1,798 research outputs found

    PUBLIC CONSERVATION LAND AND EMPLOYMENT GROWTH IN THE NORTHERN FOREST REGION

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    As with many environmental issues, debates about increasing public conservation lands in the Northern Forest region frequently center on a perceived tradeoff between jobs and the environment. In particular, opponents of conservation lands often argue that employment will decline significantly when land is diverted from commodity-oriented uses such as wood products production. To evaluate this claim, we estimate a model of simultaneous employment and net migration growth using data on the 92 non-metropolitan counties comprising the region. Growth in employment and net migration are measured over the period 1990 to 1997 and the set of exogenous variables includes the 1990 share of the county land base in public conservation uses. We find that net migration rates were systematically higher in counties with more conservation lands, but the effects are relatively small. Public conservation lands were found to have no systematic effect on employment growth over the 1990 to 1997 period. Two extensions are considered. We examine the separate effects of preservationist and multiple-use lands. We also identify a "natural experiment" involving changes in national forest management that allows us to estimate the effects of diverting private forestland to public conservation uses. Our central conclusions are that existing public conservation lands have a positive, but small, effect on employment and migration in the Northern Forest region and that, over the range of our data, employment and migration are unlikely to be affected by timber harvest reductions resulting from the establishment of new conservation lands.Labor and Human Capital, Land Economics/Use,

    Local Employment Growth, Migration, and Public Land Policy: Evidence from the Northwest Forest Plan

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    Debates over protecting public land reveal two views. Some argue protection reduces commodity production, reducing local employment and increasing out-migration. Others contend protection produces amenities that support job growth and attract migrants. We test these competing views for the Northwest Forest Plan (NWFP), which reallocated 11 million acres of federal land from timber production to protecting old-growth forest species. We find evidence that land protection directly reduced local employment growth and increased net migration. The total negative effect on employment was offset only slightly by positive migration-driven effects. Employment losses were concentrated in metropolitan counties, but percentage losses were higher in rural counties.amenities, employment growth, migration, Northwest Forest Plan, oldgrowth forests, public land management, Community/Rural/Urban Development, Land Economics/Use,

    SAMBA: Superconducting antenna-coupled, multi-frequency, bolometric array

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    We present a design for a multipixel, multiband (100 GHz, 200 GHz and 400 GHz) submillimeter instrument: SAMBA (Superconducting Antenna-coupled, Multi-frequency, Bolometric Array). SAMBA uses slot antenna coupled bolometers and microstrip filters. The concept allows for a much more compact, multiband imager compared to a comparable feedhorn-coupled bolometric system. SAMBA incorporates an array of slot antennas, superconducting transmission lines, a wide band multiplexer and superconducting transition edge bolometers. The transition-edge film measures the millimeter-wave power deposited in the resistor that terminates the transmission line

    Opportunities for Bio-Based Solvents Created as Petrochemical and Fuel Products Transition towards Renewable Resources

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    The global bio-based chemical market is growing in size and importance. Bio-based solvents such as glycerol and 2-methyltetrahydrofuran are often discussed as important introductions to the conventional repertoire of solvents. However adoption of new innovations by industry is typically slow. Therefore it might be anticipated that neoteric solvent systems (e.g., ionic liquids) will remain niche, while renewable routes to historically established solvents will continue to grow in importance. This review discusses bio-based solvents from the perspective of their production, identifying suitable feedstocks, platform molecules, and relevant product streams for the sustainable manufacturing of conventional solvents

    Acid-catalysed carboxymethylation, methylation and dehydration of alcohols and phenols with dimethyl carbonate under mild conditions

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    Dimethyl carbonate (DMC) chemistry has been extended to include acid-catalysed reactions of different aliphatic alcohols and phenols. For the first time, p-toluenesulfonic acid (PTSA), H2SO4, AlCl3 and FeCl3 have been shown to aid carboxymethylation for primary aliphatic alcohols at catalytic loadings with quantitative conversion and selectivity. For carboxymethylation of secondary alcohols, stoichiometric PTSA and catalytic AlCl3 both gave quantitative conversion and selectivity. Stoichiometric FeCl3 and H2SO4 promoted dehydration of linear aliphatic alcohols. Additionally FeCl3 catalysed methylation of cyclohexanol, whilst AlCl3 resulted in methylation of phenolic compounds. This research expands the range of potential application for DMC in green chemistry

    A comparison of the solvation power of the green solvent 2,2,5,5-tetramethyloxolane versus toluene via partition coefficients

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    2,2,5,5-tetramethyloxolane [previously published as 2,2,5,5-tetramethyltetrahydrofuran (TMTHF)] has recently been demonstrated as a greener and cleaner alternative to toluene in several applications. Assessing similarities in properties of toluene and 2,2,5,5-tetramethyloxolane is crucial for establishing this molecules potential to replace traditional non-polar organic solvents in the cleaner production of chemicals and materials. However, the Hansen solubility parameters (HSP) and Kamlet-Taft parameters (KT) give conflicting views on their similarities and differences, which necessitates a full comparative characterisation of the solvation environment of these two solvents. Such comparisons have been achieved through a direct and extensive determination of partition coefficients between each of the two solvents and water. The partition coefficients and Abraham's solvation parameter model have quantitatively clarified the similarities and differences in properties of 2,2,5,5-tetramethyloxolane and toluene. Solutes of high dipolarity and hydrogen-bond accepting ability tended to favour the aqueous phase in both systems, while large molar volume and high refractive indices favoured the organic phase. A significant difference between 2,2,5,5-tetramethyloxolane and toluene was observed for hydrogen-bond donating solutes. In general, such solutes strongly preferred the aqueous phase in the toluene/water system but preferred the organic phase in the 2,2,5,5-tetramethyloxolane/water system. This was due to the interaction of the protic solutes with the lone pairs of electrons on the ethereal oxygen of 2,2,5,5-tetramethyloxolane, a feature that is not present on toluene, and opens up new possibilities for applications of this sustainable solvent in liquid-liquid extraction, particularly in the isolation of natural products. As toluene is such an important solvent in the chemical industry, its replacement with a greener alternative such as 2,2,5,5-tetramethyloxolane would be hugely significant for cleaner synthesis, extractions and separations

    Synthesis of cholesterol-reducing sterol esters by enzymatic catalysis in bio-based solvents or solvent-free

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    Enzymatic synthesis of a β-sitosterol ester in bio-based solvents was compared with conventional solvents. Limonene and p-cymene gave higher initial reaction rates than n-hexane, and comparable conversions after 24 hours (∼75%). Importantly, a solvent-free system yielded the highest conversion (88%)

    Pancreatic cysts suspected to be branch duct intraductal papillary mucinous neoplasm without concerning features have low risk for development of pancreatic cancer.

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    BackgroundThe risk of developing pancreatic cancer is uncertain in patients with clinically suspected branch duct intraductal papillary mucinous neoplasm (BD-IPMN) based on the "high-risk stigmata" or "worrisome features" criteria proposed in the 2012 international consensus guidelines ("Fukuoka criteria").MethodsRetrospective case series involving patients referred for endoscopic ultrasound (EUS) of indeterminate pancreatic cysts with clinical and EUS features consistent with BD-IPMN. Rates of pancreatic cancer occurring at any location in the pancreas were compared between groups of patients with one or more Fukuoka criteria ("Highest-Risk Group", HRG) and those without these criteria ("Lowest-Risk Group", LRG).ResultsAfter exclusions, 661 patients comprised the final cohort (250 HRG and 411 LRG patients), 62% female with an average age of 67 years and 4 years of follow up. Pancreatic cancer, primarily adenocarcinoma, occurred in 60 patients (59 HRG, 1 LRG). Prevalent cancers diagnosed during EUS, immediate surgery, or first year of follow up were found in 48/661 (7.3%) of cohort and exclusively in HRG (33/77, 42.3%). Using Kaplan-Meier method, the cumulative incidence of cancer at 7 years was 28% in HRG and 1.2% in LRG patients (P<0.001).ConclusionsThis study supports using Fukuoka criteria to stratify the immediate and long-term risks of pancreatic cancer in presumptive BD-IPMN. The risk of pancreatic cancer was highest during the first year and occurred exclusively in those with "high-risk stigmata" or "worrisome features" criteria. After the first year all BD-IPMN continued to have a low but persistent cancer risk

    Supercritical extraction of biomass as an effective pretreatment step for the char yield control in pyrolysis

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    peer-reviewedThis work demonstrates that the coupling of supercritical carbon dioxide extraction with pyrolysis is an effective method for the removal of extractives from forestry residues and generation of solid char with different properties from the remaining solid wood fractions. Extraction of the needles and stumps shows greater yields of resin acids, terpenes, steroids and other derivatives than that of pinewood bark, cones and branches. The char yields of both non-treated and scCO2 extracted wood fractions varied from approximately 17.5 to 38.5 wt. % on dry basis at fast heating rates. The catalytic effect of extractives is significant on the yields and morphology of solid chars in fast pyrolysis and less pronounced at slow heating rates. These results are promising as they show that both the composition and location of extractives inclusions in the interior of wood particle can affect the morphology of char samples. Moreover, the impact of alkali metals on the wood devolatilization appears to be less compared to the lignocellulosic composition in slow pyrolysis. These results demonstrate that supercritical carbon dioxide extraction can be integrated in biorefinery as a pretreatment step to control the properties of pyrolysis products by varying the heating rate
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