Invariants of 2+1 Quantum Gravity

In [1,2] we established and discussed the algebra of observables for 2+1 gravity at both the classical and quantum level. Here our treatment broadens and extends previous results to any genus $g$ with a systematic discussion of the centre of the algebra. The reduction of the number of independent observables to $6g-6 (g > 1)$ is treated in detail with a precise classification for $g = 1$ and $g = 2$.Comment: 10 pages, plain TEX, no figures, DFTT 46/9

Management Culture and Surveillance

As the modern workplace increasingly adopts technology, that technology is being used to surveil workers in ways that can be highly invasive. Ostensibly, management uses surveillance to assess workers’ productivity, but it uses the same systems to, for example, map their interpersonal relationships, study their conversations, collect data on their health, track where they travel on and off the job, as well as monitor and manipulate their emotional responses. Many of these overreaches are justified in the name of enterprise control. That justification should worry us. This Article aims to make us think about how surveillance is being used as a management tool. It raises broader questions about how management may use its tools if unchecked, especially given what we know about the origins and development of modern management from its roots in the slave plantations of the U.S. South and the West Indies. Given this history, the Article argues for a new framework of analysis based on requiring better justifications for why managers need each piece of data that they collect on workers. “Everything is tracked, recorded and analyzed, via vertical reporting systems, double-entry record-keeping and precise quantification. Data seems to hold sway over every operation. It feels like a cutting-edge approach to management, but many of these techniques that we now take for granted were developed by and for large plantations” to control slaves. —Professor Matthew Desmond, describing the roots of modern management systems

The mass insertion approximation without squark degeneracy

We study the applicability of the mass insertion approximation (MIA) for calculations of neutral meson mixing when squark masses are not degenerate and, in particular, in models of alignment. We show that the MIA can give results that are much better than an order of magnitude estimate as long as the masses are not strongly hierarchical. We argue that, in an effective two-squark framework, m_q=(m_1+m_2)/2 is the best choice for the MIA expansion point, rather than, for example, m_q^2=(m_1^2+m_2^2)/2.Comment: 7 pages, revtex

Einstein, incompleteness, and the epistemic view of quantum states

Does the quantum state represent reality or our knowledge of reality? In making this distinction precise, we are led to a novel classification of hidden variable models of quantum theory. Indeed, representatives of each class can be found among existing constructions for two-dimensional Hilbert spaces. Our approach also provides a fruitful new perspective on arguments for the nonlocality and incompleteness of quantum theory. Specifically, we show that for models wherein the quantum state has the status of something real, the failure of locality can be established through an argument considerably more straightforward than Bell's theorem. The historical significance of this result becomes evident when one recognizes that the same reasoning is present in Einstein's preferred argument for incompleteness, which dates back to 1935. This fact suggests that Einstein was seeking not just any completion of quantum theory, but one wherein quantum states are solely representative of our knowledge. Our hypothesis is supported by an analysis of Einstein's attempts to clarify his views on quantum theory and the circumstance of his otherwise puzzling abandonment of an even simpler argument for incompleteness from 1927.Comment: 18 pages, 8 figures, 1 recipe for cupcakes; comments welcom

Interpretation of long-range interatomic force

Recent direct mechanical measurements of atomic force microscopy showed that the force between the silicon tip and the silicon sample is long range in the attractive region and its magnitude at maximum is relatively smaller. These features disagree with previous theoretical predictions based on the ab initio calculations. We investigated the nature of forces between a silicon tip and the silicon (111)-(2×1) surface by performing first-principles pseudopotential and classical molecular dynamics calculations and by calculating the van der Waals interaction. The first two methods give forces that are short range in nature. Fair agreement between the experiment and theory is obtained when the van der Waals interaction is included. The effect of the tip induced deformation is analyzed. © 1999 The American Physical Society

Quantum measurement in a family of hidden-variable theories

The measurement process for hidden-configuration formulations of quantum mechanics is analysed. It is shown how a satisfactory description of quantum measurement can be given in this framework. The unified treatment of hidden-configuration theories, including Bohmian mechanics and Nelson's stochastic mechanics, helps in understanding the true reasons why the problem of quantum measurement can succesfully be solved within such theories.Comment: 16 pages, LaTeX; all special macros are included in the file; a figure is there, but it is processed by LaTe

Specific pathway abundances in the neonatal calf faecal microbiome are associated with susceptibility to Cryptosporidium parvum infection: a metagenomic analysis.

Cryptosporidium parvum is the main cause of calf scour worldwide. With limited therapeutic options and research compared to other Apicomplexa, it is important to understand the parasites' biology and interactions with the host and microbiome in order to develop novel strategies against this infection. The age-dependent nature of symptomatic cryptosporidiosis suggests a link to the undeveloped immune response, the immature intestinal epithelium, and its associated microbiota. This led us to hypothesise that specific features of the early life microbiome could predict calf susceptibility to C. parvum infection. In this study, a single faecal swab sample was collected from each calf within the first week of life in a cohort of 346 animals. All 346 calves were subsequently monitored for clinical signs of cryptosporidiosis, and calves that developed diarrhoea were tested for Rotavirus, Coronavirus, E. coli F5 (K99) and C. parvum by lateral flow test (LFT). A retrospective case–control approach was taken whereby a subset of healthy calves (Control group; n = 33) and calves that went on to develop clinical signs of infectious diarrhoea and test positive for C. parvum infection via LFT (Cryptosporidium-positive group; n = 32) were selected from this cohort, five of which were excluded due to low DNA quality. A metagenomic analysis was conducted on the faecal microbiomes of the control group (n = 30) and the Cryptosporidium-positive group (n = 30) prior to infection, to determine features predictive of cryptosporidiosis. Taxonomic analysis showed no significant differences in alpha diversity, beta diversity, and taxa relative abundance between controls and Cryptosporidium-positive groups. Analysis of functional potential showed pathways related to isoprenoid precursor, haem and purine biosynthesis were significantly higher in abundance in calves that later tested positive for C. parvum (q ≤ 0.25). These pathways are either absent or streamlined in the C. parvum parasites. Though the de novo production of isoprenoid precursors, haem and purines are absent, C. parvum has been shown to encode enzymes that catalyse the downstream reactions of these pathway metabolites, indicating that C. parvum may scavenge those products from an external source. The host has previously been put forward as the source of essential metabolites, but our study suggests that C. parvum may also be able to harness specific metabolic pathways of the microbiota in order to survive and replicate. This finding is important as components of these microbial pathways could be exploited as potential therapeutic targets for the prevention or mitigation of cryptosporidiosis in bovine neonates

Measurements of Ice Shelf Water beneath the front of the Ross Ice Shelf using gliders

Measurements made by an underwater glider deployed near the Ross Ice Shelf were used to identify the presence of Ice Shelf Water (ISW), which is defined as seawater with its potential temperature lower than its surface freezing point temperature. Properties logged by the glider included in situ temperature, electrical conductivity, pressure, GPS location at surfacings and time. For most of the first 30 recorded dives of its deployment, evidence suggests the glider was prevented from surfacing due to being under the ice shelf. For dives under the ice shelf, farthest from the ice shelf front, ISW layers of varying thicknesses and depth locations were observed; between 2 m thick (centred at 231 m depth) to >93 m thick (centred at >360 m). For dives under the ice shelf, close to the ice shelf front, either no ISW was observed or ISW layers were centred at shallower depths (116–127 m). Thicker ISW layers (e.g. up to 250 m thickness centred at 421 m) were observed for some glider dives in open water in front of the Ross Ice Shelf. No in situ supercooling (water colder than the pressure-dependent freezing point temperature) was observed

Feasibility of a healthcare system-based tetralogy of Fallot patient registry

Background Patient-reported outcomes and epidemiological studies in adults with tetralogy of Fallot are lacking. Recruitment and longitudinal follow-up investigation across institutions is particularly challenging. Objectives of this study were to assess the feasibility of recruiting adult patients with tetralogy of Fallot for a patient-reported outcomes study, describe challenges for recruitment, and create an interactive, online tetralogy of Fallot registry. Methods Adult patients living with tetralogy of Fallot, aged 18-58 years, at the University of North Carolina were identified using diagnosis code query. A survey was designed to collect demographics, symptoms, history, and birth mother information. Recruitment was attempted by phone (Part I, n=20) or by email (Part II, n=20). Data analysis included thematic grouping of recruitment challenges and descriptive statistics. Feasibility threshold was 75% for recruitment and for data fields completed per patient. Results In Part I, 60% (12/20) were successfully contacted and eight (40%) were enrolled. Demographics and birth mother information were obtained for all enrolled patients. In Part II, 70% (14/20) were successfully contacted; 30% (6/20) enrolled and completed all data fields linked to REDCap database; the median time for survey completion was 8 minutes. Half of the patients had cardiac operations/procedures performed at more than one hospital. Automatic electronic data entry from the online survey was uncomplicated. Conclusions Although recruitment (54%) fell below our feasibility threshold, enrolled individuals were willing to complete phone or online surveys. Incorrect contact information, privacy concerns, and patient-reported time constraints were challenges for recruitment. Creating an online survey and linked database is technically feasible and efficient for patient-reported outcomes research