Women Farmers’ Characteristics and Perception towards Climate Change and Variability in Iringa District, Tanzania

Perception is widely recognized to be a precondition for adaptation to climate change and variability. This study was conducted in the semi-arid part of Iringa District in Tanzania to establish association between women farmers’ characteristics and perception towards climate change and variability. A cross-sectional research design and multistage random sampling technique was used in selecting 385 women farmers. Quantitative and qualitative data were analyzed by using Statistical Package for Social Sciences (SPSS) computer software and content analysis respectively. Findings show that majority of women farmers in study area have perceived high perception on climate change and variability as indicated by increase in number of seasons without enough rainfall, poor distribution of rainfall during rain season, rainfall peak season ending earlier than normal and increases of temperature in the study area. The study also observed significant difference (P< 0.05) in perception between women farmers with less numbers of years in farming and those with more. Nevertheless, the study found existence of no significant difference (P>0.05) in perception between women farmers with different characteristics such as marital status, education level attained, household size, being household head and land size cultivated. The study concluded that differences in women farmers’ characteristics in the study area did not affect their perception toward climate change and variability. Therefore, the study recommends that, high level in perception on CC & V by women farmers in surveyed area should be taken as the stepping stone by the government and other development partners for setting up measures in helping women farmers to adapt to CC & V. Key words:  Women farmer, perception, climate variability, climate change and adaptation

Lowest-energy structures of 13-atom binary clusters: Do icosahedral clusters exist in binary liquid alloys?

Although the existence of 13-atom icosahedral clusters in one-component close-packed undercooled liquids was predicted more than half a century ago by Frank, the existence of such icosahedral clusters is less clear in liquid alloys. We study the lowest-energy structures of 13-atom AxB13-x Lennard-Jones binary clusters using the modified space-fixed genetic algorithm and the artificial Lennard-Jones potential designed by Kob and Andersen. Curiously, the lowest-energy structures are non-icosahedral for almost all compositions. The role played by the icosahedral cluster in a binary glass is questionable.Comment: 10 pages, 3 figure (conference paper of LAM12) to be published in J. Non-Crystalline Solid

Viscosity in spherically symmetric accretion

The influence of viscosity on the flow behaviour in spherically symmetric accretion, has been studied here. The governing equation chosen has been the Navier-Stokes equation. It has been found that at least for the transonic solution, viscosity acts as a mechanism that detracts from the effectiveness of gravity. This has been conjectured to set up a limiting scale of length for gravity to bring about accretion, and the physical interpretation of such a length-scale has been compared with the conventional understanding of the so-called "accretion radius" for spherically symmetric accretion. For a perturbative presence of viscosity, it has also been pointed out that the critical points for inflows and outflows are not identical, which is a consequence of the fact that under the Navier-Stokes prescription, there is a breakdown of the invariance of the stationary inflow and outflow solutions -- an invariance that holds good under inviscid conditions. For inflows, the critical point gets shifted deeper within the gravitational potential well. Finally, a linear stability analysis of the stationary inflow solutions, under the influence of a perturbation that is in the nature of a standing wave, has indicated that the presence of viscosity induces greater stability in the system, than has been seen for the case of inviscid spherically symmetric inflows.Comment: 7 pages. Minor changes made in the version published in MNRA

Fast switching tunable laser sources for wavelength division multiplexing in passive optical access networks

Tunable laser structures with nanosecond switching time between wavelength channels and low-power injection locking are demonstrated on a low-cost platform. These lasers are suitable as source or slave lasers in WDM passive optical access networks

The relationship between inspiratory lung function parameters and airway hyper-responsiveness in subjects with mild to moderate COPD

Background: The aim of this study was to evaluate the effects of increasing doses of inhaled histamine on the forced expiratory volume in one second (FEV 1), inspiratory lung function parameters (ILPs) and dyspnea in subjects with mild to moderate chronic obstructive pulmonary disease (COPD). Methods. Thirty-nine (27 males and 12 females) stable COPD patients (GOLD stages I and II) inhaled a maximum of six sequential doses of histamine according to ERS standards until one of these provocative doses produced a 20% decrease in FEV 1 (PD 20). The effects on the FEV 1, the forced inspiratory volume in one second (FIV 1), inspiratory capacity (IC), forced inspiratory flow at 50% of the vital capacity (FIF50), peak inspiratory flow (PIF) and dyspnea score by a visual analogue scale (VAS) were measured and investigated after each dose step. Results: After each dose of histamine, declines in all of the lung function parameters were detected; the largest decrease was observed in the FEV 1. At the PD 20 endpoint, more FEV 1 responders than ILP responders were found. Among the ILPs, the FIV 1 and IC best predicted which patients would reach the PD 20 endpoint. No significant correlations were found between any of the lung function parameters and the VAS results. Conclusions: In COPD patients, the FEV 1 and ILPs declined after each dose of inhaled histamine. FEV 1 was more sensitive to histamine than the ILPs. Of the ILPs, FIV 1 and IC were the best predictors of reaching the PD 20 endpoint. No statistically significant correlations were found between the lung function parameters and the degree of dyspnea

Moving forward in circles: challenges and opportunities in modelling population cycles

Population cycling is a widespread phenomenon, observed across a multitude of taxa in both laboratory and natural conditions. Historically, the theory associated with population cycles was tightly linked to pairwise consumer–resource interactions and studied via deterministic models, but current empirical and theoretical research reveals a much richer basis for ecological cycles. Stochasticity and seasonality can modulate or create cyclic behaviour in non-intuitive ways, the high-dimensionality in ecological systems can profoundly influence cycling, and so can demographic structure and eco-evolutionary dynamics. An inclusive theory for population cycles, ranging from ecosystem-level to demographic modelling, grounded in observational or experimental data, is therefore necessary to better understand observed cyclical patterns. In turn, by gaining better insight into the drivers of population cycles, we can begin to understand the causes of cycle gain and loss, how biodiversity interacts with population cycling, and how to effectively manage wildly fluctuating populations, all of which are growing domains of ecological research

On the Interpretation of Energy as the Rate of Quantum Computation

Over the last few decades, developments in the physical limits of computing and quantum computing have increasingly taught us that it can be helpful to think about physics itself in computational terms. For example, work over the last decade has shown that the energy of a quantum system limits the rate at which it can perform significant computational operations, and suggests that we might validly interpret energy as in fact being the speed at which a physical system is "computing," in some appropriate sense of the word. In this paper, we explore the precise nature of this connection. Elementary results in quantum theory show that the Hamiltonian energy of any quantum system corresponds exactly to the angular velocity of state-vector rotation (defined in a certain natural way) in Hilbert space, and also to the rate at which the state-vector's components (in any basis) sweep out area in the complex plane. The total angle traversed (or area swept out) corresponds to the action of the Hamiltonian operator along the trajectory, and we can also consider it to be a measure of the "amount of computational effort exerted" by the system, or effort for short. For any specific quantum or classical computational operation, we can (at least in principle) calculate its difficulty, defined as the minimum effort required to perform that operation on a worst-case input state, and this in turn determines the minimum time required for quantum systems to carry out that operation on worst-case input states of a given energy. As examples, we calculate the difficulty of some basic 1-bit and n-bit quantum and classical operations in an simple unconstrained scenario.Comment: Revised to address reviewer comments. Corrects an error relating to time-ordering, adds some additional references and discussion, shortened in a few places. Figures now incorporated into tex

Advances in silicon phased-array receiver IC's

Phased-Arrays are increasingly used, and require Silicon implementations to result in affordable multi-beam systems. In this paper, CMOS implementations of two novel analogue beamforming multi-channel receivers will be presented. A narrow-band highly linear system exploiting switches and capacitors in advanced CMOS is presented, implementing a fully passive switched capacitor vector modulator exploiting a zero-IF I/Q mixer: This technique is not applicable to very wideband phased-array receivers. These systems require true-time delay beamforming, which is implemented in the second CMOS implementation. An innovative gm-RC implementation of a true-time delay cell is exploited in a four-channel beamforming receiver with more than L.5 GHz bandwidth, in a standard 0.13 um CMOS process. Professional phased-arrays can often not live with the dynamic range limitations imposed by these implementations. To that end a SiGe implementation of an integrated receiver was realized targeting a digital beamforming phased-array. Dynamic range and flexibility of use were the main driving factors. Alltogether, these results show large progress with respect to the feasibility of Silicon-based phased-array front-end implementation for commercial as well as professional phased-arrays. © 2012 IEEE

Relativistic nuclear structure effects in quasielastic neutrino scattering

Charged-current cross sections are calculated for quasielastic neutrino and antineutrino scattering using a relativistic meson-nucleon model. We examine how nuclear-structure effects, such as relativistic random-phase-approximation (RPA) corrections and momentum-dependent nucleon self-energies, influence the extraction of the axial form factor of the nucleon. RPA corrections are important only at low-momentum transfers. In contrast, the momentum dependence of the relativistic self-energies changes appreciably the value of the axial-mass parameter, $M_A$, extracted from dipole fits to the axial form factor. Using Brookhaven's experimental neutrino spectrum we estimate the sensitivity of M$_A$ to various relativistic nuclear-structure effects.Comment: 26 pages, revtex, 6 postscript figures (available upon request

Thermal Stabilization of the HCP Phase in Titanium

We have used a tight-binding model that is fit to first-principles electronic-structure calculations for titanium to calculate quasi-harmonic phonons and the Gibbs free energy of the hexagonal close-packed (hcp) and omega crystal structures. We show that the true zero-temperature ground-state is the omega structure, although this has never been observed experimentally at normal pressure, and that it is the entropy from the thermal population of phonon states which stabilizes the hcp structure at room temperature. We present the first completely theoretical prediction of the temperature- and pressure-dependence of the hcp-omega phase transformation and show that it is in good agreement with experiment. The quasi-harmonic approximation fails to adequately treat the bcc phase because the zero-temperature phonons of this structure are not all stable