Distinct Sequences Research Articles

Subaru Hyper Suprime-Cam Survey of Cygnus OB2 Complex – I. Introduction, photometry, and source catalogue

ABSTRACT Low-mass star formation inside massive clusters is crucial to understand the effect of cluster environment on processes like circumstellar disc evolution, planet, and brown dwarf formation. The young massive association of Cygnus OB2, with a strong feedback from massive stars, is an ideal target to study the effect of extreme environmental conditions on its extensive low-mass population. We aim to perform deep multiwavelength studies to understand the role of stellar feedback on the IMF, brown dwarf fraction and circumstellar disc properties in the region. We introduce here, the deepest and widest optical photometry of 1.5○ diameter region centred at Cygnus OB2 in r2, i2, z, and Y-filters, using Subaru Hyper Suprime-Cam (HSC). This work presents the data reduction, source catalogue generation, data quality checks, and preliminary results about the pre-main sequence sources. We obtain 713 529 sources in total, with detection down to ∼28, 27, 25.5, and 24.5 mag in r2, i2, z, and Y-band, respectively, which is ∼3 – 5 mag deeper than the existing Pan-STARRS and GTC/OSIRIS photometry. We confirm the presence of a distinct pre-main sequence branch by statistical field subtraction of the central 18 arcmin region. We find the median age of the region as ∼5 ± 2 Myr with an average disc fraction of ∼9 per cent. At this age, combined with A $_V\, \sim$ 6 – 8 mag, we detect sources down to a mass range of ∼0.01–0.17 M⊙. The deep HSC catalogue will serve as the groundwork for further studies on this prominent active young cluster.

Importance of a turbulent river section below a giant waterfall for fish spawning: Indications from drift and dispersion patterns of early life stages

AbstractSeasonal drift patterns of fish eggs and larvae were analysed along the river section downstream the Iguaçu River Falls to the confluence with Paraná River, over three spawning seasons. This river section is situated in a narrow rocky canyon characterized by a steep slope, which leads to highly turbulent and fast flowing conditions in a series of rapids. Water transit time in this river stretch of 20 km was short (5–11 h), the flow‐velocity in rapids can reach values of more than 6 m s−1. Densities of drifting eggs and larvae varied between three spawning seasons, and differences of eggs were more pronounced compared to larvae. Eggs and larvae were observed all along the river section. A spatial, longitudinal distribution pattern of larvae was found, with higher numbers in the upper section. A distinct spatial sequence of different embryonic stages was observed, with the highest abundance of early stages. Larval densities were low in comparison to egg densities, and preflexion and flexion stages predominated. High abundance of buoyant eggs in drift indicates fish spawning in rapid and turbulent waters of the Iguaçu River, particularly downstream from the Iguaçu Falls. Rainfall and turbidity may be the main trigger for spawning. Spawned eggs drifted quickly towards the confluence, most are likely to hatch in the Paraná River, while larvae disperse to nursery habitats even in the river section below the falls. Thus, inshore zones along the whole stretch provide nursery habitats for larval development of fish species exhibiting different reproductive strategies.

Cut-and-project graphs and other complexes

The cut-and-project method may be applied to graphs and complexes, although there are technical difficulties, most notably “collisions,” i.e. when the images (under the projection) of two disjoint edges or cells intersect. Given a particular periodic structure, a particular projection space, an appropriate “window” in the orthogonal complement of that space, the induced substructure within the cartesian product of the window and the projection space is projected to the projection space to produce a “model structure.” We may use an index space of vectors from the orthogonal complement to move the window around and obtain a “model system” of model structures. We adapt the notion of “general position” to higher dimensions: the projection space is in “doubly general position” with respect to a graph or complex when the projection of that structure maps vertices of that structure injectively into the projection space and the edges or polytopes of that structure injectively so that their dimension is not reduced and disjoint edges and polytopes remain disjoint. We find that if the initial structure was a periodic graph, if the projection space and its complement are in general position with respect to the vertices and edges, and the window is also in general position, then the model system has uncountably many isomorphism classes - with distinct coordination sequences.

New Blue and Red Variable Stars in NGC 247

Abstract Images recorded with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South are combined with archival images from other facilities to search for variable stars in the southern half of the nearby disk galaxy NGC 247. Fifteen new periodic and nonperiodic variables are identified. These include three Cepheids with periods <25 days, four semiregular variables, one of which shows light variations similar to those of R CrB stars, five variables with intrinsic visible/red brightnesses and colors that are similar to those of luminous blue variables (LBVs), and three fainter blue variables, one of which may be a noneclipsing close binary system. The S Doradus instability strip defines the upper envelope of a distinct sequence of objects on the (i, g−i) color–magnitude diagram (CMD) of NGC 247. The frequency of variability of an amplitude ≥0.1 magnitude in the part of the CMD that contains LBVs over the seven-month period when the GMOS images were recorded is ∼0.2. The light curve of the B[e] supergiant J004702.18–204739.9, which is among the brightest stars in NGC 247, is also examined. Low-amplitude variations on day-to-day timescales are found, coupled with a systematic trend in mean brightness over a six-month time interval.

El diptongo/hiato como rasgo contrastivo: un estudio perceptual con hablantes de herencia de español

Abstract This study examines the perception of diphthongs and hiatuses in 11 heritage Spanish speakers and 6 Spanish-dominant bilingual speakers with an AXB discrimination task (Lukyanchenko, Anna & Kira Gor. 2011. Perceptual correlates of phonological representations in heritage speakers and L2 learners. In Nick Danis, Kate Mesh & Hyunsuk Sung (eds.), Proceedings of the 35th annual Boston University conference on language development, 414–426. Sommerville, MA: Cascadilla Press). In Spanish, diphthongs and hiatuses represent distinct vocalic sequences (Schwegler, Armin, Juergen Kempff & Ana Ameal-Guerra. 2010. Fonética y fonología españolas, 4th edn. Hoboken, NJ: Wiley). However, there are words in which the pronunciation of the vocalic sequence as either a diphthong or hiatus serves as a contrastive feature, as in the example of ley / leí (Face, Timothy L. & Scott M. Alvord. 2004. Lexical and acoustic factors in the perception of the Spanish diphthong vs. Hiatus contrast. Hispania 87(3). 553–564; Hualde, José I. & Mónica Prieto. 2002. On the diphthong/hiatus contrast in Spanish: Some experimental results. Linguistics 40(2). 217–234). Given that these features also exist in English, albeit in different forms, does L2 influence of English impact heritage Spanish listeners' perception of diphthongs and hiatuses in Spanish? Specifically, this study examines discrimination between the diphthong / hiatus as a contrasting feature with /a e o/ as the nucleic vowel in the diphthongs. Results indicate that there is not a significant difference in discrimination between heritage speakers and Spanish-dominant bilinguals. Additionally, the nucleic vowel in the diphthong tokens is a significant factor for the ability to discriminate diphthongs vs. hiatuses in heritage Spanish speakers. The findings of this study contribute to the corpus of phonetic studies focusing on heritage Spanish speakers and perception in their heritage language.

Stability and conformation of the dimeric HIV-1 genomic RNA 5′UTR

During HIV-1 assembly, the viral Gag polyprotein specifically selects the dimeric RNA genome for packaging into new virions. The 5′ untranslated region (5′UTR) of the dimeric genome may adopt a conformation that is optimal for recognition by Gag. Further conformational rearrangement of the 5′UTR, promoted by the nucleocapsid (NC) domain of Gag, is predicted during virus maturation. Two 5′UTR dimer conformations, the kissing dimer (KD) and the extended dimer (ED), have been identified in vitro, which differ in the extent of intermolecular basepairing. Whether 5′UTRs from different HIV-1 strains with distinct sequences have access to the same dimer conformations has not been determined. Here, we applied fluorescence cross-correlation spectroscopy and single-molecule Förster resonance energy transfer imaging to demonstrate that 5′UTRs from two different HIV-1 subtypes form (KDs) with divergent stabilities. We further show that both 5′UTRs convert to a stable dimer in the presence of the viral NC protein, adopting a conformation consistent with extensive intermolecular contacts. These results support a unified model in which the genomes of diverse HIV-1 strains adopt an ED conformation.

Toxin-Producing Klebsiella oxytoca in Healthy Infants: Commensal or Pathobiont?

Klebsiella oxytoca is a gastrointestinal pathobiont with the potential to produce the toxins tilivalline and tilimycin, which cause antibiotic-associated hemorrhagic colitis. Overgrowth of toxigenic K oxytoca has recently been implicated in necrotizing enterocolitis. K oxytoca colonizes 2-9% of healthy adults, however, there is no systematic data on colonization in healthy children. We investigated K oxytoca colonization and its toxigenic properties in healthy infants. We sampled stool of healthy infants and determined K oxytoca colonization using stool culture and PCR (pehX). Toxin in stool was measured with HPLC/high-resolution mass spectrometry. K oxytoca isolates were typed using multi-locus sequence typing (MLST) and K oxytoca toxin PCR (npsA/B). Cytotoxin production of isolates was analyzed by MTT assay. K oxytoca was detected in 30 of 61 infants (49%) using stool culture and in 45 of 61 (73%) using PCR (pehX). Toxin marker PCR (npsA/B) was positive in 66% of stool samples positive for K oxytoca PCR. Stool toxin levels were too low for quantitation but traces of tilivalline were detected. Contrarily, 49% of K oxytoca isolates demonstrated toxicity in the MTT assay. MLST revealed 36 distinct sequence types affiliated with all known K oxytoca sequence type clusters (A, B1 and B2). More than 70% of healthy infants were colonized with K oxytoca. Toxin quantities in stool of colonized healthy infants were below detection level, yet half of the isolates produced toxin in vitro demonstrating their pathobiont potential. The high occurrence of toxigenic K oxytoca in healthy infants has to be considered for future disease association studies.

Mixing dry and wet magmas in the lower crust of a continental arc: new petrological insights from the Bear Valley Intrusive Suite, southern Sierra Nevada, California

Exposures of arc crustal sections represent rare opportunities to directly evaluate lower crustal magmatic processes and their link to arc products in the middle and upper crust. Within the southernmost Sierra Nevada batholith, the Bear Valley Intrusive Suite (BVIS) exposes a contemporaneously constructed ~ 30 km thick intrusive suite, and thus is ideal for this type of examination. Here we present detailed petrography and mineral major and trace element data for the BVIS. The deepest exposed portion of the BVIS (8–9 kbars) is composed of heterogeneous mafic igneous intrusions of olivine metagabbro, olivine-hornblende orthopyroxenite, olivine-bearing hornblende norite, hornblende norite, hornblende gabbronorite, hornblendite and hornblende gabbro. Shallower crustal intrusions (3–7 kbars) are comparatively homogeneous and dominated by hypersthene-bearing and hypersthene-free tonalites. Using amphibole-plagioclase geothermometry, we show that the mafic lower crustal intrusions crystallized over a wide temperature range from 850 to 1070 °C, highlighting mafic igneous fractionation during isobaric cooling in the lower crust of the Sierran arc, while tonalitic liquids were emplaced at temperatures < 800 °C in the middle and upper crust. Calculated trace element melt compositions in equilibrium with amphibole in lower crustal gabbros are similar to measured tonalite bulk compositions and support the generation of tonalites through fractionation of the observed gabbros. Further, petrography and mineral chemistry suggest multiple distinct crystallization sequences recorded in the different types of gabbro, requiring the presence of coexisting parental melts with contrasting compositions and H2O contents. Using available experimental data, we develop a model by which mixing of variably fractionated dry and wet magmas with similar viscosities followed by crystallization-differentiation in the deep crust to explain the formation of uniform tonalitic melts at shallower crustal levels in the BVIS. This process also explains the unusual predominance of orthopyroxene in the BVIS, and the limited aluminum enrichment compared to experimental differentiation sequences of hydrous basalts. Considering the similar geochemical characteristics of intermediate and felsic igneous rocks from the Sierra Nevada batholith and the Cascades, mixing magmas of variable H2O contents in the lower crust represents a viable petrological process to produce SiO2-rich liquids that may be more common than previously recognized.

Emergence of Klebsiella pneumoniae ST307 Co-Producing CTX-M with SHV and KPC from Paediatric Patients at Shenzhen Children's Hospital, China.

AimWe investigated the clonal diversity of carbapenemase-producing Klebsiella pneumoniae isolates from the Shenzhen Children’s Hospital, China, and drew conclusions on the clinical and public health impact of these isolates as multidrug-resistant.MethodsFrom January 2014 to December 2018, a total number of 36 unique carbapenemase-producing clinical isolates of Klebsiella pneumoniae were collected out of 900 clinical isolates in paediatric patients from the Shenzhen Children’s Hospital, China. After carbapenemase production confirmation, antimicrobial susceptibility, resistance determinants and phylogenetic relationship were determined.ResultsThe isolates showed resistance to ceftazidime, ertapenem, ampicillin, cefazolin, ceftriaxone, cefotetan, ticarcillin, cefaclor, cefpodoxime, azlocillin, cefcapene, mezlocillin and ampicillin-sulbactam. Of the 36 Klebsiella pneumoniae carbapenemase genes coding isolates, blaNDM was the mostly detected 50% (n=18) followed by blaKPC and blaIMP 19% (n=7), blaVIM 17% (n=6), blaOXA-48-like 8% (n=3) and blaSME 5% (n=2), whereas extended-spectrum β-lactamase (blaSHV) was predominantly detected 92% (n=33) followed by blaCTX-M 53% (n=19) and blaCMY 28% (n=10). Pulsed-field gel electrophoresis typing showed eight different patterns, and twenty-five distinct sequences types were observed with ST307 being predominantly identified 11% (n=4), followed by ST2407 8% (n=3). Plasmid replicon typing results indicated that IncFIS, IncHI2, IncFIC and IncFIA plasmids carry blaCTX-M, blaSHV and blaNDM genes.ConclusionThis study reports on the occurrence and spread of carbapenemase and extended-spectrum β-lactamase encoding genes co-existence in sporadic Klebsiella pneumoniae ST307 in paediatric patients from the Shenzhen Children’s Hospital, China.

Molecular Evidence Suggests That Wolbachia pipientis (Rickettsiales: Anaplasmataceae) is Widely Associated With South American Sand Flies (Diptera: Psychodidae).

Wolbachia pipientis (Hertig) is an endosymbiotic microorganism widespread among arthropods and other invertebrate hosts, and employed in strategies to reduce the incidence of arthropod-borne diseases. Here, we used a PCR-based approach for 16S RNA and wsp genes to investigate the prevalence, geographical distribution, and strains of Wolbachia in sand flies (Diptera: Psychodidae: Phlebotominae), the main vectors of the causative agents of leishmaniasis, from three biomes in Brazil: Amazon, Cerrado, and Caatinga. We found that: 1) Wolbachia DNA is present in most (66.7%) of the sampled sand fly species, including vectors of Leishmania spp. (Ross, Trypanosomatida: Trypanosomatidae), 2) the prevalence of Wolbachia DNA varies among species and populations, 3) some strains of Wolbachia may have wider geographical and host range in South America, and 4) two phylogenetic distinct wsp sequences might represent two novel strains for Wolbachia in South America sand flies. Those findings increase the basic knowledge about Wolbachia in South American sand flies and might foster further researches on its use to reduce the transmission of sand fly-borne parasites.

Three Draft Genome Sequences of White Spot Syndrome Virus from India.

ABSTRACTWhite spot syndrome virus (WSSV) is a pathogen causing significant economic losses to shrimp aquaculture worldwide. Previously, five genome sequences of the virus from farmed shrimp (Penaeus vannamei and Penaeus monodon) in India were reported, all originating from farms located on the east coast of the country. Here, we report three new and distinct WSSV genome sequences, two from shrimp (P. vannamei) farmed on the west coast of India and the third from the east coast.

Identifying transcript 5'capped ends in Plasmodium falciparum.

BackgroundThe genome of the human malaria parasite Plasmodium falciparum is poorly annotated, in particular, the 5′ capped ends of its mRNA transcripts. New approaches are needed to fully catalog P. falciparum transcripts for understanding gene function and regulation in this organism.MethodsWe developed a transcriptomic method based on next-generation sequencing of complementary DNA (cDNA) enriched for full-length fragments using eIF4E, a 5′ cap-binding protein, and an unenriched control. DNA sequencing adapter was added after enrichment of full-length cDNA using two different ligation protocols. From the mapped sequence reads, enrichment scores were calculated for all transcribed nucleotides and used to calculate P-values of 5′ capped nucleotide enrichment. Sensitivity and accuracy were increased by combining P-values from replicate experiments. Data were obtained for P. falciparum ring, trophozoite and schizont stages of intra-erythrocytic development.Results5′ capped nucleotide signals were mapped to 17,961 non-overlapping P. falciparum genomic intervals. Analysis of the dominant 5′ capped nucleotide in these genomic intervals revealed the presence of two groups with distinctive epigenetic features and sequence patterns. A total of 4,512 transcripts were annotated as 5′ capped based on the correspondence of 5′ end with 5′ capped nucleotide annotated from full-length cDNA data.DiscussionThe presence of two groups of 5′ capped nucleotides suggests that alternative mechanisms may exist for producing 5′ capped transcript ends in P. falciparum. The 5′ capped transcripts that are antisense, outside of, or partially overlapping coding regions may be important regulators of gene function in P. falciparum.

Motilin Comparative Study: Structure, Distribution, Receptors, and Gastrointestinal Motility.

Motilin, produced in endocrine cells in the mucosa of the upper intestine, is an important regulator of gastrointestinal (GI) motility and mediates the phase III of interdigestive migrating motor complex (MMC) in the stomach of humans, dogs and house musk shrews through the specific motilin receptor (MLN-R). Motilin-induced MMC contributes to the maintenance of normal GI functions and transmits a hunger signal from the stomach to the brain. Motilin has been identified in various mammals, but the physiological roles of motilin in regulating GI motility in these mammals are well not understood due to inconsistencies between studies conducted on different species using a range of experimental conditions. Motilin orthologs have been identified in non-mammalian vertebrates, and the sequence of avian motilin is relatively close to that of mammals, but reptile, amphibian and fish motilins show distinctive different sequences. The MLN-R has also been identified in mammals and non-mammalian vertebrates, and can be divided into two main groups: mammal/bird/reptile/amphibian clade and fish clade. Almost 50 years have passed since discovery of motilin, here we reviewed the structure, distribution, receptor and the GI motility regulatory function of motilin in vertebrates from fish to mammals.

Longitudinal Secretion of Paramyxovirus RNA in the Urine of Straw-Coloured Fruit Bats (Eidolon helvum).

The straw-coloured fruit bat (Eidolon helvum) is widespread in sub-Saharan Africa and is widely hunted for bushmeat. It is known to harbour a range of paramyxoviruses, including rubuloviruses and henipaviruses, but the zoonotic potential of these is unknown. We previously found a diversity of paramyxoviruses within a small, captive colony of E. helvum after it had been closed to contact with other bats for 5 years. In this study, we used under-roost urine collection to further investigate the paramyxovirus diversity and ecology in this colony, which had been closed to the outside for 10 years at the time of sampling. By sampling urine weekly throughout an entire year, we investigated possible seasonal patterns of shedding of virus or viral RNA. Using a generic paramyxovirus L-gene PCR, we detected eight distinct paramyxovirus RNA sequences. Six distinct sequences were detected using a Henipavirus-specific PCR that targeted a different region of the L-gene. Sequence detection had a bi-annual pattern, with the greatest peak in July, although different RNA sequences appeared to have different shedding patterns. No significant associations were detected between sequence detection and birthing season, environmental temperature or humidity, and no signs of illness were detected in any of the bats in the colony during the period of sample collection.

Phylogenetically Distinct Near-Complete Genome Sequences of Porcine Reproductive and Respiratory Syndrome Virus Type 2 Variants from Four Distinct Disease Outbreaks at U.S. Swine Farms over the Past 6 Years.

ABSTRACTPorcine reproductive and respiratory syndrome virus (PRRSV) continues to mutate, causing disruptive PRRS outbreaks in farms that lead to reproductive failure and respiratory disease-associated mortality. We present four new PRRSV type 2 variants in the United States belonging to four distinct orf5 sublineages within lineage 1.

Identifying the Phenotypic and Temporal Heterogeneity of Knee Osteoarthritis: Data From the Osteoarthritis Initiative.

Objective: Previous studies discussing phenotypic and temporal heterogeneity of knee osteoarthritis (KOA) separately have fatal limitations that either clustering patients with similar severity or assuming all knees have a single common progression pattern, which are unreliable. This study tried to uncover more reliable information on phenotypic and temporal heterogeneity of KOA.Design: Data were from Osteoarthritis Initiative database. Six hundred and seventy-eight unilateral knees that have greater Kellgren and Lawrence (KL) grade than the contralateral knees at baseline and in all follow-up 48 months were included. Measurements of biomarkers at baseline were chosen. Subtype and Stage Inference model (SuStaIn) was applied as a subtype-progression model to identify subtypes, subtype biomarker progress sequences and stages of KOA.Results: This study identified three subtypes which account for 15, 61, and 24% of knees, respectively. Each subtype has distinct subtype biomarker progress sequence. For knees with KL grade 0/1, 2, 3, and 4, they have different distributions on stage and 26, 53, 89, and 95% of them are strongly assigned to subtypes. When assessing whether a knee has KL (grade ≥ 2), subtypes and stages from subtypes-progression model (SuStaIn) are significantly better fitting than those from subtypes-only (mixture of Gaussians) (likelihood ratio = 105.59, p = 2.2 × 10−16) or stages-only (SuStaIn where setting c = 1) (likelihood ratio = 58.04, p = 2.57 × 10−14) model. Stages in subtypes-progression model has greater β than stages-only model. Subtypes from subtypes-progression model have no statistical significance.Conclusions: For subtypes-progression model, stages contain more complete temporal information and subtypes are closer to real OA subtypes.

Whole Genome Sequencing of Pediatric Klebsiella pneumoniae Strains Reveals Important Insights Into Their Virulence-Associated Traits.

Klebsiella pneumoniae is recognized as a common cause of nosocomial infections and outbreaks causing pneumonia, septicemia, and urinary tract infections. This opportunistic bacterium shows an increasing acquisition of antibiotic-resistance genes, which complicates treatment of infections. Hence, fast reliable strain typing methods are paramount for the study of this opportunistic pathogen’s multi-drug resistance genetic profiles. In this study, thirty-eight strains of K. pneumoniae isolated from the blood of pediatric patients were characterized by whole-genome sequencing and genomic clustering methods. Genes encoding β-lactamase were found in all the bacterial isolates, among which the blaSHV variant was the most prevalent (53%). Moreover, genes encoding virulence factors such as fimbriae, capsule, outer membrane proteins, T4SS and siderophores were investigated. Additionally, a multi-locus sequence typing (MLST) analysis revealed 24 distinct sequence types identified within the isolates, among which the most frequently represented were ST76 (16%) and ST70 (11%). Based on LPS structure, serotypes O1 and O3 were the most prevalent, accounting for approximately 63% of all infections. The virulence capsular types K10, K136, and K2 were present in 16, 13, and 8% of the isolates, respectively. Phylogenomic analysis based on virtual genome fingerprints correlated with the MLST data. The phylogenomic reconstruction also denoted association between strains with a higher abundance of virulence genes and virulent serotypes compared to strains that do not possess these traits. This study highlights the value of whole-genomic sequencing in the surveillance of virulence attributes among clinical K. pneumoniae strains.

Characterization of Tigecycline Resistance Among Tigecycline Non-susceptible Klebsiella pneumoniae Isolates From Humans, Food-Producing Animals, and in vitro Selection Assay.

Emergence of extensively drug-resistant isolates of Klebsiella pneumoniae has prompted increased reliance on the last-resort antibiotics such as tigecycline (TGC) for treating infections caused by these pathogens. Consumption of human antibiotics in the food production industry has been found to contribute to the current antibiotic resistance crisis. In the current study, we aimed to investigate the mechanisms of TGC resistance among 18 TGC-non-susceptible (resistant or intermediate) K. pneumoniae (TGC-NSKP) isolates obtained from human (n = 5), food animals (n = 7), and in vitro selection experiment (n = 6). Isolates were genotyped by multilocus sequence typing (MLST). ramR, acrR, rpsJ, tetA, and mgrB (for colistin resistance) genes were sequenced. The presence of tetX, tetX1, and carbapenemase genes was examined by PCR. Susceptibility to different classes of antibiotics was evaluated by disc diffusion and broth macrodilution methods. The expression level of acrB was quantified by RT-qPCR assay. The 12 TGC-NSKP isolates [minimum inhibitory concentrations (MICs) = 4–32 mg/l] belonged to 10 distinct sequence types including ST37 (n = 2), ST11, ST15, ST45, ST1326 (animal isolates); ST147 (n = 2, human and animal isolates); and ST16, ST377, ST893, and ST2935 (human isolates). Co-resistance to TGC and colistin was identified among 57 and 40% of animal and human isolates, respectively. All human TGC-NSKP isolates carried carbapenemase genes (blaOXA–48, blaNDM–1, and blaNDM–5). tetX/X1 genes were not detected in any isolates. About 83% of TGC-NSKP isolates (n = 15) carried ramR and/or acrR alterations including missense/nonsense mutations (A19V, L44Q, I141T, G180D, A28T, R114L, T119S, Y59stop, and Q122stop), insertions (positions +205 and +343), or deletions (position +205) for ramR, and R90G substitution or frameshift mutations for acrR. In one isolate ramR amplicon was not detected using all primers used in this study. Among seven colistin-resistant isolates, five harbored inactivated/mutated MgrB due to premature termination by nonsense mutations, insertion of IS elements, and frameshift mutations. All isolates revealed wild-type RpsJ and TetA (if present). Increased expression of acrB gene was detected among all resistant isolates, with the in vitro selected mutants showing the highest values. A combination of RamR and AcrR alterations was involved in TGC non-susceptibility in the majority of studied isolates.

Microstructure tailoring of Al-containing compositionally complex alloys by controlling the sequence of precipitation and ordering

Refractory metal-based, Al-containing compositionally complex alloys (RCCA) are promising candidates for high-temperature structural applications. To shed light on the complex phase transitions, thermodynamic calculations were performed to select two representative alloys with different sequences in phase transitions. Samples of these compositions were synthesized by arc melting of pure elements followed by a homogenization treatment to experimentally verify the room temperature microstructure and assess the phase transitions. Differential scanning calorimetry (DSC), scanning (SEM) and transmission electron microscopy (TEM) studies after the homogenization and quenching revealed multiple distinct sequences of transitions: (i) 82(TaMoTi)-8Cr-10Al (in at.%) exhibits a solid-state phase separation concurrent with ordering of the precipitates. This results in a disordered matrix with ordered precipitates. Thermal analysis indicates that while cooling from the high-temperature A2 phase, the phase separation and ordering are spread out over a large temperature range (approx. 750 – 1250°C), with a peak at 1055°C. (ii) In the 77(TaMoTi)-8Cr-15Al alloy, a continuous phase transition at 1155°C leads to a single-phase B2 matrix with planar faults. At slightly lower temperatures (approx. 1096°C), phase separation occurs resulting in a B2 matrix with segregation at planar faults and A2 precipitates. In both investigated compositions, the A2 phase is enriched in Ta and Mo. Conversely, the B2 phase is enriched in Al and Ti, while Cr is uniformly distributed in the phases.

Transmission Dynamics of Severe Acute Respiratory Syndrome Coronavirus 2 in High-Density Settings, Minnesota, USA, March-June 2020.

Coronavirus disease has disproportionately affected persons in congregate settings and high-density workplaces. To determine more about the transmission patterns of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in these settings, we performed whole-genome sequencing and phylogenetic analysis on 319 (14.4%) samples from 2,222 SARS-CoV-2–positive persons associated with 8 outbreaks in Minnesota, USA, during March–June 2020. Sequencing indicated that virus spread in 3 long-term care facilities and 2 correctional facilities was associated with a single genetic sequence and that in a fourth long-term care facility, outbreak cases were associated with 2 distinct sequences. In contrast, cases associated with outbreaks in 2 meat-processing plants were associated with multiple SARS-CoV-2 sequences. These results suggest that a single introduction of SARS-CoV-2 into a facility can result in a widespread outbreak. Early identification and cohorting (segregating) of virus-positive persons in these settings, along with continued vigilance with infection prevention and control measures, is imperative.