Stratospheric Ozone Depletion Polvani, Lorenzo M.; Waugh, Darryn W.; Correa, Gustavo J. P. ...
Journal of climate,
02/2011, Letnik:
24, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The importance of stratospheric ozone depletion on the atmospheric circulation of the troposphere is studied with an atmospheric general circulation model, the Community Atmospheric Model, version 3 ...(CAM3), for the second half of the twentieth century. In particular, the relative importance of ozone depletion is contrasted with that of increased greenhouse gases and accompanying sea surface temperature changes. By specifying ozone and greenhouse gas forcings independently, and performing long, time-slice integrations, it is shown that the impacts of ozone depletion are roughly 2–3 times larger than those associated with increased greenhouse gases, for the Southern Hemisphere tropospheric summer circulation. The formation of the ozone hole is shown to affect not only the polar tropopause and the latitudinal position of the midlatitude jet; it extends to the entire hemisphere, resulting in a broadening of the Hadley cell and a poleward extension of the subtropical dry zones. The CAM3 results are compared to and found to be in excellent agreement with those of the multimodel means of the recent Coupled Model Intercomparison Project (CMIP3) and Chemistry–Climate Model Validation (CCMVal2) simulations. This study, therefore, strongly suggests that most Southern Hemisphere tropospheric circulation changes, in austral summer over the second half of the twentieth century, have been caused by polar stratospheric ozone depletion.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Surface roughness, porosity and contact angles of different carbon paper materials (TORAY paper with PTFE from 0% to 60% of and SGL paper with 0% and 20% of PTFE) suitable as electrodes in microbial ...fuel cells were investigated. The changes of contact angle between dry and clean anode surfaces and the ones after exposure to wastewater were measured using different liquids (pure water and sodium acetate solutions). The results showed that bacterial attachment to the carbon papers caused a significant decrease in the contact angle, shifting the surface property from highly hydrophobic to slightly hydrophobic or even hydrophilic. The quantity of biofilm attached on the anode surface decreased with the increase in PTFE content. Positive correlation between dry biomass content and the amount of pores at the small scale (5–10μm) was observed. The start up time of MFCs was shortened by using the carbon anodes without PTFE or with low PTFE content (<20wt%), probably due to the easier biofilm attachment on the surface. On the contrary, the carbon anodes with high PTFE contents had longer start up time. After several cycles of MFC operation, the performances became similar (20–30mV of differences) regardless of the carbon anode used.
This paper presents a single-phase cascaded H-bridge converter for a grid-connected photovoltaic (PV) application. The multilevel topology consists of several H-bridge cells connected in series, each ...one connected to a string of PV modules. The adopted control scheme permits the independent control of each dc-link voltage, enabling, in this way, the tracking of the maximum power point for each string of PV panels. Additionally, low-ripple sinusoidal-current waveforms are generated with almost unity power factor. The topology offers other advantages such as the operation at lower switching frequency or lower current ripple compared to standard two-level topologies. Simulation and experimental results are presented for different operating conditions.
On a hemispheric scale, it is now well established that stratospheric ozone depletion has been the principal driver of externally forced atmospheric circulation changes south of the Equator in the ...last decades of the 20th Century. The impact of ozone depletion has been felt over the entire hemisphere, as reflected in the poleward drift of the midlatitude jet, the southward expansion of the summertime Hadley cell and accompanying precipitation trends deep into the subtropics. On a regional scale, however, surface impacts directly attributable to ozone depletion have yet to be identified. In this paper we focus on South Eastern South America (SESA), a region that has exhibited one of the largest wetting trends during the 20th Century. We study the impact of ozone depletion on SESA precipitation using output from 6 different climate models, spanning a wide range of complexity. In all cases we contrast pairs of model integrations with and without ozone depletion, but with all other forcings identically specified. This allows for unambiguous attribution of the computed precipitation trends. All 6 climate models consistently reveal that stratospheric ozone depletion results in a significant wetting of SESA over the period 1960–1999. Taken as a whole, these model results strongly suggest that the impact of ozone depletion on SESA precipitation has been as large as, and quite possibly larger than, the one caused by increasing greenhouse gases over the same period.
Purpose
The purpose of this project was to evaluate research in basic oral care interventions to update evidence-based practice guidelines for preventing and treating oral mucositis (OM) in cancer ...patients undergoing radio- or chemotherapy.
Methods
A systematic review of available literature was conducted by the Basic Oral Care Section of the Mucositis Study Group of MASCC/ISOO. Seven interventions—oral care protocols, dental care, normal saline, sodium bicarbonate, mixed medication mouthwash, chlorhexidine, and calcium phosphate—were evaluated using the Hadorn (J Clin Epidemiol 49:749–754, 1996) criteria to determine level of evidence, followed by a guideline determination of one of the following: recommendation, suggestion, or no guideline possible, using Somerfield’s (Classic Pap Cur Comments 4:881–886, 2000) schema.
Results
Fifty-two published papers were examined by treatment population (radiotherapy, chemotherapy, and hematopoietic stem cell transplant) and by whether the intervention aimed to prevent or treat OM. The resulting practice suggestions included using oral care protocols for preventing OM across all treatment modalities and age groups and not using chlorhexidine mouthwash for preventing OM in adults with head and neck cancer undergoing radiotherapy. Considering inadequate and/or conflicting evidence, no guidelines for prevention or treatment of OM were possible for the interventions of dental care, normal saline, sodium bicarbonate, mixed medication mouthwash, chlorhexidine in patients receiving chemotherapy or hematopoietic stem cell transplant, or calcium phosphate.
Conclusions
The evidence for basic oral care interventions supports the use of oral care protocols in patient populations receiving radiation and/or chemotherapy and does not support chlorhexidine for prevention of mucositis in head and neck cancer patients receiving radiotherapy. Additional well-designed research is needed for other interventions to improve the amount and quality of evidence guiding future clinical care.
Gastric cancer is a major health burden worldwide and prevention is the most promising strategy to control the disease. The available scientific evidence indicates that curing Helicobacter pylori ...infection results in a modest retardation of the precancerous process but does not prevent all cancers. Individuals at the highest risk should be cured of their infection and monitored endoscopically to detect dysplasia and “early” cancer, amenable to successful treatment.
Severe bottlenecks significantly diminish the amount of genetic diversity and the speed at which it accumulates (i.e., evolutionary rate). They further compromise the efficiency of natural selection ...to eliminate deleterious variants, which may reach fixation in the surviving populations. Consequently, expanding and adapting to new environments may pose a significant challenge when strong bottlenecks result in genetic pauperization. Herein, we surveyed the patterns of nucleotide diversity, molecular adaptation and genetic load across 177 gene‐loci in a circum‐Mediterranean conifer (Pinus pinea L.) that represents one of the most extreme cases of genetic pauperization in widespread outbreeding taxa. We found very little genetic variation in both hypervariable nuclear microsatellites (SSRs) and gene‐loci, which translated into genetic diversity estimates one order of magnitude lower than those previously reported for pines. Such values were consistent with a strong population decline that began some ~1 Ma. Comparisons with the related and parapatric maritime pine (Pinus pinaster Ait.) revealed reduced rates of adaptive evolution (α and ωa) and a significant accumulation of genetic load. It is unlikely that these are the result from differences in mutation rate or linkage disequilibrium between the two species; instead they are the presumable outcome of contrasting demographic histories affecting both the speed at which these taxa accumulate genetic diversity, and the global efficacy of selection. Future studies, and programs for conservation and management, should thus start testing for the effects of genetic load on fitness, and integrating such effects into predictive models.
Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a death ligand cytokine known for its cytotoxic activity against malignantly transformed cells. TRAIL induces cell death through ...binding to death receptors DR4 and DR5. The inhibitory decoy receptors (DcR1 and DcR2) co-expressed with death receptor 4 (DR4)/DR5 on the same cell can block the transmission of the apoptotic signal. Here, we show that DcRs also regulate TRAIL sensitivity at a supracellular level and thus represent a mechanism by which the microenvironment can diminish tumour TRAIL sensitivity. Mathematical modelling and layered or spheroid stroma-extracellular matrix-tumour cultures were used to model the tumour microenvironment. By engineering TRAIL to escape binding by DcRs, we found that DcRs do not only act in a cell-autonomous or cis-regulatory manner, but also exert trans-cellular regulation originating from stromal cells and affect tumour cells, highlighting the potent inhibitory effect of DcRs in the tumour tissue and the necessity of selective targeting of the two death-inducing TRAIL receptors to maximise efficacy.
Purpose
To update the 2013 Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO) clinical practice guidelines on oral cryotherapy for the ...management of oral mucositis (OM) caused by cancer therapies.
Methods
A systematic review was conducted by the Mucositis Study Group of MASCC/ISOO. The evidence for each intervention for specific cancer treatment modalities was assigned a level of evidence (LoE). The findings were added to the database used to develop the 2013 MASCC/ISOO clinical practice guidelines. Based on the LoE, the guidelines were set as: recommendation, suggestion, or no guideline possible.
Results
A total of 114 papers were identified: 44 from PubMed and 70 from Web of Science. After abstract triage and merging with the 2013 database, 36 papers were reviewed. The LoE for prevention of OM with oral cryotherapy in patients undergoing autologous hematopoietic stem cell transplant using high-dose melphalan conditioning protocols was upgraded, and the guideline changed to
recommendation
. Additionally, the recommendation for prevention of OM with oral cryotherapy in patients receiving bolus 5-fluorouracil for the treatment of solid tumors was confirmed. No guidelines were possible for other clinical settings.
Conclusions
The evidence supports recommendations for the use of oral cryotherapy for the prevention of OM for either (i) patients undergoing autologous hematopoietic stem cell transplant with high-dose melphalan conditioning protocols or (ii) patients receiving bolus 5-fluorouracil chemotherapy.
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