Label-free highly multimodal nonlinear endoscope.

We demonstrate a 2 mm diameter highly multimodal nonlinear micro-endoscope allowing label-free imaging of biological tissues. The endoscope performs multiphoton fluorescence (3-photon, 2-photon), harmonic generation (second-SHG and third-THG) and coherent anti-Stokes Raman scattering (CARS) imaging over a field of view of 200 µm. The micro-endoscope is based on a double-clad antiresonant hollow core fiber featuring a high transmission window (850 nm to 1800 nm) that is functionalized with a short piece of graded-index (GRIN) fiber. When combined with a GRIN micro-objective, the micro-endoscope achieves a 1.1 µm point spread function (PSF). We demonstrate 3-photon, 2-photon, THG, SHG, and CARS high resolution images of unlabelled biological tissues.

Spatially dispersive amplification in a 12-core fiber and femtosecond pulse synthesis by coherent spectral combining.

A compact scheme is demonstrated for amplification and synthesis of ultrashort pulses by fiber amplifiers. Femtosecond pulses are split in 12 different spectral bands which are amplified separately in the 12 cores of a multicore ytterbium doped fiber. Combining the amplifier outputs together with the intensity and phase management of the spectral bands lead to short pulse synthesis with adjustable pulse shape. The scheme gave an x 92 enhancement in amplified power before the onset of nonlinear effects by comparison with standard stretcher free amplification in a single core fiber.

Simultaneous scalar and cross-phase modulation instabilities in highly birefringent photonic crystal fiber.

We report the experimental observation of scalar and cross-phase modulation instabilities by pumping a highly birefringent photonic crystal fiber in the normal dispersion regime at 45° to its principal polarization axes. Five sideband pairs (two scalar and three vector ones) are observed simultaneously in the spontaneous regime, four of which have a large frequency shift from the pump, in the range 79-93 THz. These results are in excellent agreement with phase-matching arguments and numerical simulations.

Introduction of wavelet analyses to rainfall/runoffs relationship for a karstic basin: the case of Licq-Atherey karstic system (France).

Karstic systems are highly heterogeneous geological formations characterized by a multiscale temporal and spatial hydrologic behavior with more or less localized temporal and spatial structures. Classical correlation and spectral analyses cannot take into account these properties. Therefore, it is proposed to introduce a new kind of transformation: the wavelet transform. Here we focus particularly on the use of wavelets to study temporal behavior of local precipitation and watershed runoffs from a part of the karstic system. In the first part of the paper, a brief mathematical overview of the continuous Morlet wavelet transform and of the multiresolution analysis is presented. An analogy with spectral analyses allows the introduction of concepts such as wavelet spectrum and cross-spectrum. In the second part, classical methods (spectral and correlation analyses) and wavelet transforms are applied and compared for daily rainfall rates and runoffs measured on a French karstic watershed (Pyrénées) over a period of 30 years. Different characteristic time scales of the rainfall and runoff processes are determined. These time scales are typically on the order of a few days for floods, but they also include significant half-year and one-year components and multi-annual components. The multiresolution cross-analysis also provides a new interpretation of the impulse response of the system. To conclude, wavelet transforms provide a valuable amount of information, which may be now taken into account in both temporal and spatially distributed karst modeling of precipitation and runoff.

An assessment of a premedical program in terms of its ability to serve black Americans.

If special programs to increase the number of blacks gaining entry into health professional schools can identify whom they best serve, changes in either the selection process or the curriculum can increase their effectiveness. As one part of an evaluation of the effectiveness of the various components of the prehealth professions program at Xavier University of Louisiana (XU), black freshmen entering the university from 1981 to 1983 in the university's premedical program were tracked to determine who gained entry into medical and related mainline health professional schools upon graduation.The analyses indicate that high-ability black freshmen entering Xavier are more than twice as likely to gain admission into medical school than are their black counterparts nationally, and that this difference is statistically significant beyond the 99 percent level. Fifty-seven percent of high-ability black freshmen (those with American College Testing [ACT] composite scores of 24 or above, the top 2 percent of blacks nationally) who entered XU's biology or chemistry programs during the period under study gained entry into medical school upon graduation, whereas a study by the Educational Testing Service indicates that only 24 percent of similar blacks nationally gain entry into any graduate or professional school.The present study suggests that XU's premedical program serves those blacks who are not in the high-ability group (those whose ACT scores are below 24) at least as well (relative to the national average) as it does the top students. It therefore seems reasonable to assume that XU's premedical program is successful because it increases the probability that students gain admission into health professional schools rather than because of any preselection of students. These results are similar to those obtained from a comparable analysis of XU's prepharmacy program, the other component of prehealth at Xavier.

Predictors of MCAT scores for black Americans.

If minority students likely to score low on the Medical College Admissions Test (MCAT) can be identified in advance, they can be advised to take existing preparatory programs, or programs can be developed to meet their needs. Correlation coefficients for a number of available independent variables with MCAT scores were determined for a population of premedical students at Xavier University of Louisiana. American College Testing (ACT) and Scholastic Aptitude Test (SAT) scores were found to have similar ability to predict MCAT scores, with a correlation coefficient of 0.64 between ACT composite and MCAT total scores. Correlations of sophomore year grade point average (GPA) with MCAT scores were only slightly weaker. Use of subtest scores for the ACT and SAT, grades in science courses, and Nelson-Denny Reading Test scores did not improve prediction to any real extent, either when used alone or in multiple linear regression analysis. In contrast to some previous studies, predictions for black men were as good as those for black women. Use of only ACT composite and sophomore year GPA together gave correlations only slightly weaker than predictions using a full range of variables; data from ACT composite and sophomore year GPA can be used for calculating predictive equations on many available micro-computers. These procedures may not be applicable to minority students at majority institutions.

Evidence of a soluble substrate for the receptor-destroying enzyme of influenza C virus.

Influenza C virus contains a hemagglutinin and a receptor-destroying enzyme (RDE) whose specificities remain undetermined. In rat serum, there is a molecule that binds specifically to C virus, inhibiting its hemagglutinin. The complex between C virus and the rat serum inhibitor (RSI) was determined to be stable at 4 degrees C, but was disrupted within 20 to 90 min at 23 or 37 degrees C. Virus emerged from the complex with numerous functions intact, whereas the RSI at this point was inactivated, i.e., incapable of further inhibitory reactions with C virus. RSI could not be inactivated at these temperatures by nonviral components of allantoic fluid of infected chicken embryos; however, RSI inactivation was achieved by preparations of sucrose gradient-purified virus. Neutralization of viral hemagglutination activity with antiviral antibody protected the RSI from inactivation. RSI inactivation occurred at temperatures at which the viral RDE was active, and inhibition of viral RDE by periodate treatment sharply reduced the ability of virus to inactivate the RSI. One interpretation of the data suggests that RSI is a receptor analog reactive with both the hemagglutinin and RDE of C virus and that RSI inactivation is an assay of influenza C viral RDE.

Human antibody to influenza C virus: its age-related distribution and distinction from receptor analogs.

Sera from persons of four age groups (1 to 2 years, 2 to 5 years, 20 to 30 years, and 65 to 85 years) were analyzed for hemagglutination inhibition (HI) activity for influenza C virus. Significant HI activity was found in 66% of the 237 sera tested, and titers ranged from 8 to 512. In the yoiung adult group, 96% had antibody and the highest mean titer (74.7) of any age group. Positive sera were far less common in young children (36 to 47%), and relatively low titers (18.3) were common among adults over 65. The high percentage of sera with antibody to influenza C virus suggests that infections with this virus occur at a rate greater than previously recognized. The high percentage of young adults with elevated levels of HI antibody suggested either that an immune response to influenza C infections is common or that the observed HI activity might be attributable, in part at least, to nonspecific inhibitors in the sera. We showed both directly and indirectly that most if not all the inhibitory activity in the human sera we examined was due to specific antibody, mostly immunoglobulin G. This conclusion is based on the finding that the single serum protein fraction with HI activity was found to have a molecular weight equivalent to that of 7S antibody (150,000) and that the HI activity was removed by absorption to staphyloccal protein A. Moreover, immunoglobulin from only HI-positive sera bound specifically to cells infected with influenza C virus, as shown by inhibition of hemadsorption and immunofluorescence. These findings were supported by similar results obtained with chicken antisera to C virus.

Properties of influenza C virus grown in cell culture.

Influenza C virus was propagated successfully in primary chicken embryo lung (CEL) and fibroblast cells and in Madin-Darby canine kidney (MDCK) cells. In other cell lines, either no virus or only noninfectious hemagglutinin (HA) was produced. In productively infected cells (CEL), HA and infectious virus appeared by 24 h and reached a maximum by 36 to 48 h, cell-associated virus remaining at a constant low level. Infected Vero cells produced noninfective HA by 24 h which also remained predominantly cell associated until 60 to 72 h, when the cells disintegrated. Viral antigen was demonstrable on membranes of both CEL- and Vero-infected cells at 24 h; Vero cells yielded membrane vesicles containing HA, but none of the spherical or filamentous viral particles synthesized in CEL cells. Influenza C virus produced in cell culture or in eggs differed in several important respects from A and B viruses and from Newcastle diseases virus. All influenza C preparations, regardless of infectivity or source, lacked detectable neuraminidase activity, yet retained the ability specifically to inactivate receptors only for influenza C. Influenza C HA was not inhibited by soluble glycoproteins highly active against HA of A virus. A rat serum glycoprotein uniquely inhibited influenza C by binding to the surface components of virious.

Transplantation of pluripotential nuclei from triploid frog tumors.

Renal tumors were produced by injection of a cell fraction of a tumor into triploid tadpoles of Rana pipiens before they began feeding. Triploid tumor cells were dissociated and transplanted into activated and enucleated eggs. Pluripotency of the implanted nuclei was evidenced by the formation of swimming triploid tadpoles.