1,170 research outputs found

    Efficient discrete-time simulations of continuous-time quantum query algorithms

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    The continuous-time query model is a variant of the discrete query model in which queries can be interleaved with known operations (called "driving operations") continuously in time. Interesting algorithms have been discovered in this model, such as an algorithm for evaluating nand trees more efficiently than any classical algorithm. Subsequent work has shown that there also exists an efficient algorithm for nand trees in the discrete query model; however, there is no efficient conversion known for continuous-time query algorithms for arbitrary problems. We show that any quantum algorithm in the continuous-time query model whose total query time is T can be simulated by a quantum algorithm in the discrete query model that makes O[T log(T) / log(log(T))] queries. This is the first upper bound that is independent of the driving operations (i.e., it holds even if the norm of the driving Hamiltonian is very large). A corollary is that any lower bound of T queries for a problem in the discrete-time query model immediately carries over to a lower bound of \Omega[T log(log(T))/log (T)] in the continuous-time query model.Comment: 12 pages, 6 fig

    Plasma adrenomedullin is associated with short-term mortality and vasopressor requirement in patients admitted with sepsis

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    Introduction: The incidence of death among patients admitted for severe sepsis or septic shock is high. Adrenomedullin (ADM) plays a central role in initiating the hyperdynamic response during the early stages of sepsis. Pilot studies indicate an association of plasma ADM with the severity of the disease. In the present study we utilized a novel sandwich immunoassay of bioactive plasma ADM in patients hospitalized with sepsis in order to assess the clinical utility.Methods: We enrolled 101 consecutive patients admitted to the emergency department with suspected sepsis in this study. Sepsis was defined by fulfillment of at least two systemic inflammatory response syndrome (SIRS) criteria plus clinical suspicion of infection. Plasma samples for ADM measurement were obtained on admission and for the next four days. The 28-day mortality rate was recorded.Results: ADM at admission was associated with severity of disease (correlation with Acute Physiology and Chronic Health Evaluation II (APACHE II) score: r = 0.46; P <0.0001). ADM was also associated with 28-day mortality (ADM median (IQR): survivors: 50 (31 to 77) pg/mL; non-survivors: 84 (48 to 232) pg/mL; P <0.001) and was independent from and additive to APACHE II (P = 0.02). Cox regression analysis revealed an additive value of serial measurement of ADM over baseline assessment for prediction of 28-day mortality (P < 0.01). ADM was negatively correlated with mean arterial pressure (r = -0.39; P <0.0001), and it strongly discriminated those patients requiring vasopressor therapy from the others (ADM median (IQR): no vasopressors 48 (32 to 75) pg/mL; with vasopressors 129 (83 to 264) pg/mL, P <0.0001).Conclusions: In patients admitted with sepsis, severe sepsis or septic shock plasma ADM is strongly associated with severity of disease, vasopressor requirement and 28-day mortality

    Coverage of exposed hardware after lower leg fractures with free flaps or pedicled flaps

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    Abstract. – OBJECTIVE: The placement of osteosynthetic materials in the leg may be complicated by hardware exposure. Successful soft tissue reconstruction often provides a critical means for limb salvage in patients with hardware exposure in the leg. Free flaps are currently considered the standard surgical procedure for soft tissue coverage of the wounds with internal hardware exposure. However, to date, no conclusive literature shows the superiority of a specific type of flap. MATERIALS AND METHODS: The current review compares data from the literature concerning outcomes and complications of free and pedicled flaps for exposed osteosynthetic material preservation in the leg. RESULTS: A total of 81 cases from twelve different articles presenting internal hardware exposure of the leg were analyzed in our study. Thirty-two patients underwent immediate reconstructive surgery with pedicled flaps, while forty-nine patients underwent free flap reconstruction. The overall survival rate for pedicled flaps was 96.77%, while for free flaps it was 97.77%. The overall implant preservation rate was 78.12% for pedicled flaps and 53.33% for free flaps. With reference to postoperative complications, the overall complication rate was 46.87% for pedicled flaps and 10.20% for free flaps. CONCLUSIONS: No significant difference was found in terms of overall flap survival. However, a significant difference was found regarding successful implant preservation (78.12% in the pedicled flap group vs. 53.33% in the free flap group). In particular, the first observation appears to be in contrast with the current trend of considering the free flaps the first choice procedure for soft tissue coverage of the wounds with internal hardware exposure. Nevertheless, a higher occurrence of postoperative complications was observed in the pedicled flap group (46.87% vs. 10.20%). The choice of the most appropriate reconstructive procedure should take into account several issues including the size of the wounds with internal hardware exposure, the possibility of soft tissue coverage with pedicled flaps, the availability of recipient vessels, general conditions of the patients (such as age, diabetes, smoking history), patients’ preference and presence of a microsurgical team. However, according to the results of this review, we believe that pedicled flap reconstruction should be reconsidered as a valid alternative procedure for skin tissue loss with hardware exposure whenever it is possible

    Experimental method for measuring classical concurrence of generic beam shapes

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    Classical entanglement is a powerful tool which provides a neat numerical estimate for the study of classical correlations. Its experimental investigation, however, has been limited to special cases. Here, we demonstrate that the experimental quantification of the level of classical entanglement can be carried out in more general instances. Our approach enables the extension to arbitrarily shaped transverse modes and hence delivering a suitable quantification tool to describe concisely the modal structure

    The Status of Two Species of Nonindigenous Lizards in Florida, the Slender Chameleon, \u3ci\u3eChamaeleo gracilis\u3c/i\u3e Hallowell 1842 and White-lined Chameleon, \u3ci\u3eFurcifer lateralis\u3c/i\u3e (Gray 1831): A Corrigendum.

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    Krysko et al. (2016) recently published a summary of all known verified introductions of nonindigenous amphib­ians and reptiles in Florida, USA. Herein, we correct the iden­tity tity of one species and include an additional new record of a nonindigenous chameleon in Florida. Krysko et al. (2016) reported the presence of a White-lined Chameleon, Furcifer lateralis (Gray 1831). In fact, this was a misidentified Slender Chameleon, Chamaeleo gracilis Hallowell 1842 (C. Anderson, pers. comm. 2016). Discussion and reference to F. lateralis in Krysko et al. (2016) and all associated data (UF voucher number, locality, collector, and collection date, including Table 1, page 118, its associated paragraph, page 128, and the caption to Figure 10, page 128) should be modified to reflect this voucher’s identity as C. gracilis. Chamaeleo gracilis is indigenous to a broad region of eastern and western-central sub-Saharan Africa (Spawls et al. 2004; Tilbury and Tolley 2009; Tilbury 2014; Tolley and Menegan 2014; Glaw 2015). On 10 December 2004, a single supposed C. gracilis was found on a road in Palm City, Martin County, Florida. This gravid female oviposited 22 eggs in captivity, leading Engeman et al. (2005) to sug­gest that this species might be established. However, neither voucher specimen nor photograph was ever presented to con­firm the presence of this species, and no additional C. gracilis have since been found in that area

    Mpemba effect and phase transitions in the adiabatic cooling of water before freezing

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    An accurate experimental investigation on the Mpemba effect (that is, the freezing of initially hot water before cold one) is carried out, showing that in the adiabatic cooling of water a relevant role is played by supercooling as well as by phase transitions taking place at 6 +/- 1 oC, 3.5 +/- 0.5 oC and 1.3 +/- 0.6 oC, respectively. The last transition, occurring with a non negligible probability of 0.21, has not been detected earlier. Supported by the experimental results achieved, a thorough theoretical analysis of supercooling and such phase transitions, which are interpreted in terms of different ordering of clusters of molecules in water, is given.Comment: revtex, 4 pages, 2 figure

    Geographic distribution:\u3ci\u3e Acrantophis dumerili\u3c/i\u3e (Duméril’s Madagascan Ground Boa). USA. Florida.

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    The geographic distribution of Acrantophis dumerili, a nonindigenous introduced species in Florida, with new records, is presented. Acrantophis dumerili is indigenous to southern and southwestern Madagascar. We provide the first vouchers for Miami-Dade and Bay counties, which were likely escaped or released pets. Florida already has three established species of booid snakes (one boa, two pythons), all introduced through the pet trade pathway. Although there is no clear evidence for an established population of A. dumerili in Florida at this time, the Bay County individuals in a rural area in the Florida panhandle are a particular concern given that two propagules were found at the same general site less than one month apart, and Florida has the largest number of introduced herpetofauna in the world with nonindigenous species having a one out of three chance of becoming established (Krysko et al. 2016, op. cit.)

    Geographic distribution:\u3ci\u3e Acrantophis dumerili\u3c/i\u3e (Duméril’s Madagascan Ground Boa). USA. Florida.

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    The geographic distribution of Acrantophis dumerili, a nonindigenous introduced species in Florida, with new records, is presented. Acrantophis dumerili is indigenous to southern and southwestern Madagascar. We provide the first vouchers for Miami-Dade and Bay counties, which were likely escaped or released pets. Florida already has three established species of booid snakes (one boa, two pythons), all introduced through the pet trade pathway. Although there is no clear evidence for an established population of A. dumerili in Florida at this time, the Bay County individuals in a rural area in the Florida panhandle are a particular concern given that two propagules were found at the same general site less than one month apart, and Florida has the largest number of introduced herpetofauna in the world with nonindigenous species having a one out of three chance of becoming established (Krysko et al. 2016, op. cit.)

    Parameter Estimation with Mixed-State Quantum Computation

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    We present a quantum algorithm to estimate parameters at the quantum metrology limit using deterministic quantum computation with one bit. When the interactions occurring in a quantum system are described by a Hamiltonian H=θH0H= \theta H_0, we estimate θ\theta by zooming in on previous estimations and by implementing an adaptive Bayesian procedure. The final result of the algorithm is an updated estimation of θ\theta whose variance has been decreased in proportion to the time of evolution under H. For the problem of estimating several parameters, we implement dynamical-decoupling techniques and use the results of single parameter estimation. The cases of discrete-time evolution and reference-frame alignment are also discussed within the adaptive approach.Comment: 12 pages. Improved introduction and technical details moved to Appendi
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