National Service: can we afford it?

This thesis estimates the costs, implicit as well as explicit, of three National Service proposals. The three proposals examined were: (1) a completely voluntary system as presented by Donald Eberly, the Director of the National Service Secretariat; (2) a "coercive-voluntary" model developed by Richard Danzig and Peter Szanton in their book "National Service: What Would it Mean?"; and (3) a mandatory system similar to the military draft of the Vietnam War era. Costs included were: wages, medical benefits/coverage, GI Bill benefits, administrative costs, basic and specialized training costs, operational costs and recruiting/advertising costs. Additionally, implicit (i.e., opportunity) costs were included in Models Two and Three. Estimates were made only of the costs of the programs. The assessment of potential benefits from an untested program is even more problematic than the attempt to estimate economic costs and is beyond the scope of this thesis. This research indicates that previous estimates of the costs of National Service programs may be underestimated by several billion dollars. In all probability, these estimates were low due to the unintentional exclusion of certain relevant costs, such as training and implicit costs. However, it is also possible that conservative assumptions were used in many previous estimates to make national service more politically appealing. It was found that the voluntary model of Eberly is the least costly, but is also unrealistic. Greater expenditures in wages and benefits would be necessary to provide enough incentives to enlist sufficient volunteers. This thesis suggests a program that provides better incentives for volunteers and presents a more realistic cost of a voluntary system. It is found that the term "National Service," as used in this context, more accurately describes a job creation program for lower income youth than a service program designed to attract youth from a cross-section of American society.http://archive.org/details/nationalservicec00deboNAN

Bodemmicrobiologie als indicator voor bodemkwaliteit?

De Rusch-test is een relatief goedkope en eenvoudige microbiologische test die werd ontwikkeld door dokter en wetenschapper Hans Peter Rusch uit Duitsland, maar tot hiertoe weinig toepassing gekend heeft. De doelstelling van dit project was na te gaan of de Rusch-test kan dienen als indicator voor een goede bodemkwaliteit en of deze eenvoudige test, voor de teler interessante info kan opleveren in verband met de gevolgde of te volgen teeltpraktijk. Hiervoor werd in het eerste luik van het project, op verschillende biologische percelen in Vlaanderen, gedurende twee jaren, de bodemmicrobiologie door middel van drie verschillende methodes bepaald (Rusch, PLFA en DGGE). Naast het analyseren van de bodemmicrobiologie, werden tijdens het eerste jaar ook een aantal chemische indicatoren voor de bodemkwaliteit bepaald. Vervolgens werden een aantal kennisuitwisselingsmomenten georganiseerd over deze verschillende methodes en over de relaties tussen het microbieel leven in de bodem en het bodembeheer in de praktijk

Biochar-amended potting medium reduces the susceptibility of rice to root-knot nematode infections

Background: Biochar is a solid coproduct of biomass pyrolysis, and soil amended with biochar has been shown to enhance the productivity of various crops and induce systemic plant resistance to fungal pathogens. The aim of this study was to explore the ability of wood biochar to induce resistance to the root-knot nematode (RKN) Meloidogyne graminicola in rice (Oryza sativa cv. Nipponbare) and examine its histochemical and molecular impact on plant defense mechanisms. Results: A 1.2 % concentration of biochar added to the potting medium of rice was found to be the most effective at reducing nematode development in rice roots, whereas direct toxic effects of biochar exudates on nematode viability, infectivity or development were not observed. The increased plant resistance was associated with biochar-primed H2O2 accumulation as well as with the transcriptional enhancement of genes involved in the ethylene (ET) signaling pathway. The increased susceptibility of the Ein2b-RNAi line, which is deficient in ET signaling, further confirmed that biochar-induced priming acts at least partly through ET signaling. Conclusion: These results suggest that biochar amendments protect rice plants challenged by nematodes. This priming effect partially depends on the ET signaling pathway and enhanced H2O2 accumulation

Tapping into the maize root microbiome to identify bacteria that promote growth under chilling conditions

Background When maize (Zea mays L.) is grown in the Northern hemisphere, its development is heavily arrested by chilling temperatures, especially at the juvenile phase. As some endophytes are beneficial for plants under stress conditions, we analyzed the impact of chilling temperatures on the root microbiome and examined whether microbiome-based analysis might help to identify bacterial strains that could promote growth under these temperatures. Results We investigated how the maize root microbiome composition changed by means of 16S rRNA gene amplicon sequencing when maize was grown at chilling temperatures in comparison to ambient temperatures by repeatedly cultivating maize in field soil. We identified 12 abundant and enriched bacterial families that colonize maize roots, consisting of bacteria recruited from the soil, whereas seed-derived endophytes were lowly represented. Chilling temperatures modified the root microbiome composition only slightly, but significantly. An enrichment of several chilling-responsive families was detected, of which the Comamonadaceae and the Pseudomonadaceae were the most abundant in the root endosphere of maize grown under chilling conditions, whereas only three were strongly depleted, among which the Streptomycetaceae. Additionally, a collection of bacterial strains isolated from maize roots was established and a selection was screened for growth-promoting effects on juvenile maize grown under chilling temperatures. Two promising strains that promoted maize growth under chilling conditions were identified that belonged to the root endophytic bacterial families, from which the relative abundance remained unchanged by variations in the growth temperature. Conclusions Our analyses indicate that chilling temperatures affect the bacterial community composition within the maize root endosphere. We further identified two bacterial strains that boost maize growth under chilling conditions. Their identity revealed that analyzing the chilling-responsive families did not help for their identification. As both strains belong to root endosphere enriched families, visualizing and comparing the bacterial diversity in these communities might still help to identify new PGPR strains. Additionally, a strain does not necessarely need to belong to a high abundant family in the root endosphere to provoke a growth-promoting effect in chilling conditions

Stuurbaar bodemleven? Effect van lignine-rijke gewasresten op Verticillium

In de biologische glastuinbouw is een goede bodemgezondheid van cruciaal belang. Het streven is om een systeem te ontwikkelen met meer veerkracht en een betere bodemweerbaarheid. In dit onderzoek wordt het bodemleven gevoed met lignine-rijke gewasresten. Het doel is om de natuurlijk voorkomende witrotschimmels te stimuleren die lignine omzetten, en daarmee ook de overlevingsstructuren (microsclerotiën) van plant-pathogene Verticillium schimmels af te breken. Houtige gewassen bevatten het meeste lignine, gevolgd door grassen en granen. Ook gewasresten van broccoli en boon bevatten relatief veel lignine. In een laboratorium proef is grond van twee bedrijven met een natuurlijke besmetting met Verticillium dahliae gemengd met 7 lignine-rijke gewasresten. De twee gronden reageerden verschillend. Op locatie Schalkwijk (rivierklei) hadden maïsstengels, broccoli, rietstengels en Japanse haver (Avena strigosa av. astrigosa) een significant effect op de hoeveelheid levensvatbare microsclerotiën in de bodem. In 4 weken is in de variant met 10% (m/m) maïsstengels de hoeveelheid Verticillium met 69% afgenomen ten opzichte van de controle. Op locatie Tinte (zeeklei) hadden alleen rietblad en rietstengel een significant effect. Door toevoeging van rietblad (10% m/m) neemt de hoeveelheid Verticillium met 66% af. Op locatie Tinte is er een significante relatie tussen de hoeveelheid toegevoegde lignine en de afname van het aantal microsclerotiën van Verticillium. Voor locatie Schalkwijk is dit verband niet gevonden, hier spelen mogelijk andere mechanismen een rol. In de potproef is 1, 2 en 10% (m/m) riet en 2% tarwestro ingewerkt in van nature met Verticillium besmette grond. Na 12 weken zijn in de variant met 2% riet 75% minder microsclerotiën van Verticillium aanwezig dan in de controle, maar deze afname is niet significant. Resultaten van real-time PCR analyse laten echter wel een significante afname van de hoeveelheid Verticillium zien, in de varianten waar 1% en 10% riet is ondergewerkt. Bij toenemende percentages riet, neemt ook de immobilisatie van stikstof significant toe. Stro veroorzaakt meer immobilisatie dan riet. In de praktijkproef is 2% (m/m) riet ondergewerkt. Na 3 weken is er op het perceel paprika geplant. Na in totaal 12 weken is de afname van de hoeveelheid Verticillium bepaald. Uitplaten laat een lichte stijging zien van de hoeveelheid Verticillium in de controle, terwijl in de behandeling met 2% riet de hoeveelheid Verticillium afneemt. Deze verschillen zijn echter niet significant. Bij de real-time PCR analyse zien we een significant effect van het bemonsteringstijdstip. In december is er meer DNA van Verticillium in de bodem dan in maart. Dit is echter ook in de controle het geval. Er is dus geen significant effect meetbaar van het toevoegen van de gewasresten aan de bodem. In alle experimenten is veel meer Verticillium tricorpus aanwezig dan Verticillium dahliae. V. dahliae kan al in zeer kleine hoeveelheden gewasschade aanbrengen. De rol van V. tricorpus is onduidelijk. DNA sequencing van een isolaat van V. tricorpus op het betreffende glastuinbouw bedrijf laat zien dat deze soort geclassificeerd kan worden als Verticillium isaacii. Het is noodzakelijk een goed beeld te krijgen van de aanwezige Verticillium soorten en hun pathogeniciteit voordat nieuwe bestrijdingsmethoden van Verticillium verder ontwikkeld worden

Bone size and bone strength are increased in obese male adolescents

Context: Controversy exists on the effect of obesity on bone development during puberty. Objective: Our objective was to determine differences in volumetric bone mineral density (vBMD) and bone geometry in male obese adolescents (ObAs) in overlap with changes in bone maturation, muscle mass and force development, and circulating sex steroids and IGF-I. We hypothesized that changes in bone parameters are more evident at the weight-bearing site and that changes in serum estradiol are most prominent. Design, Setting, and Participants: We recruited 51 male ObAs (10-19 years) at the entry of a residential weight-loss program and 51 healthy age-matched and 51 bone-age-matched controls. Main Outcome Measures: vBMD and geometric bone parameters, as well as muscle and fat area were studied at the forearm and lower leg by peripheral quantitative computed tomography. Muscle force was studied by jumping mechanography. Results: In addition to an advanced bone maturation, differences in trabecular bone parameters (higher vBMD and larger trabecular area) and cortical bone geometry (larger cortical area and periosteal and endosteal circumference) were observed in ObAs both at the radius and tibia at different pubertal stages. After matching for bone age, all differences at the tibia, but only the difference in trabecular vBMD at the radius, remained significant. Larger muscle area and higher maximal force were found in ObAs compared with controls, as well as higher circulating free estrogen, but similar free testosterone and IGF-I levels. Conclusions: ObAs have larger and stronger bones at both the forearm and lower leg. The observed differences in bone parameters can be explained by a combination of advanced bone maturation, higher estrogen exposure, and greater mechanical loading resulting from a higher muscle mass and strength

Trichoderma-Inoculated Miscanthus straw can replace peat in strawberry cultivation, with beneficial effects on disease control

Peat based growing media are not ecologically sustainable and often fail to support biological control. Miscanthus straw was (1) tested to partially replace peat; and (2) pre-colonized with a Trichoderma strain to increase the biological control capacity of the growing media. In two strawberry pot trials (denoted as experiment I & II), extruded and non-extruded miscanthus straw, with or without pre-colonization with T. harzianum T22, was used to partially (20% v/v) replace peat. We tested the performance of each mixture by monitoring strawberry plant development, nutrient content in the leaves and growing media, sensitivity of the fruit to the fungal pathogen Botrytis cinerea, rhizosphere community and strawberry defense responses. N immobilization by miscanthus straw reduced strawberry growth and yield in experiment II but not in I. The pre-colonization of the straw with Trichoderma increased the post-harvest disease suppressiveness against B. cinerea and changed the rhizosphere fungal microbiome in both experiments. In addition, defense-related genes were induced in experiment II. The use of miscanthus straw in growing media will reduce the demand for peat and close resource loops. Successful pre-colonization of this straw with biological control fungi will optimize crop cultivation, requiring fewer pesticide applications, which will benefit the environment and human health

Quantification of extracellular proteases and chitinases from marine bacteria

A total of 92 marine bacteria belonging to Pseudomonas, Pseudoalteromonas, Psychrobacter, and Shewanella were first screened for their proteolytic activity. In total, four Pseudomonas strains belonging to Ps. fluorescens, Ps. fragi, Ps. gessardii, and Ps. marginalis; 14 Pseudoalteromonas strains belonging to Psa. arctica, Psa. carrageenovora, Psa. elyakovii, Psa. issachenkonii, Psa. rubra, Psa. translucida, and Psa. tunicata; and two Shewanella strains belonging to S. baltica and S. putrefaciens were identified to have a weak to high proteolytic activity (from 478 to 4445 mU/mg trypsin equivalent) against skim milk casein as protein source. Further chitinolytic activity screening based on these 20 proteolytic strains using colloidal chitin yielded five positive strains which were tested against three different chitin substrates in order to determine the various types of chitinases. Among the strains that can produce both proteases and chitinases, Psa. rubra DSM 6842T expressed not only the highest proteolytic activity (2558 mU/mg trypsin equivalent) but also the highest activity of exochitinases, specifically, β-N-acetylglucosaminidase (6.33 mU/107 cfu) as well. We anticipate that this strain can be innovatively applied to the valorization of marine crustaceans side streams