ABSTRACT
Computer simulations and experiments have been performed to quantify the effects of nozzle shape and skimmer placement on high-density supersonic jets. It is shown that the on axis beam intensity achieved is much higher than intensity achieved using standard sonic nozzles. Changes in skimmer design and positioning are required to allow this intense jet to propagate in a typical supersonic beam setup.
ABSTRACT
We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.
ABSTRACT
We report the slowing of a supersonic beam by elastic reflection from a receding atomic mirror. We use a pulsed supersonic nozzle to generate a 511+/-9 m/s beam of helium that we slow by reflection from a Si(111)-H(1x1) crystal placed on the tip of a spinning rotor. We were able to reduce the velocity of helium by 246 m/s and show that the temperature of the slowed beam is lower than 250 mK in the comoving frame.
ABSTRACT
Connected logic gates can be operated on the levels of one molecule by making use of the special properties of high Rydberg states. Explicit experimental results for the NO molecule are provided as an example. A number of other options, including that of several gates concatenated so as to operate as a full adder, are discussed. Specific properties of high Rydberg states that are used are: their autoionization is delayed so that they can be distinguished from direct multiphoton ionization, during their long life such states also can decay by energy transfer to the molecular core in a way that can be controlled by the judicious application of very weak external electrical fields, and the Rydberg states can be detected by the application of an ionizing electrical field. The combination of two (or three) color photons with and without external weak fields allows the construction of quite elaborate logic circuit diagrams and shows that taking advantage of the different intramolecular dynamics of levels that differ by their excitation enables the compounding of logic operations on one molecular frame.
ABSTRACT
Giardia lamblia infection was identified in 33 of 89 (37%) 3-month-old to 3-yr-old children who were followed with monthly stool examinations for up to 12 months in a day care center. The infection was mainly asymptomatic and usually associated with prolonged carriage of the parasite. There were no significant differences for height and weight achievements and mean hemoglobin values between Giardia-positive and Giardia-negative children. However, Giardia-positive children tended to achieve higher weight and height for age than Giardia-negative children; weight for age was above the 50th percentile in 69% of Giardia-positive vs. 40% of Giardia-negative children (alpha = 0.01). Giardia-positive children tended to have fewer symptoms related to the gastrointestinal and respiratory tracts as recorded by a weekly questionnaire. Lactase deficiency was detected by breath hydrogen testing in 8 of 26 Giardia-positive vs. only 1 of 21 Giardia-negative children (P less than 0.02). Healthy day care children with asymptomatic Giardia infection show no disadvantage and perhaps even an advantage in nutritional status and freedom from other illnesses.
Subject(s)
Carrier State/physiopathology , Giardiasis/physiopathology , Body Height , Body Weight , Breath Tests , Carrier State/epidemiology , Child Day Care Centers , Child, Preschool , Diarrhea/epidemiology , Disease Outbreaks , Feces/parasitology , Giardiasis/epidemiology , Hemoglobins/analysis , Humans , Infant , Israel/epidemiology , Prevalence , Prospective Studies , Surveys and Questionnaires , beta-Galactosidase/deficiencyABSTRACT
An electrodeless (double induction) technique has been developed for the determination of Hall mobility. Measurements were performed on seven solid or liquid metallic samples and the results compared to reported mobilities. With a current of 1 A and magnetic field of 100 G, signals of 100 nV were measured for Cu, Ag, or Au samples, while signals as low as 50 pV can be measured. Hall angles as small as 2 x 10(-6) rad have been determined. The usefulness of this technique in Hall mobility measurements on systems in which electrode dependent results occur or in corrosive materials on which no electrode is stable is emphasized.
