ABSTRACT
Recent work has indicated the potential of light to modify the growth of neuronal cells. The two reported studies however, were performed on two independent optical set-ups and on differing cell-types at different temperatures and at different wavelengths. Therefore, it is unknown whether there is a bias for this effect to a particular wavelength which would have implications for the mechanisms for this phenomenon. Localized changes in heat have been suggested as a possible mechanism for this process, but as yet there is no direct experimental evidence to support or discount this hypothesis. In this paper, we report the first direct comparison on one cell type, of this process at two near infra-red wavelengths: 780 nm and 1064 nm using exactly the same beam shape. We show that light at both wavelengths is equally effective in initiating this process. We also directly measure the temperature rise caused by each wavelength in water and its absorption in the cellular medium. The recorded temperature rises are insufficient to change the rate of actin polymerization.
ABSTRACT
Many health care issues of greatest concern to consumers-including provider choice, costs and continuity of care-depend on health plans' ability to maintain adequate networks of hospitals, physicians and other caregivers. When providers drop out of plan networks, consumers may suddenly face the choice of changing caregivers or paying more for out-of-network care. Network instability is increasingly common in health care markets across the country and can arise from health plan-provider contract disputes and provider organization insolvencies. This Issue Brief, which is based on the Center for Studying Health System Change's (HSC) 2000-01 site visits to 12 nationally representative communities, examines this growing trend and the implications for consumers, including diminished choice and higher costs.
Subject(s)
Continuity of Patient Care , Delivery of Health Care, Integrated , Patient Participation , Consumer Behavior , Delivery of Health Care, Integrated/organization & administration , Humans , Managed Care Programs , Medicaid , Medicare , Patient Advocacy , United StatesABSTRACT
We demonstrate 250 mW of single-frequency 532-nm output from a simple intracavity-doubled Nd:YVO(4) laser, pumped with 1.2 W from a fiber-coupled diode laser. The laser can be frequency chirped smoothly over approximately 17 GHz while maintaining a single-frequency green output of greater than 200 mW. A short Fabry-Perot cavity is used, and single-frequency operation is enforced by means of a birefringent filter that utilizes the birefringence of both the KTP doubling crystal and the Nd:YVO(4) laser crystal with polarization-dependent loss from a glass Brewster plate combined with polarization-dependent gain from the laser crystal.
