Bulk and Surface Electronic Structure of the Dual-Topology Semimetal Pt_{2}HgSe_{3}.

We report high-resolution angle-resolved photoemission measurements on single crystals of Pt_{2}HgSe_{3} grown by high-pressure synthesis. Our data reveal a gapped Dirac nodal line whose (001) projection separates the surface Brillouin zone in topological and trivial areas. In the nontrivial k-space range, we find surface states with multiple saddle points in the dispersion, resulting in two van Hove singularities in the surface density of states. Based on density-functional theory calculations, we identify these surface states as signatures of a topological crystalline state, which coexists with a weak topological phase.

Magnetic 2D materials and heterostructures.

The family of two-dimensional (2D) materials grows day by day, hugely expanding the scope of possible phenomena to be explored in two dimensions, as well as the possible van der Waals (vdW) heterostructures that one can create. Such 2D materials currently cover a vast range of properties. Until recently, this family has been missing one crucial member: 2D magnets. The situation has changed over the past 2 years with the introduction of a variety of atomically thin magnetic crystals. Here we will discuss the difference between magnetic states in 2D materials and in bulk crystals and present an overview of the 2D magnets that have been explored recently. We will focus on the case of the two most studied systems-semiconducting CrI3 and metallic Fe3GeTe2-and illustrate the physical phenomena that have been observed. Special attention will be given to the range of new van der Waals heterostructures that became possible with the appearance of 2D magnets, offering new perspectives in this rapidly expanding field.

Probing magnetism in 2D materials at the nanoscale with single-spin microscopy.

The discovery of ferromagnetism in two-dimensional (2D) van der Waals (vdW) crystals has generated widespread interest. Making further progress in this area requires quantitative knowledge of the magnetic properties of vdW magnets at the nanoscale. We used scanning single-spin magnetometry based on diamond nitrogen-vacancy centers to image the magnetization, localized defects, and magnetic domains of atomically thin crystals of the vdW magnet chromium(III) iodide (CrI3). We determined the magnetization of CrI3 monolayers to be ≈16 Bohr magnetons per square nanometer, with comparable values in samples with odd numbers of layers; however, the magnetization vanishes when the number of layers is even. We also found that structural modifications can induce switching between ferromagnetic and antiferromagnetic interlayer ordering. These results demonstrate the benefit of using single-spin scanning magnetometry to study the magnetism of 2D vdW magnets.

Two-dimensional Mott-Hubbard electrons in an artificial honeycomb lattice.

Artificial crystal lattices can be used to tune repulsive Coulomb interactions between electrons. We trapped electrons, confined as a two-dimensional gas in a gallium arsenide quantum well, in a nanofabricated lattice with honeycomb geometry. We probed the excitation spectrum in a magnetic field, identifying collective modes that emerged from the Coulomb interaction in the artificial lattice, as predicted by the Mott-Hubbard model. These observations allow us to determine the Hubbard gap and suggest the existence of a Coulomb-driven ground state.

Role of magnetic resonance imaging in the detection of anastomotic biliary strictures after liver transplantation.

INTRODUCTION: Biliary complications after orthotopic liver transplantation (OLT) are the principal cause of morbidity and graft dysfunction, ranging in incidence from 5.8% to 30% of cases. Biliary strictures are the most frequent type of late complication. The aim of this study was to evaluate the role of magnetic resonance cholangiography (MRC) to detect biliary anastomotic strictures among patients undergone OLT with abnormal liver function tests. MATERIALS AND METHODS: One hundred twenty-one of 300 patients who underwent OLT were evaluated by MRC for clinically suspected anastomotic biliary strictures. In all patients, we performed various precholangiographic sequences including T1- and T2-weighted and MRC (radial SE 2D and SS-TSE 3D). Magnetic resonance imaging findings were subdivided as absence or presence of an anastomotic stricture. Diagnostic confirmation was obtained by endoscopic retrograde cholangiography (n=32), percutaneous transhepatic cholangiography (n=21) or surgical treatment (n=18). RESULTS: MRC detected 56 anastomotic biliary strictures, 53 of which were confirmed by other imaging modalities. MRC showed two false-negative cases and three false-positive cases. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRC to detect biliary strictures were 96%, 96%, 95%, 97%, and 96%, respectively. CONCLUSION: MRC proved to be a reliable noninvasive technique to visualize the biliary anastomosis and depict biliary strictures after OLT. MRC should be used when a biliary anastomotic stricture is suspected in an OLT patient.

Role of magnetic resonance cholangiography in biliary complications of orthotopic liver transplantation.

PURPOSE: The aim of this study was to evaluate the role of magnetic resonance cholangiography (MRC) in the detection of biliary complications following orthotopic liver transplantation (OLT). MATERIALS AND METHODS: Seventy-eight transplant patients with clinically suspected biliary complications were evaluated with 1.5-T magnetic resonance imaging (MRI) using a surface coil. All patients were imaged with the following sequences: axial T1-weighted and axial and coronal T2-weighted, 2D spin echo (SE) breath-hold radial cholangiography, and coronal 3D single-shot turbo spin echo (SS-TSE) with respiratory triggering. Patients with negative MRI underwent clinical and sonographic followup. When biliary complications were present, diagnostic confirmation was obtained by endoscopic retrograde cholangiopancreatography (ERCP) (n=13), percutaneous transhepatic cholangiography (PTC) (n=20), ultrasonography (n=10) or computed tomography (CT) (n=2). In 11 cases, surgical confirmation was also obtained. RESULTS: MRC detected biliary complications in 44/78 patients, in particular, 42 biliary strictures (37 anastomotic and five intrahepatic), 40 of which were confirmed by other imaging modalities. In 25/37 cases of anastomotic stricture, preanastomotic dilatation of the biliary tract was also demonstrated. Other MRC-detected biliary complications were biliary sludge (n=4), biloma (n=5), and biliary stones (n=3). In four cases, PTC revealed biliary complications that had not been detected with MRC (false negative results). In two cases, MRC showed unconfirmed strictures of the intrahepatic ducts and biliodigestive anastomosis (false positive results). The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and diagnostic accuracy of MRC were 93.5%, 94.4%, 96.7%, 89.5% and 93.9%, respectively. CONCLUSIONS: Our results confirm that MRC is a reliable technique for depicting biliary anastomoses and detecting biliary complications after OLT. The high diagnostic accuracy of MRC indicates that this examination should be routinely employed in all OLT patients with clinically suspected biliary complications.

Self-report of circadian type reflects the phase of the melatonin rhythm.

This study examined the relationship between circadian rhythm characteristics of the pineal hormone melatonin and individual differences in circadian type and mood. 95 healthy young men and 22 women were assessed each hour (00:00-07:00 h) for blood levels of melatonin throughout one night in the laboratory. Each subject was assessed for circadian type (morning, afternoon, or evening type) and morning mood (PANAS). Circadian type was strongly related to the melatonin acrophase but not to amplitude or time of year of assessment. Also, morning types evidenced a more rapid decline in melatonin levels after the peak than did evening types. Evening types were younger than were morning types. Female morning types reported more positive affect upon waking than did female afternoon or evening types. Males showed no such discrimination. Age was related to both melatonin acrophase and circadian type but did not explain the relationship between them. The results replicate and extend findings on circadian type and psychological and physiological variables.

Cytokines and cognitive behavior.

Proinflammatory cytokines help orchestrate host responses to infection and are a major communication link between peripheral immunity and the CNS. These cytokines initiate a number of CNS events that culminate in both physiological and behavioral changes. Peripheral IL-1beta also affects information processing. A series of experiments examining the effect of learning intensity, motivation, and cytokine dose are reported. Using a well-established Morris water maze (MWM) system with female C57BL/6 mice, we report that (1) IL-1 (100 ng/mouse, i.p.) has no effect on MWM learning when mice are subjected to a spaced as opposed to a massed learning protocol; (2) water temperature is critical to the IL-1 effect on learning insofar as IL-1 interferes with learning in a warm-water but not a cold-water maze, and (3) higher doses (1,000 ng/mouse, i.p.) of IL-1 in experimental systems known to produce the IL-1-induced learning deficit with lower doses (100 ng/mouse, i.p.) show consistent facilitation, not impairment, of learning.

Human behavioral assessment in neurotoxicology: producing appropriate test performance with written and shaping instructions.

Neurotoxic effects are of such breadth and complexity that functional biomarkers (behavioral tests) that integrate many areas of the nervous system predominate in human neurotoxicology research. The increasing distribution of chemical and other manufacturing throughout the world, particularly in developing nations, suggests the acute need to develop biomarkers for chemical exposures and effects that can be employed internationally. A language-free method for training performance on behavioral tests is described, which holds promise for international research that circumvents the vagaries of translation. Four behavioral tests were administered to 74-114 adult US subjects. Procedures, collectively termed shaping, produced effective performance on three tests [Symbol Digit, Vigilant Attention Test (VAT), Digit Span Forward and Backward], and produced appropriate but unacceptably slow performance in initial testing on the Simple Reaction Time test. Effective performance on the Symbol-Digit test also was produced by shaping instruction, without assistance from examiners, in small groups of residents of Taipei (Taiwan) and US children between the ages of 5 and 16.

Selective approaches to basic neurobehavioral testing of children in environmental health studies.

To identify neurotoxic effects in children living near hazardous waste sites, the Agency for Toxic Substances and Disease Registry (ATSDR) has designed a basic Pediatric Environmental Neurobehavioral Test Battery (PENTB) for children 1 through 16 years of age. It emphasizes tests appropriate to the stages of a child's development. These stages were fundamental factors in selecting tests for the PENTB, which includes both informant- and performance-based assessment procedures. Assessment of children under 4 years of age is restricted to four informant-based instruments, to evaluate as many functions as possible while minimizing testing time and the professional expertise needed in the test setting. The assessment of children 4 through 16 years of age includes 10 performance-based tests to evaluate key functions within the cognitive, motor, and sensory domains analogous to functions affected by neurotoxic chemicals in adults. In all age groups, it is crucial to also assess family, cultural, economic, and other potentially confounding variables.

Legionella pneumophila-induced visual learning impairment reversed by anti-interleukin-1 beta.

Infecting mice with the opportunistic intracellular pathogen Legionella pneumophila markedly inhibited place learning of infected C57BL/6 mice as determined by the Morris water maze test. Mice infected with L. pneumophila evinced much less ability to learn the position of a hidden platform than did normal noninfected mice, which quickly learned the location of the hidden platform and escaped from the cool water of the pool with increasing efficiency. However, infected mice treated with anti-interleukin-1 (anti-IL-1) neutralizing antibody learned the task with about the same efficiency as the controls. When the animals were tested 1 week after learning, control animals remembered the task well and were able to escape with near maximal efficacy. On the other hand, L. pneumophila-infected mice performed as poorly after the 1 week rest as during the training period, indicating that infection blocked learning and not merely performance. Mice infected with L. pneumophila and given the antibody treatment were found to be indistinguishable from controls in that they remembered the task and escaped with good efficiency. Thus, the results of this study suggest that the pro-inflammatory cytokine, IL-1 beta, is involved, at least partly, in the attenuation of spatial navigational learning in mice infected acutely with a sublethal concentration of L. pneumophila. These results, therefore, suggest that cognitive impairment of L. pneumophila-infected mice may be related to the cytokine IL-1 beta and, furthermore, that cytokines may be related to learning and memory changes experienced by individuals suffering acute bacterial infections.

Spatial learning impairment in mice infected with Legionella pneumophila or administered exogenous interleukin-1-beta.

The effect of interleukin-1 beta (IL 1 beta) on spatial learning was examined. In one experiment, C57BL/6 mice were given daily injections (100 ng/mouse) of recombinant murine IL1 beta prior to training on the Morris water maze. In another experiment, mice were infected with a sublethal dose of a gram-negative bacterium (Legionella pneumophila; Lp). Mice rendered ill by the infection were given either anti-IL1 beta antibodies (100 micrograms/mouse) or saline and then trained on the water maze. Results indicated that (1) exogenous IL1 beta blocked acquisition of spatial learning, (2) Lp infection attenuated learning on this task, and (3) neutralizing circulating IL1 beta in Lp-infected mice normalized learning despite the continuation of the illness. The data indicate that cognitive impairment may be a component of cytokine-mediated sickness behavior.

IL-1 beta and TNF alpha modulate delta 9-tetrahydrocannabinol-induced catalepsy in mice.

The role of the proinflammatory cytokines interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF alpha) in THC-induced catalepsy in mice was examined. Recombinant IL-1 beta (400 ng/mouse, IV) and TNF alpha (500 ng/mouse, IV) were effective in potentiating the cataleptic effect of low-dose THC (10 micrograms/mouse, IV). Recombinant IL-1 alpha and IL-6 did not potentiate catalepsy at any dose tested. Anti-IL-1 beta and anti-TNF alpha antibodies were effective in attenuating high-dose (75 micrograms/mouse) THC-induced catalepsy. Antibodies to IL-1 alpha and IL-6 had no effect on catalepsy. Early onset catalepsy (10 min postinjection) was potentiated by exogenous recombinant IL-1 beta and TNF alpha but only later catalepsy (2 h postinjection) was attenuated by antibodies to endogenous IL-1 beta or TNF alpha. This divergence of the cytokine effect suggests that these substances regulate, by different mechanisms, the early and late THC-induced cataleptic response.

Influence of physician communication on newly diagnosed breast patients' psychologic adjustment and decision-making.

BACKGROUND: Physician-patient communication is of critical importance when a breast cancer diagnosis is made, because the emotionally overwhelmed patient must be educated about her disease and available treatments so she can participate in decisions about her care. A research study addressed the hypothesis that patients whose surgeons used psychotherapeutic techniques during the cancer diagnostic interview would have better psychologic adjustment to their cancer. METHODS: One hundred women surveyed 6 months after surgery completed the Cancer Diagnostic Interview Scale (CDIS) and the SCL-90-R, a measure of psychologic well being. RESULTS: Factor analysis of the CDIS revealed that the physician's caring attitude was perceived by the women as most important, with information-giving as a much weaker component. Multiple regression analysis supported the hypothesis that psychologic adjustment was predicted by physician behavior during the cancer diagnostic interview. Other significant predictors of adjustment were a history of psychiatric problems and premorbid life stressors. CONCLUSIONS: Provision of information needed for decision-making appears to be valued largely within the context of a caring physician-patient relationship. Specific surgeons' behaviors believed to facilitate patient adjustment include expressing empathy, allowing sufficient time for patients to absorb the cancer diagnosis, providing information, and engaging the patient in treatment decision-making.

Psychosocial aspects of melanoma.

Seventy-five patients with melanoma were surveyed for recent history of major stress, coping styles, and psychiatric disturbance. Recurrence of disease was strongly related to biological variables (stage and Breslow depths) but not to psychological measures. Major life stress was not related to stage, Breslow, Clark level, or estimates of lymphocytic infiltration of tumor. Coping styles were paradoxically related to major life stress such that history of major stresses was associated with greater confrontation of the melanoma diagnosis, greater will to fight the disease, and less avoidance of its frightening aspects. Experience with fewer major life stresses was associated with a defeatist attitude characterized by an expectation of a poor prognosis and little control over outcomes. More than 50% of the sample had experienced at least one major life stress in the past 5 years. This figure is consistent with prior work and indicative of a higher than normal rate of major life stress in the years before diagnosis.

Peer support group for adolescents with chronic illness.

This study assessed the effects of a monthly peer support group for adolescents with cancer and other hematological diseases. These adolescents shared activities and experiences with nondisabled high school students. At the group's conclusion, the adolescents reported that the group helped them cope with their illness and improved the quality of their daily lives. Nondisabled students reported that the group favorably affected their attitudes about, and intended behavior toward, peers with chronic illnesses. These results suggest that such groups can provide important benefits for individuals with chronic illnesses as well as for their nondisabled peers.

Impact of a hospital smoking ban: changes in tobacco use and employee attitudes.

The authors investigated the impact of a complete smoking ban on 349 employees of a cancer treatment center. A questionnaire administered approximately 4 months after the ban was initiated queried smokers on the impact of the ban on their smoking habits, their experience of withdrawal symptoms during the workday, and changes in work habits. A separate questionnaire asked nonsmokers about changes in the work environment. Results showed that few smokers quit while a majority decreased their consumption. Withdrawal symptoms were a problem in less than half the smokers, but those reporting signs of physical dependency on nicotine tended to smoke more before and after work and reported negative changes in work performance. Nonsmokers in general reported positive effects on the work environment.

Active-duty and veteran alcoholics: differences in psychopathology presentation.

The present study examines the differences in the presentation of psychopathology between active duty military and veteran patients enrolled in alcohol rehabilitation programs. The Millon Clinical Multiaxial Inventory was used to assess personality disorders, clinical syndromes, and substance abuse. Most veterans were seen as having avoidant and dependent personality disorders as well as a great deal of anxiety and depression. Forty-seven percent were above cutoff scores for alcohol abuse. Air Force patients were predominantly narcissistic and antisocial with much less distress. Only 9% were classified psychometrically as abusers. The results indicate that not only are veteran alcoholics more chronic but that active-duty alcohol abusers are underreporting abuse and care must be used in their assessment.

Factor-based special scales for the MCMI.

Factor analytic work with the Million Clinical Multiaxial Inventory (MCMI) has shown a remarkably stable factor structure. The eight Basic Personality scales have a three-factor structure: Aloof/Social, Submissive/Aggressive, and Labile/Restrained. These dimensions appear to be the same as those suggested by the DSM-III-R advisory committee on personality disorders. The MCMI as a whole has a five-factor structure: Detached, Submissive, Suspicious, High Social Energy, and General Distress. The present work operationalizes these two sets of factors into scales for use by clinicians and researchers. The resultant scales show excellent reliabilities across three subject samples (N = 253, N = 185, N = 184) and demonstrate appropriate convergent and divergent validity estimates against the MCMI itself.