p-GaAs nanowire MESFETs with near-thermal limit gating

Difficulties in obtaining high-performance p-type transistors and gate insulator charge-trapping effects present two major challenges for III-V complementary metal-oxide semiconductor (CMOS) electronics. We report a p-GaAs nanowire metal-semiconductor field-effect transistor (MESFET) that eliminates the need for a gate insulator by exploiting the Schottky barrier at the metal-GaAs interface. Our device beats the best-performing p-GaSb nanowire metal-oxide-semiconductor field effect transistor (MOSFET), giving a typical sub-threshold swing of 62 mV/dec, within 4% of the thermal limit, on-off ratio $\sim 10^{5}$, on-resistance ~700 k$\Omega$, contact resistance ~30 k$\Omega$, peak transconductance 1.2 $\mu$S/$\mu$m and high-fidelity ac operation at frequencies up to 10 kHz. The device consists of a GaAs nanowire with an undoped core and heavily Be-doped shell. We carefully etch back the nanowire at the gate locations to obtain Schottky-barrier insulated gates whilst leaving the doped shell intact at the contacts to obtain low contact resistance. Our device opens a path to all-GaAs nanowire MESFET complementary circuits with simplified fabrication and improved performance

A GPS-Less Localization and Mobility Modelling (LMM) System for Wildlife Tracking

Existing wildlife tracking solutions typically use sensor nodes with specialised facilities, such as long-range radio, solar array of cells and Global Positioning System (GPS). This introduces additional manufacturing cost, increased energy and memory consumptions and increased sensor node weight. This paper proposes a novel Localization and Mobility Modelling (LMM) system, that can carry out wildlife tracking by merely using low-cost, lightweight sensor nodes and using short-range peer-to-peer communication facilities only, i.e. without the need for any specialised facilities. This is done by using two computationally simple operations, which are: (i) aggregated data collections from sensor nodes via peer-to-peer communications in a distributed manner, and (ii) estimation of sensor nodes' movement traces using trilateration. The computational load placed on each sensor node is just that of data collection and aggregation, whereas movement traces estimation is carried out on a backend server, separated from the sensor nodes. In the design of the LMM system, we have: (i) carried out an empirical evaluation of different parameter value settings for data collection to develop a Multi-Zone Multi-Hierarchy (MZMH) communication structure, (ii) demonstrated a novel use of an Aggregation based Topology Learning (ATL) protocol for collecting sensor nodes' topology data using peer-to-peer multi-hop communications, and (iii) used a novel Location Estimation (LE) method for estimating sensor nodes' movement traces from the collected topology data. The evaluation results show that the LMM system can accurately estimate sensor nodes' movement traces but with significantly less energy and memory costs, demonstrating its cost-efficiency as compared to the related wildlife tracking solutions. © 2020 IEEE

First Record of Cardiocondyla obscurior Wheeler, 1929 (Hymenoptera: Formicidae: Myrmicinae) for Pakistan

Ants of the genus Cardiocondyla are considered omnivorous in nature. This genus is native to Afrotropical, Australasia, Indomalaya, Malagasy, Oceania, and Palearctic regions. A total of 72 valid species and 2 valid subspecies has been described worldwide. However, little is known about these ants in Pakistan. As a result of a survey of different sites in the Gatwala park of district Faisalabad during 2018, we collected individuals of the genus Cardiocondyla. Collected specimens were identified using the most recent and available literature. Prior to current work, only two species of this genus were reported for Pakistan. In this study we added the first record of Cardiocondyla obscurior for Pakistan, followed by a brief description, distribution, and identification key

The Existence of Einstein Static Universes and their Stability in Fourth order Theories of Gravity

We investigate whether or not an Einstein Static universe is a solution to the cosmological equations in $f(R)$ gravity. It is found that only one class of $f(R)$ theories admits an Einstein Static model, and that this class is neutrally stable with respect to vector and tensor perturbations for all equations of state on all scales. Scalar perturbations are only stable on all scales if the matter fluid equation of state satisfies $c_s^2>\frac{\sqrt{5}-1}{6}\approx 0.21$. This result is remarkably similar to the GR case, where it was found that the Einstein Static model is stable for $c_s^2>{1/5}$.Comment: Minor changes, To appear in PR

Large-scale perturbations on the brane and the isotropy of the cosmological singularity

We present the complete set of propagation and constraint equations for the kinematic and non-local first order quantities which describe general linear inhomogeneous and anisotropic perturbations of a flat FRW braneworld with vanishing cosmological constant and decompose them in the standard way into their scalar, vector and tensor contributions. A detailed analysis of the perturbation dynamics is performed using dimensionless variables that are specially tailored for the different regimes of interest; namely, the low energy GR regime, the high energy regime and the dark energy regime. Tables are presented for the evolution of all the physical quantities, making it easy to do a detailed comparison of the past asymptotic behaviour of the perturbations of these models. We find results that exactly match those obtained in the analysis of the spatially inhomogeneous $G_{2}$ braneworld cosmologies presented recently; i.e., that isotropization towards the ${\cal F}_b$ model occurs for $\gamma > 4/3$.Comment: 13 pages, revtex

Carrier dynamics in InP nanopillar arrays fabricated by low-damage etching

We present a comprehensive characterization of the optical quality of InP nanopillars (NPs) fabricated by a top down approach using micro-photoluminescence (μ-PL), time-resolved PL, and cathodoluminescence (CL). A lattice matched InGaAs layer provided beneath the 1 μm tall NPs functions as a “detector” in CL for monitoring carrier diffusion in InP NP. Carrier feeding to the InGaAs layer indicated by a double exponential PL decay is confirmed through CL mapping. Carrier lifetimes of over 1 ns and the appreciably long diffusion lengths (400–700 nm) in the InP NPs indicate very low surface damage making them attractive for optoelectronic applications.The work was performed within the Linne Center for Advanced Optics and Photonics [Grant No.: 349-2007-8664] funded by the Swedish Research Council (VR). Support from the EU network of excellence “Nanophotonics for Energy Efficiency” [Grant No.: 248855] and from “Nanordsun” [Grant No.: 10048] funded by Nordic Innovation centre are also acknowledged. S.N. and N.S. acknowledge the Higher Education Commission of Pakistan for partially supporting their PhD studies (scholarship). The CL study was done in the nmC@LU with support from VR and Kurt Alice Wallenberg (KAW) foundation. The authors thank M. Hammar and J. Berggren for the MOVPE growth

Formulation, characterization and wound-healing potential of emulgel and in-situ gel containing root extract of Saussurea lappa Clarke (Asteraceae)

Purpose: To investigate the wound-healing potential of herbal formulations (emulgels and in situ gels) containing Saussurea lappa root extract  (SLRE) via excision wound induction in albino rats. Methods: Preliminary phytochemical analysis of the methanol extract of roots of Saussurea lappa (SLRE) was performed using standard  procedures. In vitro anti-inflammatory assay of SLRE was conducted using heat-induced hemolysis method at a concentration of 100 μg/mL. Acute  toxicity of SLRE was also evaluated in mice at a single dose of 1000 mg/kg for 24 h. Emulgels and in situ gels were prepared using different concentrations of SLRE and assessed for their organoleptic and physical properties. In vitro drug release studies of the prepared formulations were carried out by Franz diffusion cell and the data fitted into various pharmacokinetic models. Wound healing was assessed using excision wound induction (380 mm2) on dorsal surface of male albino rats. Each formulation (F4, F5, F6, G1, G2 and G3) and pyodine gel (standard) were applied topically (0.5 g) for 20 days. Wound contraction was measured every fourth day. Results: SLRE showed 42.8 % inhibition in heat-induced hemolysis on erythrocyte membrane model, compared to aspirin (positive control).  Moreover, SLRE did not cause mortality in mice at the given doses. All the formulations were stable after one month stability check at 40 °C for emulgels and at 25 °C for in situ gels. All the formulations followed first order drug release pattern. In situ gel (G3) exhibited better wound healing (100 ± 0.0028) than emulgel (F6, 99 ± 0.004) containing 5 g extract and standard pyodine gel (91 ± 0.014, p <0.05). Conclusion: The results indicate that in situ gel of SLRE exhibits significant wound healing in rats. Thus, the findings present a strategy for the formulation of gel products with better wound healing potentials. Keywords: Saussurea lappa, Wound healing, Emulgel, In situ gel, Herbal formulatio

Development of an on-job mentorship programme to improve nursing experience for enhanced patient experience of compassionate care

Background: Evidence suggests improvement in nursing staff satisfaction, competence, and retention after implementation of evidence-based mentorship programmes. When guided by a framework of compassion, mentoring as a caring action can not only build healthy, transformative relationships but a similar behavior is reciprocated to patients which subsequently can drive patient experience of care. However, examples of on-job mentorship programs for nurses in low- and middle-income countries (LMIC) are limited.Objective: The objective of the study was to develop an on-job nursing mentorship programme using a compassionate framework aimed at improving nurses\u27 experience and thus enhancing patient experience in a tertiary care hospital in Pakistan.Methods: Designed as an intervention development study, it was completed between January 2018-December 2019. The programme was developed by a team composed of service and nursing leadership, director patient experience of care and a compassion specialist using a theory of change model. The package followed a series of steps, a) identification of a framework, b) creation of working group c) needs assessment and d) multiple meetings to frame the model followed by implementing the preconditions for roll-out of the programme with the frontline staff.Results: The eventual outcome was improving the patient\u27s experience of compassion while the intermediate outcome was to have nurses demonstrate compassionate care. The pre-conditions were identified as: recruitment of staff with appropriate skills for pediatric care, provision of compassionate experience to the frontline nurses by addressing their specific pain points, development of competent head nurses as supervisors and creation of a compassionate culture. To ensure the pre-conditions, various interventions were planned with some implemented through the course of the study while others are in the process of being rolled out. These involved, inclusion of pediatric compassion specific module during orientation of new hires, creation of space to talk about compassionate skills with staff, provision of trainings and mentorship to create competent head nurses, and creating a culture that promoted and recognized compassionate care values.Conclusion: The approach helped to delineate feasible pathways for an on-job compassionate mentorship programme enhancing routine supervisors\u27 role as facilitators of compassionate care

Intentional and unintentional poisoning in Pakistan: a pilot study using the Emergency Departments surveillance project.

Background: Acute poisoning is one of the most common reasons for emergency department visits around the world. In Pakistan, the epidemiological data on poisoning is limited due to an under developed poison information surveillance system. We aim to describe the characteristics associated with intentional and unintentional poisoning in Pakistan presenting to emergency departments.Methods: The data was extracted from the Pakistan National Emergency Department Surveillance (Pak-NEDS) which was an active surveillance conducted between November 2010 and March 2011. All patients, regardless of age, who presented with poisoning to any of Pakistan\u27s seven major tertiary care centers\u27 emergency departments, were included. Information about patient demographics, type of poisoning agent, reason for poisoning and outcomes were collected using a standard questionnaire.Results: Acute poisoning contributed to 1.2% (n = 233) of patients with intentional and unintentional injuries presenting to EDs of participating centers. Of these, 68% were male, 54% were aged 19 to 44 and 19% were children and adolescents (\u3c18 years). Types of poisoning included chemical/gas (43.8%), drug/medicine (27%), alcohol (16.7%) and food/plant (6%). In half of all patients the poisoning was intentional. A total of 11.6% of the patients were admitted and 6.6% died.Conclusions: Poisoning causes more morbidity and mortality in young adults in Pakistan compared to other age groups, half of which is intentional. Improving mental health, regulatory control for hazardous chemicals and better access to care through poison information centers and emergency departments will potentially help control the problem

Are braneworlds born isotropic?

It has recently been suggested that an isotropic singularity may be a generic feature of brane cosmologies, even in the inhomogeneous case. Using the covariant and gauge-invariant approach we present a detailed analysis of linear perturbations of the isotropic model ${\cal F}_b$ which is a past attractor in the phase space of homogeneous Bianchi models on the brane. We find that for matter with an equation of state parameter $\gamma > 1$, the dimensionless variables representing generic anisotropic and inhomogeneous perturbations decay as $t\to 0$, showing that the model ${\cal F}_b$ is asymptotically stable in the past. We conclude that brane universes are born with isotropy naturally built-in, contrary to standard cosmology. The observed large-scale homogeneity and isotropy of the universe can therefore be explained as a consequence of the initial conditions if the brane-world paradigm represents a description of the very early universe.Comment: Changed to match published versio