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Biomedical subjects

E Herz

Publications and source records attributed to E Herz.

12 recordsLinked to original sources
PubMed2005

Exciton fine structure in single CdSe nanorods.

We study the optical properties of excitons in one-dimensional (1D) nanostructures at low temperatures. In single CdSe/ZnS core-shell nanorods we observe a fine structure splitting and explain it by exchange interaction. Two peaks are observed with different degrees of linear polarization of DLP<0.85 and DLP>0.95. For small nanorod radii R< or =a(B)/2, an increase in the photoluminescence decay time is found when the temperature increases from 10 to 80 K. The observations are explained by a radius-dependent change in the symmetry of the 1D-exciton ground state which transforms from a dark state into bright states below a critical radius of R(crit) approximately 3.7 nm.

Journal Article↗
PubMed2005

Hybrid epitaxial-colloidal semiconductor nanostructures.

We present a growth technique which combines wet-chemical growth and molecular beam epitaxy (MBE) to create complex semiconductor nanostructures with nanocrystals as active optical material. The obtained results show that wet-chemically prepared semiconductor nanocrystals can be incorporated in an epitaxally grown crystalline cap layer. As an exemplary system we chose CdSe nanorods and CdSe(ZnS) core-shell nanocrystals in ZnSe and discuss the two limits of thin (d approximately 2R) and thick (d>2R) ZnSe cap layers of thickness d for CdSe nanorods and nanodots of radii R between 2 and 4 nm. In contrast to the strain-induced CdSe/ZnSe Stranski-Krastanow growth of a quantum dot layer in a semiconductor heterostructure, the technique proposed here does not rely on strain and thus results in additional degrees of freedom for choosing composition, concentration, shape, and size of the nanocrystals. Transmission electron microscopy and X-ray diffractometry show that the ZnSe cap layer is of high crystalline quality and provides all parameters for a consecutive growth of Bragg structures, waveguides, or diode structures for electrical injection.

Cadmium Compounds↗
PubMed2004

[HIV seroprevalence in ophthalmologic patients of Cameroon].

BACKGROUND: It is difficult to estimate the exact HIV infection rates in countries such as Cameroon because of diagnostic and statistical problems. The majority of people seek help from traditional healers outside the health system. PATIENTS AND METHODS: A screening for human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) was performed on 2452 patients of the western province of Cameroon. All data were evaluated regarding HIV seroprevalence and ophthalmological findings in HIV-seropositive patients. The test covered all patients who came for cataract surgery (group 1), all outpatients with suspicious ophthalmological findings (group 2), and all remarkable patients of the collaborating department of general medicine (group 3) between 20 September 2000 and 20 September 2001. RESULTS: Of the 2452 screened patients, 467 (19.0%) were HIV seropositive. A positive test result was obtained in 29 (5.5%) of the 525 patients in group 1, 154 (35.6%) of the 433 patients in group 2, and 284 (19.0%) of the 1494 patients in group 3. The main ocular manifestations of the 154 HIV-seropositive patients in group 2 were uveitis (17.6%), squamous cell carcinoma of the conjunctiva (14.9%), zoster ophthalmicus (14.9%), and corneal ulcers (11.0%). CONCLUSIONS: This study shows that the seroprevalence of the screened population of Cameroon lies between 5.5% (results of group 1) and 19.0% (results of group 3).

AIDS-Related Opportunistic Infections↗
PubMed1991

Access to hospital care for California and Michigan Medicaid recipients.

This article is a comparison of the characteristics of hospitals serving the general population and Medicaid recipients in California and Michigan, using data from Medicaid uniform claims files and the American Hospital Association Annual Survey for 1984. A greater concentration of discharges in a small number of "high Medicaid volume" urban and rural hospitals in each State was observed for Medicaid recipients compared with the general population. In addition, discharge data suggest that Supplemental Security Income crossovers (individuals covered by both Medicaid and Medicare) and other recipients (mostly children not enrolled in the Aid to Families with Dependent Children program) receive inpatient care in different hospitals from the general population as well as from other Medicaid eligibility groups. Medicaid cost-containment policies and differential access to hospital care are discussed.

California↗
PubMed1990

Spectrin modifications in a heterozygous case of both hereditary elliptocytosis and beta-thalassemia.

The clinical and hematological parameters of a patient described here, who inherited the genes of both hereditary elliptocytosis (HE) and beta-thalassemia, seem to reflect a mutual enhancement of the two diseases. The coexistence of the two pathologies is probably also responsible for the observed changes in spectrin: the appearance of an extra spectrin band between tetramers and dimers on denaturing gel electrophoresis and the metabolic-dependent reduction in spectrin amount. It is assumed that the instability of the skeletal network that results from the HE pathology caused increased exposure of the spectrin molecule to oxidative damage that usually occurs in thalassemic red cells. The products of such oxidation may have led to abnormal spectrin associations which finally resulted in the above changes.

Chemical Phenomena↗
PubMed1988

A survey of referral activities of agencies serving adolescents.

The referral activities of 373 agencies (38.4% of the sample originally polled) are presented with regard to health care, educational, and social services for teenagers residing in a midwestern metropolitan area. Approximately 66% of the responding agencies receive referrals from without and 87% make referrals to other organizations, with counseling and psychiatry, family planning, and general medical care being the most commonly sought services. Social service agencies had the highest volume of referrals and hospitals the lowest. The results of the survey are discussed in terms of the official recommendations made for coordinated services for teenagers, predicted cutbacks in preventive services, and the special needs of adolescents.

Adolescent↗
PubMed1987

Family planning for inner-city adolescent males: pilot study.

The results of a pilot family planning program (FPP) in a pediatric practice are reported for 66 inner-city male adolescents. The FPP was designed to eliminate registration barriers to the procurement of contraceptives by adolescent males, and to prompt the community neighborhood health center (CNHC) providers to initiate discussion of birth control with their male adolescent patients. Utilization data show that males were more likely to receive contraceptives if the provider first raised the topic of birth control to them. Unstructured follow-up interviews with 27 adolescent male FPP users identified a desire for anonymity/confidentiality and embarrassment or discomfort as the key reasons for not seeking contraceptives from the CNHC. If health care providers are sensitive to male adolescents' feelings about birth control, community health centers potentially could serve as a cost-effective source of contraceptives for sexually active male adolescents.

Adolescent↗
PubMed1986

A baseline evaluation of family support programs.

This paper presents a baseline evaluation of four demonstration family support programs located in communities identified as having a disproportionate number of families at risk for malfunctioning. In this baseline evaluation, a one year cohort of 422 family support participants were assessed along key dimensions of parenting known to contribute to child well-being and potentially to the incidence of child abuse or child neglect. These dimensions include parents' attitudes toward child rearing, knowledge of child development, level of perceived social support, and level of depression. Black participants and teenage parents had more punitive attitudes toward child rearing, less knowledge of child development, and less perceived social support than white or older parents. Overall, attitudes, knowledge, level of perceived social support and depression are interrelated in accordance with previous clinical observations and developmental theory, e.g., depressed parents are less knowledgeable, more punitive and have less support than nondepressed parents. The results of the baseline evaluation suggest that the demonstration projects are successful in reaching some subgroups of families at risk for parenting problems.

Adolescent↗