To send 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 sending content to .
To send 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 sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent 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.
In this perspective, the authors challenge the status quo of polymer innovation. The authors first explore how research in polymer design is conducted today, which is both time consuming and unable to capture the multi-scale complexities of polymers. The authors discuss strategies that could be employed in bringing together machine learning, data curation, high-throughput experimentation, and simulations, to build a system that can accurately predict polymer properties from their descriptors and enable inverse design that is capable of designing polymers based on desired properties.
High power superfluorescent fiber sources (SFSs), which could find wide applications in many fields such as middle infrared laser generation, Raman fiber laser pumping and spectral beam combination, have experienced a flourishing time in recent years for its unique properties, such as short coherence length and high temporal stability. The challenge for performance scalability of powerful SFS mainly lies on the physical issues including parasitic laser oscillation and modal instability (MI). In this contribution, by employing in-band pumping avenue and high-order transverse-mode management, we explore a high power SFS with record power, near-diffraction-limited beam quality and spectral manipulation flexibility. An ultimate output power of 3.14 kW can be obtained with high temporal stability and a beam quality of
for the amplified light. Furthermore, the dynamics of spectral evolutions, including red-shifting of central wavelength and unsymmetrical broadening in spectral wings, of the main amplifier with different seed linewidths are investigated contrastively. Benefiting from the unique high pump brightness and high MI threshold of in-band pumping scheme, the demonstrated system also manifests promising performance scaling potential.
In this paper, we experimentally investigated the extreme frequency shift in high-power Raman fiber laser (RFL). The RFL was developed by using a pair of fiber Bragg gratings with fixed and matched central wavelength (1120 nm) combined with a piece of 31-m-long polarization maintaining (PM) passive fiber adopted as Raman gain medium. The pump source was a homemade high-power, linearly polarized (LP) wavelength-tunable master oscillator power amplifier (MOPA) source with
tunable working range (1055–1080 nm). High-power and high-efficiency RFL with extreme frequency shift between the pump and Stokes light was explored. It is found that frequency shift located within 10.6 THz and 15.2 THz can ensure efficient Raman lasing, where the conversion efficiency is more than 95% of the maximal value, 71.3%. In addition, a maximum output power of 147.1 W was obtained with an optical efficiency of 71.3%, which is the highest power ever reported in LP RFLs to the best of our knowledge.
In the past few years, we have performed a 22 GHz H2O maser survey towards hundreds of BGPS sources using the 25-meter Nanshan Radio Telescope (NSRT) of the Xinjiang Astronomical Observatory, and detected more than one hundred masers. Our aim is to study star formation activities associated with these sources, as well as search for any correlations that may exist between 22 GHz H2O masers and the evolutionary stage of high-mass star formation regions. The NSRT has been upgraded and have now an effective diameter of 26 meter. Besides, cryogenically cooled dual-beam receiver systems covering seven millimeter-wave observing bands have been installed on the NSRT. For the next step of maser observation, we will continue to do H2O and SiO masers survey of massive dust clumps and monitor some maser sources.
Babesiosis is an emerging tick-transmitted zoonosis prevalent in large parts of the world. This study was designed to determine the rates of Babesia microti infection among small rodents in Yunnan province, where human cases of babesiosis have been reported. Currently, distribution of Babesia in its endemic regions is largely unknown. In this study, we cataloged 1672 small wild rodents, comprising 4 orders, from nine areas in western Yunnan province between 2009 and 2011. Babesia microti DNA was detected by polymerase chain reaction in 4·3% (72/1672) of the rodents analyzed. The most frequently infected rodent species included Apodemus chevrieri and Niviventer fulvescens. Rodents from forests and shrublands had significantly higher Babesia infection rates. Genetic comparisons revealed that Babesia was most similar to the Kobe- and Otsu-type strains identified in Japan. A variety of rodent species might be involved in the enzootic maintenance and transmission of B. microti, supporting the need for further serological investigations in humans.
The acquisition and tracking strategies of the BeiDou navigation satellite signals are affected by the modulation of Neumann-Hoffman code (NH code), which increases the complexity of receiver baseband signal processing. Based on the analysis of probability statistics of the NH code, a special sequence of incoming signals is proposed to evade the bit transitions caused by the NH code, and an NH Code Evasion and Stripping method (NCES) based on the NH-pre-modulated code is proposed. The NCES can be applied in both 20-bit NH code and 10-bit NH code. The fine acquisition eliminates the impact of NH code on the traditional tracking loop. These methods were verified with a BeiDou PC-based software-defined receiver using the actual sampled signals. Compared with other acquisition schemes which try to determine or ignore the NH code phase, the NCES needs fewer incoming signals and the actual runtime is greatly reduced without sacrificing much time to search in the secondary code dimension, and the success rate of acquisition is effectively improved. An extension of Fast Fourier Transform (FFT)-based parallel code-phase search acquisition gives the NCES an advantage in engineering applications.
We present results of a regional comparative study of surface mass changes from 2004 to 2008 based on Gravity Recovery and Climate Experiment (GRACE), The Ice, Cloud and Land Elevation Satellite (ICESat) and CHINARE observations over the Lambert Glacier/Amery Ice Shelf system (LAS). Estimation of the ICESat mass change rates benefitted from the density measurements along the CHINARE traverse and a spatial density adjustment method for reducing the effect of spatial density variations. In the high-elevation inland region, a positive trend was estimated from both ICESat and GRACE data, which is in line with the CHINARE accumulation measurements. In the coastal region, there were areas with high level accumulations in both ICESat and GRACE trend maps. In many high flow-speed glacier areas, negative mass change rates may be caused by dynamic ice flow discharges that have surpassed the snow accumulation. Overall, the mass change rate estimate in the LAS of 2004–2008 from the GRACE, ICESat and CHINARE data is 5.41 ± 4.59 Gt a−1, indicating a balanced to slightly positive mass trend. Along with other published results, this suggests that a longer-term positive mass trend in the LAS may have slowed in recent years.
The objective of this study was to determine the protective effect of glutamate (Glu) in Cu-induced oxidative injury in fish intestine in vivo and enterocytes in vitro. The results indicated that exposure to 6 mg/l Cu for 72 h induced the production of reactive oxygen species, thereby increasing protein oxidation and lipid peroxidation in enterocytes of grass carp in vitro. Cells exposed to Cu alone resulted in a significant increase in lactate dehydrogenase release, which is accompanied by depletions of antioxidants, including total superoxide dismutase (T-SOD), glutathione S-transferase (GST), glutathione reductase (GR), anti-superoxide anion (ASA), anti-hydroxy radical (AHR) activities and GSH content. Pre-treatment with Glu remarkably prevented the toxic effects of Cu on the T-SOD, GST, GR, AHR, and ASA activities and GSH content in enterocytes. However, Cu induced an adaptive increase in the activities of catalase and glutathione peroxidase (GPx). Glu supplementation further increased GPx activity in enterocytes. Interestingly, the experiment in vivo showed that Glu pre-supplementation significantly elevated SOD, GPx, GST, GR, ASA and AHR activities, as well as GSH content. Further results showed that pre-treatment with Glu could alleviate Cu-induced oxidative injury by elevating antioxidant enzyme activities through regulating the expression of NF-E2-related nuclear factor 2 (Nrf2) mRNA. Together, these results indicated that Glu could attenuate Cu-induced cellular oxidative damage in fish intestine, likely mediated through Nrf2 signalling pathways regulating mRNA expressions of antioxidant enzyme genes and synthesis of GSH.
The present study evaluated the effects of dietary microbial phytase on the growth and gut health of hybrid tilapia (Oreochromis niloticus ♀×Oreochromis aureus ♂), focusing on the effect on intestinal histology, adhesive microbiota and expression of immune-related cytokine genes. Tilapia were fed either control diet or diet supplemented with microbial phytase (1000 U/kg). Each diet was randomly assigned to four groups of fish reared in cages (3×3×2 m). After 12 weeks of feeding, weight gain and feed conversion ratio of tilapia were not significantly improved by dietary microbial phytase supplementation. However, significantly higher level of P content in the scales, tighter and more regular intestinal mucosa folds were observed in the microbial phytase group and the microvilli density was significantly increased. The adhesive gut bacterial communities were strikingly altered by microbial phytase supplementation (0·41<similarity coefficient<0·54). Stimulated intestinal inflammation and stress status were observed in the fish fed diet supplemented with microbial phytase, as indicated by the up-regulated intestinal expressions of the cytokine genes (tnf-α and tgf-β) and hsp70. In addition, the gut microvilli height was significantly decreased in the phytase group. These results indicate that dietary microbial phytase may exert mixed effects on hybrid tilapia, and can guide our future selection of phytases as aquafeed additives – that is, eliminating those that can stimulate intestinal inflammation.
As one of the tip-based top-down nanoscale machining methods, atomic force microscopy (AFM) electric lithography is capable of directly generating flexible nanostructures on conductive or semi-conductive sample surfaces. In this work, distinct fabrication mechanisms and mechanism transition from local anodic oxidation (LAO) to electrical breakdown (BD) in the AFM nanoscale electric lithography of the highly oriented pyrolytic graphite sample surface was studied. We provide direct evidence of the transition process mechanism through the detected current–voltage (I–V) curve. Characteristics of the fabrication results under the LAO, transition, and BD regions involving the oxide growth rate or material removal rate and AFM probe wear are analyzed in detail. These factors are of great significance for improving the machining controllability and expanding its potential applications.
The present study was conducted to investigate the anti-inflammatory effect of vitamin D both in juvenile Jian carp (Cyprinus carpio var. Jian) in vivo and in enterocytes in vitro. In primary enterocytes, exposure to 10 mg lipopolysaccharide (LPS)/l increased lactate dehydrogenase activity in the culture medium (P<0·05) and resulted in a significant loss of cell viability (P<0·05). LPS exposure increased (P<0·05) the mRNA expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-8), which was decreased by pre-treatment with 1,25-dihydroxyvitamin D (1,25D3) in a dose-dependent manner (P<0·05). Further results showed that pre-treatment with 1,25D3 down-regulated Toll-like receptor 4 (TLR4), myeloid differentiation primary response gene 88 (Myd88) and NF-κB p65 mRNA expression (P<0·05), suggesting potential mechanisms against LPS-induced inflammatory response. In vivo, intraperitoneal injection of LPS significantly increased TNF-α, IL-1β, IL-6 and IL-8 mRNA expression in the intestine of carp (P<0·05). Pre-treatment of fish with vitamin D3 protected the fish intestine from the LPS-induced increase of TNF-α, IL-1β, IL-6 and IL-8 mainly by downregulating TLR4, Myd88 and NF-κB p65 mRNA expression (P<0·05). These observations suggest that vitamin D could inhibit LPS-induced inflammatory response in juvenile Jian carp in vivo and in enterocytes in vitro. The anti-inflammatory effect of vitamin D is mediated at least in part by TLR4-Myd88 signalling pathways in the intestine and enterocytes of juvenile Jian carp.
From November 24 to December 10, 2013, the Chinese People’s Liberation Army Navy [PLA(N)] hospital ship Peace Ark was deployed to the Leyte Gulf in the Philippines to provide humanitarian medical relief in Tacloban after Typhoon Haiyan. The purpose of this study was to assess the radiological services aboard the ship to provide guidance for future missions.
A retrospective review was performed on a cohort of 109 patients who underwent digital radiography (DR) and 59 patients who underwent computed tomography (CT) scans during a 16-day period during a humanitarian medical relief mission to the Philippines. Patient demographics, DR findings, and CT findings were analyzed.
The mean age of the 109 DR patients was 39.7 years for the 64 males and 43.7 years for the 45 females. A total of 148 DR examinations were performed of the chest (n=109), extremities (n=35), and spine (n=4). The mean age of the 59 CT patients was 43.8 years for the 32 males and 49.1 years for the 27 females. A total of 72 CT scans were performed of the head and neck (n=36), thorax (n=24), abdomen (n=5), spine (n=4), and extremities (n=3). The imaging findings mainly included disaster-related and non-disaster-related fractures, pulmonary tuberculosis, pulmonary infection, acute brain infarction, intracranial hematoma, and occupying lesions.
Analysis of radiological services during a humanitarian medical relief mission to the Philippines provided meaningful information for future humanitarian medical relief missions. (Disaster Med Public Health Preparedness. 2016;10:16–19)
In the present study, twenty-four Duroc × Landrance × Yorkshire (initial body weight (BW) of 21·82 (sem 2·06) kg) cross-bred pigs were used to determine whether dietary vitamin D supplementation could confer protection against viral infections through the retinoic acid-inducible gene I (RIG-I) signalling pathway in pigs. Experimental treatments were arranged in a 2 × 2 factorial manner with the main effects of immune challenge (control v. porcine rotavirus (PRV) challenge) and dietary concentrations of vitamin D (200 and 5000 IU; where 1 IU of vitamin D is defined as the biological activity of 0.025 mg of cholecalciferol). The pigs were fed a diet containing 200 or 5000 IU vitamin D in the first week of the study period. On day 8, the pigs were orally dosed with 4 ml of Dulbecco's modified Eagle's medium/Ham's F-12 medium containing PRV or essential medium (control). Serum samples were collected on day 8 (pre-challenge), and 6 d after the PRV challenge, the pigs were killed to evaluate intestinal morphology and tissue gene expression following the last blood collection. Pigs challenged with PRV had decreased BW gain (P< 0·01), feed intake (P< 0·01), villus height (P< 0·01), faecal consistency (P< 0·05), and serum 1,25-dihydroxyvitamin D concentration (P< 0·01) and increased (P< 0·01) serum IL-2, IL-6 and interferon (IFN)-β concentrations. Vitamin D supplementation mitigated these effects. The mRNA expression of RIG-I (P< 0·01), IFN-β promoter stimulator 1 (P< 0·01), IFN-β (P< 0·01) and interferon-stimulated gene 15 (ISG15) (P< 0·01) was up-regulated by the PRV challenge and vitamin D supplementation in the intestine. In conclusion, vitamin D supplementation could activate the RIG-I signalling pathway and thus alleviate the negative effects caused by PRV challenge.
A joint diagnostic system was established for the diagnosis of laser-driven shock wave experiments. The system has high temporal resolution (time resolution ~12 ps) and high spatial resolution (spatial resolution ~7 μm) and fits for diagnostics of the experiment with small sample size and short time physical process. The joint diagnostic system was applied for shock wave measurement on the Shenguang-II laser facility. The passive shock breakout signal and active diagnostic signal were simultaneously obtained. The temporal measurement reliability of the system was verified using a multi-layered target. The experimental results show that the two measurement results were consistent.
Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.
Two sets of reciprocal introgression lines (ILs) and a population of recombinant inbred lines (RILs) derived from the cross between japonica cultivar Xiushui09 and indica breeding line IR2061-520-6-9 (abbreviated as IR2061) were used to identify QTL for heading date (HD). Phenotyping was conducted in Hainan Island for two winter seasons (2007 and 2009). Nine QTLs were detected in the ILs with Xiushui09 background (XS-ILs), and four of which were repeatedly mapped across 2 years. Five QTLs were identified in the ILs with IR2061 background (IR-ILs), and three of which were commonly detected in 2 years. All commonly detected QTL had the same direction of gene effect. Seven QTL for HD were identified in the RILs in 2009. Only three (25%) QTLs were commonly detected using all the three populations (XS-ILs, IR-ILs and RILs). The number of commonly identified QTLs among populations was related to degree of similarity of their genetic backgrounds, suggesting that the genetic background effect is important for detecting HD QTL. QHd7 and QHd10b stably expressed in different populations and across years thus would be exploited in rice breeding programme. Moreover, lines with both of QHd7 and QHd10b resulted in at least 3 days earlier than lines with only one of them QTL, showing evident pyramiding effect.
Optical cavities are extremely useful devices in laser-based research. Within the context of precision measurement, they enable tests of the laws that govern the macroscopic structure of the universe, embodied in the search for gravitational waves (Abbott and The LIGO Scientific Collaboration, 2009) (see also Chapter 14). At the other end of the length scale, cavity-stabilized lasers are powerful tools for precision spectroscopy that probe nature at the quantum mechanical level, through tests of quantum electrodynamics (QED) (Kolachevsky et al., 2009). Furthermore, cavities enable high-sensitivity broadband spectroscopy (Thorpe et al., 2006), which has practical applications in trace gas sensing; exploration of new light – matter interaction regimes in cavity QED (Miller et al., 2005) (see also Chapter 17); tests of fundamental physical principles including relativity (Brillet and Hall, 1979; Hils and Hall, 1990; Eisele et al., 2009), local position invariance (Blatt et al., 2008), and the time invariance of the fundamental constants of nature (Fortier et al., 2007b); and nonlinear optics, including coherent light build-up for studies of extremely nonlinear effects (Gohle et al., 2005; Yost et al., 2009). In general, optical cavities have become indispensable tools at the heart of many modern experiments.
In conjunction with optical frequency combs, cavity-stabilized laser systems have enabled the development of highly accurate frequency standards based on neutral atoms (Sterr et al., 2004; Takamoto et al., 2005; Ludlow et al., 2006; Le Targat et al., 2006; Ludlow et al., 2008; Lemke et al., 2009) and trapped ions (Diddams et al., 2001; Madej et al., 2004; Margolis et al., 2004; Rosenband et al., 2008).
Gd silicide nanostructures epitaxially grown on Si(001) are studied by plan-view transmission electron microscopy and associated nanobeam electron diffraction, as well as scanning tunneling microscopy. The nanobeam diffraction measurements show a direct correlation between the nanostructure morphology, either nanowires or islands, and the silicide crystal structure. Scanning tunneling microscopy shows a phase transformation from nanowires to islands that nucleate at nanowire intersections. A specific mechanism for this transformation is proposed that explains nanowire growth behavior previously observed on vicinal Si surfaces.
State-of-the-art ICs for microprocessors routinely dissipate power densities
on the order of 50 W/cm2. This large power is due to the
localized heating of ICs operating at high frequencies, and must be managed
for future high-frequency microelectronic applications. Our approach
involves finding new and efficient thermally conductive materials.
Exploiting carbon nanotube (CNT) films and composites for their superior
axial thermal conductance properties has the potential for such an
application requiring efficient heat transfer. In this work, we present
thermal contact resistance measurement results for CNT and CNT-Cu composite
films. It is shown that Cu-filled CNT arrays enhance thermal conductance
when compared to as-grown CNT arrays. Furthermore, the CNT-Cu composite
material provides a mechanically robust alternative to current IC packaging