To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement simultaneously. The results show that the Stokes linewidth behavior in a free-space-running Brillouin laser cavity is determined by the phase diffusion of the pump and the technical noise of the system. Experimentally, a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%, which is nearly 2.5 times compressed compared with the linewidth of the pump (7.36 kHz). In addition, the theorical analysis shows that at a pump power of 60 W and a coupling mirror reflectivity of 96%, a Stokes output with a linewidth of 1.6 kHz and up to 80% optical conversion efficiency can be achieved by reducing the insertion loss of the intracavity. This study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.
We report the experimental results of the commissioning phase in the 10 PW laser beamline of the Shanghai Superintense Ultrafast Laser Facility (SULF). The peak power reaches 2.4 PW on target without the last amplifying during the experiment. The laser energy of 72 ± 9 J is directed to a focal spot of approximately 6 μm diameter (full width at half maximum) in 30 fs pulse duration, yielding a focused peak intensity around 2.0 × 1021 W/cm2. The first laser-proton acceleration experiment is performed using plain copper and plastic targets. High-energy proton beams with maximum cut-off energy up to 62.5 MeV are achieved using copper foils at the optimum target thickness of 4 μm via target normal sheath acceleration. For plastic targets of tens of nanometers thick, the proton cut-off energy is approximately 20 MeV, showing ring-like or filamented density distributions. These experimental results reflect the capabilities of the SULF-10 PW beamline, for example, both ultrahigh intensity and relatively good beam contrast. Further optimization for these key parameters is underway, where peak laser intensities of 1022–1023 W/cm2 are anticipated to support various experiments on extreme field physics.
The spatio-temporal variation of leaf chlorophyll content is an important crop phenotypic trait that is of great significance for evaluating crop productivity. This study used a soil-plant analysis development (SPAD) chlorophyll meter for non-destructive monitoring of leaf chlorophyll dynamics to characterize the patterns of spatio-temporal variation in the nutritional status of maize (Zea mays L.) leaves under three nitrogen treatments in two cultivars. The results showed that nitrogen levels could affect the maximum leaf SPAD reading (SPADmax) and the duration of high SPAD reading. A rational model was used to measure the changes in SPAD readings over time in single leaves. This model was suitable for predicting the dynamics of the nutrient status for each leaf position under different nitrogen treatments, and model parameter values were position dependent. SPADmax at each leaf decreased with the reduction of nitrogen supply. Leaves at different positions in both cultivars responded differently to higher nitrogen rates. Lower leaves (8th–10th positions) were more sensitive than the other leaves in response to nitrogen. Monitoring the SPAD reading dynamic of lower leaves could accurately characterize and assess the nitrogen supply in plants. The lower leaves in nitrogen-deficient plants had a shorter duration of high SPAD readings compared to nitrogen-sufficient plants; this physiological mechanism should be studied further. In summary, the spatio-temporal variation of plant nitrogen status in maize was analysed to determine critical leaf positions for potentially assisting in the identification of appropriate agronomic management practices, such as the adjustment of nitrogen rates in late fertilization.
The characteristic traits of maize (Zea mays L.) leaves affect light interception and photosynthesis. Measurement or estimation of individual leaf area has been described using discontinuous equations or bell-shaped functions. However, new maize hybrids show different canopy architecture, such as leaf angle in modern maize which is more upright and ear leaf and adjacent leaves which are longer than older hybrids. The original equations and their parameters, which have been used for older maize hybrids and grown at low plant densities, will not accurately represent modern hybrids. Therefore, the aim of this paper was to develop a new empirical equation that captures vertical leaf distribution. To characterize the vertical leaf profile, we conducted a field experiment in Jilin province, Northeast China from 2015 to 2018. Our new equation for the vertical distribution of leaf profile describes leaf length, width or leaf area as a function of leaf rank, using parameters for the maximum value for leaf length, width or area, the leaf rank at which the maximum value is obtained, and the width of the curve. It thus involves one parameter less than the previously used equations. By analysing the characteristics of this new equation, we identified four key leaf ranks (4, 8, 14 and 20) for which leaf parameter values need to be quantified in order to have a good estimation of leaf length, width and area. Together, the method of leaf area estimation proposed here adds versatility for use in modern maize hybrids and simplifies the field measurements by using the four key leaf ranks to estimate vertical leaf distribution in maize canopy instead of all leaf ranks.
Previous studies have revealed associations of meteorological factors with tuberculosis (TB) cases. However, few studies have examined their lag effects on TB cases. This study was aimed to analyse nonlinear lag effects of meteorological factors on the number of TB notifications in Hong Kong. Using a 22-year consecutive surveillance data in Hong Kong, we examined the association of monthly average temperature and relative humidity with temporal dynamics of the monthly number of TB notifications using a distributed lag nonlinear models combined with a Poisson regression. The relative risks (RRs) of TB notifications were >1.15 as monthly average temperatures were between 16.3 and 17.3 °C at lagged 13–15 months, reaching the peak risk of 1.18 (95% confidence interval (CI) 1.02–1.35) when it was 16.8 °C at lagged 14 months. The RRs of TB notifications were >1.05 as relative humidities of 60.0–63.6% at lagged 9–11 months expanded to 68.0–71.0% at lagged 12–17 months, reaching the highest risk of 1.06 (95% CI 1.01–1.11) when it was 69.0% at lagged 13 months. The nonlinear and delayed effects of average temperature and relative humidity on TB epidemic were identified, which may provide a practical reference for improving the TB warning system.
Previous studies have shown that African American youth are over-represented in the Criminal Justice System (CJS). Substance use problems are common among those with CJS involvement. However, less is known regarding racial disparities, among youth with CJS involvement, in receiving substance use treatment services.
To examine racial disparities with regard to receiving treatment services for substance use related problems, among youth with (CJS) involvement.
Data were obtained from the 2006–2008 United States National Survey on Drug Use and Health (NSDUH) in USA. Among White and African American adolescents (Ages 12–17) with recent CJS involvement and who met criteria for alcohol or illicit drug abuse or dependence (N = 602), racial differences in receiving treatment services for substance use problems were examined. Multiple logistic regression analyses were performed to identify predictors of service access among the adolescents, to see if the racial disparity could be explained by individual-level, family-level, and criminal justice system involvement factors.
While 31.2% of White adolescent substance abusers with CJS involvement had received treatment for substance use related problems, only 11.6% of their African American counterparts had received such treatment (P = 0.0005). Multiple logistic regression analyses showed that access to treatment services can be predicted by substance use related delinquent behaviors, but that racial disparities in treatment still exist after adjusting for these factors (AOR = 0.24, 95%CI = (0.09,0.59), P = 0.0027).
There is an urgent need to reduce racial disparities in receiving substance use treatment among U.S. youth with CJS involvement.
Several questions still exist in the literature on the relationship between cumulative exposure to work-related incidents and posttraumatic stress disorder (PTSD) in First Responders (FR).
To address three unanswered questions in the field.
(1) Are different cumulative exposure scoring algorithms similarly related to PTSD?
(2) Is PTSD associated only with incidents rated as severe and traumatic?
(3) Can we identify cut-off scores of cumulative exposure that maximize sensitivity and specificity to predict PTSD?
To better characterize the relationship between cumulative exposure and PTSD in FR.
The association between exposure and PTSD was examined with logistic and linear regression and with receiver operating characteristic analysis in 349 FR.
(1) The strength of the association between PTSD and total cumulative exposure indexes varied across different scoring algorithms.
(2) Compared to total cumulative exposure indexes and to sub-scores of exposure to non-traumatic and/or less severe incidents, sub-scores indexing exposure to severe traumatic events only were more strongly and significantly associated with PTSD.
(3) The use of two cut-off scores maximizes sensitivity and specificity to predict PTSD.
(1) The relationship between current PTSD and cumulative exposure is partially dependent on the approach used to quantify exposure.
(2) Focusing on the assessment of cumulative exposure to severe traumatic events is sufficient to predict PTSD, and might be more useful and effective in research and clinical decision-making.
(3) Sensitivity and specificity of exposure scores might help improve secondary prevention (early detection and effective intervention) of individuals at risk.
The heterogeneity in the manifestation of PSTD symptomatology has never been described in a developmental period spanning from middle childhood through adolescence. The examination of developmental influences on PTSD symptomatic expression is a high priority for DSM-V and could inform research on the etiology and treatment of PTSD.
To examine the symptom structure of PTSD across different age, gender, and exposure groups, and in association with impairment and other disorders.
To identify homogeneous latent classes of PTSD symptoms in children and adolescents.
Latent class analysis (LCA) was applied to 6,733 New York City students (4th–12th grades) exposed to 9/11-related potentially traumatic events. LCA was first applied to PTSD symptoms only, stratified by age, gender and empirically defined exposure groups, and then in combination with impairment indicators. The resultant classes were studied in association with other disorders.
LCA identified 4 classes that vary in severity and symptom configuration. Only the most severe profile, qualitatively characterized by the presence of traumatic memories in combination with avoidance and sleep-related problems, showed high levels of impairment and high rates of other disorders. Girls after puberty and subjects indirectly exposed to 9/11 are at increased risk of severe disturbance.
The 4-class model describes quantitative and qualitative differences in the structure of PTSD across age, gender and exposure. These findings support the inclusion of developmental considerations into DSM-V PTSD diagnostic criteria and suggest that also gender and the nature of traumatic exposure inflence PTSD phenomenology in children and adolescents.
Tuberculosis (TB) is generally considered a disease that principally afflicts the low-income segments of a population. In the Nanshan District of Shenzhen, China, with the economic transformation and a new Headquarters Economy (HE) emerging, there are now more cases in office workers than in manufacturing workers. To illustrate this trend, we describe a small TB outbreak in an office building located in the centre of the rapidly growing HE district. Two active pulmonary tuberculosis cases were found in workers who shared an office, and whole genome sequencing showed that the genetic distance between the strains of the two cases was just one single nucleotide polymorphism, consistent with intra-office transmission. Investigation of 30 other workers in the same or adjacent offices with interviews, interferon-gamma release assays (IGRAs) and chest X-rays, identified one new TB case and latent tuberculosis infection (LTBI) in 40.0% (12/30) of the contacts. The offices were under-ventilated. None of the IGRA positive, asymptomatic contacts agreed to receive treatment for LTBI, presumably due to TB stigma, and over the next 2 years 69.0% (20/29) of the contacts were lost to follow-up. Treatment for LTBI and stigma of TB remain challenges here. Office workers in the HE of rapidly economic developing areas should be targeted with increased vigilance by TB control programmes.
Enteric pathogens have been related to child undernutrition. Whereas there are lots of data on enteric bacterial microbiota and infections, much less is known about the incidence of prevalence of intestinal colonisation with viruses or important parasitic species. This study assessed the presence of selected viruses and parasites in stools of 469, 354, 468 Malawian children at 6, 12 and 18 months. We also assessed environmental predictors of the presence of viruses and parasites among 6-month infants. Microbial presence was documented using real-time polymerase chain reaction (PCR). Enteroviruses were identified in 68%, 80% and 81% of the stool samples at 6, 12 and 18 months children, rhinovirus in 28%, 18% and 31%, norovirus in 24%, 22% and 16%, parechovirus in 23%, 17% and 17%, rotavirus in 3%, 1% and 0.6%, Giardia lamblia in 9.6%, 23.5% and 26%, and Cryptosporidium (spp.) in 6%, 8% and 2% of the 6, 12 and 18 months stool samples. Dry season (May–October) was associated with a low infection rate of enterovirus, norovirus and Cryptosporidium (spp.). Higher father's education level, less number of person in the household and higher sanitation were associated with a low infection rate of enterovirus, norovirus and rotavirus, respectively. The results suggest that the prevalence of asymptomatic viral and parasitic infections is high among Malawian children and that the family's living conditions and seasonality influence the rate of infections.
Covering a broad optical spectrum, ternary InxGa1−xAs nanowires, grown by bottom-up methods, have been receiving increasing attention due to the tunability of the bandgap via In composition modulation. However, inadequate knowledge about the correlation between growth and properties restricts our ability to take advantage of this phenomenon for optoelectronic applications. Here, three different InGaAs nanowires were grown under different experimental conditions and atom probe tomography was used to quantify their composition, allowing the direct observation of the nanowire composition associated with the different growth conditions.
OBJECTIVES/SPECIFIC AIMS: Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice, and has widely varying treatments for stroke prevention and rhythm management. Some of these therapies are increasingly being prescribed by primary care physicians (PCPs). We therefore sought to investigate if healthcare plans with PCP gatekeeping for access to specialists are associated with different pharmacologic treatment strategies for the disease. In particular, we focused on oral anticoagulants (OACs), non-vitamin K-dependent oral anticoagulants (NOACs), rate control, and rhythm control medications. METHODS/STUDY POPULATION: We examined a commercial pharmaceutical claims database (Truven Marketscan™) to compare the prescription frequency of OAC, rate control, and rhythm control medications used to treat AF between patients with PCP-gated health plans (where the PCP is the gatekeeper to specialist referral—i.e., HMO, EPO, POS) and patients with non-PCP-gatekeeper health plans (i.e., comprehensive, PPO, CHDP, HDHP). To control for potential confounders, we also used multivariable logistic regression models to calculate adjusted odds ratios which accounted for age, sex, region, Charlson comorbidity index, CHADS2Vasc score, hypertension, diabetes, stroke/transient ischemic attack, prior myocardial infarction, peripheral artery disease, and antiplatelet medication use. We also calculated median time to therapy to determine if there was a difference in time to new prescription of these medications. RESULTS/ANTICIPATED RESULTS: We found only small differences between patients in PCP-gated and non-PCP-gated plans regarding prescription proportion of anticoagulants at 90 days following new AF diagnosis (OAC 44.2% vs. 42%, p<0.01; warfarin 39.1% vs. 37.1%, p<0.01; NOAC 5.9% vs. 6.0%, p=0.64). We observed similar trends for rate control agents (76.4% vs. 73.4%, p<0.01) and rhythm control agents (24.4% vs. 24.6%, p=0.83). We found similar odds of OAC prescription at 90 days following new AF diagnosis between patients in PCP-gated and non-PCP-gated plans (adjusted OR for PCP-gated plans relative to non-gated plans: OAC 1.006, p=0.84; warfarin 1.054, p=0.08; NOAC 0.815, p=0.001; dabigatran 0.833, p=0.004; and rivaroxaban 0.181, p=0.02). We observed similar trends for rate control agents (1.166, p<0.0001) and rhythm control agents (0.927, p=0.03). Elapsed time until receipt of medication was similar between PCP-gated and non-gated groups [OAC 4±14 days (interquartile range) vs. 5±16 days, p<0.0001; warfarin 4±14 vs. 5±14, p<0.0001; NOAC 7±26 vs. 6±23, p=0.2937; rhythm control 13±35 vs. 13±34, p=0.8661; rate control 10±25 vs. 11±30, p<0.0001]. DISCUSSION/SIGNIFICANCE OF IMPACT: We found that plans with PCP gatekeeping to specialist referrals were not associated with clinically meaningful differences in prescription rates or delays in time to prescription of oral anticoagulation, rate control, and rhythm control drug therapy. In some cases, PCP gatekeeping plans had very small but statistically significant lower odds of being prescribed NOACs. These findings suggest that PCP gatekeeping does not appear to be a major structural barrier in receipt of medications for AF, although non-PCP-gated plans may vary slightly favor facilitating the prescription of NOACs. Our findings that overall OAC prescriptions did not differ by PCP gating status may suggest completion of the rapid dissemination and uptake phase for most AF treatments. The small but statistically significant odds ratios favoring the non-PCP-gated populations in NOACs further suggests that in this newer drug group, the process is ongoing, with more specialists representing early adopters. Interestingly, the low primary care odds ratio of rivaroxaban use, relative to dabigatran, may be indicative of a gradient of uptake of later-generation NOACs, although interpretability is limited by the small number of patients in the rivaroxaban group.
Graphene possesses exceptional mechanical, electrical, and thermal properties that stand out for numerous applications in materials and energy-related areas. The growing demand to produce high-quality large-scale graphene films inexpensively remains a challenge. The work presented in this paper emphasizes a straightforward method of producing high-quality graphene films using cellulose as the starting materials. We demonstrate the synthesis of defect-free graphene films (as thin as ∼10 layers) on substrates up to 7 cm2 in area. Graphitic films were characterized using Infrared Raman, energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD), scanning electron microcopy SEM, and high-resolution transmission electron microscopy (HRTEM). Our XRD, Raman, and HRTEM studies indicated that the synthetic temperature was critical in the synthesis of high-quality graphene films using cellulose as the carbon source material. Systematic studies revealed that defect-free large area graphitic films were produced at a synthetic temperature of ∼900 °C. The Raman D band peak intensity decreased for the samples synthesized at higher temperature but was absent for the samples prepared at 900 °C. Both the HRTEM and selected area electron diffraction confirm the highly ordered arrangement of carbon atoms in the sample matrix. The measured distance between lattice fringes was 0.335 nm, which matches with the literature reported fringe distance for the high-quality graphene. The XRD spectrum of the thin graphitic samples synthesized at 900 °C displayed a sharp diffraction peak 2θ–26.5° characteristic of highly crystalline defect-free graphene. Functional photodetector and photovoltaic (PV) devices were fabricated using graphitic films. The graphitic films were used as one of the electrodes for the PV devices yielded a power conversion efficiency of ∼1%. Our synthetic method can be potentially used for producing high-quality free-standing graphene films inexpensively at large-scale.
This study was designed to explore the association between undernutrition in the growth period and cardiovascular risk factors in a middle-aged Chinese population. A total of 1756 subjects, aged 45–60 years, were invited to participate in the Hefei Nutrition and Health Study and divided into three groups according to their self-reported animal food intake in the growth period. Group 1, Group 2 and Group 3 were defined as undernutrition, nutritional improvement and the good nutrition group, respectively. In the three groups, the subjects in Groups 1 and 2 had more oil and salt intake (P<0.001), and less eggs and milk intake (P<0.001), when compared with the subjects in Group 3. After adjusting for age, education, smoking status and other confounding factors, it was found that male participants who experienced nutritional improvement before age 18 had higher risk of hypertension [odds ratio (OR)=1.68; 95% confidence intervals (CI): 1.05, 2.69] than those with good nutrition, and female participants with undernutrition (OR=1.52; 95% CI: 1.01, 2.29) and nutritional improvement (OR=1.68; 95% CI: 1.04, 2.69) before age 18 had a higher risk of hypertension than those with good nutrition. For diabetes, obesity, hypercholesterolemia and hypertriglyceridemia, our results did not found difference among the three groups both in male and female. Our findings indicated that nutritional deficiency in childhood was associated with bad dietary behaviors and a significantly increased risk of hypertension in middle age. Therefore, early adequate nutrition is very important for the prevention of non-communicable diseases later.
The study investigated whether different dietary energy and protein sources affect laying performance, antioxidant status, fresh yolk fatty acid profile and quality of salted yolks in laying ducks. In all, 360 19-week-old Longyan ducks were randomly assigned to four diets in a factorial arrangement (2×2). The four diets consisted of two energy sources, corn (CO) or sorghum (SO) and two protein sources, soybean meal (SM) and rapeseed meal with corn distillers dried grains with solubles (RMD), and each treatment contained six replicates of 15 birds each. The experimental diets were isocaloric (metabolizable energy, 10.84 MJ/kg) and isonitrogenous (CP, 17%). The results showed that egg production, average egg weight, egg mass and feed conversion ratio were not affected by diets (P>0.05). Plasma contents of reduced glutathione (GSH), GSH/oxidized glutathione and total antioxidant capacity were lower (P<0.05) in ducks fed the RMD diets compared with those fed SM diets with a substantial increase (P=0.006) in plasma content of malondialdehyde (MDA). Egg yolks from ducks fed SO diets had higher proportions of polyunsaturated fatty acids (PUFA) and lower saturated and monounsaturated fatty acids compared with CO diets (P<0.001). Similarly, ducks fed RMD diets had a higher content of PUFA and n-6/n-3 ratio in fresh yolks (P<0.001), and increased salted yolk MDA, carbonylated proteins content and incidence of hard salted yolks (P<0.05) compared with SM diets. Scanning electron microscopy showed that salted yolks contained rougher polyhedral granules and fewer fat droplets, and were surrounded with a layer of bunchy fibers in ducks fed SO+RMD than those fed CO+SM diet. In conclusion, the current study showed that feeding laying ducks with diets containing SO or RMD reduced antioxidant capacity and increased egg yolk concentrations of PUFA. It appeared that egg yolks from ducks fed these diets were more sensitive to lipid peroxidation and protein oxidation during salting, and reduced the quality of salted yolks.
The mammalian target of rapamycin (mTOR) has been shown to be involved in lipopolysaccharide (LPS)-induced immune responses in many mammal cells. Here, we suggest that the mTOR pathway is involved in the intestinal inflammatory responses evoked by LPS treatment in chicken embryos. The intestinal tissue from Specific pathogen free chick embryos was cultured in the presence of LPS for 2 h. Secretory immunoglobulin A (sIgA) concentrations, messenger RNA (mRNA) expression of cytokines, and protein levels of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), mTOR and p70 ribosomal S6 kinase (p70S6K) were determined. The results showed that LPS treatment increased sIgA concentrations in a dose-dependent manner. The mRNA levels of interleukine (IL)-6, IL-8, IL-10, tumor necrosis factor-α and Toll-like receptor (TLR) 4 were upregulated by LPS treatment (P<0.05). Lipopolysaccharide increased the phosphorylation of Jun N-terminal kinase (JNK), p38 MAPK and NF-κB (P<0.05) while decreasing the phosphorylation level of mTOR (P<0.05). Supplementation of leucine at doses of 10, 20 and 40 mM dose-dependently decreased sIgA production. Leucine supplementation at 40 mM restored the phosphorylation level of mTOR and p70S6K while suppressing the phosphorylation levels of NF-κB (P<0.05) and partially down-regulating the phosphorylation of p38 MAPK and JNK. The transcription of IL-6 was significantly decreased by leucine supplementation. These results suggested that leucine could alleviate LPS-induced inflammatory responses by down-regulating NF-κB signaling pathway and evoking mTOR/p70S6K signaling pathway, which may involve in the regulation of the intestinal immune system in chicken embryos.
Cell membrane fatty acids influence fundamental properties of the plasma membrane, including membrane fluidity, protein functionality, and lipid raft signalling. Evidence suggests that dietary n-3 PUFA may target the plasma membrane of immune cells by altering plasma membrane lipid dynamics, thereby regulating the attenuation of immune cell activation and suppression of inflammation. As lipid-based immunotherapy might be a promising new clinical strategy for the treatment of inflammatory disorders, we conducted in vitro and in vivo experiments to examine the effects of n-3 PUFA on CD4+ T cell membrane order, mitochondrial bioenergetics and lymphoproliferation. n-3 PUFA were incorporated into human primary CD4+ T cells phospholipids in vitro in a dose-dependent manner, resulting in a reduction in whole cell membrane order, oxidative phosphorylation and proliferation. At higher doses, n-3 PUFA induced unique phase separation in T cell-derived giant plasma membrane vesicles. Similarly, in a short-term human pilot study, supplementation of fish oil (4 g n-3 PUFA/d) for 6 weeks in healthy subjects significantly elevated EPA (20 : 5n-3) levels in CD4+ T cell membrane phospholipids, and reduced membrane lipid order. These results demonstrate that the dynamic reshaping of human CD4+ T cell plasma membrane organisation by n-3 PUFA may modulate down-stream clonal expansion.