Dark Matter Search Results from the PICO-60 C_{3}F_{8} Bubble Chamber.

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C_{3}F_{8} located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C_{3}F_{8} exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41} cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.

Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber.

New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5×10(-10) and an alpha rejection factor of >98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

Improved limits on spin-dependent WIMP-proton interactions from a two liter CF3I bubble chamber.

Data from the operation of a bubble chamber filled with 3.5 kg of CF3I in a shallow underground site are reported. An analysis of ultrasound signals accompanying bubble nucleations confirms that alpha decays generate a significantly louder acoustic emission than single nuclear recoils, leading to an efficient background discrimination. Three dark matter candidate events were observed during an effective exposure of 28.1 kg day, consistent with a neutron background. This observation provides strong direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering for WIMP masses >20 GeV/c2.

Spin-dependent WIMP limits from a bubble chamber.

Bubble chambers were the dominant technology used for particle detection in accelerator experiments for several decades, eventually falling into disuse with the advent of other techniques. We report here on a new application for these devices. We operated an ultraclean, room-temperature bubble chamber containing 1.5 kilograms of superheated CF3I, a target maximally sensitive to spin-dependent and -independent weakly interacting massive particle (WIMP) couplings. An extreme intrinsic insensitivity to the backgrounds that commonly limit direct searches for dark matter was measured in this device under operating conditions leading to the detection of low-energy nuclear recoils like those expected from WIMPs. Improved limits on the spin-dependent WIMP-proton scattering cross section were extracted during our experiments, excluding this type of coupling as a possible explanation for a recent claim of particle dark-matter detection.

Simulation of special bubble detectors for PICASSO.

The PICASSO project is a cold dark matter (CDM) search experiment relying on the superheated droplet technique. The detectors use superheated freon liquid droplets (active material) dispersed and trapped in a polymerised gel. This detection technique is based on the phase transition of superheated droplets at about room temperature and ambient pressure. The phase transition is induced by nuclear recoils when an atomic nucleus in the droplets interacts with incoming subatomic particles. This includes CDM particles candidate as the neutralino (a yet-to-discover particle predicted in extensions of the standard model of particle physics). Simulations performed to understand the detector response to neutrons and alpha particles are presented along with corresponding data obtained at the Montreal Laboratory.

Direct dark matter search using large-mass superheated droplet detectors in the PICASSO experiment.

The PICASSO experiment investigates the presence and nature of dark matter in the Universe. The experiment is based on the detection of acoustic signals generated in explosive phase transitions induced by dark matter particles. This technique is an alternative more traditional detection technique like scintillation and ionisation, which are largely employed for dark matter search. One of the main advantages of this technique, besides its sensitivity to very low nuclear recoil energies (few keV), is its excellent background suppression features. A pilot experiment consisting of six superheated droplet detectors (40 g of active mass) is presently taking data at the Sudbury Neutrino Observatory (SNO) at a depth of 2000 m. We discuss the operation, calibration and data acquisition of the experiment and also the ongoing work to increase the sensitivity and the active mass of the detectors.

Biodosimety Assessment Tool: a post-exposure software application for management of radiation accidents.

The Biodosimetry Assessment Tool software application under development will equip health care providers with diagnostic information (clinical signs and symptoms, physical dosimetry, etc.) germane to the management of human radiation casualties. Designed primarily for prompt use after a radiation incident, the user-friendly program facilitates collection, integration, and archiving of data obtained from exposed persons. Data collected in templates are compared with established radiation dose responses obtained from the literature to provide multiparameter dose assessments. The program archives clinical information (e.g., extent of contamination, wounds, infection, etc.) useful for casualty management, displays relevant diagnostic information in a concise format, and can be used to manage both military and civilian radiation accidents. In addition, monitoring of diagnostic information of individuals using this program could potentially minimize the severity of psychological casualties by making a marked impact on the way that both radiation casualties and the worried well view their exposure, dose, and future risk for the development of disease.

Using qualitative data to inform public policy: evaluating "choose to de-fuse".

There are many preventive programs and interventions designed to address the complex problems of youth violence. However, research that examines the effectiveness of such programs is scarce. This article describes the evaluation of a media communications strategy, Choose to De-Fuse, developed for at-risk inner-city youth, and provides a case study of how qualitative data can be used to inform public policy.

Antifungal cyclic peptides from the terrestrial blue-green alga Anabaena laxa. I. Isolation and biological properties.

Laxaphycins are responsible for the antifungal and cytotoxic activity of crude ethanolic extracts from the cultured blue-green alga Anabaena laxa. These cyclic peptides exhibit an unusual biological synergism when tested for antifungal or cytotoxic effects. The isolation procedure for the peptides, their characterization and biological activities are described here along with experiments demonstrating synergism between the two major laxaphycins.

Westiellamide, a bistratamide-related cyclic peptide from the blue-green alga Westiellopsis prolifica.

The isolation and structural elucidation of westiellamide [1] from the terrestrial blue-green alga Westiellopsis prolifica is described. This moderately cytotoxic cyclic peptide appears to be identical with a bistratamide-type marine natural product from the aplouso-branch ascidian Lissoclinum bistratum.

A decade of research and services for homeless mentally ill persons. Where do we stand?

Over the past decade, researchers have documented the range of needs and devised new methods for increasing our understanding of the homeless severely mentally ill population. Clinicians have developed an appreciation of the difficulty and complexity of effectively treating this population, and policymakers have become increasingly aware of the barriers to developing services and housing. In this article, the progress-to-date in research, the evolution of new service approaches, and the development of federal, state, and local policies to meet the needs of homeless mentally ill individuals are assessed. The many challenges that remain are also considered.

The Ural train-gas pipeline catastrophe: the report of the IDF medical corps assistance.

Following the destruction of two trains in the Urals 2000 km east of Moscow, as a consequence of the conflagration caused by an explosion from a leaking natural gas pipeline, 3000 people were injured;* most of them (2200) died* immediately and the others (about 800) were badly burned. At the request of the Soviet Union Government a medical military delegation was sent to give assistance to the injured people. This report describes the treatment given by the delegation to 40 patients with burns of between 40 and 90 per cent TBSA during a period of 10 days. An insight into a Soviet Union Trauma Center is given and the good treatment given by the Soviet colleagues is emphasized.

Cytotoxic, antiviral indolocarbazoles from a blue-green alga belonging to the Nostocaceae.

6-Cyano-5-methoxy-12-methylindolo[2,3-alpha]carbazole and 6-cyano-5-methoxyindolo[2,3-alpha]carbazole are responsible for most of the cytotoxicity and antiviral activity associated with the blue-green alga Nostoc sphaericum EX-5-1. The compounds are active against HSV II and show weak cytotoxicity against KB and LoVo human carcinoma cell lines.

Mental health services for homeless mentally ill persons. Federal initiatives and current service trends.

Recent research suggests that approximately one third of the population of homeless single adults suffer from severe mental illnesses. Despite multiple health, mental health, and social welfare needs, this population is often unable to obtain necessary housing and community-based services. For this reason, since 1982, the National Institute of Mental Health (NIMH) has undertaken a number of federal initiatives to encourage research and assist states and localities in improving services focused on this vulnerable subgroup of the homeless population. This article describes the target population, NIMH research findings, and current mental health service trends--with particular emphasis on two mental health programs established under the Stewart B. McKinney Homeless Assistance Act. Proposed future directions for federal research and evaluation efforts in this area are also discussed.

The expression of HLA class I antigens in germ cell testicular cancer.

The expression of HLA class I antigens in testicular germ cell tumors (TGCTs) was studied by the immunoperoxidase technique. In the normal testicle, the interstitial cells of Leydig as well as most of the germ cells were significantly stained. In typical seminoma, 75% of the tumor cells in stage I and 30% in stage II were stained. In embryonal cell carcinoma, 25% of the cases in stage I and less than 10% of those in stage II were stained. Mature teratoma was stained in most of the cases, whereas in malignant teratoma only 35% of the cases showed some staining of the tumor cells. In mixed tumors each component displayed its characteristic staining pattern. The expression of class I antigens on tumor cells is required for immune recognition and lysis of the tumor by cytotoxic T-cells. The reduced expression of class I antigens that was related to histologic characteristics and stage suggests that some testicular tumors may escape immune surveillance and become biologically more aggressive.

Enhancing mental health services for homeless persons: state proposals under the MHSH Block Grant Program.

The Mental Health Services for the Homeless Block Grant Program has made available more than $57 million to the States in fiscal years 1987-89 to encourage States to develop and strengthen community services for homeless mentally ill persons. Funds were provided for five basic services, which include outreach, case management, mental health treatment, residential support services, and training for service providers. State applications for funds reflected considerable diversity among the services proposed. The manner in which States proposed to use the funds is described, including methods used to identify high need areas and distribute funds and plans for delivering services.