Picosecond photodiffraction in semiconductor multiquantum wells and microcavities

We study the transient gratings photogenerated in the picosecond regime in three families of structures, namely : - structures of thickness in the order of one micron, including quantum wells (GaAs/GaAlAs, CdTe/ CdZnTe). A transmission modulation due to the electric field has been observed. We show that, in accordance with our calculations, this modulation is screened faster than 10 ps at a fluence of a few µJ/cm2. - A structure including GalnAs/GalnAsP MQWS in a cavity. This structure shows a top diffraction efficiency of 2.5 × 10-² at 1.55 µm for an energy of excitation in the order of 100 µJ/cm2. The diffraction efficiency exhibits several oscillations due to Fabry-Pårot effects. By introducing cavity effects in our model, we show that the diffraction efficiency is amplified by more than a factor 2 with respect to the no-cavity case. Calculations show that the diffraction efficiency may reach 6 × 10-² around 1.625 µm, for a front mirror reflectivity of 90 %. - Structures including bulk GaAs microcavities. The risetime is lower or in the order of 1 ps while the diffraction efficiency attains 1 %, with an average power of 4 mW (i.e. an energy of 2 µJ/cm²/pulse), compatible with a commutation of packets at 80 MHz.     

Identification of leek-moth and diamondback-moth frass volatiles that stimulate parasitoid,Diadromus pulchellus

Acrolepiopsis assectella andPlutella xylostella frass volatiles, trapped on Tenax GC, were examined by capillary gas chromatography. In both moths, the same three disulfides, dimethyl, dipropyl, and methyl propyl, were the most abundant substances, but in different proportions. The synthetic disulfides elicited the same behavioral response by the parasitoid,Diadromus pulchellus as frass. The plant origin of these substances is discussed.     

Density Displays for Data Stream Monitoring

In many business applications, large data workloads such as sales figures or process performance measures need to be monitored in real‐time. The data analysts want to catch problems in flight to reveal the root cause of anomalies. Immediate actions need to be taken before the problems become too expensive or consume too many resources. In the meantime, analysts need to have the “big picture” of what the information is about. In this paper, we derive and analyze two real‐time visualization techniques for managing density displays: (1) circular overlay d isplays which visualize large volumes of data without data shift movements after the display is full, thus freeing the analyst from adjusting the mental picture of the data after each data shift; and (2) variable resolution density displays which allow users to get the entire view without cluttering. We evaluate these techniques with respect to a number of evaluation measures, such as constancy of the display and usage of display space, and compare them to conventional d isplays with periodic shifts. Our real time data monitoring system also provides advanced interactions such as a local root cause analysis for further exploration. The applications using a number of real‐world data sets show the wide applicability and usefulness of our ideas.     

Experimental analysis and numerical modelling of the forming process of polypropylene replicas of micro-cavities using hot embossing

Numerical modelling of the deformation of a polymer using the finite elements method in axisymetrical mode was performed using the LsDyna^® software to describe the filling of micro-cavities during the forming process of the material using the hot embossing. These simulations firstly allow verifying whether the chosen forming process conditions promote or not an optimized filling of the superficial cavities in order to achieve precise replicas which best reproduce the superficial topography of the mould. The simulations were carried out to evaluate the filling of the cavities taking into account the mechanical behaviour of the selected polymer into the model. Moreover, these models were developed to verify the effect of the distribution of the mould cavities on their filling. The influence of the mobility of non deformable rigid plates on the filling of the cavities represents an auxiliary variable. In the approach presented, the compression plates are assumed to be parallel and non deformable, whereas the polymer disk follows a rubbery behaviour around a temperature equal to 140°C. Globally the modelling results are satisfactory for they are rather close to the experimental observations conducted. In summary, the effect of the normal stress as also the distribution of micro-cavities at the mould surface seem to prevail in the case of the forming process by hot embossing.     

Roll manufacturing of flexible microfluidic devices in thin PMMA and COC foils by embossing and lamination

Microfluidics on foil is gaining momentum due to a number of advantages of employing thin films combined with the capability of cost-effective high-volume manufacturing of devices. In this work, ultra-thin, flexible Y-microreactors with microchannels of 100 μm width and 30 μm depth were fabricated in thermoplastic polymer foils. The fluidic pattern was hot roll embossed in 125 μm thick poly-methyl-methacrylate (PMMA) and 130 μm thick cyclic-olefin-copolymer (COC) films using a dry-etched microstructured silicon wafer as a flat embossing tool in a laminator. The sealing of the channels was performed with two different techniques, one based on lamination of SU8 dry film resist (DFR) and the other one based on spin-coated poly-dimethylsiloxane (PDMS). Testing of the interconnected microreactor was carried out using two dye colorant solutions to demonstrate mixing.     

L'échelle de dramatisation face à la douleur PCS-CF: Adaptation canadienne en langue fran?aise de l'échelle Pain Catastrophizing Scale.

This study examined the psychometric properties of the PCS-CF, a French-Canadian adaptation of the Pain Catastrophizing Scale (Sullivan, Bishop & Pivik, 1995). One hundred and twenty undergraduate students (83 women; 37 men) completed the PCS-CF and measures of anxiety and depression prior to immersing their hand in ice water for 1-minute. A subset of 39 participants (28 females; 11 males) also completed a second pain task involving an ascending series of electrocutaneous stimulations. Participants' verbal and non-verbal pain behaviours during and immediately after the immersion task were recorded and subsequently independently coded. Reliability analyses revealed that the PCS-CF total score and subscale scores have a high degree of internal consistency and test-retest reliabilities that are comparable to the original Pain Catastrophizing Scale. PCS-CF scores were associated with higher levels of self-reported pain during the ice water immersion task and decreased pain tolerance during electrocutaneous stimulation. Individuals with elevated PCS-CF scores also displayed a more diverse repertoire of pain behaviours than their low PCS-CF counterparts. Previous findings that catastrophizing scores are able to discriminate criterion groups of males and females were also replicated. Given the highly correlated factors obtained in analyses of the dimensionality of the PCS-CF, the structure suggested by the authors of the original scale is only partially supported. However, the results taken together suggest that the PCS-CF is both a reliable and valid measure of the pain catastrophizing construct that is psychometrically comparable to the original PCS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pre-Omicron Vaccine Breakthrough Infection Induces Superior Cross-Neutralization against SARS-CoV-2 Omicron BA.1 Compared to Infection Alone

SARS-CoV-2 variants raise concern because of their high transmissibility and their ability to evade neutralizing antibodies elicited by prior infection or by vaccination. Here, we compared the neutralizing abilities of sera from 70 unvaccinated COVID-19 patients infected before the emergence of variants of concern (VOCs) and of 16 vaccine breakthrough infection (BTI) cases infected with Gamma or Delta against the ancestral B.1 strain, the Gamma, Delta and Omicron BA.1 VOCs using live virus. We further determined antibody levels against the Nucleocapsid (N) and full Spike proteins, the receptor-binding domain (RBD) and the N-terminal domain (NTD) of the Spike protein. Convalescent sera featured considerable variability in the neutralization of B.1 and in the cross-neutralization of different strains. Their neutralizing capacity moderately correlated with antibody levels against the Spike protein and the RBD. All but one convalescent serum failed to neutralize Omicron BA.1. Overall, convalescent sera from patients with moderate disease had higher antibody levels and displayed a higher neutralizing ability against all strains than patients with mild or severe forms of the disease. The sera from BTI cases fell into one of two categories: half the sera had a high neutralizing activity against the ancestral B.1 strain as well as against the infecting strain, while the other half had no or a very low neutralizing activity against all strains. Although antibody levels against the spike protein and the RBD were lower in BTI sera than in unvaccinated convalescent sera, most neutralizing sera also retained partial neutralizing activity against Omicron BA.1, suggestive of a better cross-neutralization and higher affinity of vaccine-elicited antibodies over virus-induced antibodies. Accordingly, the IC50: antibody level ratios were comparable for BTI and convalescent sera, but remained lower in the neutralizing convalescent sera from patients with moderate disease than in BTI sera. The neutralizing activity of BTI sera was strongly correlated with antibodies against the Spike protein and the RBD. Together, these findings highlight qualitative differences in antibody responses elicited by infection in vaccinated and unvaccinated individuals. They further indicate that breakthrough infection with a pre-Omicron variant boosts immunity and induces cross-neutralizing antibodies against different strains, including Omicron BA.1.     

Quantitative biology of single neurons

The building blocks of complex biological systems are single cells. Fundamental insights gained from single-cell analysis promise to provide the framework for understanding normal biological systems development as well as the limits on systems/cellular ability to respond to disease. The interplay of cells to create functional systems is not well understood. Until recently, the study of single cells has concentrated primarily on morphological and physiological characterization. With the application of new highly sensitive molecular and genomic technologies, the quantitative biochemistry of single cells is now accessible.     

Using immersive virtual reality and anatomically correct computer-generated characters in the forensic assessment of deviant sexual preferences

Penile plethysmography (PPG) is the gold standard for the assessment of sexual interests, especially among sex offenders of children. Nonetheless, this method faces some ethical limitations inherent to the nature of its stimuli and could benefit from the improvement of its ecological validity. The use of computer-generated characters (CGC) in virtual immersion for PPG assessment might help address these issues. A new application developed to design made-to-measure anatomically correct virtual characters compatible with the Tanner developmental stages is presented. The main purpose of this study was to determine how the virtual reality (VR) modality compares to the standard auditory modality on their capacity to generate sexual arousal profiles and deviance differentials indicative of sexual interests. The erectile responses of 22 sex offenders of children and 42 non-deviant adult males were recorded. While both stimulus modalities generated significantly different genital arousal profiles for sex offenders of children and non-deviant males, deviance differentials calculated from the VR modality allowed for significantly higher classification accuracy. Performing receiver operating characteristic analyses further assessed discriminant potential. Auditory modality yielded an area under the curve (AUC) of 0.79 (SE = 0.059) while CGC in VR yielded an AUC of 0.90 (SE = 0.052). Overall, results suggest that the VR modality allows significantly better group classification accuracy and discriminant validity than audio stimuli, which provide empirical support for the use of this new method for PPG assessment. Additionally, the potential use of VR in interventions pertaining to self-regulation of sexual offending is addressed in conclusion.