Emissions of CO2 and N2O from a pasture soil from Madagascar—Simulating conversion to direct‐seeding mulch‐based cropping in incubations with organic and inorganic inputs          下载免费PDF全文

Michel Rabenarivo  Nicole Wrage‐Moennig  Jean‐Luc Chotte  Lilia Rabeharisoa  Tantely M. Razafimbelo  Lydie Chapuis‐Lardy 《植物养料与土壤学杂志》2014,177(3):360-368

In the highlands of Madagascar, agricultural expansion gained on grasslands and cropping systems based on direct seeding with permanent vegetation cover are emerging as a means to sustain upland crop production. The objective of this study was to examine how such agricultural practices affect greenhouse‐gas emissions from a loamy Ferralsol previously used as a pasture. We conducted an experiment under controlled laboratory conditions combining cattle manure, crop residues (rice straw), and mineral fertilizers (urea plus NPK or di‐NH₄‐phosphate) to mimic on‐field inputs and examined soil CO₂ and N₂O emissions during a 28‐d incubation at low and high water‐filled pore space (40% and 90% WFPS). Emissions of N₂O from the control soil, i.e., soil receiving no input, were extremely small (< 5 ng N₂O‐N (g soil)^–1 h^–1) even under anaerobic conditions. Soil moisture did not affect the order of magnitude of CO₂ emissions while N₂O fluxes were up to 46 times larger at high soil WFPS, indicating the potential influence of denitrification under these conditions. Both CO₂ and N₂O emissions were affected by treatments, incubation time, and their interactions. Crop‐residue application resulted in larger fluxes of CO₂ but reduced N₂O emissions probably due to N immobilization. The use of di‐NH₄‐phosphate was a better option than NPK to reduce N₂O emissions without increasing CO₂ fluxes when soil received mineral fertilizers. Further studies are needed to translate the findings to field conditions and relate greenhouse‐gas budgets to crop production.  相似文献   

Does time or habitat make old-growth forests species rich? Bryophyte richness in boreal Picea mariana forests     

Nicole J. Fenton  Yves Bergeron 《Biological conservation》2008,141(5):1389-1399

The relative importance of time since disturbance and habitat variables in creating diversity in old-growth forests will influence conservation strategies. However, the independent roles of these factors are not well understood, as they are rarely examined independently. This study examines the respective roles of habitat variables and time (stand age) in determining bryophyte diversity in Picea mariana (Mill. (BSP)) forests. Bryophytes are frequently used as indicators of old-growth forest, but their true dependence on forest continuity is unknown. Bryophytes were classified into taxonomic-habitat guilds: true mosses (forest), forest liverworts, bog liverworts and sphagna (bog). Diversity increased with age and peaked at approximately 275 years since fire, driven by liverworts. Multiplicative habitat modeling indicated that time and habitat played different roles for the different taxonomic-habitat guilds. True mosses and forest liverworts were primarily influenced by habitat variables, while sphagna and bog liverworts were influenced by time and habitat variables. The models for sphagna were particularly strong, indicating that many important factors were included, while forest liverwort models were particularly weak. This unexplained variability may represent site specific random factors, such as secondary disturbances that create habitat in a fully occupied space. Overall, high richness was created by small species dependent on habitat variables and chance factors for establishment. Therefore, time since disturbance was not the primary factor limiting richness in these forests. These results suggest that in boreal North America, where forest fragmentation is limited and recent, conservation strategies that emphasize habitat variables rather than forest continuity may be effective for some bryophytes.  相似文献   

Analysis of agricultural residues on tea using d-SPE sample preparation with GC-NCI-MS and UHPLC-MS/MS   总被引：1，自引：0，他引：1  

Zhang X  Mobley N  Zhang J  Zheng X  Lu L  Ragin O  Smith CJ 《Journal of agricultural and food chemistry》2010,58(22):11553-11560

This study presents new sample preparation and analytical procedures for the quantification of pesticides on processed tea leaves. The new method includes tea extraction and dispersive solid phase extraction (d-SPE) to prepare gas chromatography (GC) and ultrahigh-performance liquid chromatography (UHPLC)-ready samples, providing a fast and cost-effective solution for time-sensitive industrial analysis to fulfill regulatory requirements. Both GC-negative chemical ionization mass spectrometry (GC-NCI-MS) and UHPLC-tandem mass spectrometry (UHPLC-MS/MS) were employed to produce highly sensitive and reproducible data. Excellent limits of detection (typically below 1 μg/kg for GC and 10 μg/kg for UHPLC), wide linearity ranges, and good recoveries (mostly >70%) were achieved on the selected pesticides. Twenty-seven tea samples purchased from local grocery stores were analyzed using the newly developed methods. Among the pesticides analyzed, endosulfan sulfate and kelthane were the most frequently detected by GC-NCI-MS and imidacloprid and acetamiprid by UHPLC-MS/MS in these teas. The samples were found to be relatively clean, with <1 mg/kg of total pesticide residues. The organic-labeled teas were significantly cleaner than nonorganic ones. The cost per gram of tea did not correlate with pesticide residue levels detected.  相似文献   

Sensitivity and specificity improvement of an ion sensitive field effect transistors-based biosensor for potato glycoalkaloids detection     

Korpan YI  Raushel FM  Nazarenko EA  Soldatkin AP  Jaffrezic-Renault N  Martelet C 《Journal of agricultural and food chemistry》2006,54(3):707-712

Butyryl cholinesterase of different origin along with variations of the time of enzyme immobilization on the potentiometric transducer surface is offered to control the ion sensitive field effect transistor (ISFET)-based biosensor sensitivity. Because butyryl cholinesterase has been already used to develop the sensors for heavy metals, organophosphorus/carbamate pesticides, and steroidal glycoalkaloids analysis, the present study has been focused on the investigation and adjustment of the ISFET-based biosensor specificity exclusively to the glycoalkaloids. Utilization of ethylendiaminetetracetate (a complexon of heavy metal ions) and phosphotriesterase (a highly efficient catalyst for the hydrolysis of organophosphorus compounds) enabled the highly specific determination of glycoalkaloids at the background of lead and mercury (up to 500 microM of ions concentration) and paraoxon (up to 100 microM of pesticide concentration). The developed biosensor has been validated for glycoalkaloids detection in potato varieties cultivated in Ukraine, and the results obtained are compared to those measured by the methods of HPLC and TLC.  相似文献   

Changes in headspace volatile concentrations of coffee brews caused by the roasting process and the brewing procedure     

López-Galilea I  Fournier N  Cid C  Guichard E 《Journal of agricultural and food chemistry》2006,54(22):8560-8566

Headspace-solid-phase microextraction technique (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to characterize the aroma compounds of coffee brews from commercial conventional and torrefacto roasted coffee prepared by filter coffeemaker and espresso machine. A total of 47 volatile compounds were identified and quantified. Principal component analysis (PCA) was applied to differentiate coffee brew samples by volatile compounds. Conventional and torrefacto roasted coffee brews were separated successfully by principal component 1 (68.5% of variance), and filter and espresso ones were separated by principal component 2 (19.5% of variance). By GC olfactometry, a total of 34 aroma compounds have been perceived at least in half of the coffee extracts and among them 28 were identified, among which octanal was identified for the first time as a contributor to coffee brew aroma.  相似文献   

The psychological consequences of money   总被引：1，自引：0，他引：1  

Vohs KD  Mead NL  Goode MR 《Science (New York, N.Y.)》2006,314(5802):1154-1156

Money has been said to change people's motivation (mainly for the better) and their behavior toward others (mainly for the worse). The results of nine experiments suggest that money brings about a self-sufficient orientation in which people prefer to be free of dependency and dependents. Reminders of money, relative to nonmoney reminders, led to reduced requests for help and reduced helpfulness toward others. Relative to participants primed with neutral concepts, participants primed with money preferred to play alone, work alone, and put more physical distance between themselves and a new acquaintance.  相似文献   

Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus     

Bennett N  Greco DS  Peterson ME  Kirk C  Mathes M  Fettman MJ 《Journal of Feline Medicine and Surgery》2006,8(2):73-84

This study compared the effects of a moderate carbohydrate-high fiber (MC-HF) food and a low carbohydrate-low fiber (LC-LF) food on glycemic control in cats with diabetes mellitus. Sixty-three diabetic cats (48 male castrated, 15 female spayed) were randomly assigned to be fed either a canned MC-HF (n = 32) food or a canned LC-LF (n = 31) food for 16 weeks. Owners were blinded to the type of diet fed. CBC, urinalysis, serum chemistry panel, fructosamine concentration and thyroxine concentration were determined on initial examination, and a complete blood count, serum chemistry panel, urinalysis and serum fructosamine concentration were repeated every 4 weeks for 16 weeks. Insulin doses were adjusted as needed to resolve clinical signs and lower serum fructosamine concentrations. Serum glucose (P = 0.0001) and fructosamine (P = 0.0001) concentrations significantly decreased from week 0 to week 16 in both dietary groups. By week 16, significantly more of the cats fed the LC-LF food (68%, 22/31), compared to the cats fed the MC-HF food (41%, 13/32), had reverted to a non-insulin-dependent state (P = 0.03). Cats in both groups were successfully taken off of insulin regardless of age, sex, type of insulin administered or duration of clinical disease before entering the study. There was no significant difference in the initial or final mean body weights or in the mean change in body weight from week 0 to week 16 between dietary groups. Diabetic cats in this study were significantly more likely to revert to a non-insulin-dependent state when fed the canned LC-LF food versus the MC-HF food.  相似文献   

Overcoming barriers: Myanmar's recent elections and women's political participation          下载免费PDF全文

Nicole Loring 《Asia Pacific viewpoint》2018,59(1):74-86

Myanmar's 2015 elections have been credited with bringing about a myriad of changes within the country. Much has been written about the changing political climate within Myanmar. One topic which has not yet been discussed adequately, however, is the role of Burmese women in these recent elections. This paper seeks to examine women's political participation in Myanmar's recent move towards democratisation. Using rates of female candidacies in Burmese elections, comparing these figures with rates of female participation in other Southeast Asian countries, and ethnographic research with the Burmese voting public, this paper will contribute to the sparse scholarship regarding the role of women in new democracies and regime transitions. This paper finds that beliefs about traditional gender roles, rooted in traditional Buddhism, still shape the way both men and women in Myanmar view women's political participation. While women are better represented in Myanmar's government than they were in the past, this paper suggests that measures such as quotas or reserved seats based on gender may be the best way to increase Burmese women's political representation in the future.  相似文献   

Seasonal acoustic occurrence of blue,fin, and North Atlantic right whales in the New York Bight          下载免费PDF全文

Charles A. Muirhead  Ann M. Warde  Ingrid S. Biedron  A. Nicole Mihnovets  Christopher W. Clark  Aaron N. Rice 《水产资源保护:海洋与淡水生态系统》2018,28(3):744-753

Indirect computed tomography lymphangiography with aqueous contrast for evaluation of sentinel lymph nodes in dogs with tumors of the head          下载免费PDF全文

Janet A. Grimes  Scott A. Secrest  Nicole C. Northrup  Corey F. Saba  Chad W. Schmiedt 《Veterinary radiology & ultrasound》2017,58(5):559-564

Sentinel lymph node evaluation is widely used in human medicine to evaluate the first lymph node(s) to which a tumor drains. Sentinel lymph node biopsy allows avoidance of extensive lymphadenectomies in cases where the sentinel lymph node is negative for metastasis, thereby reducing patient morbidity. It has been shown that regional lymph nodes are not always the sentinel lymph node, thus identification and sampling of sentinel lymph nodes allows for more accurate staging, which is critical for treatment and prognostication in dogs with cancer. The objective of this prospective, pilot study was to determine if indirect computed tomography (CT) lymphangiography with aqueous contrast agent would successfully allow identification of sentinel lymph nodes in dogs with masses on the head. Eighteen dogs underwent CT lymphangiography. The sentinel lymph node was successfully identified within 3 min of contrast injection in 16 dogs (89%). Compression of lymphatic vessels from endotracheal tube ties and/or the patient's own body weight delayed or prevented identification of sentinel lymph nodes in two dogs (11%). Computed tomography lymphangiography with aqueous contrast can be used successfully to rapidly identify sentinel lymph nodes in dogs with masses on the head.  相似文献