Magnetism in semiconducting molybdenum dichalcogenides.

Transition metal dichalcogenides (TMDs) are interesting for understanding the fundamental physics of two-dimensional (2D) materials as well as for applications to many emerging technologies, including spin electronics. Here, we report the discovery of long-range magnetic order below T M = 40 and 100 K in bulk semiconducting TMDs 2H-MoTe2 and 2H-MoSe2, respectively, by means of muon spin rotation (µSR), scanning tunneling microscopy (STM), and density functional theory (DFT) calculations. The µSR measurements show the presence of large and homogeneous internal magnetic fields at low temperatures in both compounds indicative of long-range magnetic order. DFT calculations show that this magnetism is promoted by the presence of defects in the crystal. The STM measurements show that the vast majority of defects in these materials are metal vacancies and chalcogen-metal antisites, which are randomly distributed in the lattice at the subpercent level. DFT indicates that the antisite defects are magnetic with a magnetic moment in the range of 0.9 to 2.8 µB. Further, we find that the magnetic order stabilized in 2H-MoTe2 and 2H-MoSe2 is highly sensitive to hydrostatic pressure. These observations establish 2H-MoTe2 and 2H-MoSe2 as a new class of magnetic semiconductors and open a path to studying the interplay of 2D physics and magnetism in these interesting semiconductors.

Early versus late stages of processing and their relation to functional hemispheric asymmetries in face recognition.

To determine whether perceptual asymmetries for faces occur at early or late stages of stimulus analysis, subjects compared the members of a pair of faces which appeared in the right or left visual field, either to each other or to a previously presented sample. The first two experiments established that manual reaction times were consistently shorter to left-field presentation only when test faces were compared for identity to a memorized sample (Experiment 2), but not when they were compared to each other (Experiment 1). By varying the interstimulus interval between the sample and test (Experiment 3), it was found that a consistent left-field superiority was absent for at least the first 50 msec following sample offset, suggesting that during that time both hemispheres have access to a short-lived, visual trace that represents the results of the early, precategorical processing stages. Beyond 100 msec, or earlier if the trace is degraded by a masking field (Experiment 4), a left-field advantage is observed. Experiment 5 showed that higher order comparisons between photographs and caricatures yield a left-field superiority even in a memory-free situation. Together, the results indicate only higher order processes, such as are needed to maintain a relatively permanent memory representation or to compare caricatures with photographs, require the specialized functions peculiar to the right hemisphere. Lower-order, precategorical processes seem to be common to both hemispheres.

Case report: extrathoracic herniation of the lung with a review of the literature.

A case of extrathoracic herniation of the lung is described together with the radiological findings in this condition including the role of computed tomography (CT) in its management. In addition a review of the literature is presented which outlines the incidence, classification and clinical features of lung herniae. Some reference is made to possible methods of treatment.

The validity and reliability of hand-held dynamometry in assessing isometric external rotator performance.

The validity and reliability of hand-held dynamometry and Cybex dynamometry were investigated using maximal isometric contractions of the external rotators of the shoulder in 14 healthy male subjects. Three maximum voluntary contractions were recorded from each subject by a hand-held dynamometer and a Cybex isokinetic dynamometer at two testing sessions approximately 1 week apart. Analysis of variance did not reveal any significant differences between the mean peak torques obtained with either instrument or between days. The intrarater reliability was clearly established for both the hand-held dynamometer (r = 0.986) and Cybex dynamometer (r = 0.993). Within-day correlations between the two instruments accounted for 27% (day 1) and 60% (day 2) of the explainable variance. This suggests that although both techniques produced identical peak torque values and measured the same element of performance-strength, they did so in a slightly different manner. The possible nature of these differences is discussed.J Orthop Sports Phys Ther 1988;10(6):213-217.

The use of air or CO2 as insufflation agents for double contrast barium enema (DCBE): is there a qualitative difference?

One hundred consecutive out-patients referred for double contrast barium enema (DCBE) were randomized in a double-blind prospective study to receive either air or CO2 as an insufflation agent. Each examination was performed by the same radiologist and radiographer. The two groups were equally matched for age and sex. Each completed examination was independently assessed by three radiologists for a variety of parameters. The results show that the patients receiving air as an insufflation agent had better overall colonic distension than the group receiving CO2 and that this was statistically significant (P = 0.0004). There was no significant difference in the mean time taken to perform the examination in the two groups nor was there any significant difference in mucosal coating or preparation. In conclusion, our results suggest that poor colonic distension is a potential problem when CO2 is used for DCBE and that this cannot be solely attributed to the time taken to perform the examination. Poor distension could lead to diagnostic errors and this may outweigh the advantages in patient acceptability when using CO2 as an insufflation agent.

Pancreatic abnormalities and AIDS related sclerosing cholangitis.

OBJECTIVES: Biliary tract abnormalities are well recognised in AIDS, most frequently related to opportunistic infection with Cryptosporidium, Microsporidium, and cytomegalovirus. We noted a high frequency of pancreatic abnormalities associated with biliary tract disease. To define these further we reviewed the clinical and radiological features in these patients. METHODS: Notes and radiographs were available from two centres for 83 HIV positive patients who had undergone endoscopic retrograde cholangiopancreatography for the investigation of cholestatic liver function tests or abdominal pain. RESULTS: 56 patients had AIDS related sclerosing cholangitis (ARSC); 86% of these patients had epigastric or right upper quadrant pain and 52% had hepatomegaly. Of the patients with ARSC, 10 had papillary stenosis alone, 11 had intra- and extrahepatic sclerosing cholangitis alone, and 35 had a combination of the two. Ampullary biopsies performed in 24 patients confirmed an opportunistic infection in 16. In 15 patients, intraluminal polyps were noted on the cholangiogram. Pancreatograms were available in 34 of the 45 patients with papillary stenosis, in which 29 (81%) had associated pancreatic duct dilatation, often with associated features of chronic pancreatitis. In the remaining 27 patients, final diagnoses included drug induced liver disease, acalculous cholecystitis, gall bladder empyema, chronic B virus hepatitis, and alcoholic liver disease. CONCLUSION: Pancreatic abnormalities are commonly seen with ARSC and may be responsible for some of the pain not relieved by biliary sphincterotomy. The most frequent radiographic biliary abnormality is papillary stenosis combined with ductal sclerosis.