699 research outputs found
New spectral functions of the near-ground albedo derived from aircraft diffraction spectrometer observations
No full textThe airborne spectral observations of the upward and downward irradiances are
revisited to investigate the dependence of the near-ground albedo as a
function of wavelength in the entire solar spectrum for different surfaces
(sand, water, snow) and under different conditions (clear or cloudy sky). The
radiative upward and downward fluxes were determined by a diffraction
spectrometer flown on a research aircraft that was performing multiple flight
paths near the ground. The results obtained show that the near-ground albedo
does not generally increase with increasing wavelengths for all kinds of
surfaces as is widely believed today. Particularly, in the case of water
surfaces it was found that the albedo in the ultraviolet region is more or
less independent of the wavelength on a long-term basis. Interestingly, in
the visible and near-infrared spectra the water albedo obeys an almost
constant power-law relationship with wavelength. In the case of sand surfaces
it was found that the sand albedo is a quadratic function of wavelength,
which becomes more accurate if the ultraviolet wavelengths are neglected.
Finally, it was found that the spectral dependence of snow albedo behaves
similarly to that of water, i.e. both decrease from the ultraviolet to the
near-infrared wavelengths by 20–50%, despite the fact that their values
differ by one order of magnitude (water albedo being lower). In addition, the
snow albedo vs. ultraviolet wavelength is almost constant, while in the
visible near-infrared spectrum the best simulation is achieved by a
second-order polynomial, as in the case of sand, but with opposite slopes
Peeling-ballooning stability of tokamak plasmas with applied 3D magnetic fields
No full textThe poloidal harmonics of the toroidal normal modes of an unstable axisymmetric tokamak plasma are employed as basis functions for the minimisation of the 3D energy functional. This approach presents a natural extension of the perturbative method considered in Anastopoulos Tzanis et al (2019 Nucl. Fusion 59 126028). This variational formulation is applied to the stability of tokamak plasmas subject to external non-axisymmetric magnetic fields. A comparison of the variational and perturbative methods shows that for D-shaped, high β N plasmas, the coupling of normal modes becomes strong at experimentally relevant applied 3D fields, leading to violation of the assumptions that justify a perturbative analysis. The variational analysis employed here addresses strong coupling, minimising energy with respect to both toroidal and poloidal Fourier coefficients. In general, it is observed that ballooning unstable modes are further destabilised by the applied 3D fields and field-aligned localisation of the perturbation takes place, as local ballooning theory suggests. For D-shaped high β N plasmas, relevant to experimental cases, it is observed that the existence of intermediate n unstable peeling-ballooning modes, where a maximum in the growth rate spectrum typically occurs, leads to a destabilising synergistic coupling that strongly degrades the stability of the 3D system
Exniphargus tzanisi Karaman G. S. 2016
No full text<i>Exniphargus tzanisi</i> Karaman G.S., 2016 <p> <b>Published records:</b> Karaman G.S. (2016b).</p> <p> <b>Distribution:</b> Endemic to <b>Greece</b>: Crete Island (KR).</p> <p> <b>Type material:</b> Holotype: male 8.5 mm, Tzanis spilios Cave, Lefka Ori Massif, W part of Crete Island, September, 1988, 5 exp. (leg. B. Sket). Paratype: female 8.1 mm, data same as for the holotype. Holotype and paratype are deposited in KCPM.</p> <p> <b>Remarks:</b> The phylogenetic position of <i>E. tzanisi</i> has not been yet studied using molecular methods, and the validity of the genus has to be confirmed.</p> <p> <b>Etymology</b>: The specific epythet “tzanisi” was named after the type locality, Tzanis Cave on Crete Island.</p>Published as part of <i>Ntakis, Alexandros, Karaouzas, Ioannis, Fišer, Cene & Stoch, Fabio, 2020, An annotated checklist of the Niphargidae (Crustacea: Amphipoda) of Greece, pp. 517-544 in Zootaxa 4772 (3)</i> on page 518, DOI: 10.11646/zootaxa.4772.3.5, <a href="http://zenodo.org/record/3856611">http://zenodo.org/record/3856611</a>
Temporal trends in procedural death and need for urgent open surgery during transcatheter aortic valve replacement: A single, high-volume center 10-year experience
No full textBACKGROUND: Despite advancements in the safety of transcatheter aortic valve replacement (TAVR) resulting in progressively wider indications, adverse periprocedural outcomes still raise concern. Real-world outcome data are thus of primary importance to evaluate the procedural risk-benefit trade-off in the continuously changing populations undergoing TAVR.METHODS: We retrospectively assessed 1348 consecutive patients undergoing TAVR between 2007 and 2017. The primary endpoint was a composite of procedural mortality and need for conversion to emergent surgery, as defined by the Valve Academic Research Consortium-2 criteria. Temporal trends in baseline characteristics and outcomes were evaluated. The independent outcomes predictors were assessed through multivariate regression analysis.RESULTS: A total of 56 (4.1%) patients experienced the primary endpoint. 47 (3.5%) patients died during hospital stay, 19 (1.4%) within 72 h from the procedure. 17 patients (1.2%) needed an emergent conversion to open surgery, of whom 7 (41.2%) did not survive. Significant temporal trends of increasing mean age (from 79.4 ± 7.4 to 81 ± 7.5, p = 0.007) and decreasing surgical risk (mean STS: from 9 ± 9.5 to 7.1 ± 9.8, p = 0.010) were observed. When dichotomized at the median procedural date (year 2014), a significant reduction in the occurrence of the primary endpoint in more recent years was observed (3.0% vs 5.2%, p = 0.041). This was the single primary endpoint independent predictor at multivariate analysis.CONCLUSION: The high-volume 10-year experience in TAVR procedures at our center shows encouraging trends in procedural mortality reduction, which anyhow still occurs at a non-negligible rate, calling for further research to detect and to blunt the determinant of early procedural events
Maximum inspiratory pressure, a surrogate parameter for the assessment of ICU-acquired weakness
No full textBackground: Physical examination has been advocated as a primary determinant of ICU-acquired weakness (ICU-AW). The purpose of the study is to investigate ICU-AW development by using Maximum Inspiratory Pressure (MIP) as a surrogate parameter of the standardized method to evaluate patients' peripheral muscle strength.Methods: Seventy-four patients were recruited in the study and prospectively evaluated in a multidisciplinary university ICU towards the appearance of ICU-AW. APACHE II admission score was 16 ± 6 and ICU stay 26 ± 18 days. ICU-AW was diagnosed with the Medical Research Council (MRC) scale for the clinical evaluation of muscle strength. MIP was measured using the unidirectional valve method, independently of the patients' ability to cooperate.Results: A significant correlation was found between MIP and MRC (r = 0.68, p &lt; 0.001). Patients that developed ICU-AW (MRC&lt;48) had a longer weaning period compared to non ICU-AW patients (12 ± 14 versus 2 ± 3 days, p &lt; 0.01). A cut-off point of 36 cmH2O for MIP was defined by ROC curve analysis for ICU-AW diagnosis (88% sensitivity,76% specificity). Patients with MIP below the cut-off point of 36 cmH2O had a significant greater weaning period (10 ± 14 versus 3 ± 3 days, p = 0.004) also shown by Kaplan-Meier analysis (log-rank:8.2;p = 0.004).Conclusions: MIP estimated using the unidirectional valve method may be a potential surrogate parameter for the assessment of muscle strength compromise, useful for the early detection of ICU-AW. © 2011 Tzanis et al; licensee BioMed Central Ltd
Efficacy of Coronary Sinus Reducer in Patients With Non-revascularized Chronic Total Occlusions
No full textThe coronary sinus reducer (CSR) has been introduced as therapy for patients with refractory angina with no other treatment options. Aim of this study is to investigate the efficacy of the CSR in patients with refractory angina and presence of coronary chronic total occlusions (CTO). In this multicentre, international retrospective study, patients undergoing CSR implantation were screened and divided in 2 groups according to the presence/absence of CTO lesions. Baseline and clinical characteristics were analyzed in the 2 groups. Primary-outcome consisted of the variation in Canadian Cardiovascular Society (CCS) class at 6-month follow-up. Between January 2014 and December 2018, 205 patients with refractory angina were consecutively treated with the study device in the participating centers, 103 (50.2%) of which had a CTO lesion at coronary angiogram and formed the CTO-group. Baseline characteristics of the study population were well balanced between the 2 groups. CSR was successfully implanted in all cases. Baseline CCS class was 3 ± 0.5 in the CTO-group versus 3.1 ± 0.6 in the non-CTO group (p = 0.45), and improved at follow-up to 1.6 ± 0.9 versus 2 ± 1.1 respectively (p <0.01), with a significantly higher improvement in CCS class in the CTO-group (1.4 ± 0.9 vs 1.1 ± 1 respectively, p = 0.01). Any improvement in CCS class was registered in 79 (80.6%) CTO-patients, while a significantly lower percentage (65 patients, 66.3%) of the non-CTO patients reported benefits in CCS class (p = 0.03). In conclusions, patients suffering from refractory angina with non-revascularized CTO lesions have a better response to CSR implantation than patients without CTOs. CSR implantation should be considered a valid complementary therapy to CTO-PCI in these patients
Chronic heart failure and skeletal muscle myopathy: the role of exercise training
No full textBackground: Patients with chronic heart failure (CHF) present significant skeletal muscle abnormalities, which are closely related to their prognosis. Exercise induces beneficial effects to skeletal muscles. Aim of this study was to evaluate the effect of two high intensity interval exercise training programs on the skeletal muscle myopathy of CHF patients and the additional effects of left ventricle assist device (LVAD) implantation on skeletal muscle myopathy of end stage heart failure patients. Materials and Methods: Eight consecutive HF patients (6 males, 45±15 years) were enrolled after LVAD implantation in the first part of the study. Patients were evaluated with cardiopulmonary exercise test (CPET) and respiratory function tests at 1, 3 and 6 months. The second part of the study consisted of 13 stable CHF patients (males, age: 51±13 yrs, BMI: 27±4 kg/m2) that participated, after stratified randomization, at a rehabilitation program of 36 sessions (3/week), on cycle ergometers. Six patients were assigned to high intensity interval training (HIIT), exercised for 4 cycles (duration: 28 min) and 7 patients were assigned to a HIIT (14 min) combined with strength training (14 min). All patients performed a cardiopulmonary exercise test before and after the completion of the program and percutaneous needle biopsies of the vastus lateralis muscle. Measurements of skeletal muscle included: fiber type distribution, cross section area (CSA) of muscle fiber, and capillary density. The mRNA expression of IGF-1Ea, IGF-1Eb, IGF-1Ec and IGF-1R was investigated by quantitative real-time PCR.Results: The inspiratory muscle strength was significantly increased throughout the evaluation period after LVAD implantation in all patients (59±19 vs 93±20, cmH2O, p<0.05). Moreover, the LVAD patients showed a significant increase in exercise capacity. Patients attended to both HIIT protocols significantly improved their exercise capacity. HIIT group increased the type II fibers’ CSA from 4646±880 to 5292±798 μm2, while combined HIIT group increased type II fibers’ CSA from 4265±1198 to 4525±1155 μm2 (p<0.05, between groups). After 3 months of exercise training, a significant 21% increase of type I fibers was observed, from 42±10 to 51±7% (p<0.001). Capillary to fiber ratio increased by 24 % (p=0.005). An increased expression of the IGF-1Ea, IGF-1Eb and IGF-1Ec transcripts was found following the exercise training compared with the pre-exercise expression levels [1.7±0.8; p=0.01, 1.5±0.8; p=0.03 και 2.0±1.3; p=0.02, fold changes, respectively]. IGF-1R expression levels showed no changes. The increase of muscle fibers’ CSA correlated with the increase of IGF-1Eα (r=0.62, p=0.02) and IGF-1Εb (r=0.65, p=0.02).Conclusions: LVAD support induces a progressive improvement of respiratory muscles indicating a possible reversal of inspiratory muscle myopathy of end stage CHF patients. Interval exercise training could possibly reverse skeletal myopathy of CHF patients. The beneficial effects of HIIT in skeletal muscle of CHF patients could be possible attributed to IGF-1 isoform-specific actions.Εισαγωγή: Οι ασθενείς με χρόνια καρδιακή ανεπάρκεια (ΧΚΑ) παρουσιάζουν διαταραχές των σκελετικών μυών, που σχετίζονται με δυσμενή πρόγνωση. Η άσκηση ασκεί ευεργετική επίδραση στους μυς. Υποθέσαμε πως η περιφερική μυοπάθεια ασθενών με ΧΚΑ θα μπορούσε να αναστραφεί με ένα πρόγραμμα διαλειμματικής άσκησης, ενώ, στην τελικού σταδίου ΧΚΑ η εμφύτευση αντλίας υποβοήθησης αριστεράς κοιλίας (ΑΥΑΚ) θα μπορούσε να έχει επιπρόσθετα οφέλη. Υλικό και Μέθοδοι: Οκτώ διαδοχικοί ασθενείς με ΧΚΑ (6 άρρενες, 45±15 ετών) συμμετείχαν στο πρώτο σκέλος της μελέτης, μετά από τοποθέτηση ΑΥΑΚ. Οι ασθενείς υπεβλήθησαν σε καρδιοαναπνευστική δοκιμασία κόπωσης (ΚΑΔΚ) και εκτίμηση των αναπνευστικών μυών στο 1ο, 3ο, και 6ο μήνα, μετά τη τοποθέτηση της ΑΥΑΚ. Το δεύτερο σκέλος της μελέτης αποτέλεσαν 13 άρρενες ασθενείς με ΧΚΑ (ηλικία: 51±13 έτη, BMI: 27±4 kg/m2), οι οποίοι συμμετείχαν, μετά από τυχαιοποίηση, σε πρόγραμμα αποκατάστασης, σε κυκλοεργόμετρο (36 συνεδρίες, 3 φορές την εβδομάδα). Έξι ασθενείς ασκήθηκαν σε 4 κύκλους υψηλής έντασης διαλειμματικής άσκησης (διάρκεια 28 λεπτά) και 7 ασθενείς σε 2 κύκλους διαλειμματικής άσκησης (διάρκεια 14 λεπτά) σε συνδυασμό με ασκήσεις μυϊκής ενδυνάμωσης (14 λεπτά). Οι ασθενείς υπεβλήθησαν σε ΚΑΔΚ και βιοψία του τετρακέφαλου μηριαίου πριν και μετά την ολοκλήρωση του προγράμματος. Αξιολογήθηκαν οι βασικές παράμετροι της εργοσπιρομετρίας. Η παθολογοανατομική ανάλυση των μυοβιοψιών περιελάμβανε: τύπο μυϊκών ινών, το εμβαδό εγκάρσιας διατομής και την τριχοειδική αγγείωση τους. Η έκφραση των ισομορφών του ινσουλινομιμητικού αυξητικού παράγοντα-1 (IGF-1), δηλ., IGF-1Ea, IGF-1Eb και IGF-1Ec, καθώς και του υποδοχέα (IGF-1R) μελετήθηκαν με ημιποσοτική-real-time-PCR.Αποτελέσματα: Η ισχύς των αναπνευστικών μυών αυξήθηκε μετά την εμφύτευση της LVAD (από 59±19 σε 93±20, cmH2O, p<0,05). Επίσης, οι ασθενείς παρουσίασαν αύξηση της αερόβιας ικανότητας. Στους ασθενείς, που συμμετείχαν σε τρίμηνο πρόγραμμα αποκατάστασης, παρατηρήθηκε σημαντική βελτίωση της αερόβιας ικανότητας. Το εμβαδό εγκάρσιας διατομής των μυϊκών ινών αυξήθηκε κατά 10% (από 4479±1020 σε 4922±1001μm2, p<0,001). Ειδικότερα από 4646±880 σε 5292±798μm2, στην ομάδα διαλειμματικής άσκησης και από 4265±1198 σε 4525±1155μm2 στην ομάδα συνδυασμένης άσκησης (εμφανίζοντας σημαντική μεταβολή μεταξύ ομάδων p<0,05). Oι ίνες τύπου Ι αυξήθηκαν από 42±10 σε 51±7% (p<0,001) και τα τριχοειδή ανά μυϊκή ίνα κατά 24% (από 1,27±0,22 σε 1,57±0,41, p=0,005). Η έκφραση των IGF-1Ea, IGF-1Eb και IGF-1Ec αυξήθηκε μετά το πρόγραμμα άσκησης (πολλαπλάσια μεταβολή σε σύγκριση με τα προασκησιακά επίπεδα: 1,7±0,8; p=0,01, 1,5±0,8; p=0,03 και 2,0±1,3; p=0,02, αντιστοίχως) χωρίς μεταβολή της έκφρασης του IGF-1R. H αύξηση της εγκάρσιας διατομής των μυϊκών ινών συσχετίστηκε με την αύξηση της έκφρασης των ισομορφών IGF-1Eα (r=0,62, p=0,02) και IGF-1Εb (r=0,65, p=0,02). Συμπεράσματα: Η ΑΥΑΚ προκαλεί προοδευτική βελτίωση της λειτουργίας των αναπνευστικών μυών, υποδηλώνοντας πιθανή αντιστροφή της μυοπάθειας των αναπνευστικών μυών των ασθενών με τελικού σταδίου ΧΚΑ. Η διαλειμματική άσκηση αναστρέφει τη περιφερική μυοπάθεια στη ΧΚΑ. Οι ευεργετικές επιδράσεις της άσκησης στο μυϊκό ιστό πιθανώς να συνδέονται με την επαγωγή της έκφρασης των ισομορφών του αυξητικού παράγοντα IGF-1 στους ασκηθέντες μυς
Impact of horizontal aorta on procedural and clinical outcomes in second-generation transcatheter aortic valve implantation
No full textAims: The aim of this study was to evaluate the impact of a horizontal aorta (HA) on device success and short-term clinical outcomes of transcatheter aortic valve implantation (TAVI). Methods and results: We retrospectively assessed 547 consecutive patients treated with transfemoral second-generation non-balloon-expandable (NBE) (n=447) and balloon-expandable (BE) (n=100) TAVI for symptomatic severe aortic stenosis. Aortic angulation (AA) was evaluated with preprocedural computed tomography. Patients were dichotomised according to a previously established AA cut-point: HA group (AA =48 degrees, n=230) and normal aorta (NA) group (AA <48 degrees, n=317). Endpoints were considered according to the Valve Academic Research Consortium-2 definitions. Fluoroscopy time (32.8 +/- 16.4 vs 30.3 +/- 13.9 minutes, p=0.060) and radiation dose (kerma area product 120.8 +/- 99.7 vs 103.7 +/- 81.1 Gycm2, p=0.033) were higher in the HA group as compared to the NA group. No difference in device success was observed between patients with and without an HA (88.3% vs 88.0%, p=0.929). No differences in device success and 30-day outcomes were observed when comparing HA and NA patients, according to BE and NBE prostheses. Conclusions: The presence of an HA has no impact on device success and short-term clinical outcomes of TAVI with either second-generation NBE or BE devices
Coronary sinus size and ischemia improvement after reducer implantation; “one size to fit them all?”
No full textAim: Coronary sinus (CS) reducer implantation is associated with symptomatic relief of patients with refractory angina. However, 15% to 30% of the patients do not respond to this treatment. Aim if this study was to evaluate the effect of CS size in the effectiveness of the device. Methods: Prior to device implantation and at 4-month resting ventricular function was assessed by stress cardiac magnetic resonance. Ischemia was assessed by the myocardial perfusion reserve index (MPRI). Results: Fifteen patients (66 ± 10 years) underwent successful CS Reducer implantation, with improvements in angina class and exercise tolerance. Patients with a smaller CS size (<5.8 mm) presented a significantly higher percentage increase in MPRI (63 ± 51 vs 9 ± 30%, P =.03) and a higher reduction in left ventricle end-diastolic volumes. Conclusions: Greater benefits, in terms of ischemia improvement, after CS Reducer implantation were seen in patients with smaller CS sizes, suggesting a potential mechanism underlying the observed rates of reducer non-responsiveness
Mining for Mutually Exclusive Items in Transaction Databases
No full textAssociation rule mining is a popular task that involves the discovery of co-occurences of items in transaction databases. Several extensions of the traditional association rule mining model have been proposed so far; however, the problem of mining for mutually exclusive items has not been directly tackled yet. Such information could be useful in various cases (e.g., when the expression of a gene excludes the expression of another), or it can be used as a serious hint in order to reveal inherent taxonomical information. In this article, we address the problem of mining pairs of items, such that the presence of one excludes the other. First, we provide a concise review of the literature, then we define this problem, we propose a probability-based evaluation metric, and finally a mining algorithm that we test on transaction data.</p
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