A Single-Mode, Diode-Pumped Lma Laser To Probe The Spin Orientation Of Ensembles Of 3he And 4he

A diode-pumped Nd:Lanthanum Magnesium Hexaluminate laser was constructed which provides up to 15 mW of single-mode, tunable CW emission at 1083 nm. By appropriately polarizing the narrow-band laser emission (< 10 MHz), the laser can be used to determine the populations of the magnetic substates of the He ( 23S1) atoms. The laser is tuned to one of the absorption peaks of the helium metastable atom by tilting a thin (1 mm) solid, coated etalon placed inside the laser cavity and the absorption is measured. The relative absorption is used to determine the ensemble polarization ; the absolute absorption yields the metastable density

A High Power Lna Laser For Application To A New Polarized Electron Source

The recent development of high energy electron accelerators has generated a renewed interest in high current, high polarization electron sources. We have investigated several modifications to a method based on a pumped helium afterglow from which we expect improvements over the performances. These ones include the development of a high power, tunable LNA laser and the application of a new optical pumping scheme to the metastable helium atoms

Our Enemy, the State: Liberty versus Power on the American Home Front during the First World War

World War I marked a significant shift in the structure and practice of the federal government. The key feature of this shift was the centralization of national power in the federal government and a burgeoning bureaucracy. This increase in the centralization of power led to an escalation of conflicts between the expanded assertions of national power and the civil liberties of American citizens. While this relationship between state power and civil liberties has been the focus of extensive scholarly research, much less has been written about a mostly forgotten perspective that viewed war as destructive to human flourishing beyond the dictates of court-defined civil liberties. Based upon a classical liberal tradition, shaped by the experiences of those who lived through the war and adapted by a subsequent generation of libertarian scholars, this study examines the transformation of social power into state power during the First World War through this perspective. American participation in the war redistributed power from the voluntary interactions within society to the coercive hand of the state. The war apparatus on the home front played upon existing prejudices and invented new ones by co-opting social institutions into state-endorsed mechanisms of coercion. Ultimately, the war unleashed a major acceleration in the transformation of social power into state power. This transformation represented a fundamental shift from a society that placed great emphasis on voluntarism to one centered on the use of the force of the state to achieve political aims. In this post-war statism, war became the health of the state, and its long-lasting effects are felt even today

A High-Power Pulsed Xenon Ion Laser As A Pump Source For A Tunable Dye Laser

An inexpensive pulsed xenon ion laser with peak power outputs up to 4 kW has been constructed and used as a pump source for a tunable rhodamine 6G dye laser with a 0.25-A bandpass in the yellow-red range of the spectrum. The dye laser is tunable from 5465 to 6300 A. Over 50 W are obtained at the peak of the tuning range. Copyright © 1975 by The Institute of Electrical and Electronics Engineers, Inc

Optical Pumping In A Flowing Helium Afterglow With Additive Metal Impurity Atoms

It is demonstrated that in a Penning collision of optically oriented metastable helium atoms with an impurity metal atom such as barium, both the longitudinal and transverse components of spin angular momentum are conserved. This results in a polarization of the ion which may be detected by optical emission in the case of excited ion levels or absorption for the ground states. A series of experiments is described which demonstrates the spin dependence of the Penning-collision process. The magnetic resonance of excited-state ions may be observed directly; from the resonance-linewidth radiative lifetimes may be measured. © 1974 The American Physical Society

Energy Transfer Collisions Between Vibrationally Excited Molecular Nitrogen And Atoms

Chemiluminescent reactions between metastable states of molecular nitrogen and atoms are used to determine the vibrational temperatures of these Non radiating molecular systems. The excitation rates of Na, Mg, Cd, and Zn are used to obtain the vibrational temperature of N2(X 1Σ) and N2(A 3Σ) states in a fast-flowing nitrogen afterglow. The exponential dependence of the intensities of the emission from atoms excited by the energy transfer collisions on the energy of the level yields vibrational temperatures on the order of 3100 K. We also report the presence of apparent strong selection rules on the total spin of the system which effectively suppresses energy transfer to the singlet states of magnesium. © 1986 American Institute of Physics

Adenovirus vector expressing Stx1/Stx2-neutralizing agent protects piglets infected with Escherichia coli O157: H7 against fatal systemic intoxication

Hemolytic-uremic syndrome (HUS), caused by Shiga toxin (Stx)-producing Escherichia coli (STEC), remains untreatable. Production of human monoclonal antibodies against Stx, which are highly effective in preventing Stx sequelae in animal models, is languishing due to cost and logistics. We reported previously that the production and evaluation of a camelid heavy-chain-only V(H) domain (VHH)-based neutralizing agent (VNA) targeting Stx1 and Stx2 (VNA-Stx) protected mice from Stx1 and Stx2 intoxication. Here we report that a single intramuscular (i.m.) injection of a nonreplicating adenovirus (Ad) vector carrying a secretory transgene of VNA-Stx (Ad/VNA-Stx) protected mice challenged with Stx2 and protected gnotobiotic piglets infected with STEC from fatal systemic intoxication. One i.m. dose of Ad/VNA-Stx prevented fatal central nervous system (CNS) symptoms in 9 of 10 animals when it was given to piglets 24 h after bacterial challenge and in 5 of 9 animals when it was given 48 h after bacterial challenge, just prior to the onset of CNS symptoms. All 6 placebo animals died or were euthanized with severe CNS symptoms. Ad/VNA-Stx treatment had no impact on diarrhea. In conclusion, Ad/VNA-Stx treatment is effective in protecting piglets from fatal Stx2-mediated CNS complications following STEC challenge. With a low production cost and further development, this could presumably be an effective treatment for patients with HUS and/or individuals at high risk of developing HUS due to exposure to STEC

Tuning Characteristics And New Laser Lines In An Nd:YAP CW Laser

We have investigated the CW laser properties of Nd-doped yttrium-aluminum-perovskite (YAP) in a Kr are-lamp, pumped cavity, Seven laser transitions within the 4F3/2-4I11/2 multiplet have been observed. A simple Lyot filter is used to select the particular transitions. The tuning characteristics of the transitions at 1.0745 and 1.0845 μm were also obtained with the addition of a thin, uncoated etalon within the cavity. Tuning widths of 32 and 23 Å, respectively, were obtained. Copyright © 1986 IEE

A High Power, Tunable, Arc-lamp Pumped Nd-doped Lanthanum-hexaluminate Laser

An LNA (Nd-doped lanthanum-hex aluminate) crystal has been pumped with a cw, krypton arc lamp in a commercial Nd:YAG cavity. The cw output power greater than 6 W is obtained in a 28-cm long, plane mirror cavity. The free-running wavelength is near 1083 nm and has a width of about 0.8 nm. Inserting a 0.25 mm thick, uncoated solid etalon in the cavity permits the laser output to be continuously tuned from 1082 to 1084 nm by tilting the etalon. The laser bandwidth is reduced to below 0.016 nm. Over 3 W are obtained at the helium resonance transition. The maximum power output is limited by severe thermal lensing effects in the LNA crystal. The single, arc-lamp pump is operated at less than 70% of its maximum rated current; thus, substantial increases in the power output can be expected if crystal quality can be improved