Single electron charging of impurity sites visualized by scanning gate experiments on a quantum point contact

A quantum point contact (QPC) patterned on a two-dimensional electron gas is investigated with a scanning gate setup operated at a temperature of 300 mK. The conductance of the point contact is recorded while the local potential is modified by scanning the tip. Single electron charging of impurities induced by the local potential is observed as a stepwise conductance change of the constriction. By selectively changing the state of some of these impurities, it is possible to observe changes in transmission resonances of the QPC. The location of such impurities is determined, and their density is estimated to be below 50 per \mu m^2, corresponding to less than 1 % of the doping concentration

Squid have nociceptors that display widespread long-term sensitization and spontaneous activity after bodily injury

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Neuroscience 33 (2013): 10021-10026, doi:10.1523/JNEUROSCI.0646-13.2013.Bodily injury in mammals often produces persistent pain that is driven at least in part by long-lasting sensitization and spontaneous activity (SA) in peripheral branches of primary nociceptors near sites of injury. While nociceptors have been described in lower vertebrates and invertebrates, outside of mammals there is limited evidence for peripheral sensitization of primary afferent neurons, and there are no reports of persistent SA being induced in primary afferents by noxious stimulation. Cephalopod molluscs are the most neurally and behaviorally complex invertebrates, with brains rivaling those of some vertebrates in size and complexity. This has fostered the opinion that cephalopods may experience pain, leading some governments to include cephalopods under animal welfare laws. It is not known, however, if cephalopods possess nociceptors, or whether their somatic sensory neurons exhibit nociceptive sensitization. We demonstrate that squid possess nociceptors that selectively encode noxious mechanical but not heat stimuli, and that show long-lasting peripheral sensitization to mechanical stimuli after minor injury to the body. As in mammals, injury in squid can cause persistent SA in peripheral afferents. Unlike mammals, the afferent sensitization and SA are almost as prominent on the contralateral side of the body as they are near an injury. Thus, while squid exhibit peripheral alterations in afferent neurons similar to those that drive persistent pain in mammals, robust changes far from sites of injury in squid suggest that persistently enhanced afferent activity provides much less information about the location of an injury in cephalopods than it does in mammals.This work was supported by NSF Grants IOS-1146987 to E.T.W. and IOS-1145478 to R.T.H., and the Baxter Pharmaceuticals Fellowship and Bang Summer Research Fellowship from the Marine Biological Laboratory to R.J.C.2013-12-1

Polo like kinase 2 tumour suppressor and cancer biomarker: new perspectives on drug sensitivity/resistance in ovarian cancer

The polo-like kinase PLK2 has recently been identified as a potential theranostic marker in the management of chemotherapy sensitive cancers. The methylation status of the PLK2 CpG island varies with sensitivity to paclitaxel and platinum in ovarian cancer cell lines. Importantly, extrapolation of these in vitro data to the clinical setting confirms that the methylation status of the PLK2 CpG island predicts outcomes in patients treated with carboplatin and paclitaxel chemotherapy. A second cell cycle regulator, p57Kip2, is also subject to epigenetic silencing in carboplatin resistance in vitro and in vivo, emphasising that cell cycle regulators are important determinants of sensitivity to chemotherapeutic agents and providing insights into the phenomenon of collateral drug sensitivity in oncology. Understanding the mechanistic basis and identification of robust biomarkers to predict collateral sensitivity may inform optimal use of chemotherapy in patients receiving multiple lines of treatment

Are food exposures obtained through commercial market panels representative of the general population? Implications for outbreak investigations

Current methods of control recruitment for case-control studies can be slow (a particular issue for outbreak investigations), resource-intensive and subject to a range of biases. Commercial market panels are a potential source of rapidly recruited controls. Our study evaluated food exposure data from these panel controls, compared with an established reference dataset. Market panel data were collected from two companies using retrospective internet-based surveys; these were compared with reference data from the National Diet and Nutrition Survey (NDNS). We used logistic regression to calculate adjusted odds ratios to compare exposure to each of the 71 food items between the market panel and NDNS participants. We compared 2103 panel controls with 2696 reference participants. Adjusted for socio-demographic factors, exposure to 90% of foods was statistically different between both panels and the reference data. However, these differences were likely to be of limited practical importance for 89% of Panel A foods and 79% of Panel B foods. Market panel food exposures were comparable with reference data for common food exposures but more likely to be different for uncommon exposures. This approach should be considered for outbreak investigation, in conjunction with other considerations such as population at risk, timeliness of response and study resources

Kombinierte dorsale und palmare Plattenosteosynthese bei distalen intraartikulären Radiusfrakturen

Zusammenfassung: Hintergrund: Behandlungsziel bei komplexen distalen intraartikulären Radiusfrakturen ist die anatomische Gelenkrekonstruktion. In seltenen Fällen kann dies nur mit einer kombinierten, dorsalen und palmaren Abstützung erreicht werden, trotz der zunehmenden Erfahrung mit winkelstabilen palmaren Implantaten. Diese retrospektive Qualitätskontrollstudie untersucht das funktionelle, radiologische und subjektive Outcome der mit dieser Technik operierten Patienten. Patienten und Methoden : An der Klinik für Unfallchirurgie des Universitätsspital Zürich wurden zwischen März 1999 und Januar 2003 von 360 Patienten mit instabiler distaler Radiusfraktur 30 Patienten mit komplexer C2-/C3-Fraktur über einen kombinierten dorsopalmaren Zugang mit einer 3,5-mm-T-Platte und dorsal mit zwei 1/4-Rohr-Platten behandelt und in die Studie eingeschlossen (9 Frauen, 21Männer, Mittelwert des Alters 52). Nachkontrolliert werden konnten 25 der 30 Patienten im Mittel 29 Monate nach Unfall. Ergebnisse: Die angestrebte anatomische Rekonstruktion gelang nicht bei allen Patienten: 56% zeigten leichte, 28% schwere Zeichen der Arthrose. Die Flexion erreichte 66%, die Extension 75% der gesunden Seite, Pronation und Supination sogar 98 bzw. 91%. Die Kraft beim Faustschluss betrug 75% der kontralateralen Seite. Zehn Patienten (40%) entwickelten im Verlauf ein komplexes regionales Schmerzsyndrom (CRPS). Die Rückkehr zur Arbeit war nach 120 Tagen möglich. Schlussfolgerung: Die dorsopalmare Plattenosteosynthese komplexer, distaler intraartikulärer Radiusfrakturen erlaubt eine Gelenkrekonstruktion mit gutem subjektivem, funktionellem und radiologischem Resultat, dies trotz des durch den beidseitigen Zugang verursachten zusätzlichen Weichteilschaden. Das hohe CRPS-Risiko, aber auch der lange Arbeitsausfall müssen bei der Patientenaufklärung berücksichtigt werde

Triplet Irradiance Measurements

Cloud speed and direction govern the dynamic nature of irradiance, and hence the electrical output of PV panels and arrays. For example, ramp rates are directly proportional to the cloud speed and related to the coincidence of cloud direction and array orientation. In this work, we demonstrate that cloud dynamics can be determined using a triplet of silicon irradiance sensors logged at high frequency. Using cross-correlation, cloud speed and direction are calculated from the time shifts of cloud edges detected from sensor pairs. Data was initially recorded for 5 months from March 2016, near Leeds, UK. Further data will be recorded in 2018, near Kampala, Uganda. From the 2016 data, minimum cloud speeds of 4 ms-1 and a maximum of 40 ms-1 were obtained while dominant direction was found to be from the west-northwest. Comparison was then made to hourly wind speed and direction data recorded at 10 m above the ground level from the Bingley SAMOS weather station which is located 4 km away from the triplet of irradiance sensors. Cloud speed is invariably higher than the 10 m wind speed, on account friction between air and the earth’s surface. Nevertheless, we report a strong linear relationship between cloud speed and 10 m wind speed, with a correlation coefficient, R, of 0.9. Regarding comparison of direction, a deflection of 22.50 in the cloud direction clockwise of 10 m wind direction was observed as the dominant ground level wind direction was found to be from the west, while the dominant direction of the clouds was found to be from the west-northwest. Ramp rates were determined and compared with 10 m wind speeds. A low to moderate positive correlation were observed with a minimum and maximum correlation coefficient, R, of 0.2095 and 0.4274 in June and April respectively. These correlations are understood to have been diminished because of noise and solar irradiance reflected and focused onto the sensors by various cloud sides. This work demonstrates that both triplets of irradiance sensors and ground level wind data are useful and low-cost methods for predicting the likely frequency and magnitude of ramp rates of PV arrays

A Millikelvin Scanned Probe for Measurement of Nanostructures

We demonstrate a scanning force microscope, based upon a quartz tuning fork, that operates below 100 mK and in magnetic fields up to 6 T. The microscope has a conducting tip for electrical probing of nanostructures of interest, and it incorporates a low noise cryogenic amplifier to measure both the vibrations of the tuning fork and the electrical signals from the nanostructures. At millikelvin temperatures the imaging resolution is below 1 um in a 22 um x 22 um range, and a coarse motion provides translations of a few mm. This scanned probe is useful for high bandwidth measurement of many high impedance nanostructures on a single sample. We show data locating an SET within an array and measure its coulomb blockade with a sensitivity of 2.6 x 10^-5 e/Hz^1/2.Comment: 5 pages, 5 figures, submitted to RS