The effects of estimation of censoring, truncation, transformation and partial data vectors

The purpose of this research was to attack statistical problems concerning the estimation of distributions for purposes of predicting and measuring assembly performance as it appears in biological and physical situations. Various statistical procedures were proposed to attack problems of this sort, that is, to produce the statistical distributions of the outcomes of biological and physical situations which, employ characteristics measured on constituent parts. The techniques are described

Wage and Occupational Differences Between Black and White Men: Labor Market Discrimination in the Rural South

The existence of labor market discrimination based on race is well established.However, study continues into a variety of aspects of discrimination-among them the extent to which it exists in different regions. Gwartney has estimated the ratio of black to white earnings to be between .83 and .88 for the North and between .68 and .74 for the South. Masters, in a study of earnings differentials between black and white men, found a ratio of .79 for the non-South and .69 for the South. Although considerable literature has developed concerning earnings differentials, wage discrimination in rural areas is one topic which has received relatively little attention. In an attempt to eliminate this oversight this paper concentrates on the extent of wage differences between black and white men in the rural South attributable to labor market discrimination

Assessment of mechanical properties and microstructure characterizing techniques in their ability to quantify amount of cold work in 316l alloy

Stress corrosion cracking (SCC) behavior is a matter of concern for structural materials, namely, stainless steels and nickel alloys, in nuclear power plants. High levels of cold work (CW) have shown to both reduce crack initiation times and increase crack growth rates. Cold working has numerous effects on a material, including changes in microstructure, mechanical properties, and residual stress state, yet it is typically reported as a simple percent change in geometry. There is need to develop a strategy for quantitative assessment of cold-work level in order to better understand stress corrosion cracking test data. Five assessment techniques, commonly performed alongside stress corrosion cracking testing (optical microscopy (OM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), tensile testing, and hardness testing) are evaluated with respect to their ability to quantify the level of CW in a component. The test material is stainless steel 316L that has been cold-rolled to three conditions: 0%, 20%, and 30% CW. Measurement results for each assessment method include correlation with CW condition and repeatability data. Measured values showed significant spatial variation, illustrating that CW level is not uniform throughout a component. Mechanical properties (tensile testing, hardness) were found to correlate most linearly with the amount of imparted CW

Women's experiences of pregnancy, childbirth, and the postnatal period in the Gambia: A qualitative study

Objective: In sub-Saharan African countries, there are unique cultural factors and adverse physical conditions that contribute to women's experiences of pregnancy and birth. The objective of this study was to qualitatively explore women's experiences of pregnancy, childbirth, the postnatal period, and maternal psychological distress in The Gambia. Design and methods: Semi-structured interviews were carried out with 55 women who had given birth within the previous year. Results: Thematic analysis identified five themes: (1) transition to adulthood, (2) physical difficulties, (3) value of children in relation to others, (4) children as a strain, and (5) going through it alone. The results suggest that having a child is a defining point in women's lives associated with happiness and joy. However, women also described situations which could lead to unhappiness and distress in the perinatal period. A child conceived out of wedlock or a baby girl can be sources of distress because of negative cultural perceptions. The strain of having a child, particularly the additional financial burden, and minimal support from men were also a concern for women. Finally, women recognized the danger associated with delivery and expressed recurrent worries of complications during childbirth which could result in the death of them or the baby. Conclusions: Further research is needed to identify women vulnerable to psychological distress so that health services and target interventions can be developed accordingly

Local density of states of electron-crystal phases in graphene in the quantum Hall regime

We calculate, within a self-consistent Hartree-Fock approximation, the local density of states for different electron crystals in graphene subject to a strong magnetic field. We investigate both the Wigner crystal and bubble crystals with M_e electrons per lattice site. The total density of states consists of several pronounced peaks, the number of which in the negative energy range coincides with the number of electrons M_e per lattice site, as for the case of electron-solid phases in the conventional two-dimensional electron gas. Analyzing the local density of states at the peak energies, we find particular scaling properties of the density patterns if one fixes the ratio nu_N/M_e between the filling factor nu_N of the last partially filled Landau level and the number of electrons per bubble. Although the total density profile depends explicitly on M_e, the local density of states of the lowest peaks turns out to be identical regardless the number of electrons M_e. Whereas these electron-solid phases are reminiscent to those expected in the conventional two-dimensional electron gas in GaAs heterostructures in the quantum Hall regime, the local density of states and the scaling relations we highlight in this paper may be, in graphene, directly measured by spectroscopic means, such as e.g. scanning tunneling microscopy.Comment: 8 pages, 7 figures; minor correction

Systematic limits on sin^2{2theta_{13}} in neutrino oscillation experiments with multi-reactors

Sensitivities to sin^2{2theta_{13}} without statistical errors (``systematic limit'') are investigated in neutrino oscillation experiments with multiple reactors. Using an analytical approach, we show that the systematic limit on sin^2{2theta_{13}} is dominated by the uncorrelated systematic error sigma_u of the detector. Even in an experiment with multi-detectors and multi-reactors, it turns out that most of the systematic errors including the one due to the nature of multiple sources is canceled as in the case with a single reactor plus two detectors, if the near detectors are placed suitably. The case of the KASKA plan (7 reactors and 3 detectors) is investigated in detail, and it is explicitly shown that it does not suffer from the extra uncertainty due to multiple reactors.Comment: 26 pages, 10 eps-files, revtex

Structural lubricity: Role of dimension and symmetry

When two chemically passivated solids are brought into contact, interfacial interactions between the solids compete with intrabulk elastic forces. The relative importance of these interactions, which are length-scale dependent, will be estimated using scaling arguments. If elastic interactions dominate on all length scales, solids will move as essentially rigid objects. This would imply superlow kinetic friction in UHV, provided wear was absent. The results of the scaling study depend on the symmetry of the surfaces and the dimensionalities of interface and solids. Some examples are discussed explicitly such as contacts between disordered three-dimensional solids and linear bearings realized from multiwall carbon nanotubes.Comment: 7 pages, 1 figur

Kinematic and Thermal Structure at the onset of high-mass star formation

We want to understand the kinematic and thermal properties of young massive gas clumps prior to and at the earliest evolutionary stages of high-mass star formation. Do we find signatures of gravitational collapse? Do we find temperature gradients in the vicinity or absence of infrared emission sources? Do we find coherent velocity structures toward the center of the dense and cold gas clumps? To determine kinematics and gas temperatures, we used ammonia, because it is known to be a good tracer and thermometer of dense gas. We observed the NH$_3$(1,1) and (2,2) lines within seven very young high-mass star-forming regions with the VLA and the Effelsberg 100m telescope. This allows us to study velocity structures, linewidths, and gas temperatures at high spatial resolution of 3-5$"$, corresponding to $\sim$0.05 pc. We find on average cold gas clumps with temperatures in the range between 10 K and 30 K. The observations do not reveal a clear correlation between infrared emission peaks and ammonia temperature peaks. We report an upper limit for the linewidth of $\sim$1.3 km s$^{-1}$, at the spectral resolution limit of our VLA observation. This indicates a relatively low level of turbulence on the scale of the observations. Velocity gradients are present in almost all regions with typical velocity differences of 1 to 2 km s$^{-1}$ and gradients of 5 to 10 km s$^{-1}$ pc$^{-1}$. These velocity gradients are smooth in most cases, but there is one exceptional source (ISOSS23053), for which we find several velocity components with a steep velocity gradient toward the clump centers that is larger than 30 km s$^{-1}$ pc$^{-1}$. This steep velocity gradient is consistent with recent models of cloud collapse. Furthermore, we report a spatial correlation of ammonia and cold dust, but we also find decreasing ammonia emission close to infrared emission sources.Comment: 20 pages, 10 figure

Observations of new western Mediterranean deep water formation using ARGO floats 2004?2006

International audienceThe deep convection that occurs in the western basin of the Mediterranean Sea was investigated using ARGO float data over two consecutive winters in 2004?2005 and 2005?2006. The results showed deep mixed layers reaching 2000 m in surprising locations, namely the eastern Catalan subbasin (39.785° N, 4.845° E) and the western Ligurian subbasin (43.392° N, 7.765° E). Subsequently, new deep water was formed in March of 2005 and 2006 with ?=12.89?12.92°C, S=38.48?38.49 and ??=29.113 kg m?3. The deep water produced in the Ligurian subbasin during 2006 was more saline, warmer and denser than any historical observations of Western Mediterranean Deep Water. The results show S, ? and ?? in the Western Mediterranean Deep Water are higher than 1990s values, with a salinity increase of 1.5×10?3 yr?1, a temperature increase of 3.6×10?3°C yr?1 and a density increase of 4.0×10?4 kg m?3 yr?1 apparent from a dataset of WMDW properties spanning 1955?2006