Attosecond nonlinear polarization and light-matter energy transfer in solids.

Electric-field-induced charge separation (polarization) is the most fundamental manifestation of the interaction of light with matter and a phenomenon of great technological relevance. Nonlinear optical polarization produces coherent radiation in spectral ranges inaccessible by lasers and constitutes the key to ultimate-speed signal manipulation. Terahertz techniques have provided experimental access to this important observable up to frequencies of several terahertz. Here we demonstrate that attosecond metrology extends the resolution to petahertz frequencies of visible light. Attosecond polarization spectroscopy allows measurement of the response of the electronic system of silica to strong (more than one volt per ångström) few-cycle optical (about 750 nanometres) fields. Our proof-of-concept study provides time-resolved insight into the attosecond nonlinear polarization and the light-matter energy transfer dynamics behind the optical Kerr effect and multi-photon absorption. Timing the nonlinear polarization relative to the driving laser electric field with sub-30-attosecond accuracy yields direct quantitative access to both the reversible and irreversible energy exchange between visible-infrared light and electrons. Quantitative determination of dissipation within a signal manipulation cycle of only a few femtoseconds duration (by measurement and ab initio calculation) reveals the feasibility of dielectric optical switching at clock rates above 100 terahertz. The observed sub-femtosecond rise of energy transfer from the field to the material (for a peak electric field strength exceeding 2.5 volts per ångström) in turn indicates the viability of petahertz-bandwidth metrology with a solid-state device.

Anchorage value of surgical titanium screws in orthodontic tooth movement.

The aim of this study was to evaluate the clinical stability and anchorage value of titanium screws in orthodontic tooth movement. Nine patients, who needed maximum anchorage for canine retraction, were selected. Records of 10 patients with similar malocclusions who had received conventional treatment were used as controls. In the maxilla and mandible 27 mini-screws, diameter 2mm and length 9 or 11 mm, were used. At the end of the first stage of orthodontic treatment the first premolar teeth were extracted after taking a lateral cephalometric radiograph. After 1 week, a retraction force of 180 g was applied to the canines. The second cephalometric X-rays were taken and evaluated after the completion of canine retraction (mean duration of 23.2 weeks). Results were analysed using Fisher Exact, Wilcoxon signed ranks and paired t-tests. Displacement of the first molars and screws before and after treatment showed no significant changes in either the vertical or horizontal plane. The first molar movements in the study and control groups were only significant in the antero-posterior plane in both maxilla and mandible. Of the 9 screws in maxilla and 18 screws in mandible, 2 and 3 screws showed clinical failure, respectively. The failed screws were replaced by other screws that withstood the applied force until the end of treatment. In conclusion, titanium screws can be used reliably as a form of anchorage.

The use of index of orthodontic treatment need in an Iranian population.

This study aims to evaluate the need for orthodontic treatment between 11 and 14 year old school children in Shiraz. A sample of 2000 students consisting of 1200 boys and 800 girls from various parts of the city was selected. The index of orthodontic treatment need (IOTN) was used by two calibrated examiners. The data was recorded in questionnaires to assess dental health components (DHC). Aesthetic components (AC) were evaluated both by students (AC) and examiners (ACE). The results for DHC of IOTN were: 18.39% of population showed severe and very severe need for treatment, 25.8% were in border line category, 48.1% had a slight need and the percentage for no need to treatment was 7.63%. In evaluating AC, 91.93% were in no need or little need, 3.91% in moderate need and 4.11% in great need to treatment group. Where as ACE resulted in: 91.31% no need and little need, 2.44% moderate need and 6.21% great need to treatment. There was a slight statistical correlation (0.54) between AC and ACE, but a very weak correlation between DHC and AC was observed. According to DHC, boys showed more need for treatment than girls (P=0.001). Grade 8 showed the most percentage in great need category in both AC and ACE (3.41% of 4.11% and 5.74% of 6.21%, respectively). The results indicate that the need for orthodontic treatment was less than other studies and most of the students were in the category of little need for treatment.

[Mechanical staplers in orthotopic ileal neo-bladder using the Studer and Zingg method: our experience]. / Le suturatrici meccaniche nella neovescica ileale ortotopica sec. Studer e Zingg: nostra esperienza.

Detubularized orthotopic low-pressure bladder substitute following radical cystoprostatectomy allows micturition per urethram and urinary continence. We performed the Studer and Zingg procedure with ileal reservoirs in 26 bladder cancer patients, using staplers in 11 cases. A reduced operating time and a low postoperative complication rate were observed in these cases. Furthermore, functional results were comparable to those obtained with manual sutures and lithiasis was never observed.

[Nerve-sparing cystectomy and ileal bladder substitution]. / Cistectomia nerve-sparing e neovescica ileale di sostituzione.

Nerve-sparing techniques and bladder substitution following radical cystectomy allow today to obviate functional sequelae once registered in this type of surgery. Intraoperative identification of the pelvic plexus, which provides autonomic innervation to the corpora cavernosa, is necessary to preserve sexual function. Ileal orthotopic bladder substitution with preservation of the distal urethral sphincter assures a micturition per urethram and the urinary continence. The Authors report their experience with the Studer and Zingg procedure (ileal orthotopic bladder reservoir) performed in 26 cases. Results, technique, complications, and long-term evaluation are stressed.

Orthotopic ileal neobladder in female patients after radical cystectomy: 2-year experience.

We describe a surgical technique to conserve urinary continence in 7 women who underwent radical cystectomy with construction of an orthotopic ileal neobladder for infiltrating bladder carcinoma. The selection of the patients and the surgical procedure to preserve the anatomical and functional integrity of the female urethra are described. Followup ranged from 7 to 28 months. There were no postoperative deaths or serious clinical complications. The urinary continence rate was 100% during the day and 71% at night with micturition at regular 3-hour intervals. The vesical capacity varied from 250 to 400 cc and pressure at maximum capacity from 10 to 25 cm. water. Urinary flow was satisfactory and the urethral pressure profile showed a normal sphincteric mechanism at rest. Two patients died of metastases at 14 and 8 months postoperatively, and 5 are alive and disease-free. We believe that these results confirm the possibility of obtaining micturition in women via the urethra following radical cystectomy.

Ureteral anastomosis in the orthotopic ileal neobladder: comparison of 2 techniques.

PURPOSE: The functional results and complications of 2 different ureteroileal anastomoses were evaluated in patients with bladder cancer undergoing radical cystectomy and orthotopic ileal bladder substitution. MATERIALS AND METHODS: Between 1989 and 1995, 102 patients underwent creation of a low pressure neobladder. In the first 50 cases the ureteroileal anastomosis was created with a split-cuff nipple technique as an additional antireflux mechanism. In the next 52 cases the ureteroileal anastomoses were constructed via the direct end-to-side technique counting on the antireflux protection of the afferent tubular limb. RESULTS: Stenosis occurred in 7 of the 100 ureters (6 patients) treated with the split-cuff nipple technique and 7 of 104 treated with a direct end-to-side anastomosis. This complication occurred more commonly in the left ureter (11 of 14 patients). Reflux was noted at cystography in 10 cases with the split-cuff nipple method and 12 with end-to-side anastomoses, and was symptomatic in only 3 patients. Four ureteral strictures were treated successfully with primary open repair. Percutaneous dilation and stenting were performed for 8 ureteral strictures: 2 cases were successful, 3 failed and 3 are unresolved. CONCLUSIONS: We observed no differences between the antireflux split-cuff and end-to-side anastomoses with regard to stricture formation or ureteral reflux. Therefore, we do not believe that there is a need to create antireflux ureteral anastomoses due to the tubular afferent ileal segment and given that the reflux is asymptomatic in most patients. Strictures may be treated with percutaneous balloon dilation and stenting but open repair appeared to be more effective.

Lower urinary tract reconstruction following cystectomy: experience and results in 96 patients using the orthotopic ileal bladder substitution of Studer et al.

Between 1989 and 1993 96 patients (89 males and 7 females) affected with invasive neoplasms of the bladder underwent surgery consisting of the creation of an orthotopic ileal neobladder according to Studer et al., after radical cystectomy. Patient selection and details of the surgical procedure are described. An accurate follow-up of 3-60 months (mean: 28 months) is presented. There have been 6 perioperative deaths (6.2%) and 11 early complications, all directly related to the neobladder and requiring reoperation in 6 cases (6.2%). Late complications required rehospitalization in 23 cases (23.9%) and a second reoperation was necessary in 10 (10.4%). The urodynamic tests show that the neobladder assumes an average capacity at about 330 cm3 after 1 year. Pressure at maximum capacity decreases in time and ranges from 10 to 20 cm H2O at 2 years. After 1 year, the complete urinary continence rate by day is 97% and the stress incontinence rate is 22%. Night-time continence, instead, increases to 74% after 1 year and to 83% after 2 years. In female patients, the functional results were satisfactory thanks to careful patient selection and to the surgical procedure adopted. Twenty-four patients had disease progression; 17 of these patients with locally advanced neoplasms died. The authors believe that the orthotopic ileal continent reservoir can be a satisfactory solution after cystectomy for bladder cancer, offering the patients a better quality of life compared to other urinary diversions both in male and female patients.