Weakly Submodular Functions

Submodular functions are well-studied in combinatorial optimization, game theory and economics. The natural diminishing returns property makes them suitable for many applications. We study an extension of monotone submodular functions, which we call {\em weakly submodular functions}. Our extension includes some (mildly) supermodular functions. We show that several natural functions belong to this class and relate our class to some other recent submodular function extensions. We consider the optimization problem of maximizing a weakly submodular function subject to uniform and general matroid constraints. For a uniform matroid constraint, the "standard greedy algorithm" achieves a constant approximation ratio where the constant (experimentally) converges to 5.95 as the cardinality constraint increases. For a general matroid constraint, a simple local search algorithm achieves a constant approximation ratio where the constant (analytically) converges to 10.22 as the rank of the matroid increases

A survey of marine trash fish and fish meal as aquaculture feed ingredients in Vietnam

Livestock Production/Industries,

The ecology, biogeography, history and future of two globally important weeds : Cardiospermum halicacabum Linn. and C. grandiflorum Sw.

Members of the balloon vine genus, Cardiospermum, have been extensively moved around the globe as medicinal and horticultural species, two of which are now widespread invasive species; C. grandiflorum and C. halicacabum. A third species, C. corindum, may also have significant invasion potential. However, in some regions the native status of these species is not clear, hampering management. For example, in South Africa it is unknown whether C. halicacabum and C. corindum are native, and this is a major constraint to on-going biological control programmes against invasive C. grandiflorum. We review the geography, biology and ecology of selected members of the genus with an emphasis on the two most widespread invaders, C. halicacabum and C. grandiflorum. Specifically, we use molecular data to reconstruct a phylogeny of the group in order to shed light on the native ranges of C. halicacabum and C. corindum in southern Africa. Phylogenetic analyses indicate that southern African accessions of these species are closely related to South American taxa indicating human-mediated introduction and/or natural long distance dispersal. Then, on a global scale we use species distribution modelling to predict potential suitable climate regions where these species are currently absent. Native range data were used to test the accuracy with which bioclimatic modelling can identify the known invasive ranges of these species. Results show that Cardiospermum species have potential to spread further in already invaded or introduced regions in Australia, Africa and Asia, underlining the importance of resolving taxonomic uncertainties for future management efforts. Bioclimatic modelling predicts Australia to have highly favourable environmental conditions for C. corindum and therefore vigilance against this species should be high. Species distribution modelling showed that native range data over fit predicted suitable ranges, and that factors other than climate influence establishment potential. This review opens the door to better understand the global biogeography of the genus Cardiospermum, with direct implications for management, while also highlighting gaps in current research

The impact of endovascular treatment on cerebral aneurysm outcome at Groote Schuur Hospital

Objectives. Neuro-endovascular treatment was introduced at Groote Schuur Hospital in 2001. We sought to  assess whether this has resulted in a change in overall outcomes for patients treated for cerebral aneurysms.Design. Retrospective cohort study. The first cohort included cerebral aneurysm patients seen between 1994 and 1998 when only surgical treatment was available. The second cohort consisted of a group treated using both surgical and endovascular methods between 2002 and 2004.Subjects. Patients with ruptured and unruptured aneurysms were included in the study.Outcome measures. The Glasgow Outcome Score (GOS) was used to assess outcome. The primary  comparator between groups was major disability (GOS 3 and 2) and death (GOS 1)

Endovascular treatment of cerebral aneurysms - a cost analysis

Objectives. To determine if endovascular treatment of cerebral aneurysms is cost effective when  compared with conventional surgical treatment.Design. A retrospective study.Subjects. Seventeen patients treated between August 2002 and August 2003 had posterior communicating artery aneurysms. This group was selected for detailed analysis.Outcome measures. Total treatment costs, in South African rands (R), were calculated for each patient. Average treatment costs for each group were then compared.Results. Surgically clipped and endovascularly coiled groups were comparable for age, sex and clinical condition. The average cost for endovascular  treatment per patient was R37 041. Surgical treatment was more expensive at R44 104, a difference of 16%.Conclusions. Despite the high cost of endovascular devices, appropriate use of this technology ultimately  offers less expensive treatment than microsurgical clipping of aneurysms

Vietnamese American women’s beliefs and perceptions on cervical cancer, cervical cancer screening, and cancer prevention vaccines: A community-based participatory study

Cervical cancer remains commonly diagnosed in Vietnamese American women. Despite efforts to increase cervical cancer screening among Vietnamese American women, participation rates are persistently lower than the national goal. The objective of this study is to explore beliefs of Vietnamese American women about cervical cancer, cervical cancer screening, and cancer prevention vaccines. A qualitative descriptive investigation captured group perceptions about meaning and beliefs of cervical cancer, screening, and cancer prevention vaccines, and participants’ stories using a community-based participatory research approach. Forty Vietnamese American women were recruited from the Portland, Oregon metropolitan area into four focus groups. Using a process of directed content analysis, focus group transcripts were coded for themes. We found that cervical cancer continues to be a difficult topic to discuss, and Vietnamese American women may not bring the topic up themselves to their health care providers. Some women experienced intense emotions of fear or shame of having their cervix examined. Women delayed seeking cervical cancer screening and needed to have early warning signs, which guided them as to when to seek health care. Women focused on cleanliness through vaginal and/or perineal washing as primary prevention for cervical cancer. There were limited awareness and knowledge about cancer prevention vaccines, specifically the human papillomavirus. Some women relied heavily on their informal social networks of family, friends, or community for health knowledge. Fear and misunderstanding dominated the beliefs of Vietnamese American women about cervical cancer screening and prevention. These findings underscored the importance of having culturally-specific findings, which will inform a multicomponent intervention to promote cervical cancer screening and cancer prevention vaccine uptake within this population

Falling through the gaps: exploring the role of integrated commissioning in improving transition from children’s to adults' services for young people with long-term health conditions in England

Objectives: To explore the role of integrated commissioning in improving the transition of young people with longterm conditions from child to adult services. We aimed to identify organizational and policy gaps around transition services and provide recommendations for integrated commissioning practice. Methods: Semi-structured in-depth interviews were conducted with two groups of participants: (1) twenty-four stakeholders involved in the commissioning and provision of transition services for young people with long-term conditions in two regions in England; (2) five professionals with national roles in relation to planning for transition. Transcripts were interrogated using thematic analysis. Results: There is little evidence of integrated commissioning for transitional care for young people with long-term conditions. Commissioners perceive there to be a lack of national and local policy to guide integrated commissioning for transitional care; and limited resources for transition. Furthermore, commissioning organizations responsible for transition have different cultures, funding arrangements and related practices which make inter- and intra-agency co-ordination and cross-boundary continuity of care difficult to achieve. Conclusions: Integrated commissioning may be an effective way to achieve successful transitional care for young people with long-term health conditions. However, this innovative relational approach to commissioning requires a national steer together with recognition of common values and joint ownership between relevant stakeholders

Effect of Fluorine on Near-Liquidus Phase Equilibria of Basalts

Volatile species such as H2O, CO2, F, and Cl have significant impact in generation and differentiation of basaltic melts. Thus far experimental work has primarily focused on the effect of water and carbon dioxide on basalt crystallization, liquid-line of descent, and mantle melting [e.g., 1, 2] and the effects of halogens have received far less attention [3-4]. However, melts in the planetary interiors can have non-negligible chlorine and fluorine concentrations. Here, we explore the effects of fluorine on near-liquidus phase equilibria of basalt. We have conducted nominally anhydrous piston cylinder experiments using graphite capsules at 0.6 - 1.5 GPa on an Fe-rich model basalt composition. 1.75 wt% fluorine was added to the starting mix in the form of AgF2. Fluorine in the experimental glass was measured by SIMS and major elements of glass and minerals were analyzed by EPMA. Nominally volatile free experiments yield a liquidus temperature from 1330 C at 0.8GPa to 1400 at 1.6GPa and an olivine(Fo72)-pyroxene(En68)-liquid multiple saturation point at 1.25 GPa and 1375 C. The F-bearing experiments yield a liquiudus temperature from 1260 C at 0.6GPa to 1305 at 1.5GPa and an ol(Fo66)-pyx(En64)-MSP at 1 GPa and 1260 C. This shows that F depresses the basalt liquidus, extends the pyroxene stability field to lower pressure, and forces the liquidus phases to be more Fe-rich. KD(Fe-Mg/mineral-melt) calculated for both pyroxenes and olivines show an increase with increasing F content of the melt. Therefore, we infer that F complexes with Mg in the melt and thus increases the melt s silica activity, depressing the liquidus and changing the composition of the crystallizing minerals. Our study demonstrates that on a weight percent basis, the effect of fluorine is similar to the effect of H2O [1] and Cl [3] on freezing point depression of basalts. But on an atomic fraction basis, the effect of F on liquidus depression of basalts is xxxx compared to the effect of H. Future studies on kimberlitic and subduction zone magmas, which could have significant amount of fluorine, will need to consider the combined effects of F, Cl, and H on their stability and chemical evolution

Learnings from Vache du Faso

The Vache du Faso project aimed to improve milk production in Burkina Faso by crossbreeding local low-yielding zebu cattle with more productive dairy breeds through fixed-time artificial insemination (AI). This brief describes key lessons learned and factors for success to consider in the design and implementation of future projects