Differential forms in positive characteristic avoiding resolution of singularities

This paper studies several notions of sheaves of differential forms that are better behaved on singular varieties than K\"ahler differentials. Our main focus lies on varieties that are defined over fields of positive characteristic. We identify two promising notions: the sheafification with respect to the cdh-topology, and right Kan extension from the subcategory of smooth varieties to the category of all varieties. Our main results are that both are cdh-sheaves and agree with K\"ahler differentials on smooth varieties. They agree on all varieties under weak resolution of singularities. A number of examples highlight the difficulties that arise with torsion forms and with alternative candiates.Comment: The new version contains a considerable improvement on the earlier version. Following the remark of a referee, we are now able to show cdh-descent for differential forms on smooth varietie

Differential forms in positive characteristic II: cdh-descent via functorial Riemann-Zariski spaces

This paper continues our study of the sheaf associated to K\"ahler differentials in the cdh-topology and its cousins, in positive characteristic, without assuming resolution of singularities. The picture for the sheaves themselves is now fairly complete. We give a calculation $\mathcal{O}_{cdh}(X) \cong \mathcal{O}(X^{sn})$ in terms of the seminormalisation. We observe that the category of representable cdh-sheaves is equivalent to the category of seminormal varieties. We conclude by proposing some possible connections to Berkovich spaces, and $F$-singularities in the last section. The tools developed for the case of differential forms also apply in other contexts and should be of independent interest.Comment: 37 page

Synthesis and characterisation of isomeric cycloaurated complexes derived from the iminophosphorane Ph₃P=NC(O)Ph

Using different organomercury substrates, two isomeric cycloaurated complexes derived from the stabilised iminophosphorane Ph₃P NC(O)Ph were prepared. Reaction of Ph₃P NC(O)Ph with PhCH₂Mn(CO)₅ gave the manganated precursor (CO)₄Mn(2-C₆H₄C(O)N PPh₃), metallated on the C(O)Ph substituent, which yielded the organomercury complex ClHg(2-C₆H₄C(O)N PPh₃) by reaction with HgCl₂ in methanol. Transmetallation of the mercurated derivative with Me₄N[AuCl₄] gave the cycloaurated iminophosphorane AuCl₂(2-C₆H₄C(O)N PPh₃) with an exo PPh₃ substituent. The endo isomer AuCl₂(2-C₆H₄Ph₂P NC(O)Ph) [aurated on a PPh₃ ring] was obtained by an independent reaction sequence, involving reaction of the diarylmercury precursor Hg(2-C₆H₄P( NC(O)Ph)Ph₂)₂ [prepared from the known compound Hg(2-C₆H₄PPh₂)₂ and PhC(O)N₃] with Me₄N[AuCl₄]. Both of the isomeric iminophosphorane derivatives were structurally characterised, together with the precursors (2-HgClC₆H₄)C(O)N PPh₃ and (CO)₄Mn(2-C₆H₄C(O)N PPh₃). The utility of ³¹P NMR spectroscopy in monitoring reaction chemistry in this system is described

Emerging executive functioning and motor development in infants at high and low risk for autism spectrum disorder

Existing evidence suggests executive functioning (EF) deficits may be present in children with autism spectrum disorder (ASD) by 3 years of age. It is less clear when, prior to 3 years, EF deficits may emerge and how EF unfold over time. The contribution of motor skill difficulties to poorer EF in children with ASD has not been systematically studied. We investigated the developmental trajectory of EF in infants at high and low familial risk for ASD (HR and LR) and the potential associations between motor skills, diagnostic group, and EF performance. Participants included 186 HR and 76 LR infants. EF (A-not-B), motor skills (Fine and Gross Motor), and cognitive ability were directly assessed at 12 months and 24 months of age. Participants were directly evaluated for ASD at 24 months using DSM-IV-TR criteria and categorized as HR-ASD, HR-Negative, and LR-Negative. HR-ASD and HR-Negative siblings demonstrated less improvement in EF over time compared to the LR-Negative group. Motor skills were associated with group and EF performance at 12 months. No group differences were found at 12 months, but at 24 months, the HR-ASD and HR-Negative groups performed worse than the LR-Negative group overall after controlling for visual reception and maternal education. On reversal trials, the HR-ASD group performed worse than the LR-Negative group. Motor skills were associated with group and EF performance on reversal trials at 24 months. Findings suggest that HR siblings demonstrate altered EF development and that motor skills may play an important role in this process

STRAD Pseudokinases Regulate Axogenesis and LKB1 Stability

BACKGROUND: Neuronal polarization is an essential step of morphogenesis and connectivity in the developing brain. The serine/threonine kinase LKB1 is a key regulator of cell polarity, metabolism, tumorigenesis, and is required for axon formation. It is allosterically regulated by two related and evolutionarily conserved pseudokinases, STe20-Related ADapters (STRADs) α and β. The roles of STRADα and STRADβ in the developing nervous system are not fully defined, nor is it known whether they serve distinct functions. RESULTS: We find that STRADα is highly spliced and appears to be the primal STRAD paralog. We report that each STRAD is sufficient for axogenesis and promoting cell survival in the developing cortex. We also reveal a reciprocal protein-stabilizing relationship in vivo between LKB1 and STRADα, whereby STRADα specifically maintains LKB1 protein levels via cytoplasmic compartmentalization. CONCLUSIONS: We demonstrate a novel role for STRADβ in axogenesis and also show for the first time in vivo that STRADα, but not STRADβ, is responsible for LKB1 protein stability

Risk of exposure to Coxiella burnetii from ruminant livestock exhibited at Iowa agricultural fairs

Coxiella burnetii is a zoonotic pathogen typically associated with clinical and asymptomatic infection in ruminant livestock. A re‐emerging pathogen of significant public health importance, C. burnetii has caused recent epidemics in the U.S. and Europe and public livestock exhibitions are increasingly scrutinized as a potential source of C. burnetii exposure. Although C. burnetii prevalence data among North American domestic ruminants is extremely limited, contemporary studies suggest that this pathogen is both geographically widespread and highly prevalent on a herd basis, especially in dairy cattle and goat populations. We utilized a real‐time PCR assay to detect Coxiella burnetii fecal shedding by clinically normal, non‐periparturient beef cattle, meat goats, and sheep exhibited at Iowa agricultural fairs. Individual fecal samples were collected from beef cattle, meat goats, and sheep exhibited at twelve Iowa county fairs during the summer of 2009. The sample pool was blocked by species and fair, ten samples from each block were randomly selected for the diagnostic assay; this test pool is considered sufficient to identify with 95% confidence a shedding animal in a population prevalence of 2.85% (cattle and sheep) and 6.25% (goats). Detection of Coxiella burnetii DNA was determined through use of a real time PCR assay validated for use in bovine, ovine, and caprine feces; threshold of detection is one DNA copy per PCR (sensitivity 95.8%, specificity 100%). All tested samples were negative for Coxiella burnetii DNA. We conclude that non‐dairy, non‐periparturient ruminants exhibited at Iowa fairs are unlikely to shed Coxiella burnetii in their feces and that this population should not be considered to be a significant exposure risk to other livestock or fair attendees

Finessing Incivility: The professional socialisation experiences of student nurses' first clinical placement, a grounded theory.

Background Clinical practice is where student nurses are socialised into a professional role and acquire the distinct behaviour, attitudes and values of the nursing profession. Getting it right at the outset can maximise the development of a professional identity and the transmission of robust value systems. Objectives To explore the impact of the first clinical placement on the professional socialisation of adult undergraduate student nurses in the United Kingdom. Design Data of a longitudinal qualitative nature were collected and analysed using grounded theory. Settings First year student nurses in hospital ward placements comprising a rural District General Hospital and a large inner city Hospital kept daily unstructured diaries for six weeks. Participants A total of 26 undergraduate adult student nurses were purposefully sampled between 2008 and 2010 before undertaking their initial clinical placement. Methods Data collection and analysis used grounded theory and the key question asked of the diarists ‘tell me what it is like to be a first year nurse on a first placement’ was theoretically adjusted during constant comparison and as the theory emerged. Ethical approval and consent was obtained. Results The theory of finessing incivility comprises a conceptual framework depicting how student nurses deal with professional incivility during their initial clinical placement and sustain a student identity. Being disillusioned with their role as worker rather than learner yields a sense of ‘status dislocation’. Despite needing professional benevolence, they remain altruistic and seek recompense from significant others to negotiate for learning opportunities and relocate their student status. Conclusions Despite the stressful transition into clinical practice rather than ‘fit in’, the student nurses want to belong as learners. His or her own resilience to learn nursing and be a professional student maintains their resolve, their altruism and strengthens their existing values to be benevolent towards an indifferent profession. This behaviour ultimately mirrors the social nature of the practice community