High intensity third harmonic generation using a single crystal of BBO

High intensity femtosecond pulses from a CPA laser are used to generate .6 mJ of light at 351 nm (6% efficiency) in a single crystal of BBO. The values of {xi}{sub ij}{sup (3)} are measured for BBO

Petawatt laser system and targeting performance

We recently demonstrated the production of 1.25 PW of peak power in the Nova/Petawatt Laser Facility, generating > 600 J in < 450 fs. Results of the first focused irradiance tests, at 500 J and deployment of a novel targeting system will be presented

President\u27s Council of Black Education Correspondence 1970

Correspondence between President of USF, Albert R. Jonsen, Herold L. Perry, Samuel L. Kountz, Terry A. Francois, and Burl A. Toler regarding the creation of the President\u27s Council of Black Education

Ultrahigh spatial-frequency, high-contrast periodic structures produced by interference lithography

We have developed a process to produce high-aspect ratio, high- frequency periodic profiles recorded in a photoresist layer by interference lithography. We are able to independently control the period, duty cycle, and sidewall angle of the profiles. High-contrast diazonapthoquinone-based photoresist and single mode operation of the exposure laser are critical. The high-aspect ratio profiles are necessary for many applications such as transfer etch masks for etching oxides and field emitter array patterning. 5 refs., 5 figs

Harmonics generation in electron-ion collisions in a short laser pulse

Anomalously high generation efficiency of coherent higher field-harmonics in collisions between {\em oppositely charged particles} in the field of femtosecond lasers is predicted. This is based on rigorous numerical solutions of a quantum kinetic equation for dense laser plasmas which overcomes limitations of previous investigations.Comment: 4 pages, 4 eps-figures include

Morphometric analyses and gene expression related to germ cells, gonadal ridge epithelial-like cells and granulosa cells during development of the bovine fetal ovary

Cells on the surface of the mesonephros give rise to replicating Gonadal Ridge Epithelial-Like (GREL) cells, the first somatic cells of the gonadal ridge. Later germ cells associate with the GREL cells in the ovigerous cords, and the GREL cells subsequently give rise to the granulosa cells in follicles. To examine these events further, 27 bovine fetal ovaries of different gestational ages were collected and prepared for immunohistochemical localisation of collagen type I and Ki67 to identify regions of the ovary and cell proliferation, respectively. The non-stromal cortical areas (collagen-negative) containing GREL cells and germ cells and later in development, the follicles with oocytes and granulosa cells, were analysed morphometrically. Another set of ovaries (n = 17) were collected and the expression of genes associated with germ cell lineages and GREL/granulosa cells were quantitated by RT-PCR. The total volume of non-stromal areas in the cortex increased significantly and progressively with ovarian development, plateauing at the time the surface epithelium developed. However, the proportion of non-stromal areas in the cortex declined significantly and progressively throughout gestation, largely due to a cessation in growth of the non-stroma cells and the continued growth of stroma. The proliferation index in the non-stromal area was very high initially and then declined substantially at the time follicles formed. Thereafter, it remained low. The numerical density of the non-stromal cells was relatively constant throughout ovarian development. The expression levels of a number of genes across gestation either increased (AMH, FSHR, ESR1, INHBA), declined (CYP19A1, ESR2, ALDH1A1, DSG2, OCT4, LGR5) or showed no particular pattern (CCND2, CTNNB1, DAZL, FOXL2, GATA4, IGFBP3, KRT19, NR5A1, RARRES1, VASA, WNT2B). Many of the genes whose expression changed across gestation, were positively or negatively correlated with each other. The relationships between these genes may reflect their roles in the important events such as the transition of ovigerous cords to follicles, oogonia to oocytes or GREL cells to granulosa cells.Katja Hummitzsch, Nicholas Hatzirodos, Helen F. Irving-Rodgers, Monica D. Hartanti, Viv E. A. Perry, Richard A. Anderson, Raymond J. Rodger

The Carriage of Multiresistant Bacteria after Travel (COMBAT) prospective cohort study: Methodology and design

Background: Antimicrobial resistance (AMR) is one of the major threats to public health around the world. Besides the intense use and misuse of antimicrobial agents as the major force behind the increase in antimicrobial resistance, the e

Enhancement of bichromatic high-harmonic generation with a high-frequency field

Using a high-frequency field superposed to a linearly polarized bichromatic laser field composed by a wave with frequency $\omega$ and a wave with frequency $2\omega$, we show it is possible to enhance the intensity of a group of high harmonics in orders of magnitude. These harmonics have frequencies about 30% higher than the monochromatic-cutoff frequency, and, within the three-step-model framework, correspond to a set of electron trajectories for which tunneling ionization is strongly suppressed. Particular features in the observed enhancement suggest that the high-frequency field provides an additional mechanism for the electron to reach the continuum. This interpretation is supported by a time-frequency analysis of the harmonic yield. The additional high frequency field permits the control of this group of harmonics leaving all other sets of harmonics practically unchanged, which is an advantage over schemes involving only bichromatic fields.Comment: 6 pages RevTex, 5 figures (ps files), Changes in text, figures, references and equations include

Comparison of soft and hard tissue ablation with sub-ps and ns pulse lasers

Tissue ablation with ultrashort laser pulses offers several unique advantages. The nonlinear energy deposition is insensitive to tissue type, allowing this tool to be used for soft and hard tissue ablation. The localized energy deposition lead to precise ablation depth and minimal collateral damage. This paper reports on efforts to study and demonstrate tissue ablation using an ultrashort pulse laser. Ablation efficiency and extent of collateral damage for 0.3 ps and 1000 ps duration laser pulses are compared. Temperature measurements of the rear surface of a tooth section is also presented

Relationship between foot pronation and rotation of the tibia and femur during walking

ABSTRACT The purpose of this study was to test the hypothesis that the magnitude and timing of peak foot pronation would be predictive of the magnitude and timing of peak rotation of tibia and femur. Thirty subjects who demonstrated a wide range of pronation participated. Threedimensional kinematics of the foot, tibia, and femur segments were recorded during self-selected free walking trials using a six-camera VICON motion analysis system. Regression analysis demonstrated that the magnitude and timing of peak pronation was not predictive of the magnitude and timing of tibial and femoral rotation. The lack of a relationship between peak foot pronation and the rotation of the tibia and femur is contrary to the clinical hypothesis that increased pronation results in greater lower extremity rotation. It would seem, therefore, that the relationship between foot pronation and rotation of the lower extremity segments should be assessed on a patient-by-patient basis