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.
The main aim of the present studies is to determine whether, or to some extent, specific cognitive domains could differentiate the main subtypes of mood disorder in the depressed and clinically remitted status respectively.
Three groups of bipolar I (n = 92), bipolar II (n = 131) and unipolar depression patients (n = 293) were tested with a battery of neuropsychological tests at baseline and after 6 weeks of treatment, contrasting with 202 healthy controls on cognitive performance.
At the acute depressive state, the three patients groups (bipolar I, bipolar II and unipolar depression) showed cognitive dysfunction in processing speed, memory, verbal fluency and executive function but not attention compared with controls. And post comparisons revealed that bipolar I patients performed significantly worse in these impaired cognitive domain than bipolar II and unipolar depression patients in verbal fluency and executive function. After treatment, clinically remitted bipolar I and bipolar II patients only displayed cognitive impairment in processing speed and visual memory in relative to controls, while remitted unipolar depression patients showed cognitive impairment in executive function in addition to processing speed and visual memory.
Bipolar I, bipolar II and unipolar depression patients have a similar pattern of cognitive impairment during the state of acute depressive episodes. At the clinically remission, still both bipolar disorder and unipolar depression patients showed cognitive deficits in processing speed and visual memory, and executive dysfunction might be a status-maker for bipolar disorder, but a trait-marker for unipolar depression
The main aim of this study is to investigate the capacity of a number of variables from four dimensions (clinical, psychosocial, cognitive and genetic domains) to predict the antidepressant treatment outcome, and combined the predictors in one integrate regression model with the aim to investigate which predictor contributed most.
In a semi-naturalistic prospective cohort study with a total of 241 fully assessed MDD patients, decrease in HAM-D scores from baseline to after 6 weeks of treatment was used to measure the antidepressant treatment outcome.
The clinical and psychosocial model (R2 = 0.451) showed that HAM-D scores at baseline and MMPI-2 scale paranoia was the best clinical and psychosocial predictor of treatment outcome respectively. The cognitive model (R2 = 0.502) revealed that combination of better performance on TMT-B test and worse performance on TOH and WAIS-R Digit Backward testes could predict decline in HAM-D scores. The genetics analysis only found median of percent improvement in HAM-D scores in G-allele of GR gene BclI polymorphism carriers (72.2%) was significant lower than that in non-G allele carriers (80.1%). The integrate model showed that three predictors, combination of HAM-D scores at baseline, MMPI-2 scale paranoia and TMT-B test, explained 57.1% of the variance.
Three markers, HAM-D scores at baseline, MMPI-2 scale paranoia and TMT-B test, might serve as predictor of antidepressant outcome in daily psychiatric practice.
In Canada, recreational use of cannabis was legalized in October 2018. This policy change along with recent publications evaluating the efficacy of cannabis for the medical treatment of epilepsy and media awareness about its use have increased the public interest about this agent. The Canadian League Against Epilepsy Medical Therapeutics Committee, along with a multidisciplinary group of experts and Canadian Epilepsy Alliance representatives, has developed a position statement about the use of medical cannabis for epilepsy. This article addresses the current Canadian legal framework, recent publications about its efficacy and safety profile, and our understanding of the clinical issues that should be considered when contemplating cannabis use for medical purposes.
In this paper we derive sufficient conditions for the permanence and ergodicity of a stochastic predator–prey model with a Beddington–DeAngelis functional response. The conditions obtained are in fact very close to the necessary conditions. Both nondegenerate and degenerate diffusions are considered. One of the distinctive features of our results is that they enable the characterization of the support of a unique invariant probability measure. It proves the convergence in total variation norm of the transition probability to the invariant measure. Comparisons to the existing literature and matters related to other stochastic predator–prey models are also given.
Epilepsy is a common medical condition for which physicians perform driver fitness assessments. The Canadian Medical association (CMA) and the Canadian Council of Motor transportation administrators (CCMTA) publish documents to guide Canadian physicians’ driver fitness assessments.
We aimed to measure the consistency of driver fitness counseling among epileptologists in Canada, and to determine whether inconsistencies between national guidelines are associated with greater variability in counseling instructions.
We surveyed 35 epileptologists in Canada (response rate 71%) using a questionnaire that explored physicians’ philosophies about driver fitness assessments and counseling practices of seizure patients in common clinical scenarios. Of the nine scenarios, CCMTA and CMA recommendations were concordant for only two. Cumulative agreement for all scenarios was calculated using Kappa statistic. Agreement for concordant (two) vs. discordant (seven) scenarios were split at the median and analyzed using the Wilcoxon signed rank sum test.
Overall the agreement between respondents for the clinical scenarios was not acceptable (Kappa=0.28). For the two scenarios where CMa and CCMta guidelines were concordant, specialists had high levels of agreement with recommendations (89% each). A majority of specialists disagreed with CMa recommendations in three of seven discordant scenarios. The lack of consistency in respondents’ agreement attained statistical significance (p<0.001).
Canadian epileptologists have variable counseling practices about driving, and this may be attributable to inconsistencies between CMa and CCMta medical fitness guidelines. This study highlights the need to harmonize driving recommendations in order to prevent physician and patient confusion about driving fitness in Canada.
Approximately one in three patients with a successful epilepsy surgery will have seizure recurrence following antiepileptic drugs (AED) withdrawal. The value of postoperative testing for predicting seizure relapse after AED tapering is not clear. The purpose of this study was to review the literature for evidence on the use of postoperative investigations before AED discontinuation after successful epilepsy surgery. We were unable to identify studies on the prognostic value of postoperative magnetic resonance imaging and AED blood levels. The literature review yielded seven studies on the predictive value of electroencephalography. Four studies found no association between interictal discharges (IED) and seizure relapse. These studies suffered from various limitations due to their retrospective design and generally small cohorts. Two of the three studies reporting a positive association were prospective and provided strong evidence of an increased risk of seizure recurrence with presence of postoperative IED in successfully operated patients undergoing AED withdrawal.
We describe the characteristics of a series of thin film tin oxide films grown by plasma-assisted molecular beam epitaxy on r-plane sapphire substrates over a range of flux and substrate temperature conditions. A mixture of both SnO2 and SnO are detected in several films, with the amount depending on growth conditions, most particularly the substrate temperature. Electrical measurements were not possible on all samples due to roughness related issues with contacting, but at least one film exhibited p-type characteristics depending on measurement conditions, and one sample exhibited significant persistent photoconductivity upon ultraviolet excitation in a metal-semiconductor-metal device structure.
In this study, the efficiency of different types of
pulsed electrical discharges for the removal of organic pollutants from
wastewater has been determined. Three discharge types, either in the water
volume or in close proximity to the water surface are studied. The
production of hydrogen peroxide in pure water, and the degradation of two
typical pollutants (4-chlorophenol and 4-nitrophenol) is measured together
with the amount of electrical energy dissipated in discharges. It is shown
that the energy yield for the degradation of organic pollutants, expressed
in terms of degraded moles per Joule, strongly depends on the discharge
type. The highest efficiency is obtained with pulsed corona discharges in
humid air above the water surface. A lower efficiency is found with spark
discharges in water, and the less efficient process is constituted by
streamer discharges in water. The influence of ferrous ions added to
solutions is also very different according to the discharge type. This helps
to get a better understanding of the degradation processes involved with the
different discharge types.
Cell encapsulation has been broadly investigated as a technology to provide immunoprotection for transplanted endocrine cells. Here we develop a new fabrication method that allows for rapid, homogenous microencapsulation of insulin-secreting cells with varying microscale geometries and asymmetrically modified surfaces. Micromolding systems were developed using polypropylene mesh, and the mesh material/surface properties associated with efficient encapsulation were identified. Cells encapsulated using these methods maintain desirable viability and preserve their ability to proliferate and secrete insulin in a glucose-responsive manner. This new cell encapsulation approach enables a practical route to an inexpensive and convenient process for the generation of cell-laden microcapsules without requiring any specialized equipment or microfabrication process.
To date, there has been no large-scale survey of geriatric depression (GD) involving both rural and urban areas in China using standardized assessment tools and diagnostic criteria. This study aimed to determine the 12-month and lifetime prevalence rates of GD and sociodemographic correlates in urban and rural regions of Beijing, China.
A total of 1601 elderly patients (aged ⩾60 years) were randomly selected and interviewed in Beijing using the Composite International Diagnostic Interview (CIDI 1.0). Basic sociodemographic and clinical data were also collected during the interviews.
The overall 12-month prevalence of GD was 4.33%, and the 12-month prevalence rates for men and women were 2.65% and 5.83% respectively. The overall lifetime prevalence of GD was 7.83%, and lifetime prevalence rates for men and women were 4.65% and 10.66% respectively. Female sex, lower educational level, monthly income, rural abode, and the presence of one or more major medical conditions were associated with increased risk of GD. Of the GD subjects interviewed, 25.2% were receiving some type of treatment, with only 4.7% preferring to seek treatment from mental health professionals.
Although still relatively low by international standards, there is an increasing trend in the prevalence of GD in China. The low percentage of subjects treated for GD is a major public health concern that should be addressed urgently.
Mesa and planar geometry GaN Schottky rectifiers were fabricated on 3-12µm thick epitaxial layers. In planar diodes utilizing resistive GaN, a reverse breakdown voltage of 3.1 kV was achieved in structures containing p-guard rings and employing extension of the Schottky contact edge over an oxide layer. In devices without edge termination, the reverse breakdown voltage was 2.3 kV. Mesa diodes fabricated on conducting GaN had breakdown voltages in the range 200-400 V, with on-state resistances as low as 6m Ω·cm−2.
Different ions (Ti+, O+, Fe+, Cr+) were implanted at multiple energies into GaN field effect transistor structures (n and p-type). The implantation was found to create deep states with energy levels in the range EC −0.20 to 0.49 eV in n-GaN and at EV +0.44 eV in p-GaN after annealing at 450-650 °C. The sheet resistance of the GaN was at a maximum after annealing at these temperatures, reaching values of ∼4×1012 Ω/□ in n-GaN and ∼1010 Ω/□ in p-GaN. The mechanism for the implant isolation was damage-related trap formation for all of the ions investigated, and there was no evidence of chemically induced isolation.
The development of a self-aligned fabrication process for small emitter contact area (2×4 um2) GaN/AlGaN heterojunction bipolar transistors and GaN bipolar junction transistors is described. The process features dielectric-spacer sidewalls, low damage dry etching and selected-area regrowth of p-GaAs(C) on the base contact or n-GaN/AlGaN on the emitter contact. Series resistance effects are still found to influence the device performance.
GaN and Al0.25Ga0.75N lateral Schottky rectifiers were fabricated either with (GaN) or without (AlGaN) edge termination. The reverse breakdown voltage VB (3.1 kV for GaN with both p+ guard rings and metal overlap edge terminations; 4.3 kV for Al0.25Ga0.75N without edge termination) displayed a negative temperature coefficient of −6.0 ± 0.4 V·K−1 for both types of rectifiers. The reverse current originated from contact periphery leakage at moderate bias, while the forward turn-on voltage at a current density of 100A·Cm−2 was ∼5 V for GaN and ∼7.5 V for AlGaN. The on-state resistances, RON, were 0.13 Δcm2 for GaN and 2.3 Δcm2 for AlGaN, producing figures-or-merit (VRB)2/RON of 73.9 and 8.2 MW.Cm−2, respectively. The activation energy of the reverse leakage was 0.13 eV at moderate bias.
We report on the dc performance of the first GaN pnp bipolar junction transistor. The structure was grown by MOCVD on c-plane sapphire substrates and mesas formed by low damage Inductively Coupled Plasma etching with a Cl2/Ar chemistry. The dc characteristics were measured up to VBC of 65 V in the common base mode and at temperatures up to 250°C. Under all conditions, IC ∼ IE indicated higher emitter injection efficiency. The offset voltage was ≤ 2 V and the devices were operated up to power densities of 13.9 kW·cm−2.
Recent advances in developing process modules for GaN power devices are reviewed. These processes include damage removal in dry etched n- and p-GaN, implant doping and isolation, novel gate dielectrics, improved Schottky and ohmic contacts and deep via etching of SiC for hybrid GaN/SiC structures.
The effects of dc chuck self-bias and high density source power (which predominantly control ion energy and ion flux, respectively) on the electrical properties of n-GaN Schottky diodes exposed to Inductively Coupled Plasma of Cl2/Ar were examined. Both parameters were found to influence the diode performance, by reducing the reverse breakdown voltage and Schottky barrier height. All plasma conditions were found to produce a nitrogen-deficient surface, with a typical depth of the non-stoichiometry being ∼ 500 Å. Post-etch annealing was found to partially restore the diode characteristics.
Low resistance ohmic contacts are difficult to form to p-type GaN and AlGaN due to the unavailability of growth methods for highly p-doped GaN and AlGaN. A p-type carbon-doped GaAs regrowth on p-GaN prior to ohmic metallization has been shown in previous work to improve contact resistance to p-GaN . Applying the regrowth method to the p-base regions of npn structured bipolar transistors, AlGaN/GaN heterojunction bipolar transistors and GaN bipolar junction transistors have been demonstrated. GaN/AlGaN epilayers were grown with a molecular beam epitaxy system. Highly carbon-doped p-GaAs (1020 cm−3) was regrown on the devices (∼500 Å) in the base contact region by metal organic chemical vapor deposition after emitter mesa etching. Emitter and base mesa structures were formed by Inductively Coupled Plasma etching under low damage conditions with a Cl2/Ar chemistry. SiO2 was used for emitter sidewall formation to reduce leakage current to the emitter, as well as for a mask for GaAs base regrowth. Very high current densities were obtained for common base operation in both device types. The devices were operable at 250 °C.
Mesa and planar geometry GaN Schottky rectifiers were fabricated on 3-12µm thick epitaxial layers. In planar diodes utilizing resistive GaN, a reverse breakdown voltage of 3.1 kV was achieved in structures containing p-guard rings and employing extension of the Schottky contact edge over an oxide layer. In devices without edge termination, the reverse breakdown voltage was 2.3 kV. Mesa diodes fabricated on conducting GaN had breakdown voltages in the range 200-400 V, with on-state resistances as low as 6m Ωcm−2.
Silicon oxynitride films, fabricated by direct thermal growth and annealing in N2O or NO, were analyzed by Angle-Resolved X-ray Photoelectron Spectroscopy (ARXPS). It is seen that for the samples processed in N2O, N is bonded as Si3N4 only, irrespective of whether the fabrication was done on bare Si or on an oxide pre-grown in O2. But the films processed in NO depict additional bonding arrangements, namely, non-stoichiometric SiOxNy, (Si-)2-N-O, and Si-N(-O)2. These bonding states are found to be concentrated in a higher proportion above the oxynitride/substrate interface. Further, it is seen that annealing of a pre-grown oxide in NO for 30 min incorporates the same bonding states as by direct growth in NO for as long as 120 min. Also, a critical N concentration (between 1.9% and 2.3%) is required for the incorporation of the Si-N(-O)2 structure, observed at 400.7 eV. Besides enhancing the overall understanding of the progress of silicon oxynitridation process in N2O and NO, these findings can help significantly towards developing process-property relationships for incorporation of N with the desired bonding state(s) at specific positions within an oxynitride film.