Internally sensed optical phased array

Extending phased array techniques to optical frequencies is challenging because of the considerably smaller wavelengths and the difficulty of stabilizing the optical path lengths of multiple emitters to this level of precision. This is especially true under real-world conditions where thermal and vibrational disturbances cause path length variations that are considerable in relation to the wavelength. Earlier attempts have relied on an external mechanism to sense and compensate for any unwanted variations in the outgoing beams. Here we propose and demonstrate a method that does not rely on any external components. The method combines a pseudo-random noise phase modulation scheme together with conventional heterodyne interferometry to simultaneously measure phase variations between emitters. This information is then used to control the relative phases between the emitters and compensate for any unwanted disturbance. Experimental results are presented that support the viability of this design.

Lessons from the 2006 Louisiana health and population survey

The 2005 hurricane season caused extensive damage and induced a mass migration of approximately 1.1 million people from southern Louisiana in the United States. Current and accurate estimates of population size and demographics and an assessment of the critical needs for public services were required to guide recovery efforts. Since forecasts using pre-hurricane data may produce inaccurate estimates of the post-hurricane population, a household survey in 18 hurricane-affected parishes was conducted to provide timely and credible information on the size of these populations, their demographics and their condition. This paper describes the methods used, the challenges encountered, and the key factors for successful implementation. This post-disaster survey was unique because it identified the needs of the people in the affected parishes and quantified the number of people with these needs. Consequently, this survey established new population and health indicator baselines that otherwise would have not been available to guide the relief and recovery efforts in southern Louisiana.

Interleukin-15 and the growth of tumor derived activated T-cells

Interleukin-15 was tested to determine whether this recently discovered cytokine was capable of stimulating the growth of tumor derived activated T cells in culture (TDAC, also referred to as tumor infiltrating lymphocytes). When established cultures of IL-2 induced, IL-2 dependent TDAC were tested, IL-15 stimulated growth in a dose dependent manner, alone or in the presence of IL-2. One established TDAC was cultured with IL-15 alone for 18 passages over a 10 week period. Comparing IL-2 and IL-15 treated cultures, growth rate with IL-15 was slower. IL-15 doubled the secreted interferon alpha and granulocyte-macrophage colony stimulating factor. IL-15 and IL-2 were compared in primary TDAC cultures. IL-15 induced TDAC outgrowth in 3 of 6 cultures. IL-2 induced outgrowth in all 6. Tumor cells were eliminated as TDAC grew out in both IL-2 and IL-15 treated cultures. These results suggested that IL-15 like IL-2, is capable of stimulating the growth of TDAC with antitumor activity, but with certain distinct effects which may be of interest therapeutically.

Circadian rhythm of cholesterol-7alpha-hydroxylase and cortisol in the African green monkey (Cercopithecus aethiops)

Cholesterol-7alpha-hydroxylase in African green monkey liver had an apparent Km of 1.65-10(-4) M cholesterol and a pH optimum of 7.4. The amplitudes of the circadian maxima of enzyme activity and serum cortisol levels were significantly greater in vervets than in grivets. Fluctuations in enzyme activity and cortisol levels during the circadian cycle were positively correlated (r = 0.89). Enzyme activities and hormone levels were 2.7-fold lower over a 24-h period in the grivet than in the vervet. Cholesterol feeding reduced the enzyme activity by 40% and serum cortisol was reduced to 38% of control levels at the diurnal peak. Serum glucocorticoids may be important physiological regulators of cholesterol-7alpha-hydroxylase in non-human primates. The concentration of cortisol and its time of release appear to be factors in the hyperresponsive trait of grivets. Genetic differences between vervet and grivet races may account for differences in the amplitude and timing of the circadian rhythm of cholesterol-7alpha-hydroxylase activity possibly influenced by cortisol.