Comment on "Theory of tailoring sonic devices: Diffraction dominates over refraction"

Recently N. Garcia et al. (Phys. Rev. E 67, 046606 (2003)) theoretically studied several acoustic devices with dimensions on de order of several wavelenghts. The authors discussed on experimental results previously reported by several of us (F. Cervera et al., Phys. Rev. Lett. 88, 023902 (2002)). They concluded that diffraction and not refraction is the ominating mechanism that explain the focusing effects observed in those experiments. In this Comment we reexamined their calculations and discussed why some of their interpretations of our results are misleading.Comment: 2 pages, 2 figures, a comment on an articl

Collisional Penrose Process near the Horizon of Extreme Kerr Black Holes

Collisions of particles in black hole ergospheres may result in an arbitrarily large center-of-mass energy. This led recently to the suggestion [M. Banados, J. Silk, and S. M. West, Phys. Rev. Lett. 103, 111102 (2009)] that black holes can act as ultimate particle accelerators. If the energy of an outgoing particle is larger than the total energy of the infalling particles, the energy excess must come from the rotational energy of the black hole and hence, a Penrose process is involved. However, while the center-of-mass energy diverges, the position of the collision makes it impossible for energetic particles to escape to infinity. Following an earlier work on collisional Penrose processes [T. Piran and J. Shaham, Phys. Rev. D 16, 1615 (1977)], we show that even under the most favorable idealized conditions the maximal energy of an escaping particle is only a modest factor above the total initial energy of the colliding particles. This implies that one should not expect collisions around a black hole to act as spectacular cosmic accelerators

Vaccines : A rapidly evolving technology - Are the hurdles being addressed?

AbstractVaccination usually works in infectious disease, why not in Cancer? Differences in the potency of microbial and cancer antigens, poor initiation of an immune response due to inadequate expression of tumour associated antigens, weak antigens or tolerance induction and local immune suppression were considered. There is a big difference between a therapeutic and a prophylactic vaccine.The opinion of the expert group was that an improved therapeutic efficacy can hardly be expected by further variation of types of vaccines, schedules, routes of administration and adjuvants alone. A major hurdle for developing therapeutic cancer vaccines is the need to effectively monitor the immune response and to be able to use this in an adaptive trial approach.End-points of assessment should be different from standard treatments as complete response or partial responses are usually low, unless combined with other therapies.In order to focus resources to overcome the hurdles of enhancing the therapeutic efficacy of cancer vaccines the Cancer Vaccine Clinical Trial Working Group, representing academia and the pharmaceutical and biotechnology industries has in a consensus process defined 'A clinical development paradigm for cancer vaccines and related biologics'

Harvsådd i konventionella och plöjningsfria bearbetningssystem

I en serie med långliggande försök jämfördes två storruteled (plöjning till 25 cm djup respektive stubbearbetning till 13 cm djup) och två småruteled (konventionell såbäddsberedning och sådd respektive harv sådd) för att testa om en reducering av antalet överfarter minskar de negativa effekter av packning av centrala matjorden som förknippas med plöjningsfri odling. Skörden bestämdes varje år på alla platserna. En undersökning av jordens fysikaliska och kemiska egenskaper samt rotfördelning genomfördes 1991 på en av de fyra försöksplatserna. - Bearbetningsdjup, aggregatstorleksfördelning och vattenhalt i såbädden och i såbäddens botten var liknande i de olika leden medan såbäddens botten var jämnare i det oplöjda ledet. Det påverkade ej grödans uppkomst, som var liknande mellan leden. - Andelen porer > 100 µm, porkontinuitet, mättad vattengenomsläpplighet och luftgenomsläpplighet påverkades positivt av plöjningsfri odling jämfört med konventionell bearbetning. - Skrymdensitet, packningsgrad och penetrometermotstånd var liknande i bearbetningssystemen i nivån 0-13 cm, men signifikant högre i oplöjda led i nivån 13-25 cm, där rotdensiteten var signifikant lägre. - Kalium och kol var koncentrerade till de övre 13 cm i oplöjda rutor, medan fosfor och pH ej påverkades av bearbetningssystemen. - Harvsådd gav 2 % högre skörd än konventionell såbäddsberedning och verkar vara ett gott alternativ till konventionell såbäddsberedning, men andra metoder för att reducera packningen av jorden, som till exempel däck med extremt låga tryck, bör testas

Montana Kaimin, November 29, 1967

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/5498/thumbnail.jp

Fully engineered homoepitaxial zinc oxide nanopillar array for near-surface light wave manipulation

We report accurate light wave manipulation by means of an inverse designed homoepitaxial ZnO nanopillar array. Our proof-of-concept structure was optimized for focusing a near-surface light beam which propagates in a free-space parallel to the metal top surface. The on-purpose positioned and perpendicularly aligned vertical ZnO nanopillars were fabricated by homoepitaxial chemical growth technique. The obtained focal distance of 28 (mű)m as well as the light intensity distribution pattern was verified by three-dimensional finite-difference time-domain method. The demonstrated approach can provide inter- and intrachip optical connections in the next generation ZnO nanowire-based integrated photonic devices

Allelic loss at chromosome 13q12-q13 is associated with poor prognosis in familial and sporadic breast cancer.

Loss of heterozygosity (LOH) was analysed in 84 primary tumours from sporadic, familial and hereditary breast cancer using five microsatellite markers spanning the chromosomal region 13q12-q13 which harbours the BRCA2 breast cancer susceptibility gene, and using one other marker located within the RBI tumour-suppressor gene at 13q14. LOH at the BRCA2 region was found in 34% and at RBI in 27% of the tumours. Selective LOH at BRCA2 occurred in 7% of the tumours, whereas selective LOH at RBI was observed in another 7%. Moreover, a few tumours demonstrated a restricted deletion pattern, suggesting the presence of additional tumour-suppressor genes both proximal and distal of BRCA2. LOH at BRCA2 was significantly correlated to high S-phase values, low oestrogen and progesterone receptor content and DNA non-diploidy. LOH at BRCA2 was also associated, albeit non-significantly, with large tumour size and the ductal and medullar histological types. No correlation was found with lymph node status, patient age or a family history of breast cancer. A highly significant and independent correlation existed between LOH at BRCA2 and early recurrence and death. LOH at RBI was not associated with the above mentioned factors or prognosis. The present study does not provide conclusive evidence that BRCA2 is the sole target for deletions at 13q12-q13 in breast tumours. However, the results suggest that inactivation of one or several tumour-suppressor genes in the 13q12-q13 region confer a strong tumour growth potential and poor prognosis in both familial and sporadic breast cancer

On the biological relevance of MHC class II and B7 expression by tumour cells in melanoma metastases

A large number of studies have indicated that specific immune reactivity plays a crucial role in the control of malignant melanoma. In this context, expression of MHC I, MHC II and B7 molecules by melanoma cells is seen as relevant for the immune response against the tumour. For a better understanding of the biological relevance of MHC II and B7 expression by tumour cells in metastatic melanoma, we studied the expression of these molecules in melanoma metastases in relation to the inflammatory response, regression of the tumour and survival from 27 patients treated with biochemotherapy (30 mg m−2 Cisplatin and 250 mg m−2 decarbazine (dimethyl-triazene-imidazole-carboxamide, DTIC) on days 1–3 i.v., and 107 IU IFN-α2b 3 days a week s.c., q. 28d). In 19 out of 27 lesions studied, we found expression of MHC II by the tumour cells, while only in one out of 11 tumour biopsies obtained from untreated metastatic melanoma patients, MHC II expression was detected. Expression of B7.1 and B7.2 by tumour cells was found in nine out of 24 and 19 out of 24 lesions, respectively. In all cases where B7.1 expression was found, expression of B7.2 by the tumour cells was also seen. In general, no or only few inflammatory cells positive for B7 were found. Expression of MHC II by tumour cells was positively correlated with the presence of tumour-infiltrating lymphocytes, regression of the lesion, and with time to progression (TTP) and overall survival (OS) of the patient. However, no significant correlation between B7.1 or B7.2 expression and regression of the tumour, TTP or OS was found. In light of other recent findings, these data altogether do support a role as biomarker for MHC II expression by tumour cells; however, its exact immunological pathomechanism(s) remain to be established