Use of photoacoustic excitation and laser vibrometry to remotely detect trace explosives.

In this paper, we examine a laser-based approach to remotely initiate, measure, and differentiate acoustic and vibrational emissions from trace quantities of explosive materials against their environment. Using a pulsed ultraviolet laser (266 nm), we induce a significant (>100 Pa) photoacoustic response from small quantities of military-grade explosives. The photoacoustic signal, with frequencies predominantly between 100 and 500 kHz, is detected remotely via a wideband laser Doppler vibrometer. This two-laser system can be used to rapidly detect and discriminate explosives from ordinary background materials, which have significantly weaker photoacoustic response. A 100 ng/cm2 limit of detection is estimated. Photoablation is proposed as the dominant mechanism for the large photoacoustic signals generated by explosives.

Current trends in the management of glioblastoma in a French University Hospital and associated direct costs.

WHAT IS NEW AND OBJECTIVES: Trends in the care of glioblastoma in actual practice settings are poorly described. In a previous pharmacoepidemiologic study, we highlighted changes in the management of patients with glioblastoma (GBM) newly diagnosed between 2004 and 2008. Our aim was to complete and to extend the previous report with a study of a cohort of patients diagnosed in 2011 to emphasize the trends in the pharmacotherapy of GBM over the last decade. METHODS: A single-centre study was undertaken of three historic cohorts of GBM patients newly diagnosed during years 2004, 2008 and 2011 (corresponding to groups 1, 2 and 3, respectively) but limited to patients eligible for radiotherapy after initial diagnosis. The type of medical management was described and compared, as well as overall survival and total cost from diagnosis to death or the last follow-up date. Cost analysis was performed from the French sickness fund perspective using tariffs from 2014. RESULTS: Two hundred and seventeen patients (49 in Group 1, 73 in Group 2, 95 in Group 3) were selected with similar baseline characteristics. Fluorescence-guided surgery using 5-ALA was increasingly used over the three periods. There was a strong trend towards broader use of temozolomide radiochemotherapy (39%, 73% and 83% of patients, respectively) as first-line treatment as well as bevacizumab regimen at recurrence (6%, 48% and 58% of patients, respectively). The increase in overall survival between Group 2 and Group 1 was confirmed for patients in Group 3 (17·5 months vs. 10 months in Group 1). The mean total cost per patient was 53368 € in Group 1, 70 201 € in Group 2 and 78355 € in Group 3. Hospital care represented the largest expenditure (75%, 59% and 60% in groups 1, 2 and 3, respectively) followed by chemotherapy drug costs (11%, 30% and 29%, respectively). WHAT IS NEW AND CONCLUSION: This is the first study to report on changes in the management of GBM in real-life practice. The ten-year study indicates an improvement in overall survival but also an increase in total cost of care. The data should be useful for informing the care of GBM patients in settings similar to ours.

Management of glioblastoma: comparison of clinical practices and cost-effectiveness in two cohorts of patients (2008 versus 2004) diagnosed in a French university hospital.

WHAT IS KNOWN AND OBJECTIVE: Therapeutic options for the management of glioblastoma (GBM) have greatly evolved over the last decade with the emergence of new regimens combining radiotherapy plus temozolomide and the use of bevacizumab at recurrence. Our aim was to assess the clinical and economic impacts of those novel strategies in our center. METHODS: A single-center retrospective chart review was conducted on patients newly diagnosed with a GBM over two periods (year 2004, group 1 or year 2008, group 2) with limitations to those eligible to radiotherapy after initial diagnosis. The type of medical management was described and compared, as well as overall survival and total costs from diagnosis to death or the last follow-up date. Cost analysis was performed under the French Sickness Fund perspective using tariffs from 2012. RESULTS: One hundred twenty-two patients were selected (49 in group 1 and 73 in group 2) with similar baseline characteristics within the two groups. Patients from group 2 received more frequently temozolomide radiochemotherapy (71% vs. 39%, P < 0·05) as first-line treatment as well as bevacizumab regimen at recurrence (48% vs. 6%, P < 0·05); the median overall survival was increased between the two periods (respectively 17 vs. 10 months, P < 0·05). The mean total cost per patient was 54,388 € in group 1 and 71,148 € in group 2 (P < 0·05). Hospital care represented the largest expenditure (76% and 58% in groups 1 and 2 respectively) followed by chemotherapy drugs costs (11% and 30% respectively). The total cost difference between the two groups was explained by the increasing use of temozolomide and bevacizumab. The incremental cost-effectiveness ratio was estimated at 54,355 € per life-year gained. WHAT IS NEW AND CONCLUSION: As far as we know, this is the first study reporting the total cost of GBM management based on the French perspective, as well as the cost-effectiveness of clinical practices in term of cost per life-year gained. Those novel strategies have contributed to improve overall survival while inducing a substantial, but acceptable, increase of total costs.

Supplementation of xylanase and phospholipase to wheat-based diets for weaner pigs.

The effects of supplementing a wheat-based diet for weaner pigs with exogenous xylanase and phospholipase on ileal and faecal nutrient digestibilities and on the level of microbial metabolites in ileal digesta were examined. Fourteen piglets, weaned at 11 days, were fitted with a simple T-cannula at the distal ileum. The pigs were offered a control diet or diets supplemented with xylanase and phospholipase individually or in combination, in a two period crossover design. The combination of xylanase and phospholipase tended to increase the ileal recovery of the amino sugar galactosamine, whereas the concentration expressed in mg/kg dry matter intake of glucosamine was slightly decreased (p < 0.10). There was neither an effect of enzyme supplementation on ileal and faecal digestibility of the other nutrients and energy, nor was there an effect on pH and on the level of microbial metabolites in ileal digesta. However, an increase in ileal and faecal nutrient and energy digestibility with increasing age was observed. The ileal and faecal digestibility coefficients (except for ether extract) were significantly (p < 0.05) higher in experimental period I than in period II. These higher values may be attributed to a lower feed intake during period I. Since a lower level of feed intake is generally associated with a slower rate of passage and a longer retention time of digesta, a positive impact on digestion and absorption of nutrients can be assumed, which, on the other hand, limits the potential of additional enzyme effects.

Effect of supplementation of xylanase and phospholipase to a wheat-based diet for weanling pigs on nutrient digestibility and concentrations of microbial metabolites in ileal digesta and feces.

The objective of this study was to determine the effect of supplementing a wheat-based diet with xylanase and phospholipase either alone or in combination on the ileal and fecal digestibilities of nutrients and energy in early-weaned pigs. In addition, the concentrations of ammonia, lactate, and VFA were measured in ileal digesta and feces. The experiment was carried out with 16 barrows weaned at the age of 11 d with an average initial BW of 4.1 kg. On d 4 and 5 postweaning, the piglets were fitted with a simple T-cannula at the distal ileum. The experiment was designed as a balanced incomplete block design with three periods. The piglets received the basal diet with or without supplementation of either xylanase or phospholipase or a combination of these. There was a positive (P = 0.005 to 0.018) effect on the digestibility values of GE, OM, CP, crude fiber (CF), and NDF with xylanase supplementation. Apart from lysine, threonine, cysteine, glycine, and proline, the digestibility values of all AA were improved (P = 0.001 to 0.024). Phospholipase supplementation had a positive effect on CP (P = 0.047) and CF (P = 0.002) digestibilities, but no effect on ether extract (EE) digestibility. Supplementation of both enzymes showed the largest response in nutrient digestibilities, except that EE digestibility was not affected. No differences were found in D-/L- lactate, and ammonia concentrations among treatments. Acetate and propionate concentrations tended to increase when xylanase was supplemented and were highest for the combination of both enzymes. Despite the positive effects on ileal nutrient and energy digestibilities, there was no effect of xylanase or the combined enzyme supplementation on the fecal digestibilities of OM, CP, EE, CF, NDF, ADF, or GE, and on fecal concentrations of VFA. Phospholipase alone slightly decreased the total-tract nutrient and energy digestibilities (P < 0.05). In conclusion, the combination of both enzymes generally led to the highest increases in ileal digestibilities, which were of small numerical magnitude (approximately 2%). However, on a relative basis, this increase of 2% represents approximately 13% of the remaining diet that was available for digestion based on the fact that approximately 15% of the diet was not digested in the control pigs. Thus, the potential benefits in the nutrition of weanling pigs from combinations of enzymes should be validated under practical conditions.

Photoacoustic point source.

We investigate the photoacoustic effect generated by heat deposition at a point in space in an inviscid fluid. Delta-function and long Gaussian optical pulses are used as sources in the wave equation for the displacement potential to determine the fluid motion. The linear sound-generation mechanism gives bipolar photoacoustic waves, whereas the nonlinear mechanism produces asymmetric tripolar waves. The salient features of the photoacoustic point source are that rapid heat deposition and nonlinear thermal expansion dominate the production of ultrasound.

Diffraction of light from phase gratings at large modulation depths: transient-grating experiments in liquids at high laser powers.

Generation of transient gratings in weakly absorbing liquids with a high-power laser gives rise to changes in the fluid's index of refraction that are sufficiently large to produce both multiple diffraction of a probe laser beam and a time response anomaly. The coupled-wave approach to the solution of the volume diffraction problem is shown to predict the existence of high-order diffraction of the probe beam and the time dependence of the diffraction intensity of each order. In addition, criteria for the Raman-Nath and Bragg diffraction regimes are derived from the first-order, coupled-wave equations.

[In pursuit of an object]. / A la poursuite de l'objet.

The author proposes an extension of the transitional phenomenon concept. Beginning with Winnicott's well known description, the author reviews the successive transformations of transitional space, first materialized and then increasingly "intrapsychic" and which persists in the individual all life long in various forms. Transformations go from the gross blanket to a more figurative little bear, then to play activities, creative drawing of the child, and finally to hypotheses and theories. This progressive hold on the object involves the mediation of transitional space--first found then created--and is instrumented through age-specific different means: concrete handling; certain characteristics of baby-talk such as voice intonation, use of the past tense before playing and the conditional in playing; redundancies, parentheses and abstractions. In the course of this paper, the author gives his personal view on the subtle differences between figuration and representation, and on the relationship between abstraction and aesthetical feeling.

Photoacoustic "signatures" of particulate matter: optical production of acoustic monopole radiation.

Absorption of pulsed laser radiation by a single particle generates a photoacoustic wave whose time profile can be measured with a wideband pressure transducer. Solution of the wave equation for pressure in one, two, and three dimensions shows that the photoacoustic wave is determined by the geometry and dimensions of the particle, and by its sound speed and density relative to the fluid that surrounds it. Photoacoustic waves, referred to here as signatures, are reported in experiments in which fluid droplets, cylinders, and layers are irradiated with 10-nanosecond laser pulses.

Photoacoustic generation of anisotropic pressure waves through photodissociation of Cl(2).

Photodissociation of diatomic molecules by linearly polarized radiation in general produces an anisotropic distribution of recoiling atomic fragments. When a short burst of radiation dissociates a gas at low pressure, the collective linear momenta of the individual recoiling photofragments add at any point in space to act as a macroscopic pressure wave, the impulse corresponding to which can be detected by a sensitive microphone. We report here detection of anisotropic pressure waves from photodissociation of Cl(2) with 355-nm radiation. The experimental data show the pressure wave to be peaked in a direction perpendicular to the polarization direction of the incident radiation, indicating a predominantly perpendicular transition moment in Cl(2) at this wavelength.

[Epilepsy, mourning and psychotherapy]. / Epilepsies, deuils et psychothérapies.

The authors, starts with the apparent generalized lack of sense, the non sense, about everything to do with epilepsy; he tries to understand the meaning of this excess of non sense. He first tries to find the possible utility for the psychic economy of the patient and his environment. Then, based on beginnings of meaning which do emerge, particularly at the time of the first crisis, he sketches the broad lines for a possible framework of psychotherapy; this is followed by a more theoretical discussion. This attempted synthesis is based in particular on the frequency of observations of the patient's identification with a double of his death. The author adopts for his purpose the concept of the crypt from which is derived the notion of the double of the self. Finally, a hypothesis is proposed which aims at understanding the mechanism of the constitution of this double, based on the family secret. To construct this hypothesis the author uses the comparison between real and imaginary doubles, trying to find in that the sense of the lack of sense.

Laser schlieren microphone for optoacoustic spectroscopy.

This paper describes a laser schlieren microphone, where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on an optoacoustic Helmholtz resonator. The sinusoidal pressure variations in the resonator distort the surface of the diaphragm so that the reflected laser beam is alternately focused and defocused. The deflection is converted into an amplitude modulation of the beam by an iris located at a distance from the resonator and detected with a photodiode. The light beam can be modulated at a high frequency and the signal from the photodiode processed with a lock-in amplifier so that noise with a power spectral density proportional to the inverse of the frequency is significantly reduced in the final optoacoustic signal. A mathematical description of the laser schlieren microphone is given that shows the system to respond linearly to small signals. An experiment was done to determine the range of linear response of the microphone to large amplitude optoacoustic signals.

Laser fluorometric determination of aflatoxin B1 in corn.

A 2-step chromatographic separation, using both thin layer chromatography (TLC) and high pressure liquid chromatography (HPLC), in conjunction with the high sensitivity of laser fluorometry permits extension of the detection limits of aflatoxin contamination in corn to 0.1 ppb (microgram/kg) with a 26% root mean square variation. Aflatoxin B1 is extracted from corn with water-methanol and cleaned up by TLC. The recovery of aflatoxin from the TLC plates was linear from 10 to 1000 pg. Aflatoxin B1 is converted to the more highly fluorescent B2A derivative by treatment with 1N HCl. Experiments with aflatoxin B1 standard establish a constant conversion to B2A over approximately 3 orders of magnitude in B1 concentration. An extract of the B2A aflatoxin derivative is injected onto a reverse phase HPLC column. A flowing droplet of eluant is irradiated by an amplitude-modulated 325 nm He-Cd ion laser beam, and fluorescence from the droplet is detected by a lock-in amplifier in phase with the laser modulation. Several chromatograms are presented that demonstrate the capability of this procedure for removing interfering components in the corn extract.

Noise reduction in EPR discharge-flow studies.

In discharge-flow systems employing electron paramagnetic resonance detection, intense spectrometer noise is present under certain conditions. This noise is due to free electrons produced in the discharge and can be eliminated by the addition of an electron scavenger to the flow. Using SF6 to suppress the noise, EPR spectroscopy can be used to identify and study transient species within a millisecond after their formation in an electrical discharge.