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Cruising with a Crystal Ball: Estimating Timber Density with a Wedge Prism
Foresters use a wedge shaped prism to estimate timber density in a stand in a process called variable plot sampling. Featuring Dr. John Bell
Brain enhancement through cognitive training: A new insight from brain connectome
Owing to the recent advances in neurotechnology and the progress in understanding of brain cognitive functions, improvements of cognitive performance or acceleration of learning process with brain enhancement systems is not out of our reach anymore, on the contrary, it is a tangible target of contemporary research. Although a variety of approaches have been proposed, we will mainly focus on cognitive training interventions, in which learners repeatedly perform cognitive tasks to improve their cognitive abilities. In this review article, we propose that the learning process during the cognitive training can be facilitated by an assistive system monitoring cognitive workloads using electroencephalography (EEG) biomarkers, and the brain connectome approach can provide additional valuable biomarkers for facilitating leaners' learning processes. For the purpose, we will introduce studies on the cognitive training interventions, EEG biomarkers for cognitive workload, and human brain connectome. As cognitive overload and mental fatigue would reduce or even eliminate gains of cognitive training interventions, a real-time monitoring of cognitive workload can facilitate the learning process by flexibly adjusting difficulty levels of the training task. Moreover, cognitive training interventions should have effects on brain sub-networks, not on a single brain region, and graph theoretical network metrics quantifying topological architecture of the brain network can differentiate with respect to individual cognitive states as well as to different individuals' cognitive abilities, suggesting that the connectome is a valuable approach for tracking the learning progress. Although only a few studies have exploited the connectome approach for studying alterations of the brain network induced by cognitive training interventions so far, we believe that it would be a useful technique for capturing improvements of cognitive function
Insights on geochemical cycling of U, Re and Mo from seasonal sampling in Boston Harbor, Massachusetts, USA
Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 71 (2007): 895-917, doi:10.1016/j.gca.2006.10.016.This study examined the removal of U, Mo, and Re from seawater by
sedimentary processes at a shallow-water site with near-saturation bottom water O2 levels
(240-380 μmol O2/L), very high organic matter oxidation rates (annually averaged rate is
870 μmol C/cm2/y), and shallow oxygen penetration depths (4 mm or less throughout the
year). Under these conditions, U, Mo, and Re were removed rapidly to asymptotic pore
water concentrations of 2.2–3.3 nmol/kg (U), 7–13 nmol/kg (Mo), and 11–14 pmol/kg
(Re). The order in which the three metals were removed, determined by fitting a
diffusion-reaction model to measured profiles, was Re < U < Mo. Model fits also suggest
that the Mo profiles clearly showed the presence of a near-interface layer in which Mo
was added to pore waters by remineralization of a solid phase. The importance of this
solid phase source of pore water Mo increased from January to October as the organic
matter oxidation rate increased, bottom water O2 decreased, and the O2 penetration depth
decreased. Experiments with in situ benthic flux chambers generally showed fluxes of U
and Mo into the sediments. However, when the overlying water O2 concentration in the
chambers was allowed to drop to very low levels, Mn and Fe were released to the
overlying water along with the simultaneous release of Mo and U. These experiments
suggest that remineralization of Mn and/or Fe oxides may be a source of Mo and perhaps
U to pore waters, and may complicate the accumulation of U and Mo in bioturbated
sediments with high organic matter oxidation rates and shallow O2 penetration depths.
Benthic chamber experiments including the nonreactive solute tracer, Br-,
indicated that sediment irrigation was very important to solute exchange at the study site.
The enhancement of sediment-seawater exchange due to irrigation was determined for
the nonreactive tracer (Br-), TCO2, NH4
+, U and Mo. The comparisons between these
solutes showed that reactions within and around the burrows were very important for
modulating the Mo flux, but less important for U. The effect of these reactions on Mo
exchange was highly variable, enhancing Mo (and, to a lesser extent, U) uptake at times
of relatively modest irrigation, but inhibiting exchange when irrigation rates were faster.
These results reinforce the observation that Mo can be released to and removed from pore
waters via sedimentary reactions.
The removal rate of U and Mo from seawater by sedimentary reactions was found
to agree with the rate of accumulation of authigenic U and Mo in the solid phase. The
fluxes of U and Mo determined by in situ benthic flux chamber measurements were the
largest that have been measured to date. These results confirm that removal of redoxsensitive
metals from continental margin sediments underlying oxic bottom water is
important, and suggest that continental margin sediments play a key role in the marine
budgets of these metals.We appreciate the financial support
from the National Science Foundation (OCE-0220892). Funding for this work was also
provided to JLM by the Postdoctoral Scholar Program at WHOI courtesy of the Cabot
Marine Environmental Science Fund and the J. Seward Johnson Fund. Financial support
to IMK was given by The Swedish Foundation for International Cooperation in Research
and Higher Education
Mountain strongholds for woody angiosperms during the Late Pleistocene in SE Iberia
Mediterranean mountains played an essential role during glacial periods as vegetation refugia. The SE Iberia Late Pleistocene woody angiosperm fossil and floristic evidences are reviewed in the context of phylogeographical studies aiming to identify (i) spatial patterns related to woody angiosperms glacial survival, (ii) structural and functional characteristics of montane refugia, and (iii) gaps in knowledge on the woody angiosperm patterns of survival in Mediterranean mountains. The distribution of palaeobotanical data for SE Iberia refugia has been found to be taphonomically biased due to the scarcity of available and/or studied high-altitude Late Pleistocene sites. However, Siles Lake data together with floristic inference provide evidences for woody angiosperms’ survival in a high-altitude Mediterranean area. The main features boosting survival at montane contexts are physiographic complexity and water availability. Phylogeography studies have mainly been conducted at a continental scale. Although they cohere with palaeobotanical data to a broad scale, a general lack of sampling of SE Iberian range-edge populations, as well as misconceptions about the origin of the populations sampled, impede to infer the proper location of woody angiosperms’ mountain refugia and their importance in the post-glacial European colonisation. We conclude that floristic, geobotanical, palaeobotanical, ethnographical and genetic evidence should be merged to gain a deeper understanding on the role played by Mediterranean mountains as glacial refugia in order to explain the current distribution of many plants and the large biodiversity levels encountered in Mediterranean mountain areas. This is hallmark for effective and efficient conservation and management
Metastatização linfática oculta no carcinoma epidermóide das vias aerodigestivas superiores
Regulating electricity and natural gas in Peru : solutions for a sustainable energy sector
Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2014.Cataloged from PDF version of thesis.Includes bibliographical references (pages 57-59).Peru is one of the fastest growing countries in Latin America, thanks in part to industry fueled by generous endowments of hydro power capacity and natural gas reserves. However, investment in electricity generation capacity has not kept pace with the rapid increase in demand and threatens to stymie future economic growth. A flawed regulatory environment is to blame, and specific roadblocks to increased generation investments include a dysfunctional capacity payment system, low administratively determined gas prices, and structural barriers to investment in hydro. This thesis provides an overview of the design, functioning and historical context for energy regulation in Peru; identifies the key barriers to generation investment; analyzes two potential regulatory reforms; and recommends the specific reform that has the most promise for reigniting investment in hydro. Two reforms strike at the root of the current problem: The first, increasing the price of natural gas for power generators up to the economic netback value of LNG exports, would make hydro a viable investment but would hit consumers with very large increases in their electricity bills. An alternative approach, a reform to the capacity payment mechanism, could provide the same benefits in terms of drawing new generator investment but at a much lower cost to consumers. It would also offer benefits for regulatory discretion in the future evolution of the grid.by Alex Cade Breckel.S.M. in Technology and Polic
Letter, To: "Very Rev. T. C. Middleton, D.D., O.S.A." From: George J. Breckel, May 21, 1904.
Letter, To: "Very Rev. T. C. Middleton, D.D., O.S.A." From: George J. Breckel, May 23, 1904.
Ubiquitin Ligase Redundancy and Nuclear-Cytoplasmic Localization in Yeast Protein Quality Control
The diverse functions of proteins depend on their proper three-dimensional folding and assembly. Misfolded cellular proteins can potentially harm cells by forming aggregates in their resident compartments that can interfere with vital cellular processes or sequester important factors. Protein quality control (PQC) pathways are responsible for the repair or destruction of these abnormal proteins. Most commonly, the ubiquitin-proteasome system (UPS) is employed to recognize and degrade those proteins that cannot be refolded by molecular chaperones. Misfolded substrates are ubiquitylated by a subset of ubiquitin ligases (also called E3s) that operate in different cellular compartments. Recent research in Saccharomyces cerevisiae has shown that the most prominent ligases mediating cytoplasmic and nuclear PQC have overlapping yet distinct substrate specificities. Many substrates have been characterized that can be targeted by more than one ubiquitin ligase depending on their localization, and cytoplasmic PQC substrates can be directed to the nucleus for ubiquitylation and degradation. Here, we review some of the major yeast PQC ubiquitin ligases operating in the nucleus and cytoplasm, as well as current evidence indicating how these ligases can often function redundantly toward substrates in these compartments
Yeast 26S proteasome nuclear import is coupled to nucleus-specific degradation of the karyopherin adaptor protein Sts1
Abstract In eukaryotes, the ubiquitin–proteasome system is an essential pathway for protein degradation and cellular homeostasis. 26S proteasomes concentrate in the nucleus of budding yeast Saccharomyces cerevisiae due to the essential import adaptor protein Sts1 and the karyopherin-α protein Srp1. Here, we show that Sts1 facilitates proteasome nuclear import by recruiting proteasomes to the karyopherin-α/β heterodimer. Following nuclear transport, the karyopherin proteins are likely separated from Sts1 through interaction with RanGTP in the nucleus. RanGTP-induced release of Sts1 from the karyopherin proteins initiates Sts1 proteasomal degradation in vitro. Sts1 undergoes karyopherin-mediated nuclear import in the absence of proteasome interaction, but Sts1 degradation in vivo is only observed when proteasomes successfully localize to the nucleus. Sts1 appears to function as a proteasome import factor during exponential growth only, as it is not found in proteasome storage granules (PSGs) during prolonged glucose starvation, nor does it appear to contribute to the rapid nuclear reimport of proteasomes following glucose refeeding and PSG dissipation. We propose that Sts1 acts as a single-turnover proteasome nuclear import factor by recruiting karyopherins for transport and undergoing subsequent RanGTP-initiated ubiquitin-independent proteasomal degradation in the nucleus
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