The origin of Sr segregation at La1-xSrxMnO3 surfaces

A uniform distribution of La and Sr in lanthanum-strontium manganites would lead to charged crystal planes, a charged surface, and arbitrarily large surface energy for a bulk crystal. This divergent energy can be eliminated by depleting the La concentration near the surface. Assuming an exponential form for segregation suggested by experiment, the total electrostatic energy is calculated, depending only upon the decay length and on an effective charge Z* associated with the La ion. It is found to be lower in energy than neutralization of the surface by changing Mn charge states, previously expected, and lower than simply readjusting the La concentration in the surface plane. The actual decay length obtained by minimizing this electrostatic energy is shorter than that observed. The extension of this mechanism to segregation near the surface in other systems is discussed

Ocean shrimp report 1976 season

Statewide Pacific ocean shrimp, Pandalus jordani, landings totaled 3,400,191 lb, down from the 1975 record catch of 4,992,233 lb but well above the 10-year (1966-1975) mean of 2.6 million lb. Landings from Areas A (Eureka-Crescent City) and B-1 (Fort Bragg) were 2.7 and 0.7 million lb, respectively. Only negligible amounts were landed in Areas B-2 (Bodega Bay) and C (Avila-Morro Bay). In Areas A and B-1 catch per hour trawled by single-rig vessels ranged from 294 to 1,803 lb while catch per hour by double-rig vessels ranged from 431 to 3,428 lb. Two-year-old (1974 year class) shrimp dominated the catches during the first part of the season, but 1-year-old (1975 year class) shrimp dominated the catches from August to October. The outlook for the 1977 season in Areas A, B-1 and B-2 is good because of the strong showing of the 1975 year class. (15pp.

Two-loop electroweak contributions to Δr\Delta r

A review is given on the quantum correction $\Delta r$ in the $W$--$Z$ mass correlation at the electroweak two-loop level, as derived from the calculation of the muon lifetime in the Standard Model. Exact results for $\Delta r$ and the $W$-mass prediction including ${\mathcal{O}}(\alpha^2)$ corrections with fermion loops are presented and compared with previous results of a next-to-leading order expansion in the top-quark mass.Comment: 14 pages, including 4 figures. Presented at the 5th International Symposium on Radiative Corrections, (RADCOR-2000), Carmel CA, USA, 11-15 September 200

Biogenesis of cytochrome c1

The biogenesis of cytochrome c1 involves a number of steps including: synthesis as a precursor with a bipartite signal sequence, transfer across the outer and inner mitochondrial membranes, removal of the first part of the presequence in the matrix, reexport to the outer surface of the inner membrane, covalent addition of heme, and removal of the remainder of the presequence. In this report we have focused on the steps of heme addition, catalyzed by cytochrome c1 heme lyase, and of proteolytic processing during cytochrome c1 import into mitochondria. Following translocation from the matrix side to the intermembrane-space side of the inner membrane, apocytochrome c1 forms a complex with cytochrome c1 heme lyase, and then holocytochrome c1 formation occurs. Holocytochrome c1 formation can also be observed in detergent-solubilized preparations of mitochondria, but only after apocytochrome c1 has first interacted with cytochrome c1 heme lyase to produce this complex. Heme linkage takes place on the intermembrane- space side of the inner mitochondrial membrane and is dependent on NADH plus a cytosolic cofactor that can be replaced by flavin nucleotides. NADH and FMN appear to be necessary for reduction of heme prior to its linkage to apocytochrome c1. The second proteolytic processing of cytochrome c1 does not take place unless the covalent linkage of heme to apocytochrome c1 precedes it. On the other hand, the cytochrome c1 heme lyase reaction itself does not require that processing of the cytochrome c1 precursor to intermediate size cytochrome c1 takes place first. In conclusion, cytochrome c1 heme lyase catalyzes an essential step in the import pathway of cytochrome c1, but it is not involved in the transmembrane movement of the precursor polypeptide. This is in contrast to the case for cytochrome c in which heme addition is coupled to its transport directly across the outer membrane into the intermembrane space

Early steps in mitochondrial protein import

The process of insertion of precursor proteins into mitochondrial membranes was investigated using a hybrid protein (pSc1-c) that contains dual targeting information and, at the same time, membrane insertion activity. pSc1-c is composed of the matrix-targeting domain of the cytochrome c1 presequence joined to the amino terminus of apocytochrome c. It can be selectively imported along either a cytochrome c1 route into the mitochondrial matrix or via the cytochrome c route into the intermembrane space. In contrast to cytochrome c1, pSc1-c does not require the receptor system/GIP for entry into the matrix. The apocytochrome c in the pSc1-c fusion protein appears to exert its membrane insertion activity in such a manner that the matrix-targeting sequence gains direct access to the membrane potential-dependent step. These results attribute an essential function to the receptor system in facilitating the initial insertion of precursors into the mitochondrial membranes

Human Papillomavirus Awareness, Vaccine Status, and Risk Factors in Female Emergency Patients

Introduction: A vaccine targeting high-risk human papillomavirus (HPV) strains can effectively prevent HPV-associated cervical cancer risk. However, many girls and women do not receive the vaccine, more often those impacted by health disparities associated with race and/or socioeconomic status. This same disparate population has also been shown to be at higher risk for cervical cancer. Many of these women also rely on the emergency department (ED) as a safety net for their healthcare. This study sought to gather information pertaining to HPV and cervical cancer risk factors, awareness of HPV and the vaccine, as well as HPV vaccine uptake in female patients presenting to an ED.Methods: We obtained 81 surveys completed by female ED patients. Demographics included age, race, income, insurance status, primary care provider status, and known cervical-cancer risk factors. Subsequent survey questions explored respondents’ knowledge, familiarity, and attitudes regarding HPV, cervical cancer, and the HPV vaccine, including vaccination uptake rates. We analyzed data using descriptive statistics and Fisher’s exact test.Results: Approximately one in seven respondents (14.8%) had never previously heard of HPV and 32.1% were unaware of the existence of a HPV vaccine. Minority patients, including those who were Black and Hispanic patients, low income patients, and uninsured and publicly insured patients were less likely to be aware of HPV and the vaccine and likewise were less likely to be offered and receive the vaccine. More than 60% of all respondents (61.3%) had never previously been offered the vaccine, and only 24.7% of all respondents had completed the vaccine series.Conclusion: Female ED patients may represent an at-risk cohort with relatively low HPV awareness and low HPV vaccine uptake. The ED could represent a novel opportunity to access and engage high-risk HPV populations

Dynamics of capillary spreading along hydrophilic microstripes

We have studied the capillary spreading of a Newtonian liquid along hydrophilic microstripes that are chemically defined on a hydrophobic substrate. The front of the spreading film advances in time according to a power law x=Bt1/2. This exponent of 1/2 is much larger than the value 1/10 observed in the axisymmetric spreading of a wetting droplet. It is identical to the exponent found for wicking in open or closed microchannels. Even though no wicking occurs in our system, the influence of surface curvature induced by the lateral confinement of the liquid stripe also leads to an exponent of 1/2 but with a strongly modified prefactor B. We obtain excellent experimental agreement with the predicted time dependence of the front location and the dependence of the front speed on the stripe width. Additional experiments and simulations reveal the influence of the reservoir volume, liquid material parameters, edge roughness, and nonwetting defects. These results are relevant to liquid dosing applications or microfluidic delivery systems based on free-surface flow