Super-strong magnetic field-dominated ion beam dynamics in focusing plasma devices.

High energy density physics is the field of physics dedicated to the study of matter and plasmas in extreme conditions of temperature, densities and pressures. It encompasses multiple disciplines such as material science, planetary science, laboratory and astrophysical plasma science. For the latter, high energy density states can be accompanied by extreme radiation environments and super-strong magnetic fields. The creation of high energy density states in the laboratory consists in concentrating/depositing large amounts of energy in a reduced mass, typically solid material sample or dense plasma, over a time shorter than the typical timescales of heat conduction and hydrodynamic expansion. Laser-generated, high current-density ion beams constitute an important tool for the creation of high energy density states in the laboratory. Focusing plasma devices, such as cone-targets are necessary in order to focus and direct these intense beams towards the heating sample or dense plasma, while protecting the proton generation foil from the harsh environments typical of an integrated high-power laser experiment. A full understanding of the ion beam dynamics in focusing devices is therefore necessary in order to properly design and interpret the numerous experiments in the field. In this work, we report a detailed investigation of large-scale, kilojoule-class laser-generated ion beam dynamics in focusing devices and we demonstrate that high-brilliance ion beams compress magnetic fields to amplitudes exceeding tens of kilo-Tesla, which in turn play a dominant role in the focusing process, resulting either in a worsening or enhancement of focusing capabilities depending on the target geometry.

Enhancing laser beam performance by interfering intense laser beamlets.

Increasing the laser energy absorption into energetic particle beams represents a longstanding quest in intense laser-plasma physics. During the interaction with matter, part of the laser energy is converted into relativistic electron beams, which are the origin of secondary sources of energetic ions, γ-rays and neutrons. Here we experimentally demonstrate that using multiple coherent laser beamlets spatially and temporally overlapped, thus producing an interference pattern in the laser focus, significantly improves the laser energy conversion efficiency into hot electrons, compared to one beam with the same energy and nominal intensity as the four beamlets combined. Two-dimensional particle-in-cell simulations support the experimental results, suggesting that beamlet interference pattern induces a periodical shaping of the critical density, ultimately playing a key-role in enhancing the laser-to-electron energy conversion efficiency. This method is rather insensitive to laser pulse contrast and duration, making this approach robust and suitable to many existing facilities.

Boosting laser-ion acceleration with multi-picosecond pulses.

Using one of the world most powerful laser facility, we demonstrate for the first time that high-contrast multi-picosecond pulses are advantageous for proton acceleration. By extending the pulse duration from 1.5 to 6 ps with fixed laser intensity of 1018 W cm-2, the maximum proton energy is improved more than twice (from 13 to 33 MeV). At the same time, laser-energy conversion efficiency into the MeV protons is enhanced with an order of magnitude, achieving 5% for protons above 6 MeV with the 6 ps pulse duration. The proton energies observed are discussed using a plasma expansion model newly developed that takes the electron temperature evolution beyond the ponderomotive energy in the over picoseconds interaction into account. The present results are quite encouraging for realizing ion-driven fast ignition and novel ion beamlines.

Isoflavone supplements stimulated the production of serum equol and decreased the serum dihydrotestosterone levels in healthy male volunteers.

The aim of this study was to evaluate the effect of supplementing healthy men with soy isoflavones on the serum levels of sex hormones implicated in prostate cancer development. A total of 28 Japanese healthy volunteers (18 equol producers and 10 equol non-producers) between 30 and 59 years of age were given soy isoflavones (60 mg daily) supplements for 3 months, and the changes in their sex hormone levels were investigated at the baseline and after administration. The serum and urine concentrations of daidzein, genistein, and the levels of equol in the fasting blood samples and 24-h stored urine samples were also measured. All 28 volunteers completed the 3-month supplementation with isoflavone. No changes in the serum levels of estradiol and total testosterone were detected after 3-month supplementation. The serum levels of sex hormone-binding globulin significantly increased, and the serum levels of free testosterone and dihydrotestosterone (DHT) decreased significantly after 3-month supplementation. Among the 10 equol non-producers, equol became detectable in the serum of two healthy volunteers after 3-month supplementation. This study revealed that short-term administration of soy isoflavones stimulated the production of serum equol and decreased the serum DHT level in Japanese healthy volunteers. These results suggest the possibility of converting equol non-producers to producers by prolonged and consistent soy isoflavones consumption.

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP.

Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men.

Racial differences in the incidence of prostate cancer are manifest worldwide, possibly due to the different dietary habits. To elucidate the relationship between the recent trend of phytoestrogenic isoflavone intake and the increased incidence of prostate cancer in Japan, we conducted an age-stratified dietary survey of soybean foods in 102 Japanese healthy men (age range: 10-59 years) and measured the serum isoflavones and equol levels in them and 100 Korean healthy men. The intergroup comparison among the age-stratified groups showed significant differences in the daily intake of genistein and daidzein between the teenager group and the other groups of age >or=30 years (P<0.05). In the Japanese study, the proportion of equol producers in the teenager group was 10%, being significantly the lowest among the age-stratified groups. The proportions of equol producers in the age-stratified groups from 10 to 49 years were also significantly lower than those in the fifties. The equol non-producers consumed significantly less amounts of isoflavones than the equol producers. In the Korean study, the proportions of equol producers were 45% in the teenager and 40% in the twenties and thirties, being significantly lower than in the forties (80%) and fifties (65%). The decreased intake of isoflavones, low serum level of equol and low incidence of equol production in the young generation may become potential risk factors for prostate cancer not only in Japan but also in Korea in the near future. Elucidating the mechanism of equol production may be promising in developing strategies for chemoprevention against prostate cancer.

Comprehensive diagnosis of growth rates of the ablative Rayleigh-Taylor instability.

The growth rate of the ablative Rayleigh-Taylor instability is approximated by gamma = square root[kg/(1 + kL)] - beta km/rho(a), where k is the perturbation wave number, g the gravity, L the density scale length, m the mass ablation rate, and rho(a) the peak target density. The coefficient beta was evaluated for the first time by measuring all quantities of this formula except for L, which was taken from the simulation. Although the experimental value of beta = 1.2+/-0.7 at short perturbation wavelengths is in reasonably good agreement with the theoretical prediction of beta = 1.7, it is found to be larger than the prediction at long wavelengths.

Electron bunch trapping and compression by an intense focused pulse laser.

A focused short-pulse laser of TEM (1,0)+TEM (0,1) mode has two intensity peaks in the radial direction, so that the transverse ponderomotive force may trap electrons between the two peaks. At the same time the longitudinal ponderomotive force may accelerate electrons at the head of the laser pulse, when the laser is focused. When the electrons move to the laser tail, the laser may diverge and the electron deceleration becomes relatively weak. Our numerical analyses demonstrate that electrons are trapped well by the laser potential well, and that at the same time the acceleration by the longitudinal ponderomotive force induces the electron bunch compression. This trapping and compression mechanism is unique: the electron bunch can be compressed to the scale of the laser pulse length.

Multisegmented kinoform phase plate for spatial and temporal control of the focal-plane irradiance profile.

Kinoform phase plates (KPPs) are widely used in inertial confinement fusion to improve energy efficiency and to produce an optimum irradiance profile on the target plane. However KPPs are sensitive to beam aberrations and offer little flexibility in temporally tailoring the far-field pattern. To overcome these problems, we developed a multisegmented KPP and demonstrated temporal control of a focusing pattern and protection against phase distortions by numerical simulations.

Laguerre-Gaussian beam generated with a multilevel spiral phase plate for high intensity laser pulses.

We investigated an Laguerre-Gaussian (LG) beam that can carry an orbital angular momentum and has a doughnut-shaped intensity pattern. We developed a multilevel spiral phase plate (SPP) that generates an LG beam by applying the wave surface of a spiral structure directly to a Gaussian beam for application to microscopic laser material processing.We experimentally demonstrate, for the first time, that it is possible to generate an LG beam with the multilevel SPP that allows the use in high intensity laser pulses.

Spectroscopic determination of dynamic plasma gradients in implosion cores.

The time-dependent gradient structure of a laser-compressed, high-energy-density plasma has been determined using a method based on the simultaneous analysis of time-resolved x-ray monochromatic images and x-ray line spectra from Ar-doped D2 implosion cores. The analysis self-consistently determines the temperature and density gradients that yield the best fits to the spatial-emissivity profiles and spectral line shapes. This measurement is important for understanding the spectra formation and plasma dynamics associated with the implosion process. In addition, since the results are independent of hydrodynamic simulations, they are also important for comparison with fluid-dynamic models.

Three-directional spectral dispersion for smoothing of a laser irradiance profile.

In inertial confinement fusion research, uniform laser irradiation on a fusion target is a key issue. We propose a new method of beam smoothing in which we use three-directional spectral dispersion to reduce the coherent speckle that is unavoidable in the usual two-directional spectral-dispersion scheme. We have used this smoothing technique in a Nd:glass laser system and have demonstrated that the coherent speckle is reduced by a factor of 2.9 from that in two-directional spectral dispersion.

[Verify the optimum administration of anticancer agent--cisplatin].

Cisplatin shows effectiveness for various solid cancers and often plays a role as the key drug in combination chemotherapy. The most common method of cisplatin administration is bolus intra-venous injection. However, other administration methods are tried in order to reinforce the effect, and also to reduce the side effects. Generally, renal damage is more prominent with bolus injection. In contrast, bone marrow suppression is more severe with intermittent administration. Although there is no clear evidence about the anti-tumor effects, a dramatic local effect is sometimes observed by intra-arterial chemotherapy. By intraperitoneal chemotherapy, while a systemic effect is observed in addition to local effects, due consideration of the systemic side effects is also needed. These protocols are used in many institutes, but the efficacy is not yet proven by comparison trials. In future, randomized prospective studies should be performed to test the usefulness of the regimens.

Fast heating of ultrahigh-density plasma as a step towards laser fusion ignition.

Modern high-power lasers can generate extreme states of matter that are relevant to astrophysics, equation-of-state studies and fusion energy research. Laser-driven implosions of spherical polymer shells have, for example, achieved an increase in density of 1,000 times relative to the solid state. These densities are large enough to enable controlled fusion, but to achieve energy gain a small volume of compressed fuel (known as the 'spark') must be heated to temperatures of about 108 K (corresponding to thermal energies in excess of 10 keV). In the conventional approach to controlled fusion, the spark is both produced and heated by accurately timed shock waves, but this process requires both precise implosion symmetry and a very large drive energy. In principle, these requirements can be significantly relaxed by performing the compression and fast heating separately; however, this 'fast ignitor' approach also suffers drawbacks, such as propagation losses and deflection of the ultra-intense laser pulse by the plasma surrounding the compressed fuel. Here we employ a new compression geometry that eliminates these problems; we combine production of compressed matter in a laser-driven implosion with picosecond-fast heating by a laser pulse timed to coincide with the peak compression. Our approach therefore permits efficient compression and heating to be carried out simultaneously, providing a route to efficient fusion energy production.

[Intrascrotal tumors: a clinicopathologic study of 15 cases].

PURPOSE: We reviewed cases of intrascrotal tumors treated at our institution except for germ cell testicular tumors. PATIENTS AND METHODS: From 1977 to 1998 (22 years), 120 cases of intrascrotal tumors treated at the University of Tsukuba. Of these, 15 cases (12.5%) were not germ cell testicular tumors. The patients' ages varied between 2 and 77 years with a mean of 49.6. RESULTS: The most common complaint regarding symptoms was painless testicular enlargement. Tumor weight ranged from 2 to 200 g, with an average of 104.6 g. The histological diagnoses of 15 patients were 8 malignant lymphomas, 2 paratesticular rhabdomyosarcomas, 2 metastatic tumors (origin; stomach and prostate), 1 epidermoid cyst, 1 cyst of tunica testis, and 1 adenomatoid tumor. As for the cases with malignant lymphoma, all of them were non-Hodgkin's lymphoma whose clinical stages were stage I in 2 cases and stage IV in 6 cases. Five 8 patients died in spite of systemic chemotherapy after an orchiectomy, whereas 2 cases with metastatic tumors died of primary cancer, and two cases with paratesticular rhabdomyosarcoma are still alive and have had no evidence of disease. CONCLUSIONS: Intrascrotal tumors except for germ cell testicular tumors are not common, and consist of various diseases. In particular, some kinds of malignant lymphoma mimic anaplastic seminoma histopathologically. Therefore, accurate diagnosis and precise treatment is important in the patient with intrascrotal tumors.

High-dose chemotherapy with peripheral blood stem cell transplantation for advanced testicular cancer.

BACKGROUND: The present study was performed in order to investigate the efficacy and safety of high-dose chemotherapy for the treatment of patients with advanced testicular cancer. METHODS: Seven patients were treated with high-dose carboplatin, etoposide and cyclophosphamide followed by peripheral blood stem cell transplantation. Five patients received one cycle and two patients received two cycles of the high-dose chemotherapy. RESULTS: Of the seven patients, one achieved a complete response and four achieved partial responses with markers negative. As a result of subsequent surgery for residual tumors, three of the four partial responders showed no residual cancer cells. One patient who did not undergo surgery received radiotherapy after the high-dose chemotherapy and the residual tumors disappeared. All five patients who had either a complete or partial response are still alive and without evidence of disease at 12, 27, 30, 37 and 40 months. One patient is alive with disease at 7 months and one died of progressive disease at 6 months. The hematologic recovery after high-dose chemotherapy was rapid and non-hematologic toxicities were usually mild and manageable. CONCLUSIONS: High-dose chemotherapy followed by peripheral blood stem cell transplantation is safe and effective for use in patients with far-advanced testicular cancer, particularly when the high-dose chemotherapy is conducted as the initial treatment. Further larger and long-term follow-up studies are needed to define the role of high-dose chemotherapy on testicular cancer.

[Evidence-based medicine for urological cancer chemotherapy].

We reviewed the treatment results of urological cancer chemotherapy from the standpoint of evidence based medicine. In the treatment of advanced transitional cell carcinoma of the urothelium, M-VAC (MTX + VBL + ADM + CDDP) is regarded as the standard regimen; however, durable event-free survival is rare. There is no level 1 evidence to date showing that the use of neoadjuvant or adjuvant cisplatin-based regimens will improve survival in cases of locally advanced bladder cancer. Immunotherapy with interferon or interleukin-2 produces a small survival advantage in patients with metastatic renal cell carcinoma. There is no evidence that adjuvant interferon-alpha administration will improve the survival in those with non-metastatic renal cell carcinoma. Systematized cisplatin-based treatment protocols have been established in patients with advanced testicular germ cell tumor by means of many randomized controlled trials. Several clinical trials are under way to prove the efficacy of high dose chemotherapy (with autologous stem-cell support) in patients with poor risk germ cell tumors. We do not yet have sufficient data to conclude whether maximal androgen blockade will prolong the survival in patients with metastatic prostate cancer, nor to conclude whether neoadjuvant androgen depletion treatment improve disease free survival of the patients after radical prostatectomy.

A bladder preservation regimen using intra-arterial chemotherapy and radiotherapy for invasive bladder cancer: a prospective study.

BACKGROUND: A prospective study was performed to investigate combined treatment with intra-arterial chemotherapy and radiation therapy for bladder preservation in locally invasive bladder cancer. METHODS: Patients with invasive bladder cancer, stage T2-3N0M0, were included in the study. Intra-arterial chemotherapy was performed with three injections of methotrexate and cisplatin at 3-week intervals. Simultaneously, the patients underwent X-ray irradiation (40 Gy) of the small pelvic space. Where a post-treatment transurethral resection (TUR) biopsy showed no residual tumor, the tumor site was irradiated by a 30 Gy proton beam and the bladder was preserved. Where tumors remained, radical cystectomy was performed. RESULTS: Between 1990 and 1996, 42 patients were treated according to this protocol. Post-treatment TUR biopsy and urine cytology showed no residual tumors in 39 of 42 cases (93%). The bladder was preserved in accordance with the study protocol in 36 cases. A median follow-up of 38 months showed 3-year non-recurrence in 72% of bladder-preserved patients and the rate of bladder preservation was 84%. The nine recurrences included eight cases of superficial bladder recurrence. One cancer death occurred among the bladder-preservation patients, giving 3-year survival and cause-specific survival rates of 84% and 100%, respectively. Although bladder function decreased slightly in compliance, bladder capacity was retained in almost all cases. CONCLUSIONS: This regimen is useful for bladder preservation in T2-3 locally invasive bladder cancer. Information from more cases and the results of more long-term observations are needed, as is an evaluation of appropriate subject selection and factors associated with quality of life issues, particularly regarding bladder function.

[Cases of refractory testicular cancer treated with all trans-retinoic acid].

We reported two cases of chemotherapy-refractory testicular cancer treated with all trans-retinoic acid (ATRA). Case 1. A 21-year-old male patient underwent salvage surgery for lung metastasis which had developed after treatment with three different cisplatin-based chemotherapy regimens for malignant teratoma. After recovery from surgery, he was treated with oral ATRA at daily dose 80 mg/m2 for four weeks. Case 2. A-45-year-old patient suffered from lung metastasis after orchiectomy for teratocarcinoma. The patient failed to achieve a complete response despite two different cisplatin-based chemotherapy and high dose chemotherapy regimens with bone marrow rescue. He was treated with oral ATRA for five weeks. Both patients showed disease progression with increase in tumor size and elevation of tumor marker during ATRA therapy. Side effects were acceptable except the headache in Case 2, who needed a dose reduction of ATRA. In conclusion, oral ATRA with this dose failed to show clinical antitumor activity in patients with refractory testicular cancer.