霍金新书称宇宙非上帝创造(英文)

God did not create the universe and the"Big Bang"was an inevitable consequence of the laws of physics,the eminent British theoretical physicist Stephen Hawking argues in a new book.

Static and dynamic tensile failure characteristics of rock based on splitting test of circular ring

Static and dynamic splitting tests were conducted on ring marble specimens with different internal diameters to study the tensile strength and failure modes with the change of the ratio of internal radius to external radius （ρ） under different loading rates. The results show that the dynamic tensile strength of disc rock specimen is approximately five times its static tensile strength. The failure modes of ring specimens are related to the dimension of the internal hole and loading rate. Under static loading tests, when the ratio of internal radius to external radius of the rock ring is small enough （ρ〈0.3）, specimens mostly split along the diametral loading line. With the increase of the ratio, the secondary cracks are formed in the direction perpendicular to the loading line. Under dynamic loading tests, specimens usually break up into four pieces. When the ratio ρreaches 0.5, the secondary cracks are formed near the input bar. The tensile strength calculated by Hobbs’ formula is greater than the Brazilian splitting strength. The peak load and the radius ratio show a negative exponential relationship under static test. Using ring specimen to determine tensile strength of rock material is more like a test indicator rather than the material properties.

Evaluation of dynamic performance and ballistic behavior of Ti-5Al-5Mo-5V-3Cr-1Zr alloy

Terminal ballistic tests using 7.62 mm armor-piercing incendiary （API） projectiles were performed to evaluate the resistance to penetration of Ti-5Al-5Mo-5V-3Cr-IZr （Ti-55531） alloy. The dynamic properties were determined by a split Hopkinson pressure bar （SHPB） test system. Ti-55531 plates were subjected to two kinds of heat treatments, leading to the formation of high-strength and high-toughness plates. The results of SHPB test exhibit that the maximum impact absorbed energy of the high-strength plate at a strain rate of 2200 s^-1 is 270 MJ/m^3; however, the maximum value for the high-toughness plate at a strain rate of 4900 s^-1 is 710 MJ/m^3. The ballistic limit velocities for the high-strength and high-toughness plates with dimensions of 300 mm×300 mm×8 mm are 330 and 390 m/s, respectively. Excellent dynamic properties of Ti-55531 alloy correspond to good resistance to penetration. The microstructure evolution related to various impact velocities are observed to investigate the failure mechanism.

Dynamic mechanical properties and instability behavior of layered backfill under intermediate strain rates

To obtain dynamic mechanical properties and failure rule of layered backfill under strain rates from10to80s-1,impactloading test on layered backfill specimens(LBS)was conducted by using split Hopkinson pressure bar system.The results indicatethat positive correlation can be found between dynamic compressive strength and strain rate,as well as between strength increasefactor and strain rate.Dynamic compressive strength of LBS gets higher as the arithmetic average cement-sand ratio increases.Compared with static compressive strength,dynamic compressive strength of LBS is enhanced by11%to163%.In addition,theenergy dissipating rate of LBS lies between that of corresponding single specimens,and it decreases as the average cement contentincreases.Deformation of LBS shows obvious discontinuity,deformation degree of lower strength part of LBS is generally higherthan that of higher strength part.A revised brittle fracture criterion based on the Stenerding-Lehnigk criterion is applied to analyzingthe fracture status of LBS,and the average relevant errors of the3groups between the test results and calculation results are4.80%,3.89%and4.66%,respectively.

Dynamic tensile behavior of PM Ti-47Al-2Nb-2Cr-0.2W intermetallics at elevated temperatures

Split Hopkinson Tension Bar(SHTB) experiments were conducted to explore the dynamic mechanical behavior and deformation mechanism of powder metallurgical(PM) Ti-47 Al-2 Nb-2 Cr-0.2 W(at.%)intermetallics with near lamellar(NL) and duplex(DP)microstructures. Results show that,under dynamic loading,the high temperature strength of the PM TiAl intermetallics is higher than that under quasi-static loading, and the ductile to brittle transition temperature(DBTT) increases with the increase of strain rate. Formation of twinning and stacking faults is the main deformation mechanism during dynamic loading. The work hardening rates of the PM TiAl intermetallics are nearly insensitive to strain rate and temperature at high strain rates(800-1600 s-1)and high temperatures(650-850 ℃). Zerilli-Armstrong model is successfully used to describe the dynamic flowing behavior of the PM TiAl intermetallics. In general, the PM TiAl intermetallics are found to have promising impact properties, suitable for high-temperature and high-impact applications.

Relationship between diameter of split Hopkinson pressure bar and minimum loading rate under rock failure

In order to investigate the relationship between bar diameter and loading rate of the split Hopkinson pressure bar(SHPB) setup under the failure of rock specimen and realize the medium strain rate loading of specimen,new SHPB setups with different elastic bar's diameters of 22,36,50 and 75 mm were constructed.The tests were carried out on these setups at different loading rates,and the specimens had the same diameter of elastic bars and same ratio of length to diameter.The test results show that the larger the elastic bar's diameter is,the less the loading rate is needed to cause specimen failure,they show good power relationship,and that under the same strain rate loading,specimens are broken more seriously with larger diameter SHPB setup than with smaller one.

Primary early-stage intestinal and colonic non-Hodgkin's lymphoma: Clinical features, management, and outcome of 37 patients

AIM： To analyze the clinical features, management, and outcome of treatment of patients with primary intestinal and colonic non-Hodgkin＇s lymphoma （PICL）. METHODS： A retrospective study was performed in 37 patients with early-stage PICL who were treated in our hospital from 1958 to 1998. Their clinical features, management, and outcome were assessed. Prognostic factors for survival were analyzed by univariate analysis using the Kaplan-Meier product-limit method and log-rank test. RESULTS： Twenty-five patients presented with Ann Arbor stage Ⅰ PICL and 12 with Ann Arbor stage Ⅱ PICL. Thirty-five patients underwent surgery （including 31 with complete resection）, 22 received postoperative chemotherapy or radiotherapy or both. Two patients with rectal tumors underwent biopsy and chemotherapy with or without radiotherapy. The 5- and 10-year overall survival （OS） rates were 51.9% and 44.5%. The corresponding diseasefree survival （DIS） rates were 42.4% and 37.7%. In univariate analysis, multiple-modality treatment was associated with a better DFS rate compared to single treatment （P= 0.001）. While age, tumor size, tumor site, stage, histology, or extent of surgery were not associated with OS and DFS, use of adjuvant chemotherapy significantly improved DFS （P = 0.031） for the 31 patients who underwent complete resection. Additional radiotherapy combined with chemotherapy led to a longer survival than chemotherapy alone in six patients with gross residual disease after surgery or biopsy.CONCLUSION： Combined surgery and chemotherapy is recommended for treatment of patients with PICL, Additional radiotherapy is needed to improve the outcome of patients who have gross residual disease after surgery.

Correction to Hawking Tunneling Radiation from Global Monopole Charged BlackHole

Considering the self-gravitation and energy conservation as well as charge conservation, we extend Medved and Vagenas＇s quantum tunneling method to the global monopole charged black hole, and give a correction to Hawking radiation of a charged particle.

Primary pancreatic lymphoma: Report of six cases

AIM： To heighten recognition of primary pancreatic lymphoma （PPL） in clinical practice. METHODS： A retrospective review of the clinical presentation, imaging characteristics and pathological features of PPL patients were presented, as well as their diagnosis and treatment, in combination with literature review. RESULTS： Histological diagnosis was made in four patients by surgery and in two patients by EUS-FNA. The six PPL patients （5 males and 1 female; age range, 16-65 years; mean age, 46 years） had the duration of symptoms for two weeks to three months. The primary presenting symptoms, though not characteristic, were abdominal pain, abdominal masses, weight loss, jaundice, nausea and vomiting. One of the patients developed acute pancreatitis. In one patient, the level of serum CA19-9 was 76.3 μg/L. Abdominal CT scan showed that three of the six tumors were located in the head of pancreas, two in the body and tail, and one throughout the pancreas. Diameter of the tumors in the pancreas in four cases was more than 6 cm, with homogeneous density and unclear borders. Enhanced CT scan showed that only the tumor edges were slightly enhanced. The pancreatic duct was irregularly narrowed in two cases whose tumors were located in the pancreatic head and body, in which endoscopic retrograde cholangiopancreatography （ERCP） showed that the proximal segment was slightly dilated. Two patients underwent Whipple operation, one patient underwent pancreatectomy, and another patient underwent operative biliary decompression. PPL was in stage Ⅰ E in 2 patients and in stage Ⅱ E in 4 patients according to the Ann Arbor classification system. The diagnosis of B-cell non-Hodgkin＇s lymphoma was made in all patients histopathologically. All six patients underwent systemic chemotherapy, one of whom was also treated with gamma radiometry. One patient died two weeks after diagnosis, two patients lost follow-up, two patients who received chemotherapy survived 49 and 37 mo, and the remaining patient is still alive 21 mo, after diagnosis and treatment. CONCLUSION： PPL is a rare form of extranodal lymphoma originating from the pancreatic parenchyma. Clinical and imaging findings are otherwise not specific in the differentiation of pancreatic lymphoma and pancreatic cancer, which deserves attention. EUS-guided fine-needle aspiration （EUS-FNA） of the pancreas requires experienced cytopathologists as well as advanced immunohistochemical assays to obtain a final diagnosis on a small amount of tissue. Surgery and adjuvant chemotherapy or radiotherapy can produce fairly good outcomes.

Hawking Radiation of Charged Particles in Reissner-Nordstrm Black Hole

We extend the method that Banerjee and Majhi have used to discuss Hawking radiation. Under the condition that the total energy and electrical charge of spacetime are conserved, we investigate Hawking radiation of the charged black hole by a new Tortoise coordinate transformation. Taking the reaction of the radiation of the particle to the spacetime into consideration, we not only derive the radiation spectrum that satisfies the unitary principle in quantum mechanics but also show that the contribution of ingoing particles is equal to the one of outgoing particles on the similar chemical potential term in radiation spectrum caused by charged particles.

Combined effects of temperature and axial pressure on dynamic mechanical properties of granite

In order to get the dynamic mechanical properties of deep rock mass suffered both high temperature and high pressure,impact loading experiments on granite subjected to temperature and axial pressure were carried out. Furthermore, the internalstructure characteristics of granite under different temperatures were observed by scanning electron microscopy (SEM). The results show that the longitudinal wave velocity assumes a downward trend which shows a rapid drop before falling slowly as the temperature increases. The uniaxial compressive strength of the specimen decreases significantly at temperatures of 25?100 °C compared to that at temperatures of 100?300 °C. The peak strain rises rapidly before the dividing point of 100 °C, but increases slowly after the dividing point. The internal structure of the rock changes substantially as the temperature increases, such as the extension and transfixion of primary and newborn cracks. In addition, the thermal damage under axial pressure is greater than that described by the longitudinal wave velocity and the phenomenon shows obviously when the temperature increases.

Physical and dynamic mechanical behaviors of marble after heat treatment in quasi-vacuum and air-filled environments

The dynamic mechanical properties of rock specimens after thermal treatment in the air-filled environment(AE:i.e.,at the free surface)have been extensively investigated,yet they are rarely estimated in the quasi-vacuum environment(VE:i.e.,far from free surface),which is of special importance in engineering practice.Several precise laboratory tests(i.e.,split Hopkinson pressure bar test)on marble samples in both AE and VE were performed to investigate physical and dynamic mechanical behaviors of marble after heat treatment(25℃ to 900℃)in AE and VE.The tests results demonstrate that related properties of marble could be divided into three different stages by corresponding critical temperatures of 300℃ and 600℃,at which heat damage factors are 0.29(0.30)and 0.88(0.92)in VE(AE),respectively.The thermal damage developes more fully in AE than in VE.The thermal environment plays an important role,especially in Stage 3.Specifically,a conspicuous difference(greater than 20%)between AE and VE occurs in corresponding dynamic strength and the anti-deformation capacities of tested marble specimen.The influence of heat damage of rock is very important and valuable in engineering practice,particularly when the temperature is very high(greater than 600℃).

Secondary pancreatic involvement by a diffuse large B-cell lymphoma presenting as acute pancreatitis

Diffuse large B-cell lymphoma is the most common type of non-Hodgkin's lymphoma. More than 50% of patients have some site of extra-nodal involvement at diagnosis, including the gastrointestinal tract and bone marrow. However, a diffuse large B-cell lymphoma presenting as acute pancreatitis is rare. A 57-year-old female presented with abdominal pain and matted lymph nodes in her axilla. She was admitted with a diagnosis of acute pancreatitis. Abdominal computed tomography (CT) scan showed diffusely enlarged pancreas due to infiltrative neoplasm and peripancreatic lymphadenopathy. Biopsy of the axillary mass revealed a large B-cell lymphoma. The patient was classified as stage Ⅳ, based on the Ann Arbor Classification, and as having a high-risk lymphoma, based on the International Prognostic Index. She was started on chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone). Within a week after chemotherapy, the patient’s abdominal pain resolved. Follow-up CT scan of the abdomen revealed a marked decrease in the size of the pancreas and peripancreatic lymphadenopathy. A literature search revealed only seven cases of primary involvement of the pancreas in B-cell lymphoma presenting as acute pancreatitis. However, only one case of secondary pancreatic involvement by B-cell lymphoma presenting as acute pancreatitis has been published. Our case appears to be the second report of such a manifestation. Both cases responded well to chemotherapy.

Experimental study on mechanical properties of modified polytetrafluoroethylene

In order to study the mechanical properties of modified low-density polytetrafluoroethylene （PTFE）, universal testing machine is used for quasi-static tension and compression tests and Hopkinson bar test is for mechanical property under impact load. The mechanical properties of the samples with different length-diameter ratios under different impact loads are analyzed and dynamic response characteristics of the modified PTFE at different impact speeds are studied. The results show that, adding the copper powder in PTFE material can increase not only the tensile strength and elongation of the PTFE material sig- nificantly, but also the compressive strength; with the increase of strain rate, the yield strength of modified PTFE increases.

Molecular markers(PECAM-1,ICAM-3,HLA-DR)determine prognosis in primary non-Hodgkin's gastric lymphoma patients

AIM： To investigate the prognostic significance of PECAM-1, ICAM-3 and HLA-DR antigens in patients with primary non-Hodgkin＇s gastric lymphoma. METHODS： We immunohistochemically studied PECAM-1, ICAM-3 and HLA-DR antigen expression in 36 B-cell MALT-type primary gastric lymphoma patients. Ten non-malignant and ten healthy gastric tissue specimens were used as controls. Clinicopathological and survival data were correlated with the staining results. RESULTS： HLA-DR antigen expression was detected in 33 gastric lymphoma patients （91.7%） and 6 nonmalignant patients （54.5%）. PECAM-1 stained tumor cells of 10 patients （27.8%）, endothelial cells of 9 patients （25%） and inflammatory infiltrate of 4 patients （40%） with benign gastric disease. ICAM-3 expression was observed on the tumor cells of 17 patients （47.2%）, while 5 non-malignant patients （50%） were stained positive as well. None of the healthy controls was stained for any of the genes studied. In the multivariate analysis, HLA-DR antigen and PECAM-1 were proved to be statistically significant independent prognostic factors associated with a favourable and an unfavourable prognosis respectively （P= 0.009 and P= 0.003）. In the univariate analysis, PECAM-1（＋）/ICAM-3（-） and HLA-DR（-）/ICAM-3（-） patients exhibited a significantly decreased overall survival compared to those with the exactly opposite gene expression patterns （P=0.0041 and P= 0.0091, respectively）. Those patients who were HLA-DR（＋ ）/ICAM-3（＋ ）/PECAM-I（-） （n = 8） had a significantly higher survival rate compared to the rest of the group （n = 24） （P= 0.0289）. CONCLUSION： PECAM-1, ICAM-3 and HLA-DR are representative markers of tumor expansion potential and host immune surveillance respectively. Their combined use may help us to identify high-risk patients who could benefit from more aggressive therapeutic protocols.

Tunneling Through Black Rings

Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzed by use of the Parikh-Wilczek tunneling method. To get the correct tunneling amplitude and emission rate, we adopt and develop the Angheben-Nadalini-Vanzo Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitutes a unified approach to the tunneling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agrees exactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

Failure of rock under dynamic compressive loading

Split Hopkinson Pressure Bar(SHPB) test was simulated to investigate the distribution of the first principal stress and damage zone of specimen subjected to dynamic compressive load. Numerical models of plate-type specimen containing cracks with inclined angles of 0°,45° and 90° were also established to investigate the crack propagation and damage evolution under dynamic loading. The results show that the simulation results are in accordance with the failure patterns of specimens in experimental test. The interactions between stress wave and crack with different inclined angles are different; damage usually appears around the crack tips firstly; and then more damage zones develop away from the foregoing damage zone after a period of energy accumulation; eventually,the damage zones run through the specimen in the direction of applied loading and split the specimen into pieces.

Dirac Particles' Tunneling Radiation from Dilaton Space-time with Squashed Horizons

The aim of this paper is to investigate Hawking radiation of Dirac particles from the Dilaton space-time with squashed horizons by improving the method of Kerner and Man’s tunneling analysis.We construct appropriate matrices for general covariant Dirac equation,and derive the tunneling probability and Hawking temperature.The results show that both Dirac particles and scalar particles radiate at the same Hawking temperature.

Damage constitutive model of different age concretes under impact load

In order to investigate the mechanical properties and stress-strain curves of concrete at different ages under impact load,the impact compression tests of concrete at age of 1, 3, 7, 14 and 28 d were conducted with a large diameter split Hopkinson pressure bar, respectively. Based on statistical damage theory and Weibull distribution, combining the analysis of the change laws of stressstrain curves and viscosity coefficient of concrete with age, a damage constitutive model that can reflect the variation in dynamic mechanical properties with age was proposed. The stress-strain curves calculated from the proposed model are in good agreement with those from experimental data directly.