Abstract Traumatic brain injury (TBI) can result in long-lasting changes in hippocampal function. The changes induced by TBI on the hippocampus contribute to cognitive deficits. The adult hippocampus ...harbors neural stem cells (NSCs) that generate neurons (neurogenesis), and astrocytes (astrogliogenesis). While deregulation of hippocampal NSCs and neurogenesis have been observed after TBI, it is not known how TBI may affect hippocampal astrogliogenesis. Using a controlled cortical impact model of TBI in male mice, single cell RNA sequencing and spatial transcriptomics, we assessed how TBI affected hippocampal NSCs and the neuronal and astroglial lineages derived from them. We observe an increase in NSC-derived neuronal cells and a concomitant decrease in NSC-derived astrocytic cells, together with changes in gene expression and cell dysplasia within the dentate gyrus. Here, we show that TBI modifies NSC fate to promote neurogenesis at the cost of astrogliogenesis and identify specific cell populations as possible targets to counteract TBI-induced cellular changes in the adult hippocampus.
The upgrades of the CMS and ATLAS experiments for the high luminosity phase of the Large Hadron Collider will employ precision timing detectors based on Low Gain Avalanche Detectors (LGADs). We ...present a suite of results combining measurements from the Fermilab Test Beam Facility, a beta source telescope, and a probe station, allowing full characterization of the HPK type 3.1 production of LGAD prototypes developed for these detectors. We demonstrate that the LGAD response to high energy test beam particles is accurately reproduced with a beta source. We further establish that probe station measurements of the gain implant accurately predict the particle response and operating parameters of each sensor, and conclude that the uniformity of the gain implant in this production is sufficient to produce full-sized sensors for the ATLAS and CMS timing detectors.
Buried Layer Low Gain Avalanche Diodes Apresyan, A.; Giacomini, G.; Heller, R. ...
Journal of physics. Conference series,
11/2022, Letnik:
2374, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We report on the design, simulation and test of Low Gain Avalanche Diodes (LGADs) which utilize a buried gain layer. The buried layer is formed by patterned implantation of a 50-micron thick float ...zone substrate wafer-bonded to a low resistivity carrier. This is then followed by epitaxial deposition of a ≈ 3 micron-thick high resistivity amplification region. The topside is then processed with junction edge termination and guard ring structures and incorporates an AC-coupled cathode implant. This design allows for independent adjustment of gain layer depth and density, increasing design flexibility. A higher gain layer dopant density can also be achieved by controlling the process thermal budget, improving radiation hardness. A first set of demonstration devices has been fabricated, including a variety of test structures. We report on TCAD design and simulation, fabrication process flow, and preliminary measurements of prototype devices.
We compared several generalizations of the Bruggeman effective medium approach with the use of elliptical cells. Namely, a “uniaxial” anisotropic approximation and two isotropic models with averaging ...over chaotic orientations and random conductivities of particles were compared, which make it possible to consider multicomponent composites with various filler particles (for instance, carbon nanotubes and graphenes). The expressions for the corresponding percolation thresholds were derived. It was shown that all considered approximations result in the same “additive rule” of the inverse percolation thresholds, which was previously found for a particular case of two-component fillers with the use of estimates of an excluded volume. The correlation of the aforementioned “additive rule” with frequently observed synergic effects was discussed, the description of which requires taking into account near correlations and is beyond purview of the effective medium theories. For the model problem with parameters corresponding to carbon nanotubes in a polymer matrix, the considered models led to qualitatively similar results and resulted in an effective conductivity within the Hashin−Shtrikman bounds. Using the known two-scale averaging technique, taking into account the possibility of agglomeration of the filler particles, we showed that, in the framework of the considered models, agglomeration can lead to both an increase and decrease in the percolation threshold.
Future calorimeters and shower maximum detectors at high luminosity colliders need to be highly radiation resistant and very fast. One exciting option for such a detector is a calorimeter composed of ...a secondary emitter as the active element. In this report we outline the study and development of a secondary emission calorimeter prototype using micro-channel plates (MCP) as the active element, which directly amplify the electromagnetic shower signal. We demonstrate the feasibility of using a bare MCP within an inexpensive and robust housing without the need for any photo cathode, which is a key requirement for high radiation tolerance. Test beam measurements of the prototype were performed with 120 GeV primary protons and secondary beams at the Fermilab Test Beam Facility, demonstrating basic calorimetric measurements and precision timing capabilities. Using multiple pixel readout on the MCP, we demonstrate a transverse spatial resolution of 0.8 mm, and time resolution better than 40 ps for electromagnetic showers.
Purpose of the study.
To assess the sensitivity, specificity and diagnostic accuracy of the method for non-invasive differential diagnosis of liver diseases by polyhepatography.
Materials and ...methods.
A random sampling method examined 45 primary patients. Polygepatography was performed on all patients to detect disorders of intrahepatic microcirculation during primary contacting. Based on the detected changes in intrahepatic hemodynamics and based on the morphofunctional hemodynamic model, a conclusion was made about the violation of intrahepatic blood flow and an assumption was made about the etiology and stage of liver disease. Subsequently, the diagnosis of liver diseases was verified after a detailed study of clinical-laboratory, instrumental and morphological data generally accepted in hepatology. Puncture liver biopsy by the Mancini method was performed in 11.1 % of the subjects.
Results.
All subjects were divided into three groups based on the data obtained on impaired intrahepatic hemodynamics during polyhepatography (PHG). The group I consisted of patients with impaired venous inflow, the group II included patients with impaired arteriovenous inflow, and group III — with impaired venous outflow. The obtained polyhepatographic data were compared with the results of clinical-laboratory, instrumental and morphological data. The high sensitivity, sufficient specificity and accuracy of the polyhepatography method in the diagnosis of chronic liver diseases have been determined.
Conclusion.
The studies carried out indicate that PHG is a simple, accessible and not burdensome examination method for the patient, which makes it possible to assess the localization of intrahepatic blood flow disorders, and, with a certain degree of probability, to assume the etiological factor of the disease and the stage of the disease. Given the specificity of changes in liver hemodynamics, de pending on the etiological factor and stage of the disease, assessment of intrahepatic hemodynamics by polyhepatography can be recommended as a screening method for examining patients with liver diseases, which will shorten the diagnostic search time.
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