3,185 research outputs found
On the foundations of cancer modelling: selected topics, speculations, & perspectives
This paper presents a critical review of selected topics related to the modelling of cancer onset, evolution and growth, with the aim of illustrating, to a wide applied mathematical readership, some of the novel mathematical problems in the field. This review attempts to capture, from the appropriate literature, the main issues involved in the modelling of phenomena related to cancer dynamics at all scales which characterise this highly complex system: from the molecular scale up to that of tissue. The last part of the paper discusses the challenge of developing a mathematical biological theory of tumour onset and evolution
Totem and Taboo: Fluids in sepsis
The need for early, rapid, and substantial fluid resuscitation in septic patients has long been an article of faith in the intensive care community, a tribal totem that is taboo to question. The results of a recent multicenter trial in septic children in Africa, published in The New England Journal of Medicine, powerfully challenge the fluid paradigm. The salient aspects of the trial need to be understood and reflected upon. In this commentary, we discuss the background to and findings of the trial and explain why they will likely trigger a re-evaluation of our thinking about fluids in sepsis, a re-evaluation that is already happening in the treatment of acute respiratory distress syndrome and acute kidney injury and in postoperative care
A geochemical traverse along the âSperchios Basin e Evoikos Gulfâ graben (Central Greece): Origin and evolution of the emitted fluids
The studied area is a 130 km long fast spreading graben in Central Greece. Its complex geodynamical setting includes both the presence of a subduction slab at depth responsible for the recent (Quaternary) volcanic activity in the area and the western termination of a tectonic lineament of regional importance (the North-Anatolian fault). A high geothermal gradient is made evident by the presence of many thermal springs with temperatures from 19 to 82 C, that discharge along the normal faults bordering the graben.
In the period 2004e2012, 58 gas and 69 water samples were collected and their chemical and isotopic analysis revealed a wide range of compositions.
Two main groups of thermal waters can be distinguished on the basis of their chemical composition. The first, represented by dilute waters (E.C. <0.6 mS/cm) of the westernmost sites, is characterised by the presence of CH4-rich and mixed N2eCH4 gases. The second displays higher salinities (E.C. from 12 to 56 mS/cm) due to mixing with a modified marine component. Reservoir temperatures of 150e160 C were estimated with cationic geothermometers at the easternmost sites.
Along the graben, from west to east, the gas composition changes from CH4- to CO2-dominated through mixed N2eCH4 and N2eCO2 compositions, while at the same time the He isotopic composi- tion goes from typical crustal values (<0.1 R/RA) up to 0.87 R/RA, showing in the easternmost sites a small (3e11%) but significant mantle input. The d13C values of the CO2-rich samples suggest a mixed origin (mantle and marine carbonates)
Energy Dissipation Burst on the Traffic Congestion
We introduce an energy dissipation model for traffic flow based on the
optimal velocity model (OV model). In this model, vehicles are defined as
moving under the rule of the OV model, and energy dissipation rate is defined
as the product of the velocity of a vehicle and resistant force which works to
it.Comment: 15 pages, 19 Postscript figures. Reason for replacing: This is the
submitted for
The fluidsâ geochemistry along the "Sperchios Basin - Northern Evoikos Gulf" Graben, a geodynamically complex area of Central Greece
The study area is a 130 km long fast spreading graben in Central Greece. Its complex geodynamical setting includes
both the presence at depth of a subduction slab responsible for the recent (Quaternary) volcanic activity in
the area and the western termination of a tectonic lineament of regional importance (the North-Anatolian fault). Its
high geothermal gradient is evidenced by the presence of many thermal springs with temperatures from 19 to 82
C, issuing along the normal faults bordering the graben.
In the period 2004-2012 about 50 gas and water samples have been collected and their chemical and isotopic analysis
revealed a wide range of compositions.
Going from west to east the gas composition changes from CH4- to CO2-dominated passing through mixed N2-
CH4 and N2-CO2 compositions, while at the same time the He isotopic composition goes from typical crustal
values (0.05 R/Ra) up to 0.87 R/Ra (corrected for air contamination), showing in the easternmost sites a small but
significant mantle input. Isotopic composition of CH4-C indicates a thermogenic origin for the CH4-rich samples
and hydrothermal origin for the remaining samples. Positive 15N values indicate a contribution of crustal derived
nitrogen for the N2-rich samples. The 13C values of most the CO2-enriched samples show a mixed origin (mantle
and marine carbonates).
Also the chemical composition of the waters shows differences along the graben and two main groups can be separated.
The first, represented by dilute waters (E.C. < 600 S/cm), is found in the westernmost sites characterised
by the presence of CH4-rich and mixed N2-CH4 gases. The remaining waters display higher salinities (E.C. from
12 to 56 mS/cm) due to the mixing with a modified marine component. Only the water composition of easternmost
sites in the Giggenbachâs cation triangular graph plots in the field of the partially equilibrated waters giving
estimated temperatures at depth of 150-160 C.PublishedVienna, Austria4.5. Studi sul degassamento naturale e sui gas petroliferiope
Simulating the role of subtropical stratocumulus clouds in driving Pacific climate variability
Spinor techniques for massive fermions with arbitrary polarization
We present a new variant of the spinor techniques for calculating the
amplitudes of processes involving massive fermions with arbitrary polarization.
It is relatively simple and leads to basic spinor products. Our procedure is
not more complex than CALCUL spinor techniques for massless fermions. We obtain
spinor Chisholm identities for massive fermions. As an illustration,
expressions are given for the amplitudes of electron-positron annihilation into
fermions-pairs for several polarizations.Comment: 14 pages, 2 figure
Introduction of Medical Emergency Teams in Australia and New Zealand: a multi-centre study
INTRODUCTION: Information about Medical Emergency Teams (METs) in Australia and New Zealand (ANZ) is limited to local studies and a cluster randomised controlled trial (the Medical Emergency Response and Intervention Trial [MERIT]). Thus, we sought to describe the timing of the introduction of METs into ANZ hospitals relative to relevant publications and to assess changes in the incidence and rate of intensive care unit (ICU) admissions due to a ward cardiac arrest (CA) and ICU readmissions. METHODS: We used the Australian and New Zealand Intensive Care Society database to obtain the study data. We related MET introduction to publications about adverse events and MET services. We compared the incidence and rate of readmissions and admitted CAs from wards before and after the introduction of an MET. Finally, we identified hospitals without an MET system which had contributed to the database for at least two years from 2002 to 2005 and measured the incidence of adverse events from the first year of contribution to the second. RESULTS: The MET status was known for 131 of the 172 (76.2%) hospitals that did not participate in the MERIT study. Among these hospitals, 110 (64.1%) had introduced an MET service by 2005. In the 79 hospitals in which the MET commencement date was known, 75% had introduced an MET by May 2002. Of the 110 hospitals in which an MET service was introduced, 24 (21.8%) contributed continuous data in the year before and after the known commencement date. In these hospitals, the mean incidence of CAs admitted to the ICU from the wards changed from 6.33 per year before to 5.04 per year in the year after the MET service began (difference of 1.29 per year, 95% confidence interval [CI] -0.09 to 2.67; P = 0.0244). The incidence of ICU readmissions and the mortality for both ICU-admitted CAs from wards and ICU readmissions did not change. Data were available to calculate the change in ICU admissions due to ward CAs for 16 of 62 (25.8%) hospitals without an MET system. In these hospitals, admissions to the ICU after a ward CA decreased from 5.0 per year in the first year of data contribution to 4.2 per year in the following year (difference of 0.8 per year, 95% CI -0.81 to 3.49; P = 0.3). CONCLUSION: Approximately 60% of hospitals in ANZ with an ICU report having an MET service. Most introduced the MET service early and in association with literature related to adverse events. Although available in only a quarter of hospitals, temporal trends suggest an overall decrease in the incidence of ward CAs admitted to the ICU in MET as well as non-MET hospitals
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