Evidence suggests that SARS-CoV-2, as well as other coronaviruses, can be dispersed and potentially transmitted by aerosols directly or via ventilation systems. We therefore investigated ventilation ...openings in one COVID-19 ward and central ducts that expel indoor air from three COVID-19 wards at Uppsala University Hospital, Sweden, during April and May 2020. Swab samples were taken from individual ceiling ventilation openings and surfaces in central ducts. Samples were subsequently subjected to rRT-PCR targeting the N and E genes of SARS-CoV-2. Central ventilation HEPA filters, located several stories above the wards, were removed and portions analyzed in the same manner. In two subsequent samplings, SARS-CoV-2 N and E genes were detected in seven and four out of 19 room vents, respectively. Central ventilation HEPA exhaust filters from the ward were found positive for both genes in three samples. Corresponding filters from two other, adjacent COVID-19 wards were also found positive. Infective ability of the samples was assessed by inoculation of susceptible cell cultures but could not be determined in these experiments. Detection of SARS-CoV-2 in central ventilation systems, distant from patient areas, indicate that virus can be transported long distances and that droplet transmission alone cannot reasonably explain this, especially considering the relatively low air change rates in these wards. Airborne transmission of SARS-CoV-2 must be taken into consideration for preventive measures.
Noroviruses are the most common etiological agent of acute gastroenteritis worldwide. Despite their high infectivity, a subpopulation of individuals is resistant to infection and disease. This ...susceptibility is norovirus genotype-dependent and is largely mediated by the presence or absence of human histo-blood group antigens (HBGAs) on gut epithelial surfaces. The synthesis of these HBGAs is mediated by fucosyl- and glycosyltransferases under the genetic control of the
(secretor),
(Lewis) and
genes. The so-called non-secretors, having an inactivated FUT2 enzyme, do not express blood group antigens and are resistant to several norovirus genotypes, including the predominant GII.4. Significant genotypic and phenotypic diversity of HBGA expression exists between different human populations. Here, we review previous in vivo studies on genetic susceptibility to norovirus infection. These are discussed in relation to population susceptibility, vaccines, norovirus epidemiology and the impact on public health.
The state of the art in semantic segmentation is steadily increasing in performance, resulting in more precise and reliable segmentations in many different applications. However, progress is limited ...by the cost of generating labels for training, which sometimes requires hours of manual labor for a single image. Because of this, semi-supervised methods have been applied to this task, with varying degrees of success. A key challenge is that common augmentations used in semi-supervised classification are less effective for semantic segmentation. We propose a novel data augmentation mechanism called ClassMix, which generates augmentations by mixing unlabelled samples, by leveraging on the network's predictions for respecting object boundaries. We evaluate this augmentation technique on two common semi-supervised semantic segmentation benchmarks, showing that it attains state-of-the-art results. Lastly, we also provide extensive ablation studies comparing different design decisions and training regimes.
Semantic segmentation models based on convolutional neural networks have recently displayed remarkable performance for a multitude of applications. However, these models typically do not generalize ...well when applied on new domains, especially when going from synthetic to real data. In this paper we address the problem of unsupervised do-main adaptation (UDA), which attempts to train on labelled data from one domain (source domain), and simultaneously learn from unlabelled data in the domain of interest (target domain). Existing methods have seen success by training on pseudo-labels for these unlabelled images. Multiple techniques have been proposed to mitigate low-quality pseudo-labels arising from the domain shift, with varying degrees of success. We propose DACS: Domain Adaptation via Cross-domain mixed Sampling, which mixes images from the two domains along with the corresponding labels and pseudo-labels. These mixed samples are then trained on, in addition to the labelled data itself. We demonstrate the effectiveness of our solution by achieving state-of-the-art results for GTA5 to Cityscapes, a common synthetic-to-real semantic segmentation benchmark for UDA.
Despite significant reduction of rotavirus (RV) infections following implementation of RotaTeq vaccination in Nicaragua, a large burden of patients with diarrhea persists.
We conducted a community- ...and hospital-based study of the burden of RV, norovirus (NV) and sapovirus (SV) infections as cause of sporadic acute gastroenteritis (GE) among 330 children ≤ 5 years of age between September 2009 and October 2010 in two major cities of Nicaragua with a RotaTeq coverage rate of 95%.
We found that NV, SV and RV infections altogether accounted for 45% of cases of GE. Notably, NV was found in 24% (79/330) of the children, followed by SV (17%, 57/330) and RV (8%, 25/330). The detection rate in the hospital setting was 27%, 15% and 14% for NV, SV and RV respectively, whereas in the community setting the detection rate of RV was < 1%. Among each of the investigated viruses one particular genogroup or genotype was dominant; GII.4 (82%) for NV, GI (46%) for SV and G1P8 (64%) in RV. These variants were also found in higher proportions in the hospital setting compared to the community setting. The GII.4.2006 Minerva strain circulating globally since 2006 was the most common among genotyped NV in this study, with the GII.4-2010 New Orleans emerging in 2010.
This study shows that NV has become the leading viral cause of gastroenteritis at hospital and community settings in Nicaragua after implementation of RV vaccination.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The use of language is central to the constituting and expressing of academic understanding. The theme of this article is set against the background of previous and ongoing phenomenographic research, ...with a theoretical approach presented as an alternative to main cognitive and socio-cultural approaches. One main characteristic of this researchis a focus on the relation between the learner as an agent and the external situation the learner relates to, especially the subject matter, and the knowledge involved in this relation. It is suggested that to fullyunderstand the constituting and expressing of academic understanding one has to consider the immediate personal and situational context, and to see the learner as an agent mediating the relation to, and thesignificance of, broader cognitive and socio-cultural contexts. This means considering the personal context in a more complete way than is done in either cognitive or socio-cultural orientations. Three cases, selected from previous interview research, are presented to demonstrate the importance of the agency of the learners, using a contextual phenomenographic approach which proved useful in discerning and clarifying the personal, situational, cognitive and socio-cultural contexts within which academic understanding develops.
Background. The live oral rotavirus (RV) vaccines have shown a reduced efficacy in Africa. Recent in vitro studies have shown binding of the RV surface protein (VP4) to histo–blood group antigens ...(HBGAs) in an RV genotype–dependent manner, suggesting them to be putative receptors for RV. The diversity of HBGA phenotypes in different ethnic populations, combined with prevalence/absence of specific RV genotypes, led us to hypothesize whether the genetic variations in HBGAs in a population limit susceptibility to certain RV genotypes, plausibly leading to reduced vaccine efficacy. Methods. Association between HBGAs status and susceptibility to RV P genotypes was investigated in children in Burkina Faso and Nicaragua. In total, 242 children with diarrhea in Burkina Faso and Nicaragua were investigated, 93 of whom were RV positive. Results. In Burkina Faso, the P8 RV strains (n = 27) infected only Lewis- and secretor-positive children (27/27; P < .0001), but no Lewis-negative children. In contrast, the P6 strains (n = 27) infected predominantly Lewis-negative children (n = 18; P < .0001) but also Lewis-positive children, irrespective of their secretor status. The results from Nicaragua confirmed that all P8-infected children (n = 22) were secretor Lewis positive. Conclusions. As VP4 of genotype P8 is a component of current RV vaccines, our finding that Lewis-negative children are resistant to P8 strains provides a plausible explanation for the reduced vaccine efficacy in populations with a high percentage of Lewis-negative individuals, such as in Africa. Furthermore, our findings provide a plausible explanation as to why P6 RV strains are more common in Africa.
5G communication systems operating above 24 GHz have promising properties for user localization and environment mapping. Existing studies have either relied on simplified abstract models of the ...signal propagation and the measurements, or are based on direct positioning approaches, which directly map the received waveform to a position. In this study, we consider an intermediate approach, which consists of four phases-downlink data transmission, multi-dimensional channel estimation, channel parameter clustering, and simultaneous localization and mapping (SLAM) based on a novel likelihood function. This approach can decompose the problem into simpler steps, thus leading to lower complexity. At the same time, by considering an end-to-end processing chain, we are accounting for a wide variety of practical impairments. Simulation results demonstrate the efficacy of the proposed approach.
Innate resistance to viral infections can be attributed to mutations in genes involved in the immune response, or to the receptor/ligand. A remarkable example of the latter is the recently described ...Mendelian trait resistance to clinically important and globally predominating genotypes of rotavirus, the most common agent of severe dehydrating gastroenteritis in children worldwide. This resistance appears to be rotavirus genotype-dependent and is mainly mediated by histo-blood group antigens (HBGAs), which function as a receptor or attachment factors on gut epithelial surfaces. HBGA synthesis is mediated by fucosyltransferases and glycosyltransferases under the genetic control of the
(secretor),
(Lewis), and
genes on chromosome 19. Significant genotypic and phenotypic diversity of HBGA expression exists between different human populations. This genetic diversity has an effect on genotype-specific susceptibility, molecular epidemiology, and vaccine take. Here, we will discuss studies on genetic susceptibility to rotavirus infection and place them in the context of population susceptibility, rotavirus epidemiology, vaccine take, and public health impact.
While rotavirus diarrhea has been considered to occur only due to intrinsic intestinal effects within the enteric nervous system, we provide evidence for central nervous system control underlying the ...clinical symptomology. Our data visualize infection by large-scale three-dimensional (3D) volumetric tissue imaging of a mouse model and demonstrate that rotavirus infection disrupts the homeostasis of the autonomous system by downregulating tyrosine hydroxylase in the noradrenergic sympathetic nervous system in ileum, concomitant with increased intestinal transit. Interestingly, the nervous response was found to occur before the onset of clinical symptoms. In adult infected animals, we found increased pS6 immunoreactivity in the area postrema of the brain stem and decreased phosphorylated STAT5-immunoreactive neurons in the bed nucleus of the stria terminalis, which has been associated with autonomic control, including stress response. Our observations contribute to knowledge of how rotavirus infection induces gut-nerve-brain interaction early in the disease. IMPORTANCE Previous studies have investigated the mechanisms of rotavirus diarrhea mainly by focusing on intrinsic intestinal signaling. Although these observations are compelling and have provided important mechanistic information on rotavirus diarrhea, no information is available on how the gut communicates with the central nervous system (CNS) during rotavirus infection or on how this communication initiates sickness symptoms. We show that rotavirus infection presymptomatically disrupts the autonomic balance by downregulating the noradrenergic sympathetic nervous system in ileum, concomitant with increased intestinal transit and altered CNS activity, particularly in regions associated with autonomic control and stress response. Altogether, these observations reveal that the rotavirus-infected gut communicates with the CNS before the onset of diarrhea, a surprising observation that brings a new understanding of how rotavirus gives rise to sickness symptoms.
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