Double-core evolution and the formation of neutron-star binaries with compact companions

We present the results of a systematic exploration of an alternative evolutionary scenario to form double neutron-star binaries, first proposed by Brown (1995), which does not involve a neutron star passing through a common envelope. In this scenario, the initial binary components have very similar masses, and both components have left the main sequence before they evolve into contact; preferably the primary has already developed a CO core. We have performed population synthesis simulations to study the formation of double neutron star binaries via this channel and to predict the orbital properties and system velocities of such systems. We obtain a merger rate for DNSs in this channel in the range of 0.1 - 12/Myr. These rates are still subject to substantial uncertainties such as the modelling of the contact phase.Comment: MNRAS, accepte

Horticultural marketing in Zimbabwe: problems met by smallholders and experience of the Mashonaland east fruit and vegetable project in addressing these

A research paper on impediments faced by rural small-scale horticultural producers in marketing their products and innovative ways used by some Zimbabwean rural farmers to address these.Communal area farmers, although traditional producers of horticultural crops, have failed to participate in the recent boom in horticulture. The horticultural marketing structure in Zimbabwe can be classified into two sectors, a formal sector with an emphasis on quality and grading standards which is market-driven, supplying supermarkets, hotels etc. and an informal sector which is product-driven and markets through the city municipal market, Mbare Musika and then through hawkers and vendors. The export market is effectively a new extension of the formal market and communal farmers who traditionally used the informal marketing chain therefore failed to gain access. The Mashonaland East Fruit and Vegetable project has provided infrastructure and technical support which has allowed small-scale (communal area) farmers entry into the formal marketing systems. The success attained so far is discussed and possibilities of small-scale farmers now growing crops for export considered

Multiband tunneling in trilayer graphene

The electronic tunneling properties of the two stable forms of trilayer graphene (TLG), rhombohedral ABC and Bernal ABA, are examined for pn and pnp junctions as realized by using a single gate (SG) or a double gate (DG). For the rhombohedral form, due to the chirality of the electrons, the Klein paradox is found at normal incidence for SG devices while at high energy interband scattering between additional propagation modes can occur. The electrons in Bernal ABA TLG can have a monolayer- or bilayer-like character when incident on a SG device. Using a DG however both propagation modes will couple by breaking the mirror symmetry of the system which induces intermode scattering and resonances that depend on the width of the DG pnp junction. For ABC TLG the DG opens up a band gap which suppresses Klein tunneling. The DG induces also an unexpected asymmetry in the tunneling angle for single valley electrons

Engaging the hard to engage : an examination of sanctioned TANF clients\u27 perceptions of the re-engagement process : a project done in collaboration with the Contra Costa County Employment and Human Services Department.

This mixed methods study examined the experiences and perceptions of welfare recipients who were referred to Contra Costa County\u27s sanctioned client outreach program. Contra Costa County assigned social workers ( Client Engagement Specialists ) to provide intensive outreach to this client population that was often regarded as difficult to engage in required employment activities and services. The objective was to better understand how welfare recipients viewed the attempt to re-engage them and what county-offered services they regarded as most helpful to them and their families. The study consisted of a sample of 19 respondents drawn from a larger sample pool of 149 sanctioned welfare recipients referred for services from October through August, 2008. Subjects answered questions from an interview guide consisting of 47 Likert Scale type questions and 4 open-ended questions regarding their experiences and beliefs. Additional data was obtained from the statewide CalWORKs data system used by Contra Costa County, CalWIN. Findings showed that sanctioned welfare recipients held largely positive views of their social workers and social workers\u27 attempts to engagement them in county employment services. They placed particular value on social worker competence in employment coaching, community resource referral and support. Respondents reported a high level of understanding of both welfare program requirements and the county noncompliance/sanction process. Attitudes toward county work experience and job readiness programs were mixed, with approximately half reporting positive experiences and half expressing dissatisfaction. In keeping with the previous literature, many recipients reported experiences of material hardship, mental health challenges and transportation problems. Spiritual beliefs were reported as a source of support by most respondents, however questions regarding specific beliefs/religious affiliations were not asked

Endothelial Dysfunction in Type 2 Diabetes: Targeting Inflammation

Several experimental and clinical studies have indicated a prominent role of vascular inflammation in the development of endothelial dysfunction. In endothelial dysfunction, the endothelium loses its physiological features, decrements nitric oxide bioavailability, and shifts towards a vasoconstrictor, pro-thrombotic and pro-inflammatory state. Within arterial wall, the interplay between the pro-inflammatory and pro-oxidant milieus promotes vascular dysfunction, and perivascular adipose tissue seems to play an important role. Inflammation is now considered a key event in vascular dysfunction and the development of vascular disease associated with obesity and type 2 diabetes. This concept is supported by the fact that anti-inflammatory adipokines such as adiponectin protect endothelial function, and interventions resulting in reduced inflammation such as the administration of salicylates prevent vascular dysfunction and cardiovascular events. Thus, the aim of this review is to address the role of inflammation and its mechanisms in endothelial dysfunction associated with diabetes, describing the impact of these conditions on vascular function

Development of an integrated heat pipe-thermal storage system for a solar receiver

The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low Earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the Earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at the potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube

Seismic strengthening of beam-column joints with multidirectional CFRP laminates

An experimental program was carried out to analyse the potentialities of a technique based on the use of multidirectional CFRP laminates (MDL-CFRP) for the seismic repair and strengthening of reinforced concrete (RC) beam-column joints. This experimental program comprises cyclic tests on three full-scale RC joints, representative of interior beam-column connections in buildings. The joints were initially submitted to a cyclic test inducing a damage pattern representative of a seismic event. Subsequently, they were repaired and strengthened with MDL-CFRP. The strengthened joints were then tested for the same loading history of the original ones up to their failure. The adopted strengthening technique uses the MDL-CFRP that are simultaneously glued and anchored to the concrete surfaces. This technique is called Mechanically Fastened and Externally Bonded Reinforcement (MF-EBR). In the present study, the effectiveness of two different strengthening configurations was investigated. The tests are described and the main results are presented and analyzed