The Fracture Toughness of Ice in Contact with Salt Water

Experiments have established that the fracture toughness of fresh-water, bubbly ice is not affected by the presence of salt water. THIS note considers whether the resistance of ice to fast crack propagation, or the fracture toughness, is affected by water. The question arises because ice frequently breaks in the presence of water (icebergs, ice covers, and salt-water ice which contains brine-filled pores) and because surface energy, which is reduced upon wetting, is the primary barrier (Gold, 1963; Nixon and Schulson, 1987) to fast crack propagation. Earlier work along these Lines (Liu and Miller, 1979) was characterized by scatter and thus did not permit a firm conclusion. To explore this point, doubly notched cylindrical specimens of isotropic ice were employed. The double-notched configuration eliminates scatter caused by specimen-to-specimen variations. The ice from which the specimens were made was produced by flooding snow with Hanover tap water and allowing the mixture to freeze in uninsulated tubs situated within a cold room at -10 QC. The snow had been harvested after a fresh fall during the winter of 1988. The ice was finely grained (1-3 mm) and bubbly. The latter characteristic was manifested by an opaque appearance and by a relatively low density (880 ± 20 kg / m 3 vs 917 kg / m 3 for bubble-free, fresh-water ice). The specimens were prepared by coring cylinders (102 mm diameter by 250 mm) from the snow ice. Carpet-backed, phenolic end caps were bonded to the cylinders (see Lee, 1986) to allow attachment to the test machine. The specimens were then circumferentially notched to a depth of 9. 91 mm and sharpened to an additional depth of 0.254 mm. The sharpening was performed with a fresh razor blade held in the tool post of a lathe. The cutting was performed at -2 QC, once the ice and the tools had reached this temperature, after which thin (0.22 mm) rubber sleeves were slipped over each notch. The spacing of the notches was lOO mm for all specimens (see Fig. I). Subsequently, the specimens were mounted in the testing machine (a servohydraulic MTS housed within a cold-room) and lightly pre-loaded (~l 00 N) for about 10 s. Salt (NaCl) water of salinity 35 ppt, brought into equilibrium with ice at -2 QC by holding in its container until a thin layer of ice formed, was then injected using a squeegy bottle to fill the space behind one of the sleeves. The specimens were immediately loaded in tension at a constant stress-intensity rate of either 10 kPa mt S- 1 or 1000 kPa mt S-1 until fracture. The loading times depended on the fracture toughness, but were of the order of 10 s at the lower rate and 0.1 s at the higher rate. To reduce any possible effects of time on notch acuity, sharpening was performed immediately after notching and testing was performed within a few minutes (-3-4) of sharpening. The sequence was completed before the next specimen was notched. Table I summarizes the results. Of the ten specimens fractured at the lower rate, seven broke at the wet notch and three broke at the dry notc\ The fracture toughnfsses, respectively, were 136 ± 25 kPa m and 134 ± 35 kPa m. Of a b Fig. 1. Photographs showillg doubly Ilo/ched specim en XCB ( a ) loaded ill tellsioll alld ( b) brokell. Fra c/ure oc curred a/ the dry Ilo/ch. Th e Ic oa/ioll 0/ the Ilo/che s ill this specimell is typical of the locatioll in every specimen. the ten specimens fractured at the higher rate, five broke at the wet notch and five broke at the dry notch. In these cases the fra¥ture toughnesses were 82 ± 10 kPa m t and lOO ± 9 kPa m , respectively. The reduction in toughness at the higher rate reflects the behavior of bubble-free, fresh-water granular ice (Nixon and Schulson, 1987) and, as discussed in that reference, is attributed to the suppression of crack-tip creep deformation. Examination of broken specimens under a stereographic microscope revealed little , if any, rounding of the wet notches. This observation thus renders improbable the possibility that blunting through dissolution within the notch may have compensated for a lowered toughness in :he presence of the water. Observations by eye revealed a transgranular or cleavage mode of fracture. It is concluded, therefore, that fast crack propagation through ice is not significantly affected by the presence of salt water, when the ice and the water are in equilibrium. Wetting must thus act as a post-cracking phenomenon in that the speed of its occurrence is insufficient to lower the energy barrier to propagation

Does an Interactive Health Promotion Website Facilitate Workplace Peer-to-Peer Substance Abuse Prevention?

Operation RedBlock, a substance abuse prevention and early intervention program at Amtrak, implemented an interactive health promotion website (On The Right Track, OTRT) for its volunteers, other employees and their families. OTRT was customized from the Substance Abuse and Mental Health Services Administration (SAMHSA) -sponsored [email protected] website and implemented with the purpose of facilitating the peer-to-peer substance abuse prevention efforts of Operation RedBlock volunteers. SAMHSA’s GetFit website combines broad health and wellness messages with current substance abuse prevention resources. The OTRT customization adds Amtrak relevant and specific content concerning substance abuse prevention resources and treatment options, drug and alcohol use policies, health care coverage, support group meeting locations and dates, and local Operation RedBlock and Employee Assistance Program contact information. Using a retrospective pretest-posttest design this study evaluates whether and how OTRT facilitated peer-to-peer efforts in substance abuse prevention and early intervention. The evaluation revealed that the website significantly improved access to information and resources that helped Operation RedBlock volunteers’ in their peer-to-peer efforts. Volunteers valued the ready availability of reliable information, the confidential nature, and the ease of use of OTRT. Facilitated access to information and resources may help reduce substance abuse among employees at high risk

Transformation kinetics of alloys under non-isothermal conditions

The overall solid-to-solid phase transformation kinetics under non-isothermal conditions has been modeled by means of a differential equation method. The method requires provisions for expressions of the fraction of the transformed phase in equilibrium condition and the relaxation time for transition as functions of temperature. The thermal history is an input to the model. We have used the method to calculate the time/temperature variation of the volume fraction of the favored phase in the alpha-to-beta transition in a zirconium alloy under heating and cooling, in agreement with experimental results. We also present a formulation that accounts for both additive and non-additive phase transformation processes. Moreover, a method based on the concept of path integral, which considers all the possible paths in thermal histories to reach the final state, is suggested.Comment: 16 pages, 7 figures. To appear in Modelling Simul. Mater. Sci. En

GYNOCARE Update: Modern Strategies to Improve Diagnosis and Treatment of Rare Gynecologic Tumors—Current Challenges and Future Directions

More than 50% of all gynecologic tumors can be classified as rare (defined as an incidence of ≤6 per 100,000 women) and usually have a poor prognosis owing to delayed diagnosis and treatment. In contrast to almost all other common solid tumors, the treatment of rare gynecologic tumors (RGT) is often based on expert opinion, retrospective studies, or extrapolation from other tumor sites with similar histology, leading to difficulty in developing guidelines for clinical practice. Currently, gynecologic cancer research, due to distinct scientific and technological challenges, is lagging behind. Moreover, the overall efforts for addressing these challenges are fragmented across different European countries and indeed, worldwide. The GYNOCARE, COST Action CA18117 (European Network for Gynecological Rare Cancer Research) programme aims to address these challenges through the creation of a unique network between key stakeholders covering distinct domains from concept to cure: basic research on RGT, biobanking, bridging with industry, and setting up the legal and regulatory requirements for international innovative clinical trials. On this basis, members of this COST Action, (Working Group 1, “Basic and Translational Research on Rare Gynecological Cancer”) have decided to focus their future efforts on the development of new approaches to improve the diagnosis and treatment of RGT. Here, we provide a brief overview of the current state-of-the-art and describe the goals of this COST Action and its future challenges with the aim to stimulate discussion and promote synergy across scientists engaged in the fight against this rare cancer worldwide

Characterization and Whole Genome Analysis of Human Papillomavirus Type 16 E1-1374^63nt Variants

Background. The variation of the most common Human papillomavirus (HPV) type found in cervical cancer, the HPV16, has been extensively investigated in almost all viral genes. The E1 gene variation, however, has been rarely studied. The main objective of the present investigation was to analyze the variability of the E6 and E1 genes, focusing on the recently identified E1-1374^63nt variant. Methodology/Principal Findings. Variation within the E6 of 786 HPV16 positive cervical samples was analyzed using high-resolution melting, while the E1-1374^63nt duplication was assayed by PCR. Both techniques were supplemented with sequencing. The E1-1374^63nt duplication was linked with the E-G350 and the E-C109/G350 variants. In comparison to the referent HPV16, the E1-1374^63nt E-G350 variant was significantly associated with lower grade cervical lesions (p=0.029), while the E1-1374^63nt E-C109/G350 variant was equally distributed between high and low grade lesions. The E1-1374^63nt variants were phylogenetically closest to E-G350 variant lineage (A2 sub-lineage based on full genome classification). The major differences between E1-1374^63nt variants were within the LCR and the E6 region. On the other hand, changes within the E1 region were the major differences from the A2 sub-lineage, which has been historically but inconclusively associated with high grade cervical disease. Thus, the shared variations cannot explain the particular association of the E1-1374^63nt variant with lower grade cervical lesions. Conclusions/Significance. The E1 region has been thus far considered to be well conserved among all HPVs and therefore uninteresting for variability studies. However, this study shows that the variations within the E1 region could possibly affect cervical disease, since the E1-1374^63nt E-G350 variant is significantly associated with lower grade cervical lesions, in comparison to the A1 and A2 sub-lineage variants. Furthermore, it appears that the silent variation 109T>C of the E-C109/G350 variant might have a significant role in the viral life cycle and warrants further study

Diarrhoea in the critically ill is common, associated with poor outcome, and rarely due to Clostridium difficile

Diarrhoea is common in Intensive Care Unit (ICU) patients, with a reported prevalence of 15-38%. Many factors may cause diarrhoea, including Clostridium difficile, drugs (e.g. laxatives, antibiotics) and enteral feeds. Diarrhoea impacts on patient dignity, increases nursing workload and healthcare costs, and exacerbates morbidity through dermal injury, impaired enteral uptake and subsequent fluid imbalance. We analysed a cohort of 9331 consecutive patients admitted to a mixed general intensive care unit to establish the prevalence of diarrhoea in intensive care unit patients, and its relationship with infective aetiology and clinical outcomes. We provide evidence that diarrhoea is common (12.9% (1207/9331) prevalence) in critically ill patients, independently associated with increased intensive care unit length of stay (mean (standard error) 14.8 (0.26) vs 3.2 (0.09) days, p < 0.001) and mortality (22.0% (265/1207) vs 8.7% (705/8124), p < 0.001; adjusted hazard ratio 1.99 (95% CI 1.70-2.32), p < 0.001) compared to patients without diarrhoea even after adjusting for potential confounding factors, and infrequently caused by infective aetiology (112/1207 (9.2%)) such as Clostridium difficile (97/1048 (9.3%) tested) or virological causes (9/172 (5.7%) tested). Our findings suggest non-infective causes of diarrhoea in ICU predominate and pathophysiology of diarrhoea in critically ill patients warrants further investigation

The contribution of inherited genotype to breast cancer

The etiology of breast cancer is complex, and is likely to involve the actions of genes at multiple levels along the multistage carcinogenesis process. These inherited genotypes include those that affect the propensity to be exposed to breast carcinogens, and those associated with breast tumorigenesis directly. In addition, inherited genotypes may influence response to breast cancer chemoprevention and treatment. Studies relating inherited genotypes with breast cancer incidence and mortality should consider a broader spectrum of genes and their potential roles in multistage carcinogenesis than have been typically evaluated to date. Understanding the role of inherited genotype at different stages of carcinogenesis could improve our understanding of cancer biology, may identify specific exposures or events that correlate with carcinogenesis, or target relevant biochemical pathways for the development of preventive or therapeutic interventions

Standard of civilization, nomadism and territoriality in nineteenth-century international society

In this chapter, the encounter between the Russian Empire and the nomads of the Eurasian steppe in the nineteenth century is analyzed using the theoretical framework of the standard of civilization. The creation of the Westphalian state-model in Europe in the seventeenth century, linked to the later emergence of the notion of the standard of civilization led to the ‘othering’ of the nomads of the Eurasian steppe as barbarians, as a threat to the borders of civilized Europe. The chapter presents also an argument to define ‘territoriality’ as not only an institution of international society of the time but also as a distinctive quality and requirement for being considered ‘civilized’. In this analytical framework, the nomads become the ‘other’, the ‘alien’, the ‘menace’, onto which projections of rationality and modernity were cast in order to prevent threats to Russia’s European and civilized identity. The chapter sheds light on the encounter between ‘fixed’ and ‘mobile’ units in the course of expansion of international society; contextualizes the role played by nomadic tribes in resisting the application of Westphalian spatial categories in the Eurasian space; and scrutinizes what the role of nomads was in constructing a European, civilized identity.PostprintPeer reviewe

Early Trauma and Increased Risk for Physical Aggression during Adulthood: The Moderating Role of MAOA Genotype

Previous research has reported that a functional polymorphism in the monoamine oxidase A (MAOA) gene promoter can moderate the association between early life adversity and increased risk for violence and antisocial behavior. In this study of a combined population of psychiatric outpatients and healthy volunteers (N = 235), we tested the hypothesis that MAOA genotype moderates the association between early traumatic life events (ETLE) experienced during the first 15 years of life and the display of physical aggression during adulthood, as assessed by the Aggression Questionnaire. An ANOVA model including gender, exposure to early trauma, and MAOA genotype as between-subjects factors showed significant MAOA×ETLE (F1,227 = 8.20, P = 0.005) and gender×MAOA×ETLE (F1,227 = 7.04, P = 0.009) interaction effects. Physical aggression scores were higher in men who had experienced early traumatic life events and who carried the low MAOA activity allele (MAOA-L). We repeated the analysis in the subgroup of healthy volunteers (N = 145) to exclude that the observed G×E interactions were due to the inclusion of psychiatric patients in our sample and were not generalizable to the population at large. The results for the subgroup of healthy volunteers were identical to those for the entire sample. The cumulative variance in the physical aggression score explained by the ANOVA effects involving the MAOA polymorphism was 6.6% in the entire sample and 12.1% in the sub-sample of healthy volunteers. Our results support the hypothesis that, when combined with exposure to early traumatic life events, low MAOA activity is a significant risk factor for aggressive behavior during adulthood and suggest that the use of dimensional measures focusing on behavioral aspects of aggression may increase the likelihood of detecting significant gene-by-environment interactions in studies of MAOA-related aggression