Resonant tunneling diodes as sources for millimeter and submillimeter wavelengths

High-quality Resonant Tunneling Diodes have been fabricated and tested as sources for millimeter and submillimeter wavelengths. The devices have shown excellent I-V characteristics with peak-to-valley current ratios as high as 6:1 and current densities in the range of 50-150 kA/cm(exp 2) at 300 K. Used as local oscillators, the diodes are capable of state of the art output power delivered by AlGaAs-based tunneling devices. As harmonic multipliers, a frequency of 320 GHz has been achieved by quintupling the fundamental oscillation of a klystron source

A record-linkage study of the development of hepatocellular carcinoma in persons with hepatitis C infection in Scotland

We investigated trends in first time hospital admissions and deaths attributable to hepatocellular carcinoma (HCC) in a large population based cohort of 22 073 individuals diagnosed with hepatitis C viral (HCV) infection through laboratory testing in Scotland in 1991 2006. We identified new cases of HCC through record linkage to the national inpatient hospital discharge database and deaths registry. A total of 172 persons diagnosed with HCV were admitted to hospital or died with first time mention of HCC. Hepatocellular carcinoma incidence increased between 1996 and 2006 (average annual change of 6.1, 95% confidence interval (CI):0.9 11.6%, P¼0.021). The adjusted relative risk of HCC was greater for males (hazard ratio¼2.7, 95% CI: 1.7 4.2), for those aged 60 years or older (hazard ratio ¼2.7, 95% CI: 1.9 4.1) compared with 50 59 years, and for those with a previous alcohol related hospital admission (hazard ratio¼2.5, 95% CI: 1.7 3.7). The risk of individuals diagnosed with HCV developing HCC was greatlyincreased compared with the general Scottish population (standardised incidence ratio¼127, 95% CI: 102 156). Owing to the advancing age of the Scottish HCV diagnosed population, the annual number of HCC cases is projected to increase, with a consequent increasing burden on the public healthcare system

Examining trends in the incidence of HIV infection among people with a history of drug use to inform an outbreak investigation and response: a retrospective cohort study

Background: In the context of an outbreak of HIV among people who inject drugs in Glasgow, Scotland, identified in 2015, our objectives were to: (1) develop epidemiological methods to estimate HIV incidence using data linkage, and (2) examine temporal changes in HIV incidence to inform public health responses. Methods: This was a retrospective cohort study involving data linkage of laboratory HIV testing data to identify individuals with a history of drug use. Person-years (PY) and Poisson regression were used to estimate incidence by time period (pre-outbreak: 2000–2010 and 2011–2013; early outbreak: 2014–2016; ongoing outbreak: 2017–2019). Results: Among 13 484 individuals tested for HIV, 144 incident HIV infections were observed from 2000 to 2019. Incidence rates increased from pre-outbreak periods (1.00/1000 PY (95% confidence interval, CI: 0.60–1.65) in 2000–2010 and 1.70/1000 PY (95% CI: 1.14–2.54) in 2011–2013) to 3.02/1000 PY (95% CI: 2.36–3.86) early outbreak (2014–2016) and 2.35 (95% CI 1.74–3.18) during the ongoing outbreak period (2017–2019). Compared with the pre-outbreak period (2000–2010), the incidence rates were significantly elevated during both the early outbreak (2014–16) (adjusted incidence rate ratio (aIRR) = 2.87, 95% CI: 1.62–5.09, p &lt; 0.001) and the ongoing outbreak periods (2017–19) (aIRR = 2.12, 95% CI: 1.16–3.90, p = 0.015). Conclusions: Public health responses helped to curb the rising incidence of HIV infection among people with a history of drug use in Glasgow, but further efforts are needed to reduce it to levels observed prior to the outbreak. Data linkage of routine diagnostic test data to assess and monitor incidence of HIV infection provided enhanced surveillance, which is important to inform outbreak investigations and guide national strategies on elimination of HIV transmission.</p

Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis

Background People who inject drugs (PWID) experience a high prevalence of incarceration and might be at high risk of HIV and hepatitis C virus (HCV) infection during or after incarceration. We aimed to assess whether incarceration history elevates HIV or HCV acquisition risk among PWID. Methods In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO databases for studies in any language published from Jan 1, 2000 until June 13, 2017 assessing HIV or HCV incidence among PWID. We included studies that measured HIV or HCV incidence among community-recruited PWID. We included only studies reporting original results and excluded studies that evaluated incident infections by self-report. We contacted authors of cohort studies that met the inclusion or exclusion criteria, but that did not report on the outcomes of interest, to request data. We extracted and pooled data from the included studies using random-effects meta-analyses to quantify the associations between recent (past 3, 6, or 12 months or since last follow-up) or past incarceration and HIV or HCV acquisition (primary infection or reinfection) risk among PWID. We assessed the risk of bias of included studies using the Newcastle-Ottawa Scale. Between-study heterogeneity was evaluated using the I2 statistic and the P-value for heterogeneity. Findings We included published results from 20 studies and unpublished results from 21 studies. These studies originated from Australasia, western and eastern Europe, North and Latin America, and east and southeast Asia. Recent incarceration was associated with an 81% (relative risk [RR] 1·81, 95% CI 1·40–2·34) increase in HIV acquisition risk, with moderate heterogeneity between studies (I2=63·5%; p=0·001), and a 62% (RR 1·62, 95% CI 1·28–2·05) increase in HCV acquisition risk, also with moderate heterogeneity between studies (I2=57·3%; p=0·002). Past incarceration was associated with a 25% increase in HIV (RR 1·25, 95% CI 0·94–1·65) and a 21% increase in HCV (1·21, 1·02–1·43) acquisition risk. Interpretation Incarceration is associated with substantial short-term increases in HIV and HCV acquisition risk among PWID and could be a significant driver of HCV and HIV transmission among PWID. These findings support the need for developing novel interventions to minimise the risk of HCV and HIV acquisition, including addressing structural risks associated with drug laws and excessive incarceration of PWID

Individual-level needle and syringe coverage in Melbourne, Australia: a longitudinal, descriptive analysis

BACKGROUND: Coverage is used as one indicator of needle and syringe program (NSP) effectiveness. At the individual level, coverage is typically defined as an estimate of the proportion of a person who injects drugs’ (PWID) injecting episodes that utilise a sterile syringe. In this paper, we explore levels of individual syringe coverage and its changes over time. METHODS: Data were extracted from 1889 interviews involving 502 participants drawn from the Melbourne drug user cohort study (MIX). We asked questions relating to participants syringe acquisition, distribution and injecting frequency within the two weeks before interview. We created a dichotomous coverage variable that classified participants as sufficiently (≥100 %) covered if all their injecting episodes utilised at least one sterile syringe, and insufficiently (<100 %) covered if not. We categorised participants as “consistently covered” if they were sufficiently covered across interviews; as “consistently uncovered” if they were insufficiently covered across interviews; and “inconsistently covered” if they oscillated between coverage states. Chi-square statistics tested proportions of insufficient coverage across sub-groups using broad demographic, drug use and service utilisation domains. Logistic regression tested predictors of insufficient coverage and inconsistently covered categorisation. RESULTS: Across the sample, levels of insufficient coverage were substantial (between 22–36 % at each interview wave). The majority (50 %) were consistently covered across interviews, though many (45 %) were inconsistently covered. We found strong statistical associations between insufficient coverage and current hepatitis C virus (HCV) infection (RNA+). Current prescription of opioid substitution therapy (OST) and using NSPs as the main source of syringe acquisition were protective against insufficient coverage. CONCLUSION: Insufficient coverage across the sample was substantial and mainly driven by those who oscillated between states of coverage, suggesting the presence of temporal factors. We recommend a general expansion of NSP services and OST prescription to encourage increases in syringe coverage. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12913-016-1668-z) contains supplementary material, which is available to authorized users

Best-of-Three Contests: Experimental Evidence

We conduct an experimental analysis of a best-of-three Tullock contest. Intermediate prizes lead to higher efforts, while increasing the role of luck (as opposed to effort) leads to lower efforts. Both intermediate prizes and luck reduce the probability of contest ending in two rounds. The patterns of players‟ efforts and the probability that a contest ends in two rounds is consistent with „strategic momentum‟, i.e. momentum generated due to strategic incentives inherent in the contest. We do not find evidence for „psychological momentum‟, i.e. momentum which emerges when winning affects players‟ confidence. Similar to previous studies of contests, we find significantly higher efforts than predicted and strong heterogeneity in effort between subjects

Incidence of HIV and hepatitis C virus among people who inject drugs, and associations with age and sex or gender: a global systematic review and meta-analysis

BACKGROUND: Measuring the incidence of HIV and hepatitis C virus (HCV) infection among people who inject drugs (PWID) is key to track progress towards elimination. We aimed to summarise global data on HIV and primary HCV incidence among PWID and associations with age and sex or gender.METHODS: In this systematic review and meta-analysis, we updated an existing database of HIV and HCV incidence studies among PWID by searching MEDLINE, Embase, and PsycINFO, capturing studies published between Jan 1, 2000, and Dec 12, 2022, with no language or study design restrictions. We contacted authors of identified studies for unpublished or updated data. We included studies that estimated incidence by longitudinally re-testing people at risk of infection or by using assays for recent infection. We pooled incidence and relative risk (RR; young [generally defined as ≤25 years] vs older PWID; women vs men) estimates using random-effects meta-analysis and assessed risk of bias with a modified Newcastle-Ottawa scale. This study is registered with PROSPERO, CRD42020220884.FINDINGS: Our updated search identified 9493 publications, of which 211 were eligible for full-text review. An additional 377 full-text records from our existing database and five records identified through cross-referencing were assessed. Including 28 unpublished records, 125 records met the inclusion criteria. We identified 64 estimates of HIV incidence (30 from high-income countries [HICs] and 34 from low-income or middle-income countries [LMICs]) and 66 estimates of HCV incidence (52 from HICs and 14 from LMICs). 41 (64%) of 64 HIV and 42 (64%) of 66 HCV estimates were from single cities rather than being multi-city or nationwide. Estimates were measured over 1987-2021 for HIV and 1992-2021 for HCV. Pooled HIV incidence was 1·7 per 100 person-years (95% CI 1·3-2·3; I 2=98·4%) and pooled HCV incidence was 12·1 per 100 person-years (10·0-14·6; I 2=97·2%). Young PWID had a greater risk of HIV (RR 1·5, 95% CI 1·2-1·8; I 2=66·9%) and HCV (1·5, 1·3-1·8; I 2=70·6%) acquisition than older PWID. Women had a greater risk of HIV (RR 1·4, 95% CI 1·1-1·6; I 2=55·3%) and HCV (1·2, 1·1-1·3; I 2=43·3%) acquisition than men. For both HIV and HCV, the median risk-of-bias score was 6 (IQR 6-7), indicating moderate risk. INTERPRETATION: Although sparse, available HIV and HCV incidence estimates offer insights into global levels of HIV and HCV transmission among PWID. Intensified efforts are needed to keep track of the HIV and HCV epidemics among PWID and to expand access to age-appropriate and gender-appropriate prevention services that serve young PWID and women who inject drugs.FUNDING: Canadian Institutes of Health Research, Fonds de recherche du Québec-Santé, Canadian Network on Hepatitis C, UK National Institute for Health and Care Research, and WHO.</p

Incidence of HIV and hepatitis C virus among people who inject drugs, and associations with age and sex or gender: a global systematic review and meta-analysis

Background: Measuring the incidence of HIV and hepatitis C virus (HCV) infection among people who inject drugs (PWID) is key to track progress towards elimination. We aimed to summarise global data on HIV and primary HCV incidence among PWID and associations with age and sex or gender. Methods: In this systematic review and meta-analysis, we updated an existing database of HIV and HCV incidence studies among PWID by searching MEDLINE, Embase, and PsycINFO, capturing studies published between Jan 1, 2000, and Dec 12, 2022, with no language or study design restrictions. We contacted authors of identified studies for unpublished or updated data. We included studies that estimated incidence by longitudinally re-testing people at risk of infection or by using assays for recent infection. We pooled incidence and relative risk (RR; young [generally defined as ≤25 years] vs older PWID; women vs men) estimates using random-effects meta-analysis and assessed risk of bias with a modified Newcastle–Ottawa scale. This study is registered with PROSPERO, CRD42020220884. Findings: Our updated search identified 9493 publications, of which 211 were eligible for full-text review. An additional 377 full-text records from our existing database and five records identified through cross-referencing were assessed. Including 28 unpublished records, 125 records met the inclusion criteria. We identified 64 estimates of HIV incidence (30 from high-income countries [HICs] and 34 from low-income or middle-income countries [LMICs]) and 66 estimates of HCV incidence (52 from HICs and 14 from LMICs). 41 (64%) of 64 HIV and 42 (64%) of 66 HCV estimates were from single cities rather than being multi-city or nationwide. Estimates were measured over 1987–2021 for HIV and 1992–2021 for HCV. Pooled HIV incidence was 1·7 per 100 person-years (95% CI 1·3–2·3; I2=98·4%) and pooled HCV incidence was 12·1 per 100 person-years (10·0–14·6; I2=97·2%). Young PWID had a greater risk of HIV (RR 1·5, 95% CI 1·2–1·8; I2=66·9%) and HCV (1·5, 1·3–1·8; I2=70·6%) acquisition than older PWID. Women had a greater risk of HIV (RR 1·4, 95% CI 1·1–1·6; I2=55·3%) and HCV (1·2, 1·1–1·3; I2=43·3%) acquisition than men. For both HIV and HCV, the median risk-of-bias score was 6 (IQR 6–7), indicating moderate risk. Interpretation: Although sparse, available HIV and HCV incidence estimates offer insights into global levels of HIV and HCV transmission among PWID. Intensified efforts are needed to keep track of the HIV and HCV epidemics among PWID and to expand access to age-appropriate and gender-appropriate prevention services that serve young PWID and women who inject drugs. Funding: Canadian Institutes of Health Research, Fonds de recherche du Québec–Santé, Canadian Network on Hepatitis C, UK National Institute for Health and Care Research, and WHO