University of California

About: University of California is a education organization based out in Oakland, California, United States. It is known for research contribution in the topics: Population & Layer (electronics). The organization has 55175 authors who have published 52933 publications receiving 1491169 citations. The organization is also known as: UC & University of California System.

Complex history of the amphibian-killing chytrid fungus revealed with genome resequencing data

Abstract: Understanding the evolutionary history of microbial pathogens is critical for mitigating the impacts of emerging infectious diseases on economically and ecologically important host species. We used a genome resequencing approach to resolve the evolutionary history of an important microbial pathogen, the chytrid Batrachochytrium dendrobatidis (Bd), which has been implicated in amphibian declines worldwide. We sequenced the genomes of 29 isolates of Bd from around the world, with an emphasis on North, Central, and South America because of the devastating effect that Bd has had on amphibian populations in the New World. We found a substantial amount of evolutionary complexity in Bd with deep phylogenetic diversity that predates observed global amphibian declines. By investigating the entire genome, we found that even the most recently evolved Bd clade (termed the global panzootic lineage) contained more genetic variation than previously reported. We also found dramatic differences among isolates and among genomic regions in chromosomal copy number and patterns of heterozygosity, suggesting complex and heterogeneous genome dynamics. Finally, we report evidence for selection acting on the Bd genome, supporting the hypothesis that protease genes are important in evolutionary transitions in this group. Bd is considered an emerging pathogen because of its recent effects on amphibians, but our data indicate that it has a complex evolutionary history that predates recent disease outbreaks. Therefore, it is important to consider the contemporary effects of Bd in a broader evolutionary context and identify specific mechanisms that may have led to shifts in virulence in this system.

Efficient and Accurate MRI Super-Resolution Using a Generative Adversarial Network and 3D Multi-level Densely Connected Network

Abstract: High-resolution (HR) magnetic resonance images (MRI) provide detailed anatomical information important for clinical application and quantitative image analysis. However, HR MRI conventionally comes at the cost of longer scan time, smaller spatial coverage, and lower signal-to-noise ratio (SNR). Recent studies have shown that single image super-resolution (SISR), a technique to recover HR details from one single low-resolution (LR) input image, could provide high quality image details with the help of advanced deep convolutional neural networks (CNN). However, deep neural networks consume memory heavily and run slowly, especially in 3D settings. In this paper, we propose a novel 3D neural network design, namely a multi-level densely connected super-resolution network (mDCSRN) with generative adversarial network (GAN)–guided training. The mDCSRN trains and inferences quickly, and the GAN promotes realistic output hardly distinguishable from original HR images. Our results from experiments on a dataset with 1,113 subjects shows that our new architecture outperforms other popular deep learning methods in recovering 4x resolution-downgraded images and runs 6x faster.

Clinical implications of aging skin: cutaneous disorders in the elderly.

Abstract: Aging skin undergoes progressive degenerative change. Structural and physiologic changes that occur as a natural consequence of intrinsic aging combined with the effects of a lifetime of ongoing cumulative extrinsic damage and environment insult (e.g. overexposure to solar radiation) can produce a marked susceptibility to dermatologic disorders in the elderly. As skin ages, the vasculature progressively atrophies. The supporting dermis also deteriorates, with collagen and elastin fibers becoming sparse and increasingly disordered. These changes leave the elderly increasingly susceptible to both vascular disorders such as stasis dermatitis and skin injuries such as pressure ulcers and skin tears, with a steadily decreasing ability to effect skin repair. A parallel erosion of normal immune function produces higher levels of autoimmune skin disorders such as bullous pemphigoid, benign mucous membrane pemphigoid, paraneoplastic pemphigoid, and pemphigus vulgaris. Lichen sclerosus, an autoimmune disorder often occurring in the genital area in older women, is not common but is an important development because of the potential for substantial discomfort as well as serious complications. The prevalence of polypharmacy in this population increases the risk for autoimmune drug reactions, and diagnosis should be undertaken with an awareness that polypharmacy in this population creates a greatly increased susceptibility to drug eruptions that can mimic other cutaneous disorders. Immunologic senescence in the elderly also sets the stage for potential reactivation of the Varicella zoster virus, in which initial dermatologic involvement expands into the major sensory ganglia. Known as shingles, this disorder can be excruciatingly painful with the potential to cause blindness if the optic nerve becomes involved. Dermatoses such as xerosis, pruritus, and eczema are also widespread in the elderly, create substantial suffering in those afflicted, and often prove recalcitrant to treatment. Individual susceptibility to specific types of contact dermatitis changes over the lifetime, and seborrheic dermatitis is substantially more prevalent in the elderly. It is not uncommon for older patients to have multiple impairments, with the potential for cognitive dysfunction as well as impaired vision, hearing, or mobility. In addition, they may not have adequate housing or nutrition, or the financial resources necessary for adequate compliance. Physicians must take into consideration the patient's physical ability to comply with the recommended therapy as well as socioeconomic factors that may impact on compliance. Simple topical regimens are preferable wherever possible in order to maximize compliance and, therefore, efficacy. Extra effort may be necessary to ensure that instructions are accurately followed and that ongoing compliance with the regimen prescribed is actually achieved. Management of dermatologic disorders in the elderly is often less than optimal, due to the fact that the special needs and limitations of this population are not adequately considered. Treatments should consider the intrinsic differences between younger and older patients that may impact on diagnosis and therapy choice. The aged patient is often afflicted with numerous co-morbidities that can influence the choice of therapy. Skin integrity in the elderly is compromised, and safety concerns are increased with the long-term use of any medication prescribed. In addition, the prevalence of polypharmacy in the aged population substantially increases the risk of cutaneous drug reactions, which can profoundly complicate accurate diagnosis of dermatologic disorders. The aged population also needs to be more closely monitored because of increased fragility of the skin and the physical limitations that may hinder compliance with prescribed regimens.

Magnetized electrode tip catheter

Abstract: Tachycardial arrhythmias are located and ablated by a combination of first and second catheters which are mutually attracted by magnetized regions at their distal ends. One of the catheters contains mapping electrodes and is initially used to ascertain the locus of the arrhythmia by conventional mapping. Once this is accomplished, the catheter is allowed to remain in position while the second catheter is inserted in such a manner that mutual magnetic attraction between the two occurs across cardiac tissue. One or the other of the two catheters also contains an ablation component at its tip, such that when the two catheter tips are held in position by virtue of their mutual magnetic attraction, ablation can be performed.