Исследование алгоритмов логического вывода

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Analysis and prediction of copper surface roughness obtained by selective laser melting

The paper presents the results of experimental studies of the effect of mechanoactivation of the powder, argon shielding gas and the effect of technological modes of melting: the speed of the laser beam, the power of laser radiation, the scanning step, the preliminary temperature of heating the powder material on the surface roughness of the copper powder material obtained by selective laser melting. Experiments on the melting of copper powder are implemented on the installation of layer-by-layer laser melting of the original design, which allows to adjust all technological modes of melting. The surface roughness is determined on the non-contact digital microscope Olympus LEXT OLS4100. The mathematical dependence of the surface layer roughness of copper powder on the technological modes of melting is obtained on the basis of the theory of experiment planning and static processing of the results. The significant parameters of the regime-the power of laser radiation, the speed of the laser beam, the scanning step affecting the roughness of the layer. The positive effect of mechanical activation of powder material and protective atmosphere on the quality of the surface layer is shown

Fluorescence-Guided Stereotactic Biopsy: A Proof-of-Concept Study

Introduction: Histopathological diagnoses are often necessary for treating neuro-oncology patients. However, stereotactic biopsy (STB), a common method for obtaining tissue from deep or eloquent brain regions, fails to yield diagnostic tissue in approximately 10% of cases. This can delay initiation of treatment and may result in further invasive procedures for patients. Here, we evaluate if coupling in vivo optical imaging with a STB system can identify diagnostic tissue at the time of biopsy. Methods: A minimally invasive fiber optic imaging system was developed by coupling a 0.65mm diameter fiber optic fluorescence microendoscope to a STB system. Human glioma cells were transduced for stable expression of blue fluorescent protein (U251-BFP) and utilized for in vitro and in vivo experiments. In vitro, blue fluorescence was confirmed, and tumor cell delineation by sodium fluorescein (FNa) was quantified with fluorescence microscopy. Rodent xenografts implanted with U251-BFP cells (n=4) were utilized for in vivo experiments. Five weeks post-implantation, xenografts received 5-10mg/kg intravenous FNa and underwent craniotomies overlying the tumor implantation site and contralateral normal brain. A clinical STB needle containing our 0.65mm imaging fiber was passed through each craniotomy and images were collected. Fluorescence images from regions of interest (ROI) ipsilateral and contralateral to tumor implantation were analyzed. Results: Live-cell fluorescence imaging confirmed blue fluorescence from transduced tumor cells and revealed a strong correlation between tumor cells quantified by blue fluorescence and FNa contrast (R2=0.91, p\u3c0.001). Normalized to background, in vivo FNa fluorescence intensity was significantly greater from tumor regions, verified by blue fluorescence, compared to contralateral brain in all animals (60.65± 17.35 %, p\u3c0.001). Fluorescein fluorescence was not significantly greater from the tumor margin compared to normal brain (p =0.096). Biopsies obtained from regions of strong fluorescein contrast were histologically consistent with tumor. Conclusion: We found in vivo fluorescence imaging with a STB needle containing a submillimeter diameter fluorescence microendoscope provided direct visualization of neoplastic tissue in an animal brain tumor model prior to biopsy. This was confirmed in vivo and by post-hoc histological assessment. In vivo fluorescence guidance may improve the diagnostic yield of stereotactic biopsies

RASER MRI: Magnetic resonance images formed spontaneously exploiting cooperative nonlinear interaction

The spatial resolution of magnetic resonance imaging (MRI) is limited by the width of Lorentzian point spread functions associated with the transverse relaxation rate 1/T2*. Here, we show a different contrast mechanism in MRI by establishing RASER (radio-frequency amplification by stimulated emission of radiation) in imaged media. RASER imaging bursts emerge out of noise and without applying radio-frequency pulses when placing spins with sufficient population inversion in a weak magnetic field gradient. Small local differences in initial population inversion density can create stronger image contrast than conventional MRI. This different contrast mechanism is based on the cooperative nonlinear interaction between all slices. On the other hand, the cooperative nonlinear interaction gives rise to imaging artifacts, such as amplitude distortions and side lobes outside of the imaging domain. Contrast mechanism and artifacts are explored experimentally and predicted by simulations on the basis of a proposed RASER MRI theory

Herpes Simplex Virus 1 and Chlamydophila (Chlamydia) pneumoniae promote Ab 1-42 amyloid processing in murine astrocytes linking an infectious process to Alzheimer\u27s disease

Background: Several studies have suggested an infectious etiology for Alzheimer\u27s disease (AD). Previously, our laboratory identified Chlamydia pneumoniae (Cpn) from autopsied sporadic AD brains, as well as developed a BALB/c mouse model that demonstrated infection-induced amyloid plaques similar to those found in AD. Hypothesis: We propose that an additional pathogen such as herpes simplex virus type 1 (HSV1), also may be a contributing factor in toin the pathology seen in AD. HSV1, in addition to Cpn, may be triggering the abnormal cleavage of the beta amyloid precursor protein (bAPP) into Ab1-42 , thereby contributing to amyloid plaque formation. Our current study examines amyloid processing following infection of primary and C8-DIA murine astrocytes with Cpn and HSV1. Materials and Methods: Immunocytochemistry and western analysis was used to analyze the outcome of infection by these two pathogens. Results: Cpn infection resulted in an increase in cytoplasmic labeling of Ab 1-42 relative to uninfected cells, while increased nuclear labeling of Ab 1-42 was observed following HSV1 infection. Co-infections with Cpn and HSV1 resulted in amyloid labeling resembling that of HSV1 infection alone, though Ab 1-42 labeling appeared decreased specifically in Cpn-infected cells of the co-infected monolayers. Conclusions: These data suggest that infection of astrocytic cells by HSV1 and (Cpn) alter the processing of bAPP, thereby producing Ab1-42. Therefore, these studies, inaddition to the previous research reported by our laboratory, support an emerging linkage of the infectious processs to the neuropathology characteristic of Alzheimer\u27s disease.https://digitalcommons.pcom.edu/posters/1008/thumbnail.jp

RASER MRI: Magnetic resonance images formed spontaneously exploiting cooperative nonlinear interaction

The spatial resolution of magnetic resonance imaging (MRI) is fundamentally limited by the width of Lorentzian point spread functions (PSF) associated with the exponential decay rate of transverse magnetization (1/T2*). Here we show a different contrast mechanism in MRI by establishing RASER (Radio-frequency Amplification by Stimulated Emission of Radiation) in imaged media. RASER imaging bursts emerge out of noise and without applying (Radio Frequency) RF pulses when placing spins with sufficient population inversion in a weak magnetic field gradient. A small difference in initial population inversion density creates a stronger image contrast than conventional MRI. This contrast is based on the cooperative nonlinear interaction between all slices. On the other hand, the cooperative nonlinear interaction gives rise to imaging artifacts, such as amplitude distortions and side lobes outside of the imaging domain. Both the contrast and the artifacts are demonstrated experimentally and predicted by simulations based on a proposed theory. This theory of RASER MRI is strongly connected to many other distinct fields related to synergetics and non-linear dynamics

Exploring synchrony and chaos of parahydrogen-pumped two-compartment radio-frequency amplification by stimulated emission of radiation

A nuclear-spin-based RASER (radio-frequency amplification by stimulated emission of radiation) is an ideal experimental system to explore nonlinear interaction phenomena of nuclear spins coupled via virtual photons to a resonator. This is due to the RASER being stable for several hours, allowing for extended observation of these phenomena. Nonlinear phenomena in multimode RASERs range from mode oscillations in synchrony, frequency shifts, frequency combs, period doublings, and even chaos. These phenomena are observed in a parahydrogen-pumped two-compartment proton RASER. In two independently pumped compartments, the separation in frequency space between the two RASER modes is precisely controlled with a magnetic field gradient. By controlling the mode separation, we can select the type of nonlinear phenomena observed. A key finding is that the ranges of mode separation where chaos and synchrony occur are very close together. The experimental results are supported by numerical simulations, based on two-mode RASER equations