Temperature-driven micro-fracturing in granite: The interplay between microstructure, mineralogy and tensile strength.

High temperatures exert a significant influence on the mechanical and fluid flow properties of rocks and minerals. In crystalline rocks, differential thermal expansion of minerals is known to induce microfracture damage leading to changes in bulk volume and tensile strength. Here we report new data from thermally treated core samples of Devon Granite in order to constrain the interplay between tensile strength and thermally-induced damage with respect to the background mineralogy. A series of core samples was cyclically heated at temperatures ranging from 25 to 800 °C, with P-wave velocity and porosity measured after each cycle. Tensile strength decreased significantly from 9 MPa to less than 3 MPa as thermal treatment increased from 25 to 800 °C. The mechanical data were then compared to fracture density values obtained by optical maps of microfracture damage to assess the quantity and degree of linkage of intergranular and intragranular fractures using the FraqPaQ toolbox. The fracture density increased from 0.02 m m - 2 to 2.0 m m - 2 which is consistent with results obtained from direct physical parameters as calculated from elastic wave data. We conclude that the combined effects of thermal expansion and the α - ß phase transition within quartz crystals has a pronounced effect on tensile strength.

Microscopic Evolution of Laboratory Volcanic Hybrid Earthquakes.

Characterizing the interaction between fluids and microscopic defects is one of the long-standing challenges in understanding a broad range of cracking processes, in part because they are so difficult to study experimentally. We address this issue by reexamining records of emitted acoustic phonon events during rock mechanics experiments under wet and dry conditions. The frequency spectrum of these events provides direct information regarding the state of the system. Such events are typically subdivided into high frequency (HF) and low frequency (LF) events, whereas intermediate "Hybrid" events, have HF onsets followed by LF ringing. At a larger scale in volcanic terranes, hybrid events are used empirically to predict eruptions, but their ambiguous physical origin limits their diagnostic use. By studying acoustic phonon emissions from individual microcracking events we show that the onset of a secondary instability-related to the transition from HF to LF-occurs during the fast equilibration phase of the system, leading to sudden increase of fluid pressure in the process zone. As a result of this squeezing process, a secondary instability akin to the LF event occurs. This mechanism is consistent with observations of hybrid earthquakes.

Observation of the Kibble-Zurek Mechanism in Microscopic Acoustic Crackling Noises.

Characterizing the fast evolution of microstructural defects is key to understanding "crackling" phenomena during the deformation of solid materials. For example, it has been proposed using atomistic simulations of crack propagation in elastic materials that the formation of a nonlinear hyperelastic or plastic zone around moving crack tips controls crack velocity. To date, progress in understanding the physics of this critical zone has been limited due to the lack of data describing the complex physical processes that operate near microscopic crack tips. We show, by analyzing many acoustic emission events during rock deformation experiments, that the signature of this nonlinear zone maps directly to crackling noises. In particular, we characterize a weakening zone that forms near the moving crack tips using functional networks, and we determine the scaling law between the formation of damages (defects) and the traversal rate across the critical point of transition. Moreover, we show that the correlation length near the transition remains effectively frozen. This is the main underlying hypothesis behind the Kibble-Zurek mechanism (KZM) and the obtained power-law scaling verifies the main prediction of KZM.

Deep dermal granuloma annulare presenting as an eyelid tumor in a child, with review of pediatric eyelid lesions.

A case of deep dermal granuloma annulare (GA) involving the eyelid of a child is reported. GA presenting in the periocular region is rare and may mimic other lesions. The differential diagnosis of pediatric eyelid lesions is reviewed.

Acute generalized exanthematous pustulosis induced by chromium picolinate.

A case of acute generalized exanthematous pustulosis (AGEP) due to chromium picolinate is described. This supplemental form of chromium has received a great deal of interest recently because of its possible beneficial effects on both muscle strength and body composition. There have been no previous reports to our knowledge of adverse cutaneous reactions to this agent. Various aspects of AGEP are reviewed.

The United States military and leishmaniasis.

Leishmaniasis occurs not only in American travelers and military personnel alike but infects a significant portion of the world's population. The US military has made major contributions to the understanding of the complicated epidemiology of this parasite, the development of rapid reliable diagnostic tests, and to the development of safe, more efficient, and more effective treatment of leishmaniasis.

Safety and efficacy of intravenous sodium stibogluconate in the treatment of leishmaniasis: recent U.S. military experience.

The efficacy and toxicity of sodium stibogluconate (SSG) at a dosage of 20 mg/(kg.d) for either 20 days (for cutaneous disease) or 28 days (for visceral, mucosal, or viscerotropic disease) in the treatment of leishmaniasis is reported. Ninety-six U.S. Department of Defense health care beneficiaries with parasitologically confirmed leishmaniasis were prospectively followed for 1 year. One patient was infected with human immunodeficiency virus; otherwise, comorbidity was absent. Clinical cure occurred in 91% of 83 cases of cutaneous disease and 93% of 13 cases of visceral/viscerotropic disease. Adverse effects were common and necessitated interruption of treatment in 28% of cases, but they were generally reversible. These included arthralgias and myalgias (58%), pancreatitis (97%), transaminitis (67%), headache (22%), hematologic suppression (44%), and rash (9%). No subsequent mucosal leishmaniasis was identified, and there were no deaths attributable to SSG or leishmaniasis.

Felodipine-induced gingival hyperplasia.

Felodipine is a calcium channel blocking agent used in the management of hypertension and angina. We report a case of gingival hyperplasia in a patient with chronic use of this drug. Gingival changes occurred soon after initiation of felodipine and improved upon its discontinuation. The clinical characteristics, inciting agents, proposed pathogenetic mechanisms, as well as prevention and treatment of drug-induced gingival hyperplasia are briefly reviewed.

Acinic cell carcinoma presenting as an upper lip mass.

BACKGROUND: Acinic cell carcinoma (ACC) is a rare tumor generally involving the parotid gland and infrequently the minor salivary glands. OBJECTIVE: Clinical and histopathological characteristics of a case of ACC of the minor salivary glands, and brief review of the literature. METHODS: Routine stains with H&E, PAS, iron, and mucicarmine; immunohistochemistry with cytokeratin, CEA, S-100, and leu-M1. RESULTS: The ACC was removed by wide local excision. Histopathology revealed papillary cystic, solid, and ductal architectural features. The mucinous material within the lumina of the cystic and ductal structures was PAS and mucicarmine positive, and diastase resistant. All tested immunohistochemical reagents reacted with the epithelial cells. There were no mitoses, necrosis, cellular pleomorphism, or infiltration. CONCLUSIONS: ACC is a rare tumor of salivary glands characterized by an indolent clinical course with the potential for both local recurrence and metastatic spread when tracked for decades. Published mortality rates vary from 6 to 50%. Histopathologic features do not reliably predict biologic behavior.

Cutaneous angiosarcoma arising in the radiation site of a congenital hemangioma.

We describe a patient in whom angiosarcoma developed at the site of a hemangioma that was treated during infancy with radiation for refractory thrombocytopenia. Our findings, along with those of the 10 reported cases from the world literature, are summarized. One third of angiosarcomas arise in the skin. They most often show one of three clinical patterns. First and most common is occurrence as a bruiselike lesion on the scalp or face of an elderly person. Second in frequency is the Stewart-Treves syndrome. Third and least common is angiosarcoma developing as a sequela of previous radiation therapy. The prognosis in general is poor, with a mean survival length of 24 months and a 5-year survival rate of 10%. Effective treatment relies on early diagnosis and wide-margin surgical excision.

Essential syphilitic alopecia revisited.

There has been a resurgence of syphilis in the past decade. Uncommonly, diffuse hair loss, termed essential alopecia, is the only sign of syphilitic infection. We describe two patients with syphilis in whom the first sign of disease was alopecia and discuss the clinical and histopathologic findings of essential syphilitic alopecia.

Phialophora verrucosa: a new cause of mycetoma.

A 29-year-old Thai woman had draining sinus tracts, tumefaction, and granules on the plantar aspect of the foot. Phialophora verrucosa was isolated from the lesion. P. verrucosa is a major agent of chromoblastomycosis, which is known to rarely cause subcutaneous phaeohyphomycosis. This dematiaceous fungus has not been previously reported to cause mycetoma. This case illustrates the clinical spectrum of disease of this fungus. The salient features of mycetoma and management options are presented.

A dose-ranging study of the efficacy and safety of azelastine nasal spray in the treatment of seasonal allergic rhinitis with an acute model.

BACKGROUND: Oral azelastine, a nonsteroidal antiinflammatory respiratory investigational drug has demonstrated activity in the treatment of allergic rhinitis and asthma with a good safety profile. METHODS: Azelastine nasal spray was compared with sustained-release oral chlorpheniramine maleate and placebo for efficacy and safety in the treatment of seasonal allergic rhinitis in a double-dummy, two-center, 2-day, double-blind, randomized, dose-ranging, parallel-groups, onset and duration of action study. Two hundred sixty-four subjects reported to an outdoor park on Saturday morning during the height of the fall pollen season and remained there for 8 hours that day and the next to ensure maximal exposure to seasonal aeroallergens. Symptom diary cards were collected hourly Saturday from 8:00 AM to 10:00 AM (baseline period). Subjects who had sufficient symptoms were randomized into five groups and received medication at 10:00 AM and 10:00 PM on Saturday and at 10:00 AM on Sunday: azelastine 0.1% (1 spray [0.12 mg] per nostril every 12 hours, 2 sprays per nostril every every 12 hours, or 2 sprays per nostril once daily), Chlor-Trimeton Repetabs (12 mg twice daily), or placebo (twice daily). Diary cards were completed hourly (11:00 AM to 4:00 PM) and at 6:00, 8:00, and 10:00 PM on Saturday and again hourly on Sunday (from 8:00 AM to 4:00 PM) to evaluate rhinitis symptoms and adverse events. RESULTS: Two hundred fifty-nine subjects completed the study. The groups that received 2 sprays of azelastine per nostril once and twice daily and the chlorpheniramine group had statistically significantly more improvement in total rhinitis symptoms than the placebo group without serious adverse events. CONCLUSIONS: This study supports a once to twice daily dosing regimen for 2 sprays of 0.1% azelastine in the acute treatment of allergic rhinitis with onset of action within 2 to 3 hours.