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 firstname.lastname@example.org
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.
The spontaneous loss of a pregnancy before the viable gestation is termed miscarriage. Miscarriage therefore includes all pregnancy losses from conception until 23 completed weeks of pregnancy. It remains the commonest adverse outcome of pregnancy and can either be sporadic or recurrent (RM). Currently, no consensus exists on the definition of RM. The Royal College of Obstetricians and Gynaecologists (RCOG) guideline defines RM as the loss of three or more consecutive pregnancies . However, the American Society for Reproductive Medicine (ASRM) has adopted the definition of consecutive loss of two or more clinical pregnancies, documented either by ultrasonography or histopathological examination . RM can be either ‘primary’ (no previous live birth) or ‘secondary’ (following a live birth).
This is a copy of the slides presented at the meeting but not formally written up for the volume.
Intrinsic stress generation during film deposition can lead to failure by processes such as cracking, delamination and peeling. Crystallite coalescence is a suggested mechanism for intrinsic tensile stress generation during film growth and various analytical models have been proposed to describe this phenomenon. In the past, researchers have not been able to measure this stress precisely because the stochastic nucleation of islands results in coalescence over a range of different times and length scales. We use a technique to control the island geometry using selective growth of films on patterned substrates. Ni films were electrodeposited on patterned Si (001) substrates using the above procedure, and in situ stress measurements were then used to study the tensile coalescence stress as a function of growth rate and island size. In these studies, most of the incremental tensile stress occurs after the initial contact of neighboring islands and the stress reaches steady state as the films planarize. With a fixed island size, increasing the growth rate causes an increase in the steady state stress, until a limiting value is reached at higher growth rates. The stress also shows some decrease with increasing island size. However, we observe a smaller grain size dependence than that predicted by previous theoretical models. To explain our results, a cohesive zone model of grain boundary formation is developed, in conjunction with a finite element analysis of the stress concentrations at the grain boundary cusps. This makes it possible to address both grain boundary phenomena and surface roughness effects.
Scholars have long puzzled over strong nationalism in weak African states. Existing theories suggest that (a) incumbent leaders use nationalistic appeals to distract people from state weakness; or (b) citizens use nationalistic claims to exclude rival groups from accessing patronage and public goods. But what explains robust nationalism in places where politicians seldom visit and where the state under-provides resources, as is true across much of Africa? We propose a theory of familial nationalism, arguing that people profess attachment to a nation-family instead of to a nation-state under conditions where the family, and not the state, is the main lifeline. We substantiate it using surveys from the border between Niger and Burkina Faso, where an international court ruling allowed people to choose their citizenship, thus providing a test for nationalism in marginalised communities. We supplement the border data with surveys and focus groups from the capitals of both countries.
Here, we report thiol-free thermal-injection synthesis of chalcopyrite (CuFeS2) nanocrystals (NCs) using iron (II) bromide (FeBr2), copper (II) acetaylacetonate (Cu(acac)2), and elemental sulfur (S). Controlled reaction temperature and growth time yield stable and phase-pure ternary CuFeS2 NCs exhibiting tetragonal crystal structure. With increasing growth time from 1 to 30 min, absorption peak slightly red shifts from 465 to 490 nm. Based on spectroscopic ellipsometry analysis, three electronic transitions at 0.652, 1.54, and 2.29 eV were found for CuFeS2 NC film. Also, CuFeS2 NC thin films are incorporated as hole transport layers in cadmium telluride solar cells reaching an efficiency of ~12%.
A stochastic production frontier approach was used to estimate input distance functions for U.S. grass-fed beef (GFB) production. Average technical efficiencies of 0.84 and 0.79 were found for U.S. GFB whole farms and enterprises, respectively. Producer education level, experience, farm size, annual net farm income from the GFB operation, annual net household income from off-farm sources, and regional differences are the efficiency drivers of U.S. GFB farms. Increasing returns to scale were found for U.S. GFB farms. Our results suggest that U.S. GFB farms can be scale efficient if the optimal size of the operation is greater than approximately 100 GFB animals.
The cadmium telluride (CdTe) photovoltaic (PV) comprise an efficient and cost-effective technology for harvesting solar energy. However, device efficiency remains limited in part by low-open circuit voltage (VOC) and fill factor (FF) due to inefficient transport of photo-generated charge carriers. Given the deep valence band of CdTe, the use of copper/gold (Cu/Au) as a back contact serves primarily to narrow the width of the inherent Schottky junction evident in CdTe solar cells (in our laboratory, Cu/Au has been used as a standard back contact). For efficient transport of carriers to and into the back contact, a hole transport layer (HTL) is desired with valence band edge comparable to that of CdTe (∼ -5.9 eV). Here, we report solution-processed nanocrystal (NCs) based thin films as HTLs in CdTe solar cells. The earth abundant materials we discuss include iron pyrite (FeS2), nickel-alloyed iron pyrite (NixFe1-xS2), zinc copper sulfide (ZnxCu1-xS) nanocomposites, and perovskite-based films. The FeS2 and NixFe1-xS2 NCs are synthesized by a hot-injection route, and thin films are fabricated by drop-casting, and spin-coating techniques using colloidal NCs. ZnxCu1-xS thin films are fabricated by chemical bath deposition. These NC-based thin films are applied and studied as the HTLs in CdTe devices. On using these materials, the device performance can be increased up to 10% compared to the standard Cu/Au back contact. Here, we discuss the benefits, challenges, and opportunities for these back contact materials in CdTe photovoltaics.
The lobate lac scale, Paratachardina pseudolobata Kondo & Gullan, is a recent insect invader to Hawaii that was first found in October 2012 on Oahu, Hawaii. It infests young branches of woody plants (usually less than 2 cm in diameter), forming a mass that appears as a dark crust, resulting in an unhealthy appearance, defoliation of leaves, and death of some plant species. This insect has infested many native and non-native plant species on Oahu, and the number of infested plant species is increasing. Our recent survey results, reported in this article, revealed 28 new host plant species in addition to 83 host species that we had reported previously, making 111 host plant species in Oahu's urban landscape. Efficacy and longevity of preventive treatment using the systemic insecticides imidacloprid and emamectin benzoate, delivered through trunk injection, against lobate lac scale on Chinese banyan, Ficus microcarpa, and curative treatment using imidacloprid on weeping banyan, Ficus benjamina, were evaluated. Forty-five Chinese banyans and 10 weeping banyans were included in this study. Our findings suggest that imidacloprid delivered via trunk injection is effective in preventing lobate lac scale infestation for at least 22 months post-treatment, and also in reducing lobate lac scale infestation curatively for at least 20 months post-treatment. This study provides an update on lobate lac scale's host species in Hawaii's urban landscape, and an effective preventive and curative management strategy against this pest.
The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
The class of radio transients called Fast Radio Bursts (FRBs) encompasses enigmatic single pulses, each unique in its own way, hindering a consensus for their origin. The key to demystifying FRBs lies in discovering many of them in order to identity commonalities – and in real time, in order to find potential counterparts at other wavelengths. The recently upgraded UTMOST in Australia, is undergoing a backend transformation to rise as a fast transient detection machine. The first interferometric detections of FRBs with UTMOST, place their origin beyond the near-field region of the telescope thus ruling out local sources of interference as a possible origin. We have localised these bursts to much better than the ones discovered at the Parkes radio telescope and have plans to upgrade UTMOST to be capable of much better localisation still.
A large number of elements in certain meteorites have isotopic composition different from that existing in rocks of the earth or the moon. Excess amounts of some isotopes, which are radiogenic daughters, are attributed to the in situ decay of their parent nuclide. Material containing radioactive parents is believed to have been injected into the condensing solar nebula, from astrophysical sites of their production shortly before formation of these grains. Other isotopic anomalies do not show mass dependent pattern which is characteristic of chemical fractionation. They must be primary isotopic abundances, if it is assumed that physico-chemical processes in the solar nebula cannot produce non-mass dependent fractionation. In such a case the observed isotopic ratios characterise elements differently synthesised and injected into the solar nebula which condensed before it had enough time to homogenise. Thus the isotopically anomalous matter has extra solar origin and may contain supernovae condensates, interstellar matter or dust from other stars. The evidence for different isotopic anomalies is briefly summarised and discussed in terms of the current ideas regarding chemical processes occurring in the early solar system.
Multielemental analysis of chondrules from unequilibrated E3 chondrite Parsa show that the lithophile elements, both refractory and volatile, are enriched and siderophiles are depleted relative to C1 abundances. This behaviour is generally similar to chondrules from unequilibrated ordinary chondrites (UOC). A detailed comparison of compositional trends in chondrules from E3 chondrites (Parsa and Quingzhen) with UOC's indicates that some of the precursor components of chondrules of E3's are different from those of UOC's.
Introduction: Emergency medicine physicians in our urban/suburban area have a range of training in medical education; some have no formal training in medical education, whereas others have completed Master’s level training in adult education. Not all staff have a university appointment; of those who are affiliated with our university, 87 have appointments through the Department of Medicine, 21 through the Department of Pediatrics, and 117 through the Department of Family Medicine. Emergency physicians in our area are a diverse group of physicians in terms of both formal training in adult education and in the variety of settings in which we work. The purpose of this study was to gauge interest in formal training in adult education among emergency medicine physicians. Methods: With research ethics board approval, we created and sent a 10-item electronic questionnaire to emergency medicine staff in our area. The questionnaire included items on demographics, experience in emergency medicine, additional post-graduate training, current teaching activities and interest in short (30-60 minute) adult education sessions. Results: Of a potential 360 active emergency physicians in our area, 120 responded to the questionnaire (33.3%), representing 12 area hospitals. Nearly half of respondents had been in practice over 10 years (48.44%). Respondents were mainly FRCP (50%) or CCFP-EM (47.50%) trained. 33.3% of respondents had masters degrees, of which 15% were MEd. Most physicians were involved in teaching medical students (98.33%), FRCP residents (80%) and family medicine residents (88.3%), though many were also teaching off-service residents, and allied health professionals. More than half of respondents (60%) were interested in attending short sessions to improve their skills as adult educators. The topics of most interest were feedback and evaluation, time-efficient teaching, the learner in difficulty, case-based teaching and bedside teaching. Conclusion: Emergency physicians in our area have a wide variety of experience and training in medical education. They are involved in teaching learners from a range of training levels and backgrounds. Physicians who responded to our survey expressed an interest in additional formal teaching on adult education topics geared toward emergency medicine.
Surface and core samples of Neh–nar Glacier in the Kashmir Valley have been analysed for the radionuclides 32Si. 210Pb, 40K, and 137Cs. The lateral and vertical profiles (at an altitude of about 4 140 m) reveal:
(1)32Si activity decreasing slowly from the accumulation zone to 4 050 m altitude and then abruptly towards the snout.
(2)Five zones of alternating high and low 210Pb activity in the surface samples.
(3)An horizon at between 2 and 3 m depth containing 210Pb activity above natural levels. This horizon is also associated with 137Cs and a maximum in total ß activity.
The ice samples have been dated on the basis of a simplified two–component model, the “fresh“contribution determined by 2l0Pb and the old component by 32Si. The following conclusions can be drawn from these observations:
(1)The model age of the snout ice is c. 850 years.
(2)The average rate of ice movement in the lower glacier is about 2 m/year, which compares well with the annual movement rate of 2.65 m/year observed since 1974.
The 32Si concentration in a sample of surface ice from the snout of Changme-Khangpu glacier is 0.36 disintegrations per minute/tonne compared to the fall-out value of 0.7 d.p.m./tonne. If this decrease is assumed to be solely due to decay of 32Si, an age off c. 100 years is estimated for the surface ice of the snout, leading to an average flow velocity of c. 40 m/year for the past century. A vertical profile of 210Pb in a core taken at an altitude of 5040 m shows two horizons where this isotope is enriched, one between 3 and 4 m and another between 11 and 12 m, indicating that the primary concentration of 210Pb can change by physico-chemical processes like adsorption on dust. None the less, a longitudinal profile along the glacier shows a systematic decrease of 210Pb activity with decreasing altitude, the surface ice of the snout giving a value of 0.2 d.p.m./l, corresponding to an age of 100 years which is concordant with the 32Si age. This surface flow-rate of the glacier is much larger than the average contemporary flow-rate (c. 13m/year). The difference can be understood in terms of the past history of advance and recession of the glacier as revealed by the geomorphic evidence.
We have measured 14C, 210Pb and 137Cs profiles in two representative cores from Manasbal Lake, Kashmir, India. The sedimentation rate derived from 210Pb and 137Cs in the upper part of the core is in the range of 3.4 to 5.5 mm yr−1. In contrast, 14C ages show an inversion at depths >20 cm. These results are attributed to the erosion of the ubiquitous 10–20-m-thick loess mantle, based on the similarity of 14C ages of the inversion layer in the sediments and the paleosols present in the catchment area. Frequency-dependent mineral magnetic susceptibility (χfd), carbon to nitrogen ratios and pigment concentrations in the profile show a significant amount of allochthonous component in the lake deposits and support the conclusion that the 14C dates do not reflect the chronology of the in-situ lake sedimentation but episodic deposition of the surrounding loess. Thus, 14C serves as a useful tracer to understand source components of the sediments.
The response of a pair of differently polarized antennas is determined by their polarization states and a phase between them which has a geometric part which becomes discontinuous at singular points in the parameter space. Some consequences are described.
Introduction: Regional anesthesia has been shown to be an effective pain control strategy for patients presenting with hip fractures in the emergency department. There are two common methods for performing this block: the femoral nerve block (FNB) and the fascia iliaca compartment block (FICB). The objective of this pilot study is to determine whether one of these two ultrasound-guided block techniques provides superior analgesia to emergency department patients with hip fractures. Methods: Emergency physicians at a single institution were randomized to the FNB or FICB training groups. Participants completed a 2-hour practical workshop covering the technique, followed by a questionnaire to assess their comfort with the block. They were asked to perform their assigned nerve block on any patient in the ED presenting with a hip or femur fracture. Physician comfort level and patient pain scores using a visual analog scale (VAS) were recorded before and after the nerve block were recorded. Comparisons were performed using Student’s t-test and Fisher’s exact test. Results: A total of 20 physicians were enrolled in the study, 10 in the FNB group and 10 in the FICB group. There were no significant baseline differences between the groups with respect to ultrasound or nerve block experience. Following the training, 100% of participants in both the FNB group and FICB group felt comfortable performing the block. Nerve blocks were performed in 30/51 (58.8%) of eligible patients in the FNB group and 6/11 (54.5%) in the FICB group (p=1.0). On the 10-point VAS, pain scores decreased by a mean of 4.9 (SD 3.5) in the FNB group and 8.3 (SD 2.4) in the FICB group (p=0.056). In practice, physicians felt comfortable performing the FNB in 52.8% of cases, and the FICB in 85.7% of cases (p=0.21). Mean time to completion of the blocks was similar between the two groups (19 vs 18 mins, p=0.83). Conclusion: In this pilot study, we found a non-significant trend towards improved analgesia and higher physician comfort with the ultrasound-guided FICB compared with the FNB in patients with hip fractures. We found no differences in time to performing the blocks. These results require confirmation with a larger sample size.
Introduction: Ultrasound-guided femoral nerve block (USFNB) is optimal for providing analgesia for patients with hip fractures, but is rarely performed. Time of the procedure was cited as a barrier in our previous survey. Methods: We conducted a knowledge-to-practice intervention that included a two-hour training session on USFNB, use of a block kit, and reminders to improve uptake of USFNB. We measured the time it took for trained EPs to complete the block during a 20 month period. Results: Of 36 EPs, 34 (94.4%) were not routinely performing USFNB at the beginning of the study, and 4 declined to participate, leaving 30 participants who received training. The 30 trained EPs performed 100 USFNB over the next 20 months (range 1 to 20 blocks per EP). The mean reduction in pain was -4.47 on a 10 point numeric rating scale. The median time to perform the blocks was 15.0 minutes (IQR, 10 to 20 minutes), and 90 % of blocks took less than 30 minutes. The most common reason given for not performing a block was excessive clinical load. Conclusion: Given that we included 88.2% of eligible EP’s and included the first time EP’s performed a USFNB, our estimates of time to perform USFNB block should generalize to other Canadian academic ED’s. Time to complete USFNB is in keeping with other commonly performed ED procedures and should not be a barrier to optimizing analgesia.
Study of a model data analysis situation with the help of computer experiments reveals that the Maximum Entropy Method of Spectral Analysis owes its popularity to a peak-sharpening property which is found to be a strong function of the level of background white noise present in the spectrum. In one limit, misleading results may be obtained by this technique. Some suggestions for a more fruitful use of the technique are made.