Community violence in Dar es Salaam, Tanzania: A mixed methods study

Most homicide deaths in Dar es Salaam, Tanzania (DSM) are a result of violence arising from within the community. This type of violence is commonly called, by perpetrators and victims, “mob justice”. Unilateral non-state collective violence can take four forms: lynching, vigilantism, rioting, and terrorism. The purpose of this paper is to report what leads to death by such violence in DSM. A cross-sectional mixed methods study design was used. Surveillance data were collected on all 206 victims of “mob justice” in DSM for the year 2005. Fifteen in-depth interviews were conducted with the relatives of deceased victims, a policeman, a journalist, community members, and youths who survived these types of community violence. A focus group discussion was conducted with eight youths at risk of such violence. The deceased were young adult males and differed significantly from assault victims as to age, occupation, weapon causing death, and injury site. Ninety percent were identified as: unemployed, thieves, unknowns, or street vendors. The immediate history of the deceased usually involved theft. The stated desire of community members was to live in peace; they acknowledged that murder is unlawful. Often the victims had been warned; if transgressions continued, male community members punished the individual, which led to death. Family reactions varied from relief, to confusion, and loss. Community level violence in DSM is defensive; the goal is to protect the community. It is focused on individuals, not groups; incidents can be classified along the continuum of lynching and vigilantism in which lynching is a spontaneous reaction to deviance and vigilantism is an organised activity. Decreasing the number of deviant social acts should theoretically decrease cases of lynching and vigilantism. The most humane way to decrease petty theft is through appropriate employment.Keywords: homicide; Africa; Tanzania; vigilantism; lynching; community; mo

Reducing smoking in adolescents: cost-effectiveness results from the cluster randomized ASSIST (A Stop Smoking In Schools Trial)

Introduction: School-based smoking prevention programmes can be effective, but evidence on cost-effectiveness is lacking. We conducted a cost-effectiveness analysis of a school-based “peer-led” intervention.<p></p> Methods: We evaluated the ASSIST (A Stop Smoking In Schools Trial) programme in a cluster randomized controlled trial. The ASSIST programme trained students to act as peer supporters during informal interactions to encourage their peers not to smoke. Fifty-nine secondary schools in England and Wales were randomized to receive the ASSIST programme or usual smoking education. Ten thousand seven hundred and thirty students aged 12–13 years attended participating schools. Previous work has demonstrated that the ASSIST programme achieved a 2.1% (95% CI = 0%–4.2%) reduction in smoking prevalence. We evaluated the public sector cost, prevalence of weekly smoking, and cost per additional student not smoking at 24 months.<p></p> Results: The ASSIST programme cost of £32 (95% CI = £29.70–£33.80) per student. The incremental cost per student not smoking at 2 years was £1,500 (95% CI = £669–£9,947). Students in intervention schools were less likely to believe that they would be a smoker at age 16 years (odds ratio [OR] = 0.80; 95% CI = 0.66–0.96).<p></p> Conclusions: A peer-led intervention reduced smoking among adolescents at a modest cost. The intervention is cost-effective under realistic assumptions regarding the extent to which reductions in adolescent smoking lead to lower smoking prevalence and/or earlier smoking cessation in adulthood. The annual cost of extending the intervention to Year 8 students in all U.K. schools would be in the region of £38 million and could result in 20,400 fewer adolescent smokers.<p></p&gt

Lack of Mutual Respect in Relationship The Endangered Partner

Violence in a relationship and in a family setting has been an issue of concern to various interest groups and professional organizations. Of particular interest in this article is violence against women in a relationship. While there is an abundance of knowledge on violence against women in general, intimate or partner femicide seems to have received less attention. Unfortunately, the incidence of violence against women, and intimate femicide in particular, has been an issue of concern in the African setting. This article examines the trends of intimate femicide in an African setting in general, and in Botswana in particular. The increase in intimate femicide is an issue of concern, which calls for collective effort to address. This article also examines trends offemicide in Botswana, and the antecedents and the precipitating factors. Some studies have implicated societal and cultural dynamics as playing significant roles in intimate femicide in the African setting. It is believed that the patriarchal nature of most African settings and the ideology of male supremacy have relegated women to a subordinate role. Consequently, respect for women in any relationship with men is lopsided in favor of men and has led to abuse of women, including intimate femicide. Other militating factors in intimate femicide ,are examined and the implications for counseling to assist the endangered female partner are discussed

Space-time evolution of electron cascades in diamond

Here we describe model calculations to follow the spatio-temporal evolution of secondary electron cascades in diamond. The band structure of the insulator has been explicitly incorporated into the calculations as it affects ionizations from the valence band. A Monte-Carlo model was constructed to describe the path of electrons following the impact of a single electron of energy E 250 eV. The results show the evolution of the secondary electron cascades in terms of the number of electrons liberated, the spatial distribution of these electrons, and the energy distribution among the electrons as a function of time. The predicted ionization rates (5-13 electrons in 100 fs) lie within the limits given by experiments and phenomenological models. Calculation of the local electron density and the corresponding Debye length shows that the latter is systematically larger than the radius of the electron cloud. This means that the electron gas generated does not represent a plasma in a single impact cascade triggered by an electron of E 250 eV energy. This is important as it justifies the independent-electron approximation used in the model. At 1 fs, the (average) spatial distribution of secondary electrons is anisotropic with the electron cloud elongated in the direction of the primary impact. The maximal radius of the cascade is about 50 A at this time. As the system cools, energy is distributed more equally, and the spatial distribution of the electron cloud becomes isotropic. At 90 fs maximal radius is about 150 A. The Monte-Carlo model described here could be adopted for the investigation of radiation damage in other insulators and has implications for planned experiments with intense femtosecond X-ray sources.Comment: 26 pages, latex, 13 figure

Rare BB-Decays and Heavy to Light Semileptonic Transitions in the Isgur and Wise Limit

From the experimental branching ratios for $B^- --> \rho^0 l^-\bar\nu_l$ and D^+ --> {\overl K}^{*0}({\overl K}^0) e^+ \nu_e one finds, in the Heavy Quark Limit of $HQET$, $|V_{bu}|=(8.1\pm 1.7) x 10^{-3}$, larger but consistent with the actual quoted range $(2 - 7) x 10^{-3}$. In the same framework one predicts for $R(B --> K^*\gamma)=( 2 \pm 2 ) 10^{-2}$.Comment: 9 pages, 1 Figure avalaible on request from [email protected]

Associated Production of a Z Boson and a Single Heavy-Quark Jet

The leading-order process for the production of a Z boson and a heavy-quark jet at hadron colliders is gQ -> ZQ (Q=c,b). We calculate this cross section at next-to-leading order at the Tevatron and the LHC, and compare it with other sources of ZQ events. This process is a background to new physics, and can be used to measure the heavy-quark distribution function.Comment: 15 pages, 9 figures. Version to appear in Phys. Rev.

Sb-based low-noise avalanche photodiodes

Accurate detection of weak optical signals is a key function for a wide range of applications. A key performance parameter is the receiver signal-to-noise ratio, which depends on the noise of the photodetector and the following electrical circuitry. The circuit noise is typically larger than the noise of photodetectors that do not have internal gain. As a result, a detector that provides signal gain can achieve higher sensitivity. This is accomplished by increasing the photodetector gain until the noise associated with the gain mechanism is comparable to that of the output electrical circuit. For avalanche photodiodes (APDs), the noise that arises from the gain mechanism, impact ionization, increases with gain and depends on the material from which the APD is fabricated. Si APDs have established the state-of-the-art for low-noise gain for the past five decades. Recently, APDs fabricated from two Sb-based III-V compound quaternary materials, AlxIn1-xAsySb1-y and AlxGa1-xAsySb1-y, have achieved noise characteristics comparable to those of Si APDs with the added benefit that they can operate in the short-wave infrared (SWIR) and extended SWIR spectral regions. This paper describes the materials and device characteristics of these APDs and their performance in different spectral regions

Spacetime Supersymmetry in a nontrivial NS-NS Superstring Background

In this paper we consider superstring propagation in a nontrivial NS-NS background. We deform the world sheet stress tensor and supercurrent with an infinitesimal B_{\mu\nu} field. We construct the gauge-covariant super-Poincare generators in this background and show that the B_{\mu\nu} field spontaneously breaks spacetime supersymmetry. We find that the gauge-covariant spacetime momenta cease to commute with each other and with the spacetime supercharges. We construct a set of "magnetic" super-Poincare generators that are conserved for constant field strength H_{\mu\nu\lambda}, and show that these generators obey a "magnetic" extension of the ordinary supersymmetry algebra.Comment: 13 pages, Latex. Published versio

Relationship between dynamical heterogeneities and stretched exponential relaxation

We identify the dynamical heterogeneities as an essential prerequisite for stretched exponential relaxation in dynamically frustrated systems. This heterogeneity takes the form of ordered domains of finite but diverging lifetime for particles in atomic or molecular systems, or spin states in magnetic materials. At the onset of the dynamical heterogeneity, the distribution of time intervals spent in such domains or traps becomes stretched exponential at long time. We rigorously show that once this is the case, the autocorrelation function of the renewal process formed by these time intervals is also stretched exponential at long time.Comment: 8 pages, 4 figures, submitted to PR