Measurements of Nonsinglet Moments of the Nucleon Structure Functions and Comparison to Predictions from Lattice QCD for Q

We present extractions of the nucleon nonsinglet moments utilizing new precision data on the deuteron F_{2} structure function at large Bjorken-x determined via the Rosenbluth separation technique at Jefferson Lab Experimental Hall C. These new data are combined with a complementary set of data on the proton previously measured in Hall C at similar kinematics and world datasets on the proton and deuteron at lower x measured at SLAC and CERN. The new Jefferson Lab data provide coverage of the upper third of the x range, crucial for precision determination of the higher moments. In contrast to previous extractions, these moments have been corrected for nuclear effects in the deuteron using a new global fit to the deuteron and proton data. The obtained experimental moments represent an order of magnitude improvement in precision over previous extractions using high x data. Moreover, recent exciting developments in lattice QCD calculations provide a first ever comparison of these new experimental results with calculations of moments carried out at the physical pion mass, as well as a new approach that first calculates the quark distributions directly before determining moments.

Polarization components in π0 photoproduction at photon energies up to 5.6 GeV.

We present new data for the polarization observables of the final state proton in the (1)H(γ,p)π(0) reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π(0) scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E(γ)=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π(0) scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.

Search for effects beyond the born approximation in polarization transfer observables in e(over→)p elastic scattering.

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, G(E)/G(M), obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic H(e[over →],e(')p[over →]) reaction for three different beam energies at a Q(2)=2.5 GeV(2), spanning a wide range of the kinematic parameter ε. The ratio R, which equals µ(p)G(E)/G(M) in the Born approximation, is found to be independent of ε at the 1.5% level. The ε dependence of the longitudinal polarization transfer component P(ℓ) shows an enhancement of (2.3±0.6)% relative to the Born approximation at large ε.

Measurement of the positive muon lifetime and determination of the Fermi constant to part-per-million precision.

We report a measurement of the positive muon lifetime to a precision of 1.0 ppm; it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2×10(12) decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give τ(µ(+)) (MuLan)=2 196 980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G(F) (MuLan)=1.166 378 8(7)×10(-5) GeV(-2) (0.6 ppm). It is also used to extract the µ(-)p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g(P).

Recoil polarization measurements of the proton electromagnetic form factor ratio to Q2 = 8.5 GeV2.

Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this Letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6.7, and 8.5 GeV2. By extending the range of Q2 for which G(E)(p) is accurately determined by more than 50%, these measurements will provide significant constraints on models of nucleon structure in the nonperturbative regime.

Absorption of the ω and ϕ mesons in nuclei.

Because of their long lifetimes, the ω and ϕ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from 2H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e+e- channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSA-TAPS experiment and cannot be explained by recent theoretical models.

Measurement of single- and double-spin asymmetries in deep inelastic pion electroproduction with a longitudinally polarized target.

We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes ϕ have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q2. A significant nonzero sin2ϕ single spin asymmetry was observed for the first time indicating strong spin-orbit correlations for transversely polarized quarks in the longitudinally polarized proton.

Measurement of the differential cross section for the reaction gamman-->pi- p from deuterium.

We report a measurement of the differential cross section for the gamman-->pi- p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (thetac.m.) between 50 degrees and 115 degrees. We confirm a previous indication of a broad enhancement around a c.m. energy ([sqrt]s) of 2.1 GeV at thetac.m.=90 degrees in the scaled differential cross section s7dsigma/dt and a rapid falloff in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for thetac.m. from 70 degrees to 105 degrees.

Improved measurement of the positive-muon lifetime and determination of the Fermi constant.

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau(micro)=2.197 013(24) micros, is in excellent agreement with the previous world average. The new world average tau(micro)=2.197 019(21) micros determines the Fermi constant G(F)=1.166 371(6)x10(-5) GeV-2 (5 ppm). Additionally, the precision measurement of the positive-muon lifetime is needed to determine the nucleon pseudoscalar coupling g(P).

Contractile response to colonic distention is influenced by oscillation frequency.

Static colonic mechanical properties are characterized by stepwise balloon distention. It is unclear whether the state of contractile activation affects frequency-dependent differences in biomechanical properties. Our aim was to investigate the frequency-dependence of colonic mechanical properties by sinusoidal oscillation. A descending colonic balloon was sinusoidally oscillated by 25 mL at 5, 10 and 20 cpm in randomized order for 20 min at each frequency in six healthy subjects before and after neostigmine. Volume oscillation was between 75-100 mL before, and 25-50 mL after neostigmine. Pressure waveforms were most variable shortly after commencing oscillation, reflecting an initial contractile response to distention. Elastance (i.e. pressure response to imposed volume) and hysteresivity were estimated; hysteresivity represents the proportion of energy added to the system during inflation, which cannot be recovered during deflation. Colonic elastance was frequency dependent, being highest and most variable at 10 cpm. In contrast, hysteresivity was not significantly different across frequencies. Neostigmine increased mean colonic elastance at all frequencies, and hysteresivity only at 5 cpm. Thus, colonic mechanical properties, particularly elastance are frequency-dependent. The frequency-dependence of colonic mechanical properties is worthy of future study because it may provide insights into reflex responses in health and disease.

Role of Cbfa1 in ameloblastin gene transcription.

Ameloblastin is a tooth-specific extracellular matrix protein that is thought to play a role in enamel crystal formation in the developing dentition. The murine ameloblastin promoter functions in a cell type-specific manner and contains cis-acting elements that function both to enhance and to suppress transcription. The objective of this study was to determine whether the transcription factor Cbfa1, known to be essential for transcription of other mineralized tissue genes, is also required for ameloblastin transcription. Site-directed mutagenesis of the Cbfa1-binding site (-248 base pairs) termed osteoblast-specific element 2 (OSE2) decreased ameloblastin promoter activity by greater than 50% in ameloblast-like cells. No differences in promoter activity were observed in two other oral tissue-derived cell lines transfected with similar constructs. Nuclear factor binding to the ameloblastin promoter was also shown to be cell type-specific and was altered by site-specific mutations in the OSE2 site. Cbfa1 was specifically shown to participate in the DNA-protein complexes between nuclear factors and the ameloblastin OSE2 site by supershift electrophoretic mobility shift assays. The findings that Cbfa1 interacts with functionally important regions of the ameloblastin promoter while promoter activity is diminished in constructs containing site-directed mutations in the Cbfa1 site indicate that Cbfa1 possesses an important function in transcription of the ameloblastin gene.

Characterization of heat-inducible expression and cloning of HtpG (Hsp90 homologue) of Porphyromonas gingivalis.

Porphyromonas gingivalis is implicated in the etiology of periodontal disease. Associations between microbial virulence and stress protein expression have been identified in other infections. For example, Hsp90 homologues in several microbial species have been shown to contribute to virulence. We previously reported that P. gingivalis possessed an Hsp90 homologue (HtpG) which cross-reacts with human Hsp90. In addition, we found that elevated levels of serum antibody to Hsp90 stress protein in individuals colonized with this microorganism were associated with periodontal health. However, the role of HtpG in P. gingivalis has not been explored. Therefore, we cloned the htpG gene and investigated the characteristics of HtpG localization and expression in P. gingivalis. htpG exists as a single gene of 2,052 bp from which a single message encoding a mature protein of approximately 68 kDa is transcribed. Western blot analysis revealed that the 68-kDa polypeptide was stress inducible and that a major band at 44 kDa and a minor band at 40 kDa were present at constitutive levels. Cellular localization studies revealed that the 44- and 40-kDa species were associated with membrane and vesicle fractions, while the 68-kDa polypeptide was localized to the cytosolic fractions.

Cloning and characterization of the murine ameloblastin promoter.

The molecular mechanisms directing the highly restricted expression pattern of murine ameloblastin were characterized by cloning and functional analysis of the ameloblastin promoter. The transcription start site, mapped by primer extension, was located 19 base pairs (bp) 5' of the published cDNA. The promoter was analyzed in a mouse ameloblast-like cell line (LS8) and was compared with promoter activity in primary gingival fibroblasts and pulp fibroblasts. Sequential 5'-deletion mutants encompassing DNA sequences from -1616 to -781 bp exhibited high promoter activity in LS8 cells, whereas the promoter activity decreased to 50% of the full-length construct in the -781- and -477-bp regions. The -217-bp promoter region regained promoter activity that approached the activity of the full-length promoter construct, suggesting that both positive and negative cis-acting regions may be involved in ameloblastin transcriptional regulation. Activity of the ameloblastin promoter in gingival and pulp fibroblasts was minimal and ranged from 8 to 30% of the activity in ameloblast-like cells. Several DNA-protein complexes were formed between functionally important promoter fragments and nuclear extracts from LS8 cells. The inactivity of promoter constructs in pulp and gingival fibroblasts as well as the absence of similar DNA-protein complexes from these cells suggest that regulatory regions of the murine ameloblastin promoter may function in a cell-specific manner.

Prevalence of stroke in rural community--an overview of Indian experience.

Various prevalence studies of stroke conducted in different regions of rural India have been analyzed and compared with prevalence study of stroke in 51,165 rural population of Haryana. The prevalence of stoke varies in different regions of country and ranges from 40 to 270/100,000 rural population. The prevalence rates correspond to that in urban areas in same region but is much lower than stroke prevalence in metropolitan cities in India and from reported prevalence of 400-800/100,000 in Western countries. Ethnic, socio-economic and dietary factors may be responsible for this variance.

Physiological and biochemical characterization of intergeneric hybrids of thermotolerant and non-thermotolerant yeasts.

Kluyveromyces-like intergeneric hybrids of thermotolerant Kluyveromyces marxianus and non-thermotolerant Saccharomyces cerevisiae, produced in a previous study by protoplasmic fusion, have been characterized. On molasses, these strains produced ethanol in excess of 6% (v/v) both at 30 and 45 degrees C as against 3% and 4.2% (v/v) by the former parent at 30 and 45 degrees C, respectively. In hybrids, the increase in ethanol production appeared to be a sequel to increased activities of alcohol dehydrogenase and pyruvate kinase, derived probably from S. cerevisiae parent. Hybrid ADH-isozyme pattern on polyacrylamide gel corroborated the presence of S. cerevisiae ADH in the tested hybrids. Regression analyses indicated a positive correlation between ethanol production and ADH or PK or both (r approximately 0.76-0.84).

Process optimization for continuous ethanol fermentation by alginate-immobilized cells of Saccharomyces cerevisiae HAU-1.

Continuous ethanol production by immobilized cells of Saccharomyces cerevisiae HAU-1 has been studied using synthetic and molasses based medium in column reactors. Immobilization of 30% yeast cells biomass (wet) in 1.5% calcium alginate gel resulted in the production of 20.8 g. l-1.h-1 alcohol at a dilution rate of 0.36 h-1 with approximately 1/3rd volume of the column reactor packed with gel beads. Optimum diameter of the beads was found to be 3.5 mm for efficient fermentation. The size of the column reactor (length to diameter ratio) also affected the productivity and fermentation efficiency due to gas hold-up and mass transfer effects. Molasses could also be fermented by this system but at a lower fermentation efficiency which could be improved, to some extent, by supplementation with nutrients.

Factors associated with awareness and knowledge of cervical cancer in a community: implication for health education programmes in developing countries.

An attempt has been made to study the correlates of knowledge of cervical cancer in a community. The survey undertaken is a part of Knowledge, Attitude and Practice (KAP) study prior to initiation of cytological screening. Total women interviewed by KAP survey were 1411 selected through 2 stage stratified random sampling. Subjects for the present analysis consisted of a group of women who had reported previous gynaecological problems related to cervical cancer. The study brought out that younger women had better awareness and knowledge about cervical cancer and related information. Literacy status for education and exposure to family planning was influential in creating awareness about cervical cancer. Lastly, the earlier episodes of gynaecological problems, and treatment seeking behaviour lead to higher awareness (efforts may be made to innovate ways to reach older and illiterate women at risk of cervical cancer for better awareness in the community.

PIP: Data were collected from a community-based cytological screening program tested by Maulana Azad Medical College (MAMC), Delhi, India, in order to utilize the health infrastructure for prevention, detection, and management of cancerous lesions of the cervix and to establish a community referral system for control of cervical cancer. The Alipur Primary Health Center field practice area of MAMC provides health care to 65,000 people in 27 villages. 609 (42.2%) of the total of 1411 women interviewed reported previous incidence of gynecological problems, but only 281 had sought treatment. 36.3% of those who reported earlier gynecological problems and 40.2% of those who sought treatment, as compared to 30.8% of all the women interviewed, were aware about cervical cancer in general. The literacy status and ever use of family planning was significantly (p .05) associated in all groups with the awareness of cervical cancer, earlier episodes of gynecological problems, and seeking treatment. Among women aged less than 35 years, who were informed about cervical cancer, there were statistically significant differences (p .5); these were 31.1% of all the women interviewed, 33.8% of those who reported earlier gynecological problems, and 43.9% of those who sought treatment for earlier gynecological problems compared to women aged 35 years and above (P 0.05). Only 114 out of 221, who were informed and who reported gynecological problems, sought treatment (acceptors). Non-acceptors of treatment in this group lacked correct knowledge about cervical cancer. 34.5% of acceptors knew about the age of onset, 11.4% about early symptoms, and 24.8% about the method of early detection compared to 30.6%, 0.0%, and 3.7% of non-acceptors, respectively. 68.5% of the non-acceptors had obtained information regarding cervical cancer from relatives, neighbors, and friends, while the acceptors had obtained the information from hospitals and mass media also. 60.2% of acceptors were exposed to family planning compared to 50.9% of non-acceptors.

Characterisation of the specific p-nitrophenylphosphatase gene and protein of Schizosaccharomyces pombe.

Cloning and sequencing of the pho2 gene which codes for a specific p-nitrophenylphosphatase from Schizosaccharomyces pombe is described. The gene has an open contiguous reading frame of 269 amino acids corresponding to a protein with a molecular mass of 29.5 kDa and a calculated pI of 6.6. The sequence reveals four regions that share significant sequence similarity with the corresponding gene PHO13 of Saccharomyces cerevisiae. Purification of the enzyme to apparent homogeneity is reported. The amino acid composition of the purified protein matches well the values predicted from the nucleotide sequence. On SDS/polyacrylamide gels, the enzyme runs as a protein with a molecular mass of 33 kDa, and by Sephadex chromatography under nondenaturing conditions as 70 kDa. This indicates that the enzyme is a homodimer in its native form. The enzyme is not glycosylated. Its activity is stimulated by Mg2+ and inhibited by Zn2+. The available data on p-nitrophenylphosphatase do not give any clues to its biological role and its physiological substrates.

Allele-specific complementation of an Escherichia coli leuB mutation by a Lactobacillus bulgaricus tRNA gene.

A Lactobacillus bulgaricus gene encoding a serine tRNA with the anticodon CGA was isolated from a L. bulgaricus clone bank and characterized. This gene is expressed and active in Escherichia coli. The wild-type form of the gene allele specifically complements the E. coli leuB6 mutation. This process depends on gene copy number; high copy number restores leucine prototrophy, while low copy number does not. We suggest that restoration of activity of the mutant leuB6 allele occurs by missense suppression. The L. bulgaricus tRNA(CGASer) when overproduced in E. coli is misacylated at a low frequency, leading to the insertion of an amino acid other than serine in response to the presumed mutant codon UCG in the leuB6 gene. Nucleotide (nt) sequences flanking the tRNA coding region are present in the L. bulgaricus tRNA gene, closely resembling E. coli promoter and terminator elements. A noteworthy feature of this tRNA gene is the extreme length (22 nt) of its extra arm. The 3'-terminal CCA of the tRNA is not encoded in this tRNA gene and thus must be added posttranscriptionally.

Oral zinc sulphate therapy in acne vulgaris: a double-blind trial.

The effect of zinc sulphate and placebo was compared in a double-blind trial in 56 patients suffering from acne vulgaris. Serum vitamin A levels were studied in all, before and at the end of therapy, 29 patients received zinc sulphate 600 mg daily and 27 patients received placebo. Patients on placebo showed no improvement. After 12 weeks of treatment with zinc sulphate, 17 patients (58%) showed significant improvement. There was a statistically significant decrease in the number of papules, infiltrates and cysts. In zinc-treated cases there was statistically significant increase in serum vitamin A levels, while no change was found in the placebo group.