Direct observation of vortices in an electron fluid.

Vortices are the hallmarks of hydrodynamic flow. Strongly interacting electrons in ultrapure conductors can display signatures of hydrodynamic behaviour, including negative non-local resistance1-4, higher-than-ballistic conduction5-7, Poiseuille flow in narrow channels8-10 and violation of the Wiedemann-Franz law11. Here we provide a visualization of whirlpools in an electron fluid. By using a nanoscale scanning superconducting quantum interference device on a tip12, we image the current distribution in a circular chamber connected through a small aperture to a current-carrying strip in the high-purity type II Weyl semimetal WTe2. In this geometry, the Gurzhi momentum diffusion length and the size of the aperture determine the vortex stability phase diagram. We find that vortices are present for only small apertures, whereas the flow is laminar (non-vortical) for larger apertures. Near the vortical-to-laminar transition, we observe the single vortex in the chamber splitting into two vortices; this behaviour is expected only in the hydrodynamic regime and is not anticipated for ballistic transport. These findings suggest a new mechanism of hydrodynamic flow in thin pure crystals such that the spatial diffusion of electron momenta is enabled by small-angle scattering at the surfaces instead of the routinely invoked electron-electron scattering, which becomes extremely weak at low temperatures. This surface-induced para-hydrodynamics, which mimics many aspects of conventional hydrodynamics including vortices, opens new possibilities for exploring and using electron fluidics in high-mobility electron systems.

Let us unite against COVID-19 - a New Zealand perspective.

Novel coronavirus 2019 (COVID-19) has shaken the existence of mankind worldwide, including that of New Zealand. In comparison to other countries, New Zealand has had a very low number of confirmed and probable cases as well as COVID-19-related deaths. New Zealand closed its borders and rapidly declared a stringent lockdown to eliminate COVID-19. The country's 'go hard, go early' policy serves as an exemplar for the rest of the world to date. The mysterious nature of COVID-19 has caused tremendous stress and uncertainty leading to universal conflict between public health and state economy. Mental health services and non-government organisations have been proactive in the fight against COVID-19. Though there has been no significant rise in referrals to secondary mental health services to date (4 May 2020), a rapid surge in mental health presentations is widely anticipated. Telehealth may prove to be an efficient and cost-effective tool for the provision of future health services.

Emergent nanoscale superparamagnetism at oxide interfaces.

Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.

Comparison of outcomes after endovascular and open repair of abdominal aortic aneurysms in low-risk patients.

BACKGROUND: In randomized trials endovascular aortic aneurysm repair (EVAR) has been shown to have superior perioperative outcomes compared with open aneurysm repair (OAR). However, outcomes in patients at low risk of complications are unclear and many surgeons still prefer OAR in this cohort. The objective was to analyse perioperative and longer-term outcomes of OAR and EVAR in this low-risk group of patients. METHODS: All elective infrarenal EVARs and OARs in the Vascular Study Group of New England database were reviewed from 2003 to 2014. The Medicare scoring system was used to identity patients at low risk of perioperative complications and death. Perioperative and longer-term outcomes were analysed in this cohort. A Kaplan-Meier plot was constructed for evaluation of longer-term survival. Further propensity matching and multivariable analysis were performed to analyse additional differences between the two groups. RESULTS: Some 1070 patients who underwent EVAR and 476 who had OAR were identified. Mean(s.d.) age was 67·3(5·7) and 65·1(6·3) years respectively (P < 0·001). EVAR was associated with a lower overall perioperative complication rate (4·2 versus 26·5 per cent; P < 0·001). There was no difference in 30-day mortality (0·4 versus 0·6 per cent; P = 0·446). Overall survival at 3 years was similar after EVAR and OAR (92·5 versus 92·1 per cent respectively; P = 0·592). In multivariable analyses there was no difference in freedom from reintervention (odds ratio 1·69, 95 per cent c.i. 0·73 to 3·90; P = 0·220) or survival (hazard ratio 0·85, 0·61 to 1·20; P = 0·353). CONCLUSION: In patients predicted to be at low risk of perioperative death following aneurysm repair, EVAR resulted in fewer perioperative complications than OAR. However, perioperative mortality, reinterventions and survival rates in the longer term appeared similar between endovascular and open repair.

Imaging murine NALT following intranasal immunization with flagellin-modified circumsporozoite protein malaria vaccines.

Intranasal (IN) immunization with a Plasmodium circumsporozoite (CS) protein conjugated to flagellin, a Toll-like receptor 5 agonist, was found to elicit antibody-mediated protective immunity in our previous murine studies. To better understand IN-elicited immune responses, we examined the nasopharynx-associated lymphoid tissue (NALT) in immunized mice and the interaction of flagellin-modified CS with murine dendritic cells (DCs) in vitro. NALT of immunized mice contained a predominance of germinal center (GC) B cells and increased numbers of CD11c+ DCs localized beneath the epithelium and within the GC T-cell area. We detected microfold cells distributed throughout the NALT epithelial cell layer and DC dendrites extending into the nasal cavity, which could potentially function in luminal CS antigen uptake. Flagellin-modified CS taken up by DCs in vitro was initially localized within intracellular vesicles followed by a cytosolic distribution. Vaccine modifications to enhance delivery to the NALT and specifically target NALT antigen-presenting cell populations will advance development of an efficacious needle-free vaccine for the 40% of the world's population at risk of malaria.

Donor brain death inhibits tolerance induction in miniature swine recipients of fully MHC-disparate pulmonary allografts.

We have previously shown that a short course of high-dose tacrolimus induces long-term tolerance to fully mismatched lung allografts procured from healthy MHC-inbred miniature swine. Here, we investigate whether donor brain death affects tolerance induction. Four recipient swine were transplanted with fully mismatched lung grafts from donors that were rendered brain dead and mechanically ventilated for 4 h before procurement (Group 1). These recipients were compared to two control groups (Group 2: 4 h of donor ventilation without brain death [n = 5]; and Group 3: no donor brain death with <1 h of ventilation [n = 6]). All recipients were treated with a 12-day course of tacrolimus. In contrast to both groups of control animals, the swine transplanted with lung allografts from brain dead donors all rejected their grafts by postoperative day 45 and showed persistent responsiveness to donor antigen by MLR. Several additional swine underwent brain death induction and/or mechanical ventilation alone to determine the effects of these procedures on the expression of proinflammatory molecules. Significant increases in serum concentrations of IL-1, TNF-α and IL-10 were seen after brain death. Upregulation of IL-1 and IL-6 gene expression was also observed.

Minimally invasive surgery for thoracoabdominal aortic aneurysms.

Open surgical repair of thoracoabdominal aortic aneurysms (TAAA) remains a highly morbid procedure. In recent years, several minimally invasive techniques have been introduced to treat TAAA. These include hybrid procedures and purely endovascular approaches using modified aortic endografts. Although still investigational, this burgeoning technology has the potential to improve outcomes in TAAA repair, as well as to circumvent the morbidity and mortality associated with the traditional surgical approach to TAAA. While the reported experience is limited to several institutional case series, results are encouraging, and suggest that fenestrated and branched endografts are likely to figure prominently in the management of TAAA in the future. An overview of these minimally invasive techniques, as well as the role of computer-assisted imaging analysis, is provided.

Ocular bacillary angiomatosis in an immunocompromised man.

An immunocompromised man presented with an inflammatory eyelid lesion. Biopsy was performed; histopathology and special staining confirmed a diagnosis of bacillary angiomatosis. The man was treated with oral erythromycin, and the lesion resolved. The etiologic agents of bacillary angiomatosis are Bartonella henselae and Bartonella quintana, Gram-negative coccobacilli. The organisms stain positively with the Warthin-Starry silver stain. Lesions can be cutaneous or visceral and have been commonly described in immunocompromised patients. Histopathologic examination of lesions reveals angiogenesis and cellular proliferation. Bacillary angiomatosis can be treated with oral antibiotics.

The indirect alloresponse impairs the induction but not maintenance of tolerance to MHC class I-disparate allografts.

We studied the effects of indirect allorecognition on the induction and maintenance phases of tolerance in miniature swine cotransplanted with heart and kidney allografts. MHC class I-mismatched heart and kidney grafts were cotransplanted in recipients receiving CyA for 12 days. Recipients were unimmunized or immunized with a set of donor-derived or control third-party MHC class I peptides either 21 days prior to transplantation or over 100 days after transplantation. T-cell proliferation, delayed type hypersensitivity reaction (DTH) and antibody production were assessed. All animals injected with donor MHC class I peptides developed potent indirect alloresponses specific to the immunizing peptides. While untreated recipients developed stable tolerance, all animals preimmunized with donor allopeptides rejected kidney-heart transplants acutely. In contrast, when peptide immunization was delayed until over 100 days after kidney-heart transplantation, no effects were observed on graft function or in vitro measures of alloimmunity. Donor peptide immunization prevented tolerance when administered to recipients pre transplantation but did not abrogate tolerance when administered to long-term survivors post transplantation. This suggests that the presence of T cells activated via indirect allorecognition represent a barrier to the induction but not the maintenance of tolerance.

Preferential transmission of interleukin-1 receptor antagonist alleles in attention deficit hyperactivity disorder.

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, where family data support substantial heritability.(1) To date, association studies focussed mainly on genes regulating dopaminergic neurotransmission.(2)Interleukin-1 (IL-1) activity in the brain has been implicated with differentiation of dopaminergic neurons(3,4) and modulation of central monoaminergic reactivity.(5) We investigated the role of interleukin-1 receptor antagonist (IL-1Ra) gene variable number tandem repeat (VNTR) polymorphism,(6) in a sample of 86 children with DSM-IV ADHD and their parents. Transmission disequilibrium analysis showed increased transmission of the IL-1Ra 4-repeat allele (chi(2) = 4.07, P = 0.04) and decreased transmission of the 2-repeat allele (chi(2) = 4.59, P = 0.03) to affected children. The 4-repeat allele was associated with a significantly increased risk for ADHD (chi(2) = 4.46, df 1, P = 0.035, RR = 1.292, 95% CI 1.01-1.66). The IL-1Ra 2-repeat allele was associated with a significantly decreased risk for ADHD (chi(2) = 4.65, df 1, P = 0.03, RR = 0.763, 95% CI 0.59-0.98). If replicated, this finding may point to a role for brain cytokine activity in the etiopathogenesis of ADHD.

Testosterone concentrations, testes weight and morphology of mule drakes (Muscovy drake x Khaki Campbell).

1. Mule ducks were produced by naturally mating Muscovy drakes and Khaki Campbell ducks. 2. Semen was collected from 6-month-old mule drakes via an artificial vagina. The fluid was clear without any spermatozoa or spermatids. 3. Testes from 27-week-old mule drakes were smaller in size than those of Khaki Campbell drakes but heavier than Muscovy males of the same age. Histological sections of these testes revealed that spermatogenesis was not complete. 4. Testosterone concentration in the mule drakes was higher than in Muscovy males but similar to Khaki Campbell drakes. 5. Mule drakes have strong sexual drives as a result of high concentrations of testosterone, but, because spermatogenesis is incomplete, their semen had no sperm.

Association between diabetes and elevated serum alanine aminotransferase activity among Mexican Americans.

Elevated activities of serum aminotransferases are a common sign of liver disease and are observed more frequently among diabetics than in the general population. Whether this association is due to confounding factors is unknown. The authors investigated whether diabetes was significantly associated with elevated serum activity of alanine aminotransferase (ALT) after adjustment for factors common to both diabetes and raised ALT. Data from 2,999 men and women aged 20-74 years representative of the Mexican American population of the southwestern United States were obtained from the Hispanic Health and Nutrition Examination Survey (1982-1984). Approximately 6% of men and 2% of women had elevated serum ALT activity (>43 IU/liter). The odds ratio for diabetes as a predictor of elevated ALT was 4.1 (95% confidence interval 2.3-7.6) adjusted for age and sex, which decreased to 3.0 (95% confidence interval 0.92-9.74) after adjustment for age, sex, body mass index, alcohol consumption, and other factors. In addition to diabetes, body mass index was also significantly (p < 0.05) associated with elevated ALT activity. Heavier alcohol consumption and male sex increased the likelihood of elevated ALT, whereas coffee consumption reduced it. Diabetes and liver injury appear to be associated, even with control for factors in common.

Three-dimensional microplate-enhanced alveolar ridge augmentation--an alternative to nerve transposition.

The placement of endosseous implants in the atrophic posterior mandible has presented a challenge to the surgeon and restorative dentist. Traditional procedures either require nerve transposition or utilization of implants placed at less than favorable angles. A technique is presented for the three-dimensional augmentation of the atrophic alveolar ridge utilizing microplate-enhanced guided bone regeneration technology. The applications of this technique in other intraoral and extraoral sites are currently under investigation by the authors.

Biological monitoring of exposure to cadmium, a human carcinogen, as a result of active and passive smoking.

Cadmium (Cd), a known human carcinogen, is one of the components of tobacco and also has many industrial uses. Smoking Cd-contaminated cigarettes at work may cause an increase in blood levels and toxicity of Cd. For a population of nonexposed workers, we compared blood Cd and urine cotinine (Cot) levels as biological markers of exposure to cigarette smoke of active smokers (AS) and passive smokers (PS) with those of unexposed nonsmokers (UNS) in 158 workers. The mean Cd in AS (0.097 microgram%; ie, 0.097 microgram/100 mL whole blood) was significantly higher than in UNS (0.085 microgram%), and was very close to the mean Cd levels in PS (0.093 microgram%). Mean Cd levels in exposed past smokers (0.105 microgram% was higher than in nonexposed past smokers (P < 0.05) and in AS. The mean Cot level was significantly higher in AS than in PS or in UNS. Increased smoking was associated directly with increased blood Cd and urine Cot. Our results supported and proved quantitatively that exposure to cigarette smoke is harmful to both AS and PS, as we show that in both cases there is an increase in blood Cd. According to our results, exposure to cigarette smoke via active and passive smoking increases blood Cd by an average of 0.01 micrograms% over the background (UNS). We conclude that exposure to cigarette smoke is a confounder to be taken into account when carrying out epidemiological studies and surveillance programs on workers exposed to Cd at work.

Cellular and secretory mechanisms related to delayed radiation-induced microvessel dysfunction in the spinal cord of rats.

PURPOSE: This study aimed to investigate long-term, radiation-induced changes in microvessel permeability, the profile of the vasoactive mediators endothelin and nitric oxide, and the response of specific cell systems in the irradiated spinal cord of rats. METHODS AND MATERIALS: The thoracolumbar spinal cords of Fischer rats were irradiated to a dose of 15 Gy, and the rats were sacrificed at various times afterward. Endothelin levels and nitric oxide-synthase (NOS) activity were assayed in extracts of spinal cords. Microvascular permeability and the effect of treatment with recombinant human manganese superoxide dismutase (r-hMnSOD) were assessed quantitatively. Immunohistochemistry evaluated astrocytes, microglia, vascular basal membrane, and neurofilaments. RESULTS: None of the rats developed neurologic dysfunction. Endothelin levels were significantly reduced at 18 h after irradiation and markedly attenuated after 10 days (p < 0.007). Thereafter, endothelin levels returned to normal values at 56 days after radiation and escalated to markedly high levels after 120 and 180 days (p < 0.002). NOS activity remained very low throughout the period of follow-up and failed to counterbalance the shifts in endothelin levels. Treatment with r-hMnSOD had no effect on normal vascular permeability but it abolished the abnormally increased permeability measured at 18 h after radiation and again after 120 and 180 days. Standard microscopic evaluation failed to reveal abnormalities in the irradiated spinal cord, but immunohistochemical staining showed a progressive increase in the number of microglial cells per field after 120 and 180 days (p < 0003). A similar increase in the number of astrocytic cells per field was noted after more than 180 days, but an earlier short lasting peak was also noted at 14 days after radiation. No abnormalities were found in blood vessel configuration, density, diameter, and basal membrane staining, or in the neurofilaments. CONCLUSION: Marked imbalance in the regulatory function of endothelium-derived mediators of the vascular tone is present after radiation therapy probably inducing chronic vasoconstriction. This imbalance favors localized procoagulation that may enhance the consequent loss of function measured as increased permeability. Microglial proliferation may account for continuous release of superoxide that may enhance disruption of normal permeability. The latter is corrected by SOD treatment. Astrocytic proliferation may present a response to the mitogenic effect of endothelin and to microglial-derived paracrine effect of cytokines.

Month-of-birth and incidence of acute lymphoblastic leukemia in children.

As a means of examining the virus-relatedness of acute lymphoblastic leukemia (ALL) in children, we investigated the association between month-of-birth and the occurrence of ALL in 1487 children aged 0-15 years at the time of diagnosis. Our hypothesis being that evidence of seasonal variation in births of ALL cases would suggest exposure to a transmissible etiologic agent during the perinatal period. The data were obtained from the Surveillance, Epidemiology, and End Results (SEER) Program and consisted of children diagnosed during the years 1973-1986. Aggregate monthly incidence rates of ALL stratified by month-of-birth, for each SEER site, all sites combined, and for broad geographic regions were calculated. No evidence for an association between month-of-birth and childhood ALL was found.

Correlations with self-reported weight loss in overweight U.S. adults.

The authors investigated two issues among overweight men and women in the U.S.: 1) what is the influence of the self-expressed intention to lose weight in the presence of other potential predictors of loss and 2) what are easily identifiable predictors of intentional weight loss during a 1-year recall period. The sample consisted of 1996 overweight men (body mass index (BMI > or = 27.8 kg/m2) and 2586 overweight women (BMI > or = 27.3 kg/m2) who answered questions regarding 1-year weight change in a Current Health Topic supplement of the population-based 1989 National Health Interview Survey. Of these overweight persons, 56.8% of men and 72.1% of women attempted to lose weight during the previous year. The most important characteristic associated with weight loss was the expressed intention itself. For any weight loss, the odds ratios (95% confidence intervals) for intention were 4.6 (3.6-5.9) for men and 3.8 (2.8-5.0) for women. Controlling for other factors reduced the odds only slightly, to 4.3 for men and 3.5 for women. Among women, older age, having a greater frequency of blood pressure checks, and being in poorer health reduced the influence of intent as a predictor of loss. To address the second objective, the identification of predictors of intentional 1-year weight loss, analysis was restricted to overweight persons who attempted to lose weight. For both sexes, statistically significant predictors (p < 0.05) included never being married, smoking, higher BMI, being diabetic, and having a higher number of blood pressure checks. Being divorced or separated was predictive of weight loss in men only. Also, men were more likely to achieve weight loss than women. In conclusion, 1-year weight loss among the overweight was primarily a function of the intention to lose weight, although other factors contributed to determine whether weight loss was achieved.