A study of transport suppression in an undoped AlGaAs/GaAs quantum dot single-electron transistor.

We report a study of transport blockade features in a quantum dot single-electron transistor, based on an undoped AlGaAs/GaAs heterostructure. We observe suppression of transport through the ground state of the dot, as well as negative differential conductance at finite source-drain bias. The temperature and magnetic field dependences of these features indicate the couplings between the leads and the quantum dot states are suppressed. We attribute this to two possible mechanisms: spin effects which determine whether a particular charge transition is allowed based on the change in total spin, and the interference effects which arise from coherent tunnelling of electrons in the quantum dot.

Impact of small-angle scattering on ballistic transport in quantum dots.

Disorder increasingly affects performance as electronic devices are reduced in size. The ionized dopants used to populate a device with electrons are particularly problematic, leading to unpredictable changes in the behavior of devices such as quantum dots each time they are cooled for use. We show that a quantum dot can be used as a highly sensitive probe of changes in disorder potential and that, by removing the ionized dopants and populating the dot electrostatically, its electronic properties become reproducible with high fidelity after thermal cycling to room temperature. Our work demonstrates that the disorder potential has a significant, perhaps even dominant, influence on the electron dynamics, with important implications for "ballistic" transport in quantum dots.

Toxicity in three dogs from accidental oral administration of a topical endectocide containing moxidectin and imidacloprid.

Three dogs were presented with a history of oral administration of a topical endectocide containing imidacloprid and moxidectin. They were diagnosed with imidacloprid and moxidectin intoxication, having ingested doses ranging from 7.5 to 1.4 mg/kg of imidacloprid and 1.9 to 2.8 mg/kg of moxidectin. The three dogs were affected to different degrees of severity, but all displayed signs of ataxia, generalised muscle tremors, paresis, hypersalivation and disorientation. Temporary blindness occurred in two cases. The three dogs were tested for the presence of the multi-drug resistance 1 gene deletion, which can cause an increased sensitivity to the toxic effects of moxidectin, and were found to be negative. Treatment included gastrointestinal decontamination, intravenous fluid therapy and benzodiazepines to control muscle tremors. All three dogs made a complete recovery within 48 h of ingestion.

Nonsurgical treatment of gastroesophageal intussusception in a puppy.

A 7-week-old, female Siberian husky was presented to Murdoch University Veterinary Hospital with an acute onset of respiratory distress and regurgitation. Thoracic imaging identified an intraluminal esophageal mass with concurrent aspiration pneumonia. Esophagoscopy identified the mass as stomach, and a diagnosis of gastroesophageal intussusception was made. The intussusception was reduced endoscopically, and fixation of the stomach to the abdominal wall was performed using a tube gastropexy. Gastroesophageal intussusception is an uncommon disease in small animals and traditionally has been managed surgically. This case report describes an alternative method of treatment associated with a good outcome in this puppy.

Activated coagulation times in normal cats and dogs using MAX-ACT tubes.

OBJECTIVE: To establish reference values for activated coagulation time (ACT) in normal cats and dogs, by visual assessment of clot formation using the MAX-ACT(TM) tube. SUBJECTS: We recruited 43 cats and 50 dogs for the study; 11 cats and 4 dogs were excluded from the statistical analysis because of abnormalities on clinical examination or laboratory testing including anaemia, prolonged prothrombin time (PT) or activated partial thromboplastin time (APTT), or insufficient plasma volume for comprehensive laboratory coagulation testing. PROCEDURE: Blood samples were collected via direct venipuncture for MAX-ACT, packed cell volume/total solids, manual platelet estimation and PT/APTT measurement. Blood (0.5 mL) was mixed gently in the MAX-ACT tube at 37 degrees C for 30 s, then assessed for clot formation every 5 to 10 s by tipping the tube gently on its side and monitoring for magnet movement. The endpoint was defined as the magnet lodging in the clot. The technique was tested with 10 dogs by collecting two blood samples from the same needle insertion and running a MAX-ACT on each simultaneously. RESULTS: In normal cats the mean MAX-ACT was 66 s (range 55-85 s). In normal dogs the mean was 71 s (range 55-80 s). There was no statistical difference between the first and second samples collected from the same needle insertion. CONCLUSIONS: and Clinical Relevance In both cats and dogs, a MAX-ACT result >85 s should be considered abnormal and further coagulation testing should be performed. Additionally, failure to discard the first few drops of the sample does not appear to significantly affect results.

Exposure-response functions in Air Force toxic risk modeling.

A new methodology for estimating the probabilistic risk from acute toxic exposures is planned as a support tool for the Air Force at the Eastern and Western Ranges. Two such methodologies are programs entitled the Launch Area Toxic Analysis program (LATRA) and the Cold Spill Toxic Risk Analysis program (COSTRA). These programs combine probabilistic models of an accident (when applicable), release cloud formation and dispersion (appropriate to the toxic substance and accounting for meteorological conditions), and new exposure-response functions (ERFs) for sensitive and normal exposed populations. These ERFs, anchored on specific exposure standards, estimate the probability of a given severity of health effect in a particular population as a function of the concentration or dose to which it is exposed. The further development and acceptance of these ERFs by the toxicology community, especially for different sensitivities, are key concerns addressed in this paper.