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Laser interaction with an ultra-thin pre-structured target is investigated with the help of both two-dimensional and three-dimensional particle-in-cell simulations. With the existence of a periodic structure on the target surface, the laser seems to penetrate through the target at its fundamental frequency even if the plasma density of the target is much higher than the laser’s relativistically critical density. The particle-in-cell simulations show that the transmitted laser energy behind the pre-structured target is increased by about two orders of magnitude compared to that behind the flat target. Theoretical analyses show that the transmitted energy behind the pre-structured target is actually re-emitted by electron ‘islands’ formed by the surface plasma waves on the target surfaces. In other words, the radiation with the fundamental frequency is actually ‘surface emission’ on the target rear surface. Besides the intensity of the component with the fundamental frequency, the intensity of the high-order harmonics behind the pre-structured target is also much enhanced compared to that behind the flat target. The enhancement of the high-order harmonics is also related to the surface plasma waves generated on the target surfaces.
In this paper we report high voltage MOS and Schottky Diode CV techniques for silicon and SiC power devices. 4H Silicon carbide is a wide bandgap semiconductor suitable for high voltage power electronics and RF applications due to high avalanche breakdown critical electric field, and thermal conductivity. The performance of various power devices, which may include MOSFET and Static Induction Transistor (SIT), can be affected by the deep level traps in the substrate and the oxide interfacial defects. We have characterized deep level trap (High Voltage Schottky Diode HF CV) and oxide interface trap densities (High Voltage HF MOS CV), measured the device channel doping profile for both 4H SiC and silicon, gate metal workfunction, and simulated the effects on DC/AC performance.
The seasonality of individual influenza subtypes/lineages and the association of influenza epidemics with meteorological factors in the tropics/subtropics have not been well understood. The impact of the 2009 H1N1 pandemic on the prevalence of seasonal influenza virus remains to be explored. Using wavelet analysis, the periodicities of A/H3N2, seasonal A/H1N1, A/H1N1pdm09, Victoria and Yamagata were identified, respectively, in Panzhihua during 2006–2015. As a subtropical city in southwestern China, Panzhihua is the first industrial city in the upper reaches of the Yangtze River. The relationship between influenza epidemics and local climatic variables was examined based on regression models. The temporal distribution of influenza subtypes/lineages during the pre-pandemic (2006–2009), pandemic (2009) and post-pandemic (2010–2015) years was described and compared. A total of 6892 respiratory specimens were collected and 737 influenza viruses were isolated. A/H3N2 showed an annual cycle with a peak in summer–autumn, while A/H1N1pdm09, Victoria and Yamagata exhibited an annual cycle with a peak in winter–spring. Regression analyses demonstrated that relative humidity was positively associated with A/H3N2 activity while negatively associated with Victoria activity. Higher prevalence of A/H1N1pdm09 and Yamagata was driven by lower absolute humidity. The role of weather conditions in regulating influenza epidemics could be complicated since the diverse viral transmission modes and mechanism. Differences in seasonality and different associations with meteorological factors by influenza subtypes/lineages should be considered in epidemiological studies in the tropics/subtropics. The development of subtype- and lineage-specific prevention and control measures is of significant importance.
Information on morbidity burden of seasonal influenza in China is limited. A multiplier model was used to estimate the incidence and number of outpatient visits for seasonal influenza by age group for the 2015–2016 season in Beijing, the capital of China, based on reported numbers of influenza-like illness consultations and proportions of positive cases from influenza surveillance systems in Beijing, general consultation rates and other parameters from previous studies, surveys and surveillance systems. An estimated total of 1 190 200 (95% confidence interval (CI) 830 400–1 549 900) cases of influenza virus infections occurred in Beijing, 2015–2016 season, with an attack rate of 5·5% (95% CI 3·9–7·2%). These infections resulted in an estimated 468 280 (95% CI 70 700–606 800) outpatient visits, with an attack rate of 2·2% (95% CI 0·3–2·8%). The attack rate of influenza virus infections was highest among children aged 0–4 years (31·9% (95% CI 21·9–41·9%)), followed by children aged 5–14 years (18·7% (95% CI 12·9–24·5%)). Our study demonstrated a substantial influenza-related morbidity in Beijing, China, especially among the preschool- and school-aged children. This suggests that development or modification of seasonal influenza targeted vaccination strategies need to recognize that incidence is highest in children.
Mycobacterial diseases are prevalent in cancer and rheumatoid arthritis (RA) patients, especially those receiving tumor necrosis factor-α inhibitor (TNFi). However, the impact of cancer development on the risk of mycobacterial diseases among RA patients is unknown. Data from the Taiwan National Health Insurance Research Database were used to conduct a retrospective study to assess the occurrence of mycobacterial diseases in RA patients developing cancer (cancer-positive), those using TNFi (TNFi-exposure), those with cancer and using TNFi (cancer-TNFi-comb), and those without cancer and not using TNFi (cancer-TNFi-free). Cancer and TNFi exposure were time-dependent, and independent risk factors of mycobacterial diseases were assessed by Cox regression. Among 1344 RA patients diagnosed during 2000–2013, 68 (5·1%) developed cancer before their end points. The incidence rates of mycobacterial diseases in the cancer-positive (n = 56), TNFi-exposure (n = 290), cancer-TNFi-comb (n = 12), and cancer-TNFi-free (n = 986) subgroups were 6·7, 2·0, 7·6, and 1·3 per 1000 person-years, respectively. As compared with the cancer-TNFi-free group, the risk for mycobacterial diseases increased for the TNFi-exposure group (adjusted HR = 3·6, 95% confidence interval (95% CI) 1·1–11·5, P = 0·032) and remained high for cancer-positive (adjusted HR = 14·6, 95% CI 3·3–63·7, P < 0·001) after adjustment. This study suggested that cancer development increased the risk of mycobacterial diseases in RA patients, and risk assessment for this subgroup should be considered.
This cross-sectional study aimed to examine and compare prevalence and correlates of whole blood Epstein–Barr virus (EBV) DNA between HIV-positive and HIV-negative men who have sex with men (MSM). Five hundred and four HIV-positive MSM and 504 age-matched HIV-negative MSM were recruited from an HIV counseling and testing clinic in Shanghai, China from November 2014 to November 2015 and were administered with a face-to-face questionnaire interview. Whole blood EBV DNA was tested by nested polymerase chain reaction assays on EBNA-1, EBNA-2, and LMP-1 genes. The prevalence of whole blood EBV DNA was 56·0% (95% CI 51·7–60·3%) among HIV-positive MSM and 26·0% (95% CI 22·4–30·0%) among HIV-negative MSM. Whole blood EBV DNA positivity was significantly associated with HIV infection (adjusted odds ratio (aOR) 3·43, 95% CI 2·58–4·57) and frequent intake of pickled, smoked, or salty food (aOR 1·71, 95% CI 1·02–2·86) in the whole sample, and with <200 cells/μl CD4 cell counts (aOR 1·79, 95% CI 1·05–3·05) and pickled, smoked, or salty food intake (aOR 3·14, 95% CI 1·39–7·08) in HIV-positive group. HIV-infected MSM are at higher risk of active EBV replication than HIV-uninfected MSM, underscoring needs of surveillance and research on EBV-related carcinogenesis in this population.
Elderly individuals with tuberculosis (TB) are more likely to have a non-specific clinical presentation of TB and high mortality. However, factors associated with mortality in elderly TB patients have not been extensively studied. This retrospective cohort study aimed to identify factors associated with death among elderly Taiwanese with TB. All elderly patients with TB from 2006 to 2014 in Taipei, Taiwan, were included in a study. Multiple logistic regression was used to identify the factors associated with death in elderly TB patients. The mean age of the 5011 patients was 79·7 years; 74·1% were men; 32·7% had mortality during the study follow-up period. After controlling for potential confounders, age ⩾75 years (reference: 65–74 years), male sex, end-stage renal disease (ESRD), malignancy, acid-fast bacilli-smear positivity, TB-culture positivity, pleural effusion on chest radiograph and notification by an ordinary ward or intensive care unit were associated with a higher risk of all-cause death; while high school, and university or higher education, cavity on chest radiograph and directly observed therapy were associated with a lower risk of all-cause death. This study found that the proportion of death among elderly patients with TB in Taipei, Taiwan, was high. To improve TB treatment outcomes, future control programmes should particularly target individuals with comorbidities (e.g. ESRD and malignancy) and those with a lower socio-economic status (e.g. not educated).
Attention deficit hyperactivity disorder (ADHD) is frequently associated with poorer reading ability; however, the specific neuropsychological domains linking this co-occurrence remain unclear. This study evaluates information-processing characteristics as possible neuropsychological links between ADHD symptoms and RA in a community-based sample of children and early adolescents with normal IQ (⩾70).
The participants (n = 1857, aged 6–15 years, 47% female) were evaluated for reading ability (reading single words aloud) and information processing [stimulus discriminability in the two-choice reaction-time task estimated using diffusion models]. ADHD symptoms were ascertained through informant (parent) report using the Development and Well-Being Assessment (DAWBA). Verbal working memory (VWM; digit span backwards), visuospatial working memory (VSWM, Corsi Blocks backwards), sex, socioeconomic status, and IQ were included as covariates.
In a moderated mediation model, stimulus discriminability mediated the effect of ADHD on reading ability. This indirect effect was moderated by age such that a larger effect was seen among younger children.
The findings support the hypothesis that ADHD and reading ability are linked among young children via a neuropsychological deficit related to stimulus discriminability. Early interventions targeting stimulus discriminability might improve symptoms of inattention/hyperactivity and reading ability.
In tritrophic ‘plants–herbivores–natural enemies’ systems, there are relatively few reports concerning the role(s) of kairomones in pupal parasitism. Chouioia cunea Yang (Hymenoptera: Eulophidae), an endoparasitic chalcid wasp, parasitizes pupae of the fall webworm (Hyphantria cunea Drury). The role of host-related kairomones was investigated using electroantennogram (EAG) and behavioral techniques. Chemicals from some host stages (pupae) and host by-products (frass), induced arrestment behavior of female parasitoids, while chemicals from prepupae, were inactive. Gas chromatography–mass spectrometry analysis of volatiles collected from pupae, frass and prepupae using solid-phase microextration revealed seven compounds with carbon chain lengths ranging from C4 to C20. All of the chemicals elicited significant EAG responses in C. cunea. Y-tube olfactometer bioassays demonstrated a significant positive response of mated female C. cunea to 1-dodecene. These data provide a better understanding of the host location mechanisms of pupal parasitoid.
In long-term care facilities (LTCFs), the elderly are apt to be infected because those with latent tuberculosis infections (LTBIs) are at an increased risk for reactivation and post-primary TB disease. We report an outbreak of TB in staff and residents in a LTCF. An outbreak investigation was conducted after two TB cases were reported from the LTCF. A tuberculin skin test (TST), bacteriological examination and chest radiograph were administered to all facility staff and residents. An outbreak is defined as at least two epidemiologically linked cases that have identical Mycobacterium tuberculosis genotype isolates. This outbreak infected eight residents and one staff member, who were confirmed to have TB in a LTCF between September 2011 and October 2012. Based on the Becker method, the latent and infectious periods were estimated at 223·6 and 55·9 days. Two initial TST-negative resident contacts were diagnosed as TB cases through comprehensive TB screening. Observing elderly people who have a negative TST after TB screening appears to be necessary, given the long latent period for controlling a TB outbreak in a LTCF. It is important to consider providing LTBI treatment for elderly contacts.
We studied the temporal and spatial patterns of leptospirosis, its association with flooding and animal census data in Thailand. Flood data from 2010 to 2012 were extracted from spatial information taken from satellite images. The incidence rate ratio (IRR) was used to determine the relationship between spatio-temporal flooding patterns and the number of human leptospirosis cases. In addition, the area of flood coverage, duration of waterlogging, time lags between flood events, and a number of potential animal reservoirs were considered in a sub-analysis. There was no significant temporal trend of leptospirosis over the study period. Statistical analysis showed an inconsistent relationship between IRR and flooding across years and regions. Spatially, leptospirosis occurred repeatedly and predominantly in northeastern Thailand. Our findings suggest that flooding is less influential in leptospirosis transmission than previously assumed. High incidence of the disease in the northeastern region is explained by the fact that agriculture and animal farming are important economic activities in this area. The periodic rise and fall of reported leptospirosis cases over time might be explained by seasonal exposure from rice farming activities performed during the rainy season when flood events often occur. We conclude that leptospirosis remains an occupational disease in Thailand.
The effect of low energy implantation of P or C ions in 3C-SiC on the properties of Ti/Ni/Au contacts has been examined for doses in the range 1013-1015 ions/cm2. Measurements of specific contact resistance, ρc, were performed using the two-contact circular test structure. The magnitude of ρc for the Ti/Ni/Au contacts on unimplanted SiC was 1.29 x 10−6 Ω.cm2. The value of ρc increased significantly at an implant dose of 1 x 1015 ions/cm2. The dependence of ρc on ion dose has been measured using both C and P implant species.
The enteric pathogens causing diarrhoea impair children's health severely. This study retrospectively analysed 1577 pathogens isolated from inpatients and outpatients in six hospitals located in Northern (Inner Mongolia), Northeastern (Hebei), Eastern (Shanghai and Jiangsu), Southern (Hainan) and Central (Hubei) China between 2008 and 2013. Of the 1577 enteric pathogens, Salmonella presented with the highest frequency (36·0%), followed by diarrhoeagenic Escherichia coli (23·7%), Staphylococcus aureus (15·0%), Shigella (13·1%), and Aeromonas (4·6%). The predominant pathogens varied in different regions of China, with Salmonella most prevalent in Shanghai and Hainan, diarrhoeagenic E. coli most prevalent in Inner Mongolia, Jiangsu and Hubei, and Shigella most prevalent in Hebei. Enteric pathogens were more frequently isolated in males (56·9%) than in females (43·1%). The highest proportion of all enteric pathogens was found in infants (67·6%) with a peak in summer and autumn (68·5%). Antimicrobial susceptibility assay demonstrated that Shigella was more resistant to ampicillin, ceftriaxone and sulfamethoxazole than Salmonella. Of the top two serotypes in Salmonella, Typhimurium was more resistant to ciprofloxacin, sulfamethoxazole and chloramphenicol than Enteritidis (P < 0·001). Meanwhile, the resistance rates of Shigella flexneri against ampicillin/sulbactam, ciprofloxacin, and chloramphenicol were significantly higher than those of Shigella sonnei (P < 0·001). Multidrug resistance was apparent in 58·2% of Shigella and 45·9% of Salmonella, and this phenomenon was more pronounced in S. flexneri.
The first human infection with avian influenza A(H7N9) virus was reported in Shanghai, China in March 2013. An additional 32 cases of human H7N9 infection were identified in the following months from March to April 2013 in Shanghai. Here we conducted a case-control study of the patients with H7N9 infection (n = 25) using controls matched by age, sex, and residence to determine risk factors for H7N9 infection. Our findings suggest that chronic disease and frequency of visiting a live poultry market (>10 times, or 1–9 times during the 2 weeks before illness onset) were likely to be significantly associated with H7N9 infection, with the odds ratios being 4·07 [95% confidence interval (CI) 1·32–12·56], 10·61 (95% CI 1·85–60·74), and 3·76 (95% CI 1·31–10·79), respectively. Effective strategies for live poultry market control should be reinforced and ongoing education of the public is warranted to promote behavioural changes that can help to eliminate direct or indirect contact with influenza A(H7N9) virus.
Recent studies of active galactic nuclei (AGN) found a statistical inverse scaling between the X-ray normalized excess variance σrms2 (variability amplitude) and the black hole mass spanning over MBH = 106 − 109M⊙. We present a study of this relation by including AGN with MBH = 105 − 106M⊙. It is found that the relation is no longer a simple extrapolation of the known inverse proportion, but starts to flatten around 106M⊙. This behavior can be understood by the shape of the power spectrum density of AGN and its dependence on the black hole mass.
Despite substantial research, uncertainty remains about the clinical and etiological heterogeneity of major depression (MD). Can meaningful and valid subtypes be identified and would they be stable cross-culturally?
Symptoms at their lifetime worst depressive episode were assessed at structured psychiatric interview in 6008 women of Han Chinese descent, age ⩾30 years, with recurrent DSM-IV MD. Latent class analysis (LCA) was performed in Mplus.
Using the nine DSM-IV MD symptomatic A criteria, the 14 disaggregated DSM-IV criteria and all independently assessed depressive symptoms (n = 27), the best LCA model identified respectively three, four and six classes. A severe and non-suicidal class was seen in all solutions, as was a mild/moderate subtype. An atypical class emerged once bidirectional neurovegetative symptoms were included. The non-suicidal class demonstrated low levels of worthlessness/guilt and hopelessness. Patterns of co-morbidity, family history, personality, environmental precipitants, recurrence and body mass index (BMI) differed meaningfully across subtypes, with the atypical class standing out as particularly distinct.
MD is a clinically complex syndrome with several detectable subtypes with distinct clinical and demographic correlates. Three subtypes were most consistently identified in our analyses: severe, atypical and non-suicidal. Severe and atypical MD have been identified in multiple prior studies in samples of European ethnicity. Our non-suicidal subtype, with low levels of guilt and hopelessness, may represent a pathoplastic variant reflecting Chinese cultural influences.
The symptoms of major depression (MD) are clinically diverse. Do they form coherent factors that might clarify the underlying nature of this important psychiatric syndrome?
Symptoms at lifetime worst depressive episode were assessed at structured psychiatric interview in 6008 women of Han Chinese descent, age ⩾30 years with recurrent DSM-IV MD. Exploratory factor analysis (EFA) and confirmatoryfactor analysis (CFA) were performed in Mplus in random split-half samples.
The preliminary EFA results were consistently supported by the findings from CFA. Analyses of the nine DSM-IV MD symptomatic A criteria revealed two factors loading on: (i) general depressive symptoms; and (ii) guilt/suicidal ideation. Examining 14 disaggregated DSM-IV criteria revealed three factors reflecting: (i) weight/appetite disturbance; (ii) general depressive symptoms; and (iii) sleep disturbance. Using all symptoms (n = 27), we identified five factors that reflected: (i) weight/appetite symptoms; (ii) general retarded depressive symptoms; (iii) atypical vegetative symptoms; (iv) suicidality/hopelessness; and (v) symptoms of agitation and anxiety.
MD is a clinically complex syndrome with several underlying correlated symptom dimensions. In addition to a general depressive symptom factor, a complete picture must include factors reflecting typical/atypical vegetative symptoms, cognitive symptoms (hopelessness/suicidal ideation), and an agitated symptom factor characterized by anxiety, guilt, helplessness and irritability. Prior cross-cultural studies, factor analyses of MD in Western populations and empirical findings in this sample showing risk factor profiles similar to those seen in Western populations suggest that our results are likely to be broadly representative of the human depressive syndrome.
As ohmic contacts decrease in size and approach nanoscale dimensions, accurate electrical characterization is essential, requiring the development of suitable test structures for this task. We present here a new test structure derived from the standard three-contact circular transmission line model (CTLM) , for determining the specific contact resistivity of ohmic contacts. This test structure minimizes sources of error which arise from the CTLM by – (i) reducing the number of contacts within one test pattern from three to two, (ii) ensuring the assumption of equipotential metal contacts used in modelling is more easily attained experimentally, and (iii) allowing the fabrication of reduced geometrical dimensions essential for determining low specific contact resistivity values. The analytical expressions are presented and experiment results are undertaken to demonstrate the accuracy of the technique. There are no error corrections required for determining contact parameters using the presented test structure.
Previous studies support Beck's cognitive model of vulnerability to depression. However, the relationship between his cognitive triad and other clinical features and risk factors among those with major depression (MD) has rarely been systematically studied.
The three key cognitive symptoms of worthlessness, hopelessness and helplessness were assessed during their lifetime worst episode in 1970 Han Chinese women with recurrent MD. Diagnostic and other risk factor information was assessed at personal interview. Odds ratios (ORs) were calculated by logistic regression.
Compared to patients who did not endorse the cognitive trio, those who did had a greater number of DSM-IV A criteria, more individual depressive symptoms, an earlier age at onset, a greater number of episodes, and were more likely to meet diagnostic criteria for melancholia, postnatal depression, dysthymia and anxiety disorders. Hopelessness was highly related to all the suicidal symptomatology, with ORs ranging from 5.92 to 6.51. Neuroticism, stressful life events (SLEs) and a protective parental rearing style were associated with these cognitive symptoms.
During the worst episode of MD in Han Chinese women, the endorsement of the cognitive trio was associated with a worse course of depression and an increased risk of suicide. Individuals with high levels of neuroticism, many SLEs and high parental protectiveness were at increased risk for these cognitive depressive symptoms. As in Western populations, symptoms of the cognitive trio appear to play a central role in the psychopathology of MD in Chinese women.