fluctuating inflow, and dilution by water that originates from Lake Tiberias and enters the urban water cycle via the KAC. Isotopic analysis (N and O) and comparison between groundwater nitrate and nitrate from mains water, water imports and wastewater confirmed that septic waste from leaky sewers is the main contributor of nitrate contamination. The nitrate of strongly contaminated groundwater was characterized by highest δ¹⁵N_NO3 values (13.3±1.8‰), whereas lowest δ¹⁵N_NO3 values were measured in unpolluted groundwater (6.9‰). Analogously, nitrate concentration and isotopic ratios were used for source partitioning and qualitatively confirmed δD_H2O and δ¹⁸O_H2O-based estimates. Dual water isotope endmember mixing calculations suggest that city effluents from leaky networks and sewers contribute 30-64% to the heavily polluted groundwater. Ternary mixing calculations including also chloride revealed that 5-18% of the polluted groundwater is wastewater. Up to two thirds of the groundwater originates from mains, indicating excessive water loss from the network, and calling for improved water supply management.

Integrating groundwater into urban water management

The management of urban groundwater resources is directly linked to urban water supply and drainage concepts. A proper integration of groundwater into urban water management plans is recommended for long-term planning. The paper describes the development of a new modelling suite which addresses the urban water and solute balance in a holistic way. Special focus has been placed on the assessment of the impact of sewer leakage on groundwater in four case study cities. Tools for the prediction of sewer leakage including the assessment of uncertainties are now available. Field investigations in four European case study cities were able to trace the influence of sewer leakage on urban groundwater using microbiological indicators and pharmaceutical residues.

Muon-Induced Neutrons Do Not Explain the DAMA Data

We present an accurate model of the muon-induced background in the DAMA/LIBRA experiment. Our work challenges proposed mechanisms which seek to explain the observed DAMA signal modulation with muon-induced backgrounds. Muon generation and transport are performed using the MUSIC/MUSUN code, and subsequent interactions in the vicinity of the DAMA detector cavern are simulated with Geant4. We estimate the total muon-induced neutron flux in the detector cavern to be Φ(n)(ν)=1.0 × 10(-9)  cm(-2) s(-1). We predict 3.49 × 10(-5)  counts/day/kg/keV, which accounts for less than 0.3% of the DAMA signal modulation amplitude.

Reaction of antibody in sera from cystic fibrosis patients with non-toxic forms of Pseudomonas aeruginosa exotoxin A

Sera from 48 cystic fibrosis patients from two hospitals were screened for antibody against rods, non-toxic macromolecular structures which share antigenic determinants with Pseudomonas aeruginosa exotoxin A. A solid-phase radioimmunoassay employing (125I)-staphylococcal protein A was used to detect anti-rod IgG. Antibodies recognizing rods, exotoxin A, or both antigens, were demonstrated using a competitive radioimmunoassay in cystic fibrosis patient sera, and in sera from animals immunized with exotoxin A, rods, or infected with Pseudomonas aeruginosa. Anti-rod titers of cystic fibrosis patients (1.07 to 14 X control serum levels) inversely correlated with aggregate clinical evaluation scores, and in most instances, with X-ray scores. Since rods are non-toxic and cross-reactive with exotoxin A, they may represent therapeutically useful antigens for producing immunity to exotoxin A.

Pharmacokinetics of human growth hormone administered subcutaneously with two different injection systems

The bioavailability of recombinant human growth hormone (somatropin, CAS 12629-01-5) was compared between a transcutaneous jet injection device and subcutaneous cannula injection. Thirteen healthy male subjects received 8.64 IU somatropin once with jet and once with cannula injection in a randomized cross-over study. Baseline-corrected somatropin serum concentrations were evaluated with non-compartmental and compartmental methods. The 90% confidence intervals with two one-sided t-tests around the ratios of injection devices were 91-120% for maximum concentration, 94-110% for area-under-curve until 14 h, and 92-103% for area-under-curve to infinity. Somatropin has a known metabolic half-life of ca. 20-30 min while the observed terminal half-lives were 2-4 h. Absorption and elimination rate constants were similar. Times of maximum concentrations, terminal half-lives and lag times to start of absorption appeared to be shorter and the absorption rate constant appeared to be larger for jet than for cannula injection. In conclusion, the kinetics of somatropin from subcutaneous tissue had a "flip-flop" characteristic. Bioavailability of somatropin after jet injection was equivalent to cannula injection.

INFN muon tomography demonstrator: past and recent results with an eye to near-future activities

A short description of the muon tomography demonstrator at the INFN Laboratori Nazionali di Legnaro near Padua, Italy, is given and the principal achievements owing to the data collected at that experimental facility are presented. In particular, the feasibility studies for several applications based on the muon-tomographic technology, within national and European projects, are discussed. The experimental problems and the procedures used to improve the performance are underlined. In addition, new activities and the related detector optimization are illustrated.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.