The role of self-trapped excitons in polaronic recombination processes in lithium niobate.

Transient absorption and photoluminescence are experimentally investigated in the polaronic reference system lithium niobate, LiNbO[Formula: see text] (LN), with the aim to refine the microscopic model of small polaron dynamics in materials with strong electron-phonon coupling. As a unique feature, our study is performed by using two different spectroscopic methods, in crystals with dopants enhancing photorefraction or damage resistance, and over a broad temperature range from 15-400 K. Although being self-consistent for particular experimental conditions, the hitherto used microscopic polaronic models reveal inconsistencies when applied to this larger data set. We show that comprehensive modeling is unlocked by the inclusion of an additional type of polaronic state with the following characteristics: (i) strongly temperature- and dopant-dependent relaxation times, (ii) an absorption feature in the blue-green spectral range, and (iii) a Kohlrausch-Williams-Watts decay shape with a temperature-dependent stretching factor [Formula: see text] showing a behavior contrary to that of small, strong-coupling polarons. The hypothesis of self-trapped excitons (STEs, i.e. bound electron-hole pairs strongly coupled to Nb[Formula: see text] and O[Formula: see text] within a niobium-oxygen octahedron) and their pinning on defects as the microscopic origin of these characteristics is supported by a spectroscopic linkage of photoluminescence at low (15 K) and elevated (300 K) temperatures and explains the long-lifetime components in transient absorption as due to pinned STEs.

Comparison of 26-week efficacy and tolerability of telmisartan and atenolol, in combination with hydrochlorothiazide as required, in the treatment of mild to moderate hypertension: a randomized, multicenter study.

OBJECTIVE: This study was undertaken to compare the efficacy and tolerability of telmisartan, a novel antihypertensive agent, and atenolol, a well-established beta-blocker, in the treatment of mild to moderate hypertension. METHODS: This 26-week, multicenter, randomized, double-blind, double-dummy, parallel-group, titration-to-response study compared doses of telmisartan (40 mg titrated to 80 mg titrated to 120 mg) with atenolol (50 mg titrated to 100 mg) required to achieve diastolic blood pressure (DBP) control (< or = 90 mm Hg or a decrease from baseline of > or = 10 mm Hg). Open-label hydrochlorothiazide (HCTZ) 12.5 or 25 mg was added if needed according to a prespecified titration rule. Men and women aged > 18 years with mild to moderate hypertension (morning mean supine DBP [SDBP] > or = 95 mm Hg and < or = 114 mm Hg) were eligible to participate. Patients with significant cardiovascular, metabolic, hepatic, or renal dysfunction or chronic obstructive pulmonary disease were excluded. The primary efficacy end point was trough SDBP response at 26 weeks; secondary efficacy end points included changes from baseline at trough in both standing and supine DBP and systolic blood pressure (SBP), and heart rate after 4, 8, 16, and 26 weeks; SBP control (reduction from baseline of > or = 10 mm Hg); normalization of supine SDBP to < or = 90 mm Hg; and the need for add-on HCTZ. Changes in quality of life were also examined. Adverse events were obtained from spontaneous reporting and recorded. Serious adverse events were reported to the sponsor according to predefined timelines. RESULTS: A total of 533 patients from 49 centers participated. Patients' mean age was 57.9 years (range, 22-79 years); 55.9% (298/533) of the population was male and 98.1% (523/533) was white. Of the 533 patients randomly assigned to treatment and included in the safety analysis, 520 (97.6%) were included in the efficacy analysis; 346 received telmisartan and 174 received atenolol. A total of 489 patients (91.7%) completed the study (325 [93.9%], telmisartan; 164 [94.2%], atenolol). Full SDBP response (trough SDBP < or = 90 mm Hg and/or a reduction from baseline of > or = 10 mm Hg) was observed in 84% and 78% of telmisartan- and atenolol-treated patients, respectively; this difference was not statistically significant. Final SBP/DBP reductions of 20.9/14.4 mm Hg were observed for the telmisartan regimen versus 16.7/13.3 mm Hg for the atenolol regimen; only the difference in SBP was significant (P = 0.005). Reduction from baseline in SBP of > or = 10 mm Hg was achieved by 80% of telmisartan-treated and 68% of atenolol-treated patients (P = 0.003). Adverse events were reported by 52.7% of patients given telmisartan and 61.2% of patients given atenolol; this difference was not statistically significant. Most events were mild or moderate. Although fatigue and male impotence were more common in atenolol-treated patients (3.4% and 4.0%, respectively), the incidence of these adverse events was too low to differentiate statistically. CONCLUSIONS: Telmisartan appears to be at least as effective as atenolol in the treatment of mild to moderate hypertension and may be better tolerated.

Valsartan, a new angiotensin II antagonist for the treatment of essential hypertension: efficacy and safety compared to hydrochlorothiazide.

OBJECTIVE: To compare the antihypertensive efficacy of a new angiotensin II antagonist, valsartan, with a reference therapy, hydrochlorothiazide (HCTZ). METHODS: In this double-blind study, 167 adult out-patients with mild-to-moderate essential hypertension were randomly allocated in equal number to receive valsartan 80 mg or HCTZ 25 mg for 12 weeks. In patients whose blood pressure (BP) remained uncontrolled after 8 weeks of monotherapy, atenolol 50 mg was added to the initial treatment. Patients were assessed at 4, 8 and 12 weeks. The primary efficacy variable was change from baseline in mean sitting diastolic BP (SDBP) at 8 weeks. Secondary variables included change in sitting systolic BP (SSBP) and responder rates (percentage of patients with SDBP < 90 mmHg or drop > or = 10 mmHg compared to baseline) at 8 weeks. RESULTS: Valsartan and HCTZ were both effective at lowering diastolic and systolic blood pressure at all time points. Similar falls were seen in both groups with no significant differences between treatments. For the primary variable (decrease in SDBP) there was no significant difference between treatments. For SSBP there was also no significant difference observed. Responder rates at 8 weeks were 74% for valsartan and 62% for HCTZ (P = 0.10). Both treatments were well tolerated, both as monotherapy, and when combined with atenolol 50 mg per day. CONCLUSION: The data show valsartan 80 mg to be as effective as HCTZ in the treatment of mild-to-moderate hypertension. The results also show valsartan to be well tolerated when taken alone or in combination with atenolol.