Sensitivity to discontinuous dependencies in language learners: evidence for limitations in processing space

Five experiments using the Headturn Preference Procedure examined 15- and 18-month-old children's sensitivity to morphosyntactic dependencies in English. In each experiment, the children were exposed to two types of passages. Passages in the experimental condition contained a well-formed English dependency between the auxiliary verb is and a main verb with the ending -ing. Passages in the control condition contained an ungrammatical combination of the modal auxiliary can and a main verb with the ending -ing. In the experiments, the distance between the dependent morphemes was systematically varied by inserting an adverbial of a specified length between the auxiliary and main verbs. The results indicated that 18-month-olds are sensitive to the basic relationship between is and -ing, but that 15-month-olds are not. The 18-month-olds, but not the 15-month-olds, listened significantly longer to the passages with the well-formed English dependency. In addition, the 18-month-olds showed this preference for the well-formed dependency only over a limited domain of 1-3 syllables. Over domains of 4-5 syllables, they showed no significant preference for the experimental over the control passages. These findings indicate that 18-month-olds can track relationships between functor morphemes. Additionally, these findings are consistent with the hypothesis that 18-month-olds are working with a limited processing window, and that they are only picking up relevant dependencies that fall within this window.     

The effect of abdominal wall morphology on ultrasonic pulse distortion. Part II. Simulations

Wavefront propagation through the abdominal wall was simulated using a finite-difference time-domain implementation of the linearized wave propagation equations for a lossless, inhomogeneous, two-dimensional fluid as well as a simplified straight-ray model for a two-dimensional absorbing medium. Scanned images of six human abdominal wall cross sections provided the data for the propagation media in the simulations. The images were mapped into regions of fat, muscle, and connective tissue, each of which was assigned uniform sound speed, density, and absorption values. Propagation was simulated through each whole specimen as well as through each fat layer and muscle layer individually. Wavefronts computed by the finite-difference method contained arrival time, energy level, and wave shape distortion similar to that in measurements. Straight-ray simulations produced arrival time fluctuations similar to measurements but produced much smaller energy level fluctuations. These simulations confirm that both fat and muscle produce significant wavefront distortion and that distortion produced by fat sections differs from that produced by muscle sections. Spatial correlation of distortion with tissue composition suggests that most major arrival time fluctuations are caused by propagation through large-scale inhomogeneities such as fatty regions within muscle layers, while most amplitude and waveform variations are the result of scattering from smaller inhomogeneities such as septa within the subcutaneous fat. Additional finite-difference simulations performed using uniform-layer models of the abdominal wall indicate that wavefront distortion is primarily caused by tissue structures and inhomogeneities rather than by refraction at layer interfaces or by variations in layer thicknesses.     

Preventing disability from work-related low-back pain. New evidence gives new hope--if we can just get all the players onside

Tumor necrosis factor (TNF) is a proinflammatory cytokine playing a central role in the expression of endothelial adhesion molecules required for the recruitment of inflammatory cells. Proliferative glomerulonephritis induced by anti-glomerular basement membrane (GBM) antibody is characterized by the recruitment of inflammatory cells in the glomerulus followed by capillary damage and crescent formation. The glomerular pathology may be due to a large extent to TNF induction. We therefore tested this hypothesis in TNF-deficient mice. Anti-GBM antibody administration in sensitized wild-type mice resulted in deposition of immune complexes, followed by increased intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression, as well as the influx of polymorphonuclear neutrophils (PMNs), lymphocytes, and macrophages. Distinct proteinuria preceded proliferative glomerulonephritis characterized by crescent formation. In the absence of TNF, the development of proteinuria was delayed and the formation of crescents was almost completely prevented. Although the deposition of immune complexes in glomeruli was comparable in both groups, the up-regulation of ICAM-1 and VCAM-1, as well as the influx of PMNs and lymphocytes, but not of monocytes, was dramatically reduced in TNF-deficient mice. Therefore, we conclude that TNF plays a key role in the recruitment of inflammatory cells and in the subsequent development of proliferative glomerulonephritis.     

Stress in medical students

The object of this study was to examine the main stressors experienced by students in an Irish medical school and their effects on the attitude of the students towards their training. It also determined the students' knowledge of how they could receive help and their attitudes towards seeking such help. Data was collected by an anonymous self-report questionnaire distributed to a fifth year medical school class in the Hilary Term of the academic year. These 63 students had chosen medicine as a career mainly because of vocational and academic factors and almost two thirds of them had always wanted to do medicine. However four were no longer happy with that choice. Fifty-four percent of them had felt like making a complaint on at least one occasion, but did not do so. The perceived problems were mainly verbal in nature. 41% said that this had affected their attendance. The main source of perceived mistreatment was consultant staff. Rates of perceived racial and sexual discrimination were low. Other stressors included examinations, financial issues and family issues. 52% of students did not know the process by which they could make a complaint and 30% felt that seeking help or advice from staff would be damaging to their future career. This study analyses these issues and suggests ways of addressing them.     

Correlation of the suppressive activity of a biological response modifier on the proliferation of peripheral blood mononuclear cells and the reduction of HIV titer

Activation of CD4+ cells is a prerequisite for infection by the human immunodeficiency virus (HIV). Thus, any agent capable of suppressing CD4+ cell proliferation could create a refractory stage that would impede viral infection. We have reported, in a previous publication, that a biological response modifier (BRM), polyantigenic immunomodulator (PAI) substantially reduces HIV-1 titer (from 20 to 100%) in peripheral mononuclear cells (PBMC) cultures with high viral titer (p24 = 10(2)-10(5) pg/ml). We are presenting data suggesting that the reported reduction in virus titer seems to be associated with a suppressive activity of PAI on the proliferation of PBMC from intravenous drug users (IVDU) infected and non-infected with HIV-1. PAI, a well characterized BRM, is a mixture of inactivated bacterial and influenza virus vaccines. PBMC from healthy donors and IVDU individuals were exposed to PAI, phytohemagglutinin (PHA), interleukin-2 (IL-2) and to combinations of PAI with either PHA or IL-2. Appropriate controls were included. 3H-thymidine pulsing was used as indicator of cell proliferation. The stimulation index and the difference between mean cpm of test sample and control were used to measure proliferative activity. There was a low proliferative response in the PBMC cultures from IVDU and HIV-1 positive patients, but it was substantially lower in the later group. When PBMC cultures from the same group of individuals were exposed to PAI, PHA and IL-2, and to the combination of either PAI plus PHA or IL-2, the response observed in the PAI treated group was uniformly lower than in the other treated cultures. Moreover, when PAI was combined with PHA, it exerted a significant reduction in the measured parameters. The effect of PAI on IL-2 activity was negligible. A suppressive effect of a PAI has been detected on the proliferation of PBMC from IVDA and HIV-1 positive individuals. This activity may be associated with the capacity of PAI to reduce HIV titers in infected PBMC cultures.     

Magnetic resonance cholangiopancreatography: a novel approach to the evaluation of suspected pancreaticobiliary neoplasms

BACKGROUND: Magnetic resonance cholangiopancreatography (MRCP) is a new noninvasive diagnostic method for pancreaticobiliary (PB) imaging without endoscopy, sedation, or iodinated contrast. The purpose of this study was to evaluate the ability of MRCP to depict pancreatic and biliary ductal anatomy compared to that of endoscopic retrograde cholangiopancreatography (ERCP) and to evaluate the ability of MRCP to accurately diagnose PB neoplasms. METHODS: Twenty patients had MRCP, and 17 also had ERCP. All studies were read prospectively by experienced reviewers blinded to other imaging data. Pathologic diagnosis was made in all patients. RESULTS: Bile duct dilatation seen by ERCP in 14 of 17 patients was correctly identified by MRCP in all 14 patients, and normal ducts were correctly identified by MRCP in the other 3 patients. The pancreatic duct was visible on MRCP in the pancreatic head in 17 of 20 patients, the body in 17 of 20 patients, and the tail in 15 of 20 patients. At ERCP, pancreatic duct dilatation was present in 11 cases and was identified by MRCP in 10 of them. Eighteen of 20 patients had malignant PB neoplasms. MRCP indicated PB neoplasm in 19 patients. Seventeen of these 19 patients had histologically confirmed malignant neoplasms pathologically, whereas 2 had benign pathology (both chronic pancreatitis). Among the 17 patients who also had ERCP, MRCP and ERCP correctly agreed on a final diagnosis of malignant neoplasm in 14 cases. In the three cases in which MRCP and ERCP disagreed on a final diagnosis, MRCP was correct in one and incorrect in two. CONCLUSIONS: MRCP can accurately and noninvasively delineate PB ductal anatomy and diagnose PB neoplasms comparably to ERCP. MRCP is an interesting new noninvasive method for evaluating patients with suspected PB neoplasms.     

The yeast HSM3 gene acts in one of the mismatch repair pathways

Mutants with enhanced spontaneous mutability (hsm) to canavanine resistance were induced by N-methyl-N-nitrosourea in Saccharomyces cerevisiae. One bearing the hsm3-1 mutation was used for this study. This mutation does not increase sensitivity to the lethal action of different mutagens. The hsm3-1 mutation produces a mutator phenotype, enhancing the rates of spontaneous mutation to canavanine resistance and reversions of lys1-1 and his1-7. This mutation increases the rate of intragenic mitotic recombination at the ADE2 gene. The ability of the hsm3 mutant to correct DNA heteroduplex is reduced in comparison with the wild-type strain. All these phenotypes are similar to ones caused by pms1, mlhl and msh2 mutations. In contrast to these mutations, hsm3-1 increases the frequency of ade mutations induced by 6-HAP and UV light. Epistasis analysis of double mutants shows that the PMS1 and HSM3 genes control different mismatch repair systems. The HSM3 gene maps to the right arm of chromosome II, 25 cM distal to the HIS7 gene. Strains that bear a deleted open reading frame YBR272c have the genetic properties of the hsm3 mutant. The HSM3 product shows weak similarity to predicted products of the yeast MSH genes (homologs of the Escherichia coli mutS gene). The HSM3 gene may be a member of the yeast MutS homolog family, but its function in DNA metabolism differs from the functions of other yeast MutS homologs.     

Massive ozone, PM study begins in Southern California

Air Quality.     

In-phase and out-of-phase MR imaging of bone marrow: prediction of neoplasia based on the detection of coexistent fat and water

OBJECTIVE: The purpose of this study was to determine if gradient-echo MR imaging with TEs selected with fat and water in phase and out of phase can help predict the likelihood of neoplastic or nonneoplastic lesions in bone marrow. SUBJECTS AND METHODS: Thirty consecutive patients with 31 suspected bone marrow lesions underwent MR imaging, including two spoiled gradient-echo sequences identical in all parameters except TE, which was chosen such that fat and water were either in phase or out of phase. Relative ratios of the abnormal bone marrow signal intensity and a control site on the in-phase and out-of-phase images were expressed. The images were also assessed independently by two reviewers who were unaware of the patients' identities and clinical histories. Reviewers assessed decreased marrow signal intensity relative to control sites on the out-of-phase and in-phase images. Pathologic confirmation was obtained in 16 patients (17 lesions); the remainder of patients had either established diagnoses or determination of benignity based on stability of findings at 1 year. Relative ratios were compared with the Student's t test and receiver operating characteristic (ROC) curve analysis, and the reviewers' scores were evaluated with ROC curve analysis. RESULTS: The relative signal-intensity ratios were 1.03 +/- 0.13 for the neoplastic group and 0.62 +/- 0.13 for the nonneoplastic group (p < .0001). ROC curve analysis of the signal-intensity ratios showed a z-score of .99. A ratio cutoff value of 0.81 resulted in a 95% sensitivity and a 95% specificity for detection of neoplasm. Both reviewers achieved 100% sensitivity and 94-100% specificity for detection of neoplasms. CONCLUSION: In-phase and out-of-phase gradient-echo MR imaging of bone marrow signal-intensity abnormalities can help predict the likelihood of neoplastic or nonneoplastic lesions.