Preliminary design of an intermittent smoke flow visualization system

A prototype intermittent flow visualization system that was designed to study vortex flow field dynamics has been constructed and tested through its ground test phase. It produces discrete pulses of dense white smoke consisting of particles of terephthalic acid by the pulsing action of a fast-acting three-way valve. The trajectories of the smoke pulses can be tracked by a video imaging system without intruding in the flow around in flight. Two methods of pulsing the smoke were examined. The simplest and safest approach is to simply divert the smoke between the two outlet ports on the valve; this approach should be particularly effective if it were desired to inject smoke at two locations during the same test event. The second approach involves closing off one of the outlet ports to momentarily block the flow. The second approach requires careful control of valve dwell times to avoid excessive pressure buildup within the cartridge container. This method also increases the velocity of the smoke injected into the flow. The flow of the smoke has been blocked for periods ranging from 30 to 80 milliseconds, depending on the system volume and the length of time the valve is allowed to remain open between valve closings

Mesoscopic superpositions of vibronic collective states of N trapped ions

We propose a scalable procedure to generate entangled superpositions of motional coherent states and electronic states in N trapped ions. Beyond their fundamental importance, these states may be of interest for quantum information processing and may be used in experimental studies of decoherence.Comment: Final version, as published in Physical Review Letters. See also further developments and applications in quant-ph/020207

Dynamical response of a Bose-Einstein condensate to a discontinuous change in internal state

A two-photon transition is used to convert an arbitrary fraction of the 87Rb atoms in a |F=1,m_f=-1> condensate to the |F=2,m_f=1> state. Transferring the entire population imposes a discontinuous change on the condensate's mean-field repulsion, which leaves a residual ringing in the condensate width. A calculation based on Gross-Pitaevskii theory agrees well with the observed behavior, and from the comparison we obtain the ratio of the intraspecies scattering lengths for the two states, a_|1,-1> / a_|2,1> = 1.062(12).Comment: 4 pages, 3 figure

Engineering arbitrary motional ionic state through realistic intensity-fluctuating laser pulses

We present a reliable scheme for engineering arbitrary motional ionic states through an adaptation of the projection synthesis technique for trapped-ion phenomena. Starting from a prepared coherent motional state, the Wigner function of the desired state is thus sculpted from a Gaussian distribution. The engineering process has also been developed to take into account the errors arising from intensity fluctuations in the exciting-laser pulses required for manipulating the electronic and vibrational states of the trapped ion. To this end, a recently developed phenomenological-operator approach that allows for the influence of noise will be applied. This approach furnishes a straightforward technique to estimate the fidelity of the prepared state in the presence of errors, precluding the usual extensive ab initio calculations. The results obtained here by the phenomenological approach, to account for the effects of noise in our engineering scheme, can be directly applied to any other process involving trapped-ion phenomena.Comment: more information at http://www.df.ufscar.br/~quantum

HIV Drug Resistance Surveillance Using Pooled Pyrosequencing

BACKGROUND: Surveillance for HIV transmitted drug resistance (TDR) is performed using HIV genotype results from individual specimens. Pyrosequencing, through its massive parallel sequencing ability, can analyze large numbers of specimens simultaneously. Instead of using pyrosequencing conventionally, to sequence a population of viruses within an individual, we interrogated a single combined pool of surveillance specimens to demonstrate that it is possible to determine TDR rates in HIV protease from a population of individuals. METHODOLOGY/PRINCIPAL FINDINGS: The protease region from 96 treatment naïve, HIV+ serum specimens was genotyped using standard Sanger sequencing method. The 462 bp protease amplicons from these specimens were pooled in equimolar concentrations and re-sequenced using the GS FLX Titanium system. The nucleotide (NT) and amino acid (AA) differences from the reference sequence, along with TDR mutations, detected by each method were compared. In the protease sequence, there were 212 nucleotide and 81 AA differences found using conventional sequencing and 345 nucleotide and 168 AA differences using pyrosequencing. All nucleotide and amino acid polymorphisms found at frequencies >/=5% in pyrosequencing were detected using both methods with the rates of variation highly correlated. Using Sanger sequencing, two TDR mutations, M46L and I84V, were each detected as mixtures at a frequency of 1.04% (1/96). These same TDR mutations were detected by pyrosequencing with a prevalence of 0.29% and 0.34% respectively. Phylogenetic analysis established that the detected low frequency mutations arose from the same single specimens that were found to contain TDR mutations by Sanger sequencing. Multiple clinical protease DR mutations present at higher frequencies were concordantly identified using both methods. CONCLUSIONS/SIGNIFICANCE: We show that pyrosequencing pooled surveillance specimens can cost-competitively detect protease TDR mutations when compared with conventional methods. With few modifications, the method described here can be used to determine population rates of TDR in both protease and reverse transcriptase. Furthermore, this pooled pyrosequencing technique may be generalizable to other infectious agents where a survey of DR rates is required

Diarrhoea Complicating Severe Acute Malnutrition in Kenyan Children: A Prospective Descriptive Study of Risk Factors and Outcome

BACKGROUND: Severe acute malnutrition (SAM) accounts for two million deaths worldwide annually. In those hospitalised with SAM, concomitant infections and diarrhoea are frequent complications resulting in adverse outcome. We examined the clinical and laboratory features on admission and outcome of children with SAM and diarrhoea at a Kenyan district hospital. METHODS: A 4-year prospective descriptive study involving 1,206 children aged 6 months to 12 years, hospitalized with SAM and managed in accordance with WHO guidelines. Data on clinical features, haematological, biochemical and microbiological findings for children with diarrhoea (≥ 3 watery stools/day) were systematically collected and analyzed to identify risk factors associated with poor outcome. RESULTS: At admission 592 children (49%) had diarrhoea of which 122 (21%) died compared to 72/614 (12%) deaths in those without diarrhoea at admission (Χ(2) = 17.6 p<0.001). A further 187 (16%) children developed diarrhoea after 48 hours of admission and 33 died (18%). Any diarrhoea during admission resulted in a significantly higher mortality 161/852 (19%) than those uncomplicated by diarrhoea 33/351 (9%) (Χ(2) = 16.6 p<0.001). Features associated with a fatal outcome in children presenting with diarrhoea included bacteraemia, hyponatraemia, low mid-upper arm circumference <10 cm, hypoxia, hypokalaemia and oedema. Bacteraemia had the highest risk of death (adjusted OR 6.1; 95% C.I 2.3, 16.3 p<0.001); and complicated 24 (20%) of fatalities. Positive HIV antibody status was more frequent in cases with diarrhoea at admission (23%) than those without (15%, Χ(2) = 12.0 p = 0.001) but did not increase the risk of death in diarrhoea cases. CONCLUSION: Children with SAM complicated by diarrhoea had a higher risk of death than those who did not have diarrhoea during their hospital stay. Further operational and clinical research is needed to reduce mortality in children with SAM in the given setting

Effectiveness of Air Filters and Air Cleaners in Allergic Respiratory Diseases: A Review of the Recent Literature

Air filtration is frequently recommended as a component of environmental control measures for patients with allergic respiratory disease. Residential air filtration can be provided by whole house filtration via the home’s heating, ventilation, or air conditioning system, by portable room air cleaners, or a combination of the two. Appliances to filter the sleep breathing zone also have been developed. High-efficiency whole house filtration, high-efficiency particulate air sleep zone air filtration, and high-efficiency particulate air room air cleaners all appear to provide various degrees of benefit. Recent studies of various types of filtration, used alone or as part of more comprehensive environmental control measures, are reviewed

Linear Optics Simulation of Non-Markovian Quantum Dynamics

The simulation of quantum processes is a key goal for the grand programme aiming at grounding quantum technologies as the way to explore complex phenomena that are inaccessible through standard, classical calculators. Some interesting steps have been performed in this direction and this scenario has recently been extended to open quantum evolutions, marking the possibility to investigate important features of the way a quantum system interacts with its environment. Here we demonstrate experimentally the (non-)Markovianity of a process where system and environment are coupled through a simulated transverse Ising model. By engineering the evolution in a fully controlled photonic quantum simulator, we assess and demonstrate the role that system-environment correlations have in the emergence of memory effects.Comment: 4+2 pages, 4 figures, RevTeX