Refining Nodes and Edges of State Machines

State machines are hierarchical automata that are widely used to structure complex behavioural specifications. We develop two notions of refinement of state machines, node refinement and edge refinement. We compare the two notions by means of examples and argue that, by adopting simple conventions, they can be combined into one method of refinement. In the combined method, node refinement can be used to develop architectural aspects of a model and edge refinement to develop algorithmic aspects. The two notions of refinement are grounded in previous work. Event-B is used as the foundation for our refinement theory and UML-B state machine refinement influences the style of node refinement. Hence we propose a method with direct proof of state machine refinement avoiding the detour via Event-B that is needed by UML-B

Exciting, Cooling And Vortex Trapping In A Bose-Condensed Gas

A straight forward numerical technique, based on the Gross-Pitaevskii equation, is used to generate a self-consistent description of thermally-excited states of a dilute boson gas. The process of evaporative cooling is then modelled by following the time evolution of the system using the same equation. It is shown that the subsequent rethermalisation of the thermally-excited state produces a cooler coherent condensate. Other results presented show that trapping vortex states with the ground state may be possible in a two-dimensional experimental environment.Comment: 9 pages, 7 figures. It's worth the wait! To be published in Physical Review A, 1st February 199

Thermodynamics of an interacting trapped Bose-Einstein gas in the classical field approximation

We present a convenient technique describing the condensate in dynamical equilibrium with the thermal cloud, at temperatures close to the critical one. We show that the whole isolated system may be viewed as a single classical field undergoing nonlinear dynamics leading to a steady state. In our procedure it is the observation process and the finite detection time that allow for splitting the system into the condensate and the thermal cloud.Comment: 4 pages, 4 eps figures, final versio

Lombardi Drawings of Graphs

We introduce the notion of Lombardi graph drawings, named after the American abstract artist Mark Lombardi. In these drawings, edges are represented as circular arcs rather than as line segments or polylines, and the vertices have perfect angular resolution: the edges are equally spaced around each vertex. We describe algorithms for finding Lombardi drawings of regular graphs, graphs of bounded degeneracy, and certain families of planar graphs.Comment: Expanded version of paper appearing in the 18th International Symposium on Graph Drawing (GD 2010). 13 pages, 7 figure

Detection and molecular characterisation of Cryptosporidium parvum in British European hedgehogs (Erinaceus europaeus)

Surveillance was conducted for the occurrence of protozoan parasites of the genus Cryptosporidium in European hedgehogs (Erinaceus europaeus) in Great Britain. In total, 108 voided faecal samples were collected from hedgehogs newly admitted to eight wildlife casualty treatment and rehabilitation centres. Terminal large intestinal (LI) contents from three hedgehog carcasses were also analysed. Information on host and location variables, including faecal appearance, body weight, and apparent health status, was compiled. Polymerase Chain Reaction (PCR) targeting the 18S ribosomal RNA gene, confirmed by sequencing, revealed an 8% (9/111) occurrence of Cryptosporidium parvum in faeces or LI contents, with no significant association between the host or location variables and infection. Archived small intestinal (SI) tissue from a hedgehog with histological evidence of cryptosporidiosis was also positive for C. parvum by PCR and sequence analysis of the 18S rRNA gene. No other Cryptosporidium species were detected. PCR and sequencing of the glycoprotein 60 gene identified three known zoonotic C. parvum subtypes not previously found in hedgehogs: IIdA17G1 (n=4), IIdA19G1 (n=1) and IIdA24G1 (n=1). These subtypes are also known to infect livestock. Another faecal sample contained C. parvum IIcA5G3j which has been found previously in hedgehogs, and for which there is one published report in a human, but is not known to affect livestock. The presence of zoonotic subtypes of C. parvum in British hedgehogs highlights a potential public health concern. Further research is needed to better understand the epidemiology and potential impacts of Cryptosporidium infection in hedgehogs

Quantum Kinetic Theory V: Quantum kinetic master equation for mutual interaction of condensate and noncondensate

A detailed quantum kinetic master equation is developed which couples the kinetics of a trapped condensate to the vapor of non-condensed particles. This generalizes previous work which treated the vapor as being undepleted.Comment: RevTeX, 26 pages and 5 eps figure

Cohesin mutations alter DNA damage repair and chromatin structure and create therapeutic vulnerabilities in MDS/AML

The cohesin complex plays an essential role in chromosome maintenance and transcriptional regulation. Recurrent somatic mutations in the cohesin complex are frequent genetic drivers in cancer including myelodysplatic syndromes (MDS) and acute myeloid leukemia (AML). Here, using genetic dependency screens of STAG2-mutant AML, we identified DNA damage repair and replication as genetic dependencies in cohesin-mutant cells. We demonstrated increased levels of DNA damage and sensitivity of cohesin-mutant cells to PARP inhibition. We developed a mouse model of MDS in which Stag2 mutations arise as clonal secondary lesions in the background of clonal hematopoiesis driven by Tet2 mutations, and demonstrated selective depletion of cohesin-mutant cells with PARP inhibition in vivo. Finally, we demonstrated a shift from STAG2- to STAG1-containing cohesin complexes in cohesin-mutant cells, which is associated with longer DNA loop extrusion, more intermixing of chromatin compartments, and increased interaction with PARP and RPA proteins. Our findings inform the biology and therapeutic opportunities for cohesin-mutant malignancies

Quantum Kinetic Theory III: Quantum kinetic master equation for strongly condensed trapped systems

We extend quantum kinetic theory to deal with a strongly Bose-condensed atomic vapor in a trap. The method assumes that the majority of the vapor is not condensed, and acts as a bath of heat and atoms for the condensate. The condensate is described by the particle number conserving Bogoliubov method developed by one of the authors. We derive equations which describe the fluctuations of particle number and phase, and the growth of the Bose-Einstein condensate. The equilibrium state of the condensate is a mixture of states with different numbers of particles and quasiparticles. It is not a quantum superposition of states with different numbers of particles---nevertheless, the stationary state exhibits the property of off-diagonal long range order, to the extent that this concept makes sense in a tightly trapped condensate.Comment: 3 figures submitted to Physical Review

A CsI(Tl) Scintillating Crystal Detector for the Studies of Low Energy Neutrino Interactions

Scintillating crystal detector may offer some potential advantages in the low-energy, low-background experiments. A 500 kg CsI(Tl) detector to be placed near the core of Nuclear Power Station II in Taiwan is being constructed for the studies of electron-neutrino scatterings and other keV-MeV range neutrino interactions. The motivations of this detector approach, the physics to be addressed, the basic experimental design, and the characteristic performance of prototype modules are described. The expected background channels and their experimental handles are discussed.Comment: 34 pages, 11 figures, submitted to Nucl. Instrum. Method

Relationship Between Venules and Perivascular Spaces in Sporadic Small Vessel Diseases

Background and Purpose— Perivascular spaces (PVS) around venules may help drain interstitial fluid from the brain. We examined relationships between suspected venules and PVS visible on brain magnetic resonance imaging. Methods— We developed a visual venular quantification method to examine the spatial relationship between venules and PVS. We recruited patients with lacunar stroke or minor nondisabling ischemic stroke and performed brain magnetic resonance imaging and retinal imaging. We quantified venules on gradient echo or susceptibility-weighted imaging and PVS on T2-weighted magnetic resonance imaging in the centrum semiovale and then determined overlap between venules and PVS. We assessed associations between venular count and patient demographic characteristics, vascular risk factors, small vessel disease features, retinal vessels, and venous sinus pulsatility. Results— Among 67 patients (69% men, 69.0±9.8 years), only 4.6% (range, 0%–18%) of venules overlapped with PVS. Total venular count increased with total centrum semiovale PVS count in 55 patients after accounting for venule-PVS overlap (β=0.468 [95% CI, 0.187–0.750]) and transverse sinus pulsatility (β=0.547 [95% CI, 0.309–0.786]) and adjusting for age, sex, and systolic blood pressure. Conclusions— Despite increases in both visible PVS and suspected venules, we found minimal spatial overlap between them in patients with sporadic small vessel disease, suggesting that most magnetic resonance imaging-visible centrum semiovale PVS are periarteriolar rather than perivenular