Rock deformation vs. radon emission: some constraints from shear stress-controlled experiments.

Numerous field and laboratory studies have been conducted to investigate the relationship between radon variation and seismic events, as well as the complex link between radon emission and rock deformation mechanisms. However, a clear understanding of this correspondence and systematic observations of these phenomena are still lacking, and recent experimental studies have yet to yield conclusive results. In this study, we investigate the possible relationships between radon migration dynamics and rock deformation at the micro-scale through laboratory experiments using the SHIVA apparatus under shear stress-controlled conditions and simultaneous high-resolution radon measurements.

A neural network based approach to classify VLF signals as rock rupture precursors.

The advent of novel technologies revealed that other geophysical signals than those directly related to fault motion could be used to probe the state of deformation of the Earth's crust. Electromagnetic signals belonging to this category have been increasingly investigated in the last decade in association to natural earthquakes and laboratory rock fractures. These studies are hampered by the lack of continuous recordings and a systematic mathematical processing of large data sets.

Decoding family-level features for modern and fossil leaves from computer-vision heat maps.

Premise: Angiosperm leaves present a classic identification problem due to their morphological complexity. Computer-vision algorithms can identify diagnostic regions in images, and heat map outputs illustrate those regions for identification, providing novel insights through visual feedback. We investigate the potential of analyzing leaf heat maps to reveal novel, human-friendly botanical information with applications for extant- and fossil-leaf identification.

Frictional Melting in Hydrothermal Fluid-Rich Faults: Field and Experimental Evidence From the Bolfín Fault Zone (Chile).

Tectonic pseudotachylytes are thought to be unique to certain water-deficient seismogenic environments and their presence is considered to be rare in the geological record. Here, we present field and experimental evidence that frictional melting can occur in hydrothermal fluid-rich faults hosted in the continental crust. Pseudotachylytes were found in the >40 km-long Bolfín Fault Zone of the Atacama Fault System, within two ca.

Fast and Localized Temperature Measurements During Simulated Earthquakes in Carbonate Rocks.

The understanding of earthquake physics is hindered by the poor knowledge of fault strength and temperature evolution during seismic slip. Experiments reproducing seismic velocity (∼1 m/s) allow us to measure both the evolution of fault strength and the associated temperature increase due to frictional heating. However, temperature measurements were performed with techniques having insufficient spatial and temporal resolution.

Fluid pressurisation and earthquake propagation in the Hikurangi subduction zone.

In subduction zones, seismic slip at shallow crustal depths can lead to the generation of tsunamis. Large slip displacements during tsunamogenic earthquakes are attributed to the low coseismic shear strength of the fluid-saturated and non-lithified clay-rich fault rocks. However, because of experimental challenges in confining these materials, the physical processes responsible for the coseismic reduction in fault shear strength are poorly understood.

Subseismic to Seismic Slip in Smectite Clay Nanofoliation.

Smectite clays are the main constituent of slipping zones found in subduction zone faults at shallow depth (e.g., <1-km depth in the Japan Trench) and in the decollements of large landslides (e.

Mechanical behaviour of fluid-lubricated faults.

Fluids are pervasive in fault zones cutting the Earth's crust; however, the effect of fluid viscosity on fault mechanics is mainly conjectured by theoretical models. We present friction experiments performed on both dry and fluid-permeated silicate and carbonate bearing-rocks, at normal effective stresses up to 20 MPa, with a slip-rate ranging between 10 μm/s and 1 m/s. Four different fluid viscosities were tested.

Adverse Event with the Use of Carmustine Wafers and Postoperative Radiochemotherapy for the Treatment of High-grade Glioma.

Randomized, controlled trials have shown significant improvement of survival after implantation of 1,3-bis(2-Chloroethyl)-1-nitrosourea (BCNU) wafers for patients suffering from high-grade glioma. A combination of local chemotherapy with BCNU and concomitant radiochemotherapy with temozolomide (TMZ) appears to be attractive to enhance the overall survival, even though these treatments may potentially cumulate their toxicity. We report a clinical case of a patient submitted to this combined treatment protocol.

Frictional Instabilities and Carbonation of Basalts Triggered by Injection of Pressurized HO- and CO- Rich Fluids.

The safe application of geological carbon storage depends also on the seismic hazard associated with fluid injection. In this regard, we performed friction experiments using a rotary shear apparatus on precut basalts with variable degree of hydrothermal alteration by injecting distilled HO, pure CO, and HO + CO fluid mixtures under temperature, fluid pressure, and stress conditions relevant for large-scale subsurface CO storage reservoirs. In all experiments, seismic slip was preceded by short-lived slip bursts.

Ultra-thin clay layers facilitate seismic slip in carbonate faults.

Many earthquakes propagate up to the Earth's surface producing surface ruptures. Seismic slip propagation is facilitated by along-fault low dynamic frictional resistance, which is controlled by a number of physico-chemical lubrication mechanisms. In particular, rotary shear experiments conducted at seismic slip rates (1 ms) show that phyllosilicates can facilitate co-seismic slip along faults during earthquakes.

G: Fracture energy, friction and dissipation in earthquakes.

Recent estimates of fracture energy in earthquakes show a power-law dependence with slip which can be summarized as ∝ where is a positive real slightly larger than one. For cracks with sliding friction, fracture energy can be equated to : the post-failure integral of the dynamic weakening curve. If the dominant dissipative process in earthquakes is friction, and should be comparable and show a similar scaling with slip.

An empirically based steady state friction law and implications for fault stability.

Empirically based rate-and-state friction laws (RSFLs) have been proposed to model the dependence of friction forces with slip and time. The relevance of the RSFL for earthquake mechanics is that few constitutive parameters define critical conditions for fault stability (i.e.

Fast-moving dislocations trigger flash weakening in carbonate-bearing faults during earthquakes.

Rupture fronts can cause fault displacement, reaching speeds up to several ms(-1) within a few milliseconds, at any distance away from the earthquake nucleation area. In the case of silicate-bearing rocks the abrupt slip acceleration results in melting at asperity contacts causing a large reduction in fault frictional strength (i.e.

[Diverse histological lesions in a patient with antiphospholipid syndrome (APS)].

Antiphospholipid syndrome (APS) is a rare autoimmune disorder. It can be secondary to systemic lupus erythematosus (SLE) or occur in the absence of autoimmune disease. The hallmark of this so-called primary APS is the presence of circulating antiphospholipid antibodies.

[Recomendation for the management of the brain arteriovenous malformations].

Intracranial arteriovenous malformations constitute an heterogeneous group of lesions that represent a real challenge to the neurosurgeon. Their variability in size, topography, angioarchitecture, angioarchitecture, etc., and also the multiple clinical presentations, lead to varied therapeutic approaches.

[Aneurysms of the distal anterior cerebral artery].

The clinical, angiographic and surgical features of 13 (out of 18) patients harboring pericallosal aneurysms and operated on by the same group of neurosurgeons, are analyzed. The mortality rate of the whole series was 5.5% with good (GOS II) or excellent (GOS I) recovery in the 91.

[Variants of the anterior circle of Willis. Anatomic and angiografic correlation and its implications in the surgery of intracranial aneurysms. (Acigos anterior cerebral artery, median artery of the corpus callosum and accessory middle cerebral artery)].

It is worlwide accepted that in almost 60% of cases, anatomical variants in the Circle of Willis can be found. Some of them are associated with vascular malformations such as aneurysms. The knowledge of these anatomical variants is of vital importance when facing surgery, being the aims to preserve arteries in unusual localisations, which when injured can determine invalidating sequelae.

[Descompresive craniectomy in head injury. Intractable I.C.P. ].

Decompressive craniotomy is a neurosurical technique known since the origin of neurosurgery, but its use as a routine started at the end of the 19th century. In last decades, the use of decompressive craniotomy decreased, mainly because of poor results obtained and the advances in medical treatment of refractory intracranial hypertension in the Intensive Care Units. Nevertheless, in recent years there has been a renewed interest with the use of this surgical techique in young patients with head injuries and severe intracranial hypertensio'n, but no surgical mass lesion, as well as in patients with ischemic stroke causing life threatening mass effect.

Surgical treatment of intracranial hypertension in encephalic cryptococcosis.

The incidence of cryptococcosis has risen sharply together with the growing number of patients with Acquired Immunodeficiency Syndrome (AIDS). Cryptococcal meningitis is nowadays the most common intracranial non-viral infection in such cases. One of its most serious complications is intracranial hypertension (ICH), a situation that can lead either to early death, or disabling sequelae.

[Recurrent meningiomas with progressive aggressiveness and posterior extracranial extension].

Meningiomas are in most cases benign tumors. They represent about 15% of primitive intracranial tumors. Complete surgical resection achieves healing in the majority of patients.

[Widespread endemic goiter and iodine deficiency in the province of Avellino].

1352 schoolchildren between 6-14 years old (699 males and 653 females) and 943 adults (176 males and 767 females) from eight villages of the province of Avellino were studied. All subjects were examined for thyroid size by at least two expert examiners. In most of them urine samples were collected for iodine determinations.

Infratentorial subdural empyema: clinical and computerized tomography findings. Report of three cases.

Infratentorial subdural empyemas are rare. The authors report three cases encountered between 1979 and 1988, representing a 3% incidence among all subdural empyemas. The common source was an ear infection.

Hyperthyroidism and Addison's disease in a patient with myotonic dystrophy.

A 53-year-old man had myotonic dystrophy, hyperthyroidism, and Addison's disease, an association not previously reported, to our knowledge. In the literature, at least five cases of hyperthyroidism associated with myotonic dystrophy have been described, but none also had Addison's disease. The presence of thyroid anti-microsomal antibodies and anti-adrenal antibodies suggests that the two endocrine disorders may be autoimmune.