Creation of an Ultracold Neutral Plasma

We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2 x 10^9 cm^-3, and the temperatures of electrons and ions are as low as 100 mK and 10 uK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.Comment: 4 pages, 3 figure

Clinicopathological determinants of an elevated systemic inflammatory response following elective potentially curative resection for colorectal cancer

Introduction: The postoperative systemic inflammatory response (SIR) is related to both long- and short-term outcomes following surgery for colorectal cancer. However, it is not clear which clinicopathological factors are associated with the magnitude of the postoperative SIR. The present study was designed to determine the clinicopathological determinants of the postoperative systemic inflammatory response following colorectal cancer resection. Methods: Patients with a histologically proven diagnosis of colorectal cancer who underwent elective, potentially curative resection during a period from 1999 to 2013 were included in the study (n = 752). Clinicopathological data and the postoperative SIR, as evidenced by postoperative Glasgow Prognostic Score (poGPS), were recorded in a prospectively maintained database. Results: The majority of patients were aged 65 years or older, male, were overweight or obese, and had an open resection. After adjustment for year of operation, a high day 3 poGPS was independently associated with American Society of Anesthesiologists (ASA) grade (hazard ratio [HR] 1.96; confidence interval [CI] 1.25–3.09; p = 0.003), body mass index (BMI) (HR 1.60; CI 1.07–2.38; p = 0.001), mGPS (HR 2.03; CI 1.35–3.03; p = 0.001), and tumour site (HR 2.99; CI 1.56–5.71; p < 0.001). After adjustment for year of operation, a high day 4 poGPS was independently associated with ASA grade (HR 1.65; CI 1.06–2.57; p = 0.028), mGPS (HR 1.81; CI 1.22–2.68; p = 0.003), NLR (HR 0.50; CI 0.26–0.95; p = 0.034), and tumour site (HR 2.90; CI 1.49–5.65; p = 0.002). Conclusions: ASA grade, BMI, mGPS, and tumour site were consistently associated with the magnitude of the postoperative systemic inflammatory response, evidenced by a high poGPS on days 3 and 4, in patients undergoing elective potentially curative resection for colorectal cancer

Evolution of Ultracold, Neutral Plasmas

We present the first large-scale simulations of an ultracold, neutral plasma, produced by photoionization of laser-cooled xenon atoms, from creation to initial expansion, using classical molecular dynamics methods with open boundary conditions. We reproduce many of the experimental findings such as the trapping efficiency of electrons with increased ion number, a minimum electron temperature achieved on approach to the photoionization threshold, and recombination into Rydberg states of anomalously-low principal quantum number. In addition, many of these effects establish themselves very early in the plasma evolution ($\sim$ ns) before present experimental observations begin.Comment: 4 pages, 3 figures, submitted to PR

Acute cell viability and nitric oxide release in lateral menisci following closed-joint knee injury in a lapine model of post-traumatic osteoarthritis

BACKGROUND: Traumatic impaction is known to cause acute cell death and macroscopic damage to cartilage and menisci in vitro. The purpose of this study was to investigate cell viability and macroscopic damage of the medial and lateral menisci using an in situ model of traumatic loading. Furthermore, the release of nitric oxide from meniscus, synovium, cartilage, and subchondral bone was also documented. METHODS: The left limbs of five rabbits were subjected to tibiofemoral impaction resulting in anterior cruciate ligament (ACL) rupture and meniscal damage. Meniscal tear morphology was assessed immediately after trauma and cell viability of the lateral and medial menisci was assessed 24 hrs post-injury. Nitric oxide (NO) released from joint tissues to the media was assayed at 12 and 24 hrs post injury. RESULTS: ACL and meniscal tearing resulted from the traumatic closed joint impact. A significant decrease in cell viability was observed in the lateral menisci following traumatic impaction compared to the medial menisci and control limbs. While NO release was greater in the impacted joints, this difference was not statistically significant. CONCLUSION: This is the first study to investigate acute meniscal viability following an in situ traumatic loading event that results in rupture of the ACL. The change in cell viability of the lateral menisci may play a role in the advancement of joint degeneration following traumatic knee joint injury. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2474-15-297) contains supplementary material, which is available to authorized users

The effects of auditory contrast tuning upon speech intelligibility

We have previously identified neurons tuned to spectral contrast of wideband sounds in auditory cortex of awake marmoset monkeys. Because additive noise alters the spectral contrast of speech, contrast-tuned neurons, if present in human auditory cortex, may aid in extracting speech from noise. Given that this cortical function may be underdeveloped in individuals with sensorineural hearing loss, incorporating biologically-inspired algorithms into external signal processing devices could provide speech enhancement benefits to cochlear implantees. In this study we first constructed a computational signal processing algorithm to mimic auditory cortex contrast tuning. We then manipulated the shape of contrast channels and evaluated the intelligibility of reconstructed noisy speech using a metric to predict cochlear implant user perception. Candidate speech enhancement strategies were then tested in cochlear implantees with a hearing-in-noise test. Accentuation of intermediate contrast values or all contrast values improved computed intelligibility. Cochlear implant subjects showed significant improvement in noisy speech intelligibility with a contrast shaping procedure

Plasma Oscillations and Expansion of an Ultracold Neutral Plasma

We report the observation of plasma oscillations in an ultracold neutral plasma. With this collective mode we probe the electron density distribution and study the expansion of the plasma as a function of time. For classical plasma conditions, i.e. weak Coulomb coupling, the expansion is dominated by the pressure of the electron gas and is described by a hydrodynamic model. Discrepancies between the model and observations at low temperature and high density may be due to strong coupling of the electrons.Comment: 4 pages, 4 figures. Accepted Phys. Rev. Let

Moat: A Virtual Private Network Appliance and Services Platform

Vakava onnettomuus, sairaus tai aivoinfarkti voi aiheuttaa tilan, jossa ihminen ei pysty liikkumaan eikä puhumaan. Usein kyky liikuttaa silmiä kuitenkin säilyy, vaikka ihminen olisi muuten täysin halvaantunut. Silmien liikettä ja katseen suuntaa voidaan tällöin hyödyntää kommunikaatiossa. Lääkäri voi esimerkiksi pyytää potilasta katsomaan ylös myöntymisen merkiksi. Vammautuneen henkilön eteen voidaan myös asettaa läpinäkyvä kommunikaatiotaulu, johon on kiinnitetty kuvia tai kirjaimia. Taulun avulla on mahdollista muodostaa sanoja ja lauseita katsomalla kirjaimia yksi kerrallaan. Keskustelukumppani tulkitsee viestin seuraamalla kommunikaatiotaulun toiselta puolelta henkilön katseen suuntaa. Kommunikaatiotaulua kehittyneempi menetelmä on katseenseurantalaite, joka mahdollistaa itsenäisen kirjoittamisen ja tietokoneen ohjaamisen katseella. Katseenseurantalaitteessa on tyypillisesti videokamera, joka kuvaa käyttäjän silmän liikkeitä. Tietokoneen ohjelma tulkitsee katseen suunnan ja päättelee, mihin kohtaan näytöllä käyttäjä kulloinkin katsoo. Yksinkertaisimmillaan näytöllä on kuva näppäimistöstä ja käyttäjä kirjoittaa silmillään katsomalla näppäimistön kirjaimia. Jotta tietokone erottaisi, milloin käyttäjä haluaa valita katsomansa kohteen, käyttäjän pitää katsoa kirjainta riittävän pitkään. Pitkä viive auttaa ehkäisemään virhevalintoja, mutta hidastaa samalla kommunikaatiota. Katseeseen perustuvia tekstinsyöttöjärjestelmiä on kehitetty muutaman vuosikymmenen ajan ja niiden käyttö kommunikaation apuvälineenä on yleistynyt viime vuosina. Katseella kirjoittamista ei kuitenkaan ole juurikaan tutkittu. Väitöskirja tarjoaa perusteellisen katsauksen aiheen tutkimukseen ja eri tapoihin käyttää katsetta tekstin tuottamiseen ja kommunikointiin. Työssä esitellään uusia tapoja tehostaa katseella kirjoittamista yksinkertaisten käyttöliittymäratkaisujen avulla. Väitöskirja tarjoaa tutkimustuloksiin perustuvia konkreettisia esimerkkejä ja ohjeita siitä, kuinka katseella kirjoittamisen miellyttävyyttä ja nopeutta voidaan parantaa huolellisen käyttöliittymäsuunnittelun avulla. Käyttäjätutkimukset osoittavat, että esimerkiksi ohjelman tarjoama palaute vaikuttaa merkittävästi kirjoitusnopeuteen ja virheiden määrään. Vastaavasti mahdollisuus säätää valintaan vaadittavaa viivettä mahdollistaa katsekirjoituksen nopean ja tehokkaan oppimisen.Text entry by eye gaze is used by people with severe motor disabilities. An eye tracking device follows the user s eye movements, and a computer program analyzes the gaze behavior. To type by gaze, the user typically points at the characters on an on-screen keyboard by looking at them and selects them by means of dwell time, a prolonged gaze that separates an intentional command from casual viewing. The basic methods for producing text by gaze have been researched and in real-world use since the early 1980s; however, the design issues have not been studied in detail. Until recently, assistive eye tracking systems were used mostly by a small number of people who were totally paralyzed and for whom gaze control was a necessity and the only option. The technology and its usability have improved considerably, and several new systems have appeared on the market, making the technology available for a much wider group of users with varying need and abilities. Today, the eye tracker can be considered an optional assistive device worth considering since it provides easy and fast access to information technology by gaze alone. This thesis provides an extensive review of the research conducted in the area of gaze-based text entry. It summarizes results from several experiments that study various aspects of text entry by gaze. Results show that small improvements in the interface design can lead to significant improvements in user performance and satisfaction. For example, adding a simple "click" that confirms the selection by gaze can significantly improve the text entry speed over that of plain visual feedback. The improvement is small, but the effect accumulates in the repetitive task of text entry. An overview of different design solutions and guidelines derived from the research results are given. It is hoped that the thesis will provide a useful starting point for developers, researchers, and assistive technology professionals wishing to gain deeper insight into gaze-based text entry