6,021 research outputs found
The relationship between solar flares and solar sector boundaries
A superposed epoch analysis of 1964-1970 solar flares shows a marked increase in flare occurrence within a day of (-+) solar sector boundaries, as well as a local minimum in flare occurrence near (+-) sector boundaries. This perference for (-+) boundaries is more noticeable for Northern Hemisphere flares, where these polarities match the Hale polarity law, but is not reversed in the south. Plage regions do not show such a perference
"Virus hunting" using radial distance weighted discrimination
Motivated by the challenge of using DNA-seq data to identify viruses in human
blood samples, we propose a novel classification algorithm called "Radial
Distance Weighted Discrimination" (or Radial DWD). This classifier is designed
for binary classification, assuming one class is surrounded by the other class
in very diverse radial directions, which is seen to be typical for our virus
detection data. This separation of the 2 classes in multiple radial directions
naturally motivates the development of Radial DWD. While classical machine
learning methods such as the Support Vector Machine and linear Distance
Weighted Discrimination can sometimes give reasonable answers for a given data
set, their generalizability is severely compromised because of the linear
separating boundary. Radial DWD addresses this challenge by using a more
appropriate (in this particular case) spherical separating boundary.
Simulations show that for appropriate radial contexts, this gives much better
generalizability than linear methods, and also much better than conventional
kernel based (nonlinear) Support Vector Machines, because the latter methods
essentially use much of the information in the data for determining the shape
of the separating boundary. The effectiveness of Radial DWD is demonstrated for
real virus detection.Comment: Published at http://dx.doi.org/10.1214/15-AOAS869 in the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Raising Revenue for Persons with Disabilities
Whereas right-libertarians do not think that it is a requirement of justice that we raise revenues for persons with disabilities, both left-libertarians and liberal egalitarians think that there is such a requirement. An issue remains for the latter two theorists—how ought we to raise this revenue? Liberal egalitarians typically endorse either universal taxation or taxation of the wealthy. Left-libertarians, on the other hand, cannot so easily appeal to the methods of universal taxation and taxation of the wealthy, as they are illegitimately coercive. One such method left open to the left-libertarian is one proposed by Michael Otsuka. He argues that both left-libertarians and liberal egalitarians should find the method of taxation of the unjust to be a reasonably strong way of raising revenue. In this paper, I point out problems with Otsuka’s argument, as well as directly criticize the method of taxation of the unjust
Large-Scale periodic solar velocities: An observational study
Observations of large-scale solar velocities were made using the mean field telescope and Babcock magnetograph of the Stanford Solar Observatory. Observations were made in the magnetically insensitive ion line at 5124 A, with light from the center (limb) of the disk right (left) circularly polarized, so that the magnetograph measures the difference in wavelength between center and limb. Computer calculations are made of the wavelength difference produced by global pulsations for spherical harmonics up to second order and of the signal produced by displacing the solar image relative to polarizing optics or diffraction grating
Promoter switching allows simultaneous transcription of LANA and K14/vGPCR of Kaposi's sarcoma-associated herpesvirus
Latent transcription of the latency-associated nuclear antigen (LANA/ORF73) of Kaposi's sarcoma-associated herpesvirus is driven by the LANAp-c. Complexity arises during lytic reactivation, however, as the bicistronic K14/vGPCR transcript initiates 32 bp downstream of LANAp-c in the opposite orientation. We identify an Rta/ORF50-inducible LANA promoter (LANAp-i) that is distinct from the LANAp-c. LANAp-c is unaffected by Rta/ORF50. Utilization of the second, downstream LANAp-i explains how LANA and K14/vGPCR are simultaneously transcribed during de novo infection or lytic reactivation. Transactivation of LANAp-i and K14/vGPCRp requires the C-terminal activation domain of Rta/ORF50 and is mediated by DNA-binding-dependent and -independent Rta/ORF50 mechanisms. Transcriptional profiling following viral reactivation support promoter reporter phenotypes. In sum, -elements within the LANAp were selected to ensure faithful expression of LANA and other genes regulated by LANAp during all stages of the KSHV lifecycle despite potential interference from K14/vGPCRp activity
Liposomal daunorubicin as treatment for Kaposi’s sarcoma
Anthracycline compounds including daunorubicin are the foundation of many modern chemotherapeutic regimens. However, the side-effects of these compounds can be severe, leading to alopecia, nausea, immune deficiency, and cardiotoxicity. For immunocompromised patients with aggressive Kaposi’s sarcoma (KS), these complications often preclude the completion of appropriate chemotherapeutic regimens. This review focuses on the development and efficacy of liposomal daunorubicin (DaunoXome®; DNX) carriers for the treatment of KS. Encouragingly, DNX demonstrated increased in vivo stability and specificity. As a result, KS patients benefit from higher cumulative chemotherapeutic doses without significant cardiotoxicity. Tumor response to DNX treatment surpasses that of non-encapsulated daunorubicin and is similar to that observed with conventional multi-drug therapies such as ABV (doxorubicin, bleomycin, vincristine). Moreover, some reports indicate the patient quality of life during therapy may improve with DNX treatment. Although the development of DNX represents a significant advance in KS therapy, recent data suggest that additional modification of the liposomal carrier to include pegylation or target specific antibodies may further increase daunorubicin efficacy in the future
Viral effects on the content and function of extracellular vesicles
The release of membrane-bound vesicles from cells is being increasingly recognized as a mechanism of intercellular communication. Extracellular vesicles (EVs) or exosomes are produced by virus-infected cells and are thought to be involved in intercellular communication between infected and uninfected cells. Viruses, in particular oncogenic viruses and viruses that establish chronic infections, have been shown to modulate the production and content of EVs. Viral microRNAs, proteins and even entire virions can be incorporated into EVs, which can affect the immune recognition of viruses or modulate neighbouring cells. In this Review, we discuss the roles that EVs have during viral infection to either promote or restrict viral replication in target cells. We will also discuss our current understanding of the molecular mechanisms that underlie these roles, the potential consequences for the infected host and possible future diagnostic applications
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