An application of the self-potential (SP) method in archaeogeophysical prospection

Usage of the self-potential (SP) method on archaeological sites has been very limited and the phenomena that form the SP anomalies are not very well known. We believe that the vertical capillary water flows around stone walls that can be encountered frequently in archaeological sites, the porosity of the soil surrounding the archaeological structures, the moisture and clay ratio of the soil, and the changes in pH value of the soil, may form the SP anomalies. Moreover, an SP anomaly also may be formed if there is a moisture condition cutting the sulphuric and oxidized deposits under the earth. We determined, by our research, that the SP method can be very important, especially for determining the soil distribution and for archaeological research. The study was carried out on an Assyrian Tread Colony Period artificial hill in Acemhöyük, the chemical and physical structure of which was changed significantly after a large fire in approximately 1789±50 bc. The structure boundaries were found by interpreting the anomalies obtained from analytical modelling techniques, and an analysis of the SP mechanism of the area was attempted. In addition, the noise on the anomalies was eliminated by signal analysis techniques, thus enabling us to interpret the results more precisely. © 1996 John Wiley and Sons, Ltd

A dynamic analysis of why learners develop a preference for autonomous learners in computer-mediated communication

A large number of studies in CMC have assessed how social interaction, processes and learning outcomes are intertwined. The present research explores how the degree of self-determination of learners, that is the motivational orientation of a learner, influences the communication and interaction patterns in an online Problem Based Learning environment. Given the complexity of CMC, we expected that autonomous learners would be more willing to contribute to cognitive discourse. In time, we expected that control-oriented learners would develop a preferential attachment to contribute to discourse from autonomous learners. Data were gathered from 37 autonomous and 39 control-oriented learners who posted 1669 messages. Using a dynamic multi-method approach of content analysis of cognitive and social discourse, social network analysis, and measures of academic motivation, we find some preliminary evidence that motivational orientation influences communication and social interaction patterns amongst learners. From the beginning, most control-oriented learners develop a preference to connect to and communicate with autonomous learners, although a separate team-analysis indicates that group dynamics also influence how learners develop connections with other learners in time. Our findings further the understanding of differences found in distance learning courses about participation and drop-out

Recurrent recessive mutation in deoxyguanosine kinase causes idiopathic noncirrhotic portal hypertension

Despite advances in the diagnosis and management of idiopathic noncirrhotic portal hypertension, its pathogenesis remains elusive. Insight may be gained from study of early-onset familial idiopathic noncirrhotic portal hypertension, in which Mendelian mutations may account for disease. We performed exome sequencing of eight subjects from six kindreds with onset of portal hypertension of indeterminate etiology during infancy or childhood. Three subjects from two consanguineous families shared the identical rare homozygous p.N46S mutation in DGUOK, a deoxyguanosine kinase required for mitochondrial DNA replication; haplotype sharing demonstrated that the mutation in the two families was inherited from a remote common ancestor. All three affected subjects had stable portal hypertension with noncirrhotic liver disease for 6-16 years of follow-up. This mutation impairs adenosine triphosphate binding and reduces catalytic activity. Loss-of-function mutations in DGUOK have previously been implicated in cirrhosis and liver failure but not in isolated portal hypertension. Interestingly, treatment of patients with human immunodeficiency viral infection with the nucleoside analogue didanosine is known to cause portal hypertension in a subset of patients and lowers deoxyguanosine kinase levels in vitro; the current findings implicate these effects on deoxyguanosine kinase in the causal mechanism

Immunocompromised patients with acute respiratory distress syndrome : Secondary analysis of the LUNG SAFE database

The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p < 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p < 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013

Mechanical ventilation in patients with cardiogenic pulmonary edema : a sub-analysis of the LUNG SAFE study

Patients with acute respiratory failure caused by cardiogenic pulmonary edema (CPE) may require mechanical ventilation that can cause further lung damage. Our aim was to determine the impact of ventilatory settings on CPE mortality. Patients from the LUNG SAFE cohort, a multicenter prospective cohort study of patients undergoing mechanical ventilation, were studied. Relationships between ventilatory parameters and outcomes (ICU discharge/hospital mortality) were assessed using latent mixture analysis and a marginal structural model. From 4499 patients, 391 meeting CPE criteria (median age 70 [interquartile range 59-78], 40% female) were included. ICU and hospital mortality were 34% and 40%, respectively. ICU survivors were younger (67 [57-77] vs 74 [64-80] years, p < 0.001) and had lower driving (12 [8-16] vs 15 [11-17] cmHO, p < 0.001), plateau (20 [15-23] vs 22 [19-26] cmHO, p < 0.001) and peak (21 [17-27] vs 26 [20-32] cmHO, p < 0.001) pressures. Latent mixture analysis of patients receiving invasive mechanical ventilation on ICU day 1 revealed a subgroup ventilated with high pressures with lower probability of being discharged alive from the ICU (hazard ratio [HR] 0.79 [95% confidence interval 0.60-1.05], p = 0.103) and increased hospital mortality (HR 1.65 [1.16-2.36], p = 0.005). In a marginal structural model, driving pressures in the first week (HR 1.12 [1.06-1.18], p < 0.001) and tidal volume after day 7 (HR 0.69 [0.52-0.93], p = 0.015) were related to survival. Higher airway pressures in invasively ventilated patients with CPE are related to mortality. These patients may be exposed to an increased risk of ventilator-induced lung injury. Trial registration Clinicaltrials.gov NCT02010073