Recording and erasure of photorefractive holograms in undoped BTO crystal at moderate to high intensities of 639.7 nm laser under action of 532 nm laser pre-illumination.

We investigate recording and erasure of photorefractive holographic gratings in an undoped Bi12TiO20 crystal in a moderate to high intensity regime of the recording beams at 639.7 nm without and with the action of laser pre-illumination at 532 nm. The detected hologram without pre-illumination indicates the participation of two photorefractive electronic gratings in its recording process, and the diffracted signal by itself exhibits a fivefold enhancement when the total intensity increases from 38.4 to 214.5 mW/cm2. The dependence of the measured total diffraction efficiency on intensity was investigated and showed linear behavior. At least three gratings are present in the regime of pre-illumination and participate in the writing and erasure of holographic mechanisms. Two of them are electronic, and one is hole-based, with a phase difference of Δϕ between them. The theoretical approach used to analyze the total diffraction efficiency based upon the photorefractivity standard model, and considering the presence of the three gratings, showed good agreement with the holographic erasure experimental data and permitted us to compute Δϕ, which exhibited strong and unusual dependence on the total intensity.

134Cs activity standardization by 4πß(LS)-γ(NaI-Tl) anticoincidence counting and submission to international reference system.

From a commercial supplier a solution containing 134Cs has been standardized at National Laboratory for Ionizing Radiation Metrology (LNMRI) for the first time using three Liquid scintillation based measurement. These measurement methods are 4πß-γ live-timed anticoincidence counting, 4πß-γ coincidence counting and 3H-standard efficiency tracing with the CNET methods. The results obtained by anticoincidence counting was adopted as reference value and its combined uncertainty was 0.38%. The agreement of this reference value with coincidence counting and CNET methods were 0.39% and 0.34% respectively and were in consistency with each uncertainty method. The weighted mean results coincidence counting and CNET methods are also in close agreement 0.03% with anticoincidence counting method and meets the requirement of primary and national standard. This standardization was made in order to reduce the uncertainty in 134Cs measurement in Brazil and also following a request made by Bureau International des Poids and Mesures for new submission to International Reference System. The LNMRI last submission was made in 1987. Therefore from a 134Cs master solution a NIST ampoules was prepared and LNMRI/IRD submitted it to the International Reference System, Bureau International of Poids and Measures (SIR/BIPM). In this paper will be analyzed the LNMRI measurement and performance each measurement methods and also take into account the reference value of KCDB, we determined also the 134Cs gamma emission probabilities of main energy.

Application of the sum-peak method to activity standardizations of 152Eu sources in LNMRI (BR).

The sum-peak method, an absolute measurement technique that uses coincidence counting and γ-ray spectrometry, was applied to activity standardization of 152Eu sources. The decay branch used was that of 152Sm, as it is almost entirely electron capture and exhibits X-rays with a high probability of coincidence with the 121.8keVgamma rays, as evidenced by the matrix technique used for complex decay schemes, a method for deriving counting rate equations describing coincidence summing of gamma and X-rays. The result was compared with the calibration performed by ionization chamber traceable to BIPM. The results presented uncertainty values of 0.50% (k = 1).

Absolute standardization of the impurity (121)Te associated to the production of the radiopharmaceutical (123)I.

(123)I is widely used for radiodiagnostic procedures. It is produced by reaction of (124)Xe (p,2n) (123)Cs →(123)Xe →(123)I in cyclotrons. (121)Te and (125)I appear in a photon energy spectrum as impurities. An activity of (121)Te was calibrated absolutely by sum-peak method and its photon emitting probability was estimated, whose results were consistent with published results.

Determination of impurities in (124)I samples by high resolution gamma spectrometry.

(124)I is a radionuclide used in the diagnosis of tumors. The National Health Agency requires identification and activity measurement of impurities. Using gamma spectrometry with an efficiency calibrated high-purity germanium detector, impurities (125)I and (126)I in an (1)(24)I production sample were identified. Activity ratios of (125)I and (126)I to (124)I were approximately 0.5% and 98%, respectively.

Root damage associated with intermaxillary screws: a systematic review.

This systematic review examined the literature for evidence of dental root damage after contact with intermaxillary screws (IMS). Electronic databases, including the Cochrane Library, Ovid, Scirus, Scopus and Virtual Health Library, were used to search for original articles from 1980 to January 2011. Prospective and retrospective studies that assessed the association of root damage and contact with IMS were selected. Two authors independently reviewed and extracted the data from the included studies. A methodological quality scoring process was used to classify whether the articles presented low, moderate or high evidence. The search retrieved 795 citations. Nine studies fulfilled the initial selection criteria. Of these studies, 3 were excluded. Two studies did not note any iatrogenic injuries of the dental roots; the other study was a case report. Of the 6 included articles, 2 were ranked as having low and four as having moderate evidence. The moderate evidence found suggested that the roots did not exhibit clinical changes after coming into contact with the IMS, but this situation depends on the root damage level. To obtain reliable scientific evidence, studies with an adequate sample size and diagnostic methods are required to confirm the effects of IMS on the dental root.

A critical view on antimalarial endoperoxide QSAR studies.

Malaria is one of the most dangerous diseases in developing countries. The chemotherapy of malaria has been based on drugs developed more than half a century ago. These drugs are continuously losing their efficacy, mainly due to multi-drug resistance developed by the malaria-causing parasite. In the last three decades, artemisinin and artemisinin-like compounds have proven to be efficient alternatives to the chemotherapeutic control of malaria. These facts have led to an increasing interest in the development of Quantitative Structure Activity Relantioship (QSAR) models for these compounds. This work presents a critical view on some QSAR models, and shows that, due to lack of a rigorous selection of the descriptors entering the models, most of them are unable to accurately indicate the molecular cause of biological activity. Some reasons for the weakness of the published models are discussed.

Color tunability with temperature and pump intensity in Yb3+/Tm3+ codoped aluminosilicate glass under anti-Stokes excitation.

Pump and thermally induced color tunabilities were demonstrated in Yb(3+)/Tm(3+) codoped low silica calcium aluminosilicate (LSCAS) glass under anti-Stokes excitation at 1.064 microm. The effects of pump intensity and sample's temperature on the upconversion emissions and mainly on the color tunabilities (from 800 to 480 nm) were investigated. The results revealed a 20- and a threefold reductions at 800/480 nm ratio as, respectively, the pump intensity and sample's temperature were increased from 27 to 700 kW/cm(2) and from 296 to 577 K. These behaviors with pump intensity and temperature (a strong increase of the 480 nm emission in comparison with the 800 nm one) were attributed to the several efficient processes occurring in the LSCAS system (Yb(3+)-->Tm(3+) energy-transfer processes, easy saturations of the Yb(3+) and Tm(3+) excited states, and radiative emissions). Besides these assigns, the temperature dependence is mainly assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. Theoretical analyses and fits of the experimental data provided quantitative information.

Influence of renal denervation on blood pressure, sodium and water excretion in acute total obstructive apnea in rats.

Obstructive apnea (OA) can exert significant effects on renal sympathetic nerve activity (RSNA) and hemodynamic parameters. The present study focuses on the modulatory actions of RSNA on OA-induced sodium and water retention. The experiments were performed in renal-denervated rats (D; N = 9), which were compared to sham (S; N = 9) rats. Mean arterial pressure (MAP) and heart rate (HR) were assessed via an intrafemoral catheter. A catheter was inserted into the bladder for urinary measurements. OA episodes were induced via occlusion of the catheter inserted into the trachea. After an equilibration period, OA was induced for 20 s every 2 min and the changes in urine, MAP, HR and RSNA were recorded. Renal denervation did not alter resting MAP (S: 113 +/- 4 vs D: 115 +/- 4 mmHg) or HR (S: 340 +/- 12 vs D: 368 +/- 11 bpm). An OA episode resulted in decreased HR and MAP in both groups, but D rats showed exacerbated hypotension and attenuated bradycardia (S: -12 +/- 1 mmHg and -16 +/- 2 bpm vs D: -16 +/- 1 mmHg and 9 +/- 2 bpm; P < 0.01). The basal urinary parameters did not change during or after OA in S rats. However, D rats showed significant increases both during and after OA. Renal sympathetic nerve activity in S rats increased (34 +/- 9%) during apnea episodes. These results indicate that renal denervation induces elevations of sodium content and urine volume and alters bradycardia and hypotension patterns during total OA in unconscious rats.

Influence of renal denervation on blood pressure, sodium and water excretion in acute total obstructive apnea in rats

Obstructive apnea (OA) can exert significant effects on renal sympathetic nerve activity (RSNA) and hemodynamic parameters. The present study focuses on the modulatory actions of RSNA on OA-induced sodium and water retention. The experiments were performed in renal-denervated rats (D; N = 9), which were compared to sham (S; N = 9) rats. Mean arterial pressure (MAP) and heart rate (HR) were assessed via an intrafemoral catheter. A catheter was inserted into the bladder for urinary measurements. OA episodes were induced via occlusion of the catheter inserted into the trachea. After an equilibration period, OA was induced for 20 s every 2 min and the changes in urine, MAP, HR and RSNA were recorded. Renal denervation did not alter resting MAP (S: 113 ± 4 vs D: 115 ± 4 mmHg) or HR (S: 340 ± 12 vs D: 368 ± 11 bpm). An OA episode resulted in decreased HR and MAP in both groups, but D rats showed exacerbated hypotension and attenuated bradycardia (S: -12 ± 1 mmHg and -16 ± 2 bpm vs D: -16 ± 1 mmHg and 9 ± 2 bpm; P < 0.01). The basal urinary parameters did not change during or after OA in S rats. However, D rats showed significant increases both during and after OA. Renal sympathetic nerve activity in S rats increased (34 ± 9 percent) during apnea episodes. These results indicate that renal denervation induces elevations of sodium content and urine volume and alters bradycardia and hypotension patterns during total OA in unconscious rats.

Deep and shallow trap contributions to the ionic current in the thermal-electric field poling in soda-lime glasses.

In this paper, we investigate the contribution of deep and shallow trapped ions on the second-order nonlinearity during typical poling procedures in soda-lime glass. The zero-electric field potential barriers of each contribution were estimated. The shallow traps, measured through the electrical ionic current, was determined as ~0.34 eV; while deep trap activation energy, measured by means of the thermal/electric field activated luminescence, was estimated ~3.8 eV. The traps show different dependence on its thermal energy onset for different applied electric field. The ionic current is linearly dependent on the electric field. The luminescence has a minimum electric field ~3.6 kV/cm and thermal energy ~31 meV (~87 degrees C) to occur. The average ionic jump lengths for both processes are also estimated, and the deep trap length is about ten times shorter than the shallow trap one. Samples poled at the border of the luminescence onset parameters revealed that the higher its contributions the more stable the induced second order nonlinearity.

Thermal lens study of energy transfer in Yb(3+)/Tm(3+)-co-doped glasses.

Energy transfer (ET) and heat generation processes in Yb(3+)/Tm(3+)-co-doped low-silica calcium-aluminosilicate glasses were investigated using thermal lens and photoluminescence measurements. Stepwise ET processes from Yb(3+) to Tm(3+), with excitation at 0.976 mum, produced efficient emission in the mid-infrared range at around 1.8 mum, with high fluorescence quantum efficiency (~0.50) and relatively low thermal loading (

Transitory increased blood pressure after upper airway surgery for snoring and sleep apnea correlates with the apnea-hypopnea respiratory disturbance index.

A transitory increase in blood pressure (BP) is observed following upper airway surgery for obstructive sleep apnea syndrome but the mechanisms implicated are not yet well understood. The objective of the present study was to evaluate changes in BP and heart rate (HR) and putative factors after uvulopalatopharyngoplasty and septoplasty in normotensive snorers. Patients (N = 10) were instrumented for 24-h ambulatory BP monitoring, nocturnal respiratory monitoring and urinary catecholamine level evaluation one day before surgery and on the day of surgery. The influence of postsurgery pain was prevented by analgesic therapy as confirmed using a visual analog scale of pain. Compared with preoperative values, there was a significant (P < 0.05) increase in nighttime but not daytime systolic BP (119 5 vs 107 3 mmHg), diastolic BP (72 4 vs 67 2 mmHg), HR (67 4 vs 57 2 bpm), respiratory disturbance index (RDI) characterized by apnea-hypopnea (30 10 vs 13 4 events/h of sleep) and norepinephrine levels (22.0 4.7 vs 11.0 1.3 g l-1 12 h-1) after surgery. A positive correlation was found between individual variations of BP and individual variations of RDI (r = 0.81, P < 0.01) but not between BP or RDI and catecholamines. The visual analog scale of pain showed similar stress levels on the day before and after surgery (6.0 0.8 vs 5.0 0.9 cm, respectively). These data strongly suggest that the cardiovascular changes observed in patients who underwent uvulopalatopharyngoplasty and septoplasty were due to the increased postoperative RDI.

Transitory increased blood pressure after upper airway surgery for snoring and sleep apnea correlates with the apnea-hypopnea respiratory disturbance index

A transitory increase in blood pressure (BP) is observed following upper airway surgery for obstructive sleep apnea syndrome but the mechanisms implicated are not yet well understood. The objective of the present study was to evaluate changes in BP and heart rate (HR) and putative factors after uvulopalatopharyngoplasty and septoplasty in normotensive snorers. Patients (N = 10) were instrumented for 24-h ambulatory BP monitoring, nocturnal respiratory monitoring and urinary catecholamine level evaluation one day before surgery and on the day of surgery. The influence of postsurgery pain was prevented by analgesic therapy as confirmed using a visual analog scale of pain. Compared with preoperative values, there was a significant (P < 0.05) increase in nighttime but not daytime systolic BP (119 ± 5 vs 107 ± 3 mmHg), diastolic BP (72 ± 4 vs 67 ± 2 mmHg), HR (67 ± 4 vs 57 ± 2 bpm), respiratory disturbance index (RDI) characterized by apnea-hypopnea (30 ± 10 vs 13 ± 4 events/h of sleep) and norepinephrine levels (22.0 ± 4.7 vs 11.0 ± 1.3 æg l-1 12 h-1) after surgery. A positive correlation was found between individual variations of BP and individual variations of RDI (r = 0.81, P < 0.01) but not between BP or RDI and catecholamines. The visual analog scale of pain showed similar stress levels on the day before and after surgery (6.0 ± 0.8 vs 5.0 ± 0.9 cm, respectively). These data strongly suggest that the cardiovascular changes observed in patients who underwent uvulopalatopharyngoplasty and septoplasty were due to the increased postoperative RDI.

Neurological teleconsultation for general practitioners.

A neurology teleconsulting network was implemented between a university hospital in Lisbon and five nearby health centres. PCs equipped for videoconferencing were installed, connected by ISDN lines at 128 kbit/s. Fifty-three general practitioners (GPs) were surveyed. The survey showed that the GPs had difficulties in using computers, but they had definite intentions to use teleconsultation for neurology cases and 83% of the respondents stated that they would probably use the technique. During the study, 90 neurology teleconsultations took place over 55 weeks. The average consultation rate was 1.6 teleconsultations per week (SD 1.3, range 0-6). The conferences lasted 10-45 min. Longer teleconsultations were mainly due to technical difficulties in using computers on the part of users with a low level of computer literacy. The patients were 42 males and 46 females, with a mean age of 38 years (SD 20, range 1-84); two patients were discussed twice. The benefits consisted mainly of advice on patient medication, diagnosis and the prevention of unnecessary specialist consultations or laboratory examinations. Doctor-doctor teleconsultation allows the rapid resolution of queries which otherwise cause stress to patients and increase the cost and complexity of care.

Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy.

STUDY OBJECTIVES: The objectives of this study were (1) to evaluate the way in which nasal continuous positive airway pressure (CPAP) therapy influences the relative humidity (rH) of inspired air; and (2) to assess the impact on rH of the addition of an integrated heated humidifier or a full face mask to the CPAP circuitry. DESIGN: The studies were performed in 25 patients with obstructive sleep apnea syndrome receiving long-term nasal CPAP therapy and complaining of nasal discomfort. During CPAP administration, temperature and rH were measured in the mask either during a night's sleep for 8 patients or during a daytime study in which the effects of mouth leaks were simulated in 17 patients fitted with either a nasal mask (with or without humidification) or a face mask alone. SETTING: University hospital sleep disorders center. MEASUREMENTS AND RESULTS: Compared with the values obtained with CPAP alone, integrated heated humidification significantly increased rH during the sleep recording, both when the mouth was closed (60 +/- 14% to 81 +/- 14%, p < 0.01) and during mouth leaks (43 +/- 12% to 64 +/- 8%, p < 0.01). During the daytime study, a significant decrease in rH was observed with CPAP alone. Compared with the values measured during spontaneous breathing without CPAP (80 +/- 2%), the mean rH was 63 +/- 9% (p < 0.01) with the mouth closed and 39 +/- 9% (p < 0. 01) with the mouth open. The addition of heated humidification to CPAP prevented rH changes when the mouth was closed (82 +/- 12%), but did not fully prevent the rH decrease during simulation of mouth leaks (63 +/- 9%) compared with the control period (80 +/- 2%, p < 0. 01). Finally, attachment of a face mask to the CPAP circuitry prevented rH changes both with the mouth closed (82 +/- 9%) and with the mouth open (84 +/- 8%). CONCLUSIONS: These data indicate that inhaled air dryness during CPAP therapy can be significantly attenuated by heated humidification, even during mouth leaks, and can be totally prevented by using a face mask.