Heat transfer device

A heat transfer device is characterized by an hermetically sealed tubular housing including a tubular shell terminating in spaced end plates, and a tubular mesh wick concentrically arranged and operatively supported within said housing. The invention provides an improved wicking restraint formed as an elongated and radially expanded tubular helix concentrically related to the wick and adapted to be axially foreshortened and radially expanded into engagement with the wick in response to an axially applied compressive load. The wick is continuously supported in a contiguous relationship with the internal surfaces of the shell

Measuring the quantum efficiency of single radiating dipoles using a scanning mirror

Using scanning probe techniques, we show the controlled manipulation of the radiation from single dipoles. In one experiment we study the modification of the fluorescence lifetime of a single molecular dipole in front of a movable silver mirror. A second experiment demonstrates the changing plasmon spectrum of a gold nanoparticle in front of a dielectric mirror. Comparison of our data with theoretical models allows determination of the quantum efficiency of each radiating dipole.Comment: 4 pages, 4 figure

Effects of HEPA Air Cleaners on Unscheduled Asthma Visits and Asthma Symptoms for Children Exposed to Secondhand Tobacco Smoke

The goal was to test the effects of high-efficiency, particulate-arresting (HEPA) air cleaners on unscheduled asthma visits and symptoms among children with asthma exposed to secondhand smoke

Coupling of plasmonic nanoparticles to their environments in the context of van der Waals-Casimir interactions

We present experiments in which the interaction of a single gold nanoparticle with glass substrates or with another gold particle can be tuned by in-situ control of their separations using scanning probe technology. We record the plasmon resonances of the coupled systems as a function of the polarization of the incident field and the particle position. The distinct spectral changes of the scattered light from the particle pair are in good agreement with the outcome of finite difference time-domain (FDTD) calculations. We believe our experimental technique holds promise for the investigation of the van der Waals-Casimir type interactions between nanoscopic neutral bodies.Comment: 9 pages, 7 figure

Selective nanomanipulation using optical forces

We present a detailed theoretical study of the recent proposal for selective nanomanipulation of nanometric particles above a substrate using near-field optical forces [Chaumet {\it et al.} Phys. Rev. Lett. {\bf 88}, 123601 (2002)]. Evanescent light scattering at the apex of an apertureless near-field probe is used to create an optical trap. The position of the trap is controlled on a nanometric scale via the probe and small objects can be selectively trapped and manipulated. We discuss the influence of the geometry of the particles and the probe on the efficiency of the trap. We also consider the influence of multiple scattering among the particles on the substrate and its effect on the robustness of the trap.Comment: 12 pages, 17 figure

Efficient preparation of internally modified single-molecule constructs using nicking enzymes

Investigations of enzymes involved in DNA metabolism have strongly benefited from the establishment of single molecule techniques. These experiments frequently require elaborate DNA substrates, which carry chemical labels or nucleic acid tertiary structures. Preparing such constructs often represents a technical challenge: long modified DNA molecules are usually produced via multi-step processes, involving low efficiency intermolecular ligations of several fragments. Here, we show how long stretches of DNA (>50 bp) can be modified using nicking enzymes to produce complex DNA constructs. Multiple different chemical and structural modifications can be placed internally along DNA, in a specific and precise manner. Furthermore, the nicks created can be resealed efficiently yielding intact molecules, whose mechanical properties are preserved. Additionally, the same strategy is applied to obtain long single-strand overhangs subsequently used for efficient ligation of ss- to dsDNA molecules. This technique offers promise for a wide range of applications, in particular single-molecule experiments, where frequently multiple internal DNA modifications are required

Characterization and comparison of a 2-, 4- and 8-MHz central venous catheter ultrasound probe for venous air emboli detection

This paper presents a concept for detection of venous air emboli inside the superior vena cava using a central venous catheter with integrated Doppler ultrasound transducer installed on the tip. Several Doppler probes each with a single insonation frequencies of 2 MHz, 4 MHz or 8 MHz are characterized and compared for usefulness in this scenario. During in vitro experiments using an artificial blood circulatory with blood mimicking fluid bubbles with defined volumes were injected and recorded as gaseous embolic events. The in vitro results of measured embolus-blood-ratio values (EBR) in respect to the air bubbles volumes and its echogenicity showed a good correlation with the simulation model of spherical cross section scattering of such air bubbles. It is shown that the probe design still needs some improvements using a 4 MHz insonation frequency to get a useable detection sensitivity in such scenario within vena cava superior. The results suggest that it is possible to estimate the air bubble volume corresponding to the EBR using such a catheter probe.In diesem Beitrag wird ein Konzept zur Erkennung von venösen Luftembolien in der oberen Hohlvene vorgestellt, bei dem ein zentraler Venenkatheter mit integriertem Doppler-Ultraschallwandler an der Spitze genutzt wird. Mehrere Doppler-Sonden mit jeweils einer einzelnen Beschallungsfrequenz von 2 MHz, 4 MHz oder 8 MHz werden charakterisiert und auf ihre Nützlichkeit in diesem Szenario verglichen. Bei in vitro Experimenten mit einem künstlichen Blutkreislauf mit Blutsimulatinsflüssigkeit wurden Blasen mit definierten Volumina injiziert und aufgezeichnet. Die in vitro Ergebnisse der gemessenen Embolus-Blood-Ratio-Werte (EBR) in Bezug auf die Luftblasenvolumina und ihre Echogenität zeigten eine gute Korrelation mit dem Simulationsmodell der Streuung solcher Luftblasen im Kugelquerschnitt. Es zeigt sich, dass das Design der Sonde bei Verwendung einer 4 MHz-Insonationsfrequenz noch einiger Verbesserungen bedarf, um eine brauchbare Detektionsempfindlichkeit in einem solchen Szenario innerhalb der Vena cava superior zu erhalten. Die Ergebnisse legen nahe, dass es möglich ist, die Luftblasenvolumina abzuschätzen, die der EBR mit einer solchen Kathetersonde entsprechen

Automatische Schlafstadienklassifizierung basierend auf Körperschall und Aktigraphie

The current gold standard for assessment of most sleep disorders is the in-laboratory polysomnography (PSG). This approach produces high costs and inconveniences for the patients. An accessible and simple preliminary screening method to diagnose the most common sleep disorders and to decide whether a PSG is necessary or not is therefore desirable. A minimalistic type-4 monitoring system which utilized tracheal body sound and actigraphy to accurately diagnose the obstructive sleep apnea syndrome was previously developed. To further improve the diagnostic ability of said system, this study aims to examine if it is possible to perform automated sleep staging utilizing body sound to extract cardiorespiratory features and actigraphy to extract movement features.A linear discriminant classifier based on those features was used for automated sleep staging using the type-4 sleep monitor. For validation 53 subjects underwent a full-night screening at Ulm University Hospital using the developed sleep monitor in addition to polysomnography. To assess sleep stages from PSG, a trained technician manually evaluated EEG, EOG, and EMG recordings. The classifier reached 86.9% accuracy and a Kappa of 0.69 for sleep/wake classification, 76.3% accuracy and a Kappa of 0.42 for Wake/REM/NREM classification, and 56.5% accuracy and a Kappa of 0.36 for Wake/REM/light sleep/deep sleep classification. For the calculation of sleep efficiency (SE), a coefficient of determination r2 of 0.78 is reached. Additionally, subjects were classified into groups of SEs (SE>=40%, SE>=60% and SE>=80%). A Cohen's Kappa >0.61 was reached for all groups, which is considered as substantial agreement.The presented method provides satisfactory performance in sleep/wake and wake/REM/NREM sleep staging while maintaining a simple setup and offering high comfort. This minimalistic approach may address the need for a simple yet reliable preliminary sleep screening in an ambulatory setting.Der aktuelle Goldstandard für die Beurteilung der meisten Schlafstörungen ist die Polysomnographie (PSG). Diese Methode der Diagnose ist mit hohen Kosten und Unannehmlichkeiten für die Patienten verbunden. Eine einfache Methode der Diagnose der häufigsten Schlafstörungen ist daher wünschenswert. Hierzu wurde ein minimalistischer Typ-4-Schlafmonitor, welcher Körperschall und Aktigraphie zur Diagnose des obstruktiven Schlafapnoe-Syndroms einsetzt, entwickelt. Um die Diagnosefähigkeit dieses Systems zu erweitern, soll in dieser Studie untersucht werden, ob der Schlafmonitor automatisiert Schlafstadien klassifizieren kann. Hierbei wird Körperschall verwendet, um kardiorespiratorische Merkmale zu extrahieren, und Aktigraphie, um Bewegungsmerkmale zu extrahieren.Ein auf diesen Merkmalen basierender linearer Diskriminanzklassifizierer wurde für die automatisierte Klassifizierung von Schlafstadien mit dem vorgestellten Typ-4-Schlafmonitor verwendet. Zur Validierung wurden 53 Probanden am Universitätsklinikum Ulm zusätzlich zur PSG einem nächtlichen Screening mit dem entwickelten Schlafmonitor unterzogen. Zur Beurteilung der Schlafstadien der PSG hat ein geschulter Techniker EEG-, EOG- und EMG-Aufnahmen manuell ausgewertet. Der Klassifikator erreichte eine Genauigkeit von 86,9% und ein Kappa von 0,69 für Schlaf/Wach-Klassifizierung, 76,3% Genauigkeit und ein Kappa von 0,42 für Wach/REM/NREM-Klassifizierung, und 56,5% Genauigkeit und ein Kappa von 0,36 für Wach/REM/Leichtschlaf/Tiefschlaf-Klassifizierung. Für die Berechnung der Schlafeffizienz (SE) wird ein Bestimmtheitsmaß r2 von 0,78 erreicht. Zusätzlich wurden die Probanden in Gruppen von SEs eingeteilt (SE>=40%, SE>=60% und SE>=80%). Ein Cohen's Kappa >0,61 wurde für alle Gruppen erreicht, was als substantielle Übereinstimmung angesehen wird.Die vorgestellte Methode bietet eine zufriedenstellende Leistung in der Schlaf/Wach- und Wach/REM/NREM-Schlaf-Klassifizierung bei einfachem Aufbau und hohem Patientenkomfort. Dieser minimalistische Ansatz kann den Bedarf an einem einfachen aber zuverlässigen Vorab-Schlaf-Screening im ambulanten Bereich abdecken

Effects of HEPA Air Cleaners on Unscheduled Asthma Visits and Asthma Symptoms for Children Exposed to Secondhand Tobacco Smoke

OBJECTIVE: The goal was to test the effects of high-efficiency, particulate-arresting (HEPA) air cleaners on unscheduled asthma visits and symptoms among children with asthma exposed to secondhand smoke. METHODS: We enrolled 225 eligible children who were 6 to 12 years of age, had physician-diagnosed asthma, and were exposed to ≥5 cigarettes per day. We conducted a double-blind, randomized trial. Children were assigned randomly to receive 2 active or inactive HEPA air cleaners. RESULTS: Of 225 enrolled children, 110 (49%) were assigned to the intervention group and 115 (51%) to the control group; 215 (95%) completed the trial. During the trial, there were 42 fewer unscheduled asthma visits among children in the intervention group (18.5% [95% confidence interval: 1.25%–82.75%]; P = .043), compared with those in the control group, after adjustment for baseline differences. There was a significant difference in the reductions of levels of particles of >0.3 μm according to group assignment; there was a 25% reduction in particle levels in the intervention group, compared with a 5% reduction in the control group (P = .026). There were no significant differences in parent-reported asthma symptoms, exhaled nitric-oxide levels, air nicotine levels, or cotinine levels according to group assignment. CONCLUSIONS: These results hold promise for using HEPA air cleaners as part of a multifaceted strategy to reduce asthma morbidity, but further research is necessary before they can be recommended routinely for the medical management of asthma