The quantum twisting microscope.

The invention of scanning probe microscopy revolutionized the way electronic phenomena are visualized1. Whereas present-day probes can access a variety of electronic properties at a single location in space2, a scanning microscope that can directly probe the quantum mechanical existence of an electron at several locations would provide direct access to key quantum properties of electronic systems, so far unreachable. Here, we demonstrate a conceptually new type of scanning probe microscope-the quantum twisting microscope (QTM)-capable of performing local interference experiments at its tip. The QTM is based on a unique van der Waals tip, allowing the creation of pristine two-dimensional junctions, which provide a multitude of coherently interfering paths for an electron to tunnel into a sample. With the addition of a continuously scanned twist angle between the tip and sample, this microscope probes electrons along a line in momentum space similar to how a scanning tunnelling microscope probes electrons along a line in real space. Through a series of experiments, we demonstrate room-temperature quantum coherence at the tip, study the twist angle evolution of twisted bilayer graphene, directly image the energy bands of monolayer and twisted bilayer graphene and, finally, apply large local pressures while visualizing the gradual flattening of the low-energy band of twisted bilayer graphene. The QTM opens the way for new classes of experiments on quantum materials.

Individual differences in TMS sensitivity influence the efficacy of tDCS in facilitating sensorimotor adaptation.

BACKGROUND: Transcranial direct current stimulation (tDCS) can enhance cognitive function in healthy individuals, with promising applications as a therapeutic intervention. Despite this potential, variability in the efficacy of tDCS has been a considerable concern. OBJECTIVE: /Hypothesis: Given that tDCS is always applied at a set intensity, we examined whether individual differences in sensitivity to brain stimulation might be one variable that modulates the efficacy of tDCS in a motor learning task. METHODS: In the first part of the experiment, single-pulse transcranial magnetic stimulation (TMS) over primary motor cortex (M1) was used to determine each participant's resting motor threshold (rMT). This measure was used as a proxy of individual sensitivity to brain stimulation. In an experimental group of 28 participants, 2 mA tDCS was then applied during a motor learning task with the anodal electrode positioned over left M1. Another 14 participants received sham stimulation. RESULTS: M1-Anodal tDCS facilitated learning relative to participants who received sham stimulation. Of primary interest was a within-group analysis of the experimental group, showing that the rate of learning was positively correlated with rMT: Participants who were more sensitive to brain stimulation as operationalized by our TMS proxy (low rMT), showed faster adaptation. CONCLUSIONS: Methodologically, the results indicate that TMS sensitivity can predict tDCS efficacy in a behavioral task, providing insight into one source of variability that may contribute to replication problems with tDCS. Theoretically, the results provide further evidence of a role of sensorimotor cortex in adaptation, with the boost from tDCS observed during acquisition.

Characterization of a Low Pathogenic Avian Influenza Virus (H6N1) Isolated from Turkeys.

An avian influenza virus (AIV), A/turkey/Israel/09 subtype H6N1, was isolated from turkey poults exhibiting typical pathology associated with AIV infection. The virus was characterized by RT-PCR using AIV subtype-specific primers and by the haemagglutination inhibition test using AIV subtype-specific antisera. The virus has an intravenous pathogenicity index of 0 and possessed a nucleotide sequence at the cleavage site of the hemagglutinin gene, PQIETR*GLF, associated with avian influenza viruses of low pathogenicity. Unlike the two previous H6N2 isolates originating from domestic ducks and mallard, the A/turkey/Israel/09 (H6N1) was isolated from turkeys. The gene sequences of the A/turkey/Israel/09 (H6N1) virus show divergence from the former Israeli H6 isolates.

Polymyxin B: pharmacokinetics of single doses given intravenously and intramuscularly to turkeys, and minimal inhibitory concentrations for Escherichia coli and Pasteurella multocida.

The 50% and 90% minimal inhibitory concentrations (MIC50 and MIC90) of polymyxin B for avian Escherichia coli and Pasteurella multocida isolates were determined by the agar plate dilution method. Polymyxin B at approximate MIC level in serum was bactericidal for E. coli in 2 to 4 hours. Aqueous polymyxin B sulfate was administered by a single bolus intravenous injection into turkeys at 10,000 IU/kg, and by a single bolus intramuscular injection at 5,000, 10,000 or 20,000 IU/kg. Effective serum drug concentrations after intramuscular injection (MIC50 levels or greater) were maintained for E. coli for 7.0 hr (10,000 IU/kg) and 11.5 hr (20,000 IU/kg), and for P. multocida for 3.0 hr (10,000 IU/kg) and 4.1 hr (20,000 IU/kg). Pharmacokinetic parameters were calculated by non-compartmental methods. Elimination time half-lives, mean residence time, clearance, and apparent volume of distribution at steady state (Vdss) were all much higher for i.m. injection of 20,000 IU/kg than for i.m. injection of 10,000 IU/kg. We postulate that there exists a minimal tissue-interaction threshold concentration (MTC) at which polymyxin B can enter previously unavailable compartments or bind to previously refractory tissue components. Bioavailability of polymyxin B injected i.m. was 0.904 for the 10,000 IU/kg dose and 0.675 for the 20,000 IU/kg dose. Dosage intervals necessary to produce minimal steady state concentrations (Cssmin) equal to the MIC were calculated. Certain aspects of the use of the parameter Vdss, and limitations on the use of dosage interval calculations for polymyxin B, are discussed. One week after i.m. injection of polymyxin B at 10,000 IU/kg, high tissue drug levels were present, especially in bound form in liver. Following single injections, no toxic effects on turkeys were observed.

Muscovy ducks as a source of Pasteurella anatipestifer infection in turkey flocks.

An outbreak of disease, characterised by neurological signs and increased mortality, occurred in 17 out of 50 turkey farms in a village. Virological tests were negative as were routine bacteriological tests of the organs. However, Pasteurella anatipestifer was repeatedly isolated from the brain. The source of the infection was probably a group of Muscovy ducks.

Diagnostic radiology in disaster medicine: implications for design, planning and organization of X-ray departments.

Diagnostic radiology plays an important role in the evaluation of disaster casualties; these are referred to X-ray departments, shortly after their arrival at hospital, in large numbers, frequently overwhelming facilities and resources of the department. The study of relevant literature and the experience of the authors suggest that there are implications for design, planning and organization of X-ray departments to be considered in disaster-prone areas. Departments should be sited as near as possible to triage areas, on the same floor, with broad, unobstructed passages. There should be provision for easy passage of equipment and trolleys through doors and corridors and large circulation areas, working rooms and waiting spaces with plugs, for electricity, piped oxygen and suction and devices for hanging infusion sets. Two entrances to the department would enable one-way flow through the department. All work should be done in the department and examinations performed with mobile units avoided. A radiologist at the entrance to the department and a control post at the exit ensure adequate processing of casualties. Interpretation and reporting should be done by assigned radiologists dictating directly to typists; films and reports should accompany casualties.

Immunoelectrophoresis of avian viral proteins in a phosphate-buffered system.

Avian influenza and hemorrhagic enteritis viral preparations were immunoelectrophoresed in a phosphate-buffered system. Excellent separation and resolution of viral proteins were achieved. Reasons are given why this method might be preferred over the conventional method employing a veronal (barbital)-buffered system.