Polyhedral products over finite posets

Polyhedral products were defined by Bahri, Bendersky, Cohen and Gitler, to be spaces obtained as unions of certain product spaces indexed by the simplices of an abstract simplicial complex. In this paper we give a very general homotopy theoretic construction of polyhedral products over arbitrary pointed posets. We show that under certain restrictions on the poset \calp, that include all known cases, the cohomology of the resulting spaces can be computed as an inverse limit over \calp of the cohomology of the building blocks. This motivates the definition of an analogous algebraic construction - the polyhedral tensor product. We show that for a large family of posets, the cohomology of the polyhedral product is given by the polyhedral tensor product. We then restrict attention to polyhedral posets, a family of posets that include face posets of simplicial complexes, and simplicial posets, as well as many others. We define the Stanley-Reisner ring of a polyhedral poset and show that, like in the classical cases, these rings occur as the cohomology of certain polyhedral products over the poset in question. For any pointed poset \calp we construct a simplicial poset s(\calp), and show that if \calp is a polyhedral poset then polyhedral products over \calp coincide up to homotopy with the corresponding polyhedral products over s(\calp).Comment: 32 page

Computing a rectilinear shortest path amid splinegons in plane

We reduce the problem of computing a rectilinear shortest path between two given points s and t in the splinegonal domain \calS to the problem of computing a rectilinear shortest path between two points in the polygonal domain. As part of this, we define a polygonal domain \calP from \calS and transform a rectilinear shortest path computed in \calP to a path between s and t amid splinegon obstacles in \calS. When \calS comprises of h pairwise disjoint splinegons with a total of n vertices, excluding the time to compute a rectilinear shortest path amid polygons in \calP, our reduction algorithm takes O(n + h \lg{n}) time. For the special case of \calS comprising of concave-in splinegons, we have devised another algorithm in which the reduction procedure does not rely on the structures used in the algorithm to compute a rectilinear shortest path in polygonal domain. As part of these, we have characterized few of the properties of rectilinear shortest paths amid splinegons which could be of independent interest

Tunicamycin induced inhibition of calpain 1 and 2 enzyme activity in ovarian cancer cells

Background: Tunicamycin (TN) is an antitumor agent and induced intracellular calcium levels in many cells, however its molecular mechanism is still needed to be explored. Calpeptin (Calp) is an inhibitor of both calpain 1 and 2 (CAPN-1/2) enzymes, and plays a fundamental role in tumor mechanism. In this study, the effects of TN and Calp were investigated on CAPN-1/2 enzyme activity in normal and ovarian cancer cells adhered to fibronectin. Methods: 24uM TN, 50uM Calp, and combined TN and Calp (TN+Calp) were applied for 1 and 12 hours to FN-bound (FN+) and non-FN-bound (FN-) normal human ovarian epithelial (IHOSE) and ovarian cancer (SKOV-3) cells. The activation of CAPN-1/2 was measured by the luminescent method and the significance of the results was analyzed with the t-test. Results: CAPN-1/2 enzyme activity (at 12 hour) was present in both cell lines, but the level of enzyme is higher in IHOSE cells compared to SKOV-3 cells. The results showed that 1 hour TN and TN+Calp applications stimulated CAPN-1/2 enzyme activity in IHOSE cells but did not show any stimulating effect in SKOV-3 cells. After 12-hour of treatment, the cells with TN, Calp or TN+Calp showed an inhibitory effect on CAPN-1/2 enzyme in both FN+IHOSE and SKOV-3 cells. At 12-hour TN+Calp administration was determined to be the most effective inhibitor in FN+ SKOV-3 since it inhibited CAPN1/2 activity statistically significantly more than both Calp and TN administrations. Conclusions: The effects of TN, Calp and TN+Calp applications on the CAPN-1/2 enzyme varied according to the cell type, normal or cancer cells, and whether the cell was bound to FN and the incubation period. 12 h administrations of TN, Calp or TN+Calp inhibited the CAPN-1/2 enzyme in both FN+ IHOSE and SKOV-3 cells

Isolated learners from diverse language backgrounds in the mainstream primary classroom: A sociocultural perspective

This paper focuses on the linguistic and cultural (‘languaculture’, Agar, 1994) challenges faced by learners from diverse language backgrounds (DLB) in New Zealand schools. It describes the typical learning context in primary classrooms terms of interactional, instructional, and cognitive dimensions. It then presents vignettes of four DLB learners and explains their relative competence in terms of Cummin’s (1981) distinction between BICS and CALP (Basic Interactional Communication Skills and Cognitive-Academic Language Proficiency). It goes on to discuss the extent to which such proficiency is the result of linguistic and cultural distance, and how that distance might be bridged by applying key constructs from sociocultural theory, and the implementation of Individual Languaculture Plans for DLB learners. The paper concludes with discussing the issue of where responsibility lies for coping with the challenges face by DLB learners

Study on cash transfers for seed security in humanitarian settings

This study examines the barriers and opportunities for cash transfers to be used to address seed security in humanitarian situations. Cash, while not a new approach, has gained momentum in recent years, especially with the emergence of the Cash Learning Partnership (CaLP) and humanitarian organizations’ commitments through the Grand Bargain.2 Historically, direct seed distribution (DSD) has dominated agricultural responses in emergencies. While effective in many situations, other modalities of addressing farmers’ needs have also proven to be effective, including seed and voucher fairs and, increasingly, cash transfer responses. The latter response typically provides farmers greater choices to make decisions about their seed needs and preferences. However, as with direct distribution and vouchers, cash can be a viable option but may not always be appropriate in every situation. The quality of seed is of paramount importance in choosing a response and has been an ongoing (and often contentious and political) discussion for decades. The results of this study advocate for a multi- stakeholder perspective on the quality of seed, while offering farmers the most flexible and most appropriate response possible for their given situation. In some cases, this will be cash transfers, but certainly not in all cases. A range of options offers the best chance for a successful, responsive, and appropriate program. The evidence base on outcomes from using cash for seed in humanitarian contexts is limited, however, reviewing a series of examples shows the breadth and range of options that are being explored. The cases from an array of organizations and countries including Iraq, Ethiopia, Nigeria, Uganda, Zambia, Zimbabwe, Malawi, Madagascar, and Guatemala, show that understanding the context is key to the response analysis and the choice of modality. Organizational approaches and previous experience also played a role in the choice of modality. The evidence to date shows that cash, in addition to complementary programming such as technical or business training, offers promise for seed security interventions. In addition, initiatives to support both the demand and supply side of the market have proven to be effective. Key findings include: 1. Market and needs assessments must include a seed component or SSSA to ensure a response designed to address the right problem, not the assumption. For markets, both informal and formal seed markets need to be included. 2. Good needs assessments, response analysis and program design help ensure participants’ spending cash on what implementers anticipate they will. 3. Program participants’ preferences on modalities are not consistently included in response analysis. 4. Mixed modalities (cash and vouchers, or cash and DSD) can broaden crop choices. 5. Quality screenings for seed are taking place; the quality of seed is important to organizations and project participants. 6. Cash for seed security interventions are limited, but growing in prevalence. 7. Providing cash plus complementary support is a promising practice for fostering seed security. 8. The nexus between relief and development is critical—designing projects with a longer-term development view: cash can prepare the way for farmers to continue true market engagement post-relief, spur business development in subsequent seasons, and offer opportunities for financial inclusion. 9. Supporting supply side to bring quality seed markets ‘closer’ to project participants should be considered along with demand-side interventions (cash, voucher and other). 10. Investment in preparedness provides a better foundation to implement impactful cash for seed security response. The risks, mitigating actions, opportunities and enablers for cash and seed security response are also explored. The study concludes with actionable and practical recommendations for further advancing the evidence base, as well as implementation suggestions. Continuous collaboration of key stakeholders in seed systems is essential to advance the discussions and action on the way forward with cash and seed systems