Photoluminescence-based detection of particle contamination on extreme ultraviolet reticles.

Here, we propose a comparison-free inspection technique to detect particle contamination on the reticle of extreme ultraviolet (EUV) lithography systems, based on the photoluminescence spectral characteristics of the contaminant particles and their elemental composition. We have analyzed the spectra from different particles found on reticles in EUV lithographic systems and have determined the minimum detectable particle size: 25 nm for organic particles and 100 nm for Al particles. Stainless steel coatings (50 nm thick and 50 × 50 µm(2) in area) exhibit detectable photoluminescence, and the estimated minimum detectable particle is 2 µm.

Drug development in oncology assisted by noninvasive optical imaging.

Early and accurate detection of tumors, like the development of targeted treatments, is a major field of research in oncology. The generation of specific vectors, capable of transporting a drug or a contrast agent to the primary tumor site as well as to the remote (micro-) metastasis would be an asset for early diagnosis and cancer therapy. Our goal was to develop new treatments based on the use of tumor-targeted delivery of large biomolecules (DNA, siRNA, peptides, or nanoparticles), able to induce apoptosis while dodging the specific mechanisms developed by tumor cells to resist this programmed cell death. Nonetheless, the insufficient effectiveness of the vectorization systems is still a crucial issue. In this context, we generated new targeting vectors for drug and biomolecules delivery and developed several optical imaging systems for the follow-up and evaluation of these vectorization systems in live mice. Based on our recent work, we present a brief overview of how noninvasive optical imaging in small animals can accelerate the development of targeted therapeutics in oncology.

Compact cryogenic Kerr microscope for time-resolved studies of electron spin transport in microstructures.

A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configurations. Coupled with a pulsed laser source, the microscope is used to measure the time-resolved Kerr rotation response of semiconductor microstructures with approximately 1 mum spatial resolution. The microscope was designed to study spin transport, a critical issue in the field of spintronics. It is thus possible to generate spin polarization at a given location on a microstructure and probe it at a different location. The operation of the microscope is demonstrated by time-resolved measurements of micrometer distance diffusion of spin polarized electrons in a GaAs/AlGaAs heterojunction quantum well at 4.2 K and 7 T.

Fluorescence diffuse optical tomographic (fDOT) system for small animal studies.

This paper presents a new fluorescence diffuse optical tomographic (fDOT) system and its associated reconstruction method. It is able to reconstruct the fluorescence yield even in heterogeneous and highly attenuating regions. Furthermore our reconstruction method makes mouse inspection without immersion in optical index matching liquid (Intralipid and ink) possible. Some phantom experiments have been carried out to characterize this new fDOT system and to validate its use for heterogeneous media. A mice study consisting in the follow up of the lungs at different stages of tumor development is then related. These results validate the use of our system for biological studies of small animals.

Noncontact fluorescence diffuse optical tomography of heterogeneous media.

Fluorescence-enhanced diffuse optical tomography is expected to be useful to the collection of functional information from small animal models. This technique is currently limited by the extent of tissue heterogeneity and management of the shape of the animals. We propose an approach based on the reconstruction of object heterogeneity, which provides an original solution to the two problems. Three evaluation campaigns are described: the first two were performed on phantoms designed to test the reconstructions in highly heterogeneous media and noncontact geometries; the third was conducted on mice with lung tumors to test fluorescence yield reconstruction feasibility in vivo.

Charge and spin dynamics in a two-dimensional electron gas.

A number of time-resolved optical experiments probing and controlling the spin and charge dynamics of the high-mobility two-dimensional electron gas in a GaAs/AlGaAs heterojunction are discussed. These include time-resolved reflectivity, luminescence, transient grating, magneto-optical Kerr effect, and electro-optical Kerr effect experiments. The optical experiments provide information on the carrier lifetimes and spin dephasing times, as well as on the carrier diffusion coefficient which directly gives the charge mobility. A combination of the two types of Kerr experiment proves to be useful in extracting both the carrier lifetimes and spin dephasing times in a single experiment.

[Survival of patients with HIV-related tuberculosis. Study of mortality during the first 9 months of treatment]. / Supervivencia en pacientes con tuberculosis infectados por VIH. Estudio de los fallecimientos en los primeros nueve meses de tratamiento.

BACKGROUND: Among the individuals with tuberculosis who are infected with HIV a high degree of lethality has been found to exist during the first few weeks following the start of tuberculosis treatment. In this study, the survival of these individuals is studied within the framework of a retrospective cohort study. METHODS: This study included 1135 subjects infected by HIV over age fifteen and residents of Barcelona who were registered by the Barcelona Tuberculosis Prevention and Control Program and were diagnoses within the 1988-1993 period. The variables analyzed were age, gender, former imprisonment, municipal district, risk group, percentage of T CD4+ lymphocytes, tuberculin test, AIDS diagnosis (as per CDC-1987), X-ray pattern, bacteriology and part of the body affected by the tuberculosis. The Cox semiparametric method, the Kaplan-Meir curves and the log-rank test were employed. RESULTS: A 77% probability of survival during the first nine months was found to exist, with wide-ranging variations among the different subgroups. The only significant variables in the Cos multivariate model were AIDS, the percentage of T CD4+ lymphocytes and their interaction. The risk of death for an individual not having AIDS and a T CD4+ lymphocyte percentage of 14% or lower was 7.69 times higher than the risk of dying for an individual not having AIDS who had a T CD4+ lymphocyte percentage of above 14%. CONCLUSIONS: The survival of those individuals having tuberculosis who are infected with HIV varies greatly. Those who died in the short term were diagnosed as having AIDS on starting the tuberculosis treatment and who also had a T CD4+ lymphocyte percentage of 14% or lower.

[Infectious disease and sociodemographic characteristics of foreign immigrants in the Central Penitentiary for Men in Barcelona]. / Enfermedades infecciosas y características sociodemográficas de los inmigrantes extranjeros del Centro penitenciario de Hombres de Barcelona.

BACKGROUND: Immigration from socioeconomically under-developed countries is relatively recent in our country. Analyzing the impact of diseases such as HIV/AIDS and tuberculosis among these populations is of particular interest with regard to public health. METHODS: Case study and tests conducted at the Male Prison Facility in Barcelona from January 1, 1996 to September 30, 1996, the cases being the foreign immigrants from socioeconomically underdeveloped countries, and the checks of the native prisoners paired by age (+/- 5 years). A description is provided of the epidemiological and sociodemographic characteristics of the immigrants, and a comparison is drawn between the two populations. RESULTS: 450 prisoners, 300 native and 150 immigrants. Sixty-three percent (63%) of the immigrants were from the Maghreb, 72% being in this country illegally, 55% having resided in our country for over 5 years and 53% not living with any family members. The immigrants used less injected drugs that the native prisoners (OR: 0.2; IC95% 0.09-0.41), had less HIV infection (OR: 0.2; IC95% 0.05-0.49) and lived to a lesser extent with family (OR: 0.2; IC95% 1.011-0.36). No differences were found to exist with regard to infection by Mycobacterium tuberculosis nor tubercular disease. The legal immigrants were older (OR: 1.07; IC95% 1.01-1.13) lived to a greater extent with family (OR: 2.7; IC95% 1.23-5.80) and drank more alcohol (OR: 1.7; IC95% 1.07-2.59) than the illegal residents. CONCLUSIONS: The native prisoners had HIV to a greater extent than the immigrants, the use of injected drugs, more common among the natives, bearing an influence on this aspect. As regards the immigrants, the high degree of illegal residence and the absence of a stable core family comprise indicators of a situation of being socially disadvantaged.

[Extension of reporting AIDS cases in Catalonia: study based on requests for CD4 lymphocyte count and prescription of antiretroviral drugs]. / Exhaustividad de la notificación de los casos de SIDA en Cataluña: un estudio basado en las solicitudes de determinaciones de linfocitos CD4 y en la prescripción de antirretrovirales.

BACKGROUND: To ascertain the degree to which AIDS is officially reported in Catalunya. METHOD: The request for T CD4+ white blood cell counts and the prescribing of antiretroviral drugs in seven university hospitals in Catalunya from January 1, 1994 to June 31, 1994 were used as data-comparison sources. A case was considered to not have been reported when the clinical history showed a diagnosis of AIDS (according to the Europe 93 definition) and the case in question did not show up on the AIDS Registry for Catalunya. RESULTS: Of the 1,370 cases studied, 50 unreported AIDS cases were found. In all, 98.6% of all cases were found to have been reported, for a 95% confidence interval (95% CI): 98.2-99.0. Most of the unreported cases were males (72%) averaging 37.3 years of age (HCA: 11.8), 52% of whom were injected drug users (IDU's), extrapulmonary tuberculosis being the disease most often diagnosed (16%), 81.4% having been found to have a T CD4+ white blood cell count of 200 WBC/mm3 or below. 92% of these cases were detected based on T CD4+ white blood cell counts. CONCLUSIONS: The degree of completeness found is considered to be adequate. It is recommended that the white blood cell count records being used for this type of studies.

The El Paso smelter 20 years later: residual impact on Mexican children.

Although there has been considerable concern regarding cross-border industrial contamination between Mexico and the United States, there are remarkably few data. One notable case study is the smelter in El Paso, Texas. In 1974 blood lead levels higher than 40 micrograms/dl were detected in 52% of children studied near the smelter, in the adjacent Mexican community of Anapra in Ciudad Juarez, Chihuahua. Lead smelting at this plant was halted in 1985, and as a result, lead levels in air decreased sharply; consequently, children's exposure to lead and other metals should have diminished accordingly. In order to assess the effect of removal of lead emissions from the area, three geographical locations in Anapra, varying in distance from the smelter source, were evaluated for lead, arsenic, and cadmium levels in soil and for lead in blood of children. It was found that lead levels in soil were inversely correlated with distance from the smelter. Arsenic and cadmium levels in soil were constant among the three sectors. However, at residential sites closer to the smelter, a higher percentage of children was found with blood lead levels exceeding the Centers for Disease Control's action level of 10.0 micrograms/dl. In the sector closest to the border 43% of children had blood lead levels greater than 10.0 micrograms/dl. Although blood lead levels in children living in Anapra have dropped approximately fourfold in 20 years, our results indicate a moderate continued risk of lead exposure. This study demonstrates the persistent impact that may result from cross-border contamination and raises provocative questions regarding appropriate action and the responsibility for financing such action.

Three-dimensional magnetic resonance microscopy of materials.

Several aspects of magnetic resonance microscopy are examined employing three-dimensional (3D) back-projection reconstruction techniques in combination with either simple Bloch-decay methods or MREV-8 multiple-pulse line narrowing techniques in the presence of static field gradients. Applications to the areas of ceramic processing, catalyst porosity measurements and the characterization of polymeric materials are presented. The focus of the discussion centers on issues of sensitivity and resolution using this approach compared with other methods. Advantages and limitations of 3D microscopy over more commonly employed slice selection protocols are discussed, as well as potential remedies to some of the inherent limitations of the technique.

Cone-beam SPECT with a tilted detector.

In this article we report on the TOMOCONIC project for cerebral SPECT using cone-beam collimators. First, we describe our experimental set-up. The cone-beam collimator improves both spatial resolution and sensitivity. We tilt the detector to center the focal point rotation plane on the region to reconstruct. Then, to minimize cone-beam artefacts, we use the Grangeat algorithm for image reconstruction. We describe here how it can be generated to this tilted acquisition geometry. Finally, we present our first experimental results and a comparison with parallel-beam SPECT. The improvement ratio on transverse spatial resolution is 1.5. We conclude with our first clinical images.