Analysis of risk management practices among cassava farmers in Ideato South Local Government Area, Imo State, Nigeria

Risks are pervasive and inescapable in agriculture. There has been great concern about the problems posed by risk in agriculture. This apprehension stems from the harmful effects of risk on the output of farmers in Nigeria. This study examines risk management practices among cassava farmers in Ideato South Local Government Area (LGA) of Imo State, Nigeria. It specifically sought to identify the types of risks encountered, management practices adopted, and socio-demographic factors that influence cassava yields. The study used purposive and multistage sampling techniques to sample 90 cassava farmers from seven autonomous communities in Ideato South LGA. Data were collected using a structured questionnaire. Inferential and descriptive statistics such as multiple regression model, mean, percentage frequency counts were used in data analysis. Findings showed that poor yield due to bad weather conditions and inadequate transportation systems were the most intense risks faced by cassava farmers. The major farmers’ risk management strategies in order of importance were mixed cropping, mixed farming, off-farm investment and Insurance. Insurance was least ranked mainly because the farmers lacked adequate information on the insurance benefits. Off-farm income and farming experience were the socio-demographic variables that positively influenced the output of cassava, implying that increase in these variables would increase the output of cassava. On the other hand, age as a variable was significant but had adverse effects on output. The findings show that risk cannot be eliminated in the agricultural production process because agricultural production has a high dependence on the vagaries of nature. The study recommends that farmers be encouraged to diversify their farming operations through a diversification process where the farmers produce several products rather than cassava, a single product. The use of improved cassava varieties should be encouraged. Additionally, farmers should increase their involvement in more income-generating activities to plummet the risk among cassava producers.&nbsp

Curvature-dimension inequalities and Li-Yau inequalities in sub-Riemannian spaces

In this paper we present a survey of the joint program with Fabrice Baudoin originated with the paper \cite{BG1}, and continued with the works \cite{BG2}, \cite{BBG}, \cite{BG3} and \cite{BBGM}, joint with Baudoin, Michel Bonnefont and Isidro Munive.Comment: arXiv admin note: substantial text overlap with arXiv:1101.359

Advanced micro and nano manufacturing technologies used in medical domain

This paper focuses on the aspects of advanced manufacturing technologies, namely micro and nano manufacturing (MNM) capabilities which are particularly relevant to medical domain. In recent years, the so called disruptive technologies have enabled engineers and clinicians to collaborate in solving complex problems which require advanced MNM capabilities to develop medical applications. As a result what was nearly impossible a few years ago, due to limitations in machining and manufacturability of micro and nano scale artefacts, are now made possible thanks to innovative manufacturing processes and technologies. The potential medical applications of the new MNM methods are immense and in this paper four potential uses, namely as medical devices, lab on chips, and brain implants are presented and discussed. These works were based on different projects undertaken by researchers at Cardiff University, UK. The manufacturing costs, though initially high, are expected to reduce over time as the technologies mature and become more widely available. Introducing these MNM technologies and disseminating these results to healthcare engineering, for a better quality of medical diagnosis and treatments with cost-effective solutions, will greatly benefit the majority of population who live in the developing countries in receiving appropriate and affordable medical care to achieve improvements in their quality of life

On Exceptional Times for generalized Fleming-Viot Processes with Mutations

If $\mathbf Y$ is a standard Fleming-Viot process with constant mutation rate (in the infinitely many sites model) then it is well known that for each $t>0$ the measure $\mathbf Y_t$ is purely atomic with infinitely many atoms. However, Schmuland proved that there is a critical value for the mutation rate under which almost surely there are exceptional times at which $\mathbf Y$ is a finite sum of weighted Dirac masses. In the present work we discuss the existence of such exceptional times for the generalized Fleming-Viot processes. In the case of Beta-Fleming-Viot processes with index $\alpha\in\,]1,2[$ we show that - irrespectively of the mutation rate and $\alpha$ - the number of atoms is almost surely always infinite. The proof combines a Pitman-Yor type representation with a disintegration formula, Lamperti's transformation for self-similar processes and covering results for Poisson point processes

Microwave Oscillations of a Nanomagnet Driven by a Spin-Polarized Current

We describe direct electrical measurements of microwave-frequency dynamics in individual nanomagnets that are driven by spin transfer from a DC spin-polarized current. We map out the dynamical stability diagram as a function of current and magnetic field, and we show that spin transfer can produce several different types of magnetic excitations, including small-angle precession, a more complicated large-angle motion, and a high-current state that generates little microwave signal. The large-angle mode can produce a significant emission of microwave energy, as large as 40 times the Johnson-noise background.Comment: 12 pages, 3 figure

The Significance of the CC-Numerical Range and the Local CC-Numerical Range in Quantum Control and Quantum Information

This paper shows how C-numerical-range related new strucures may arise from practical problems in quantum control--and vice versa, how an understanding of these structures helps to tackle hot topics in quantum information. We start out with an overview on the role of C-numerical ranges in current research problems in quantum theory: the quantum mechanical task of maximising the projection of a point on the unitary orbit of an initial state onto a target state C relates to the C-numerical radius of A via maximising the trace function |\tr \{C^\dagger UAU^\dagger\}|. In quantum control of n qubits one may be interested (i) in having U\in SU(2^n) for the entire dynamics, or (ii) in restricting the dynamics to {\em local} operations on each qubit, i.e. to the n-fold tensor product SU(2)\otimes SU(2)\otimes >...\otimes SU(2). Interestingly, the latter then leads to a novel entity, the {\em local} C-numerical range W_{\rm loc}(C,A), whose intricate geometry is neither star-shaped nor simply connected in contrast to the conventional C-numerical range. This is shown in the accompanying paper (math-ph/0702005). We present novel applications of the C-numerical range in quantum control assisted by gradient flows on the local unitary group: (1) they serve as powerful tools for deciding whether a quantum interaction can be inverted in time (in a sense generalising Hahn's famous spin echo); (2) they allow for optimising witnesses of quantum entanglement. We conclude by relating the relative C-numerical range to problems of constrained quantum optimisation, for which we also give Lagrange-type gradient flow algorithms.Comment: update relating to math-ph/070200

Optical Magnetometry

Some of the most sensitive methods of measuring magnetic fields utilize interactions of resonant light with atomic vapor. Recent developments in this vibrant field are improving magnetometers in many traditional areas such as measurement of geomagnetic anomalies and magnetic fields in space, and are opening the door to new ones, including, dynamical measurements of bio-magnetic fields, detection of nuclear magnetic resonance (NMR), magnetic-resonance imaging (MRI), inertial-rotation sensing, magnetic microscopy with cold atoms, and tests of fundamental symmetries of Nature.Comment: 11 pages; 4 figures; submitted to Nature Physic

Macroscopic invisibility cloaking of visible light

Invisibility cloaks, which used to be confined to the realm of fiction, have now been turned into a scientific reality thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realization of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices

Genetic variation in the HLA region is associated with susceptibility to herpes zoster.

Herpes zoster, commonly referred to as shingles, is caused by the varicella zoster virus (VZV). VZV initially manifests as chicken pox, most commonly in childhood, can remain asymptomatically latent in nerve tissues for many years and often re-emerges as shingles. Although reactivation may be related to immune suppression, aging and female sex, most inter-individual variability in re-emergence risk has not been explained to date. We performed a genome-wide association analyses in 22,981 participants (2280 shingles cases) from the electronic Medical Records and Genomics Network. Using Cox survival and logistic regression, we identified a genomic region in the combined and European ancestry groups that has an age of onset effect reaching genome-wide significance (P>1.0 × 10(-8)). This region tags the non-coding gene HCP5 (HLA Complex P5) in the major histocompatibility complex. This gene is an endogenous retrovirus and likely influences viral activity through regulatory functions. Variants in this genetic region are known to be associated with delay in development of AIDS in people infected by HIV. Our study provides further suggestion that this region may have a critical role in viral suppression and could potentially harbor a clinically actionable variant for the shingles vaccine