Measurement of the Vector and Tensor Asymmetries at Large Missing Momentum in Quasielastic (e[over →],e

We report the measurement of the beam-vector and tensor asymmetries A_{ed}^{V} and A_{d}^{T} in quasielastic (e[over →],e^{'}p) electrodisintegration of the deuteron at the MIT-Bates Linear Accelerator Center up to missing momentum of 500 MeV/c. Data were collected simultaneously over a momentum transfer range 0.1

Precise measurement of deuteron tensor analyzing powers with BLAST.

We report a precision measurement of the deuteron tensor analyzing powers T(20) and T(21) at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range Q=2.15-4.50 fm(-1) with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors G(C) and G(Q) were separated with improved precision, and the location of the first node of G(C) was confirmed at Q=4.19±0.05 fm(-1). The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of T(20) and the first node of G(C).

Charge form factor of the neutron at low momentum transfer from the 2H-->(e-->,e'n)1H reaction.

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio GEn/GMn was extracted from the beam-target vector asymmetry AedV at four-momentum transfers Q2=0.14, 0.20, 0.29, and 0.42 (GeV/c)2.

Measurement of the absolute n p scattering differential cross section at 194 MeV.

We describe a double-scattering experiment with a novel tagged neutron beam to measure differential cross sections for np backscattering to better than +/-2% absolute precision. The measurement focuses on angles and energies where the cross section magnitude and angle dependence constrain the charged pion-nucleon coupling constant, but existing data show serious discrepancies among themselves and with energy-dependent partial-wave analyses. The present results are in good accord with the partial-wave analyses, but deviate systematically from other recent measurements.

Observation of the charge symmetry breaking d+d-->4He+pi(0) reaction near threshold.

We report the first observation of the charge symmetry breaking d+d-->4He+pi(0) reaction near threshold. Measurements using a magnetic channel (gated by two photons) of the 4He scattering angle and momentum (from time of flight) permitted reconstruction of the pi(0) "missing mass," the quantity used to separate 4He+pi(0) events from the continuum of double radiative capture 4He+gamma+gamma events. We measured total cross sections for neutral pion production of 12.7+/-2.2 pb at 228.5 MeV and 15.1+/-3.1 pb at 231.8 MeV. The uncertainty is dominated by statistical errors. These cross sections arise fundamentally from the down-up quark mass difference and quark electromagnetic effects that contribute in part through meson mixing (e.g., pi(0)-eta) mechanisms.

Measurement of gamow-teller strength for 176Yb --> 176Lu and the efficiency of a solar neutrino detector

We report a 0 degrees 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine Gamow-Teller (GT) matrix elements relative to the model independent Fermi matrix element. The data show that there is an isolated concentration of GT strength in the low-lying 1(+) states making the proposed Low Energy Neutrino Spectroscopy detector (based on neutrino captures on 176Yb) sensitive to pp and 7Be neutrinos and a promising detector to resolve the solar neutrino problem.

Selective speech perception alterations in schizophrenic patients reporting hallucinated "voices".

OBJECTIVE: The authors tested a model of hallucinated "voices" based on a neural network computer simulation of disordered speech perception. METHOD: Twenty-four patients with schizophrenia spectrum disorders who reported hallucinated voices were compared with 21 patients with schizophrenia spectrum disorders who did not report voices and 26 normal subjects. Narrative speech perception was assessed through use of a masked speech tracking task with three levels of superimposed phonetic noise. A sentence repetition task was used to assess grammar-dependent verbal working memory, and an auditory continuous performance task was used to assess nonlanguage attention. RESULTS: Masked speech tracking task and sentence repetition performance by hallucinating patients was impaired relative to both nonhallucinating patients and normal subjects. Although both hallucinating and nonhallucinating patients demonstrated auditory attention impairments when compared to normal subjects, the two patient groups did not differ with respect to these variables. CONCLUSIONS: Results support the hypothesis that hallucinated voices in schizophrenia arise from disrupted speech perception and verbal working memory systems rather than from nonlanguage cognitive or attentional deficits.

Hypermethylation in the retinoblastoma gene is associated with unilateral, sporadic retinoblastoma.

We previously reported 9 unilateral, sporadic retinoblastomas with hypermethylation in the 5' region of the RB gene, and we found that CpG methylation in the RB promoter inhibits the binding of the retinoblastoma binding factor 1 (RBF-1) and the activating transcription factor (ATF)-like factors, thereby resulting in a considerable reduction in RB promoter activity. In this study, we screened for hypermethylation in 121 additional cases of retinoblastoma, and found 5 tumors with hypermethylation, including 4 unilateral, sporadic tumors, and one hereditary tumor. The hereditary tumor had a germline deletion of one allele, and the hypermethylation was an acquired, epigenetic change in the other allele. Another tumor had hypermethylation restricted to approximately 800 base pairs in the RB promoter region including the essential RBF-1 and ATF sites. The frequency of hypermethylation in unilateral, sporadic tumors was 9.3% combining our previous and present examinations (13 among 140), whereas the frequency was 1.0% in bilateral hereditary tumors (one among 101). The statistical analyses using the chi-square test indicated significant correlation between hypermethylation and unilateral, sporadic tumors (p < 0.05). These results suggest that hypermethylation in the RB gene is always an acquired, epigenetic change and causes about 9% of unilateral, sporadic tumors.

Quantification of the paternal allele bias for new germline mutations in the retinoblastoma gene.

New germline mutations in the human retinoblastoma gene are known to arise preferentially on paternally derived chromosomes, but the magnitude of that bias has not been measured. We evaluated 49 cases with a new germline mutation and found that in 40 cases (82%) the mutation arose on the paternally derived allele. We also evaluated 48 cases likely to have a somatic initial mutation; in this group the initial mutation arose on paternal or maternal chromosomes with approximately equal frequency. There was no statistically significant difference in the average age of fathers of children with new paternal germline mutations from the average age of fathers of children with new maternal germline mutations or somatic initial mutations. Combining the data with that from previous reports from other groups, the proportion of new germline mutations arising on a paternally derived allele is 85% (based on 72 cases; 95% confidence interval = 76-93%). This number can be useful in the genetic counseling of some families with retinoblastoma.

A neural network simulation of hallucinated "voices" and associated speech perception impairments in schizophrenic patients.

The mechanism of hallucinated speech, a symptom commonly reported by schizophrenic patients, is unknown. The hypothesis that these hallucinations arise from pathologically altered working memory underlying speech perception was explored. A neural network computer simulation of contextually guided sequential word detection based on Elman (1990a,b) was studied. Pruning anatomic connections or reducing neuronal activation in working memory caused word "percepts" to emerge spontaneously (i.e., in the absence of external "speech inputs"), thereby providing a model of hallucinated speech. These simulations also demonstrated distinct patterns of word detection impairments when inputs were accompanied by varying levels of noise. In a parallel human study, the ability to shadow noisecontaminated, connected speech was assessed. Schizophrenic patients reporting hallucinated speech demonstrated a pattern of speech perception impairments similar to a simulated neural network with reduced anatomic connectivity and enhanced neuronal activation. Schizophrenic patients not reporting this symptom did not demonstrate these speech perception impairments. Neural network simulations and human empirical data, when considered together, suggested that the primary cause of hallucinated "voices" in schizophrenia is reduced neuroanatomic connectivity in verbal working memory.

The present state of people who survived the holocaust as children.

A total of 103 Holocaust survivors who suffered from Nazi persecution during their childhood years were interviewed in 1992. The interviews were conducted using a questionnaire specially prepared for statistical studies of Holocaust survivors. The study demonstrated that most survivors in this sample still suffer today, more than 50 years after the outbreak of the Second World War, from symptoms of the survivor syndrome. Their mental suffering is in positive correlation to the intensity of the trauma they suffered in their childhood. Those who were in death camps suffer more than those who suffered during their childhood from other forms of persecution by the Nazis. The coping and adjustment of child survivors of death camps were also less successful than the coping and adjustment of child survivors who went through other forms of persecution.

[Variability of measured energy expenditure in patients with acute pancreatitis: is it possible to obtain a reliable pathology factor for these cases?]. / Variabilidad del gasto calórico medido en pacientes con pancreatitis aguda: es posible obtener un factor de patologia confiable para estos casos?

Energy expenditure was measured in 55 patients with acute pancreatitis, during variable periods ranging from 1 to 5 weeks and it was compared with estimated energy expenditure according to Harris Benedict equations. Patients with severe pancreatitis had similar measured and measured/estimated energy expenditure rations, compared to those with mild pancreatitis (1678 +/- 349.6 kcal/day and 1.1 +/- 0.19 vs 1632 +/- 383 kcal/day and 1.06 +/- 0.19). There was a high dispersion of measured/estimated rations (0.67 - 1.7) that precluded the calculation of a reliable energy expenditure correction factor for this disease. It is concluded that energy expenditure must be measured and not estimated, when planning an adequate nutritional support in patients with acute pancreatitis.