Low temperature thermoluminescence of β-Ga2O3 scintillator

Low temperature thermoluminescence of β-Ga2O3, β-Ga2O3:Al and β-Ga2O3:Ce has been investigated. Glow curves have been analyzed quantitatively using a rate equations model in order to determine the traps parameters, such as activation energies, capture cross-sections and probabilities of recombination and retrapping

Blood flow velocity in the middle cerebral artery during transnasal endoscopic skull base surgery performed in controlled hypotension

Background and purpose To assess blood flow velocity in the middle cerebral artery (MCA) during transnasal endoscopic procedures performed with decreased hemodynamic parameters. Materials and methods In 40 patients who underwent endoscopic skull base surgery in controlled hypotension (studied group) and in 13 patients operated without reduction of hemodynamic parameters (control group), blood flow velocity in MCA was assessed with transcranial color Doppler sonography. Results Blood flow velocity in MCA remained within the range of age-specific reference values in all patients before operation. It decreased significantly in both groups after induction of anesthesia and then dropped even further in studied group of patients when hemodynamic parameters were reduced; the systolic velocity fell below the normal reference values in 25% of patients, the mean velocity in 50% and the diastolic velocity in 57% of patients. The diastolic velocity was much more heavily influenced by diminished hemodynamic parameters than systolic velocity in the studied group as opposed to the control group where reduction of blood flow velocity pertained equally systolic and diastolic velocity. Conclusion During transnasal endoscopic procedures performed in moderate hypotension, in addition to significant drop of blood flow velocity to values well below the normal reference range, a divergent reduction of systolic and diastolic velocity was detected. Since divergent systolic and diastolic velocity may indicate an early phase of cerebral autoregulation compromise, and the decrease of mean blood flow velocity in MCA corresponds with a decrease of cerebral blood flow, further investigations in this field seem warranted

MEDtube Science

ABSTRACT Kidney transplantation from a living donor is a method of choice in the treatment of end-stage renal disease. The programme of care for a living kidney donor should cover the assessment of health status and quality of life and an analysis of the data collected on the basis of the same criteria. The conclusions drawn should be used in the assessment of the risk associated with the kidney harvesting procedure, assessment of the health status of the living donor and an improvement of the results of kidney transplantation from a living donor

A new method of detecting sleep apnea and hypopnea episodes in airflow signal recordings

Wstęp: W klinikach pneumonologicznych stosuje się komercyjne programy komputerowe dookreślania stopnia nasilenia bezdechu sennego. Poważnym problemem w tych programachjest niewystarczająca czułość zastosowanych algorytmów.Cel pracy: Ocena czułości i swoistości nowo opracowanej metody wykrywania epizodówbezdechu sennego oraz spłycenia oddechu.Materiał i metody: Dokonano szczegółowej analizy 10 badań polisomnograficznych. Zbadanoczułość i swoistość opracowanej metody oraz porównano ją z wynikami analiz uzyskanychz komercyjnych programów komputerowych.Wyniki: Opracowana metoda osiąga czułość powyżej 80% (przy zachowaniu wysokiej swoistości),czułość porównywanego programu komercyjnego uzyskuje poziom 60% poprawnychrozpoznań.Wnioski: Wyniki badań potwierdzają wysoką czułość i swoistość opracowanej metodyoraz wskazują na konieczność poprawy algorytmów w obecnie stosowanych programachkomercyjnych do badań polisomnograficznych.Background: In sleep clinics commercial computer programs are used to determine theseverity of sleep apnea. A major problem is the insufficient se nsitivity of the algorithmsused in these programs.Objectives: Evaluation of the effectiveness of a new method for detecting sleep apnea andhypopnea episodes.Material and methods: A detailed ana lysis of 10 polys omnographic records was carriedout. The sensitivity and specificity of the proposed method was examined and comparedwith the analysis carried out by commercial computer programs.Results: The proposed method has an average sensitivity of over 80% (while maintaininghigh specificity), where the sensitivity of the computer progra m was recorded at 60% ofcorrect detections.Conclusions: The results confirm the high sensitivity and specificity of the new method andindicate the need to improve the algorithms in commercial computer programs which arecurrently used in sleep clinics to analyze polysomnographic records

Tailoring the Scintillation Properties of β-Ga2O3 by Doping with Ce and Codoping with Si

Measurements of pulse height spectra and scintillation time profiles performed on Czochralski-grown β-Ga2O3, β-Ga2O3:Ce, and β-Ga2O3:Ce,Si crystals are reported. The highest value of scintillation yield, 7040 ph/MeV, was achieved for pure β-Ga2O3 at a low free electron concentration, nevertheless Ce-doped crystals could also approach high values thereof. Si-codoping, however, decreases the scintillation yield. The presence of Ce, and the more of Ce and Si, in β-Ga2O3 significantly increases the contribution of the fastest components in scintillation time profiles, which makes β-Ga2O3 a very fast scintillator under γ-excitation

Recent Progress in the Development of β-Ga2O3 Scintillator Crystals Grown by the Czochralski Method

A high-quality bulk single crystal of β-Ga2O3 has been grown by the Czochralski method and its basic scintillation characteristics (light yield, energy resolution, proportionality, and scintillation decay times) have been investigated. All the samples cut from the crystal show promising scintillation yields between 8400 and 8920 ph/MeV, which is a noticeable step forward compared to previous studies. The remaining parameters, i.e. the energy resolution slightly above 10% (at 662 keV) and the scintillation mean decay time just under 1 μs, are at the same level as we have formerly recognized for β-Ga2O3. The proportionality of yield seems not to deviate from standards determined by other commercial scintillators

Recent progress in the development of β-Ga2O3 scintillator crystals grown by the Czochralski method

A high-quality bulk single crystal of β-Ga2O3 has been grown by the Czochralski method and its basic scintillation characteristics (light yield, energy resolution, proportionality, and scintillation decay times) have been investigated. All the samples cut from the crystal show promising scintillation yields between 8400 and 8920 ph/MeV, which is a noticeable step forward compared to previous studies. The remaining parameters, i.e. the energy resolution slightly above 10% (at 662 keV) and the scintillation mean decay time just under 1 μs, are at the same level as we have formerly recognized for β-Ga2O3. The proportionality of yield seems not to deviate from standards determined by other commercial scintillators

Charge traps in Ce-doped CaF2 and BaF2

Thermoluminescence of CaF2:Ce, BaF2, and BaF2:Ce irradiated at room temperature is reported. X-ray induced emission spectra of the samples show that both excitonic (due to e- + VK recombination) and Ce3+ d-f luminescence may contribute to thermoluminescence signal. The simple Randall-Wilkins model is used to deconvolute glow curves into seven to eight first-order peaks. Parameters of all traps are calculated and correlations between peaks in the curves of the examined materials are discussed

Analysis of the work states of a pulse current electric arc furnace

This article presents the results of the analysis of a six-electrode pulse current electric arc furnace (EAF). The characteristics of a power supply system for an EAF are presented for symmetrical states and the most probable asymmetrical states