Spin correlations and exchange in square lattice frustrated ferromagnets

The J1-J2 model on a square lattice exhibits a rich variety of different forms of magnetic order that depend sensitively on the ratio of exchange constants J2/J1. We use bulk magnetometry and polarized neutron scattering to determine J1 and J2 unambiguously for two materials in a new family of vanadium phosphates, Pb2VO(PO4)2 and SrZnVO(PO4)2, and we find that they have ferromagnetic J1. The ordered moment in the collinear antiferromagnetic ground state is reduced, and the diffuse magnetic scattering is enhanced, as the predicted bond-nematic region of the phase diagram is approached.Comment: 4 pages, 4 figure

Prevalence of sero-markers and non-invasive assessment of liver cirrhosis in patients with hepatitis B virus infection in Freetown, Sierra Leone: a cross-sectional study

BACKGROUND: Hepatitis B virus (HBV) is a major global health problem. Although sub-Saharan Africa has a high proportion of the global burden of HBV, the epidemiology and clinical features of HBV in this region are poorly characterized, and access to diagnostic and treatment services remain limited. METHODS: We conducted a retrospective study of HBV-infected children and adults of all age groups who were evaluated at public and private health facilities in Freetown, Sierra Leone between January 2017 and January 2019. We assessed their clinical presentation, HBV sero-markers, stages of liver disease, prevalence of cirrhosis by non-invasive tools, and the proportion of treatment eligible patients using the criteria recommended by the World Health Organization's 2015 treatment guidelines for HBV. Logistic regression was used to identify predictors of liver cirrhosis. RESULTS: 163 HBV patients included in the study, with mean age 32.6 years and 65.0% (106) being males. Most (84.0%) were asymptomatic at presentation. The majority (69.9%) were classified as having HBeAg-negative chronic infection (or inactive HBsAg carrier phase), 24.5% were in the HBeAg-negative immune active phase, 3.1% had HBeAg positive hepatitis, and 2.5% were HBsAg negative. The median Aspartate aminotransferase to Platelet Ratio (APRI) and Fibrosis-4 (FIB-4) scores were 0.37 and 0.80, respectively. The prevalence of cirrhosis was 7.6% and 6.2%, estimated by the APRI and FIB-4 scores, respectively. About 20.0% of patients were eligible for treatment with antiviral agents. Based on APRI scores, the presence of any symptom [adjusted odds ratio (aOR) 20.0, 95% confidence interval (CI) (4.1-85.9); p < 0.001], elevated direct bilirubin [aOR 12.1, 95% CI (1.9-63.0); p = 0.003], and elevated total bilirubin [aOR 16.1, 95% CI (3.2-80.8); p = 0.001] were independent predictors of cirrhosis. CONCLUSION: Although most patients with HBV infection were asymptomatic, the prevalence of liver cirrhosis and proportion of patients requiring antiviral treatment were substantial. This small study from a hyperendemic setting in Sierra Leone suggests that routine population-based screening may increase early detection and linkage of HBV patients to care before development of complications. Larger studies are needed to confirm our findings

Antiferromagnetic Order in MnO Spherical Nanoparticles

We have performed unpolarized and polarized neutron diffraction experiments on monodisperse 8 nm and 13 nm antiferromagnetic MnO nanoparticles. For the 8 nm sample, the antiferromagnetic transition temperature $T_N$ (114 K) is suppressed compared to the bulk material (119 K) while for the 13 nm sample $T_N$ (120 K) is comparable to the bulk. The neutron diffraction data of the nanoparticles is well described using the bulk MnO magnetic structure but with a substantially reduced average magnetic moment of 4.2$\pm$0.3 $\mu_B$/Mn for the 8 nm sample and 3.9$\pm$0.2 $\mu_B$/Mn for the 13 nm sample. An analysis of the polarized neutron data on both samples shows that in an individual MnO nanoparticle about 80$$ of Mn ions order. These results can be explained by a structure in which the monodisperse nanoparticles studied here have a core that behaves similar to the bulk with a surface layer which does not contribute significantly to the magnetic order.Comment: 7 pages, 5 figure

Non-surgical spinal decompression therapy: does the scientific literature support efficacy claims made in the advertising media?

<p>Abstract</p> <p>Background</p> <p>Traction therapy has been utilized in the treatment of low back pain for decades. The most recent incarnation of traction therapy is non-surgical spinal decompression therapy which can cost over $100,000. This form of therapy has been heavily marketed to manual therapy professions and subsequently to the consumer. The purpose of this paper is to initiate a debate pertaining to the relationship between marketing claims and the scientific literature on non-surgical spinal decompression.</p> <p>Discussion</p> <p>Only one small randomized controlled trial and several lower level efficacy studies have been performed on spinal decompression therapy. In general the quality of these studies is questionable. Many of the studies were performed using the VAX-D^®unit which places the patient in a prone position. Often companies utilize this research for their marketing although their units place the patient in the supine position.</p> <p>Summary</p> <p>Only limited evidence is available to warrant the routine use of non-surgical spinal decompression, particularly when many other well investigated, less expensive alternatives are available.</p

Discontinuous Transition from a Real Bound State to Virtual Bound State in a Mixed-Valence State of SmS

Golden SmS is a paramagnetic, mixed-valence system with a pseudogap. With increasing pressure across a critical pressure Pc, the system undergoes a discontinuous transition into a metallic, anti-ferromagnetically ordered state. By using a combination of thermodynamic, transport, and magnetic measurements, we show that the pseudogap results from the formation of a local bound state with spin singlet. We further argue that the transition Pc is regarded as a transition from an insulating electron-hole gas to a Kondo metal, i.e., from a spatially bound state to a Kondo virtually bound state between 4f and conduction electrons.Comment: 5 pages, 5 figure

Incidence and risk factors of surgical site infections and related antibiotic resistance in Freetown, Sierra Leone: a prospective cohort study

BACKGROUND: There is limited information on surgical site infections (SSI) and the related antibiotic resistance needed to guide their management and prevention in Sierra Leone. In this study, we aimed to establish the incidence and risk factors of SSI and the related antibiotic resistance among adults attending a tertiary hospital, and a secondary health facility in Freetown, Sierra Leone. METHODS: This is a prospective cohort study designed to collect data from adult (18 years or older) patients who attended elective and emergency surgeries at two hospitals in Freetown between February and July, 2021. Data analysis was done using STATA version 16. RESULTS: Of 338 patients, 245 (72.5%) and 93 (27.5%) had their surgeries at the tertiary and secondary hospitals, respectively. Many were males 192 (56.8%), less than 35 years 164 (48.5%), and 39 (11.5%) developed an SSI. Of the 39 patients who acquired an SSI, 7 (17.9%) and 32 (82.1%) had their surgeries at the secondary and tertiary hospitals, respectively. The incidence of SSI is higher in contaminated 17 (43.6%) than in clean-contaminated 12 (30.8%) and clean 10 (25.6%) wounds. Wound swabs were collected in 29 (74.4%) patients, of which 18 (62.1%) had bacterial growth. In total, 49 isolates of 14 different bacteria including gram-negative 41 (83.7%) and gram-positive 8 (16.3%) isolates were identified. Of these, 32 (65.3%) were Enterobacteriaceae, 9 (18.4%) were Non-fermenting gram-negative bacilli and 10 (12.2%) were Enterococci. The most common isolates were Escherichia coli (12, 24.5%), Klebsiella pneumoniae (10, 20.4%), Acinetobacter baumannii (5, 10.2%), Klebsiella oxytoca (4, 8.2%) and Enterococcus faecalis (4, 8.2%). The Enterobacteriaceae were either resistance to carbapenems (4, 8.2%) or were extended-spectrum beta-lactamase (ESBL) producing organisms (29, 59.2%). Male sex [p = 0.031], an ASA score >/= 2 [p = 0.020), administration of general anaesthesia [p = 0.018] and elevated fasting glucose [p = 0.033] were predictive of SSI. CONCLUSION: The incidence of SSI in this study is comparable to other low- and middle-income countries, but a substantial proportion of these postoperative wounds have an ESBL-producing Enterobacteriaceae. Therefore, routine surveillance of SSI and related antibiotic resistance is required in resource-limited settings

Establishing an antimicrobial stewardship program in Sierra Leone: a report of the experience of a low-income country in West Africa

Antimicrobial Resistance (AMR) is a growing global health challenge that threatens to undo gains in human and animal health. Prevention and control of AMR requires functional antimicrobial stewardship (AMS) program, which is complex and often difficult to implement in low- and middle-income countries. We aimed to describe the processes of establishing and implementing an AMS program at Connaught Hospital in Sierra Leone. The project involved the setting up of an AMS program, capacity building and performing a global point prevalence survey (GPPS) at Sierra Leone's national referral hospital. Connaught Hospital established a multidisciplinary AMS subcommittee in 2021 to provide AMS services such as awareness campaigns, education and training and review of guidelines. We performed a GPPS on 175 patients, of whom more than half (98, 56.0%) were prescribed an antibiotic: 63 (69.2%) in the surgical wards and 53 (51.2%) in the medical wards. Ceftriaxone (60, 34.3%) and metronidazole (53, 30.3%) were the most common antibiotics prescribed to patients. In conclusion, it is feasible to establish and implement an AMS program in low-income countries, where most hospitalized patients were prescribed an antibiotic