Simulating spatial and temporal evolution of multiple wing cracks around faults in crystalline basement rocks

Fault zones are structurally highly spatially heterogeneous and hence extremely complex. Observations of fluid flow through fault zones over several scales show that this structural complexity is reflected in the hydrogeological properties of faults. Information on faults at depth is scarce, hence, it is highly valuable to understand the controls on spatial and temporal fault zone development. In this paper we increase our understanding of fault damage zone development in crystalline rocks by dynamically simulating the growth of single and multiple splay fractures produced from failure on a pre-existing fault. We present a new simulation model, MOPEDZ (Modeling Of Permeability Evolution in the Damage Zone surrounding faults), that simulates fault evolution through solution of Navier's equation with a combined Mohr-Coulomb and tensile failure criteria. Simulations suggest that location, frequency, mode of failure and orientation of splay fractures are significantly affected both by the orientation of the fault with respect to the maximum principal compressive stress and the conditions of differential stress. Model predictions compare well with published field outcrop data, confirming that this model produces realistic damage zone geometries

Polymorph exploration of bismuth stannate using first-principles phonon mode mapping

Accurately modelling polymorphism in crystalline solids remains a key challenge in computational chemistry. In this work, we apply a theoretically-rigorous phonon mode-mapping approach to understand the polymorphism in the ternary metal oxide Bi2Sn2O7. Starting from the high-temperature cubic pyrochlore aristotype, we systematically explore the structural potential-energy surface and recover the two known low-temperature phases alongside three new metastable phases, together with the transition pathways connecting them. This first-principles lattice-dynamics method is completely general and provides a practical means to identify and characterise the stable polymorphs and phase transitions in materials with complex crystal structures

Goals of Care 101

Hospice and Palliative Medicine - Alexandra Evans, DO Approaching Goals of Care in the Outpatient World - Elham Siddiqui, MD Inpatient Goals of Care Discussion - Adam Pennarola, M

Timing of Fluoride Intake and Dental Fluorosis On Late-Erupting Permanent Teeth

Objective: Very few studies have examined the relationship between timing of fluoride intake and development of dental fluorosis on late-erupting permanent teeth using period-specific fluoride intake information. This study examined this relationship using longitudinal fluoride intake information from the Iowa Fluoride Study. Methods: Participants’ fluoride exposure and intake (birth to 10 years of age) from water, beverages, selected food products, dietary fluoride supplements, and fluoride toothpaste was collected using questionnaires sent to parents at 3- and 4- month intervals from birth to 48 months of age and every 6 months thereafter. Three trained and calibrated examiners used the Fluorosis Risk Index (FRI) categories to assess 16 late-erupting teeth among 465 study participants. A tooth was defined as having definitive fluorosis if any of the zones on that tooth had an FRI score of 2 or 3. Participants with questionable fluorosis were excluded from analyses. Descriptive and logistic regression analyses were performed to assess the importance of fluoride intake during different time periods. Results: Most dental fluorosis in the study population was mild, with only four subjects (1%) having severe fluorosis (FRI Score 3). The overall prevalence of dental fluorosis was 27.8%. Logistic regression analyses showed that fluoride intake from each of the individual years from age 2 to 8 plays an important role in determining the risk of dental fluorosis for most late-erupting permanent teeth. The strongest association for fluorosis on the late-erupting permanent teeth was with fluoride intake during the sixth year of life. Conclusion: Late-erupting teeth may be susceptible to fluorosis for an extended period from about age 2 to 8. Although not as visually prominent as the maxillary central incisors, some of the late-erupting teeth are esthetically important and this should be taken into consideration when making recommendations about dosing of fluoride intake

DOMINATION AND EXPLOITATION IN THE WORLD ECONOMY IN THE 1990s

Summary This speculative article explores the economic and ethical aspects of inequality in the new post?cold war world and the relations of domination required to reproduce them in the context of a more general theory of exploitation. Some of the factors affecting international inequality and economic power in the post?war period are described and analysed. These are examined from the perspective of income distribution; poverty; growth and convergence; natural resources; human resources and productive knowledge; institutions; accumulation, distribution and exploitation; markets; status exploitation and gender. The conclusion is that the new world order lacks both moral legitimacy and democratic institutions to govern the world economy. In this context, the evolving relations of domination and exploitation which reproduce the levels of inequality described may end up producing a new world disorder. Resumé Le dominance et l'exploitation dans l'économie mondiale au cours des années 1990 L'auteur explore spéculativement, dans le cadre d'une théorie plus générale de l'exploitation, les aspects économiques et moraux de l'inégalité dans le nouveau monde d'après la Guerre froide, ainsi que les rapports dominateurs impliqués dans la replication de cette inégalité. Certains des facteurs qui affectent l'inégalité internationale et le pouvoir économique dans la période d'après?guerre sont décrits et analysés dans l'article. Ces facteurs sont examinés due point de vue de la distribution des revenus; de la pauvreté; de la croissance et de la convergence; des ressources naturelles; des ressources humaines et des connaissances productives; des institutions; de l'accumulation, de la distribution et de l'exploitation; des marchés; de l'exploitation du statut et du genre. La conclusion est que sans légitimité morale, le libéralisme économique dépourvu de diversité institutionnelle ou d'institutions démocratiques capables de gouverner l'économie mondiale, l'évolution des relations de domination et d'exploitation qui reproduisent les niveaux d'inégalité décrits dans l'article pourraient, à la longue, produire un nouveau désordre d'envergure mondiale. Resumen Dominación y explotación en la economía mundial en la década del 90 Este artículo especulativo explora los aspectos económicos y éticos de la desigualdad mundial en la nueva etapa pos?guerra fría, y las relaciones de dominación requeridas para reproducirlos en el contexto de una teoría de explotación más general. Se describen y analizan algunos de los factores que afectan a la desigualdad internacional, y al poder económico en esta nueva era. Estos factores son examinados desde la perspectivas de distribución de ingresos; pobreza; crecimiento y convergencia; recursos nacionales; recursos humanos y conocimiento productivo; instituciones; acumulación, distribución y explotación; mercados; explotación de categoría y género. La conclusión es que, sin una legitimidad moral, un liberalismo económico sin diversidad institucional o instituciones democráticas a cargo de la economía mundial, las relaciones de dominación y explotación que reproducen los niveles de desigualdad descriptos podrían producir eventualmente un nuevo desorden mundial

Fully Endoscopic Microvascular Decompression for Trigeminal Neuralgia

Trigeminal neuralgia (TN) is a chronic, progressive facial pain disorder characterized by severe paroxysmal episodes in the distribution of the trigeminal nerve. The most common cause of (TN) is compression of the trigeminal nerve by a vascular structure within the posterior fossa at the dorsal root entry zone (DREZ). Initially described by Dr. Peter Janetta, microvascular decompression has been clearly demonstrated to be a safe and effective treatment for TN with excellent immediate and long-term pain relief.1 Although neuroimaging has advanced significantly allowing for improved pre-operative visualization of the trigeminal nerve and determination of vascular conflict, most neurosurgeons continue to practice the MVD procedure in a very similar manner to Dr. Janetta’s 1967 description.2 While the retrosigmoid craniotomy and operative microscope allows for an excellent view of the posterior aspect of the trigeminal nerve within the cerebellopontine angle, visualization of the anterior aspect of the nerve is limited. Additionally, adequate visualization of the DREZ may be difficult and require additional retraction of the cerebellum, potentially resulting in complications such as hearing loss and cerebellar injury. As neurosurgical experience with the endoscope has grown, a variety of authors have described performing microvascular decompression with endoscopic assistance which involves using the endoscope to inspect the trigeminal nerve for sites of compression but performing the decompression under the microscope. While the main advantage of the endoscopic approach compared to the microscopic approach is improved visualization of the trigeminal nerve from the DREZ to Meckel’s cave including its inferior, anterior and superior surfaces, evolution of the procedure to a fully endoscopic approach has the additional benefits of being less invasive with minimal soft tissue dissection and cerebellar retraction allowing for reduced patient discomfort and accelerated recovery. In this technical review, we describe our approach to performing a fully endoscopic microvascular decompression including the surgical nuances that allow the procedure to be performed safely and efficiently. Pages 2-