9,628 research outputs found
The Existence of Sterile Neutrino Halos in Galactic Centers as an Explanation of the Black Hole mass - Velocity Dispersion Relation
If sterile neutrinos exist and form halos in galactic centers, they can give
rise to observational consequences. In particular, the sterile neutrinos decay
radiatively and heat up the gas in the protogalaxy to achieve hydrostatic
equilibrium, and they provide the mass to form supermassive blackholes. A
natural correlation between the blackhole mass and velocity dispersion thus
arises with and .Comment: Accepted in Ap
Localisation of the melanocortin-2-receptor and its accessory proteins in the developing and adult adrenal gland
The melanocortin-2-receptor (MC2R)/MC2R accessory protein (MRAP) complex is critical to the production of glucocorticoids from the adrenal cortex. Inactivating mutations in either MC2R or MRAP result in the clinical condition familial glucocorticoid deficiency. The localisation of MC2R together with MRAP within the adrenal gland has not previously been reported. Furthermore, MRAP2, a paralogue of MRAP, has been shown in vitro to have a similar function to MRAP, facilitating MC2R trafficking and responsiveness to ACTH. Despite similar MC2R accessory functions, in vivo, patients with inactivating mutations of MRAP fail to be rescued by a functioning MRAP2 gene, suggesting differences in adrenal expression, localisation and/or function between the two MRAPs. In this study on the rat adrenal gland, we demonstrate that while MRAP and MC2R are highly expressed in the zona fasciculata, MRAP2 is expressed throughout the adrenal cortex in low quantities. In the developing adrenal gland, both MRAP and MRAP2 are equally well expressed. The MC2R/MRAP2 complex requires much higher concentrations of ACTH to activate compared with the MC2R/MRAP complex. Interestingly, expression of MC2R and MRAP in the undifferentiated zone would support the notion that ACTH may play an important role in adrenal cell differentiation and maintenance
Novel separation and detection methods of DNA fragments in electrophoresis
A charge-coupled device (CCD) based electrophoresis system was developed. The system allowed non-destructive, sensitive, and on-line detection of native DNA in slab-gel electrophoresis via ultraviolet absorption measurement. The detection limit of double-stranded DNA fragment was 5 ng per band. Since the amount of DNA used in this experiment was typical, the CCD-based system could be readily implemented in molecular biology;Gel-filled and non-gel sieving capillary electrophoresis (CE) was developed for rapid and efficient separation of double-stranded DNA fragments. For the gel-filled CE separation a new gel matrix, the HydroLink gel (HL), was used. The HL capillary gel was easier to cast than the polyacrylamide capillary gel. For the non-gel separation, a GC capillary was used as the separation chamber, and cellulose additive was included in the electrophoresis as the sieving medium;Indirect fluorometry was applied in non-gel and gel electrophoresis for the detection of DNA fragments. This method allowed non-destructive and on-line detection of DNA during electrophoresis. The amount of DNA used with this method was comparable to those obtained with absorption measurement
Characterization of unburned carbon content in coal fly ash with dielectric constant measurement
The research was to investigate the relationship between the dielectric constant of fly ash and the unburned carbon content in fly ash. Dielectric constant is a factor that measures the ratio of the permittivity of dielectric material to the permittivity of free space (8.85 x 10−12F/m). It describes the extent to which dielectric material interacts with electric flux. The dielectric constant of fly ash can be extracted from phase measurement using a network analyzer and a fixture based on coaxial transmission line design. Unburned carbon in fly ash is a major index to determine the efficiency of coal combustion in a power plant. Loss-on-ignition (LOI) technique and thermogravimetric analysis (TGA) are among the techniques being used in the industry to determine unburned carbon content in fly ash. Measuring dielectric constant of fly ash approach is promising as an alternative, non-destructive way to determine the amount of unburned carbon in fly ash. The Clausius-Mossotti relation is used to determine fly ash properties, including the dielectric constant, and therefore determines the unburned carbon content. The initial experiment shows the unburned carbon content estimated from dielectric constant measurement correlates closely to the unburned carbon content measured with the LOI technique
A Study of Attention-Free and Attentional Methods for LiDAR and 4D Radar Object Detection in Self-Driving Applications
In this thesis, we re-examine the problem of 3D object detection in the context of self driving cars with the first publicly released View of Delft (VoD) dataset [1] containing 4D radar sensor data. 4D radar is a novel sensor that provides velocity and Radar Cross Section (RCS) information in addition to position for its point cloud. State of the art architectures such as 3DETR [2] and IASSD [3] were used as a baseline. Several attention-free methods, like point cloud concatenation, feature propagation and feature fusion with MLP, as well as attentional methods utilizing cross attention, were tested to determine how we can best combine LiDAR and radar to develop a multimodal detection architecture that outperforms the baseline architectures trained only on either modality alone. Our findings indicate that while attention-free methods did not consistently surpass the baseline performance across all classes, they did lead to notable performance gains for specific classes. Furthermore, we found that attentional methods faced challenges due to the sparsity of radar point clouds and duplicated features, which limited the efficacy of the crossattention mechanism. These findings highlight potential avenues for future research to refine and improve upon attentional methods in the context of 3D object detection
Governance Methods Used in Externalizing Information Technology
Information technology (IT) is the largest capital expenditure in many firms and is an integral part of many organizations\u27 strategies. However, the benefits that each company receives from its IT investments vary. One study by Weill (2004) found that the top performer in the sample was estimated to have as high as a 40 greater return on its IT investment than its competitors. To expedite the progress toward getting better value from IT investments, along with the need to deal with the increasing complexity and expense of IT, a growing number of companies are turning to outside service providers to develop and/or manage various aspects of their information systems. The governance methods used by firms to maintain control over the quality, services, and cost of IT outsourcing are the focus of this dissertation.Previously in the literature, researchers have looked into the phenomenon of outsourcing from various perspectives. However, existing literature has not constructed or proposed an outsourcing model that examines the important moderating impact of internal technical capabilities to governance mechanisms. Building on existing literature related to IT outsourcing, this dissertation examines governance mechanisms that were used by firms to maintain control over the quality, services, and the cost of outsourcing of IT in order to identify their contribution to the success of IT outsourcing initiatives from the perspective of managers whose companies have engaged in IT outsourcing. In this dissertation, a research model was developed, and through an on-line survey instrument, data were collected from the members of the Information Systems Community of Practice in the Project Management Institute. The findings showed that the following governance mechanisms had positive impact on managerial perceptions of IT outsourcing success: (1) Financial commitment in the form of dedicated asset-specific investments and (2) attitudinal commitment. This study also confirms the moderation effect that firm technological capab
- …