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Two-photon excitation with femtosecond laser pulses in the spectral range 240–250 nm was used to prepare vapor phase H2O and D2O in the C 1B1 and D 1A1 states. Both states are predissociated via the B 1A1 state, forming excited OH/OD(A 2Σ+) as well as ground state OH/OD(X 2Π). We used ultrashort infrared probe pulses (1.65–2.42 μm) to control the ratio between these excited and ground state fragments originating from the dissociation process. Time resolved detection of the OH/OD(A 2Σ+)→OH/OD(X 2Π) fluorescence allows us to monitor the dynamics of the predissociation. For the heterogeneous predissociation out of the C 1B1 state life times of (0.5±0.1) ps and (1.2±0.1) ps were found for H2O and D2O, respectively. The purely homogeneous character of the predissociation out of the D 1A1 state was monitored. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The frequency and temperature dependence of the longitudinal proton relaxation time T1 has been studied in liquid crystal droplets embedded in a solid polymer matrix in the nematic and isotropic phase over a broad Larmor frequency range (500 Hz≤νL≤84 MHz) employing the fast-field-cycling technique. The comparison of the droplet data, bulk 5CB data, and the pure polymer data show that T1 is dominated by the cross relaxation at the liquid crystal–polymer interface in the entire frequency range. In the low frequency range (νL≤1 MHz), an additional relaxation process determines T1 in both phases, namely reorientations mediated by translational replacements in the nematic phase and the exchange relaxation in the isotropic phase. The analysis of the cross relaxation rate k reveals that the simplified model of Vilfan is only applicable in the nematic phase and leads to an anchoring time τAS of the molecules at the surface which is ≊1.3×10-4 s. This model, however, cannot be applied in the isotropic phase, but must be extended by the spin diffusion time τP, which in this case determines the cross relaxation rate. The anchoring time τAS, which in the isotropic phase corresponds to the correlation time of the additional process, is much shorter than in the nematic phase, namely τAS≊10-6 s. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Introduction: Cardiovascular diseases are the main cause of death in Chile. Among them, High Blood Pressure or Hypertension or Arterial Hypertension affects about 1/3 of the country, but only 45.9% of the population under treatment reaches normal levels of blood pressure. Objective: determinate the adherence to treatment in a group of hypertensive patients from the Health Center of Yungay's Communitarian Hospital, by using Morisky-Green Test, and analyze the factors that could be related to the level of adherence. Materials and methods: descriptive, observational and prospective study, perfomed by an interview of hypertensive patients from the Health Center of Yungay's Communitarian Hospital between August and September 2012, using Morisky-Green Test and adding other questions related to gender, age, school level, support network and number of medications. Besides, blood pressure was taken to all patients. Results: 74 patients were included. 74% were women. The age average was 65.3 years. Only 45.9% had adherence to treatment and 47.9% had blood pressure under control. Within the studied factors, 51% of patients had primary educational level incomplete and the average of antihypertensive medications was 1.75. Conclusions and Discussion: The lack of adherence to treatment is directly related to a bad blood pressure control. An increment in investigation and education of the monitoring of hypertensive patients, should be one of the main goals of the cardiovascular programs. [ABSTRACT FROM AUTHOR]

Mastocytosis comprises a heterogeneous group of hematological disorders which are morphologically defined by proliferation and accumulation of tissue mast cells in one or more organs. Clinical manifestations of mastocytosis range from disseminated maculopapular skin lesions (= urticaria pigmentosa [UP]) that may spontaneously regress to highly aggressive neoplasms like mast cell leukemia or mast cell sarcoma. Recently, it could be shown that systemic mastocytosis (SM) is a clonal disorder often exhibiting mutations of c-kit, a protooncogene encoding the tyrosine kinase receptor for stem cell factor (SCF). Mutations of c-kit are considered to play a key role in the pathogenesis of mastocytosis. Therefore, we investigated the unique case of a 36 year-old male patient with indolent systemic mastocytosis (ISM) evolving from UP (cutaneous mastocytosis) by means of histology, immunophenotyping and molecular biology. At the time of initial diagnosis the bone marrow showed only a mild diffuse increase in mast cells but compact infiltrates were missing. The serum tryptase levels were normal. Five years later, however, the bone marrow histology displayed patchy compact mast cell infiltrates, which now allowed to establish the diagnosis of an ISM. The serum tryptase levels at this time were markedly elevated. At both time points, mast cells were analyzed by immunohistochemistry using anti-tryptase antibody AA1, by flow cytometry using antibodies against CD2 and CD25, and nested polymerase chain reaction (PCR) on laser-microdissected, single pooled mast cells. Immunohistochemistry revealed strong tryptase-positivity of mast cells in both cutaneous and bone marrow infiltrates. Flow cytometry yielded an aberrant expression of CD2 and CD25 on bone marrow mast cells. However, repeated thorough PCR analysis failed to unveil c-kit mutation in atypical mast cells of skin and bone marrow samples of both dates. These findings clearly show that ISM can evolve from UP. Moreover, our... [ABSTRACT FROM AUTHOR]

We developed a high-power oscillator-regenerative amplifier femtosecond laser system. Based on chromium-doped forsterite. The system is operating near 1.25 µm at a 5-10kHz repetition rate. Chirped-pulse amplification produced 0.86 W (0.75 W) of average power, or 465 mW (400 mW) after compression at 5 kHz (10 kHz). Nearly bandwidth-limited pulses of duration 135 fs (shortest) and 150 fs (typical) are available with an energy of 93 µJ and 40 µJ at 5 and 10 kHz, respectively. [ABSTRACT FROM AUTHOR]

Reports the very rare case of a primary malignant mixed Mullerian tumors (MMMT) arising in the rectosigmoid. Information on the case of a 79-year-old female patient presented with rectal bleeding and a history of weight loss diagnosed with polypoid ulcerating tumor of the rectosigmoid colon diffusely infiltrating the mesocolon; Histogenesis of MMMT.

This paper reports on studies of the longitudinal proton spin relaxation dispersion T1Z(ω) of a nematic main chain liquid crystal polymer (Mn=30 000) over a very broad Larmor frequency range (1 kHz≤ω/2π≤120 MHz). Analysis of the experiments is achieved in terms of a density operator treatment employing the Redfield approximation. The results show that collective motions contribute to the proton spin relaxation process in the kilohertz regime, as found for low molar mass liquid crystals, whereas the conventional megahertz range is dominated by reorientation of individual molecules. The intramolecular motions consist of trans–gauche isomerization and phenyl ring flips. These motions are the fastest in the hierarchy of time with correlation times of 10-10 s in the nematic melt of the polymer at T≊460 K. The intermolecular (whole molecule) motions are interpreted as rotational diffusion in an orienting potential. They exhibit a T1Z(ω)∼ω0.65 dispersion in the megahertz range and have correlation times ranging from 10-9 to 10-7 s at this temperature. The slowest motions affecting longitudinal spin relaxation can be assigned to nematic order director fluctuations characterized by a broad distribution of thermally activated modes. Analysis of the dispersion profiles in the kilohertz regime provides the viscoelastic parameters of the main chain liquid crystal polymer. At T=460 K, an average elastic constant of K=8×10-11 N and an effective viscosity of η=1×103 Pa s have been determined. Using the experimentally accessible value for the short wavelength cutoff of the elastic modes, one obtains the mean-square amplitude of the director fluctuations <θ02>==0.02, corresponding to a director order parameter of SOF=0.98. Thus, the contributions of the collective chain motions to the measured order parameters are negligible. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about colitis cystica profunda and inflammatory pseudopolyp in Crohn's disease.

A letter to the editor is presented in response to an article about angiosarcoma, a very rare vascular neoplasm.

Values for the nonlinear refractive index (n[sub 2] ≈ 5.4 × 10[sup -5] cm[sup 2]/GW) are reported as well as the two-photon absorption coefficient (β ≈ 0.25 cm/GW) in ZnGeP[sub 02] at wavelengths near half the band edge of this semiconductor nonlinear optical crystal. The Z-scan measurements were performed with a mode-locked femtosecond Cr:forsterite laser at 1.26 μm and 83 MHz, and the nonlinear transmission measurements were accomplished by a near infrared traveling wave optical parametric generator providing powerful femtosecond pulses at 1 kHz. In both cases, ZnGeP[sub 2] samples with reduced anomalous absorption were used. The parametric fluorescence in these 2-mm thin ZnGeP[sub 2] samples was studied with near infrared pumping and the optimum pump wavelength established lies between 1.9 and 2.1 μm. The femtosecond signal and idler pulses generated could be tuned between 2.5 and 12 μm at a maximum single pass internal conversion efficiency of 2.5%. [ABSTRACT FROM AUTHOR]

Abstract. The photodissociation dynamics of HNO[sub 3] in the electronic S[sub 3] (2[sup 1]A') state leading to the fragments OH and NO[sub 2] was investigated in real time. HNO[sub 3] was prepared either in a fluorescence cell at room temperature (LIF probing of OH) or rotationally cold in a molecular beam (probing of NO[sub 2] by three-photon ionization). A 2 [sup 1]A' lifetime of 60-80 fs could be obtained from the experimental results, indicating essentially barrierless dissociation. In addition, secondary dissociation of internally excited nascent fragments NO~ leading to products NO(X [sup 2]PI) and O([sup 3]P) with a characteristic dissociation time of 2.3 ps was observed. This time is surprisingly long when compared with dissociation lifetimes of NO[sub 2] from the literature, obtained after direct photoexcitation. The discrepancy is explained by differences in the preparation conditions of the dissociative state of NO[sub 2]. [ABSTRACT FROM AUTHOR]

We demonstrate direct access to the 4.8-9 μm spectral region with 800 nm, 1 kHz pumping of a femtosecond optical parametric amplifier based on the wide-gap wurtzite-type LiInS[sub 2]. LiInS[sub 2] did not exhibit two-photon absorption at 800 nm and seems applicable at this pump wavelength with intensities of the order of 100 GW/cm[sup 2] for down-conversion of high energy ultrashort pulses up to its mid-IR edge at approx. 12 μm. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Using the efficient nonlinear conversion scheme which was recently developed in our group [M. Beutler, M. Ghotbi, F. Noack, and I. V. Hertel, Opt. Lett. 134, 1491 (2010); M. Ghotbi, M. Beutler, and F. Noack, ibid 35, 3492 (2010)] to provide intense sub-50 fs vacuum ultraviolet laser pulses we have performed the first real time study of ultrafast, photo-induced dynamics in the electronically excited Ã-state of water clusters (H2O)n and (D2O)n , n = 2-10. Three relevant time scales, 1.8-2.5, 10-30, and 50-150 fs, can be distinguished which-guided by the available theoretical results-are attributed to H (D)-ejection, OH (OD) dissociation, and a nonadiabatic transition through a conical intersection, respectively. While a direct quantitative comparison is only very preliminary, the present results provide a crucial test for future modeling of excited state dynamics in water clusters, and should help to unravel some of the many still unresolved puzzles about water. [ABSTRACT FROM AUTHOR]

Abstract. Frequency doubling the output of a high-power femtosecond Cr:forsterite regenerative amplifier with > 50% conversion efficiency in a temperature-tuned noncritically phase-matched LBO crystal produces femtosecond pulses of > 100 micro J energy in the visible range near 625 nm at a pulse duration of about 200 fs or > 65 micro J at < 170 fs. [ABSTRACT FROM AUTHOR]

Ammonia dimers and trimers are studied in a femtosecond pump probe experiment. The pump laser (6.2 eV) excites the cluster into the à state which is ionized either by 4.6 eV or by 3.1 eV probe photons. Characteristic differences are explained in terms of a kinetic model involving an internal protonated neutral excited state as an intermediate. [ABSTRACT FROM AUTHOR]

Presents a study which converted the tuning range of a femtosecond titanium:sapphire laser amplifier through cascaded second-order nonlinear frequency conversion processes. Experimental arrangement and harmonics generation; Optical parametric generation and amplification; Conclusion.

The synthesis of 2,4,6-triphenylphosphinine has been revisited and a general protocol for the preparation of such low-coordinate phosphorus compounds in good to excellent yields could be established. This allows to investigate several aspects of the chemistry of 2,4,6-triarylphosphinine, such as the reaction with in situ generated benzyne to give 2,4,6-triphenylphosphabarrelene. The corresponding 2,4,6-triphenylphosphabarrelene-selenide could be characterized crystallographically for the first time and the structural and electronic properties of this cage-compound in comparison to classical triarylphosphines could be evaluated. Moreover, [(L)W(CO)5)] complexes of both 2,4,6-triphenylphosphinine and 2,4,6-triphenylphosphabarrelene were prepared and characterized by means of X-ray crystallography. This allowed for the first time a direct structural comparison of these related phosphorus compounds, coordinated to the same metal fragment. [ABSTRACT FROM AUTHOR]

Background: Recent studies suggested p53 mutations as a prognostic factor. Tumors of the esophagus and gastroesophageal (GE) junction show raising incidence with a general poor prognosis. Methods: p53 mutational spectra in 103 patients (68 squamous cell carcinoma/SCC and 35 adenocarcinoma/AC) were compared to clinical and pathologic data. Results and Conclusions: p53 mutations were found in 26 of 68 SSC (38.2%) and in 12 of 35 AC (34.5%). We only found G > T transversions in smokers with SCC. The survival of patients was not affected by p53 mutational status. In our study, the frequency and mutational spectrum of mutant p53 is similar in both histological types without prognostic relevance. [ABSTRACT FROM AUTHOR]

Abstract: The nonlinear refractive index of the monoclinic biaxial nonlinear crystal BiB3O6 (BIBO) was measured at 1064nm for light polarization along the three principal optical axes using the single-beam z-scan technique. Strong anisotropy was observed with n 2 values about two-times larger for polarization parallel to the Z-axis in comparison to the X-axis. BIBO exhibits lower nonlinear refractive index than KTP although its effective nonlinearity is larger. [Copyright &y& Elsevier]

Background: Mutations in NOD2, a putative intracellular receptor for bacterial peptidoglycans, are associated with a subset of Crohn's disease but the molecular mechanism linking this protein with the disease pathogenesis remains unclear. Human a defensins (HD-5 and HD-6) are antibiotic effector molecules predominantly expressed in Paneth cells of the ileum. Paneth cells also express NOD2. To address the hypothesis that the function of NOD2 may affect expression of Paneth cell defensins, we compared their expression levels with respect to NOD2 mutations in Crohn's disease. Methods: Forty five Crohn's disease patients (24 with NOD2 mutations, 21 with wild-type NOD2) and 12 controls were studied. Real time reverse transcription-polymerase chain reaction was performed with mucosal mRNA for HD-5, HD-6, lysozyme, secretory phospholipase A2 (sPLA2), tumour necrosis factor α, interleukin 8, and human hypoxanthine phosphoribosyltransferase (housekeeping gene). Immunohistochemistry with anti-HD-5 and histological Paneth cell staining were performed in 10 patients with NOD2 mutations or wild-type genotypes. Results: Ileal expression of HD-5 and HD-6, but not sPLA2 or lysozyme, were diminished in affected ileum, and the decrease was significantly more pronounced in patients with NOD2 mutations. In the colon, HD-5, HD-6, and sPLA2 were increased during inflammation in wild-type but not in NOD2 mutated patients. In both the colon and ileum, proinflammatory cytokines and lysozyme were unaffected by NOD2 status. Immunohistochemistry identified Paneth cells as the sole source of HD-5. Conclusion: As alpha defensins are important in the mucosal antibacterial barrier, their diminished expression may explain, in part, the bacterial induced mucosal inflammation and ileal involvement of Crohn's disease, especially in the case of NOD2 mutations. [ABSTRACT FROM AUTHOR]

Combined laser and synchrotron radiation (SR) photoelectron spectroscopy with a temporal resolution of 60 ps has been applied to study the relaxation of the surface photovoltage (SPV) after laser pulse excitation for a SiO2/Si(1 0 0) interface. For zero time delay between laser and SR pulses the Si 2p core level exhibits an initial spectral shift of 300 meV which relaxes non-exponentially to about 100 meV after 800 ns. The relaxation of the SPV can be modeled using a self-decelerating carrier relaxation based on a thermionic emission model. [Copyright &y& Elsevier]

Abstract. Nonthermal in vitro ablation of bovine neural tissue by using laser-induced optical breakdown generated by ultrashort laser pulses, with durations from 100 fs to 35ps and pulse energies of up to 165 micro J, has been investigated. The experiments were performed at wavelengths ranging from 630 to 1053 nm by using a femtosecond Ti:Sapphire laser, a femtosecond dye laser, and a picosecond Nd:YLF laser system. Tissue ablations have been achieved by focusing the laser beam on the surface of the tissue, to a spot diameter of 5-20 micro m, resulting in the generation of a microplasma. Laser pulses from the Ti:Sapphire laser with 140 fs duration showed a two times higher efficiency of ablation than the longer 30 ps pulses from a Nd:YLF laser with an identical pulse energy. At pulse energies of 140 micro J, single pass excisions deeper than 200 micro m were generated by the 140 fs pulses. In addition, the fluence at threshold of the ablation was found to be reduced for shorter pulse durations. For 3 ps laser pulses at 630 nm, we measured the fluence at threshold to be about 5.3 J/cm[sup 2]; for 100 fs pulses from the same laser the experimental threshold was at 1.5 J/cm[sup 2]. Histopathological examinations and scanning electron micrographs confirm the high quality of the excisions. No sign of significant thermal damage was observed. [ABSTRACT FROM AUTHOR]

The formation of protonated and unprotonated ammonia cluster ions is studied by femtosecond two colour two photon pump-probe techniques applied to (NH) and (ND) clusters with n up to 8. The fourth harmonic (∼ 200 nm, 6.2 eV, 160 fs) of a Ti: Sapphire laser pulse is used to excite the clusters in a state corresponding to the à state of NH while the third harmonic (267 nm, 4.65 eV) is used for the subsequent ionisation step. Employing a combination of the optical Bloch equations for the excitation process and rate equations for the cluster dynamics we calibrate the zero time delay and carefully analyse the time dependence of the pump-probe signal. Several distinct intermediate steps in the time evolution can be distinguished, having characteristic time constants ranging from 40 fs to over 100 ps. They are discussed in a consistent scheme for the excitation, ionisation and protonation dynamics, accounting also for characteristic differences observed between deuterated and undeuterated species. A particularly remarkable time dependence of the homogeneous (NH) cluster ion signal is interpreted as a fingerprint of internally protonated neutral precursors of the type NHNHNH. [ABSTRACT FROM AUTHOR]

We have investigated the morphology of CaF[sub 2] (111) irradiated by 780 nm laser pulses of varying pulse width (200 fs-8 ns) with fluences above the damage threshold. Large differences can be observed which we relate to the mechanisms and dynamics of defect production in this wide band gap material. The best defined and most controllable ablation is obtained for laser pulse widths of a few picoseconds. For nanosecond and femtosecond pulses strong fracturing of the crystal is observed with damage outside the laser irradiated zone. This has a thermal origin for nanosecond pulses but a non-thermal origin for pulse widths below approximately 1 ps. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented which discusses the prenatal imaging and postnatal pathologic work-up in a case of a 29-year-old woman, gravida 2 para 1, who was diagnosed with placental mesenchymal dysplasia (PMD) and fetal hepatic hamartoma.

A letter to the editor is presented in response to the article "Helminths as governors of inflammatory bowel disease" which was published in a previous issue of the periodical.