689 research outputs found
Secondary organic aerosol yields from the oxidation of benzyl alcohol
Recent inventory-based analysis suggests that emissions of volatile chemical products in urban areas are competitive with those from the transportation sector. Understanding the potential for secondary organic aerosol formation from these volatile chemical products is therefore critical to predicting levels of aerosol and for formulating policy to reduce aerosol exposure. Experimental and computationally simulated environmental chamber data provide an understanding of aerosol yield and chemistry under relevant urban conditions (5ā200āppb NO and 291ā312āK) and give insight into the effect of volatile chemical products on the production of secondary organic aerosol. Benzyl alcohol, one of these volatile chemical products, is found to have a large secondary organic aerosol formation potential. At NO concentrations of ā¼ā80āppb and 291āK, secondary organic aerosol mass yields for benzyl alcohol can reach 1
Goal-directed mechanisms that constrain retrieval predict subsequent memory for new "foil" information.
To remember a previous event, it is often helpful to use goal-directed control processes to constrain what comes to mind during retrieval. Behavioral studies have demonstrated that incidental learning of new "foil" words in a recognition test is superior if the participant is trying to remember studied items that were semantically encoded compared to items that were non-semantically encoded. Here, we applied subsequent memory analysis to fMRI data to understand the neural mechanisms underlying the "foil effect". Participants encoded information during deep semantic and shallow non-semantic tasks and were tested in a subsequent blocked memory task to examine how orienting retrieval towards different types of information influences the incidental encoding of new words presented as foils during the memory test phase. To assess memory for foils, participants performed a further surprise old/new recognition test involving foil words that were encountered during the previous memory test blocks as well as completely new words. Subsequent memory effects, distinguishing successful versus unsuccessful incidental encoding of foils, were observed in regions that included the left inferior frontal gyrus and posterior parietal cortex. The left inferior frontal gyrus exhibited disproportionately larger subsequent memory effects for semantic than non-semantic foils, and significant overlap in activity during semantic, but not non-semantic, initial encoding and foil encoding. The results suggest that orienting retrieval towards different types of foils involves re-implementing the neurocognitive processes that were involved during initial encoding.James S. McDonnell Foundation (Scholar Award), Medical Research Council, Wellcome TrustThis is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuropsychologia.2016.07.01
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Inhibition of apoptotic Bax translocation to the mitochondria is a central function of parkin
Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder, affecting 1ā3% of the population over 65. Mutations in the ubiquitin E3 ligase parkin are the most common cause of autosomal recessive PD. The parkin protein possesses potent cell-protective properties and has been mechanistically linked to both the regulation of apoptosis and the turnover of damaged mitochondria. Here, we explored these two functions of parkin and the relative scale of these processes in various cell types. While biochemical analyses and subcellular fractionation were sufficient to observe robust parkin-dependent mitophagy in immortalized cells, higher resolution techniques appear to be required for primary culture systems. These approaches, however, did affirm a critical role for parkin in the regulation of apoptosis in primary cultured neurons and all other cells studied. Our prior work demonstrated that parkin-dependent ubiquitination of endogenous Bax inhibits its mitochondrial translocation and can account for the anti-apoptotic effects of parkin. Having found a central role for parkin in the regulation of apoptosis, we further investigated the parkin-Bax interaction. We observed that the BH3 domain of Bax is critical for its recognition by parkin, and identified two lysines that are crucial for parkin-dependent regulation of Bax translocation. Last, a disease-linked mutation in parkin failed to influence Bax translocation to mitochondria after apoptotic stress. Taken together, our data suggest that regulation of apoptosis by the inhibition of Bax translocation is a prevalent physiological function of parkin regardless of the kind of cell stress, preventing overt cell death and supporting cell viability during mitochondrial injury and repair
Pathological study of elective nephrectomies for a two year period
Background: Nephrectomies whether partial, total or radical are common surgical procedures these days with trauma being the most common cause of an emergency nephrectomy. The indications of elective nephrectomies vary with different age groups- malignancies being common in the elderly age group and non-neoplastic indications of nephrectomy may present in any age group. The present study was undertaken in view of the increasing elective nephrectomies in our area thus analyzing the common causes requiring nephrectomy as a treatment. The present study also aimed at determining the age and sex distribution of various renal lesions requiring a nephrectomy.Methods: It was a prospective study for a period of 2 years - January 2013 to December 2014. A total of 45 nephrectomies were included in the study. Detailed clinical, biochemical and imaging findings were taken into consideration before analyzing each case. Results: There was a male predominance(64.4%) and 26.6% of the cases were in the age group of 40-50 years. 95.5% of the nephrectomies were performed for a non-neoplastic indication. Involvement of the right and left kidney was almost equal in the study. Chronic pyelonephritis was the most common histopathological diagnosis(68.8%).Conclusion: Inflammatory causes more commonly required a nephrectomy in the study population.Ā Chronic calculous pyelonephritis was the most common underlying pathophysiology leading to a nonfunctioning kidney thus highlighting the early treatment of renal calculi.
Alpha Oscillations during Incidental Encoding Predict Subsequent Memory for New "Foil" Information.
People can employ adaptive strategies to increase the likelihood that previously encoded information will be successfully retrieved. One such strategy is to constrain retrieval toward relevant information by reimplementing the neurocognitive processes that were engaged during encoding. Using EEG, we examined the temporal dynamics with which constraining retrieval toward semantic versus nonsemantic information affects the processing of new "foil" information encountered during a memory test. Time-frequency analysis of EEG data acquired during an initial study phase revealed that semantic compared with nonsemantic processing was associated with alpha decreases in a left frontal electrode cluster from around 600 msec after stimulus onset. Successful encoding of semantic versus nonsemantic foils during a subsequent memory test was related to decreases in alpha oscillatory activity in the same left frontal electrode cluster, which emerged relatively late in the trial at around 1000-1600 msec after stimulus onset. Across participants, left frontal alpha power elicited by semantic processing during the study phase correlated significantly with left frontal alpha power associated with semantic foil encoding during the memory test. Furthermore, larger left frontal alpha power decreases elicited by semantic foil encoding during the memory test predicted better subsequent semantic foil recognition in an additional surprise foil memory test, although this effect did not reach significance. These findings indicate that constraining retrieval toward semantic information involves reimplementing semantic encoding operations that are mediated by alpha oscillations and that such reimplementation occurs at a late stage of memory retrieval, perhaps reflecting additional monitoring processes
UK construction companiesā strategies in the face of business cycles
Firms in the construction industry have always had to deal with the challenges of the economic cycle and develop strategies to deal with the resulting fluctuations in their business environment. In the context of the 2008ā2011 double-dip recession in the UK, the results of a survey targeting the top one hundred construction companies in the UK are reported here. This research is particularly intended to assess whether the strategies of large companies in the construction sector, when faced with the issues associated with the variation in the economic cycle, have changed since the previous business cycle (i.e. the 1986ā1990 boom followed by the 1990ā1991 recession). The survey reveals the challenges that companies have faced, reports on company behaviour and on the policies adopted. While there are many similarities between policies adopted during the recessionary periods of the two cycles, the research found notable changes in attitudes towards diversification, human resource management and price bidding
Characterization of aerosol hygroscopicity over the Northeast Pacific Ocean: Impacts on prediction of CCN and stratocumulus cloud droplet number concentrations
During the Marine Aerosol Cloud and Wildfire Study (MACAWS) in June and July of 2018, aerosol composition and cloud condensation nuclei (CCN) properties were measured over the N.E. Pacific to characterize the influence of aerosol hygroscopicity on predictions of ambient CCN and stratocumulus cloud droplet number concentrations (CDNC). Three vertical regions were characterized, corresponding to the marine boundary layer (MBL), an aboveācloud organic aerosol layer (ACāOAL), and the free troposphere (FT) above the ACāOAL. The aerosol hygroscopicity parameter (Īŗ) was calculated from CCN measurements (Īŗ_(CCN)) and bulk aerosol mass spectrometer (AMS) measurements (Īŗ_(AMS)). Within the MBL, measured hygroscopicities varied between values typical of both continental environments (~0.2) and remote marine locations (~0.7). For most flights, CCN closure was achieved within 20% in the MBL. For five of the seven flights, assuming a constant aerosol size distribution produced similar or better CCN closure than assuming a constant āmarineā hygroscopicity (Īŗ = 0.72). An aerosolācloud parcel model was used to characterize the sensitivity of predicted stratocumulus CDNC to aerosol hygroscopicity, size distribution properties, and updraft velocity. Average CDNC sensitivity to accumulation mode aerosol hygroscopicity is 39% as large as the sensitivity to the geometric median diameter in this environment. Simulations suggest CDNC sensitivity to hygroscopicity is largest in marine stratocumulus with low updraft velocities (0.6 m sā»Ā¹), where hygroscopic properties of the Aitken mode dominate hygroscopicity sensitivity
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