Laser plasmas can be produced when high-power laser beams are focused in matter. A focused laser beam of TW(terawatt)-level high power has an extremely strong electric field, so neutral atoms are ...immediately ionized by the laser electric field, leading to a laser-produced plasma. The laser plasma can be produced by small table-top TW lasers based on the CPA (chirped-pulse amplification) technique, and now they are rather easily available even in university laboratories. In Korea, there are several CPA-based TW (or even petawatt) lasers in a few institutions, and they have been used for diverse laser plasma physics research and applications, including the laser acceleration for electrons and ions, high-power THz (tera-hertz) generation, advanced light sources, high-energy-density plasmas, plasma optics, etc. This paper reviews some of the laser plasma physics research and applications that have been performed in several universities and research institutes.
Aims/hypothesis
Human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hIPSCs) offer unique opportunities for regenerative medicine and for the study of mammalian development. ...However, developing methods to differentiate hESCs/hIPSCs into specific cell types following a natural pathway of development remains a major challenge.
Methods
We used defined culture media to identify signalling pathways controlling the differentiation of hESCs/hIPSCs into pancreatic or hepatic progenitors. This approach avoids the use of feeders, stroma cells or serum, all of which can interfere with experimental outcomes and could preclude future clinical applications.
Results
This study reveals, for the first time, that activin/TGF-β signalling blocks pancreatic specification induced by retinoic acid while promoting hepatic specification in combination with bone morphogenetic protein and fibroblast growth factor. Using this knowledge, we developed culture systems to differentiate human pluripotent stem cells into near homogenous population of pancreatic and hepatic progenitors displaying functional characteristics specific to their natural counterparts. Finally, functional experiments showed that activin/TGF-β signalling achieves this essential function by controlling the levels of transcription factors necessary for liver and pancreatic development, such as HEX and HLXB9.
Conclusion/interpretation
Our methods of differentiation provide an advantageous system to model early human endoderm development in vitro, and also represent an important step towards the generation of pancreatic and hepatic cells for clinical applications.
We report the results of an 87 deg{sup 2} point-source survey centered at R.A. 5{sup h}30{sup m}, decl. -55{sup 0} taken with the South Pole Telescope at 1.4 and 2.0 mm wavelengths with arcminute ...resolution and milli-Jansky depth. Based on the ratio of flux in the two bands, we separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei and the other consistent with thermal emission from dust. We present source counts for each population from 11 to 640 mJy at 1.4 mm and from 4.4 to 800 mJy at 2.0 mm. The 2.0 mm counts are dominated by synchrotron-dominated sources across our reported flux range; the 1.4 mm counts are dominated by synchrotron-dominated sources above {approx}15 mJy and by dust-dominated sources below that flux level. We detect 141 synchrotron-dominated sources and 47 dust-dominated sources at signal-to-noise ratio S/N >4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs. Some of the dust-dominated sources are associated with nearby (z << 1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite. However, most of the bright, dust-dominated sources have no counterparts in any existing catalogs. We argue that these sources represent the rarest and brightest members of the population commonly referred to as submillimeter galaxies (SMGs). Because these sources are selected at longer wavelengths than in typical SMG surveys, they are expected to have a higher mean redshift distribution and may provide a new window on galaxy formation in the early universe.
The recent advancement of high-intensity lasers has made all-optical Compton scattering become a promising way to produce ultrashort brilliant γ-rays in an ultra-compact system. However, so far ...achieved Compton γ-ray sources are limited by low conversion efficiency and spectral intensity. Here we present a highly efficient gamma photon emitter obtained by irradiating a high-intensity laser pulse on a miniature plasma device consisting of a plasma lens and a plasma mirror. This concept exploits strong spatiotemporal laser-shaping process and high-charge electron acceleration process in the plasma lens, as well as an efficient nonlinear Compton scattering process enabled by the plasma mirror. Our full three-dimensional particle-in-cell simulations demonstrate that in this novel scheme, brilliant γ-rays with very high conversion efficiency (higher than 10−2) and spectral intensity (∼109 photons 0.1 % BW ) can be achieved by employing currently available petawatt-class lasers with intensity of 1021 W cm−2. Such efficient and intense γ-ray sources would find applications in wide-ranging areas.
We report on the status of an ongoing effort to develop arrays of horn-coupled, polarization-sensitive microwave kinetic inductance detectors (MKIDs) that are each sensitive to two spectral bands ...between 125 and 280 GHz. These multi-chroic MKID arrays are tailored for next-generation, large-detector-count experiments that are being designed to simultaneously characterize the polarization properties of both the cosmic microwave background and Galactic dust emission. We present our device design and describe laboratory-based measurement results from two 23-element prototype arrays. From dark measurements of our first engineering array, we demonstrated a multiplexing factor of 92, showed the resonators respond to bath temperature changes as expected, and found that the fabrication yield was 100%. From our first optically loaded array, we found the MKIDs respond to millimeter-wave pulses; additional optical characterization measurements are ongoing. We end by discussing our plans for scaling up this technology to kilo-pixel arrays over the next 2 years.
The demand for renewable energy is steadily increasing due to rapid population growth and economic development worldwide. An additional reason is that fossil fuel reserves are limited, and this ...situation results in their non-uniform availability globally. Furthermore, the attitudes of the society, energy policies and technology choices are constantly changing. Thus, renewable energy resources are now considered good alternatives to fossil fuels. In the meantime, liquid energy, such as methyl ester from locally produced vegetable oils, is well accepted by many countries, even though it is currently being blended up to 20% with petroleum fuels. Recently, the industrialisation of biodiesel is a major problem because of its poor cold flow properties and oxidative stability. Vegetable oils are also being blended in an appropriate proportion before transesterification to obtain the desired properties in biodiesel. Similarly, poor cold flow properties and oxidative stability can be improved by choosing suitable vegetable oils for making blends. Amongst all available vegetable oils, sesame seed oil (SSO) has unique cold flow properties and oxidation stability, particularly because of naturally occurring antioxidants and preservatives, which enhance the stability of oil towards rancidity. Therefore, SSO can be used as a potential feedstock for blending with other vegetable oils to enhance the overall cold flow and oxidation stability properties. This overview summarises sesame cultivation, SSO production, the physicochemical properties of SSO and its potential as an alternative renewable fuel source. In this review, the physicochemical properties of sesame biodiesel are compared with those of biodiesel derived from other vegetable oils. Results show that blending SSO with palm oil before transesterification will successfully improve the cold flow properties and oxidation stability of palm methyl ester (biodiesel).
The interaction of oblique monochromatic incident waves with horizontal/inclined/dual porous plates is investigated in the context of two-dimensional linear potential theory and Darcy's law (the ...normal velocity of fluid passing through a thin porous plate is linearly proportional to the pressure difference across it). The developed theory is verified by both small-scale and full-scale experiments. First, matched eigenfunction expansion (MEE) solutions for a horizontal porous plate are obtained. The relationship between the plate porosity and the porous parameter is obtained from systematic model tests by using six porous plates with different sizes and spacing of circular holes. Secondly, a multi-domain boundary-element method (BEM) using simple-sources (second-kind modified Bessel function) is developed to confirm the MEE solutions and to apply to more general cases including inclined or multiple porous plates. The BEM-based inner solutions are matched to the eigenfunction-based outer solutions to satisfy the outgoing radiation condition in the far field. Both analytical and BEM solutions with the developed empirical porous parameter agree with each other and correlate well with both small-scale data from a two-dimensional wave-tank test and full-scale measurement in a large wave basin. Using the developed predictive tools, wave-absorption efficiency is assessed for various combinations of porosity, water depth, submergence depth, wave heading, and plate/wave characteristics. In particular, it is found that the performance can be improved by imposing the proper inclination angle near the free surface. The optimal porosity is near porosity P=0.1 and the optimal inclination angle is around 10° as long as the plate length is greater than 20% of the wavelength. Based on the selected optimal parameters (porosity=0.1 and inclination angle=11.3°), the effective wave-absorption system for MOERI's square basin is designed.
A new mechanism for electromagnetic emission in the terahertz (THz) frequency regime from laser-plasma interactions is described. A localized and long-lasting transverse current is produced by two ...counter-propagating short laser pulses in weakly magnetized plasma. We show that the electromagnetic wave radiating from this current source, even though its frequency is close to cut-off of the ambient plasma, grows and diffuses towards the plasma-vacuum boundary, emitting a strong monochromatic THz wave. With driving laser pulses of moderate power, the THz wave has a field strength of tens of MV m−1, a frequency of a few THz and a quasi-continuous power that exceeds all previous monochromatic THz sources. The novelty of the mechanism lies in a diffusing electromagnetic wave close to cut-off, which is modelled by a continuously driven complex diffusion equation.
Aim Brain metastasis is infrequent in colorectal cancer patients, and the prognosis is poor. In this retrospective study survival and prognostic factors were determined in patients with brain ...metastasis from colorectal cancer.
Method Between 1997 and 2006, 39 patients with brain metastasis from colorectal cancer who survived more than 1 month were identified. Data were collected with regard to patient characteristics, location and stage of the primary tumour, extent and location of metastatic disease, and treatment modalities used.
Results Most (79.5%) patients had pulmonary metastases before brain metastasis, and the brain was the site of solitary metastasis in only one patient. The most frequent symptom was weakness 18 (43.6%) patients. Overall median survival was 5.0 months and the 1‐ and 2‐year survival rates were 21.8 and 9.1%, respectively. Univariate analysis revealed uncontrolled extracranial metastases (P = 0.019), multiple brain lesions (P = 0.026), bilateral brain metastases (P = 0.032) and serum carcinoembryonic antigen levels greater than 5 ng/ml (P = 0.008) to be poor prognostic factors. The median survival after the diagnosis of brain metastasis was significantly longer in patients who underwent surgical resection (15.2 ± 8.0 months) than in those treated by other modalities (P = 0.001). Treatment modality was the only independent prognostic factor for overall survival in patients with brain metastases from colorectal cancers (P = 0.015).
Conclusion Aggressive surgical resection in selected patients with brain metastases from colorectal cancer may prolong survival, even in the presence of extracranial metastatic lesions.
Background
Sentinel node navigation surgery reduces the extent of gastric and lymph node dissection, and may improve quality of life. The benefit and harm of laparoscopic sentinel node navigation ...surgery (LSNNS) for early gastric cancer is unknown. The SENORITA (SEntinel Node ORIented Tailored Approach) trial investigated the pathological and surgical outcomes of LSNNS compared with laparoscopic standard gastrectomy (LSG) with lymph node dissection.
Methods
The SENORITA trial was an investigator‐initiated, open‐label, parallel‐assigned, non‐inferiority, multicentre RCT conducted in Korea. The primary endpoint was 3‐year disease‐free survival. The secondary endpoints, morbidity and mortality within 30 days of surgery, are reported in the present study.
Results
A total of 580 patients were randomized to LSG (292) or LSNNS (288). Surgery was undertaken in 527 patients (LSG 269, LSNNS 258). LSNNS could be performed according to the protocol in 245 of 258 patients, and a sentinel node basin was detected in 237 (96·7 per cent) Stomach‐preserving surgery was carried out in 210 of 258 patients (81·4 per cent). Postoperative complications occurred in 51 patients in the LSG group (19·0 per cent) and 40 (15·5 per cent) in the LSNNS group (P = 0·294). Complications with a Clavien–Dindo grade of III or higher occurred in 16 (5·9 per cent) and 13 (5·0 per cent) patients in the LSG and LSNNS groups respectively (P = 0·647).
Conclusion
The rate and severity of complications following LSNNS for early gastric cancer are comparable to those after LSG with lymph node dissection. Registration number: NCT01804998 (
http://www.clinicaltrials.gov).
Antecedentes
La cirugía de navegación del ganglio centinela (sentinel node navigation surgery, SNNS) reduce la extensión de la resección gástrica y ganglionar, y puede mejorar la calidad de vida. Se desconoce el beneficio y el daño de la cirugía de navegación del ganglio centinela por vía laparoscópica (laparoscopic sentinel node navigation surgery, LSNNS) para el cáncer gástrico precoz. El ensayo clínico SENORITA investigó los resultados patológicos y quirúrgicos de LSNNS en comparación con la gastrectomía laparoscópica estándar (laparoscopic gastrectomy, LSG) con disección ganglionar (lymph node dissection, LND).
Métodos
El ensayo SENORITA fue un ensayo multicéntrico aleatorizado y controlado, iniciado por investigadores, abierto, con asignación a grupos paralelos y de no inferioridad llevado a cabo en Corea. El resultado primario fue la supervivencia libre de enfermedad a los 3 años. En el presente estudio, se describen los resultados secundarios correspondientes a morbilidad y mortalidad a los 30 días del postoperatorio.
Resultados
Un total de 580 pacientes fueron aleatorizados a LG (n = 292) o LSNNS (n = 288). La cirugía se realizó en 527 pacientes (LG 269, LSNNS 258). LSNNS pudo ser realizada de acuerdo con el protocolo en 245 de 258 pacientes y en 237 de 245 pacientes (96,7%) se detectó un ganglio centinela. La cirugía con preservación del estómago se realizó en 210 de 258 pacientes (81,4%). Las complicaciones postoperatorias se presentaron en 51 pacientes del grupo LSG (19,0%) y en 40 pacientes (15,5%) del grupo LSNNS (P = 0,294). Las complicaciones grado III o mayor de Clavien‐Dindo se detectaron en 16 (5,9%) y 13 pacientes (5,0%) de los grupos LSG y LSNNS, respectivamente (P = 0,647).
Conclusión
El porcentaje y la gravedad de las complicaciones tras LSNNS para cancer gástrico precoz son comparables a la LSG con LND.
The prospective, multicentre, randomized controlled phase III SENORITA trial evaluated the surgical and oncological outcomes of laparoscopic sentinel node navigation surgery (LSNNS) compared with laparoscopic standard gastrectomy (LSG) with lymph node dissection (LND) for early gastric cancer (EGC). LSNNS for EGC is a safe procedure in terms of postoperative morbidity and mortality compared with LSG and LND. ESD, endoscopic submucosal dissection; mITT, modified intention to treat; FAS, full analysis set; OGJ, oesophagogastric junction; LDG, laparoscopic distal gastrectomy; LTG, laparoscopic total gastrectomy; LPPG, laparoscopic pylorus‐preserving gastrectomy; LPG, laparoscopic proximal gastrectomy; ODG, open distal gastrectomy; OTG, open total gastrectomy; PP, per protocol; SBD, sentinel basin dissection; EFTR, endoscopic full‐thickness resection; LWR, laparoscopic wedge resection; LSR, laparoscopic segmental resection.
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