Dental caries-related quality of life and socioeconomic status of preschool children, Bauru, SP

AIM: To evaluate oral health-related quality of life of preschool children of Bauru, State of São Paulo, Brazil, and associate it with socioeconomic profile of households. METHODS: The sample consisted of 229 preschool children between 3 and 5 years and the dmft (decayed, missing due to caries, filled teeth) index was adopted for assessment children's dental caries in accordance with the standards recommended by the World Health Organization. Questionnaires were used for evaluation oral health-related quality of life (Early Childhood Oral Health Impact Scale) and socioeconomic profile of parents or guardians of the preschool children. Statistical analysis was performed descriptively by relative and absolute frequencies and by Spearman's correlation and Kruskal-Wallis test (p <0.05). RESULTS: A dmft of 1.65 (± 2.87) and a Sic Index 4.88 (± 3.20) were found, indicating the polarization of dental caries in the studied group. It was verified low influence of oral health on quality of life of the children examined. With respect to socioeconomic classification, 66.38% of families were in the lower middle class. Linear and statistically significant correlation was found between dmft and oral health-related quality of life for the overall score and domains of the questionnaire (p<0.001). CONCLUSIONS: It was found low influence of oral health on quality of life of the preschool children and the assessment of socioeconomic conditions of the children's families may guide practices aiming to reducing inequalities in the distribution of dental caries in the population

Performance of pavement crack sealants in cold urban conditions

Twelve bituminous hot-pour crack sealants were evaluated over four years in temperatures ranging from?40\ub0C to +40\ub0C. Each sealant was evaluated over 900 linear meters of transverse and longitudinal routs of 12 712 mm2, 19 7 19 mm2, and 40 7 10 mm2 (width 7 depth). Results show that sealant source, rout size, and routorientation affected sealant performance, i.e., debonding and pull-out levels. Debonding levels were 0?50% and pull-out levels 0?30%. Sealant failure was proportional to rout width; it was lowest in 12 mm wide routs and highest in 40 mm wide routs. This result is attributed to the proportional exposure of sealants to slow moving traffic. The increase of sealant failure over time was also found to be nonlinear. Three stages were identified in the failure?time plot. In stage 1, failure is rapid; in stage 2, it plateaus; and in stage 3, it increases again. Failure in stage 1 is thought to be related mainly to a weak sealant ? asphalt concrete interface, whereas that in stage 3 is thought to be related to sealant weathering and stiffening. It was also found that standard test results correlate poorly with field performance.Douze mastics bitumineux ont \ue9t\ue9 \ue9valu\ue9s sur une p\ue9riode de quatre ans sous des temp\ue9ratures allant de?40\ub0C \ue0 +40\ub0C. Chacun a \ue9t\ue9 \ue9valu\ue9 sur 900 m\ue8tres lin\ue9aires de fraisures transversales ou longitudinales de 12 7 12 mm2, 19 7 19 mm2 et 40 7 10 mm2 (largeur 7 profondeur). Les r\ue9sultats d\ue9montrent que la provenance du mastic, la taille de la fraisure et son orientation ont eu un effet sur la performance du produit, c.-\ue0-d. sur les niveaux de d\ue9collement et d'arrachement. Les niveaux de d\ue9collement variaient entre 0 et 50% et les niveaux d'arrachement, entre 0 et 30%. La performance des mastics \ue9tait inversement proportionnelle \ue0 la largeur des fraisures; elle \ue9tait meilleure dans les fraisures de 12 mm de largeur que dans celles de 40 mm. Le plus grand taux de rupture des mastics de 40 mm correspond \ue0 leur exposition \ue0 la circulation. On a aussi constat\ue9 que l'aggravation de la rupture des mastics dans le temps \ue9tait non lin\ue9aire. Trois stades ont \ue9t\ue9 mis en \ue9vidence dans le graphique rupture?temps. Au premier stade, la rupture est rapide, au deuxi\ue8me elle se stabilise et au troisi\ue8me, elle reprend. On croit que la rupture observ\ue9e au premier stade est attribuable en premier lieu \ue0 la faiblesse de l'interface mastic-b\ue9ton bitumineux, alors que celle constat\ue9e au troisi\ue8me stade serait due au vieillissement et au durcissement du mastic. On a aussi constat\ue9 que les r\ue9sultats des essais normalis\ue9s concordaient mal avec la performance en service.Peer reviewed: YesNRC publication: Ye

Adaptive compression of intense 250-nm-bandwidth laser pulses

Self-phase modulation produced by propagation of a 50-fs laser pulse in a hollow-core fiber capillary filled with argon gas was used to broaden the bandwidth from 30 nm to 250 nm. A subsequent compressor utilizing a pair of gratings and cylindrical optics compressed the pulse to 12.5 fs. A liquid-crystal spatial light modulator (SLM) was placed in the compressor, and an evolutionary algorithm based on feedback from the second-harmonic signal was used to control the SLM and optimize the pulse duration. The algorithm increased the second-harmonic signal by a factor of two, indicating that it has substantially improved on the 12.5-fs pulse duration.Peer reviewed: YesNRC publication: Ye

All-optical reconstruction of crystal band structure

The band structure of matter determines its properties. In solids, it is typically mapped with angle-resolved photoemission spectroscopy, in which the momentum and the energy of incoherent electrons are independently measured. Sometimes, however, photoelectrons are difficult or impossible to detect. Here we demonstrate an all-optical technique to reconstruct momentum-dependent band gaps by exploiting the coherent motion of electron-hole pairs driven by intense midinfrared femtosecond laser pulses. Applying the method to experimental data for a semiconductor ZnO crystal, we identify the split-off valence band as making the greatest contribution to tunneling to the conduction band. Our new band structure measurement technique is intrinsically bulk sensitive, does not require a vacuum, and has high temporal resolution, making it suitable to study reactions at ambient conditions, matter under extreme pressures, and ultrafast transient modifications to band structures.Peer reviewed: YesNRC publication: Ye

Observation of Cooper minimum in krypton using high harmonic spectroscopy

High harmonic spectroscopy utilizes the methods of attosecond science to study electronic properties of atoms and molecules. We use a 1.8 \u3bcm 11 fs laser source to generate high harmonic spectra beyond 150 eV. The Cooper minimum in krypton is clearly visible in these spectra, and would otherwise be difficult to observe with 800 nm laser sources. We relate the shape of the spectrum to the photoionization cross section of krypton.Peer reviewed: YesNRC publication: Ye

High-energy sub-picosecond pulse generation from 3 to 20 \ub5m

We have produced sub-picosecond pulses in the wavelength range 3\ufffd20 \ufffdm with energies as high as 2 \ufffdJ, through difference-frequency mixing in the crystal GaSe. Input beams for the non-linear mixing process came from either a regenerative amplifier operating in two-color mode, due to the spectral shaping of its injection beam, or an optical parametric amplifier (OPA). The first method was straightforward to implement and provided easy access to the wavelength range 10\ufffd20 \ufffdm. The intermediate OPA stage, though technically more involved, allowed higher input beam irradiances and resulted in shorter duration MIR pulses, greater conversion efficiency and access to the MIR region between 3 and 10 \ufffdm.Peer reviewed: YesNRC publication: Ye

Revealing the giant resonance in Xe via HHG with sub-two cycle 1.8 \u3bcm laser pulses

Recent advances in optical parametric amplification (OPA) based few-cycle pulse generation at 1.8 \u3bcm wavelength led to the discovery of multi-electron correlation effects in high harmonic generation (HHG), in particular the giant resonance in Xe. The novel scheme for sub-two cycle pulse generation rests upon nonlinear propagation of OPA pulses in a hollow-core fiber and subsequent compression solely by linear propagation through Fused Silica which exhibits anomalous dispersion [1]. The spectral phase introduced by self-phase modulation and self-steepening cancels material dispersion up to third order to provide an ideal laser source for HHG in gases with low ionization potential. \ua9 2011 IEEE.Peer reviewed: YesNRC publication: Ye

Shakeup excitation during optical tunnel ionization

Shakeup of a two-electron system is investigated in the strong infrared laser field limit, both theoretically and experimentally. During tunnel ionization the electron shakes up a second electron to an excited bound state. Theoretically, a complete analytical theory of shakeup in intense laser fields is developed. We predict that shakeup produces one excited \u3c3u D2 + state in 48 105 ionization events. Shakeup is measured experimentally by using the molecular clock provided by the internuclear motion. The number of measured events is found to be in excellent agreement with theory.Peer reviewed: YesNRC publication: Ye

High harmonic generation with long-wavelength few-cycle laser pulses

We report the extension of hollow-core fibre pulse compression to longer wavelengths. High-energy multi-cycle infrared pulses are generated via optical parametric amplification and subsequently broadened in the fibre. 2.5-cycle pulses at the Signal wavelength (1.4 \ub5m) and 1.6-cycle pulses at the Idler wavelength (1.8 \ub5m) in the sub-millijoule regime have been generated. New compression schemes can be applied at 1.8 \ub5m and beyond. In this manner, 1.6-cycle carrier envelope phase stable pulses were generated by linear propagation in the anomalous dispersion regime of bulk glass which surprisingly enables compression below its third-order dispersion limit. Furthermore, a dispersion-free way of controlling the carrier envelope phase is demonstrated. Moreover, we experimentally confirm the increase in high-harmonic cut-off energy with driving laser wavelength and demonstrate the beneficial effect of few-cycle pulses which enable higher saturation intensities on target compared to multi-cycle pulses. It will be an ideal tool for future synthesis of isolated attosecond pulses in the sub-keV regime. With this laser source, we revealed for the first time multi-electron effects in high harmonic generation in xenon.Peer reviewed: YesNRC publication: Ye

High harmonic generation in ethylene with infrared pulses

We produce harmonics in the molecule ethylene (C\u2082H\u2084) with two different wavelengths and three pulse durations. Due to the low ionization potential (Ip = 10.5 eV) of C\u2082H\u2084, longer wavelengths are needed to extend the maximum photon energy produced. Our results show that regardless of the strong dependence of the efficiency of the harmonic generation process with wavelength, at 1820 nm the cutoff observed is larger than that obtained with 800 nm, 15 fs pulses. We obtain harmonics with energies exceeding 70 eV at 9.0 x 10\ub9\ub3 W/cm\ub2 with a 73 fs 1820 nm pulse. Under these circumstances, the limiting factor for the further extension of the cutoff seems to be the phoionization cross section of the molecule.Peer reviewed: YesNRC publication: Ye