Tree size but not forest basal area influences ant colony response to disturbance in a neotropical ant–plant association

Ant–acacia mutualisms are conspicuous biotic associations in Savannah and neotropical ecosystems; however, the effects of tree size and forest structure on ant behaviour and tree traits are rarely examined. We tested two hypotheses related to these effects: (1) ant responses to disturbance are influenced by tree size and forest basal area; and (2) tree traits important to ants are predictable by tree size and forest basal area. We investigated these hypotheses in a dry tropical forest (Ometepe Island, Nicaragua) with the myrmecophytic Collins acacia (Vachellia collinsii Saff.) and the ant Pseudomyrmex spinicola (Emery 1890). We measured trees from three size classes and three basal area classes and quantified resources that are important for ants, including food resources (nectaries and Beltian bodies) and domiciles (thorns), as well as a measure of potential tree reproductive fitness (seedpods). We also evaluated ant responses to experimental disturbances. Three important findings emerged: (1) on average, 1140–1173% more ants responded to experimental disturbances of large trees than small- or intermediate-sized trees, respectively; (2) forest basal area did not affect ant responses to disturbance; and (3) neither tree size nor forest basal area was correlated with branch-level mean numbers of nectaries, food bodies or thorns. Our studies support the hypothesis that tree size is an important factor regarding ant behavioural responses to disturbance, but not forest basal area. Our work suggests that future studies of ant behaviour on myrmecophytes should consider tree size

Negative Equity and Foreclosure: Theory and Evidence

Millions of Americans have negative housing equity, meaning that the outstanding balance on their mortgage exceeds their home's current market value. Our data show that the overwhelming majority of these households will not lose their homes. Our finding is consistent with historical evidence: we examine more than 100,000 homeowners in Massachusetts who had negative equity during the early 1990s and find that fewer than 10 percent of these owners eventually lost their home to foreclosure. This result is also, contrary to popular belief, completely consistent with economic theory, which predicts that from the borrower's perspective, negative equity is a necessary but not a sufficient condition for foreclosure. Our findings imply that lenders and policymakers face a serious information problem in trying to help borrowers with negative equity, because it is difficult to determine which borrowers actually require help in order to prevent the loss of their homes to foreclosure

Puberty in breeds of female hair sheep in Northeast Brazil.

Abstract: The variation in the onset of puberty in ewe lambs is influenced by both genetic and environmental factors. Identification of the specific factor and its influence in relation to other factors is unclear. The age and live body weight at which ewe lambs show the first puberal estrus are of considerable practical importance. Ewe lambs showing early sexual activity have increased lifetime performance and hada higher reproductive efficiency in the adult ewe. An attempt has been made to study puberty in terms of age, live body weight, breed and ovarian activity at the onset of puberty (first behavioral estrus) of hair sheep in Northeast Brazil. [Puberdade em fêmeas de raças ovinas deslanadas no Nordeste do Brasil]. Resumo: Analisou-se o desempenho de 112 borregas Morada Nova (32), Somalis Brasileira (63) e Santa Inês (17), mantidas em pastagem nativa, no Centro Nacional de Pesquisa de Caprinos (CNPC), em Sobral, CE, Nordeste do Brasil (latitude 3° 42' Sul e longitude em 40° 21' Oeste). Desmamadas a idade média de 112 dias, foram pesadas ao nascer e a cada 28 dias, até à puberdade e observadas com vistas à detecção da ocorrência de estro, durante duas vezes ao dia, com auxílio de rufiões. Entre 40 e 60 horas após a borrega ser identificada em estro, era submetida à laparotomia, como objetivo de se avaliar a função ovariana quanto à ocorrência e à taxa de ovulação nos períodos pré-puberal e puberal. A idade e o peso médio à puberdade foram de 306,3 ± 5,6 dias e de 20,7 ± 0,3 kg, respectivamente. A raça Santa Inês (24,0 ± 1,0 kg) foi estatisticamente mais pesada (P 0,05), porém observou-se efeito de ano (P 0,05) entre raças. Durante o período pré-puberal, 78,35% das borregas ovularam com uma taxa de 1,13

Puberty in four genotypes of female goats in Northeast Brazil.

Abstract: This experiment was carried out with 99 female kids from four native brceds (Canind& Marota, Moxotó, and Repartida, raised on native pasture at Lhe l3razilian National (loat Research Center, Ceará State, Northeast Brazil. Body weight of the animais were taken at birth, and at four-week intervais until each female kid showed the first puberal estrus. Between 40-60 hours after puberal estrus was detected using teaser bucks, the ovaries of each female kid were observed by laparotomy to determine the number of corpora albicantia and/or corpora hemorrhagica, as an estimate of the occurrence and rate of prepuberal and puberal ovulation, respectively. The overail mean age and live body weight at puberty was 3616±69 days and 12.6±0.2 kg, respectively. I3reed or type of birth did not affect sigrnficaniiy (P>0.05) the age and weight at puberty. The ovulation rate at prepuberal period and at puberal estrus was 1.00 and 1.04, respcctively (P>0.05). Forty percent of the female kids ovulated prior to puberal estrus and 100% ovulated at puberal estrus. Ovulation occurred more frequentely m the right than iii the Ieft ovary at prepuberal (P0,05) a idade e o peso a puberdade. As taxas medias de ovulacao, no periodo pre-puberal e a puberdade, foram 1,00 e 1,04, respectivamente (P>0,05). Aproximadamente 40,0% das cabritas tinham ovulado antes de apresentarem o primeiro estro clinico, enquanto 100,0% delas ovularam a puberdade. A ovulacao ocorreu com maior frequencia no ovario direito do que no esquerdo, no periodo pre-puberal (P<0,01) e a puberdade (P<0,05)

Microfabricated devices for performing chemical and biochemical analysis

There is growing interest in microfabricated devices that perform chemical and biochemical analysis. The general goal is to use microfabrication tools to construct miniature devices that can perform a complete analysis starting with an unprocessed sample. Such devices have been referred to as lab-on-a-chip devices. Initial efforts on microfluidic laboratory-on-a-chip devices focused on chemical separations. There are many potential applications of these fluidic microchip devices. Some applications such as chemical process control or environmental monitoring would require that a chip be used over an extended period of time or for many analyses. Other applications such as forensics, clinical diagnostics, and genetic diagnostics would employ the chip devices as single use disposable devices

Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami)

Sexual differentiation across taxa may be due to genetic sex determination (GSD) and/or temperature sex determination (TSD). In many mammals, males are heterogametic (XY); whereas females are homogametic (XX). In most birds, the opposite is the case with females being heterogametic (ZW) and males the homogametic sex (ZZ). Many reptile spe- cies lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps). There has been speculation that Australian Brush-turkeys (Alectura lathami) exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP) and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Austra- lian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae

Muddled Boundaries of Digital Shrines

International audienceBased on an online ethnography study of 274 YouTube videos posted during the Virginia Tech or the Newtown massacres, this article discusses how users resort to participatory media during such mediatized events to create a digital spontaneous shrine. The assemblage of this sanctuary on a website hosting billions of user-generated contents is made possible by means of folksonomy and website architecture, and a two-fold social dynamic based on participatory commitment and the institutionalization of a collective entity. Unlike “physical” spontaneous shrines erected in public spaces, these digital shrines connect the bereaved with provocative or outrageous contributions, notably tributes from school shooting fans using participatory media to commemorate the killer’s memory. This side effect, generated by the technical properties of the platform, compromises the tranquility of the memorial and muddles the boundaries and the contents of such sanctuaries

Nutritional adequacy of a cows’ milk exclusion diet in infancy

BACKGROUND: Infants with suspected cows’ milk allergy are required to follow a strict milk exclusion diet which may lead to nutritional deficiencies, especially if not supervised by a healthcare professional. The aim of this study was to assess the nutritional adequacy of a cows’ milk exclusion diet in a group of UK infants over a period of 6 months. METHODS: Participants in this study are a subgroup of the Prevalence of Infant Food Allergy study, a prospective food allergy birth cohort study from the South of England. Each infant consuming a milk free diet, following advice from a specialist allergy dietitian, was matched to two control infants who were consuming an unrestricted diet, forming a nested matched case–control study. Detailed food diaries completed prospectively for 1 week per month over a 5 month period, were coded and analysed according to a standard protocol. RESULTS: The diets of 39 infants (13 milk-free and 26 controls) were assessed. Mean age at diet commencement was 14 weeks. Two of the eleven infants started on an extensively hydrolysed formula did not tolerate it and required an amino acid formula for symptom resolution. All infants had mean intakes in excess of the estimated average requirement for energy and the recommended nutrient intake (RNI) for protein, calcium, iron, selenium, zinc, vitamins A, C and E. Vitamin D intake was in excess of the RNI at all time-points, except at 44 weeks of age. Across the study period, selenium intake was higher for infants consuming a milk free diet whilst vitamin C intake was higher for infants consuming an unrestricted diet. Differences were found between the two groups for protein, calcium, iron and vitamin E intakes at differing time points. CONCLUSION: This study demonstrated that although infants consuming a milk-free diet have a nutritional intake that is significantly different to matched controls who are eating an unrestricted diet, this difference is not constant and it is not seen for all nutrients. Further research in infants without dietetic input is needed to explore the nutritional implications of unsupervised cows’ milk exclusion diets

Perception of nonnative tonal contrasts by Mandarin-English and English-Mandarin sequential bilinguals

This study examined the role of acquisition order and crosslinguistic similarity in influencing transfer at the initial stage of perceptually acquiring a tonal third language (L3). Perception of tones in Yoruba and Thai was tested in adult sequential bilinguals representing three different first (L1) and second language (L2) backgrounds: L1 Mandarin-L2 English (MEBs), L1 English-L2 Mandarin (EMBs), and L1 English-L2 intonational/non-tonal (EIBs). MEBs outperformed EMBs and EIBs in discriminating L3 tonal contrasts in both languages, while EMBs showed a small advantage over EIBs on Yoruba. All groups showed better overall discrimination in Thai than Yoruba, but group differences were more robust in Yoruba. MEBs’ and EMBs’ poor discrimination of certain L3 contrasts was further reflected in the L3 tones being perceived as similar to the same Mandarin tone; however, EIBs, with no knowledge of Mandarin, showed many of the same similarity judgments. These findings thus suggest that L1 tonal experience has a particularly facilitative effect in L3 tone perception, but there is also a facilitative effect of L2 tonal experience. Further, crosslinguistic perceptual similarity between L1/L2 and L3 tones, as well as acoustic similarity between different L3 tones, play a significant role at this early stage of L3 tone acquisition.Published versio

The Exomars Climate Sounder (EMCS) Investigation

The ExoMars Climate Sounder (EMCS) investigation is developed at the Jet Propulsion Laboratory (Principal Investigator J. T. Schofield) in collaboration with an international scientific team from France, the United Kingdom and the USA. EMCS plans to map daily, global, pole-to-pole profiles of temperature, dust, water and CO2 ices, and water vapor from the proposed 2016 ExoMars Trace Gas Orbiter (EMTGO). These profiles are to be assimilated into Mars General Circulation Models (MGCMs) to generate global, interpolated fields of measured and derived parameters such as wind