1,008 research outputs found
Interaction between population and Enviromental Degradation
The present study investigates the long-run interrelationship among the demographic variables and environmental indicators by using the Johansen-Juselius cointegration technique and error correction model to determine the short-run dynamics of the system related to time series data for Pakistan economy, over the period 1972–2001. The paper finds the existence of a cointegrating vector, indicating a valid long-run relationship among the variables. Moreover, demographic variables have a significant effect in the short-run on AL but their short-run coefficients have an insignificant impact on CO2 emission. The empirical evidence clearly support that high population growth rates have a deleterious impact on environment. The policy implication thereof is to enhance the need of lowering population in Pakistan which seems to be a burden on the existing resources and a challenge to the environment.
A Distributed Approach for Networked Flying Platform Association with Small Cells in 5G+ Networks
The densification of small-cell base stations in a 5G architecture is a
promising approach to enhance the coverage area and facilitate the ever
increasing capacity demand of end users. However, the bottleneck is an
intelligent management of a backhaul/fronthaul network for these small-cell
base stations. This involves efficient association and placement of the
backhaul hubs that connects these small-cells with the core network.
Terrestrial hubs suffer from an inefficient non line of sight link limitations
and unavailability of a proper infrastructure in an urban area. Seeing the
popularity of flying platforms, we employ here an idea of using networked
flying platform (NFP) such as unmanned aerial vehicles (UAVs), drones, unmanned
balloons flying at different altitudes, as aerial backhaul hubs. The
association problem of these NFP-hubs and small-cell base stations is
formulated considering backhaul link and NFP related limitations such as
maximum number of supported links and bandwidth. Then, this paper presents an
efficient and distributed solution of the designed problem, which performs a
greedy search in order to maximize the sum rate of the overall network. A
favorable performance is observed via a numerical comparison of our proposed
method with optimal exhaustive search algorithm in terms of sum rate and
run-time speed.Comment: Submitted to IEEE GLOBECOM 2017, 7 pages and 4 figure
A low-power, low-cost infra-red emitter in CMOS technology
In this paper, 1 we present the design and characterization of a low-power low-cost infra-red emitter based on a tungsten micro-hotplate fabricated in a commercial 1-μm SOI-CMOS technology. The device has a 250-μm diameter resistive heater inside a 600-μm diameter thin dielectric membrane. We first present electro-thermal and optical device characterization, long term stability measurements, and then demonstrate its application as a gas sensor for a domestic boiler. The emitter has a dc power consumption of only 70 mW, a total emission of 0.8 mW across the 2.5–15-μm wavelength range, a 50% frequency modulation depth of 70 Hz, and excellent uniformity from device-to-device. We also compare two larger emitters (heater size of 600 and 1800 μm) made in the same technology that have a much higher infra-red emission, but at the detriment of higher power consumption. Finally, we demonstrate that carbon nanotubes can be used to significantly enhance the thermo-optical transduction efficiency of the emitter
ECG Morphological Variability in Beat Space for Risk Stratification After Acute Coronary Syndrome
Background: Identification of patients who are at high risk of adverse cardiovascular events after an acute coronary syndrome (ACS) remains a major challenge in clinical cardiology. We hypothesized that quantifying variability in electrocardiogram (ECG) morphology may improve risk stratification post‐ACS. Methods and Results: We developed a new metric to quantify beat‐to‐beat morphologic changes in the ECG: morphologic variability in beat space (MVB), and compared our metric to published ECG metrics (heart rate variability [HRV], deceleration capacity [DC], T‐wave alternans, heart rate turbulence, and severe autonomic failure). We tested the ability of these metrics to identify patients at high risk of cardiovascular death (CVD) using 1082 patients (1‐year CVD rate, 4.5%) from the MERLIN‐TIMI 36 (Metabolic Efficiency with Ranolazine for Less Ischemia in Non‐ST‐Elevation Acute Coronary Syndrome—Thrombolysis in Myocardial Infarction 36) clinical trial. DC, HRV/low frequency–high frequency, and MVB were all associated with CVD (hazard ratios [HRs] from 2.1 to 2.3 [P<0.05 for all] after adjusting for the TIMI risk score [TRS], left ventricular ejection fraction [LVEF], and B‐type natriuretic peptide [BNP]). In a cohort with low‐to‐moderate TRS (N=864; 1‐year CVD rate, 2.7%), only MVB was significantly associated with CVD (HR, 3.0; P=0.01, after adjusting for LVEF and BNP). Conclusions: ECG morphological variability in beat space contains prognostic information complementary to the clinical variables, LVEF and BNP, in patients with low‐to‐moderate TRS. ECG metrics could help to risk stratify patients who might not otherwise be considered at high risk of CVD post‐ACS
Assessing two spirometric criteria of pre-bronchodilator and post-bronchodilator FEV1/FVC ratio in detecting air flow obstruction
OBJECTIVES: To assess the Pre-bronchodilator criteria and the Post-bronchodilator criteria of FEV1/FVC ratio in diagnosing Airflow obstruction.
METHODS: An observational study was conducted from 1988 to 2006 at the Aga Khan University Hospital Patients referred to the pulmonary function test laboratory for spirometry with bronchodilator reversibility at the hospital during the above said period were enrolled. Forced spirometry was performed according to ATS guidelines. All patients who had pre-bronchodilator criteria of airflow obstruction were analyzed and compared with the post bronchodilator criteria.
RESULTS: A total of 4222 individuals underwent spirometry out of which 4072 individuals were studied. Using the pre bronchodilator criteria, 1375 (34%) patients had airflow obstruction. Applying the post bronchodilator criteria on the same patients, 1098 (27%) had evidence of airway obstruction. Out of these 1375 patients who had airflow obstruction by using pre-bronchodilator criteria, 277 (20%) patients had no airflow obstruction by using the post bronchodilator criteria. Out of these 277 patients, 52% had significant airways reversibility as evidenced by \u3e12% increase in their FEV1 pre and post bronchodilator.
CONCLUSION: Pre bronchodilator criteria for detection of airflow obstruction overestimate the diagnosis of airflow obstruction and by using post bronchodilator criteria for airway obstruction on spirometry, decreases this over diagnosis of the conditio
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