1,593 research outputs found
A Role for Actin, Cdc1p, and Myo2p in the Inheritance of Late Golgi Elements in \u3cem\u3eSaccharomyces cerevisiae\u3c/em\u3e
In Saccharomyces cerevisiae, Golgi elements are present in the bud very early in the cell cycle. We have analyzed this Golgi inheritance process using fluorescence microscopy and genetics. In rapidly growing cells, late Golgi elements show an actin-dependent concentration at sites of polarized growth. Late Golgi elements are apparently transported into the bud along actin cables and are also retained in the bud by a mechanism that may involve actin. A visual screen for mutants defective in the inheritance of late Golgi elements yielded multiple alleles of CDC1. Mutations in CDC1 severely depolarize the actin cytoskeleton, and these mutations prevent late Golgi elements from being retained in the bud. The efficient localization of late Golgi elements to the bud requires the type V myosin Myo2p, further suggesting that actin plays a role in Golgi inheritance. Surprisingly, early and late Golgi elements are inherited by different pathways, with early Golgi elements localizing to the bud in a Cdc1p- and Myo2p-independent manner. We propose that early Golgi elements arise from ER membranes that are present in the bud. These two pathways of Golgi inheritance in S. cerevisiae resemble Golgi inheritance pathways in vertebrate cells
Sampling Plans for Control-Inspection Schemes Under Independent and Dependent Sampling Designs With Applications to Photovoltaics
The evaluation of produced items at the time of delivery is, in practice,
usually amended by at least one inspection at later time points. We extend the
methodology of acceptance sampling for variables for arbitrary unknown
distributions when additional sampling infor- mation is available to such
settings. Based on appropriate approximations of the operating characteristic,
we derive new acceptance sampling plans that control the overall operating
characteristic. The results cover the case of independent sampling as well as
the case of dependent sampling. In particular, we study a modified panel
sampling design and the case of spatial batch sampling. The latter is advisable
in photovoltaic field monitoring studies, since it allows to detect and analyze
local clusters of degraded or damaged modules. Some finite sample properties
are examined by a simulation study, focusing on the accuracy of estimation
The on-top pair-correlation density in the homogeneous electron liquid
The ladder theory, in which the Bethe-Goldstone equation for the effective
potential between two scattering particles plays a central role, is well known
for its satisfactory description of the short-range correlations in the
homogeneous electron liquid. By solving exactly the Bethe-Goldstone equation in
the limit of large transfer momentum between two scattering particles, we
obtain accurate results for the on-top pair-correlation density , in both
three dimensions and two dimensions. Furthermore, we prove, in general, the
ladder theory satisfies the cusp condition for the pair-correlation density
at zero distance .Comment: 8 pages, 4 figure
Why does the ethnic and socio-economic composition of schools influence math achievement? The role of sense of futility and futility culture
Although a number of studies in many countries have investigated the impact of the ethnic and socio-economic composition of schools on academic performance, few studies have analyzed in detail how and why compositional features matter. This article presents an examination of whether pupils’ sense of futility and schools’ futility culture account for the impact of ethnic and socio-economic status (SES) composition of schools on the academic achievement of their pupils. Multilevel analyses of data based on a survey of 2,845 pupils (aged 10–12 years) in 68 Flemish primary schools revealed that higher proportions of immigrant and working-class pupils in a school is associated with lower levels of math achievement in both immigrant and native Belgian pupils. However, by analyzing at a deeper level, by taking control variables into account, our study found that the ethnic composition of the school no longer had a significant effect on pupils’ achievement, while the SES composition still did. Most importantly, our results indicated that the remaining impact of SES composition can be explained by pupils’ sense of futility and schools’ futility culture. The implications of these findings for educational policy are discussed
Going to scale: design and implementation challenges of a program to increase access to skilled birth attendants in Nigeria
This is the final version. Available from BMC via the DOI in this record.Background: The lack of availability of skilled providers in low- and middle- income countries is considered to be an important barrier to achieving reductions in maternal and child mortality. However, there is limited research on programs increasing the availability of skilled birth attendants in developing countries. We study the implementation of the Nigeria Midwives Service Scheme, a government program that recruited and deployed nearly 2,500 midwives to rural primary health care facilities across Nigeria in 2010. An outcome evaluation carried out by this team found only a modest impact on the use of antenatal care and no measurable impact on skilled birth attendance. This paper draws on perspectives of policymakers, program midwives, and community residents to understand why the program failed to have the desired impact. Methods: We conducted semi-structured interviews with federal, state and local government policy makers and with MSS midwives. We also conducted focus groups with community stakeholders including community leaders and male and female residents. Results: Our data reveal a range of design, implementation and operational challenges ranging from insufficient buy-in by key stakeholders at state and local levels, to irregular and in some cases total non-provision of agreed midwife benefits that likely contributed to the program’s lack of impact. These challenges not only created a deep sense of dissatisfaction with the program but also had practical impacts on service delivery likely affecting households’ uptake of services. Conclusion: This paper highlights the challenge of effectively scaling up maternal and child health interventions. Our findings emphasize the critical importance of program design, particularly when programs are implemented at scale; the need to identify and involve key stakeholders during planning and implementation; the importance of clearly defining lines of authority and responsibility that align with existing structures; and the necessity for multi-faceted interventions that address multiple barriers at the same time.International Initiative for Impact Evaluatio
Ambivalence toward men: comparing sexism among Polish, South African and British university students
This study extends the literature on attitudes toward gender roles by exploring whether the nature of sexism (i.e., benevolence and hostility directed at men) differs among university students from two under-researched countries, Poland (n = 190) and South Africa (n = 188), in a comparison with students in the United Kingdom (n = 166). Based on empirical literature applying Ambivalent Sexism Theory, and in the light of the socio-political context, it was hypothesized that: (1) both hostile and benevolent attitudes toward men in Poland would be more liberal than in South Africa and more conservative than in the United Kingdom, and (2), women would exhibit more hostile but less benevolent attitudes than men in relatively more conservative South Africa. The Ambivalence to Men Inventory was used to measure the two types of sexist attitudes about men. Findings supported the first hypothesis for hostile attitudes and partially for benevolent attitudes. South African and Polish students were more benevolent and hostile to men than British students, and students from South Africa were more hostile than those from Poland. Moreover, as predicted, a significant country-by-gender interaction revealed that South African women had more hostile and less benevolent attitudes to men than South African men. No such gender gap was present in the case of hostile attitudes in Poland and benevolent attitudes in the United Kingdom. Findings are discussed in terms of Ambivalent Sexism Theory and the countries’ socio-cultural context
Current-density functional theory of time-dependent linear response in quantal fluids: recent progress
Vignale and Kohn have recently formulated a local density approximation to
the time-dependent linear response of an inhomogeneous electron system in terms
of a vector potential for exchange and correlation. The vector potential
depends on the induced current density through spectral kernels to be evaluated
on the homogeneous electron-gas. After a brief review of their theory, the case
of inhomogeneous Bose superfluids is considered, with main focus on dynamic
Kohn-Sham equations for the condensate in the linear response regime and on
quantal generalized hydrodynamic equations in the weak inhomogeneity limit. We
also present the results of calculations of the exchange-correlation spectra in
both electron and superfluid boson systems.Comment: 12 pages, 2 figures, Postscript fil
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