High-Brightness High-Energy Electron Beams from a Laser Wakefield Accelerator via Energy Chirp Control

By designing a structured gas density profile between the dual-stage gas jets to manipulate electron seeding and energy chirp reversal for compressing the energy spread, we have experimentally produced high-brightness high-energy electron beams from a cascaded laser wakefield accelerator with peak energies in the range of 200-600 MeV, 0.4%-1.2% rms energy spread, 10-80 pC charge, and ∼0.2  mrad rms divergence. The maximum six-dimensional brightness B_{6D,n} is estimated as ∼6.5×10^{15}  A/m^{2}/0.1%, which is very close to the typical brightness of e beams from state-of-the-art linac drivers. These high-brightness high-energy e beams may lead to the realization of compact monoenergetic gamma-ray and intense coherent x-ray radiation sources.

A comprehensive, prospective study of penile dimensions in Chinese men of multiple ethnicities

This study aimed to establish a reference range of penile length and circumference of adult males in China, and to compare the penile dimensions of different ethnical backgrounds. To do this, penile length and circumference measurements were obtained from 5196 healthy males attending the Urology Counseling Clinic. The mean value of penile dimensions was a flaccid length of 6.5 ± 0.7 cm, a stretched length of 12.9 ± 1.2 cm and a flaccid circumference of 8.0 ± 0.8 cm. In the subgroup of 311 males, the mean erectile length was 12.9 ± 1.3 cm and the mean erectile circumference was 10.5 ± 0.9 cm, the mean flaccid and erectile glans lengths were 2.7 ± 0.3 and 3.4 ± 0.4 cm, respectively, and the mean flaccid and erectile glans diameters were 2.6 ± 0.2 and 3.4 ± 0.4 cm, respectively. We found that flaccid penile length and circumference varied among different ethnicities. This study established a reference range for penile dimensions, which will help when counseling patients worried about their penile size or seeking penis enlargement surgery. We also found that penile dimensions are different in different ethnicities, but further investigations are needed to validate this.

All-optical cascaded laser wakefield accelerator using ionization-induced injection

We report on near-GeV electron beam generation from an all-optical cascaded laser wakefield accelerator (LWFA). Electron injection and acceleration are successfully separated and controlled in different LWFA stages by employing two gas cells filled with a He/O2 mixture and pure He gas, respectively. Electrons with a Maxwellian spectrum, generated from the first LWFA assisted by ionization-induced injection, were seeded into the second LWFA with a 3-mm-thick gas cell and accelerated to be a 0.8-GeV quasimonoenergetic electron beam, corresponding to an acceleration gradient of 187  GV/m. The demonstrated scheme paves the way towards the multi-GeV laser accelerators.

Heparin-functionalized collagen matrices with controlled release of basic fibroblast growth factor

Tissue engineering scaffolds with controlled long-term release of growth factors are constructed in an attempt to mimic the intelligent ability of the extracellular matrix (ECM) to release endogenous growth factors. In this study, collagen sponges (Collagen group) were modified by N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) crosslinking (EDC/NHS group) and heparin immobilization (EDC/NHS-H group), and subsequently seeded with human umbilical vein endothelial cells (HUVECs). Native and modified sponges were pre-adsorbed with basic fibroblast growth factor (bFGF) to evaluate the sustained release and bioactive maintenance of bFGF from the sponges. We found that modified collagen matrices permitted HUVECs to proliferate and migrate well and to distribute uniformly. The EDC/NHS-H group exhibited an excellent sustained-release profile and bioactive maintenance of the pre-adsorbed bFGF as compared with the Collagen and EDC/NHS groups. These results suggest that heparin-functionalized collagen matrices can support a controlled release of bFGF and thus, have potential as a tissue engineering scaffold.

Transverse evolution of a plasma channel in air induced by a femtosecond laser

We investigate the evolution of filamentation in air by using a longitudinal diffraction method and a plasma fluorescence imaging technique. The diameter of a single filament in which the intensity is clamped increases as the energy of the pump light pulse increases, until multiple filaments appear.

Optical breakdown for silica and silicon with double femtosecond laser pulses

The optical breakdown thresholds (OBTs) of typical dielectric and semiconductor materials are measured using double 40-fs laser pulses. By measuring the OBTs with different laser energy and different time delays between the two pulses, we found that the total energy of breakdown decrease for silica and increase for silicon with the increase of the first pulse energy.

Phase dependence of relativistic electron dynamics and emission spectra in the superposition of an ultraintense laser field and a strong uniform magnetic field

The phase dependence of the dynamics and emission spectra of a fully relativistic electron in the superposition of an ultraintense plane wave laser field and a strong uniform magnetic field has been investigated. It is found that the effect of changing the initial laser phase is quite different for circularly and linearly polarized laser fields. For circular polarization only the axis of the helical trajectory is changed with variation of the initial laser field phase. However, for linear polarization, the effect of changing the initial phase is opposite in the two parameter regions divided by the resonance condition r=1 (r stands for the ratio between the reduced cyclotron frequency and laser frequency). When r<1, with increase in the initial laser field phase eta(0) from 0 to pi/2, both the radius of the electron's helical trajectory and the height of the peak related to the uniform magnetic field are decreased, and these two physical values are increased with an increase in the laser initial phase when r>1. The phase dependence of the electron's energy and velocity components was also studied. Some beat structure is found when eta(0)=0 and this structure is absent when eta(0)=pi/2.

Electron acceleration and high-order harmonic generation by an intense short pulse laser in a magnetic field

Electron acceleration and short-wavelength radiation generation by an intense, short, linearly polarized laser pulse in an external magnetic field parallel to that of the light wave is investigated classically. It is found that enhanced electron acceleration by the laser can occur. After the pulse has passed, much of the energy gained by the electron is retained in its relativistic cyclotron motion. The electron emits radiation at high harmonics of the cyclotron frequency until the static magnetic field decays.

Phylogeny and ontogeny of the lymphatic stomata connecting the pleural and peritoneal cavities with the lymphatic system--a review

This paper reviews the phylogeny and ontogeny of "lymphatic stomata" through which fluids and cells in the pleural and peritoneal cavities enter the lymphatic system. In amphibians, the pleuroperitoneal cavity is connected through numerous pores with the wide subvertebral lymphatic sinus corresponding to the thoracic duct in mammals. In reptiles, direct connections of the pleural and peritoneal cavities with the lymphatic system have been reported. In mammals, the pleural and peritoneal cavities are directly connected with lymphatics through lymphatic stomata. How do lymphatic stomata develop in mammals? In the rat, distinct lymphatics are noted in the subpleural space of the diaphragm periphery in 16 days old embryo. With age, the supleural lymphatics increase and form a polygonal network. They show a tubular appearance and possess many valves. Some of them become endowed with smooth muscle cells. In 19 days old embryos, some lymphatics appear in the subperitoneal space of the diaphragm. They extend centripetally and form many lateral projections that later elongate and connect with those from adjacent lymphatics, thus forming a lattice-like network or "lymphatic lacunae". During early postnatal days, the lymphatic lacunae project many bulges that subsequently come into contact with the pores among mesothelial cells lining the diaphragmatic peritoneum, thus forming lymphatic stomata. They increase until postnatal week 10. The lymphatic stomata in the costal pleura also develop during early postnatal days.

Structural studies of initial lymphatics adjacent to gastric and colonic malignant neoplasms

Invasion and metastases are the main causes of death from cancer, and prognosis is best correlated with invasion of malignant cells into initial lymphatics and dissemination to regional lymph nodes. Using both light and transmission electron microscopy, we examined human gastric and colonic cancers and their relation to initial lymphatics. Invasion of malignant tumor cells into the initial lymphatics was characterized by interdigitating and overlapping endothelium giving way to open junctions as lymphatic endothelial cells were apparently dissolved and destroyed. Cytoplasmic vesicles, mitochondria, and rough endoplasmic reticulum were qualitatively increased as demonstrated by image analysis.

[A clinical analysis of intramuscular hemangioma in oral and maxillofacial regions: Report of 59 cases]

From 1978 to 1992,the clinical data of 59 patients with intramuscular hemangioma in oral and maxillofacial regions were reviewed and analysed.The average age and the duration were 23 years old and eight years respectively.All patients were treated surgically,53 cases (89.83%)were completely resected and those of other 6 cases(10.1%) partially resected without any complications,Follow-up for 11 months to 12 years showed that 2 cases relapsed,and thus the cure rate was 96.6%(57/59),The author affirmed the significance of surgical operation in treatment and put forward the view of classification of hemangioma the vascular deformities.

[The effect of dosage on oral fluorescein angiography of the fundus]

105 patients were orally given fluorescein of different dosage and concentration for fundus angiography. The results indicated that the dosage of 30mg/kg at 2% concentration produced more distinct angiograms.

Shedding of human neuroblastoma gangliosides

Gangliosides shed by tumor cells are implicated in modulating tumor formation. For example, rapid progression of human neuroblastoma tumors is associated with high circulating levels of shed GD2 ganglioside. To elucidate the kinetic and qualitative characteristics of tumor cell ganglioside shedding, which is difficult to accomplish in vivo, we examined this process in LAN-5 human neuroblastoma cells in vitro. Three major gangliosides, GD2, GM2 and GT1b, comprise 82% of the mean total of 38 nmol LBSA/10(8) cells. These molecules are shed very rapidly (1-3 pmol/10(6) cells per h, or approx. 0.5% of the total cell gangliosides per h). Quantitative and qualitative characteristics of ganglioside shedding are remarkably constant over a 40-fold range of cell density. Not only GD2, but every major carbohydrate species is shed, in proportion to its concentration in the cell, with slightly greater shedding of ceramide subspecies containing shorter chain fatty acids. These findings were confirmed in three other neuroblastoma cell lines, LAN-1, IMR and KCNR. We suggest that the high expression and rapid generalized shedding of human neuroblastoma tumor gangliosides results in significant in vivo accumulation of these biologically active molecules during tumor growth.

[Antigen signature analysis of dengue-2 viruses strains in Hainan China]

In this paper, we try to define the extent of antigenic variation between dengue-2 viruses from Hainan province, which had been isolated over a period of 3 years (1985-1987). The dengue-2 viruses were compared with the prototype New Guinea B strain and were subjected to antigen signature analysis. Eight strains of dengue-2 virus were analyzed by three monoclonal antibodies: flavivirus group, subcomplex dengue-2 type-specific reactive epitopes, over a range of antigen concentration. Five out of eight dengue-2 virus strains showed them to be antigenically homogeneous, and the remaining three strains showed them to be heterogeneous. Signature analysis provides a rapid and simple means to different strains derived from different sources, thus permit monitoring changes or introductions of hew dengue virus populations in certain geographic region.

Compositional analysis of the three main gangliosides from adult human myometrium by a rapid capillary gas chromatographic method

A new capillary GC method is described for the compositional analysis of the three main gangliosides isolated from adult human myometrium. The sample was subjected to methanolysis, acetylation and trimethylsilylation which allows all the constituents to be analyzed simultaneously. The predominant ganglioside was found to be GD3, with GM3 and GT1b the next most abundant.