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.

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).

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 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.

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.

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.

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.

Extractive separation and spectrophotometric determination of tungsten as ferrocyanide.

Tungsten, in amounts ranging from micrograms to milligrams, can be extracted into isoamyl alcohol, as the tungsten(V) ferrocyanide complex obtained by reduction of tungsten(VI) with tin(II) in 4M hydrochloric acid containing ferrocyanide. It can thus be separated from iron, cobalt, chromium, manganese, arsenic, antimony, bismuth, silicon, calcium and copper, their precipitation being prevented by addition of glycerol and, in the case of iron, sulphosalicyclic acid. Molybdenum, vanadium and nickel are not separated from tungsten, however. Tungsten can also be determined spectrophotometrically as tungsten(V) ferrocyanide. The absorbance of the brown complex is measured in aqueous solution or preferably after extraction into isoamyl alcohol. As many alloying elements interfere, they should be separated by the ferrocyanide extraction or other suitable method. Both the separation and the determination methods give satisfactory results with an overall error of not more than 0.5% in the analysis of practical samples containing low or high percentages of tungsten.

Determination of tungsten with iron(III) after reduction with mercury in thiocyanate medium.

Tungsten(V) is formed by shaking for 2 min sodium tungstate solution in 0.4 M potassium thiocyanate-4M hydrochloric acid medium, with mercury. It is titrated with standard iron(III) solution. The thiocyanate present stabilizes W(V) to aerial oxidation and also acts as indicator. The W(V) can also be titrated potentiometrically in 7M hydrochloric acid, a tungsten wire electrode being used. Fe, Ni, Cr, Zr, Bi, Sb, Ce, Al, Pb, Ca and U do not interfere. Cu, V and As can be tolerated up to 5 mg. Co, Mo, Re, Nb and Mn interfere, but not in the potentiometric determination. The method is direct, simple, rapid, accurate and reproducible.

Gravimetric determination of tungsten with tetraphenylarsonium chloride after its extraction as thiocyanate.

Small amounts of tungsten in natural and industrial samples can be freed from all important interfering elements by extraction of molybdenum by xanthate, reduction of tungsten by mercury and extraction of tungsten(V) thiocyanate into tribenzylamine, and finally back-extraction. The tungsten can be then determined as tetraphenylarsonium tungstate by precipitating it at pH 2-4, filtering it off and drying it at 110 degrees for 45 min. An overall error of 0.1-0.2% is obtained for 5-60 mg of tungsten.

Spectrophotometric determination of tungsten with thiocyanate.

The yellow W(V) thiocyanate complex is formed by shaking sodium tungstate solution in 0.2-0.8M potassium thiocyanate and 4-5M hydrochloric acid, with mercury. It is extracted with 2% tribenzylamine solution in chloroform and measured at 410 nm. U, Ti, V, Cr, Fe, Co, Ni, Mn, Al, Pb, Sn, Bi, Pd, Sb and Cu do not interfere. Pt and Mo in amount equal to that of tungsten give errors of up to 0.4 and 2% respectively. The sensitivity is 0.013 mug ml and Beer's law is obeyed up to 24 mug ml .

Extractive separation of Tungsten as phosphotungstate.

Tungsten can be extracted quantitatively as phosphotungstate in micro as well as milligram concentrations by extraction with MIBK from 0.1-1M hydrochloric acid if the w/w tungsten:phosphorus ratio = 7, and separated from Fe, Ni, Co, Cr, Mn, Cu, Ca, U, Th, As, Sb, Bi and Si, after reduction of Fe(III) and cr(VI) with thiosulphate, in natural and industrial samples. Mo and V suppress the extraction of tungsten and therefore require prior separation. The method takes 15 min for a single separation and gives highly satisfactory results with an overall error of about 0.1-0.2% over the range 10-100 mg tungsten in the sample.

Extractive separation and spectrophotometric determination of tungsten as phosphotungsten blue.

Phosphotungsten blue is produced by tin(II) reduction of tungstate solution complexed with phosphate at a w/w ratio of W/P = 5, in 4M hydrochloric acid medium, and extracted with isoamyl alcohol; thus tungsten is separated from Fe(III), Ni, Co, Cr(III), V(V), As(V), Sb(III), Bi, Si, U(VI), Ca and Cu(II). In presence of bismuth (0.5 mg/ml), 99.7% W is separated in a single extraction. After alkaline back-extraction, tungsten is determined spectrophotometrically as phosphotungsten blue; it is measured at 930 nm in aqueous solution or at 900-960 nm after isoamyl alcohol extraction, the Beer's law ranges being 0.08-0.6 and 0.16-0.72 mg/ml respectively. The methods are shown to give satisfactory results in the analysis of practical samples containing some milligrams of tungsten.

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.

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.

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.