Determination of the

We report the first measurement of the parity-violating elastic electron scattering asymmetry on ^{27}Al. The ^{27}Al elastic asymmetry is A_{PV}=2.16±0.11(stat)±0.16(syst) ppm, and was measured at ⟨Q^{2}⟩=0.02357±0.00010 GeV^{2}, ⟨θ_{lab}⟩=7.61°±0.02°, and ⟨E_{lab}⟩=1.157 GeV with the Q_{weak} apparatus at Jefferson Lab. Predictions using a simple Born approximation as well as more sophisticated distorted-wave calculations are in good agreement with this result. From this asymmetry the ^{27}Al neutron radius R_{n}=2.89±0.12 fm was determined using a many-models correlation technique. The corresponding neutron skin thickness R_{n}-R_{p}=-0.04±0.12 fm is small, as expected for a light nucleus with a neutron excess of only 1. This result thus serves as a successful benchmark for electroweak determinations of neutron radii on heavier nuclei. A tree-level approach was used to extract the ^{27}Al weak radius R_{w}=3.00±0.15 fm, and the weak skin thickness R_{wk}-R_{ch}=-0.04±0.15 fm. The weak form factor at this Q^{2} is F_{wk}=0.39±0.04.

Precision Measurement of the Beam-Normal Single-Spin Asymmetry in Forward-Angle Elastic Electron-Proton Scattering.

A beam-normal single-spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable related to the imaginary part of the two-photon exchange process. We report a 2% precision measurement of the beam-normal single-spin asymmetry in elastic electron-proton scattering with a mean scattering angle of θ_{lab}=7.9° and a mean energy of 1.149 GeV. The asymmetry result is B_{n}=-5.194±0.067(stat)±0.082 (syst) ppm. This is the most precise measurement of this quantity available to date and therefore provides a stringent test of two-photon exchange models at far-forward scattering angles (θ_{lab}→0) where they should be most reliable.

Observation of the (Λ)(7)He hypernucleus by the (e, e'K+) reaction.

An experiment with a newly developed high-resolution kaon spectrometer and a scattered electron spectrometer with a novel configuration was performed in Hall C at Jefferson Lab. The ground state of a neutron-rich hypernucleus, (Λ)(7)He, was observed for the first time with the (e, e'K+) reaction with an energy resolution of ~0.6 MeV. This resolution is the best reported to date for hypernuclear reaction spectroscopy. The (Λ)(7)He binding energy supplies the last missing information of the A = 7, T = 1 hypernuclear isotriplet, providing a new input for the charge symmetry breaking effect of the ΛN potential.

First determination of the weak charge of the proton.

The Q(weak) experiment has measured the parity-violating asymmetry in ep elastic scattering at Q(2)=0.025(GeV/c)(2), employing 145 µA of 89% longitudinally polarized electrons on a 34.4 cm long liquid hydrogen target at Jefferson Lab. The results of the experiment's commissioning run, constituting approximately 4% of the data collected in the experiment, are reported here. From these initial results, the measured asymmetry is A(ep)=-279±35 (stat) ± 31 (syst) ppb, which is the smallest and most precise asymmetry ever measured in ep scattering. The small Q(2) of this experiment has made possible the first determination of the weak charge of the proton Q(W)(p) by incorporating earlier parity-violating electron scattering (PVES) data at higher Q(2) to constrain hadronic corrections. The value of Q(W)(p) obtained in this way is Q(W)(p)(PVES)=0.064±0.012, which is in good agreement with the standard model prediction of Q(W)(p)(SM)=0.0710±0.0007. When this result is further combined with the Cs atomic parity violation (APV) measurement, significant constraints on the weak charges of the up and down quarks can also be extracted. That PVES+APV analysis reveals the neutron's weak charge to be Q(W)(n)(PVES+APV)=-0.975±0.010.

Probing quark-gluon interactions with transverse polarized scattering.

We have extracted QCD matrix elements from our data on doubly polarized inelastic scattering of electrons on nuclei. We find the higher twist matrix element d˜2, which arises strictly from quark-gluon interactions, to be unambiguously nonzero. The data also reveal an isospin dependence of higher twist effects if we assume that the Burkhardt-Cottingham sum rule is valid. The fundamental Bjorken sum rule obtained from the a0 matrix element is satisfied at our low momentum transfer.

Latin American Dialysis and Renal Transplant Registry: 2008 report (data 2006).

INTRODUCTION: Between 1991 and 2006, the Latin American Dialysis and Renal Transplantation Registry collected data from 20 countries (Argentina, Brazil, Bolivia, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Dominican Republic, Venezuela and Uruguay). Access to RRT was universal in Argentina, Brazil, Chile, Cuba, Puerto Rico, Venezuela and Uruguay, all countries belonging to the medium-high or high income group. METHODS: Data about patients on renal replacement therapy (RRT) were supplied by national affiliates or the Registry's Coordination Committee. Transplant data were gathered and shared with the Latin American and Caribbean Society of Transplantation. RESULTS: RRT prevalence increased from 162 patients per million population (pmp) in 1991 to 478 pmp in 2005 and 473 pmp in 2006 (59.2% hemodialysis, 20.4% peritoneal dialysis and 20.4% with a functioning kidney allograft). Countries with the highest prevalence were Puerto Rico (1,148.9 pmp), Uruguay (924.5 pmp) and Chile (907.6 pmp). Latin America's (LA) incidence increased from 27.8 pmp in 1992 to 188 pmp in 2006. The LA Kidney transplant rate increased from 3.7 pmp in 1987 to 15,4 pmp in 2006, and 166 combined transplants - kidney and another organ, mainly pancreas - were performed. In the medium-high income group 2006, (Argentina, Brazil, Chile, Costa Rica, Cuba, Mexico, Panama, Uruguay, Venezuela) the prevalence rate was 534.8 pmp vs. 289.5 pmp in the middle-low income group. The transplant rate was 18.4 pmp in the medium-high income group vs. 7 pmp in the middle-low group (p < 0.01). CONCLUSIONS: RRT incidence and prevalence continue to grow steadily. Access to RRT is universal only in some countries included in the medium-high or high income group. It is imperative to accomplish the goal of making RRT available to all who need it.

Measurement of Parity Violation in np Capture: the NPDGamma Experiment.

The NPDGamma experiment will measure the parity-violating directional gamma ray asymmetry A γ in the reaction [Formula: see text]. Ultimately, this will constitute the first measurement in the neutron-proton system that is sensitive enough to challenge modern theories of nuclear parity violation, providing a theoretically clean determination of the weak pion-nucleon coupling. A new beam-line at the Los Alamos Neutron Science Center (LANSCE) delivers pulsed cold neutrons to the apparatus, where they are polarized by transmission through a large volume polarized (3)He spin filter and captured in a liquid para-hydrogen target. The 2.2 MeV gamma rays from the capture reaction are detected in an array of CsI(Tl) scintillators read out by vacuum photodiodes operated in current mode. We will complete commissioning of the apparatus and carry out a first measurement at LANSCE in 2004-05, which would provide a statistics-limited result for A γ accurate to a standard uncertainty of ±5 × 10(-8) level or better, improving on existing measurements in the neutron-proton system by a factor of 4. Plans to move the experiment to a reactor facility, where the greater flux would enable us to make a measurement with a standard uncertainty of ±1 × 10(-8), are actively being pursued for the longer term.

Commissioning of the NPDGamma Detector Array: Counting Statistics in Current Mode Operation and Parity Violation in the Capture of Cold Neutrons on B 4 C and (27) Al.

The NPDGamma γ-ray detector has been built to measure, with high accuracy, the size of the small parity-violating asymmetry in the angular distribution of gamma rays from the capture of polarized cold neutrons by protons. The high cold neutron flux at the Los Alamos Neutron Scattering Center (LANSCE) spallation neutron source and control of systematic errors require the use of current mode detection with vacuum photodiodes and low-noise solid-state preamplifiers. We show that the detector array operates at counting statistics and that the asymmetries due to B4C and (27)Al are zero to with- in 2 × 10(-6) and 7 × 10(-7), respectively. Boron and aluminum are used throughout the experiment. The results presented here are preliminary.

Bone disease in patients with long-term renal transplantation and normal renal function.

Renal osteodystrophy may persist during the early years after renal transplantation. However, information on bone status after a successful long-term renal transplantation is limited. We examined biochemical parameters, bone mineral density (BMD), and bone histomorphometry in 25 asymptomatic men with normal renal function after 7.5 +/- 5.7 years of a renal transplantation. Serum calcium, phosphorus, alkaline phosphatase, and 1,25(OH)(2)D(3) levels and urinary calcium level and cyclic andenosine monophosphate excretion were within normal range in all patients. Serum intact parathyroid hormone (PTH) level was elevated in 11 subjects (133.6 +/- 78 pg/mL) and normal in the other 14 subjects (47.9 +/- 13.6 pg/mL). Mean BMD at the lumbar spine and femoral neck was low in the entire group. However, it progressively increased as time after transplantation increased, approaching normal values after 10 years. Bone histomorphometric analysis showed bone resorption, osteoid volume, and osteoid surface greater than normal range in the majority of patients. Bone formation rate and mineralization surface were low, and mineralization time was delayed in most patients. These lesions were more severe in patients after 3 to 4 years of transplantation but improved with time and approached normal values after a period of 10 years. PTH values did not correlate with bone histological characteristics or BMD. These results show that the bone alterations observed after long-term renal transplantation consist of a mixed bone disease in which features of high bone turnover coexist with altered bone formation and delayed mineralization. These findings may result from the combined effect of preexisting bone disease and immunosuppressive therapy.

Measurement of tensor polarization in elastic electron-deuteron scattering at large momentum transfer

Tensor polarization observables ( t(20), t(21), and t(22)) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)(2). The experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors G(C) and G(Q). They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.

Intravenous erythropoietin (rHuEPO) administration increases plasma endothelin and blood pressure in hemodialysis patients.

The correction of anemia in end stage renal disease with recombinant human erythropoietin (rHuEPO) is associated with hypertension in about a third of hemodialysis patients. In the present study, we investigated the role of endothelin (ET-1) on rHuEPO associated hypertension and the effect of the rHuEPO administration route on plasma ET-1 levels. We studied 50 stable chronic hemodialysis patients who were divided into three groups: 26 patients received rHuEPO intravenously (IV) and 21 subcutaneously (SC). The control group was nine patients who were treated with nandrolone decanoate (ND). Prehemodialysis ET-1 plasma levels were correlated with mean arterial pressure (MAP), hematocrit (Hct), time on dialysis, and rHuEPO doses. The antihypertensive therapeutic index (ATI) was used to determine the changes in blood pressure medication intake. We observed that the ET-1 levels were significantly higher in the IV group (19.3 +/- 2) than the SC (5.0 +/- 0.6) or ND groups (3.6 +/- 0.4 pg/mL) (P < 0.001, IV v SC or ND). After IV rHuEPO treatment, there were increases in both MAP (pre- v post-rHuEPO, P < .001) and in ATI (pre- v post-rHuEPO, P < .001). In the SC group, the increases in MAP and ATI were not significant. Only the IV group showed a significant correlation between MAP and ET-1 levels (r = .05, P = .02). To accomplish the same Hct, the IV group received higher rHuEPO doses than those of the SC (180 +/- 15 v 87 +/- 12 U/kg/week) (P < .001). No significant correlations were found between the plasma ET-1 levels and Hct, time on dialysis and rHuEPO doses.(ABSTRACT TRUNCATED AT 250 WORDS)

[Role of bones in the physiopathology of idiopathic hypercalciuria: effect of amino-bisphosphonate alendronate]. / Papel del hueso en la fisiopatología de la hipercalciuria idiopática. Efecto del aminobisfosfonato alendronato.

Previous studies from our laboratory demonstrated that bone mineral content is affected in patients with idiopathic hypercalciuria and that there is a correlation between bone mineral loss and in-vitro cytokine production. At the same time we found that short term treatment with alendronate decreased urinary calcium in these subjects. In the present study we have examined the long-term effects of alendronate treatment (10 mg/day for one year) on urinary calcium, urinary hydroxyproline and bone mineral content in 18 idiopathic hypercalciuric and 8 normocalciuric stone formers. Clinical characteristics, as well as gender and age distribution were similar in both groups. Urinary calcium and hydroxyproline, were measured monthly. Calcium excretion decreased significantly at the end of the first month, and remained lower thereafter (277 +/- 28, before vs. 202 +/- 26 mg/g creatinine, after 12 months on alendronate, p < 0.01). Urinary hydroxyproline decreased significantly during the study (125.5 +/- 32.1 vs. 39.66 +/- 17.5 mg/g creatinine, p < 0.05). Serum calcium, glomerular filtration rate, and urinary sodium, did not change during the study. Lumbar spine bone density (trabecular bone) obtained with X ray absorptiometry revealed a significant increase from 1.162 +/- 0.231 to 1.197 +/- 0.248 g/cm2 (p < 0.01). These changes were associated with a significant decrease in IL-1 alpha mRNA transcription by unstimulated and lipopolysaccharide stimulated blood mononuclear cells, as tested by the reverse transcriptase polymerase chain reaction. No changes were observed in bone cortical sites (femoral neck). Normocalciuric subjects showed no significant changes in urinary calcium. In summary, the changes observed in urinary calcium excretion and different bone metabolic parameters, suggest a role of bone in the pathophysiology of idiopathic hypercalciuria.

[Initial evaluation of aluminum concentrations in patients with nephropathy and undergoing hemodialysis at the Miguel Pérez Carreño Hospital and the University Hospital of Caracas (Venezuela)]. / Evaluación inicial de las concentraciones de aluminio en pacientes con nefropatía y sometidos a hemodiálisis en los Hospitales Miguel Pérez Carreño y Universitario de Caracas (Venezuela).

The present work reports the concentrations of aluminum in whole blood and dialysis solutions of 27 patients with chronic renal failure and under hemodialysis treatment at Miguel Pérez Carreño and University Hospitals, both from Caracas city. Aluminum levels of the water used to prepare the dialysates were also monitored and the metal mobilization during dialysis studied. Patients' mean blood aluminum concentrations (ca. 34 micrograms AI/L) were lower than those of renal individuals from Maracaibo (ca. 58 micrograms AI/L), situation related to the low metal contents of the dialysate water (ca. 14 micrograms AI/L). In addition, Caracas drinking water showed up very high aluminum concentrations, above 475 micrograms/L. There was a relationship between the renal patients' blood aluminum concentrations and (1) the metal contents of the dialysis solutions and (2) the ingestion of aluminum hydroxide-based antacids. Aluminum transfer incorporation processes toward the patients' blood were observed in both dialysis units. This was due to the favorable concentration gradients (blood aluminum concentration/dialysate aluminum concentration) established at the start of every hemodialysis treatment.

Testing the standard model by precision measurement of the weak charges of quarks.

In a global analysis of the latest parity-violating electron scattering measurements on nuclear targets, we demonstrate a significant improvement in the experimental knowledge of the weak neutral-current lepton-quark interactions at low energy. The precision of this new result, combined with earlier atomic parity-violation measurements, places tight constraints on the size of possible contributions from physics beyond the standard model. Consequently, this result improves the lower-bound on the scale of relevant new physics to approximately 1 TeV.

Proton spin structure in the resonance region.

We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV

Transverse beam spin asymmetries in forward-angle elastic electron-proton scattering.

We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q2=0.15, 0.25 (GeV/c)2. The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A(n) provides a direct probe of the imaginary component of the 2gamma exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments.

Extracting nucleon strange and anapole form factors from world data.

The complete world set of parity-violating electron scattering data up to Q2 approximately 0.3 GeV2 is analyzed. We extract the current experimental determination of the strange electric and magnetic form factors of the proton, as well as the weak axial form factors of the proton and neutron, at Q2=0.1 GeV2. Within experimental uncertainties, we find that the strange form factors are consistent with zero, as are the anapole contributions to the axial form factors. Nevertheless, the correlation between the strange and anapole contributions suggest that there is only a small probability that these form factors all vanish simultaneously.

Strange-quark contributions to parity-violating asymmetries in the forward g0 electron-proton scattering experiment.

We have measured parity-violating asymmetries in elastic electron-proton scattering over the range of momentum transfers 0.12 < or =Q2 < or =1.0 GeV2. These asymmetries, arising from interference of the electromagnetic and neutral weak interactions, are sensitive to strange-quark contributions to the currents of the proton. The measurements were made at Jefferson Laboratory using a toroidal spectrometer to detect the recoiling protons from a liquid hydrogen target. The results indicate nonzero, Q2 dependent, strange-quark contributions and provide new information beyond that obtained in previous experiments.