Magnetised quark nuggets in the atmosphere.

A search for magnetised quark nuggets (MQN) is reported using acoustic signals from hydrophones placed in the Great Salt Lake (GSL) in the USA. No events satisfying the expected signature were seen. This observation allows limits to be set on the flux of MQNs penetrating the Earth's atmosphere and depositing energy in the GSL. The expected signature of the events was ​derived from pressure pulses caused by high-explosive cords between the lake surface and bottom at various locations in the GSL. The limits obtained from this search are compared with those obtained from previous searches and are compared to models for the formation of MQNs.

Mass distribution of magnetized quark-nugget dark matter and comparison with requirements and observations.

Quark nuggets are a candidate for dark matter consistent with the Standard Model. Previous models of quark nuggets have investigated properties arising from their being composed of strange, up, and down quarks and have not included any effects caused by their self-magnetic field. However, Tatsumi found that the core of a magnetar star may be a quark nugget in a ferromagnetic state with core magnetic field Bsurface = 1012±1 T. We apply Tatsumi's result to quark-nugget dark-matter and report results on aggregation of magnetized quark nuggets (MQNs) after formation from the quark-gluon plasma until expansion of the universe freezes out the mass distribution to ~ 10-24 kg to ~ 1014 kg. Aggregation overcomes weak-interaction decay. Computed mass distributions show MQNs are consistent with requirements for dark matter and indicate that geologic detectors (craters in peat bogs) and space-based detectors (satellites measuring radio-frequency emissions after passage through normal matter) should be able to detect MQN dark matter. Null and positive observations narrow the range of a key parameter Bo ~ Bsurface to 1 × 1011 T < Bo ≤ 3 × 1012 T.

Detection of magnetized quark-nuggets, a candidate for dark matter.

Quark nuggets are theoretical objects composed of approximately equal numbers of up, down, and strange quarks and are also called strangelets and nuclearites. They have been proposed as a candidate for dark matter, which constitutes ~85% of the universe's mass and which has been a mystery for decades. Previous efforts to detect quark nuggets assumed that the nuclear-density core interacts directly with the surrounding matter so the stopping power is minimal. Tatsumi found that quark nuggets could well exist as a ferromagnetic liquid with a ~1012-T magnetic field. We find that the magnetic field produces a magnetopause with surrounding plasma, as the earth's magnetic field produces a magnetopause with the solar wind, and substantially increases their energy deposition rate in matter. We use the magnetopause model to compute the energy deposition as a function of quark-nugget mass and to analyze testing the quark-nugget hypothesis for dark matter by observations in air, water, and land. We conclude the water option is most promising.

Exploiting parallel R in the cloud with SPRINT.

BACKGROUND: Advances in DNA Microarray devices and next-generation massively parallel DNA sequencing platforms have led to an exponential growth in data availability but the arising opportunities require adequate computing resources. High Performance Computing (HPC) in the Cloud offers an affordable way of meeting this need. OBJECTIVES: Bioconductor, a popular tool for high-throughput genomic data analysis, is distributed as add-on modules for the R statistical programming language but R has no native capabilities for exploiting multi-processor architectures. SPRINT is an R package that enables easy access to HPC for genomics researchers. This paper investigates: setting up and running SPRINT-enabled genomic analyses on Amazon's Elastic Compute Cloud (EC2), the advantages of submitting applications to EC2 from different parts of the world and, if resource underutilization can improve application performance. METHODS: The SPRINT parallel implementations of correlation, permutation testing, partitioning around medoids and the multi-purpose papply have been benchmarked on data sets of various size on Amazon EC2. Jobs have been submitted from both the UK and Thailand to investigate monetary differences. RESULTS: It is possible to obtain good, scalable performance but the level of improvement is dependent upon the nature of the algorithm. Resource underutilization can further improve the time to result. End-user's location impacts on costs due to factors such as local taxation. CONCLUSIONS: Although not designed to satisfy HPC requirements, Amazon EC2 and cloud computing in general provides an interesting alternative and provides new possibilities for smaller organisations with limited funds.

Search for magnetic monopoles in polar volcanic rocks.

For a broad range of values of magnetic monopole mass and charge, the abundance of monopoles trapped inside Earth would be expected to be enhanced in the mantle beneath the geomagnetic poles. A search for magnetic monopoles was conducted using the signature of an induced persistent current following the passage of igneous rock samples through a SQUID-based magnetometer. A total of 24.6 kg of rocks from various selected sites, among which 23.4 kg are mantle-derived rocks from the Arctic and Antarctic areas, was analyzed. No monopoles were found, and a 90% confidence level upper limit of 9.8 × 10(-5)/g is set on the monopole density in the search samples.

Effect of a pathway bundle on length of stay.

BACKGROUND: Pathways to guide clinical care are well accepted and used in many emergency departments. We wanted to introduce a number ("bundle") over a short space of time and involve the whole patient stay in the pathway. It was hypothesised that a more efficient process would result with an overall reduction in length of stay (LoS). METHODS: A "bundle" of 14 evidence-based pathways of care was introduced into a medium-sized district general hospital (DGH) in late 2006/early 2007. These pathways covered emergency department care and acute medical care for a period of up to 48 h. A total of 8184 acute emergency admission episodes were audited, 3852 in the 8 months before introduction of the new pathways and 4332 in the 8 months after their introduction. RESULTS: The overall effect of introducing the pathway bundle had a trend towards reduction in LoS by 0.2 days (95% CI -0.2 to 0.5), but this was not statistically significant (p>0.1). However, in those patients with

The subclavian and axillary arteries as inflow vessels for coronary artery bypass grafts--combined experience from three cardiac surgery centers.

BACKGROUND: The subclavian and axillary arteries represent reliable inflow vessels in peripheral vascular surgery. During recent years they have also been used for special situations in coronary artery bypass grafting. We report on a preliminary, triple center experience with subclavian/axillary artery to coronary artery bypass grafting. METHODS: Twenty-one patients (11 male, 10 female, median age 70 years) received subclavian artery/axillary artery to coronary artery bypass grafts. Indications for application of this bypass variation were internal mammary artery problems during minimally invasive coronary artery bypass grafting (n = 10), untouchable ascending aorta (n = 6), high risk reoperations (n = 3), severe chronic obstructive pulmonary disease (COPD) (n = 1) and right ventricular ischemia after ascending aortic replacement for acute aortic dissection type A (n = 1). Fourteen procedures were carried out via minithoracotomy, and seven via sternotomy. Inflow vessels were the left subclavian/axillary artery in 12 cases, the right subclavian/axillary artery in eight cases and bilateral subclavian/axillary artery in one case. Bypass conduits were the saphenous vein (n = 20 for revascularization of the left anterior descending artery, the right coronary artery and obtuse marginal branches) and the radial artery (n = 2 for revascularization of diagonal branches). RESULTS: The procedure was without major technical problems in all patients. Hospital mortality was 1/21. Neither brachial plexus injury nor arm ischemia occurred. Mean pre- and postoperative angina classification was 3.0 +/- 0.8 and 1.2 +/- 0.4 respectively (p < 0.001). After a mean follow-up period of seven months, one out of 14 axillocoronary vein grafts studied by ultrasonic duplex scan or angiography was found occluded. Graft patency could be demonstrated for an observation period of up to two years. CONCLUSION: Subclavian/axillary artery to coronary artery bypass is feasible and can be applied for complications in minimally invasive coronary artery bypass grafting, for redo operations and for management of the severely atherosclerotic ascending aorta. To reach the left anterior descending artery-system, the saphenous vein as well as the radial artery can be used. Complications concerning the infraclavicular incision seem to be no problem. Short-term patency rates are acceptable.

Stable five- and six-coordinated silicate anions in aqueous solution.

Addition of aliphatic polyols to aqueous silicate solutions is shown to yield high concentrations of stable polyolate complexes containing five- or six-coordinated silicon. Coordinating polyols require at least four hydroxy groups, two of which must be in threo configuration, and coordinate to silicon via hydroxy oxygens at chain positions on either side of the threo pair. The remarkable ease by which these simple sugar-like molecules react to form hypervalent silicon complexes in aqueous solution supports a long-standing supposition that such species play a significant role in the biological uptake and transport of silicon and in mineral diagenesis.

Effects of overlapping parametric resonances on the particle diffusion process.

The evolution of the beam distribution in a double-rf system with a phase modulation on either the primary or secondary rf cavity was measured. We find that the particle diffusion process obeys the Einstein relation if the phase space becomes globally chaotic. When dominant parametric resonances still exist in the phase space, particles stream along the separatrices of the dominant resonance, and the beam width exhibits characteristic oscillatory structure. The particle-tracking simulations for the double-rf system are employed to reveal the essential diffusion mechanism. Coherent octupolar motion has been observed in the bunch beam excitation. The evolution of the longitudinal phase space in the octupole mode is displayed.

Minimally invasive reoperation through a lateral thoracotomy for circumflex coronary artery bypass.

We report 4 cases of redo coronary artery bypass grafting in which the circumflex coronary artery was successfully revascularized using a minimally invasive approach. In reoperative cases, it is easier to approach the circumflex coronary artery from the left side than from the front. Minimally invasive direct coronary artery bypass technology has made it possible to avoid using cardiopulmonary bypass. In our 4 cases, the revascularization procedure was performed via a small left thoracotomy, and without cardiopulmonary bypass. The patients made a good recovery and are free of angina 22 months after operation. We conclude that the thoracotomy approach provides the opportunity to avoid several hazards: a redo sternotomy, dissection of a hostile mediastinum, and manipulation of the heart.

Anesthetic effects on electrophysiologic recordings.

With the increased use of intraoperative monitoring of the central nervous system (CNS) has come a need for better understanding of the effects of anesthetic agents on intraoperative recordings. The commonly used anesthetic agents and their effects on intraoperative electroencephalography (EEG) and evoked potentials (EP) are discussed. Halogenated inhalational anesthetics produce dose-related reduction in EEG amplitude and frequency after an initial activation. They also produce dose-related decreases in amplitude and increases in latency of sensory evoked potentials (SEP) that are most marked in cortically generated components. Subcortical, spinal, and peripheral evoked responses are less affected. Responses in the motor pathways are recordable in the epidural space; however, the relative contributions of sensory and motor tracts may be changed when both are present. Muscle responses are easily suppressed after spinal and motor cortex stimulation, probably by anesthetic effect at the anterior horn cells of the spinal cord. Intravenous analgesic agents (opioids, ketamine) are associated with less marked changes in EEG and evoked responses, with some increases in amplitude of cortically generated SEP caused by ketamine. Intravenous sedative-hypnotic drugs (droperidol, barbiturates, benzodiazepines, etomidate, propofol) produce dose-related depression of the EEG after initial activation and dose-related depression of evoked responses to a lesser extent than do the inhalation agents. Etomidate is associated with amplitude enhancement of EEG and cortically generated SEP. Muscle relaxants have minimal effect on the EEG and SEP. Their use, however, may alter muscle recordings from motor tract stimulation. These effects and their relevance to the choice of agents for specific monitoring techniques are discussed.

Electrophysiologic monitoring in head injury.

Electrophysiologic monitoring of head-injured patients, using electroencephalogram (EEG) and sensory-evoked potentials, can provide a functional assessment of the neural structures involved in tested pathways. Experience using EEG, somatosensory-evoked potentials, brainstem auditory-evoked potentials, visual-evoked potentials, and the combination of sensory-evoked potentials termed multimodality-evoked potentials as clinical tools to augment patient evaluation and predict outcome demonstrates that these methods can be effectively integrated into clinical care. They can be used to augment the neurologic examination and provide useful information when other measures of neural function are limited by deep coma or by other treatment modalities that confound the clinical examination.

Multiple endocrine neoplasia syndrome, type III: review and case report.

Successful treatment of the multiple endocrine neoplasia type III (MEN III) syndrome requires early diagnosis. It is highly possible that the patient's dentist may be the first practitioner with the opportunity to diagnose this potentially fatal syndrome. Additionally, patients with this syndrome having a pheochromocytoma and needing invasive dental treatment pose a life-threatening dental management risk. This article presents a review of the MEN II syndrome and a case report on the surgical management of a MEN III patient with a pheochromocytoma.