Fragmentation energy in rock avalanches

La fragmentation est un des mécanismes opérant lors d'avalanche rocheuses. La quantification de l'énergie associée à ce mécanisme permettrait d'apprécier l'influence de celui-ci sur la phase post-rupture d'une avalanche rocheuse. Dans cet article, les distributions des tailles des blocs du massif rocheux et des débris sont présentées et comparées pour neuf cas d'avalanches rocheuses : cinq dans les montagnes Rocheuses canadiennes et quatre dans les Alpes européennes. Des degrés de fragmentation ont pu être estimés. Pour évaluer l'énergie de fragmentation, deux méthodes on été examinées : l'une est basée sur l'énergie de concassage et l'autre est basée sur l'énergie de sautage utilisée dans le domaine minier. Les résultats obtenus portent à croire qu'il y aurait une relation entre l'indice de réduction de taille (Rr = D50/d50) et l'énergie potentielle par unité de volume, normalisée par la résistance au double poinçonnement (?HG/?c). Les énergies de fragmentation calculées pour les neuf cas étudiés donne en moyenne 20 % de l'énergie potentielle. Une relation empirique entre Rr et ?HG/?c est proposée, et est par la suite utilisée pour définir un indice de désintégration (ID). Cet indice reflète la physique du processus de désintégration puisqu'il considère que l'indice de réduction de taille est fonction de l'énergie dissipée et de la résistance de la roche. Ces facteurs connus depuis longtemps n'avaient jamais été présentés d'une façon cohérente pour des cas d'avalanches rocheuses.Mots clés : avalanches rocheuses, désintégration, énergie de fragmentation, Rocheuses canadiennes, Alpes européennes.

La comunicación del conocimiento científico en la Universidad de los niños EAFIT. Medellín – Colombia

Este proyecto de investigación se ubica en el tópico de la comunicación de la ciencia y la apropiación del conocimiento científico en las “Universidades de los niños”, programas que buscan acercar el quehacer investigativo de las instituciones de educación superior a niños (7 -12 años) y jóvenes (13 – 16 años).La investigación se realizará sobre un caso de estudio particular: la Universidad de los niños EAFIT de Medellín (Colombia), al ser el único programa registrado en Latinoamérica en la Red de Universidades de los niños Europea (EUCU.NET). El propósito en primer lugar, es analizar, bajo la descripción de las interacciones comunicativas que allí se instauran -entre los niños y jóvenes, los estudiantes universitarios que cumplen el papel de talleristas, y los profesores investigadores de la Universidad-, si se percibe una motivación para apropiarse del conocimiento científico, lo que significa tener un papel más activo y propositivo en el intercambio de saberes.Y en segundo lugar, analizar las percepciones de los participantes respecto a las diferencias entre la manera de abordar el conocimiento bajo la propuesta pedagógica y metodológica de los colegios y la planteada por la Universidad de los niños EAFIT.Al ser reciente la aparición de este fenómeno educativo y social de la Universidad de los niños en el continente europeo, es poca la literatura académica publicada. Por ello, tener un análisis del caso particular de Colombia, dará mayores variables sociales y culturales que podrán ser un insumo para la construcción de aristas teóricas sobre el mismo.Este trabajo final corresponde al Máster de Estudios Avanzados en Comunicación y está estructurado bajo la modalidad de proyecto investigativo para la elaboración de la tesis doctoral, que espera ser realizada en el programa de Doctorado en Comunicación Social de esta universidad.

Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008.

OBJECTIVE: To provide an update to the original Surviving Sepsis Campaign clinical management guidelines, "Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock," published in 2004. DESIGN: Modified Delphi method with a consensus conference of 55 international experts, several subsequent meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. This process was conducted independently of any industry funding. METHODS: We used the GRADE system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations. A strong recommendation indicates that an intervention's desirable effects clearly outweigh its undesirable effects (risk, burden, cost), or clearly do not. Weak recommendations indicate that the tradeoff between desirable and undesirable effects is less clear. The grade of strong or weak is considered of greater clinical importance than a difference in letter level of quality of evidence. In areas without complete agreement, a formal process of resolution was developed and applied. Recommendations are grouped into those directly targeting severe sepsis, recommendations targeting general care of the critically ill patient that are considered high priority in severe sepsis, and pediatric considerations. RESULTS: Key recommendations, listed by category, include: early goal-directed resuscitation of the septic patient during the first 6 hrs after recognition (1C); blood cultures prior to antibiotic therapy (1C); imaging studies performed promptly to confirm potential source of infection (1C); administration of broad-spectrum antibiotic therapy within 1 hr of diagnosis of septic shock (1B) and severe sepsis without septic shock (1D); reassessment of antibiotic therapy with microbiology and clinical data to narrow coverage, when appropriate (1C); a usual 7-10 days of antibiotic therapy guided by clinical response (1D); source control with attention to the balance of risks and benefits of the chosen method (1C); administration of either crystalloid or colloid fluid resuscitation (1B); fluid challenge to restore mean circulating filling pressure (1C); reduction in rate of fluid administration with rising filing pressures and no improvement in tissue perfusion (1D); vasopressor preference for norepinephrine or dopamine to maintain an initial target of mean arterial pressure > or = 65 mm Hg (1C); dobutamine inotropic therapy when cardiac output remains low despite fluid resuscitation and combined inotropic/vasopressor therapy (1C); stress-dose steroid therapy given only in septic shock after blood pressure is identified to be poorly responsive to fluid and vasopressor therapy (2C); recombinant activated protein C in patients with severe sepsis and clinical assessment of high risk for death (2B except 2C for post-operative patients). In the absence of tissue hypoperfusion, coronary artery disease, or acute hemorrhage, target a hemoglobin of 7-9 g/dL (1B); a low tidal volume (1B) and limitation of inspiratory plateau pressure strategy (1C) for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure in acute lung injury (1C); head of bed elevation in mechanically ventilated patients unless contraindicated (1B); avoiding routine use of pulmonary artery catheters in ALI/ARDS (1A); to decrease days of mechanical ventilation and ICU length of stay, a conservative fluid strategy for patients with established ALI/ARDS who are not in shock (1C); protocols for weaning and sedation/analgesia (1B); using either intermittent bolus sedation or continuous infusion sedation with daily interruptions or lightening (1B); avoidance of neuromuscular blockers, if at all possible (1B); institution of glycemic control (1B) targeting a blood glucose < 150 mg/dL after initial stabilization ( 2C ); equivalency of continuous veno-veno hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1A); use of stress ulcer prophylaxis to prevent upper GI bleeding using H2 blockers (1A) or proton pump inhibitors (1B); and consideration of limitation of support where appropriate (1D). Recommendations specific to pediatric severe sepsis include: greater use of physical examination therapeutic end points (2C); dopamine as the first drug of choice for hypotension (2C); steroids only in children with suspected or proven adrenal insufficiency (2C); a recommendation against the use of recombinant activated protein C in children (1B). CONCLUSION: There was strong agreement among a large cohort of international experts regarding many level 1 recommendations for the best current care of patients with severe sepsis. Evidenced-based recommendations regarding the acute management of sepsis and septic shock are the first step toward improved outcomes for this important group of critically ill patients.

Evaluation par des médecins installés de l'efficacité antihypertensive de la débrisoquine, de la méthyldopa et du propranolol [Evaluation by practicing physicians of the antihypertensive efficacy of debrisoquin, methyldopa and propranolol]

The antihypertensive effect of debrisoquine (20 mg/day), methyldopa (100 mg/day) and propranolol (160 mg/day) was compared to that obtained with a placebo in a controlled trial carried out by a group of 14 internists. Forty-eight patients with uncomplicated essential hypertension were included. Mefruside (25 mg/day) was first given alone for 6 weeks ("open phase" of the trial) and to this diuretic was then added in double-blind fashion and randomized sequence a placebo or an active drug. Each of the 4 blind phases lasted 4 weeks. At the end of the "open phase", blood pressure in seated position averaged 168/111 +/- 19.6/13.5 mm Hg (mean +/- SD). A significant blood pressure decrease was observed after 4 weeks of treatment with the placebo as well as with the investigated compounds. With the placebo blood pressure was reduced to 158/102 +/- 19.6/13.5 mm Hg (p less than 0.001). The magnitude of the additional blood pressure decrease induced by the active drugs was relatively small and varied from 4 (debrisoquine) to 10 mm Hg (methyldopa, p less than 0.01) for the systolic and from 3 (debrisoquine, p less than 0.05) to 5 mm Hg (propranolol, p less than 0.05) for the diastolic. The percentage of patients with systolic pressure of less than or equal to 140 mm Hg and with diastolic pressure of less than 90 mm Hg during administration of either drug was not greater than 40 to 20% respectively. Propranolol appeared to be better tolerated than the other antihypertensive agents. These rather disappointing blood pressure results suggest that the efficacy of antihypertensive agents in private practice cannot be extrapolated from studies carried out in specialized hypertension clinics.

Blood pressure normalization in a large population of hypertensive patients treated with perindopril/indapamide combination: results of the OPTIMAX trial.

OBJECTIVE: To determine if the fixed-dose perindopril/indapamide combination (Per/Ind) normalizes blood pressure (BP) in the same fraction of hypertensive patients when treated in everyday practice or in controlled trials. METHODS: In this prospective trial, 17 938 hypertensive patients were treated with Per 2 mg/Ind 0.625 mg for 3-6 months. In Group 1 Per/Ind was initiated in newly diagnosed patients (n = 7032); in Group 2 Per/Ind replaced previous therapy in patients already treated but having either their BP still uncontrolled or experiencing side-effects (n = 7423); in Group 3 Per/Ind was added to previous treatment in patients with persistently high BP (n = 3483). BP was considered normalized when &lt; or = 140/90 mm Hg. A multivariate analysis for predictors of BP normalization was performed. RESULTS: Subjects were on average 62 years old and had a baseline BP of 162.3/93.6 mm Hg. After treatment with Per/Ind, BP normalization was reached in 69.6% of patients in the Initiation group, 67.5% in the Replacement Group, and 67.4% in the Add-on Group (where patients were more frequently at risk, diabetic, or with target organ damage). Mean decreases in systolic BP of 22.8 mm Hg and in diastolic BP of 12.4 mm Hg were recorded. CONCLUSIONS: This trial was established to reflect everyday clinical practice, and a treatment strategy based on the Per/Ind combination, administered as initial, replacement, or add-on therapy, led to normalization rates that were superior to those observed in Europe in routine practice. These results support recent hypertension guidelines which encourage the use of combination therapy in the management of arterial hypertension.

Mukautumista vai realiteettien tunnustamista? : katsaus uusimpaan DDR:n kirkkohistorian tutkimukseen

Aulikki Mäkinen

Hemoglobin concentration and cerebral metabolism in patients with aneurysmal subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: The optimal hemoglobin (Hgb) target after aneurysmal subarachnoid hemorrhage is not precisely known. We sought to examine the threshold of Hgb concentration associated with an increased risk of cerebral metabolic dysfunction in patients with poor-grade subarachnoid hemorrhage. METHODS: Twenty consecutive patients with poor-grade subarachnoid hemorrhage who underwent multimodality neuromonitoring (intracranial pressure, brain tissue oxygen tension, cerebral microdialysis) were studied prospectively. Brain tissue oxygen tension and extracellular lactate/pyruvate ratio were used as markers of cerebral metabolic dysfunction and the relationship between Hgb concentrations and the incidence of brain hypoxia (defined by a brain tissue oxygen tension <20 mm Hg) and cell energy dysfunction (defined by a lactate/pyruvate ratio >40) was analyzed. RESULTS: Compared with higher Hgb concentrations, a Hgb concentration <9 g/dL was associated with lower brain tissue oxygen tension (27.2 [interquartile range, 21.2 to 33.1] versus 19.9 [interquartile range, 7.1 to 33.1] mm Hg, P=0.02), higher lactate/pyruvate ratio (29 [interquartile range, 25 to 38] versus 36 [interquartile range, 26 to 59], P=0.16), and an increased incidence of brain hypoxia (21% versus 52%, P<0.01) and cell energy dysfunction (23% versus 43%, P=0.03). On multivariable analysis, a Hgb concentration <9 g/dL was associated with a higher risk of brain hypoxia (OR, 7.92; 95% CI, 2.32 to 27.09; P<0.01) and cell energy dysfunction (OR, 4.24; 95% CI, 1.33 to 13.55; P=0.02) after adjusting for cerebral perfusion pressure, central venous pressure, PaO(2)/FIO(2) ratio, and symptomatic vasospasm. CONCLUSIONS: A Hgb concentration <9 g/dL is associated with an increased incidence of brain hypoxia and cell energy dysfunction in patients with poor-grade subarachnoid hemorrhage.

El Programa Presupuestal 0068 El Niño (EN), el IMARPE

El Programa Presupuestal 0068 (PP0068) financiado por el Ministerio de Economía y Finanzas (MEF), denominado: “REDUCCION DE VULNERABILIDAD Y ATENCION DE EMERGENCIAS POR DESASTRES”, donde el IMARPE conjuntamente con el SENAMHI, la DIRECCIÓN GENERAL DE HIDROGRAFÍA DE LA MARINA DE GUERRA DEL PERÚ y el INSTITUTO GEOFÍSICO DEL PERÚ, que conforman entre otros el Comité Multisectorial para el Estudio Nacional del Fenómeno El Niño (ENFEN), participan en este programa presupuestal con el producto “Entidades Informadas en forma permanente y con pronóstico frente al Fenómeno El Niño”, generado por las actividades de estas instituciones de acuerdo a su especialidad y que a través de Informes Técnicos mensuales son entregados de manera oportuna a las autoridades a nivel nacional y regional, así como a la comunidad en general

Validation of a clinical algorithm to identify low-risk patients with pulmonary embolism.

Summary Background: We previously derived a clinical prognostic algorithm to identify patients with pulmonary embolism (PE) who are at low-risk of short-term mortality who could be safely discharged early or treated entirely in an outpatient setting. Objectives: To externally validate the clinical prognostic algorithm in an independent patient sample. Methods: We validated the algorithm in 983 consecutive patients prospectively diagnosed with PE at an emergency department of a university hospital. Patients with none of the algorithm's 10 prognostic variables (age >/= 70 years, cancer, heart failure, chronic lung disease, chronic renal disease, cerebrovascular disease, pulse >/= 110/min., systolic blood pressure < 100 mm Hg, oxygen saturation < 90%, and altered mental status) at baseline were defined as low-risk. We compared 30-day overall mortality among low-risk patients based on the algorithm between the validation and the original derivation sample. We also assessed the rate of PE-related and bleeding-related mortality among low-risk patients. Results: Overall, the algorithm classified 16.3% of patients with PE as low-risk. Mortality at 30 days was 1.9% among low-risk patients and did not differ between the validation and the original derivation sample. Among low-risk patients, only 0.6% died from definite or possible PE, and 0% died from bleeding. Conclusions: This study validates an easy-to-use, clinical prognostic algorithm for PE that accurately identifies patients with PE who are at low-risk of short-term mortality. Low-risk patients based on our algorithm are potential candidates for less costly outpatient treatment.

Ovatko kielitieteilijät parhaita polittisen käsitteistön historioitsijoita

Kari Palonen

Gene-Age Interactions in Blood Pressure Regulation: A Large-Scale Investigation with the CHARGE, Global BPgen, and ICBP Consortia.

Although age-dependent effects on blood pressure (BP) have been reported, they have not been systematically investigated in large-scale genome-wide association studies (GWASs). We leveraged the infrastructure of three well-established consortia (CHARGE, GBPgen, and ICBP) and a nonstandard approach (age stratification and metaregression) to conduct a genome-wide search of common variants with age-dependent effects on systolic (SBP), diastolic (DBP), mean arterial (MAP), and pulse (PP) pressure. In a two-staged design using 99,241 individuals of European ancestry, we identified 20 genome-wide significant (p ≤ 5 × 10(-8)) loci by using joint tests of the SNP main effect and SNP-age interaction. Nine of the significant loci demonstrated nominal evidence of age-dependent effects on BP by tests of the interactions alone. Index SNPs in the EHBP1L1 (DBP and MAP), CASZ1 (SBP and MAP), and GOSR2 (PP) loci exhibited the largest age interactions, with opposite directions of effect in the young versus the old. The changes in the genetic effects over time were small but nonnegligible (up to 1.58 mm Hg over 60 years). The EHBP1L1 locus was discovered through gene-age interactions only in whites but had DBP main effects replicated (p = 8.3 × 10(-4)) in 8,682 Asians from Singapore, indicating potential interethnic heterogeneity. A secondary analysis revealed 22 loci with evidence of age-specific effects (e.g., only in 20 to 29-year-olds). Age can be used to select samples with larger genetic effect sizes and more homogenous phenotypes, which may increase statistical power. Age-dependent effects identified through novel statistical approaches can provide insight into the biology and temporal regulation underlying BP associations.

Effect of ganglion blockade with pentolinium on circulating neuropeptide Y levels in conscious rats.

The vasoconstrictor peptide, neuropeptide Y (NPY), is present in perivascular noradrenergic neurons of all mammals studied and may be important in the regulation of blood pressure. High plasma levels of NPY have been measured in the rat. To investigate partially the source and factors controlling the release of the circulating peptide, the effect of pentolinium tartrate administration has been studied in conscious rats. Pentolinium given as a bolus (5 mg/kg) followed by an infusion of a further 5 mg/kg/30 min produced a highly significant reduction in blood pressure of more than 40 mm Hg, when compared to either basal values or control animals treated with saline. Pentolinium treatment resulted in significantly lower plasma neuropeptide Y levels (31.0 +/- 6.7 fmol/ml) compared with those of control animals (78.6 +/- 8.2 fmol/ml). Circulating catecholamines were also significantly reduced in those animals receiving pentolinium. These results are compatible with circulating NPY arising from the sympathetic nervous system, with release being controlled by the mechanisms already established for catecholamines.

Alternativa agronômica para o biossólido produzido no Distrito Federal: I - efeito na produção de milho e na adição de metais pesados em Latossolo no cerrado

O crescimento urbano em Brasília aumentou o volume de esgoto doméstico coletado, gerando maior volume de biossólido - resíduo final do tratamento do esgoto - depositado nos pátios da Companhia de Água e Esgoto de Brasília (CAESB). Embora ainda haja carência de informações técnicas que possam garantir segurança ambiental, viabilidade econômica e satisfação social de seu uso, a maior parte do biossólido tem sido utilizada como condicionador de solos e fertilizante pelos agricultores nas áreas agrícolas vizinhas. Neste trabalho, o biossólido, que continha 90 dag kg-1 de água (10 dag kg-1 de matéria seca), foi aplicado a um Latossolo Vermelho distrófico, em doses únicas de 54, 108 e 216 t ha-1. Na menor dose e sem qualquer adição de outros fertilizantes, o material forneceu nutrientes para o milho por três anos, resultando em uma produtividade média de grãos de 4.700 kg ha-1. O modelo de ajuste aos dados, definido pela equação quadrática Y = 2349,3** + 41,579** X - 0,1097** X ², R² = 0,9824**, em que Y representa a produtividade de milho (kg ha-1) e X, a dose de biossólido úmido aplicado (t ha-1), estima que a aplicação de 189,51 t ha-1 produziria o rendimento máximo de milho. Usando-se o fósforo (P2O5) como referência, o biossólido foi mais eficiente do que a adubação mineral com superfosfato triplo, apresentando um valor fertilizante médio de 125 % nos três anos de cultivo. Na dose de 54 t ha-1, o biossólido da CAESB incorpora ao solo 240 kg de P2O5, 320 kg de N, 160 kg de Ca, 13 kg de K2O. As concentrações dos metais pesados (Cd, Pb e Hg) presentes no biossólido são muito inferiores aos limites críticos para aplicação do material, e a aplicação de 54 t ha-1 de biossólido úmido incorpora ao solo pequenas quantidades daqueles metais, indicando que a contaminação do solo por aqueles poluentes não constituirá problema, desde que o esgoto urbano não receba contaminação por resíduos industriais.

A pilot assessment of alpha-stat vs pH-stat arterial blood gas analysis after cardiac arrest.

PURPOSE: Resuscitated cardiac arrest (CA) patients typically receive therapeutic hypothermia, but arterial blood gases (ABGs) are often assessed after adjustment to 37°C (alpha-stat) instead of actual body temperature (pH-stat). We sought to compare alpha-stat and pH-stat assessment of Pao2 and Paco2 in such patients. MATERIALS AND METHODS: Using ABG data obtained during the first 24 hours of intensive care unit admission, we determined the impact of measured alpha vs calculated pH-stat on Pao2 and Paco2 on patient classification and outcomes for CA patients. RESULTS: We assessed 1013 ABGs from 120 CA patients with a median age of patients 66 years (interquartile range, 50-76). Median alpha-stat Pao2 changed from 122 (95-156) to 107 (82-143) mm Hg with pH-stat and median Paco2 from 39 (34-46) to 35 (30-41) mm Hg (both P < .001). Using the categories of hyperoxemia, normoxemia, and hypoxemia, pH-stat estimation of Pao2 reclassified approximately 20% of patients. Using the categories of hypercapnia, normocapnia, and hypocapnia, pH stat estimation of Paco2 reclassified approximately 40% of patients. The mortality of patients in different Pao2 and Paco2 categories was similar for pH-stat and alpha-stat. CONCLUSIONS: Using the pH-stat method, fewer resuscitated CA patients admitted to intensive care unit were classified as hyperoxemic or hypercapnic compared with alpha-stat. These findings suggest an impact of ABG assessment methodology on Pao2, Paco2, and patient classification but not on associated outcomes.

Short-term moderate hypocapnia augments detection of optimal cerebral perfusion pressure.

An autoregulation-oriented strategy has been proposed to guide neurocritical therapy toward the optimal cerebral perfusion pressure (CPPOPT). The influence of ventilation changes is, however, unclear. We sought to find out whether short-term moderate hypocapnia (HC) shifts the CPPOPT or affects its detection. Thirty patients with traumatic brain injury (TBI), who required sedation and mechanical ventilation, were studied during 20 min of normocapnia (5.1±0.4 kPa) and 30 min of moderate HC (4.4±3.0 kPa). Monitoring included bilateral transcranial Doppler of the middle cerebral arteries (MCA), invasive arterial blood pressure (ABP), and intracranial pressure (ICP). Mx -autoregulatory index provided a measure for the CPP responsiveness of MCA flow velocity. CPPOPT was assessed as the CPP at which autoregulation (Mx) was working with the maximal efficiency. During normocapnia, CPPOPT (left: 80.65±6.18; right: 79.11±5.84 mm Hg) was detectable in 12 of 30 patients. Moderate HC did not shift this CPPOPT but enabled its detection in another 17 patients (CPPOPT left: 83.94±14.82; right: 85.28±14.73 mm Hg). The detection of CPPOPT was achieved via significantly improved Mx-autoregulatory index and an increase of CPP mean. It appeared that short-term moderate HC augmented the detection of an optimum CPP, and may therefore usefully support CPP-guided therapy in patients with TBI.