Edge-emitting polariton laser and amplifier based on a ZnO waveguide

We demonstrate edge-emitting exciton-polariton (polariton) laser operation from 5 to 300 K and polariton amplifiers based on polariton modes within ZnO waveguides. The guided mode dispersion below and above the lasing threshold is directly measured using gratings placed on top of the sample, fully demonstrating the polaritonic nature of the lasing modes. The threshold is found to be smaller than that expected for radiative polaritons in planar ZnO microcavities below 150 K and comparable above. These results open up broad perspectives for guided polaritonics by enabling easier and more straightforward implementation of polariton integrated circuits that exploit fast propagating polaritons, and, possibly, topological protection.

Glassy Dynamics in a heavy ion irradiated NbSe2 crystal

Fascination with glassy states has persisted since Fisher introduced the vortex-glass as a new thermodynamic phase that is a true superconductor that lacks conventional long-range order. Though Fisher's original model considered point disorder, it was later predicted that columnar defects (CDs) could also induce glassiness - specifically, a Bose-glass phase. In YBa2Cu3O7-x (YBCO), glassy states can cause distinct behavior in the temperature (T ) dependent rate of thermally activated vortex motion (S). The vortex-glass state produces a plateau in S(T ) whereas a Bose-glass can transition into a state hosting vortex excitations called double-kinks that can expand, creating a large peak in S(T ). Although glass phases have been well-studied in YBCO, few studies exist of other materials containing CDs that could contribute to distinguishing universal behavior. Here, we report on the effectiveness of CDs tilted ~30° from the c-axis in reducing S in a NbSe2 crystal. The magnetization is 5 times higher and S is minimized when the field is parallel to the defects versus aligned with the c-axis. We see signatures of glassiness in both field orientations, but do not observe a peak in S(T ) nor a plateau at values observed in YBCO. Finally, we discuss the possibility that competing disorder induces a field-orientation-driven transition from a Bose-glass to an anisotropic glass involving both point and columnar disorder.

[Transcatheter aortic valve thrombosis]

GOALS

Transcatheter aortic valve or leaflets thrombosis are mainly misapprehended. It negatively impacts the long-term efficiency of such prosthesis. Moreover, its incidence is presumably higher than previously described.

EPIDEMIOLOGY

Recently reported subclinical leaflet thrombosis, occurring between first to third months after implantation, is about 10to 15%. All prosthesis are concerned by potential thrombosis.

DIAGNOSIS

Transcatheter aortic valve thrombosis is usually detected on the basis of increased transvalvular pressure gradients or symptoms at routine follow-up. Main causes of post-TAVI thrombosis are: elderly patients, incomplete TAVI expansion, incomplete TAVI apposition to the aortic wall, areas of diminished blood flow and stagnation around the prosthesis. Main risk-factors of thrombosis are: large valves, patients with ejection fraction lower than 35%, valve-in-valve implantation, males, patients with large sinus of Valsalva, patients without anticoagulants.

TREATMENT

Post-TAVI anti thrombotic regimen remains empirical. It is based on aspirin alone or dual antiplatelet therapy for 1-6months, followed by aspirin for life. Symptomatic patients with thrombus-based valve dysfunction are to be treated by oral anticoagulation (i.e., VKA or new oral anticoagulants NOAC). This treatment allows the restoration of normal leaflet motion in patients with a median time of 14 days.

Excitonic complexes in GaN/(Al,Ga)N quantum dots

Here we report a theoretical investigation of excitonic complexes in polar GaN/(Al,Ga)N quantum dots (QDs). A sum rule between the binding energies of charged excitons is used to calculate the biexciton binding energy. The binding energies of excitonic complexes in GaN/AlN are shown to be strongly correlated to the QD size. Due to the large hole localization, the positively charged exciton energy is found to be always blueshifted compared to the exciton one. The negatively charged exciton and the biexciton energy can be blueshifted or redshifted according to the QD size. Increasing the size of GaN/AlN QDs makes the identification of charged excitons difficult, and the use of an Al_0.5Ga_0.5N barrier can be advantageous for clear identification. Our theoretical results for the binding energy of exciton complexes are also confronted with values deduced experimentally for InAs/GaAs QDs, confirming our theoretical prediction for charged excitonic complexes in GaN/(Al,Ga)N QDs. Finally, we realize that the trends of excitonic complexes in QDs are significantly related to competition between the local charge separation (whatever its origin) and the correlation effect. Following our findings, entangled photons pairs can be produced in QDs with careful control of their size in order to obtain zero exciton-biexciton energy separation.

The effect and nature of N–H complexes in the control of the dominant photoluminescence transitions in UV-hydrogenated GaInNAs

A study of certain defects in GaInNAs, and their passivation. The passivation process could lead to more efficient photovoltaic devices.

[Myocardial ischaemia detection in women]

Screening of myocardial ischemia refers to the use of one or more diagnostic tests for coronary heart disease with a dual objective of appropriateness and promptness. In women, as compared to men, the accuracy of the different tests is worse. Thus, to overcome this sex-related penalty, we must define a diagnosis strategy based on risk stratification, enabling the identification of patients requiring invasive investigations. This review discusses various non-invasive diagnostic tests focusing on a female-specific approach and defines the use of numerous diagnostic tests with respect to both risk stratification and symptoms.

[Thromboaspiration in the treatment of ST segment elevation myocardial infarction]

Routine manual thrombectomy during primary percutaneous coronary intervention might be intuitively justified. While older registers reported contradictory results, interventional cardiologists remained interested in using such devices during the mechanical treatment of acute myocardial infarction. The first studies were congruent to demonstrate a significant relationship between thromboaspiration and significant improvement of ST-segment elevation, lower distal embolization, despite TAPAS was the only to significantly reduce the mortality. Later studies were unable to confirm these promising data, avoiding routine manual thrombectomy prior to primary angioplasty to decrease cardiovascular mortality, recurrent myocardial infarction, cardiogenic shock or severe heart failure. Moreover, thrombectomy was associated with an increased rate of stroke. Should thrombectomy therefore be conclusively overlooked? It is presumably required to define which patient is eligible for thrombectomy, to define how to perfectly perform manual thrombectomy, to specify how to gently move towards the thrombus, the optimal pharmacological environment, the number of aspirations and the criterion to stop or to repeat aspiration. Indeed, while thrombectomy is nowadays scientifically downgraded, it remains of potential interest in numerous interventional cardiologists.

Impact of hydroxychloroquine on preterm delivery and intrauterine growth restriction in pregnant women with systemic lupus erythematosus: a descriptive cohort study

OBJECTIVE

The aim of this study was to evaluate the effect of hydroxychloroquine (HCQ) on fetal preterm delivery and intrauterine growth restriction (IUGR) in a cohort of pregnant women with systemic lupus erythematosus (SLE).

METHODS

Over an 11-year period (January 1, 2001 to December 31, 2011), all women with SLE and admitted to deliver after 22 weeks of gestation to Bordeaux University Hospital (France), were retrospectively enrolled in the present study. The population was then split into two groups based on the treatment they received: HCQ exposed (HCQ+) versus HCQ non-exposed (HCQ-) group.

RESULTS

118 pregnancies were included, 41 in the HCQ+ group and 77 in the HCQ- group. The rate of adverse fetal outcome was significantly lower in the HCQ+ group (p = 0.001), particularly in terms of preterm delivery, 15.8% versus 44.2% (p = 0.006), and IUGR, 10.5% versus 28.6% (p = 0.03). No adverse outcomes were reported in the HCQ+ group.

CONCLUSION

HCQ reduces neonatal morbidity in women with SLE by significantly decreasing the rate of prematurity and intrauterine growth restriction.

Photoluminescence excitation spectroscopy of GaN thin layers as a function of temperature

We report on photoluminescence and photoluminescence excitation experiments performed on hexagonal GaN layers grown on a Sapphire substrate. Information about extrinsic and intrinsic optical properties have been obtained. We show that, at low temperature, the fundamental A excitons are preferentially involved in the relaxation towards the neutral donor bound exciton photoluminescence line, while electron-hole pairs rather participate in the relaxation towards D0−A0 emission and the yellow band. The relaxation from the A exciton towards the yellow band and D0−A0 emission is made easier by temperature. The band structure of the GaN layers has been determined from temperature dependent photoluminescence excitation spectroscopy: A and C excitons and A continuum band gap have been identified up to 210K.

Analysis of the Visible and UV Electroluminescence in Homojunction GaN LED's

The electrical and electroluminescent properties of MOVPE GaN p-n homojunctions have been analyzed as a function of temperature and bias. Electroluminescence is observed for V>3 V under dc and ac conditions. The main emission at low T is a donor-acceptor transition involving shallow acceptors, though it disappears at higher T due to the ionization of the acceptors and compensation by ionized donors. Room temperature dc and ac electroluminescence spectra evolve under increasing bias from a blue-shifting visible band involving deep states at the p-type side of the p-n junction, to a band-to-band UV recombination at high bias. In agreement, the superlinear dependence of light-current characteristics at low current injection becomes linear when the defects are saturated. Time analysis of the spectra vs pulse duration and duty cycle allows the determination of the visible radiative recombination and relaxation times associated to the Mg-related deep states, which are found to behave as acceptors lying 0.55 eV above the valence band. A simple 3-level model is able to explain the visible emission, which involves the conduction band (or shallow donor) and those deep acceptors in the p-layer. Optimum UV/visible ratio emission requires intense and relatively long pulses, with a high duty cycle to impede visible recombination.

p-doping of GaN by MOVPE

Mg has been widely used as p-doping species despite its intrinsic difficulties. It is nowadays well established that during the growth process of Mg doped GaN, atomic H is generated from the decomposition of NH3 and Mg-H complexes are formed in the layer. This has been for instance shown by the occurrence of LO mode in IR absorption, and by the observation of the Mg-H local vibration modes. This H passivation limits the electrical activity of Mg, therefore an activation process is required to get full activation of the Mg atoms. In the present study, bismethylcyclopentadienyl magnesium [(MeCp)2Mg] was used as precursor. However, this precursor reacts in the gas phase with NH3 to produce tiny solid particles as evidenced by a very bright diffuse emission visible along the laser beam used for reflectometry measurements. This simplest obvious product would be [(MeCp)Mg(NH2)]m(m≥2). To limit this drawback, Ga and Mg precursor lines have been separated. With proper in situ heat treatment, doping densities up to 1.5×1018 cm−3 have been obtained. PL spectra of lightly Mg doped samples (1016 cm−3) are dominated by shallow donor-acceptor pairs whereas for higher doping densities ( 1018 cm−3), the luminescence is dominated by a broad band in the 2.7-2.9 eV range. GaN LEDs were fabricated from Si doped (n-type) and Mg-doped (p-type) GaN, these LEDs emit in the blue-UV range.

Temperature behaviour of the yellow emission in GaN

Even in good quality undoped GaN samples, as assessed by the intense excitonic emission, the yellow band is present. This band has been attributed either to a shallow donor to deep double donor pair recombination [1], to a deep donor to a shallow acceptor [2] or to a shallow donor and a deep state [3]. However, its origin is not yet clear. We present data on time resolved spectroscopy compared with steady state results. These results indicate that there is no difference in band shape between steady state and time resolved spectra at all temperatures. However, in some samples there is an increase in intensity of the yellow band. It is concluded that besides a fast emission, due to prompt excitation of the centre, an indirect path from a trap 13.7 meV below the shallow donor is responsible for the long component of the decay and the intensity increase. An emission with a lifetime of ca. 300 ms is also present with a maximum at 2.35 eV.

Luminescence and Reflectivity of GaN/sapphire grown by MOVPE, GSMBE and HVPE

This work presents an optical characterization by luminescence and reflectivity of GaN layers grown on sapphire using MOVPE, HVPE and GSMBE. Well resolved optical spectra are obtained for each growth technique. The luminescence of Mg doped MOVPE grown GaN is also studied. A Mg acceptor optical depth of ~ 260 meV is obtained.

Mammalian exocrine secretions: IX. Constituents of preorbital secretion of oribi,Ourebia, ourebi

Using gas chromatography-mass spectrometry in conjunction with ancillary techniques such as chemical ionization with different reactant gases, determination of the position of double bonds by means of dimethyl disulfide derivatization, and finally gas chromatographic and mass spectrometric comparison with authentic synthetic material, 75 constituents were identified in the preorbital secretion of the male oribi,Ourebia ourebi. The secretion contains compounds with long-chain, unbranched structures similar to those found in many other preorbital secretions but with a finite volatility range, in contrast to the seemingly endlessly increasing chain lengths typical of other preorbital secretions.

From excitonic to photonic polariton condensate in a ZnO-based microcavity

We report exciton-polariton condensation in a new family of fully hybrid ZnO-based microcavity demonstrating the best-quality ZnO material available (a bulk substrate), a large quality factor (~4000) and large Rabi splittings (~240 meV). Condensation is achieved between 4 and 300 K and for excitonic fractions ranging between 17% and 96%, which corresponds to a tuning of the exciton-polariton mass, lifetime, and interaction constant by 1 order of magnitude. We demonstrate mode switching between polariton branches allowing, just by controlling the pumping power, to tune the photonic fraction by a factor of 4.

High quality factor nitride-based optical cavities: microdisks with embedded GaN/Al(Ga)N quantum dots

We compare the quality factor values of the whispering gallery modes of microdisks (μ-disks) incorporating GaN quantum dots (QDs) grown on AlN and AlGaN barriers by performing room temperature photoluminescence (PL) spectroscopy. The PL measurements show a large number of high Q factor resonant modes on the whole spectrum, which allows us to identify the different radial mode families and to compare them with simulations. We report a considerable improvement of the Q factor, which reflects the etching quality and the relatively low cavity loss by inserting QDs into the cavity. GaN/AlN QDs-based μ-disks show very high Q values (Q>7000) whereas the Q factor is only up to 2000 in μ-disks embedding QDs grown on the AlGaN barrier layer. We attribute this difference to the lower absorption below bandgap for AlN barrier layers at the energies of our experimental investigation.

Tunnel radiation in the luminescence spectra of GaN-based heterostructures

Tunnel effects in luminescence spectra and electrical properties of LEDs based on InGaN/GaN-heterostructures made by different technological groups were studied. The tunnel radiation in a spectral region of 1.9 - 2.7 eV predominates at low currents (J<0.2 mA). The position of the tunnel luminescence maximum orħħωmax is approximately equal to the voltage U, orħħωmax = eU. The low energy spectral band is described by the theory of tunnel radiative recombination. Tunnel recombination mechanisms in GaN-based heterostructures are caused by high electric fields in the active InGaN/GaN - MQW layers. The energy diagram of the structures is analyzed. The probability of tunnel radiation is higher due to piezoelectric fields in InGaN quantum wells. The tunnel radiation spectral band was not observed in the more effective LEDs with modulated doped MQWs. The spectra of GaN-based LEDs are compared with tunnel radiation spectra of GaAs-, InP- and GaSb- based LEDs. The equation: orħħωmax = eU describes experimental data in various semiconductors in the range 0.5–2.7 eV.

Characterization of Near-Edge-Optical Transitions in Undoped and Doped GaN/Sapphire Grown by MOVPE, HVPE, and GSMBE

We report a comparative study by luminescence and reflectivity of GaN grown on sapphire by MOVPE, HVPE and GSMBE. Whatever the growth technique, undoped GaN shows well resolved reflectivity spectra, allowing hetero-epitaxial strain to be taken into account in the interpretation of luminescence spectra. MOVPE provides the highest purity samples so far. From the luminescence study of n- and p-type doped samples, activation energies of 265 ± 10 meV and 34 ± 2 meV are deduced for Mg acceptors and Si donors respectively. From the luminescence spectra of HVPE grown samples, the presence of a perturbed interfacial n+ layer is evidenced.

Filtering of Defects in Semipolar (11-22) GaN Using 2-Steps Lateral Epitaxial Overgrowth

Good-quality (11-22) semipolar GaN sample was obtained using epitaxial lateral overgrowth. The growth conditions were chosen to enhance the growth rate along the [0001] inclined direction. Thus, the coalescence boundaries stop the propagation of basal stacking faults. The faults filtering and the improvement of the crystalline quality were attested by transmission electron microscopy and low temperature photoluminescence. The temperature dependence of the luminescence polarization under normal incidence was also studied.

Phase II trial of erlotinib in advanced pancreatic cancer (PC)

4609

Background: The epidermal growth factor receptor (EGFR) is a potentially important target in PC. Benefit from erlotinib (Tarceva), an oral EGFR tyrosine kinase inhibitor has been associated with the presence of a skin rash. The purpose of this study was to determine the efficacy of erlotinib, dosed to achieve a rash, in patients (pts) with PC. Methods: Erlotinib was given at an initial dose of 150 mg/day to eligible pts with locally advanced (LA) or metastatic PC who had progressed or were unable to tolerate gemcitabine-based chemotherapy. The dose of erlotinib was increased by 50mg every 2 weeks (maximum 300 mg/day) until > grade 1 rash (CTCAE v 3.0) or other dose-limiting toxicities occurred. Erlotinib pharmacokinetic (PK) studies were performed. Baseline tumor tissue was collected for analysis of Kras mutations, EGFR by IHC and FISH. The primary endpoint of this two- stage phase II trial was prolonged disease control (PR + SD > 8 wks) with a rate of >20% assumed to be significant . Results: Fifty pts were accrued (median age 61, M:F = 25:25, ECOG 0:1:2 = 5:41:4, LA:Metastatic = 5:45, prior gemcitabine none:adjuvant:palliative = 2:16:35). 47 and 40 pts were evaluable for toxicity and response, respectively. Dose-escalation to 200–300 mg of erlotinib was possible in 9 pts. Most common treatment adverse events (TAEs) of any grade were: rash (35 pts, 74.5%), diarrhea (18 pts, 38.3 %), and fatigue (8 pts, 17%). Grade 3+ TAEs were rash in 2 pts and diarrhea in 2 pts. Best response was SD in 14 pts, 0.35 (95% CI: 0.2–0.5). Prolonged disease control (SD > 8 wks) was observed in 10/40 evaluable pts, 0.25 (95% CI: 0.12–0.38), which met the primary study endpoint. Median TTP was 1.6 mo (95% CI:1.6–2.1), mOS 4.1 mo (95% CI:3.2–7.3), and 6 mo OS rate was 39% (95%CI: 24–61%). PK and correlative data are being analyzed and will be presented. Conclusions: Erlotinib is associated with prolonged stable disease in a subset of pts with advanced refractory PC. Dose escalation in the absence of toxicity is feasible and safe.

[Table: see text]

Efficacy of cabergoline in restless legs syndrome: A placebo-controlled study with polysomnography (CATOR)

OBJECTIVE

To assess the efficacy and safety of the dopamine agonist cabergoline in the treatment of patients with idiopathic restless legs syndrome (CATOR study).

METHODS

Patients with moderate to severe restless legs syndrome (RLS) were randomly assigned to cabergoline (single evening dose: 2 mg) or placebo and treated for 5 weeks in a double-blind, multicenter polysomnography (PSG) trial. The primary efficacy measures were the periodic leg movements during sleep arousal index (PLMS-AI) and sleep efficiency. These and further PSG variables were monitored by centrally evaluated PSG. Severity of RLS was assessed using the International RLS Study Group Severity Scale (IRLS), the RLS-6 scales, the Sleep Questionnaire Form A (SF-A; quality of sleep), and the Quality of Life for RLS questionnaire.

RESULTS

Forty-three patients were treated and 40 patients were evaluated with PSG (age 56 +/- 10 years, 73% women). Cabergoline was superior to placebo in terms of the PLMS-AI (-17.7 +/- 16.4 vs -4.5 +/- 20.0 placebo; p = 0.0024), sleep efficiency (+6.2 +/- 13.9% vs +3.3 +/- 11.7%; p = 0.0443), PLMS index (p = 0.0014), PLM index (p = 0.0012), and total sleep time (p = 0.0443). Improvements in IRLS total score (-23.7 +/- 11.2 vs -7.9 +/- 11.0 placebo; p = 0.0002), RLS-6 severity scales during the night (p = 0.0010) and during the day (p = 0.0018), Clinical Global Impressions severity item (p = 0.0003), sleep quality (p = 0.0180), SF-A sleep quality (p = 0.0371), and QoL-RLS (p = 0.0247) were larger in patients treated with cabergoline compared with the placebo group. Adverse events were only mild and well-known side effects of dopamine agonists.

CONCLUSION

Single-evening cabergoline is an efficacious and well-tolerated short-term therapy for sensorimotor symptoms of restless legs syndrome and associated sleep disturbances.

Effective cabergoline treatment in idiopathic restless legs syndrome

OBJECTIVE

To assess the efficacy and safety of the dopamine agonist cabergoline (CAB) in patients with restless legs syndrome (RLS).

METHODS

Patients with moderate to severe RLS were randomized into four groups receiving placebo, 0.5 mg, 1 mg, or 2 mg CAB once daily in a double-blind, placebo-controlled, multicenter dose-finding trial followed by an open long-term extension trial of 47 weeks. Efficacy was assessed with the RLS-6 scales and International RLS Study Group severity scale (IRLS).

RESULTS

A total of 85 patients (age 56 +/- 10 years, 71% females) were treated. Severity of RLS-6 scale symptoms during the night (the primary endpoint) was markedly improved by all CAB doses compared to placebo (placebo: -1.4 +/- 3.1, 0.5 mg CAB: -4.2 +/- 3.0 [p = 0.0082], 1.0 mg CAB: -4.0 +/- 2.9 [p = 0.0040], 2.0 mg CAB: -4.8 +/- 3.7 [p = 0.0026]). Similar results were found for the RLS severity at bedtime and during the day, IRLS, and satisfaction with sleep. A stable, clinically relevant improvement was achieved in all efficacy measures (severity during the night: change between last assessment and baseline: -5.6 +/- 2.5, rate of remission: 71.2%) throughout 1 year with a mean CAB dose of 2.2 mg per day. During long-term treatment, 6 of 66 treated patients were affected (n = 2) or possibly affected (n = 4) by mild augmentation. Under CAB therapy up to 1 year, 11 of 85 patients discontinued treatment due to a drug-related adverse event.

CONCLUSIONS

Cabergoline is an efficacious and well-tolerated option for the treatment of restless legs symptoms during the night and the day.

Simplified models of flue instruments: influence of mouth geometry on the sound source

Flue instruments such as the recorder flute and the transverse flute have different mouth geometries and acoustical response. The effect of the mouth geometry is studied by considering the aeroacoustical response of a simple whistle. The labium of a transverse flute has a large edge angle (60 degrees) compared to that of a recorder flute (15 degrees). Furthermore, the ratio W/h of the mouth width W to the jet thickness h can be varied in the transverse flute (lips of the musician) while it is fixed to a value W/h approximately 4 in a recorder flute. A systematic experimental study of the steady oscillation behavior has been carried out. Results of acoustical pressure measurements and flow visualization are presented. The sharp edge of the recorder provides a sound source which is rich in harmonics at the cost of stability. The larger angle of the labium of the flute seems to be motivated by a better stability of the oscillations for thick jets but could also be motivated by a reduction of broadband turbulence noise. We propose two simplified sound source models which could be used for sound synthesis: a jet-drive model for W/h>2 and a discrete-vortex model for W/h<2.

Multicenter evaluation of the Glucometer Elite XL meter, an instrument specifically designed for use with neonates

OBJECTIVE

To evaluate the clinical performance of the Glucometer Elite XL Diabetes Care System in neonatal settings using a multicenter study

RESEARCH DESIGN AND METHODS

A total of 388 blood specimens from 333 neonates were included in the study. A capillary or arterial sample was analyzed for determination of glucose with the Glucometer Elite XL system by an attending trained nurse. Through the same sampling site, a specimen was collected and sent to the laboratory for measurement of plasma glucose, bilirubin, and hematocrit.

RESULTS

The regression analysis between the results of the Glucometer Elite XL system and comparative methods resulted in the following: Glucometer Elite XL meter = 1.01 x laboratory method + 0.02 mmol/l (n = 388). For the 1.1-4.0 mmol/l plasma glucose range, the regression was Glucometer Elite XL meter = 1.07 x laboratory method + 0.12 mmol/l (n = 150). A difference plot indicated a mean bias of 0.04 mmol/l (95% CI -0.01 to 0.10). No relationship was found between meter glucose biases and hematocrit levels (r = 0.10, P = 0.14). Although a statistically significant correlation existed between bilirubin levels and the glucose meter biases (r = 0.14, P = 0.005), the predicted mean biases were of little clinical significance.

CONCLUSIONS

The Glucometer Elite XL system showed a good performance when used in neonatal settings.

Effect of point of care testing on length of stay in an adult emergency department

Devices are now available that are practical for point of care testing (PCT) in hospital settings. Previous studies in clinical settings, however, have failed to demonstrate a reduction in patients' length of stay (LOS) associated with the use of PCT. This randomized controlled study compared PCT with central laboratory testing in a hospital Emergency Department to assess the difference in patients' LOS. Patients randomized to PCT (n = 93) had a median stay of 3 h, 28 min (interquartile range [IR] 2:28 to 5:30), while those allocated to the central laboratory (n = 87) had a median stay of 4 h, 22 min (IR 3:04 to 5:47). The median stay associated with PCT was significantly shorter. Among patients who were destined to be discharged home, there was also a significantly shorter stay, but not among those who were destined to be admitted. It was concluded that the use of PCT can achieve significant time savings in an Emergency Department.

[An anatomic study of the superficial radial nerve and its clinical implications]

In hand surgery, the k-wires are used frequently and effectively. Several texts mention complications following surgery of the wrist and hand. A safe zone has been described by Steinberg et al., where 40 K-wires were placed in the anatomic snuffbox of 10 cadaveric forearms. The placement of the k-wires were evaluated radiologically and by dissection to examine the underlying structures. A branch of the superficial radial nerve (NRS) was injured in 22% (2/9) of the specimens and the cephalic vein in 33% (3/9). The radial artery was never injured but had a K-wires at least 1 mm away in 22% of the specimens. The anatomy and pattern of distribution of the NRS was studied and compared with the data found in the literature. The NRS emerged between the tendons the muscles of brachioradialis and extensor carpi radialis longus in 9 of 10 specimens, and at a mean distance of 7.8 cm from the radial styloid. The first and second division were at a mean distance proximal to the radial styloid of 4.5 and 3.0 cm, respectively. The mean number of branches of the NRS at the radial styloid was 5.1. Despite a relatively consistent anatomy of the NRS, the anatomic snuffbox remains a complex and dangerous area due to the variability of the nerve's anatomy. An open surgical approach is thus preferred to avoid traumatizing the nerves and vascular structures.

[Biomechanical evaluation and clinical correlation of 3 methods of internal fixation of metacarpophalangeal arthrodesis of the thumb]

Three methods of internal fixation for MCP arthrodesis of fifteen cadaveric thumbs were used to analyze the biomechanical stability by applying a palmar force, lateral force, and torsion moment. The techniques used included two K-wires 0.045 in parallel (BK), 2 cerclage metallic wires #25 perpendicular to each other (CP), and a 6-holes plate and screws construct from Synthes (PV). The initial rigidity was measured using a Bionix MTS-858. The results after statistical analysis showed: 1) CP was just as rigid as PV for the palmar and lateral tests; 2) CP was, overall, superior to BK in palmar and lateral tests; 3) no difference existed in torsion between the three types of fixation. A comparison was done between the rigidity of the fixation techniques used and the rates of bony nonunion found in the literature. The mean rates of nonunion were reported to be 0-4.0% for the following techniques: CP, tension band wiring (TB), plate and screws, external fixation, compression screw. The rates of nonunion were higher, 7.5-12.5%, for BK, cerclages not perpendicular (CM), bone pegs. According to the results of this biomechanical study and the review of the literature, fixation with BK is the least rigid, and fixation with CP is just as rigid as with PV. The success clinically of CP is yet to be demonstrated. Other studies on the properties of CP for fatigue would be necessary to give a better analysis.

Multianalyte serum analysis using mid-infrared spectroscopy

This study assesses the potential for using mid-infrared (mid-IR) spectroscopy of dried serum films as the basis for the simultaneous quantitation of eight serum analytes: total protein, albumin, triglycerides, cholesterol, glucose, urea, creatinine and uric acid. Infrared transmission spectra were acquired for 300 serum samples, each analysed independently using accepted reference clinical chemical methods. Quantitation methods were based upon the infrared spectra and reference analyses for 200 specimens, and the models validated using the remaining 100 samples. Standard errors in the IR-predicted analyte levels (Sy/x) were 2.8 g/L (total protein), 2.2 g/L (albumin), 0.23 mmol/L (triglycerides), 0.28 mmol/L (cholesterol), 0.41 mmol/L (glucose) and 1.1 mmol/L for urea, with correlation coefficients (IR vs reference analyses) of 0.95 or better. The IR method emerged to be less suited for creatinine (Sy/x = mumol/L) and uric acid (Sy/x = 140 mumol/L) due to the relatively low concentrations typical of these analytes.

Three-dimensional joint moments analysis in a vertical quadrupedal posture associated with a leg release

This study reports on rock climbers biomechanical adjustments following a leg release from a quadrupedal vertical initial stance. Six climbers of international level have been studied. They were asked to maintain a quadrupedal posture on artificial holds equipped with strain gauges and then to release their right foot. The results show that all the rock climbers adjust differently the vertical forces and the horizontal forces on the holds. They distribute the vertical forces over the three remaining holds and the horizontal forces over the controlateral holds. A quasi-static three-dimensional multi-segment model was used to produce the net reaction forces and joint moments at each joint. Moment results enhance the role of the controlateral limbs, particularly the left leg. The gravity seems to be counteracted at the left knee joint, while body balance seems to be managed at the left hip and ankle joints.

Quantitation of protein, creatinine, and urea in urine by near-infrared spectroscopy

OBJECTIVES

To determine the feasibility of near-infrared analysis for quantitating urea, creatinine, and protein in urine. Practical advantages of this method include ease of sample presentation and the absence of reagents or disposables.

DESIGN AND METHODS

The near-infrared methods were developed by first measuring the spectra of 123 different urine samples and, using independent clinical analyses, determining the protein, creatinine, and urea levels in each. Calibration models relating near-infrared spectroscopic features to those independently determined concentrations were optimized, and each model then validated using a set of 50 additional samples.

RESULTS

Standard errors of calibration were 14.4 mmol/L, 0.66 mmol/L, and 0.20 g/L, and standard errors of prediction 16.6 mmol/L, 0.79 mmol/L, and 0.23 g/L, respectively, for urea, creatinine, and protein.

CONCLUSIONS

Near-infrared urea quantitation is as accurate as the reference method, enzymatic (urease) conductivity, used here for calibration. Creatinine analysis is slightly less accurate relative to the reference (Jaffe rate) method; however, these errors can be minimized by careful attention to factors affecting precision. The accuracy of the near-infrared protein analysis cannot approach that of the reference method; nevertheless, the technique is potentially useful for coarse screening and for quantifying protein levels above 0.3 g/L.

Effect of initial posture on biomechanical adjustments associated with a voluntary leg movement in rock climbers

This study compares the biomechanical adjustments following a leg displacement in vertical and horizontal position on expert rock climbers. The results show a non-diagonal pattern in the vertical condition and a diagonal one in the horizontal condition. A multi-link analysis shows that the non-diagonal pattern displayed by expert climbers in the vertical condition resulted in a new distribution of body weight to preserve the possibility of moving any limb from the three legged stance. Conversely, in the horizontal condition, the diagonal pattern appears to be strongly dominated by mechanical and anthropometric factors.