Modeling of failure mode in knee ligaments depending on the strain rate

BACKGROUND: The failure mechanism of the knee ligament (bone-ligament-bone complex) at different strain rates is an important subject in the biomechanics of the knee. This study reviews and summarizes the literature describing ligament injury as a function of stain rate, which has been published during the last 30 years. METHODS: Three modes of injury are presented as a function of strain rate, and they are used to analyze the published cases. The number of avulsions is larger than that of ligament tearing in mode I. There is no significant difference between the number of avulsions and ligament tearing in mode II. Ligament tearing happens more frequently than avulsion in mode III. RESULTS: When the strain rate increases, the order of mode is mode I, II, III, I, and II. Analytical models of ligament behavior as a function of strain rate are also presented and used to provide an integrated framework for describing all of the failure regimes. In addition, this study showed the failure mechanisms with different specimens, ages, and strain rates. CONCLUSION: There have been several a numbers of studies of ligament failure under various conditions including widely varying strain rates. One issue in these studies is whether ligament failure occurs mid-ligament or at the bone attachment point, with assertions that this is a function of the strain rate. However, over the range of strain rates and other conditions reported, there has appeared to be discrepancies in the conclusions on the effect of strain rate. The analysis and model presented here provides a unifying assessment of the previous disparities, emphasizing the differential effect of strain rate on the relative strengths of the ligament and the attachment

Occurrence and overlap of natural disasters, complex emergencies and epidemics during the past decade (1995–2004)

BACKGROUND: The fields of expertise of natural disasters and complex emergencies (CEs) are quite distinct, with different tools for mitigation and response as well as different types of competent organizations and qualified professionals who respond. However, natural disasters and CEs can occur concurrently in the same geographic location, and epidemics can occur during or following either event. The occurrence and overlap of these three types of events have not been well studied. METHODS: All natural disasters, CEs and epidemics occurring within the past decade (1995–2004) that met the inclusion criteria were included. The largest 30 events in each category were based on the total number of deaths recorded. The main databases used were the Emergency Events Database for natural disasters, the Uppsala Conflict Database Program for CEs and the World Health Organization outbreaks archive for epidemics. ANALYSIS: During the past decade, 63% of the largest CEs had ≥1 epidemic compared with 23% of the largest natural disasters. Twenty-seven percent of the largest natural disasters occurred in areas with ≥1 ongoing CE while 87% of the largest CEs had ≥1 natural disaster. CONCLUSION: Epidemics commonly occur during CEs. The data presented in this article do not support the often-repeated assertion that epidemics, especially large-scale epidemics, commonly occur following large-scale natural disasters. This observation has important policy and programmatic implications when preparing and responding to epidemics. There is an important and previously unrecognized overlap between natural disasters and CEs. Training and tools are needed to help bridge the gap between the different type of organizations and professionals who respond to natural disasters and CEs to ensure an integrated and coordinated response

Antioxidant Protects against Increases in Low Molecular Weight Hyaluronan and Inflammation in Asphyxiated Newborn Pigs Resuscitated with 100% Oxygen

BACKGROUND: Newborn resuscitation with 100% oxygen is associated with oxidative-nitrative stresses and inflammation. The mechanisms are unclear. Hyaluronan (HA) is fragmented to low molecular weight (LMW) by oxidative-nitrative stresses and can promote inflammation. We examined the effects of 100% oxygen resuscitation and treatment with the antioxidant, N-acetylcysteine (NAC), on lung 3-nitrotyrosine (3-NT), LMW HA, inflammation, TNFα and IL1ß in a newborn pig model of resuscitation. METHODS & PRINCIPAL FINDINGS: Newborn pigs (n = 40) were subjected to severe asphyxia, followed by 30 min ventilation with either 21% or 100% oxygen, and were observed for the subsequent 150 minutes in 21% oxygen. One 100% oxygen group was treated with NAC. Serum, bronchoalveolar lavage (BAL), lung sections, and lung tissue were obtained. Asphyxia resulted in profound hypoxia, hypercarbia and metabolic acidosis. In controls, HA staining was in airway subepithelial matrix and no 3-NT staining was seen. At the end of asphyxia, lavage HA decreased, whereas serum HA increased. At 150 minutes after resuscitation, exposure to 100% oxygen was associated with significantly higher BAL HA, increased 3NT staining, and increased fragmentation of lung HA. Lung neutrophil and macrophage contents, and serum TNFα and IL1ß were higher in animals with LMW than those with HMW HA in the lung. Treatment of 100% oxygen animals with NAC blocked nitrative stress, preserved HMW HA, and decreased inflammation. In vitro, peroxynitrite was able to fragment HA, and macrophages stimulated with LMW HA increased TNFα and IL1ß expression. CONCLUSIONS & SIGNIFICANCE: Compared to 21%, resuscitation with 100% oxygen resulted in increased peroxynitrite, fragmentation of HA, inflammation, as well as TNFα and IL1ß expression. Antioxidant treatment prevented the expression of peroxynitrite, the degradation of HA, and also blocked increases in inflammation and inflammatory cytokines. These findings provide insight into potential mechanisms by which exposure to hyperoxia results in systemic inflammation

Politics of Care and Reverberations of Trauma: Syrian Refugees in Izmir, Turkey

For Syrians in Turkey, displacement produces new relationships to governance and forms of care. This dissertation explores a broad framework of international, national, and local institutions—including care and assistance sectors (health care and humanitarian aid), the labor market, and urban settlement—that are part of the interface between Syrians and the Turkish state. Displacement also causes new anxieties, fears, and shocks—from war trauma in Syria to refugee camps and homelessness in Turkey, from housing scarcity and income precarity to attempts at irregular migration by boat to Europe, from medicalized violence in giving birth and fears of dismemberment to local xenophobia and violence and ad hoc strategies for survival in the everyday. The broad question asked is: Why did Syrians experience Izmir as such a dangerous, necropolitical space, even though the government provided many services to enhance their lives, and even though they were supported by the dominant ruling government party? In answering this question, this dissertation studies the following fields: humanitarian programming, a history of migration in Izmir and contemporary gentrification practices, the unregulated labor sector, gender politics, health care services, the processing of refugee bodies, forensic medical practices, and cemeteries on the Aegean. Most importantly, this dissertation connects Syrian affects and emotions to the institutions that regulate their everyday lives through multiple interventions. Specifically, I ask: How can history, politics, and displacement be read in the feelings encoded in narratives of displacement and trauma? This historical timeline is related to four central dynamics: (1) The 2016 attempted coup and resulting state of emergency in Turkey; (2) the 2016 Turkey-EU deal; (3) the violence and policies of military incursions on the Turkey-Syria borderlands; and (4) necropolitics on the Turkey-Greece (EU) borderlands. All four dynamics limited Syrian movement within Turkey and along its increasingly securitized borders. In relation to examining those dynamics, this work takes inventory of Syrian politics and historicizes the experiences of Syrian refugees in Turkey. Population management and emerging biopolitical projects feature in this study as elements that organize Syrian lives in particular ways. Among other affects, shock or trauma, articulated in Arabic as sadma, is an important node of analysis for Syrian experiences of migration. Here, Syrian experiences of trauma become part of an “archive of feelings” (Cvetkovich, 2003) about the politics of displacement, connecting systemic structures of exploitation and oppression to the fears and dangers one feels and associates with everyday living in displacement. Emotional reverberations of fear are political, and Syrian affects in Turkey tell us about the politics of displacement in important ways

Experimental and theoretical investigation of the fracture behavior of glass beads/epoxy composites using microscratching

Abstract: Concrete, ceramic, and other quasi-brittle materials contain pre-existing cracks and complex structure on various internal length-scales. Quantifying the fracture behavior of these heterogeneous materials using different testing methods is a challenge and is an argumentative subjec

Green approaches in the synthesis of furan-based diepoxy monomers

Two eco-respectful, one-step synthetic routes for the preparation of a bio-based epoxy monomer derived from furan precursors are developed. The diglycidyl ester products are throughly characterized in terms of structure and thermal properties. Gathered results indicate that the two selected approaches allow the preparation of pure, furanic diglycidyl ester, which represents a viable bio-based alternative to its petrochemical aromatic counterpart. © 2018 The Royal Society of Chemistry

Green approaches in the synthesis of furan-based diepoxy monomers

Two eco-respectful, one-step synthetic routes for the preparation of a bio-based epoxy monomer derived from furan precursors are developed. The diglycidyl ester products are throughly characterized in terms of structure and thermal properties. Gathered results indicate that the two selected approaches allow the preparation of pure, furanic diglycidyl ester, which represents a viable bio-based alternative to its petrochemical aromatic counterpart

Green approaches in the synthesis of furan-based diepoxy monomers

Two eco-respectful, one-step synthetic routes for the preparation of a bio-based epoxy monomer derived from furan precursors are developed. The diglycidyl ester products are throughly characterized in terms of structure and thermal properties. Gathered results indicate that the two selected approaches allow the preparation of pure, furanic diglycidyl ester, which represents a viable bio-based alternative to its petrochemical aromatic counterpart. © 2018 The Royal Society of Chemistry

Correlation of optic nerve and optic nerve sheath diameter with intracranial pressure in pigs.

OBJECTIVE Several studies have shown an association between intracranial pressure and the diameter of the optic nerve sheath measured by transbulbar ultrasonography. To understand the pathophysiology of this phenomenon, we aimed to measure the changes of the optic nerve, optic nerve sheath and perineural space separately with increasing intracranial pressure in a porcine model. METHODS An external ventricular drain was placed into the third ventricle through a right paramedian burrhole in eight anesthesized pigs. The diameters of the optic nerve and the optic nerve sheath were measured while the intracranial pressure (ICP) was increased in steps of 10mmHg from baseline up to 60 mmHg. RESULTS The median diameters of the optic nerve (ON) increased from 0.36 cm (baseline- 95% confidence interval (CI) 0.33 cm to 0.45 cm) to 0.68 cm (95% CI 0.57 cm to 0.82 cm) at ICP of 60 mmHg (p<0.0001) and optic nerve sheath (ONS) from 0.88 cm (95% CI 0.79 cm to 0.98 cm) to 1.24 cm (95% CI 1.02 cm to 1.38 cm) (p< 0.002) while the median diameter of the perineural space (PNS) (baseline diameter 95% CI 0.40 cm to 0.59 cm to diameters at ICP 60 95% CI 0.38 cm to 0.62 cm) did not change significantly (p = 0.399). Multiple comparisons allowed differentiation between baseline and values ≥40 mmHg for ON (p = 0.017) and between baseline and values ≥ 50mmHg for ONS (p = 0.006). A linear correlation between ON (R2 = 0.513, p<0.0001) and ONS (R2 = 0.364, p<0.0001) with ICP was found. The median coefficient of variation for intra- and inter-investigator variability was 8% respectively 2.3%. CONCLUSION Unexpectedly, the increase in ONS diameter with increasing ICP is exclusively related to the increase of the diameter of the ON. Further studies should explore the reasons for this behaviour