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.
Sustainable commercial use of native wildlife is an alternative economic means of land use by Indigenous people in remote rural areas. This situation applies within large tracts of land owned by Indigenous people across northern Australia. The commercial use of saltwater crocodiles Crocodylus porosus is a growing industry in Australia's Northern Territory. Although Indigenous people sell crocodile eggs and hatchlings, the majority of harvesting and incubation is done by non-indigenous people from less remote areas. One Indigenous community has been heavily involved in this industry and now manages its own harvest and incubation programme. We present a case study of this programme, which has transitioned from outside agencies managing the harvest, to complete local ownership and management. Egg harvests and incubation success rates declined by 40% following the switch to local management. Income increased, as did production costs; in particular, royalty payments made to Indigenous landowners. The declines reflect the community's motives for engaging in the industry, which have been socially rather than commercially driven, and damage to nesting habitat by feral animals. The increase in royalties reflects the need to compete with non-indigenous harvesters from outside the township, who are strictly commercially driven. Harvesting, incubation and trade in crocodile eggs and hatchlings can form a viable and sustainable enterprise for remote Indigenous communities. However, efficiency needs to be improved to fulfil the need for a reliable and dependable supply chain, and regulatory institutions should give Indigenous harvesters sufficient freedom to pursue innovative and viable livelihood options.
The present research aimed to investigate the efficacy of a multifaceted intervention that included motivational interviewing (MI) and psychoeducation in improving medication adherence (MA) among patients with bipolar disorder (BD).
A multicenter, cluster randomized, observer-blind, controlled, parallel-group trial was conducted in ten academic centers in Iran. Patients with BD were randomly assigned to the experimental group (EXP; n = 136) or the usual care group (UC; n = 134). The EXP group received five sessions of MI and psychoeducation together with their family members. The primary outcome measure was changes in scores on the Medication Adherence Rating Scale from baseline to 6 months post-intervention. Other outcome measures included serum levels of mood stabilizers, clinical symptoms, quality of life, as well as measures of intention, beliefs about medicine, perceived behavioral control, automaticity, action and coping planning, and adverse reactions.
Medication adherence improved over time in both groups, but patients in the EXP group improved more (baseline score: 6.03; score at the sixth month: 9.55) than patients in the UC group (baseline score: 6.17; score at the sixth month: 6.67). In addition, patients in the EXP group showed greater improvement than patients in the UC group in almost all secondary outcomes 6 months following the intervention.
Multifaceted interventions that include motivational-interviewing and psychoeducation can significantly improve MA and clinical and functional outcomes in patients with BD.
The large and optically clear embryos of the zebrafish provide an excellent model system in which to study the dynamic assembly of the essential contractile band components, actin and myosin, via double fluorescent labelling in combination with confocal microscopy. We report the rapid appearance (i.e. within <2 min) of a restricted arc of F-actin patches along the prospective furrow plane in a central, apical region of the blastodisc cortex. These patches then fused with each other end-to-end forming multiple actin cables, which were subsequently bundled together forming an F-actin band. During this initial assembly phase, the F-actin-based structure did not elongate laterally, but was still restricted to an arc extending ~15° either side of the blastodisc apex. This initial assembly phase was then followed by an extension phase, where additional F-actin patches were added to each end of the original arc, thus extending it out to the edges of the blastodisc. The dynamics of phosphorylated myosin light chain 2 (MLC2) recruitment to this F-actin scaffold also reflect the two-phase nature of the contractile apparatus assembly. MLC2 was not associated with the initial F-actin arc, but MLC2 clusters were recruited and assembled into the extending ends of the band. We propose that the MLC2-free central region of the contractile apparatus acts to position and then extend the cleavage furrow in the correct plane, while the actomyosin ends alone generate the force required for furrow ingression. This biphasic assembly strategy may be required to successfully divide the early cells of large embryos.
In this paper, we have carried out the positron annihilation measurement on high-rate and low-rate a-Si:H thin films deposited by PECVD. By means of the slow positron beam Doppler-broadening technique, the depth profiles of microvoids in a-Si:H have been determined. We have also studied the vacancy-type defect in the surface region in high-rate grown a-Si:H, making comparison between high-rate and low-rate a-Si:H. By plotting S and W parameters in the (S, W) plane, we have shown that the vacancies in all of the high-rate and low-rate deposited intrinsic samples, and in differently doped low-rate samples are of the same nature.
Recent experimental developments have cast doubt on the validity of the common assumption that the distribution of tail states of hydrogenated amorphous silicon exhibits a single exponential functional form. We employ transient photocurrent decay measurements to determine this distribution of tail states. In our approach, however, we determine the distribution of tail states directly from the experimental data, without assuming, a priori, a specific functional form. It is found that these experimental results are consistent with other more recent experimental determinations of the distribution of tail states, suggesting the possibility of deviations from a single exponential distribution of tail states in hydrogenated amorphous silicon.
The fabrication and characterization of AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOSHFETs) with the δ-doped barrier are reported. The incorporation of the SiO2 insulated-gate and the δ-doped barrier into HFET structures reduces the gate leakage and improves the 2D channel carrier mobility. The device has a high drain-current-driving and gate-control capabilities as well as a very high gate-drain breakdown voltage of 200 V, a cutoff frequency of 15 GHz and a maximum frequency of oscillation of 34 GHz for a gate length of 1 μm. These characteristics indicate a great potential of this structure for high-power-microwave applications.
AlGaN/GaN two dimensional electron gas (2DEG) heterostructures were grown by ammonia-MBE on sapphire and SiC substrates. Devices fabricated from these optimized HFET layers, with optically defined gates showed excellent characteristics, e.g. a maximum drain current density of 1.3 A/mm, maximum transconductance of 220 mS/mm, fT of 15.6 GHz and fMAX of 58.1 GHz was measured for devices with 0.9 μm gate length and 40 μm gate width. Shorter gate length devices exhibited higher frequency responses: fT of 68 GHz and fMAX of 125 GHz for 0.25 μm gate length and fT of 103 GHz and fMAX of 170 GHz for 0.15 μm gate length. However, these devices showed “current collapse” when subjected to load pull measurements. Current collapse was also observed in sequentially repeated DC measurements in the dark, both on sapphire and SiC substrates, although the degree of collapse varied greatly from one wafer to another. One method of reducing the current collapse was to apply a thin (100 - 6000 Å) magnetron sputtered AlN passivation layer (over the gates) or a 500 Å layer under the gates so that MISFET devices were obtained. The electrical characteristics of the passivated and unpassivated devices are discussed.
This paper describes an approach for assessing the geosphere performance of nuclear waste disposal in fractured rock. In this approach, a three-dimensional heterogeneous channelnetwork model is constructed using a stochastic discrete fracture network (DFN) code. Radionuclide migration in the channel-network model is solved using the Laplace transform Galerkin finite element method, taking into account advection-dispersion in a fracture network, matrix diffusion, sorption in the rock matrix as well as radioactive chain decay. Preliminary radionuclide migration analysis was performed for fifty realizations of a synthetic block-scale DFN model. The total radionuclide release from all packages in the repository was estimated from the statistics of the results of fifty realizations under the hypothesis of ergodicity. The interpretation of the result of the three-dimensional network model by a combination of simpler one-dimensional parallel plate models is also discussed.
Some of the key parameters used in process simulators are formation energy, diffusivity and the concentration of Si self-interstitials. Unfortunately, experimental verification of these parameters is lacking. This work is therefore designed to determine the equilibrium concentration of self-interstitials at various temperatures and thus compute the formation energy for selfinterstitials in Si. Samples with thin (10 nm) buried boron layers were grown by MBE and samples with a buried type II dislocation loop layer were produced by Ge+ implantation into undoped MBE. These samples were subjected to a 40 KeV 1E14 /cm2 Si+ implant followed by anneals at temperatures between 685°C and 815°C for varying times. The loop layer was investigated to monitor the total flux of the interstitials as a function of time while the broadening of the B layer profile was analyzed by SIMS to determine the interstitial supersaturation. A combination of these two values provides an estimate of the equilibrium concentration of the Si interstitials. The results at various temperatures are then used to extract the enthalpy of formation of the Si interstitial.
Research into electro-optic effects in nanophase polymer dispersed liquid crystal (PDLC) materials has highlighted their potential as materials for a new class of tuneable filters. The structures, based on UV cured phase separated composites, contain liquid crystal both as discrete nano-scale droplets, and as material dissolved in the polymeric host. The essential difference between these materials and more conventional PDLC's is the scale of the refractive index inhomogeneity which is considerably smaller than the wavelength of visible light. Based upon effective medium approximations, the composite thus acts as a single isotropic medium, whose average refractive index is dependant on the level of applied electric field. Tuneable filters have been fabricated using the composite material for use in the visible spectral band.
The growth of reactively sputtered TiNx and WNx compound metal films on ultra-thin, remote plasma enhanced chemical vapor deposited SiO2 and SiO2/Si3N4 (ON) stack dielectrics is investigated from initial interface formation to bulk film by interrupted growth and on-line Auger electron spectroscopy (AES). Growth of both metals occurs uniformly without a seed layer on both dielectrics. The chemical stability of these metal/dielectric interfaces is studied by sequential on-line rapid thermal annealing treatments up to 850 °C and AES. TiNx reacts with SiO2 above 850 °C but the addition of a Si3N4 dielectric top-layer makes the TiNx/ON interface chemically stable at 850 °C. WNx/SiO2 and WNx/Si3N4 interfaces are both stable below 650 °C. MOS capacitors using TiNx or WNx metal gates and thermal SiO2 gate dielectrics exhibit excellent capacitance-voltage characteristics. The work function for TiNx lies near midgap in Si while for WNx it lies closer to the valence band.
This paper describes ultra shallow junction formation using 0.5 keV B+/BF2+ implantation, which has the advantage of a reduced channeling tail and no transient enhanced diffusion. In the case of l × 1014 cm−2, 0.5 keV BF2 implantation a junction depth of 19 nm is achieved after RTA at 950°C.
We show how positron annihilation can distinguish vacancies in undoped hydrogenated amorphous silicon by performing Variable Energy Positron Annihilation Spectroscopy experiments before and after light soaking. We find that vacancy clusters, di-vacancies and a new type of single vacancies are created in undoped as-grown a-Si:H thin film by light illumination. The fact that the vacancy clusters are eliminated by the thermal annealing suggests that the Staebler-Wronski effect is closely related to vacancy clusters in a-Si:H material. The creation of vacancy clusters and redistribution of di-vacancies and even single vacancies probably result in photo-induced structural changes in this material.
By means of the slow positron beam Doppler-broadening technique, the depth profile of microvoids across a p-i-n double junction solar cell has been resolved. VEPFIT fitting results indicate an approximately uniform density of the defects throughout the solar cell, but with an enhanced concentration at all of the interfaces possibly due to network mismatch. In order to evaluate the internal electric field, Variable Energy Positron Annihilation Spectroscopy (VEPAS) measurements have been performed on a single junction pin solar cell at different biases. The internal electric field effect on positrons has also been examined in terms of the bias dependence of positron drift in a-Si:H single junction pin solar cell.
Crystalline quality of locally oxidized silicon wafers has been studied. Wafers from different supply sources were found to be differently susceptible to stress-induced dislocation generation, although they had been produced to the same specification. On the basis of the analysis of a depth distribution of the dislocations, critical resolved shear stress of dislocation movement in the bulk areas of the wafers was determined. It varied from about 1.65 to 5.12 MPa and correlated positively to the surface defect density. The results show that uncontrollable variations of bulk silicon properties may significantly influence the stress-induced defect nucleation on the surface of wafers during processing.
Early studies of the novel swine-origin 2009 influenza A (H1N1) epidemic indicate
clinical attack rates in children much higher than in adults. Non-medical interventions
such as school closings are constrained by their large socio-economic costs. Here we
develop a mathematical model to ascertain the roles of pre-symptomatic influenza
transmission as well as symptoms surveillance of children to assess the utility of school
closures. Our model analysis indicates that school closings are advisable when
pre-symptomatic transmission is significant or when removal of symptomatic children is
inefficient. Our objective is to provide a rational basis for school closings decisions
dependent on virulence characteristics and local surveillance implementation, applicable
to the current epidemic and future epidemics.
This study investigated the adaptive gait pattern in obstacle clearance in 12 normally developing (ND) children (six males, six females; mean age 10y 2mo, SD 10mo) and 12 children who had spastic diplegic cerebral palsy (CP) and who were independent ambulators (10 males, two females; mean age 13y 5mo, SD 2y 7mo). Children in both groups had 8 to 12 years of walking experience. They walked up to and crossed over obstacles of a height of 0%, 10%, and 20% of their leg length. Kinematic aspects of the three-dimensional leg movements were captured with the Vicon system and analyzed with one-way analysis of variance with repeated measure. Both groups increased foot clearance for higher obstacles. Children with CP were slower in approach and crossing speed, and used a wider base of support than the ND children when the obstacle height was increased. Results suggest that motor problems in obstacle clearance in children with CP lie in the implicit process of motor control, i.e. torque dynamics, not the explicit process, i.e. movement-match with the environmental constraints.
A new approach, the propagating-source method, is introduced to
solve the time-dependent Boltzmann equation. The method relies on the
decomposition of the particle distribution function into scattered and
unscattered particles. It is assumed in this paper that the particles are
transported in a constant-velocity spherically expanding supersonic flow (such
as the solar wind) in the presence of a radial magnetic field. Attention too has
been restricted to very fast particles. The present paper addresses only large-angle scattering, which is modelled as a BGK relaxation time operator. A
subsequent paper (Part 2) will apply the propagating-source method to a small-angle quasilinear scattering operator. Initially, we consider the simplest form of
the BGK Boltzmann equation, which omits both adiabatic deceleration and
focusing, to re-derive the well-known telegrapher equation for particle
transport. However, the derivation based on the propagating-source method
yields an inhomogeneous form of the telegrapher equation; a form for which
the well-known problem of coherent pulse solutions is absent. Furthermore, the
inhomogeneous telegrapher equation is valid for times t much smaller than the
‘scattering time’ τ, i.e. for times t [Lt ] τ, as
well as for t > τ. More complicated
forms of the BGK Boltzmann equation that now include focusing and adiabatic
deceleration are solved. The basic results to emerge from this new approach to
solving the BGK Boltzmann equation are the following. (i) Low-order
polynomial expansions can be used to investigate particle propagation and
transport at arbitrarily small times in a scattering medium. (ii) The theory of
characteristics for linear hyperbolic equations illuminates the role of causality
in the expanded integro-differential Fokker–Planck equation. (iii) The
propagating-source approach is not restricted to isotropic initial data, but
instead arbitrarily anisotropic initial data can be investigated. Examples using
different ring-beam distributions are presented. (iv) Finally, the numerical
scheme can include both small-angle and large-angle particle scattering
operators (Part 2). A detailed discussion of the results for the various
Boltzmann-equation models is given. In general, it is found that particle beams
that experience scattering by, for example, interplanetary fluctuations are
likely to remain highly anisotropic for many scattering times. This makes the
use of the diffusion approximation for charged-particle transport particularly
dangerous under many reasonable solar-wind conditions, especially in the inner
In this paper, positron annihilation measurements have been carried out on a-Si: H thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) at high and low rates by means of the variable energy positron beam Doppler-broadening technique. The depth profiles of microvoids in the films grown under different conditions have been determined. We found a smaller void fraction in the surface region of all films compared to the bulk, and a smaller void fraction in low rate than in high growth rate films. By plotting S and W parameters in the (S, W) plane, we have shown that the vacancies in all of the high-rate and low-rate deposited intrinsic samples, and in differently doped low-rate samples are of the same nature, although there appears to be a higher density of defects in the boron than phosphorus doped films. The depth profiles of the microvoid-like defects in the a-Si: H films are extracted by use of the vepfit program.