37 research outputs found
Contrast improvement by using tailored laser pulses to circumvent undesired excitations
We report on fluorescence contrast improvement by using phase, amplitude, and polarization shaped laser pulses. The measurements were conducted by applying phase functions at different spectral amplitudes for excitations of dyes and agree very well with calculations. In particular, undesired one-photon excitations are circumvented with phase and amplitude tailored pulses for two-photon transition. This is realized by cutting out the laser spectrum at the wavelength of the one-photon process while utilizing an antisymmetric phase function that allows for constructive interference of the remaining outer spectral contributions for two-photon absorption. Moreover, polarization enhanced contrast between dyes is demonstrated where the two-photon dye is predominantly excited in one polarization direction and simultaneously the one-photon dye in the other polarization direction. The presented methods of shaping ultrashort laser pulses have a high potential for imaging applications
Combined temporal and spatial laser pulse shaping for two-photon excited fluorescence contrast improvement
We report on combined simultaneous temporal and spatial laser pulse shaping by utilizing light polarization properties. Thereto, a setup comprising a temporal pulse shaper, a waveplate, and a spatial shaper was developed and characterized by comparison with simulations. This enables to simultaneously shape one polarization component temporally and spatially while the perpendicular polarization component is modified temporally. The spatially and temporally modulated light fields were recorded and visualized by suitable contour plots, which was particularly demonstrated for cylindrically symmetric pulse profiles. Moreover, temporally and spatially shaped pulses were applied for two-photon excited fluorescence of dyes. These measurements were conducted by scanning third order phase functions for specific spatial pulse components which yields an enhanced contrast difference between fluorescing dyes. The presented temporal and spatial shaping method of ultrashort laser pulses has a high potential for biophotonic applications
Modifications of filament spectra by shaped octave-spanning laser pulses
In this paper we examine the spectral changes in a white light laser filament due to different pulse shapes generated by a pulse-shaping setup. We particularly explore how the properties of the filament spectra can be controlled by parametrically tailored white light pulses. The experiments are carried out in a gas cell with up to 9 bars of argon. Plasma generation and self-phase modulation strongly affect the pulse in the spectral and temporal domains. By exploiting these effects we show that the pulse spectrum can be modified in a desired way by either using second-order parametric chirp functions to shift the filament spectrum to higher or lower wavelengths, or by optimizing pulse shapes with a genetic algorithm to generate more complex filament spectra. This paper is an example of the application of complex, parametrically shaped white light pulses
T Cell Phenotype and T Cell Receptor Repertoire in Patients with Major Depressive Disorder
While a link between inflammation and the development of neuropsychiatric
disorders, including major depressive disorder (MDD) is supported by a growing
body of evidence, little is known about the contribution of aberrant adaptive
immunity in this context. Here, we conducted in-depth characterization of T
cell phenotype and T cell receptor (TCR) repertoire in MDD. For this cross-
sectional case–control study, we recruited antidepressant-free patients with
MDD without any somatic or psychiatric comorbidities (n = 20), who were
individually matched for sex, age, body mass index, and smoking status to a
non-depressed control subject (n = 20). T cell phenotype and repertoire were
interrogated using a combination of flow cytometry, gene expression analysis,
and next generation sequencing. T cells from MDD patients showed significantly
lower surface expression of the chemokine receptors CXCR3 and CCR6, which are
known to be central to T cell differentiation and trafficking. In addition, we
observed a shift within the CD4+ T cell compartment characterized by a higher
frequency of CD4+CD25highCD127low/− cells and higher FOXP3 mRNA expression in
purified CD4+ T cells obtained from patients with MDD. Finally, flow
cytometry-based TCR Vβ repertoire analysis indicated a less diverse CD4+ T
cell repertoire in MDD, which was corroborated by next generation sequencing
of the TCR β chain CDR3 region. Overall, these results suggest that T cell
phenotype and TCR utilization are skewed on several levels in patients with
MDD. Our study identifies putative cellular and molecular signatures of
dysregulated adaptive immunity and reinforces the notion that T cells are a
pathophysiologically relevant cell population in this disorder
Fluorescence anisotropy excitation by polarization-shaped laser pulses after transmission through a kagome fiber
We report improved fluorescence contrast between dyes by two-photon excitation
with polarization-shaped laser pulses after transmission through a kagome
fiber utilizing the anisotropy of the dye molecules. Particularly phase- and
polarization-tailored pulse shapes are employed for two-photon excited
fluorescence of dyes in a liquid environment at the distal end of the kagome
fiber. The distortions due to the optical fiber properties are precompensated
in order to receive predefined polarization-shaped laser pulses after the
kagome fiber. This enables to optimally excite one dye in one polarization
direction and simultaneously the other dye in the other polarization
direction. The presented method has a high potential for endoscopic
applications due to the unique properties of kagome fibers for guiding
ultrashort laser pulses
Isolation of Aggregatibacter aphrophilus from bronchoalveolar lavage in a paediatric patient presenting with haemoptysis
We report a rare case of non–cystic fibrosis bronchiectasis accompanied by protracted infection with Aggregatibacter aphrophilus in a 12-year-old boy with haemoptysis. Keywords: Aggregatibacter aphrophilus, BAL, bronchoscopy, HACEK, non-CF bronchiectasi
Isolation of Aggregatibacter aphrophilus from bronchoalveolar lavage in a paediatric patient presenting with haemoptysis
We report a rare case of non–cystic fibrosis bronchiectasis accompanied by protracted infection with Aggregatibacter aphrophilus in a 12-year-old boy with haemoptysis. © 201
Antimicrobial resistance of Yersinia enterocolitica and presence of plasmid pYV virulence genes in human and animal isolates
Interactions between bacterial virulence and antimicrobial resistance are of increasing interest in clinical microbiology. On this account, antimicrobial resistance of Yersinia enterocolitica O:3 strains isolated from humans (n = 55), food-chain animals (n = 58) and companion animals (n = 13) was determined in relation to the absence or presence of the pYV plasmid-encoded virulence genes yadA and virF. There were no statistically significant associations between the rate of antimicrobial resistance and the presence or absence of the plasmid, in either human-derived or animal-derived strains. Therefore, it can be concluded that response to conventionally used antimicrobials in Y. enterocolitica O:3 strains is not dependent on pYV-encoded virulence determinants. © 2019 The Author
Tribological behaviour of unveneered and veneered lithium disilicate dental material
The friction and wear behaviour of a lithium disilicate dental ceramic against natural dental enamel is studied, including the effect of the presence of a fluorapatite veneering upon the tribological properties of the material. The tribological behaviour was assessed using reciprocating pin-on-plate test configuration, at pH 3.and pH 7. The surface energy of the plates was determined, as well as the zeta potential of fluorapatite, lithium disilicate and enamel particles in artificial saliva. It was found that the friction and wear behaviour of the tested enamel/plate material tribocouples is less severe in unveneered plates. Initial surface roughness of the plate does not affect wear results. However the topography of the resulting wear track affects the corresponding wear loss: a smoother final wear track is associated with lower wear. The surface topography of the wear track, and thus the tribological performance of the tested materials, is very sensitive to the pH of the sliding solution. This is because the dissolution trend, wettability and surface charge of the used materials are pH dependent. Overall friction and wear are higher under basic pH conditions, especially when plates are veneered. A wear model is proposed that correlates the effect of the described parameters with the observed tribological behaviour at pH 7. Attained results show that fluorapatite coating of lithium disilicate dental crowns affects tooth/crown wear behaviour, resulting in increased wear of both the artificial crown and the opposing natural teeth. Coating should therefore be avoided in occlusal crown surfaces. (C) 2015 Elsevier Ltd. All rights reserved
Activation Cross Section Measurement of the (n,2n) Reaction on
The aim of the present work was to study the cross-section of the (n,2n) reaction on 203Tl, by irradiating a natural TlCl pellet target with monoenergetic neutron beams at 16.4, 18.9 and 19.3 MeV. The cross section of the 203Tl(n,2n)202Tl reaction was measured via the activation method, with respect to the 197Au(n,2n)196Au and 27Al(n,α)24Na reference reactions. At the same time, the 203Tl(n,3n)201Tl was also measured at 18.9 and 19.3 MeV. The monoenergetic neutron beams were generated at the 5.5 MV Tandem accelerator of NCSR “Demokritos”, using the 3H(d,n)4He reaction. In addition, theoretical calculations with the EMPIRE code have been performed, in order to find a suitable model for the description of the experimental data of the present work along with the data from literature