Concurrence of monoenergetic electron beams and bright X-rays from an evolving laser-plasma bubble.

Desktop laser plasma acceleration has proven to be able to generate gigaelectronvolt-level quasi-monoenergetic electron beams. Moreover, such electron beams can oscillate transversely (wiggling motion) in the laser-produced plasma bubble/channel and emit collimated ultrashort X-ray flashes known as betatron radiation with photon energy ranging from kiloelectronvolts to megaelectronvolts. This implies that usually one cannot obtain bright betatron X-rays and high-quality electron beams with low emittance and small energy spread simultaneously in the same accelerating wave bucket. Here, we report the first (to our knowledge) experimental observation of two distinct electron bunches in a single laser shot, one featured with quasi-monoenergetic spectrum and another with continuous spectrum along with large emittance. The latter is able to generate high-flux betatron X-rays. Such is observed only when the laser self-guiding is extended over 4 mm at a fixed plasma density (4 × 10(18) cm(-3)). Numerical simulation reveals that two bunches of electrons are injected at different stages due to the bubble evolution. The first bunch is injected at the beginning to form a stable quasi-monoenergetic electron beam, whereas the second one is injected later due to the oscillation of the bubble size as a result of the change of the laser spot size during the propagation. Due to the inherent temporal synchronization, this unique electron-photon source can be ideal for pump-probe applications with femtosecond time resolution.

Enhanced single-stage laser-driven electron acceleration by self-controlled ionization injection.

We report on overall enhancement of a single-stage laser wakefield acceleration (LWFA) using the ionization injection in a mixture of 0.3% nitrogen gas in 99.7% helium gas. Upon the interaction of 30-TW, 30-fs laser pulses with a gas jet of the above gas mixture, >300 MeV electron beams were generated at a helium plasma densities of 3.3-8.5 × 10(18) cm(-3). Compared with the uncontrolled electron self-injection in pure helium gas jet, the ionization injection process due to the presence of ultra-low nitrogen concentrations appears to be self-controlled; it has led to the generation of electron beams with higher energies, higher charge, lower density threshold for trapping, and a narrower energy spread without dark current (low energy electrons) or multiple bunches. It is foreseen that further optimization of such a scheme is expected to bring the electron beam energy-spread down to 1%, making them suitable for driving ultra-compact free-electron lasers.

A laser wakefield acceleration facility using SG-II petawatt laser system.

Laser wakefield acceleration (LWFA) using PW-class laser pulses generally requires cm-scale laser-plasma interaction Rayleigh length, which can be realized by focusing such pulses inside a long underdense plasma with a large f-number focusing optic. Here, we present a new PW-based LWFA instrument at the SG-II 5 PW laser facility, which employs f/23 focusing. The setup also adapted an online probing of the plasma density via Nomarski interferometry using a probe laser beam having 30 fs pulse duration. By focusing 1-PW, 30-fs laser pulses down to a focal spot of 230 µm, the peak laser intensity reached a mild-relativistic level of 2.6 × 1018 W/cm2, a level modest for standard LWFA experiments. Despite the large aspect ratio of >25:1 (transverse to longitudinal dimensions) of the laser pulse, electron beams were observed in our experiment only when the laser pulse experienced relativistic self-focusing at high gas-pressure thresholds, corresponding to plasma densities higher than 3 × 1018 cm-3.

A laser-plasma accelerator driven by two-color relativistic femtosecond laser pulses.

A typical laser-plasma accelerator (LPA) is driven by a single, ultrarelativistic laser pulse from terawatt- or petawatt-class lasers. Recently, there has been some theoretical work on the use of copropagating two-color laser pulses (CTLP) for LPA research. Here, we demonstrate the first LPA driven by CTLP where we observed substantial electron energy enhancements. Those results have been further confirmed in a practical application, where the electrons are used in a bremsstrahlung-based positron generation configuration, which led to a considerable boost in the positron energy as well. Numerical simulations suggest that the trailing second harmonic relativistic laser pulse is capable of sustaining the acceleration structure for much longer distances after the preceding fundamental pulse is depleted in the plasma. Therefore, our work confirms the merits of driving LPAs by two-color pulses and paves the way toward a downsizing of LPAs, making their potential applications in science and technology extremely attractive and affordable.

Laparoscopically assisted balloon vaginoplasty for management of vaginal aplasia.

OBJECTIVE: To report the intra-operative and post-operative results of laparoscopically assisted balloon vaginoplasty, a new technique for management of vaginal aplasia. METHODS: Eight women with vaginal aplasia due to Mullerian agenesis who were referred for apareunia, dyspareunia. All had a poor penetration score and sexual satisfaction score. A Foley's catheter was laparoscopically inserted in the space between the urethra and rectum. Gradual traction and distension were used to create a neovagina. Outcomes measured were intra-operative complications, post-operative complications, length of the neovagina and post-operative complications and sexual satisfaction score in both partners. RESULTS: Mean operative time was 25.5+/-5.5 min. No operative complications were recorded. Pain scores ranged from zero to 30 points at rest and from 30 to 60 points during dressing, traction and distension. Penetration and satisfaction scores increased significantly after the operation. CONCLUSIONS: Balloon vaginoplasty is a simple, safe and satisfactory technique for management of blind vagina.

Bearing capacity of shell strip footing on reinforced sand.

In this paper, the ultimate load capacities of shell foundations on unreinforced and reinforced sand were determined by laboratory model tests. A series of loading tests were carried out on model shell footing with and without single layer of reinforcement. The tests were done for shell foundation at different shell embedment depth and subgrade density. The results were compared with those for flat foundations without reinforcement. The model test results were verified using finite element analysis using program PLAXIS. The experimental studies indicated that, the ultimate load capacity of shell footing on reinforced subgrade is higher than those on unreinforced cases and the load settlement curves were significantly modified. The shell foundation over reinforced subgrade can be considered a good method to increase the effective depth of the foundation and decrease the resulting settlement. Also the rupture surface of shell reinforced system was significantly deeper than both normal footing and shell footing without reinforcement. The numerical analysis helps in understanding the deformation behavior of the studied systems and identifies the failure surface of reinforced shell footing.

Hematological and biochemical investigations on the effect of vitamin E and C on Oreochromis niloticus exposed to zinc oxide nanoparticles.

This study was carried out to determine the LC50 of zinc oxide nanoparticles (ZnONPs) on Oreochromis niloticus and to investigate the effect of vitamin E and C on hematological and biochemical alterations induced by two sublethal concentrations (1 and 2 mg/L) of ZnONPs. One hundred and eighty fish were used for studying the lethal concentrations of ZnONPs. For sublethal study two hundred and twenty-five males of O. niloticus were equally divided into five groups, control, the second and the third were treated with 1 and 2 mg/L ZnONPs respectively. The fourth and fifth were exposed to the same concentrations of ZnONPs plus vitamins E and C. The results revealed that the 96 h LC50 of ZnONPs was 3.1 ± 0.4 mg/L. The sublethal study revealed the presence of normocytic normochromic anemia in groups (2, 3 and 5) along the experiment period. The 4th group showed normocytic normochromic anemia at the 7th day and microcytic hypochromic anemia at the 15th day. Leukocytosis, heterophilia, lymphopenia and monocytopenia were recorded at the 7th day in all treated groups compared with the normal control. At the 15th day heteropenia, lymphopenia and monocytopenia were reported in all treated groups. A significant increase in the serum levels of alkaline phosphatase, aminotransferases, urea, creatinine and erythrocytic nuclear and morphological abnormalities along the experimental periods in all treated groups compared with the normal control. Serum total protein and albumin levels were significantly decreased at the same period in the same groups. Addition of vitamin E and C to the diet (groups 4 and 5) significantly improved all measured parameters compared with groups (2 and 3) which treated with ZnONPs only.

Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets.

An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

Secondary squamous cell carcinoma of the orbit.

OBJECTIVE: To evaluate the origin and biological behavior of secondary orbital squamous cell (SCC) and mucoepidermoid carcinoma. METHODS: A retrospective review of 30 consecutive patients with SCC and mucoepidermoid carcinoma of the orbit seen over a period of 8 years at a large ophthalmic hospital in Saudi Arabia. RESULTS: A total of 51 secondary orbital tumors were seen in the 8-year period from 1983 through 1991; 30 (60%) of the 51 cases were SCC. There were 16 male and 14 female patients, with an age range of 38 to 80 years and a mean age of 65 years. In 28 (93%) of the 30 patients, the tumor originated in the conjunctiva. Orbital involvement by conjunctival SCC was the most common cause of secondary orbital tumors encountered in patients older than 19 years. Four patients had concomitant paranasal sinus involvement, 4 patients exhibited intraocular invasion, and 2 others were found to have intracranial extension of the SCC. Six (20%) of the 28 patients developed regional lymph node metastases during the course of their illness. All patients were treated by orbital exenteration, with or without radiation therapy. Seven (23%) of the 28 patients died of their disease. CONCLUSIONS: Orbital SCC is an aggressive and life-threatening condition. Most cases result from secondary extension of conjunctival SCC, a common disease in Saudi Arabia. Several factors contribute to the aggressiveness of conjunctival SCC in this geographic location, including continual exposure to UV rays, chronic irritation, and genetic factors. Delay in presentation for treatment, inadequate initial resection of conjunctival lesions, and the aggressive mucoepidermoid carcinoma variant of SCC are also factors contributing to orbital invasion.

The epidemiology of schistosomiasis in Egypt: Qena governorate.

Qena is the southernmost governorate of Egypt included in the Epidemiology 1, 2, 3 national study. A probability sample selected 17,822 individuals from 2,950 households in 34 ezbas and 10 villages from a total rural target population of 1,731,252 (based on the most recent 1986 census of the population by the Egyptian Central Agency for Public Mobilization And Statistics). Parasitologic examination of urine and stool were made for Schistosoma haematobium and S. mansoni, respectively, and physical and ultrasound examinations were made on a 20% subsample. The overall estimated prevalence of S. haematobium was 4.8 +/- 0.7% (+/-SE) and geometric mean egg count (GMEC) was 7.0 ova per 10 ml of urine. Considerable variation in prevalence was observed between the villages and ezbas, ranging from 0.0% to 20%, with the smaller ezbas having a slightly higher overall prevalence. The age- and sex-specific patterns of S. haematobium showed typical peak prevalence in early adolescence, with males having a higher prevalence than females. A history of hematuria was associated with current infection (odds ratio = 3.6, 95% confidence interval = 2.32-5.63). Hepatomegaly and splenomegaly determined by physical examination present in 7.9% and 3.0%, respectively. Ultrasonography-determined hepatomegaly of the left liver lobe was found in 10.1%. Ultrasonography-detected hepatomegaly in both the left and right lobes increased in prevalence from approximately 5% in children to 15-20% in adults. The prevalence of ultrasonography-detected splenomegaly increased slightly with age. Grade III periportal fibrosis was detected in only 2 individuals in the sample. Bladder wall lesions and obstructive uropathy were also very infrequent. Other associations with these measures are given. Most villages and ezbas had an S. mansoni prevalence of less than 1%. The exception was Nag'a El-Sheikh Hamad, where the prevalence was 10.3 +/- 0.5% (GMEC = 57.4 +/- 2.6). Two other communities also had a prevalence >1% (Ezbet Sarhan and Kom Heitin).

Unilateral enophthalmos secondary to acquired hemilipodystrophy.

PURPOSE: To report a case of acquired hemilipodystrophy with ipsilateral enophthalmos. METHODS: Case report. We examined a 25-year-old woman who developed progressive unilateral enophthalmos secondary to fat atrophy on the corresponding left side of her body. RESULTS: Computed tomography confirmed that atrophy in the left orbit, loss of fat in the preorbital area, and partial loss of eyebrow cilia on the same side were present. A biopsy specimen from the left arm was consistent with lipodystrophy. The systemic examination and laboratory values were within normal limits. CONCLUSION: Although it is a rare condition, lipodystrophy may be a cause of unilateral enophthalmos.

Congenital generalized multicentric myofibromatosis with orbital involvement.

We studied a rare case of congenital myofibromatosis of the orbit as part of a generalized multicentric disease in a 5-month-old boy. The ultrasonographic and computed tomographic findings were those of a low-reflective, firm, vascularized, lesion with heterogeneous internal structure. The histopathologic findings showed vascular channels with large polygonal cells and transition toward myofibroblasts with interwoven collagen fiber bundles.

Orbital hemangiopericytoma: clinical and morphologic features.

PURPOSE: To report the clinical and histopathologic features of orbital hemangiopericytoma. METHOD: We review the clinical and histopathologic features in seven patients. RESULTS: Ultrasonography, computed tomography, and magnetic resonance imaging defined the location and extent of the tumor in each patient but did not disclose pathognomonic features for the specific diagnosis of hemangiopericytoma. The predominating histopathologic feature of each tumor was a mixed pattern of ovoid cells and sinusoidal space formations. Five patients showed mild to severe cellular atypia; three had obvious pleomorphism and increased number of abnormal mitotic figures. Tumor cells disclosed cytoplasmic reactivity for vimentin but in five cases were negative for other immunologic markers. Six patients received surgical treatment with an attempt for total removal of the tumor; one had biopsy and radiation therapy. In two patients, radiation therapy was given in addition to tumor removal with orbital exenterations. Three patients died with recurrent and metastatic disease, and four patients are alive without tumor for a follow-up period ranging from 3 to 9 years. CONCLUSIONS: Orbital hemangiopericytoma may behave as a malignant tumor, leading to local recurrence or metastasis, or both. Clinical and histopathologic findings should be considered jointly to evaluate the clinical course; histopathologic findings alone are not sufficient to predict the biologic behavior of this tumor.

Enchondromatosis and hemangioma (Maffucci's syndrome) with orbital involvement.

Maffucci's syndrome is a rare, congenital disease of unknown cause characterized by the development of multiple enchondromas and soft-tissue hemangiomas. We treated a 34-year-old man with Maffucci's syndrome, bilateral proptosis secondary to multiple intraorbital hemangiomas, corneal exposure secondary to a left facial nerve palsy, and multiple intra-abdominal tumors. The skeletal manifestations were not clinically apparent and were only discovered after a careful radiologic survey. Simultaneous bilateral orbital cavernous hemangiomas should alert the physician to the possibility of Maffucci's syndrome.

Standardized echographic-histopathologic correlations in liposarcoma.

A 57-year-old woman had metastatic liposarcoma of the left orbit that underwent transformation. The primary focus in the abdomen, resected in 1975, was a well-differentiated liposarcoma. Later metastases to the neck and orbit were poorly differentiated, pleomorphic, and highly anaplastic liposarcomas. The ultrasonographic and histopathologic correlations of the different stages of the tumor during the disease process were analyzed and compared. This patient's disease had echopathologic similarities to other orbital sarcomas and adult cavernous hemangiomas.

Ectopic (extradural) meningioma of the orbit: a report of two cases in children.

Meningiomas arising from the optic nerve or secondarily invading the orbit from the intracranial cavity are uncommonly encountered in children. Ectopic (extradural) meningiomas are exceedingly rare orbital tumors that do not originate from either the optic nerve or the intracranial meninges. We evaluated and treated two boys aged 7 and 10 years with probable primary ectopic (extradural) orbital meningiomas. Both patients presented with a gradual onset of progressive, painless proptosis. In addition, computed tomographic scans demonstrated involvement of the superomedial orbit without bony erosion or hyperostosis, but with expansion of the adjacent sinus. Neither tumor demonstrated attachment to the optic nerve or intracranial extension at the time of surgery. Both patients were successfully treated with complete surgical excision. Evaluation did not reveal the presence of neurofibromatosis in either child.

Conservative or surgical management of distal femoral fractures. A retrospective study with a minimum five year follow-up.

We report the outcome of conservative and surgical management in 50 skeletally mature patients (average age 64.6 years, 36 females patients) with 51 supracondylar femoral fractures treated in our unit between June 1991 and December 1993. Thirty-six fractures were caused by low-energy trauma, and 15 were due to high-energy trauma. Open fractures occurred in 5 patients. Of the 34 patients (35 fractures) treated conservatively, 15 (46%) achieved a satisfactory result. Of the 16 patients treated by internal fixation, 10 (62%) reached a satisfactory outcome. Osteoporosis, severe comminution of the fracture, involvement of the knee joint, and soft tissue injury in open fractures were associated with unsatisfactory results. Conservative management of these fractures is associated with a lesser chance of achieving a good functional result. With the advent of new fixation devices and our experience that conservative management can actually lead to many complications, the proportion of patients operated upon is likely to increase.

The semilunar flap technique for root coverage.

The semilunar flap technique may be considered as a simple, minimally invasive option for coronally repositioning the receded free gingival margin on the facial aspects of natural teeth and implants. Judicious case selection and careful application of the described procedure may enhance the final esthetic outcome using this approach. Work is currently in progress by the authors to provide long-term evidence-based results using this technique, with future considerations including the application of recent advances in microsurgical instrumentation to facilitate surgical tissue management.

Anti-tumour effects of Egyptian propolis on Ehrlich ascites carcinoma.

A total of 150 female Swiss mice were used to study the ability of water soluble propolis derivatives (WSPD) of Egyptian propolis to inhibit the proliferation and growth of Ehrlich ascites carcinoma (EAC) cells in mice. The mice were divided equally into three groups: the first was kept as a negative control group, the second received an intraperitoneal injection of 2.5 × 10(6) EAC and was kept as a positive control group and the third an intraperitoneal injection of 2.5 × 10(6) EAC and treated with propolis (50 mg/kg body weight) administered by gastric intubations 2 h prior to the intraperitoneal injection of EAC. The propolis was administered daily for 11 successive days. An examination of EAC cells revealed a reduction in the volume, total cell count, viable percentage and increase in the percentage of dead cells in the treated group with an increasing mean survival time (MST), increasing life span (ILS) percentage and treated vs positive control (T/C) percentage. Immunological studies revealed a significant increase in the lymphocyte transformation rate (LTR), phagocytic activity and killing power in the group treated with propolis. A haematological study of the parameters revealed leucocytosis in cancer-bearing mice and propolis-treated groups with granulocytosis and monocytosis. The erythrogram revealed a significant reduction in red blood cell (RBC) count in group 2. The result showed that the implantation of EAC in Swiss mice without treatment resulted in a significant decrease in total protein and albumin levels without a change in globulin level and a significant increase in creatinine level, while the third group that received propolis showed an improvement in these biochemical parameters compared to the normal control group.