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.
Implementation scientists increasingly recognize that the process of implementation is dynamic, leading to ad hoc modifications that may challenge fidelity in protocol-driven interventions. However, limited attention to ad hoc modifications impairs investigators’ ability to develop evidence-based hypotheses about how such modifications may impact intervention effectiveness and cost. We propose a multi-method process map methodology to facilitate the systematic data collection necessary to characterize ad hoc modifications that may impact primary intervention outcomes.
We employ process maps (drawn from systems science), as well as focus groups and semi-structured interviews (drawn from social sciences) to investigate ad hoc modifications. Focus groups are conducted with the protocol’s developers and/or planners (the implementation team) to characterize the protocol “as envisioned,” while interviews conducted with frontline administrators characterize the process “as realized in practice.” Process maps with both samples are used to identify when modifications occurred across a protocol-driven intervention. A case study investigating a multistage screening protocol for autism spectrum disorders (ASD) is presented to illustrate application and utility of the multi-method process maps.
In this case study, frontline administrators reported ad hoc modifications that potentially influenced the primary study outcome (e.g., time to ASD diagnosis). Ad hoc modifications occurred to accommodate (1) whether providers and/or parents were concerned about ASD, (2) perceptions of parental readiness to discuss ASD, and (3) perceptions of family service delivery needs and priorities.
Investigation of ad hoc modifications on primary outcomes offers new opportunities to develop empirically based adaptive interventions. Routine reporting standards are critical to provide full transparency when studying ad hoc modifications.
The low-frequency polarisation properties of radio sources are poorly studied, particularly in statistical samples. However, the new generation of low-frequency telescopes, such as the Murchison Widefield Array (the precursor for the low-frequency component of the Square Kilometre Array) offers an opportunity to probe the physics of radio sources at very low radio frequencies. In this paper, we present a catalogue of linearly polarised sources detected at 216 MHz, using data from the Galactic and Extragalactic All-sky Murchison Widefield Array survey. Our catalogue covers the Declination range –17° to –37° and 24 h in Right Ascension, at a resolution of around 3 arcminutes. We detect 81 sources (including both a known pulsar and a new pulsar candidate) with linearly polarised flux densities in excess of 18 mJy across a survey area of approximately 6 400 deg2, corresponding to a surface density of 1 source per 79 deg2. The level of Faraday rotation measured for our sources is broadly consistent with those recovered at higher frequencies, with typically more than an order of magnitude improvement in the uncertainty compared to higher-frequency measurements. However, our catalogue is likely incomplete at low Faraday rotation measures, due to our practice of excluding sources in the region where instrumental leakage appears. The majority of sources exhibit significant depolarisation compared to higher frequencies; however, a small sub-sample repolarise at 216 MHz. We also discuss the polarisation properties of four nearby, large-angular-scale radio galaxies, with a particular focus on the giant radio galaxy ESO 422–G028, in order to explain the striking differences in polarised morphology between 216 MHz and 1.4 GHz.
We explore the growth of large-scale magnetic fields in a shear flow, due to helicity fluctuations with a finite correlation time, through a study of the Kraichnan–Moffatt model of zero-mean stochastic fluctuations of the
parameter of dynamo theory. We derive a linear integro-differential equation for the evolution of the large-scale magnetic field, using the first-order smoothing approximation and the Galilean invariance of the
-statistics. This enables construction of a model that is non-perturbative in the shearing rate
. After a brief review of the salient features of the exactly solvable white-noise limit, we consider the case of small but non-zero
. When the large-scale magnetic field varies slowly, the evolution is governed by a partial differential equation. We present modal solutions and conditions for the exponential growth rate of the large-scale magnetic field, whose drivers are the Kraichnan diffusivity, Moffatt drift, shear and a non-zero correlation time. Of particular interest is dynamo action when the
-fluctuations are weak; i.e. when the Kraichnan diffusivity is positive. We show that in the absence of Moffatt drift, shear does not give rise to growing solutions. But shear and Moffatt drift acting together can drive large-scale dynamo action with growth rate
Placental structure and function determine birth outcomes. Placental mass does not always correlate with fetal birth weight (BW) in uncomplicated pregnancies which raises the possibility of other variables such as placental shape and cord insertion being the determinants of placental efficiency. In total, 160 women with singleton pregnancy, recruited into a pregnancy cohort were studied. Placental weight (PW) was measured and other data were obtained from clinical records. Birth outcomes were classified as small for gestational age (SGA) and appropriate for gestational age (AGA) based on fetal gender, gestational age (GA) and BW. High-resolution images of the chorionic plate were recorded. The shape of the placenta and the insertion of the cord were measured using eccentricity index (EI) and cord centrality index (CCI). Only placentae with eccentrically inserted cords (n=136) were included. The mean BW and PW were 2942 (±435) g and 414 (±82) g with average GA of 38.6 weeks. The mean CCI and EI was 0.483 (±0.17) and 0.482 (±0.16). Neither of these correlated with placental efficiency. However, EI showed negative correlation with placental surface area and breadth. Upon sub-grouping the cohort into SGA (n=32) and AGA (n=104), the SGA babies with the highest EI (third tertile) had significantly lower BW than those with the least eccentric placentae (first tertile). Although eccentric-shaped placentae were present in both SGA and AGA groups, the effect on BW was observed only in the SGA group.
Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory disorder that affects nearly 1% of the adult population, with women being affected earlier and more often than men. The disease typically strikes between the third and sixth decades of life, but children and the elderly can be affected as well.
Despite markedly improved and more aggressive medical management, rheumatoid arthritis continues to be, for many, a progressive disease that ultimately leads to significant joint destruction, severe disability, a lower quality of life, and a shorter life expectancy.
Patients with RA typically present with complaints of
overall fatigue, morning stiffness that may improve throughout
the day, joint swelling, and pain. Patients have serology
positive for rheumatoid factor (Anti-IgG IgM antibodies) and
antibodies to cyclic citrullinated peptides (CCP) in addition
to plain radiographic findings including subchondral bony
erosions, periarticular osteopenia, and soft-tissue edema.
Synovial hypertrophy precedes joint destruction and can be
diagnosed on ultrasound or MRI. Anti-CCP antibodies can
be present and detected months to years before the autoimmune
attack on the articular surfaces. These antibodies are
positive in 50–60% of individuals with RA; antibodies may be
present in otherwise seronegative patients (negative serology
for rheumatoid factor). Clinical RA will develop in 95–98% of
patients with a positive anti-CCP antibody screen. Early diagnosis
is paramount as any delay can often lead to irreversible
joint destruction and the resultant morbidity.
Arthroscopy is the most performed procedure in orthopedics, with the knee being the most common site of surgical treatment. Advances in surgical technique and technology have led to increasing indications for knee arthroscopy. The advantages of arthroscopic surgery include the ability to function in an outpatient surgical setting, limited incisions and resultant improved cosmesis, and lowered risks for perioperative complications such as infection, substantial blood loss, and thromboembolic disease. Image capture systems and the ability to take still photographs and videos intraoperatively provide illustrations of specific pathology and procedures carried out, thereby fortifying the medical record and enhancing postoperative communication with the patient. The benefits carry over to the postoperative period in the form of lower requirements for analgesia and earlier initiation of rehabilitation protocols.
While the utility of knee arthroscopy has primarily been observed in its ability to administer therapeutic maneuvers, the arthroscope remains the gold standard as a powerful diagnostic tool. The process of preoperative counseling with the patient and obtaining informed consent is paramount, as the treatment plan can be modified based on arthroscopic findings. Surgeries performed most regularly include partial meniscectomy, meniscal repair, and anterior cruciate ligament (ACL) reconstruction. The arthroscope is also utilized for complex isolated or multiligamentous reconstructions including posterior cruciate ligament (PCL) and medial collateral ligament (MCL) work, meniscal transplantation, articular cartilage restoration, the irrigation and debridement of a pyoarthrosis, and osseous injuries such as low-energy tibial plateau fractures. A requisite for the arthroscopic management of intra-articular soft-tissue derangements is motion, as preoperative knee motion is the best predictor of postoperative motion. An exception is a locked knee joint secondary to a large bucket-handle meniscal tear.
Acquisition of the gastrointestinal microbiota at birth may have long-term health impacts. We longitudinally characterised major microbial communities in the faeces of a cohort of infants using molecular methods. Faecal samples were prospectively obtained at several time points after birth from eighty-three infants. Real-time PCR using SYBR green and primers targeted at 16S rRNA gene sequences were used to quantify Bifidobacterium, Lactobacillus acidophilus group, Bacteroides–Prevotella group, Enterobacteriaceae, Enterococcus, Clostridium coccoides–Eubacterium rectale group, Clostridium leptum group and Staphylococcus. Microbial community abundance was expressed relative to amplification of sequences conserved universally for domain bacteria. Faecal copy number of 16S rRNA genes increased non-significantly from a mean of 4·1 × 109/g on day 1 to 1·1 × 1010/g on day 4. All microbial communities were detected from day 1 after birth. Enterobacteriaceae and lactobacilli predominated on day 1, while bifidobacteria and staphylocci increased on day 4. Bacteroides–Prevotella and C. coccoides–E. rectale increased by day 180. C. leptum was detected in half of the cohort at birth and in a slightly larger percentage by 6 months. Caesarean section was associated with delayed colonisation by several bacterial communities. Higher socio-economic status was associated with more abundant lactobacilli and Bacteroides–Prevotella at 90 and 180 d. Supplemental feeding was associated with a reduction in Enterobacteriaceae. Microbial colonisation of the gut was well established on the first day of birth, and relative abundance of microbial communities was influenced by mode of delivery, socio-economic status and supplemental feeding. These findings may have relevance to infant nutrition and growth.
We study large-scale kinematic dynamo action due to turbulence in the presence of a linear shear flow in the low-conductivity limit. Our treatment is non-perturbative in the shear strength and makes systematic use of both the shearing coordinate transformation and the Galilean invariance of the linear shear flow. The velocity fluctuations are assumed to have low magnetic Reynolds number (Rem), but could have arbitrary fluid Reynolds number. The equation for the magnetic fluctuations is expanded perturbatively in the small quantity, Rem. Our principal results are as follows: (i) the magnetic fluctuations are determined to the lowest order in Rem by explicit calculation of the resistive Green's function for the linear shear flow; (ii) the mean electromotive force is then calculated and an integro-differential equation is derived for the time evolution of the mean magnetic field. In this equation, velocity fluctuations contribute to two different kinds of terms, the ‘C’ and ‘D’ terms, respectively, in which first and second spatial derivatives of the mean magnetic field, respectively, appear inside the space–time integrals; (iii) the contribution of the D term is such that its contribution to the time evolution of the cross-shear components of the mean field does not depend on any other components except itself. Therefore, to the lowest order in Rem, but to all orders in the shear strength, the D term cannot give rise to a shear-current-assisted dynamo effect; (iv) casting the integro-differential equation in Fourier space, we show that the normal modes of the theory are a set of shearing waves, labelled by their sheared wavevectors; (v) the integral kernels are expressed in terms of the velocity-spectrum tensor, which is the fundamental dynamical quantity that needs to be specified to complete the integro-differential equation description of the time evolution of the mean magnetic field; (vi) the C term couples different components of the mean magnetic field, so they can, in principle, give rise to a shear-current-type effect. We discuss the application to a slowly varying magnetic field, where it can be shown that forced non-helical velocity dynamics at low fluid Reynolds number does not result in a shear-current-assisted dynamo effect.
Aluminum Nitride (AlN) films were grown using Metal Organic Vapor Phase Epitaxy (MOVPE) techniques on Si (111) substrates patterned with SiOx stripes and the vibrational properties of these films were investigated by Fourier transform infrared (FTIR) techniques. The grown films contained a predominantly wurtzite AlN phase in addition to oxidized aluminum and mixed AlN phases. The AlN film on amorphous silicon oxide (SiOx) was prone to corrosion when subjected to wet etching in buffered hydrofluoric acid solution thereby changing the material properties of the AlN film on SiOx. The etching process significantly reduced the oxidized aluminum phase and mixed AlN phases.
This volume is the sixth in the series initiated by Cambridge University Press twenty-six years ago. The first book in the series was Language in the USA, edited by Charles A. Ferguson and Shirley Brice Heath (1981). The inspiration for the present volume on Language in South Asia came from Ferguson and Heath's pathbreaking contribution. It was the late Professor Ferguson who, in his inimitably persuasive way, suggested to one of the editors of the present volume the desirability and importance of a book on Language in South Asia. That was in the late 1970s, when Language in the USA was in the final stages of publication.
Charles A. Ferguson, affectionately called Fergi, was a committed scholar in South Asian linguistics in more than one sense. Thom Huebner, once a faculty colleague of Ferguson at Stanford University, succinctly summarizes Ferguson's “longest standing interests” in South Asia that goes back to 1945. It was then that Ferguson published his first article on South Asian linguistics. Since then, adds Huebner,
he has published nearly twenty others, he has co-edited a major volume on the topic (Ferguson and Gumperz, 1960), and there has been at least one volume of South Asian linguistics dedicated to him (Krishnamurti, 1986). In “South Asia as a Sociolinguistic Area,” Ferguson highlights some features of language use that make South Asia unique. In the process he demonstrates how features of language use just as well as language structure can cluster in real relationships. Not only does the paper deepen the reader's understanding of the region, it also suggests that this type of research into the language situation of a larger geographical region can have implications for theories of language change and cultural diffusion in general.