Conductance of Distorted Carbon Nanotubes

We have calculated the effects of structural distortions of armchair carbon nanotubes on their electrical transport properties. We found that the bending of the nanotubes decreases their transmission function in certain energy ranges and leads to an increased electrical resistance. Electronic structure calculations show that these energy ranges contain localized states with significant $\sigma$-$\pi$ hybridization resulting from the increased curvature produced by bending. Our calculations of the contact resistance show that the large contact resistances observed for SWNTs are likely due to the weak coupling of the NT to the metal in side bonded NT-metal configurations.Comment: 5 pages RevTeX including 4 figures, submitted to PR

PRIMA subretinal wireless photovoltaic microchip implantation in non-human primate and feline models

Purpose To evaluate the surgical technique for subretinal implantation of two sizes of PRIMA photovoltaic wireless microchip in two animal models, and refine these surgical procedures for human trials. Methods Cats and Macaca fascicularis primates with healthy retina underwent vitrectomy surgery and were implanted with subretinal wireless photovoltaic microchip at the macula/central retina. The 1.5mm PRIMA chip was initially studied in feline eyes. PRIMA implant (2mm,1.5mm sizes) arrays were studied in primates. Feasibility of subretinal chip implantation was evaluated with a newly-developed surgical technique, with surgical complications and adverse events recorded. Results The 1.5mm implant was placed in the central retina of 11 feline eyes, with implantation duration 43-106 days. The 1.5mm implant was correctly positioned into central macula of 11 primate eyes, with follow-up periods of minimum 6 weeks (n = 11), 2 years (n = 2), and one eye for 3 years. One primate eye underwent multi-chip 1.5mm implantation using two 1.5mm chips. The 2mm implant was delivered to 4 primate eyes. Optical coherence tomography confirmed correct surgical placement of photovoltaic arrays in the subretinal space in all 26 eyes. Intraoperative complications in primate eyes included retinal tear, macular hole, retinal detachment, and vitreous hemorrhage that resolved spontaneously. Postoperatively, there was no case of significant ocular inflammation in the 1.5mm implant group. Conclusions We report subretinal implantation of 1.5mm and 2mm photovoltaic arrays in the central retina of feline and central macula of primate eyes with a low rate of device-related complications. The in vivo PRIMA implantation technique has been developed and refined for use for a 2mm PRIMA implant in ongoing human trials

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Home Intravenous Self-Injection of Antibiotic Therapy

The current medical climate has forced all health care providers to search for alternative methods for the delivery of health care. This search has led to the use of sites outside the conventional hospital walls for peritoneal dialysis, parenteral hyperalimentation, blood or blood product transfusions, etc. Home intravenous self-injection of antibiotics is such an alternative to prolonged and/or repeated hospitalization for patients requiring intravenous antibiotics administration only. This alternative was started as a pilot study and soon became a usual service in the Centre hospitalier de l’Université Laval following receipt of a grant from the National Health Research and Development Program. After careful development of inclusion/exclusion criteria and a teaching manual for patient and health care providers. and the standardization of medical. pharmaceutical and nursing approach, a clinical, psychosocial and economical analysis of patients who agreed to participate in a clinical study comparing the two methods of health care delivery (hospital versus home) was started. Patients who met inclusion/exclusion criteria, agreeing to finish their treatment at home instead of staying hospitalized to receive intravenous antibiotics only, were taught the various techniques of intravenous self-injection. Once they were judged to be able to self-administer the antibiotics, they were sent home with the material needed to carry on their treatment, To date, more than 100 patients have participated in the home-treatment, of which 50 were analyzed. The duration of home treatment varied from two days to several months. Most patients had osteomyelitis, septic arthritis, septic bursitis, bacterial cellulitis or lung infections. The therapy allowed some newly defined patients with complicated infections (AIDS patients with cytomegalovirus retinitis) to continue their treatment at home. The clinical outcome of patients treated at home was identical to the outcomes of those treated in the hospital. Side effects were comparable with the hospital treatment and were mainly catheter-related. Compared with hospitalization. home treatment was preferred by the majority of patients. Psychological analysis of the patients showed that those who choose home therapy had a higher internal “locus of control” than those who preferred to stay in the hospital for the entire length of therapy. The economical analysis showed a potential reduction of cost varying between $941.00 and$3325.00 per treatment. Home intravenous self-injection of antibiotics allowed health self-monitoring by the patients or/and their friends or family and increased health care efficiency

Monitoring Guidelines for Home and Outpatient Parenteral Antibiotic Therapy

When prescribing home intravenous antibiotic therapy (HIVAT), physicians must consider not only the factors normally considered in a hospital setting, but also the limitations and advantages of home therapy. Examples include dosage schedule, short and long term toxicity, stability of the antibiotics at room temperature after dilution, half-life of antibiotics, compatibility with other antibiotics or medications in the same bag and distribution methods from the supplier (pharmacy) to the patient. Consideration of these factors may direct antimicrobial choices, the mode of delivery and treatment schedule. Other prerequisites for antibiotic selection for home therapy include tolerability and low incidence of toxic reactions. Physicians and nurses must be aware of the adverse effects associated with prolonged outpatient intravenous antimicrobial therapy. Additional knowledge must include pharmacokinetics (absorption, distribution and elimination) and the pharmacodynamics (biochemical and physiological effects and mechanisms of action) of the commonly used antibiotics. One simple guideline is the less often a drug has to be administered, the more convenient the therapy will be for the patients, facilitating a higher rate of compliance. The less frequent administration schedules will also require less staff time for training and troubleshooting. Many antimicrobial agents can be given once daily and, therefore, readily meet this objective. Classes of antimicrobials that can be used once daily include aminoglycosides, ceftriaxone, vancomycin and the new quinolones. The development of antimicrobials that can be administered less often has been a major factor contributing to the growth of HIVAT. If an antibiotic has to be used more frequently than three times a day, the use of a computerized ambulatory infusion pump is helpful; however, pumps are expensive and not readily available. Other considerations for HIVAT include renal impairment, liver failure and hematological toxicities. These factors have led the author and colleagues to develop specific monitoring recommendations and techniques

Endovascular Treatment of Transverse-Sigmoid Sinus Type I Dural Arteriovenous Shunts with Sinus Preservation for Patients with Intolerable Symptoms: Four Case Reports

International audienc