3,901 research outputs found
A Xenon Ion Pumped Blue Dye Laser
A pulsed xenon ion laser with an output power of 5 kW at 364.5 nm has been used as a pump source for several blue dyes. Broadband conversion efficiencies exceed 20 percent. The use of a birefringent filter provides tunable output in the blue region of the spectrum with a bandwidth of 0.08 nm and a pulse width of 120 ns. © 1978 IEE
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Negotiating executive pay. How can psychological theories complement classical and behavioural economics?
Agency theory is the dominant economic model in executive pay research, assuming profit-making organisations and rent-seeking agents, whilst dismissing non-pecuniary motivations, behaviour and agent preference entirely. The assumption of rationality continues to underpin the design of executive compensation, despite ongoing criticism that the validity of agency theory is not represented in the empirical research. This literature review considers both economic and behavioural research in the context of executive pay. Furthermore, it argues in favour of challenging the status quo in a manner which is both different and complementary to the current rational choice models, and which recognises certain pay-related judgements are psychological in nature where individuals are constantly driven to evaluate their own options and abilities
Phosphorus limitation of aboveground production in northern hardwood forests
Forest productivity on glacially derived soils with weatherable phosphorus (P) is expected to be limited by nitrogen (N), according to theories of long-term ecosystem development. However, recent studies and model simulations based on resource optimization theory indicate that productivity can be co-limited by N and P. We conducted a full factorial N × P fertilization experiment in 13 northern hardwood forest stands of three age classes in central New Hampshire, USA, to test the hypothesis that forest productivity is co-limited by N and P. We also asked whether the response of productivity to N and P addition differs among species and whether differential species responses contribute to community-level co-limitation. Plots in each stand were fertilized with 30 kg N·ha−1·yr−1, 10 kg P·ha−1·yr−1, N + P, or neither nutrient (control) for four growing seasons. The productivity response to treatments was assessed using per-tree annual relative basal area increment (RBAI) as an index of growth. RBAI responded significantly to P (P = 0.02) but not to N (P = 0.73). However, evidence for P limitation was not uniform among stands. RBAI responded to P fertilization in mid-age (P = 0.02) and mature (P = 0.07) stands, each taken as a group, but was greatest in N-fertilized plots of two stands in these age classes, and there was no significant effect of P in the young stands. Both white birch (Betula papyrifera Marsh.) and beech (Fagus grandifolia Ehrh.) responded significantly to P; no species responded significantly to N. We did not find evidence for N and P co-limitation of tree growth. The response to N + P did not differ from that to P alone, and there was no significant N × P interaction (P = 0.68). Our P limitation results support neither the N limitation prediction of ecosystem theory nor the N and P co-limitation prediction of resource optimization theory, but could be a consequence of long-term anthropogenic N deposition in these forests. Inconsistencies in response to P suggest that successional status and variation in site conditions influence patterns of nutrient limitation and recycling across the northern hardwood forest landscape
The Hanle Effect In Penning-excited Ions
A thermal beam of helium (23S1) metastable atoms was used to excite coherently the 2P3/2 levels of Ca, Sr and Ba in a Penning ionizing collision. The coherent excitation of the ions appears as a linear polarization of the optical emission from the excited ions. The degree of linear polarization is 5.5, 3.5 and 0.5% for Ca, Sr and Ba, respectively, with the polarization parallel to the beam direction. Hanle effect signals from the 2P3/2 level of Sr were observed and the radioactive decay rate measured
High Flux Beam Source Of Thermal Rare-gas Metastable Atoms
A high-flux beam source has been constructed for the production of helium, neon and argon metastable atoms. The source is a DC electric discharge maintained in an expanding gas. A metastable flux of 3.5*1014, and 7.2*1013 atoms s-1 sr-1 has been achieved with most probable energies of 66, 72 and 74 meV for the helium, neon and argon sources, respectively. Time-of-flight measurements showed the widths of the respective velocity distributions to be 45%, 27% and 27%
Alignment Of Ions In Penning Collisions
The authors have observed the alignment of the 5p P322 state of strontium ions produced in Penning collisions between an unpolarized beam of helium metastable atoms and a strontium vapor target. The alignment is shown by a linear polarization of the optical emission from the excited ion. For a 66-meV beam of helium metastable atoms a 3.5% linear polarization of the emission relative to the beam axis was measured. It is shown how the alignment may be used to determine the probabilities for populating the various final Quasi molecular states of the ion-atom pair. The alignment of the Penning ions is an important new parameter in the description of these reactions. © 1979 The American Physical Society
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