190 research outputs found
Codes from adjacency matrices of uniform subset graphs
Studies of the p-ary codes from the adjacency matrices of uniform subset graphs Γ(n,k,r)Γ(n,k,r) and their reflexive associates have shown that a particular family of codes defined on the subsets are intimately related to the codes from these graphs. We describe these codes here and examine their relation to some particular classes of uniform subset graphs. In particular we include a complete analysis of the p-ary codes from Γ(n,3,r)Γ(n,3,r) for p≥5p≥5 , thus extending earlier results for p=2,3p=2,3
Managing formalization to increase global team effectiveness and meaningfulness of work in multinational organizations
Global teams may help to integrate across locations, and yet, with formalized rules and procedures, responsiveness to those locations’ effectiveness, and the team members’ experiences of work as meaningful may suffer. We employ a mixed-methods approach to understand how the level and content of formalization can be managed to resolve these tensions in multinationals. In a sample of global teams from a large mining and resources organization operating across 44 countries, interviews, observations, and a quantitative 2-wave survey revealed a great deal of variability between teams in how formalization processes were enacted. Only those formalization processes that promoted knowledge sharing were instrumental in improving team effectiveness. Implementing rules and procedures in the set-up of the teams and projects, rather than during interactions, and utilizing protocols to help establish the global team as a source of identity increased this knowledge sharing. Finally, we found members’ personal need for structure moderated the effect of team formalization on how meaningful individuals found their work within the team. These findings have significant implications for theory and practice in multinational organizations
Individualism and stock price crash risk
Employing a sample of 26,473 firms across 42 countries from 1990 to 2013, we find that firms located in countries with higher individualism have higher stock price crash risk. Furthermore, individualism can be transmitted by foreign investors from overseas markets to influence local firms’ crash risk, and can exacerbate the impact of firm risk taking and earnings management on crash risk. Moreover, the positive relation between individualism and crash risk is amplified during the global financial crisis and attenuated by enhanced country-level financial information transparency and the adoption of International Financial Reporting Standards
Heterogeneous patterns of tissue injury in NARP syndrome
Point mutations at m.8993T>C and m.8993T>G of the mtDNA ATPase 6 gene cause the neurogenic weakness, ataxia and retinitis pigmentosa (NARP) syndrome, a mitochondrial disorder characterized by retinal, central and peripheral neurodegeneration. We performed detailed neurological, neuropsychological and ophthalmological phenotyping of a mother and four daughters with NARP syndrome from the mtDNA m.8993T>C ATPase 6 mutation, including 3-T brain MRI, spectral domain optical coherence tomography (SD-OCT), adaptive optics scanning laser ophthalmoscopy (AOSLO), electromyography and nerve conduction studies (EMG-NCS) and formal neuropsychological testing. The degree of mutant heteroplasmy for the m.8993T>C mutation was evaluated by real-time allele refractory mutation system quantitative PCR of mtDNA from hair bulbs (ectoderm) and blood leukocytes (mesoderm). There were marked phenotypic differences between family members, even between individuals with the greatest degrees of ectodermal and mesodermal heteroplasmy. 3-T MRI revealed cerebellar atrophy and cystic and cavitary T2 hyperintensities in the basal ganglia. SD-OCT demonstrated similarly heterogeneous areas of neuronal and axonal loss in inner and outer retinal layers. AOSLO showed increased cone spacing due to photoreceptor loss. EMG-NCS revealed varying degrees of length-dependent sensorimotor axonal polyneuropathy. On formal neuropsychological testing, there were varying deficits in processing speed, visual–spatial functioning and verbal fluency and high rates of severe depression. Many of these cognitive deficits likely localize to cerebellar and/or basal ganglia dysfunction. High-resolution retinal and brain imaging in NARP syndrome revealed analogous patterns of tissue injury characterized by heterogeneous areas of neuronal loss
A retrospective and agenda for future research on Chinese outward foreign direct investment
Our original paper “The determinants of Chinese Outward Foreign Direct Investment” was the first
theoretically based empirical analysis of the phenomenon. It utilised internalisation theory to show that
Chinese state-owned firms reacted to home country market imperfections to surmount barriers to
foreign entry arising from naivety and the lack of obvious ownership advantages, leveraging
institutional factors including favourable policy stimuli. This special theory explained outward foreign
direct investment (OFDI) but provided surprises. These included the apparent appetite for risk evinced
by these early investors, causing us to conjecture that domestic market imperfections, particularly in
the domestic capital market, might be responsible. The article stimulated a massive subsequent, largely
successful, research effort on emerging country multinationals. In this Retrospective article we review
some of the main strands of research that ensued, for the insight they offer for the theme of our
commentary. Our theme is that theoretical development can only come through embracing yet more
challenging, different, and new contexts, and we make suggestions for future research directions
Gas flows, star formation and galaxy evolution
In the first part of this article we show how observations of the chemical
evolution of the Galaxy: G- and K-dwarf numbers as functions of metallicity,
and abundances of the light elements, D, Li, Be and B, in both stars and the
interstellar medium (ISM), lead to the conclusion that metal poor HI gas has
been accreting to the Galactic disc during the whole of its lifetime, and is
accreting today at a measurable rate, ~2 Msun per year across the full disc.
Estimates of the local star formation rate (SFR) using methods based on stellar
activity, support this picture. The best fits to all these data are for models
where the accretion rate is constant, or slowly rising with epoch. We explain
here how this conclusion, for a galaxy in a small bound group, is not in
conflict with graphs such as the Madau plot, which show that the universal SFR
has declined steadily from z=1 to the present day. We also show that a model in
which disc galaxies in general evolve by accreting major clouds of low
metallicity gas from their surroundings can explain many observations, notably
that the SFR for whole galaxies tends to show obvious variability, and
fractionally more for early than for late types, and yields lower dark to
baryonic matter ratios for large disc galaxies than for dwarfs. In the second
part of the article we use NGC 1530 as a template object, showing from
Fabry-Perot observations of its Halpha emission how strong shear in this
strongly barred galaxy acts to inhibit star formation, while compression acts
to stimulate it.Comment: 20 pages, 10 figures, to be presented at the "Penetrating Bars
through Masks of Cosmic Dust" conference in South Africa, proceedings
published by Kluwer, Eds. D.L. Block, K.C. Freeman, I. Puerari, & R. Groes
Understanding why women seek abortions in the US
BACKGROUND: The current political climate with regards to abortion in the US, along with the economic recession may be affecting women’s reasons for seeking abortion, warranting a new investigation into the reasons why women seek abortion. METHODS: Data for this study were drawn from baseline quantitative and qualitative data from the Turnaway Study, an ongoing, five-year, longitudinal study evaluating the health and socioeconomic consequences of receiving or being denied an abortion in the US. While the study has followed women for over two full years, it relies on the baseline data which were collected from 2008 through the end of 2010. The sample included 954 women from 30 abortion facilities across the US who responded to two open ended questions regarding the reasons why they wanted to terminate their pregnancy approximately one week after seeking an abortion. RESULTS: Women’s reasons for seeking an abortion fell into 11 broad themes. The predominant themes identified as reasons for seeking abortion included financial reasons (40%), timing (36%), partner related reasons (31%), and the need to focus on other children (29%). Most women reported multiple reasons for seeking an abortion crossing over several themes (64%). Using mixed effects multivariate logistic regression analyses, we identified the social and demographic predictors of the predominant themes women gave for seeking an abortion. CONCLUSIONS: Study findings demonstrate that the reasons women seek abortion are complex and interrelated, similar to those found in previous studies. While some women stated only one factor that contributed to their desire to terminate their pregnancies, others pointed to a myriad of factors that, cumulatively, resulted in their seeking abortion. As indicated by the differences we observed among women’s reasons by individual characteristics, women seek abortion for reasons related to their circumstances, including their socioeconomic status, age, health, parity and marital status. It is important that policy makers consider women’s motivations for choosing abortion, as decisions to support or oppose such legislation could have profound effects on the health, socioeconomic outcomes and life trajectories of women facing unwanted pregnancies
The influence of balanced and imbalanced resource supply on biodiversity – functioning relationship across ecosystems
Numerous studies show that increasing species richness leads to higher ecosystem productivity. This effect is often attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of resource supply and stoichiometry for biodiversity-ecosystem functioning relationships. Here, we merged theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We applied a structural equation model to define patterns of diversity-productivity relationships with respect to available resources. Meta-analysis was used to summarize the findings across ecosystem types ranging from aquatic ecosystems to grasslands and forests. As hypothesized, resource supply increased realized productivity and richness, but we found significant differences between ecosystems and study types. Increased richness was associated with increased productivity, although this effect was not seen in experiments. More even communities had lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduced ecosystem productivity. This synthesis, which integrates observational and experimental studies in a variety of ecosystems and geographical regions, exposes common patterns and differences in biodiversity-functioning relationships, and increases the mechanistic understanding of changes in ecosystems productivity
Expression of Tas1 Taste Receptors in Mammalian Spermatozoa: Functional Role of Tas1r1 in Regulating Basal Ca2+ and cAMP Concentrations in Spermatozoa
Background: During their transit through the female genital tract, sperm have to recognize and discriminate numerous chemical compounds. However, our current knowledge of the molecular identity of appropriate chemosensory receptor proteins in sperm is still rudimentary. Considering that members of the Tas1r family of taste receptors are able to discriminate between a broad diversity of hydrophilic chemosensory substances, the expression of taste receptors in mammalian spermatozoa was examined.
Methodology/Principal Findings:
The present manuscript documents that Tas1r1 and Tas1r3, which form the functional receptor for monosodium glutamate (umami) in taste buds on the tongue, are expressed in murine and human spermatozoa, where their localization is restricted to distinct segments of the flagellum and the acrosomal cap of the sperm head. Employing a Tas1r1-deficient mCherry reporter mouse strain, we found that Tas1r1 gene deletion resulted in spermatogenic abnormalities. In addition, a significant increase in spontaneous acrosomal reaction was observed in Tas1r1 null mutant sperm whereas acrosomal secretion triggered by isolated zona pellucida or the Ca2+ ionophore A23187 was not different from wild-type spermatozoa. Remarkably, cytosolic Ca2+ levels in freshly isolated Tas1r1-deficient sperm were significantly higher compared to wild-type cells. Moreover, a significantly higher basal cAMP concentration was detected in freshly isolated Tas1r1-deficient epididymal spermatozoa, whereas upon inhibition of phosphodiesterase or sperm capacitation, the amount of cAMP was not different between both genotypes.
Conclusions/Significance:
Since Ca2+ and cAMP control fundamental processes during the sequential process of fertilization, we propose that the identified taste receptors and coupled signaling cascades keep sperm in a chronically quiescent state until they arrive in the vicinity of the egg - either by constitutive receptor activity and/or by tonic receptor activation by gradients of diverse chemical compounds in different compartments of the female reproductive tract
Prospective investigation of risk factors for prostate cancer in the UK Biobank cohort study
Prostate cancer is the most common cancer in British men but its aetiology is not well understood. We aimed to identify risk factors for prostate cancer in British males.We studied 219 335 men from the UK Biobank study who were free from cancer at baseline. Exposure data were collected at recruitment. Prostate cancer risk by the different exposures was estimated using multivariable-adjusted Cox proportional hazards models.In all, 4575 incident cases of prostate cancer occurred during 5.6 years of follow-up. Prostate cancer risk was positively associated with the following: black ethnicity (hazard ratio black vs white=2.61, 95% confidence interval=2.10-3.24); having ever had a prostate-specific antigen test (1.31, 1.23-1.40); being diagnosed with an enlarged prostate (1.54, 1.38-1.71); and having a family history of prostate cancer (1.94, 1.77-2.13). Conversely, Asian ethnicity (Asian vs white hazard ratio=0.62, 0.47-0.83), excess adiposity (body mass index (⩾35 vs <25 kg m-2=0.75, 0.64-0.88) and body fat (⩾30.1 vs <20.5%=0.81, 0.73-0.89)), cigarette smoking (current vs never smokers=0.85, 0.77-0.95), having diabetes (0.70, 0.62-0.80), and never having had children (0.89, 0.81-0.97) or sexual intercourse (0.53, 0.33-0.84) were related to a lower risk.In this new large British prospective study, we identified associations with already-established, putative and possible novel risk factors for being diagnosed with prostate cancer. Future research will examine associations by tumour characteristics
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