5,882 research outputs found
Harmony vs. autonomy: models of agricutural fertility among the Dogon and the Kapsiki
No full text
Most of the papers included in this volume were presented at a symposium held at Uppsala University, Sweden, in August 1987. An introduction by A. Jacobson-Widding and W. van Beek on the theme developed in the book, African folk models of fertility, is followed by three parts: I. Fertility from above, fertility from below (A. Jacobson-Widding on the fertility of incest; J.-P. Jacob on the Winye Gurunsi of Burkina Faso; J. Zwernemann on the Kasena, the Nuna (Burkina Faso, Ghana), and the Moba (Togo, Ghana); R. Devisch on the Yaka (Zaire); G. Dahl on the Borana (Kenya); M. Udvardy on the Giriama (Kenya); 2. Fertility from the wilderness (J. Hultin on the Macha Oromo (Ethiopia); P. Brandstr”m on the Sukuma-Nyamwezi (Tanzania); T. H†kansson on the Gusii (Kenya); K. rhem on the Maasai (Kenya, Tanzania); 3. The fertility of social communion (P. Baxter on the Oromo; A.-I. Berglund on the Zulu (southeastern Africa); L. Brydon on the people of Avatime in Ghana; W. van Beek on the Dogon (Mali) and the Kapsiki (Cameroon); M. Whyte on the Nyole of Uganda; and P. Riesman on the Fulbe and RiimaayBe of Burkina Faso)ASC – Publicaties niet-programma gebonde
Phosphate retention by soil in relation to waste disposal
No full textThe disposal of large amounts of domestic sewage water and liquid manure, both containing dissolved phosphates, is often problematic. Discharge of these into (shallow and standing) surface waters is highly undesirable, as phosphate is considered to be one of the prime causes of eutrophication. If, on the other hand, these materials are disposed of onto land, losses of P from soil via surface runoff and leaching are likely to increase, thus contributing again to eutrophication phenomena. An additional reason for concern about increased leaching losses in the case discussed is found in the simultaneous addition of large amounts of water. This may rapidly transport the phosphate to deeper layers, enhancing the chance of penetration into ground- or drainage water.In the present text it was attempted to construct a model describing the movement of phosphate through soil following sizable applications of water. Such a model requires in the first place a quantitative insight into the kinetics of the processes governing the retention of phosphate in soil.Since only scant information is available about phosphate retention in soils treated with soluble phosphate compounds, extensive analytical data were collected from a sandy soil profile that had been exposed to regular applications of (raw) sewage water during a period of about 45 years. As a result of these sewage water additions, phosphates accumulated in the soil, mainly in the top 50 em. Fractionation of these accumulated forms of phosphate via selective extraction methods indicated that aluminum- and ironbound phosphates constitute the largest fraction (60-75%). Organicbound phosphates and calcium-bound phosphates were present in smaller quantities. Phosphate analysis of sewage water and effluent leaving the soil via a system of tile drains indicated that, in spite of 45 years prior usage, the removal of phosphate from the sewage water by the soil is still very effective (around 90%). Moreover, some other substances were partly or nearly completely removed from the sewage water, during its percolation through the soil (Chapter 3).In view of the above findings indicating that aluminum (and iron) were the main binding agents for phosphate, the total and oxalate extractable forms of these components were determined in the soil. These results strongly suggested that in the top layers (0-50) cm of the soil treated with sewage water accumulation of aluminum compounds had taken place in the past, most likely due to the supply of sewage water containing industrial waste water. Additional experiments showed, furthermore, that the phosphate binding capacity of different sandy soils could be related to the oxalate extractable forms of aluminum and iron. Under conditions as were found in soils treated with sewage water, the molar ratio of oxalate extractable (Al+Fe) over the phosphate retained tended to a value around three. A determination of the oxalate extractable aluminum plus iron thus presents a simple method to obtain a fair estimate of the phosphate bonding capacity of sandy soils, thereby assuming that the above value of the ratio (Al+Fe)/P remains valid (Chapter 4).Kinetic aspects of the retention processes of dissolved orthophosphate with soil were studied with the help of batch shaking experiments, using samples of the soil treated with sewage water (Chapter 5). The samples were suspended in solutions containing most of the inorganic ions that were present in the sewage water, at the same concentrations. The soil suspensions were brought to pH 6.2 and adjusted when necessary. Determination of dissolved P as a function of time showed that P was removed rapidly from the solution initially, followed by a much slower rate of removal over longer periods. With the help of a graphical procedure the contributions of the fast and slow processes were separated out; adsorption processes were considered to be responsible for the fast removal, whereas the slow rate of removal was associated with the formation of a rather insoluble and non-reactive form of solid phosphate, presumably a (calcium) aluminum-phoshate.The equilibrium adsorption processes could be described with two Langmuir equations, which lead to the introduction, in the model. of two pools of adsorbed phosphate, i.e. X 1 and X 2 . In addition a third pool of solid phosphate was distinguished, viz pool N, comprising the solid phosphate compounds formed during slow retention processes. This division of retained phosphates into an adsorbed fraction and another immobilized form was supported by results of isotopic exchange experiments using 32P. It was found that the adsorbed forms present in the pools X 1 and X 2 were relatively readily accessible to isotopic exchange whereas forms of phosphate present in pool N were rather inaccessible to exchange with 32P labelled species in solution.An important feature associated with the formation of phosphate in pool N was the apparent freeing of adsorption sites, suggesting that during the slow retention process part of the adsorbed phosphate was released from the adsorption sites.The decrease of the phosphate concentration in the soil sus pensions was described in terms of three rate equations. The reactions leading to the formation of the forms of phosphate present in the pools X 1 and X 2 were treated as simple first order reactions, the rate being proportional to the 'excess' concentration. The rate constants k1 and k2 ,defining the loading of pools XX 1 and X 2 , respectively, were derived from adsorption experiments. It was shown that k1 differed significantly from k2 viz, k1/k2 ≈ 50. Since it was the main objective to study the retention of phosphate, only super ficial attention was paid to desorption processes. The rate constants for desorption, kd1 and kd2 were therefore given the same values as the constants k1 and k2 , although there are indications that the ensuing assumption of reversible adsorption is an oversimplification. The loading of pool N was defined as a second order equation, the rate being proportional to the 'excess' adsorbed phosphate present in pool X 2 , implying that P present in pool N is formed at the cost of P present in pool X 2 . Since the formation of P in pool N must involve a P-binding agent with limited supply for a given soil, a delimiting factor was introduced in the form of an available capacity. This factor was related to the oxalate extrac table amounts of Al and Fe present in the soil. The rate constant of this slow reaction k ' n , is presumably independent of the 'excess' amount adsorbed in pool X 2 and the available capacity of the P binding agent.On the basis of the presumed three pools of solid phosphate and a pool of dissolved phosphate a simulation model was developed; the transformation processes between the different pools were formulated on the basis of the rate equations written in the simulation language CSMPIII. Computed results were compared with experimental data of phosphate concentrations in solution of the soil suspensions to check the model. Finally short soil columns were assembled in the laboratory and subjected to percolation with a phosphate solution. The phosphate concentrations in the effluent leaving the column were used to test the computed result obtained with the model under conditions of liquid flow. To this purpose the model was extended with equations describing transport of phosphate by convective and diffusion/dispersion flow (cf. Chaper 5). The computed effluent concentration agreed satisfactorily with measured concentrations.Since the cheek with column experiments indicated that the model could be used under conditions of liquid flow, it was applied to predict the effects of longterm additions of soluble (ortho)phosphate to the soil (Chapter 6). As for the present purpose the model required initially a long computing time, special procedures were introduced to reduce the latter to an acceptable level.The reliability of the model for longterm predictions was checked against available field data of the scil treated with sewage water. To this purpose the distribution profile of accumulated (AI+Fe)-bound phosphate found in the field was compared with the computed data obtained after a load of phosphate was supplied identical to the (Al+Fe)-bound P present in the field. This load was equivalent to 4460 kg P/ha; in the program it was supplied in separate portions of 19.6 kg P/ha in the form of a solution containing 9.8 mg P/l. An application regime was sustained consisting of 10 applications per year, as is the normal practice used at the sewage farm. The agreement between the 2 sets of data was good from a practical standpoint, showing that the accumulated phosphate was mainly present in the top 30 cm with very little movement to deeper layers. On a more detailed scale, the field profile was definitely more spread-out than the computed one, very probably because the dispersive properties of the field soil differed from the ones present in the model, where only one dimensional leaching was considered. The downward transport of P appeared to be subcritical with respect to the chosen values of the rate constants and the yearly dose.A partly loaded soil was used to study the effects of different application regimes, yearly loads, different fluxes and reduced values of the rate constants on the downward movement of P. To this purpose, the fraction of added phosphate that moved below a depth of 50 em and the fraction of P lost from the soil via leaching (viz. at a depth of 1 meter) were used as criterions. The total amount of P supplied during these cases was always identical to the additional amount that could be bound in the top 50 em. It could be shown that a variation in yearly load of 200 to 780 kg/ha, added in portions of different size, had only a small effect on the downward transport of P. A variation in the waterflux between 10 and 50 cm/day had the same minor effect on downward transport. A reduction of the rate constants controlling the loading of the pools X 1 and X 2 below 10% of their original values leads to higher leaching losses. A reduction of the rate constant defining the loading of pool N below 50% of the original value significantly increased the downward movement of P.These calculations have shown that an application regime and yearly dose as are in use at the sewage farm studied, guarantee an effective removal of phosphate from solution. Of particular importance is the introduction of a sufficient waiting period between two doses, in order to allow for transformation of the adsorbed P to a less reactive form. This then leads to a regeneration of adsorption sites which is of great importance to remove the phosphate effectively from the sewage water during its relatively short residence time in the soil.Finally the model was used to establish limits with respect to the application regime. These results indicated that the penetration depth of phosphate in the soil could be controlled on the basis of (a) the size of the single dose in relation to the capacity of the fast loading pools X 1 and X 2 and (b) the waiting period between successive doses, provided one does not surpass the maximum retention capacity of the relevant soil layer
Rubus revealii A. Beek & M. P. Widrlechner 2021, sp. nov.
No full textRubus revealii A. Beek & M.P. Widrlechner, sp. nov. (Fig. 7A, B) Primocane erect or high arching, 5-8 mm in diameter, furrowed, with scattered, fine trichomes mostly on ridges. Prickles 3-5 mm broad at base, almost straight, 4-8 mm long. Stipules 7-18 mm, linear to lanceolate, thinly hairy. Petioles 5-8 cm, appressed-pilose, with 5-10 curved or hooked prickles. Leaves palmately 5-foliolate; surfaces adaxially thinly pubescent, mostly along veins, abaxially densely pubescent, sometimes slightly greyish pilose; margins serrate, teeth rather sharp, moderate, almost straight. Central leaflets elliptic, 7-10.5 cm long, base subcordate, truncate, or rounded, apex rather abruptly attenuate; width-length index 0.53-0.68, subtending petiolules 26-33(40)% of the length of the central leaflet. Petiolules of the lowermost leaflets 0-3 mm. Flowering branches hairy. Inflorescences small (on the type, 8.5-13 cm long), cymose or short racemose. Pedicels 10-40 mm, densely hairy, pricklets 0-8, minute. Sepals ovate, 3-4.5 × 5-8(9) mm, patent to reflexed, hairy, (greyish) green with a white margin, unarmed. Petals typically 12-14 mm long, elliptic-obovate. Stamens patent, as long as or slightly longer than green styles. Anthers, ovaries, and receptacle glabrous. HOLOTYPE. — CM, Flora of Pennsylvania, Lycoming Co.: North of Salladasburg by Pa. 84, 24.VIII.1956, H.A. Davis, T. Davis, & W. Davis 11574 (holo-, CM [CM129946, CM129947]) (Fig. 7A, B). REPRESENTATIVE COLLECTIONS. — South AFrica. Freestate, Clarens, along the R 711, 2.II.2018, A. van de Beek 2018.01, L; Kwazulu Natal, road from Vryheid to Louwsburg, 3.2 km before the exit to Louwsburg, southside of the road, 14.II.2018, A. van de Beek 2018.08, L. Swaziland. Along the MR1 south of Piggs Peak, just south of Hawane Christian Life Community Church, 12.II.2018, A. van de Beek 2018.06, L. United States. Illinois, Vermillion County: Middle Fork State Fish & Wildlife Area, 16. VI.1991, M. P . Widrlechner 308, ISC. — Pennsylvania, Bucks County: Bowman’s Hill, rich wooded slopes along Pidcock Creek, 19.VII.1936, J. W . and M. T. Adams 2873, BH; Huntingdon County: 2 miles NE of Franklinville, 14.VIII.1955, H. A., T ., and W. H. Davis 11089, CM; West Virginia, Monongalia County: Morgantown, in pasture by Evansdale, 11.VII.1947, H. A . and T. Davis 8192 and 8193, BH. DISTRIBUTION. — United States. This species “seems to be confined to the eastern states. Bailey gives the range as from New England to Virginia. It is a common, but not a very productive blackberry in old fields and fencerows in the hills of Pennsylvania and West Virginia.’’ (as stated in Davis et al. 1969b: 261). Southern AFrica. Rubus revealii sp. nov. is an invasive species in parts of South Africa, especially in the north of Kwazulu-Natal, the east of the Free State, and the southeast of Mpumelanga, and also in Swaziland. In Kwazulu-Natal, it is accompanied by two other invaders from North America, R. probabilis L.H. Bailey and R. originalis L.H. Bailey. In South African publications (Stirton 1984; Henderson 2001, 2011), these three taxa have usually been considered as forms of R. cuneifolius Pursh. More recently, Sochor (2018) correctly conceived the samples of R. revealii sp. nov. and R. originalis as belonging to the Arguti. PICTURES. — Henderson (2011): 1a and c; 2: the upper series; 3: the upper series. DISTINGUISHING TRAITS. — Rubus revealii sp. nov. has some resemblance to R. laudatus A. Berger. However, the latter has more gradually attenuated and broader leaflets, the central leaflets typically with acute tips, and stronger, leafier racemose inflorescences, except at the extreme western edge of its native range, where it can produce heavily armed, short-flaring inflorescences (Widrlechner 2013).Published as part of Van de Beek, Abraham & Widrlechner, Mark P., 2021, North American species of Rubus L. (Rosaceae) described from European botanical gardens (1789 - 1823), pp. 1789-1823 in Adansonia (3) (3) 43 (8) on pages 79-82, DOI: 10.5252/adansonia2021v43a8, http://zenodo.org/record/468076
Interview Gedeputeerde Mevr. Dwarshuis-van de Beek
No full textDe provincie is van de drie bestuurslagen in Nederland enigszins het ondergeschoven kindje. De burger heeft weinig inzicht in wat de provincie doet en getuige de lage opkomst voor de Provinciale Staten verkiezingen is de binding tussen burger en provinciebestuur matig. Reden om een lid van de Gedeputeerde Staten, het dagelijks bestuur van de provincie, te interviewen. Mevrouw Dwarshuis- van de Beek, sinds maart 2003 Gedeputeerde namens de VVD
FIG. 7A. — Rubus revealii A. Beek & M.P in North American species of Rubus L. (Rosaceae) described from European botanical gardens (1789-1823)
No full textFIG. 7A. — Rubus revealii A. Beek & M.P. Widrlechner, sp. nov. holotype, primocane, H.A. Davis, T. Davis, & W. Davis 11574 (CM[CM129946]).Published as part of Van de Beek, Abraham & Widrlechner, Mark P., 2021, North American species of Rubus L. (Rosaceae) described from European botanical gardens (1789-1823), pp. 1789-1823 in Adansonia (3) 43 (8) on page 84, DOI: 10.5252/adansonia2021v43a8, http://zenodo.org/record/468076
Work ability and fatigue in cancer survivors on long-term sick leave
No full textAnema, J.R. [Promotor]Beek, A.J. van der [Promotor]Duijts, S.F.A. [Copromotor
Passende beoordeling huidig en toekomstig gebruik in Natura 2000-gebied Voordelta: Basis document voor maatregelen pakket beheerplan Voordelta
No full textOnder de Natuurbeschermingswet 1998 (Nb-wet) zal de Voordelta worden aangewezen als Natura 2000-gebied. Een verplichting die voortvloeit uit een aanwijzing in het kader van de Nb-wet is het opstellen van een beheerplan voor het gebied. In dit beheerplan moet duidelijk worden voor de komende 6 jaar welk gebruik is toegestaan en welk gebruik gereguleerd gaat worden. Vanwege de mogelijkheid dat er binnen de Voordelta negatieve effecten optreden door het huidige gebruik en de autonome ontwikkeling daarvan dient een passende beoordeling te worden uitgevoerd. De passende beoordeling richt zich op de toetsing van het huidig gebruik en de autonome ontwikkeling. Tevens wordt bekeken of de maatregelen zoals voorgesteld in het ontwerp beheerplan Voordelta (PMR, 2006 concept 1 december 2006) voldoende zijn om eventuele significante effecten te niet te doen. Indien dit niet het geval is, wordt onderzocht welke mitigerende maatregelen noodzakelijk zijn
Rubus revealii A. Beek & Widrlechner 2021
No full text<p> <b>23.</b> <i>Rubus revealii</i> Beek & Widrlechner (2021: 79).</p> <p> Type:—CM, Flora of Pennsylvania, Lycoming Co.: North of Salladasburg by Pa. 84, 24.8.1956, <i>H.A. Davis</i>, T. Davis & W. <i>Davis</i> 11574 (holotype CM [CM129946, CM129947])</p> <p> <i>Synonym</i>:— <i>Rubus pensilvanicus</i> auct., non Poiret (1804: 246).</p> <p> <i>Primocane</i> (Figs 20A–B) erect or high arching, diam. 5–8 mm, furrowed, (almost) glabrous; prickles with 2–5 mm broad base, almost straight, up to 4–8 mm long; stipules 13–18 mm, linear to lanceolate, brown, thinly hairy. <i>Leaves</i> palmate 5-foliolate, adaxially (Fig. 20C) only along veins with some hairs, abaxially (Fig. 20D) densely, sometimes slightly greyish pilose; serrature sharp, moderate, with straight teeth; petiole 5–14 cm, appressed pilose, with 5–10 curved or hooked prickles; central leaflet with subcordate, emarginate or rounded base, elliptical, rather abruptly attenuate into moderate tip, 70–105 mm long, width–length index 0.53–0.81, length of petiolule 26–45% of length of leaflet; petiolule of basal leaflets 0–3 mm. <i>Flowering branch</i> hairy. <i>Inflorescence</i> (Figs 20E–F) small, ascendateracemose; pedicels 10–40 mm, densely hairy, with 2–8 pricklets. <i>Flowers</i>: sepals 6–8 × 2–3 mm, patent, hairy, (greyish) green with white margin, unarmed; petals large, elliptical; stamens patent, as long as green styles; anthers, ovaries and receptacle glabrous. <i>Fruits</i> shiny red, becoming black (Fig. 20G).</p> <p> <b>Ecology:</b> — <i>Rubus revealii</i> makes often large populations in open fields and along roadsides.</p> <p> <b>Distribution in South Africa:</b> —Common in the eastern Free State (Clarens) and northern KwaZulu-Natal; scattered in Limpopo, Gauteng, and Mpumalanga; also in Swaziland.</p> <p> <b>Specimens:— SOUTH AFRICA. Limpopo</b>: 3 km van Haenertsburg na Boyle, 1984, <i>Stirton 8013</i> & <i>8033</i> (PRE); Naudé Dam, 2 December 1975, <i>Stirton 5747</i> (PRE). <b>Gauteng</b>: Moreleta Nature Reserve, 10 November 2016, <i>Jaca & Mkhize 858</i> (PRE); Suikerbosrand, Heidelbergkloof, 16 October 1971, <i>Bredenkamp 123</i> (PRE). <b>Mpumalanga</b>: 4 km out of Sabie on road to Graskop, 19 December 1979, <i>Henderson & Gaum 18</i> (PRE); 1 km van Graskop na Sabie, 28 October 1981, <i>Stirton 9797</i> (PRE); 1 km van Graskop na Sabie, 29 October 1981, <i>Stirton 9800</i>, <i>9859</i>, <i>9861</i>, <i>9863</i> & <i>9866</i> (PRE); Sabie to Bridal Veil Falls, 6 November 1996, <i>Henderson 1191</i> (PRE); Long Tom Pas, near Mabulwa Estate, 30 October 2000, <i>Burrows & Burrows 7067</i> (PRE); Lydenburg, Dullstroom, 20 November 1977, <i>Stirton 7255</i> (PRE); Duiwelskloof, Weltevreden, 30 October 1959, <i>Scheepers 750</i> (PRE); Wonderkloof, Sudwala, Rosehaugh Road, 4 November 1996, <i>Henderson 1183</i> (PRE). <b>Free State</b>: R 711 from Clarens to Fouriesburg, 21 November 2012, <i>Jaca 484</i> & <i>Netshianane AN 22</i> (PRE); Clarens, along the R 711, 2 February 2018, <i>Beek 2018.01</i> (L). <b>KwaZulu-Natal</b>: Road from Vryheid to Louwsburg, 3.2 km before the exit to Louwsburg, south side of the road, 14 February 2018, <i>Beek 2018.08</i> (L); Pietermaritzburg, November1945, <i>Smith s.n</i>. (PRE); Allerton Laboratory, Chase Valley, 26 October 1938, <i>Connell 21</i> (PRE); Himeville, 20 November 1961, <i>Marr 26</i> (PRE).</p> <p> — <b>SWAZILAND.</b> Mololotja Nature Reserve Swaziland, 14 November 1988, <i>Braun 473</i> (PRE); Along the MR1 south of Piggs Peak, just south of Hawane Christian Life Community Church, 12 February 2018, <i>Beek 2018.06</i> (L).</p>Published as part of <i>Beek, Abraham Van De, 2021, Rubi Capenses: a further contribution to the knowledge of the genus Rubus (Rosaceae) in South Africa, pp. 1-71 in Phytotaxa 515 (1)</i> on page 50, DOI: 10.11646/phytotaxa.515.1.1, <a href="http://zenodo.org/record/8061143">http://zenodo.org/record/8061143</a>
Chemical analysis and quality control of Ginkgo biloba leaves, extracts, and phytopharmaceuticals
No full textThe chemical analysis and quality control of Ginkgo leaves, extracts, phytopharmaceuticals and some herbal supplements is comprehensively reviewed. The review is an update of a similar, earlier review in this journal [T.A. van Beek, J. Chromatogr. A 967 (2002) 21¿55]. Since 2001 over 3000 papers on Ginkgo biloba have appeared, and about 400 of them pertain to chemical analysis in a broad sense and are cited herein. The more important ones are discussed and, where relevant, compared with the best methods published prior to 2002. In the same period over 2500 patents were filed on Ginkgo and the very few related to analysis are mentioned as well. Important constituents include terpene trilactones, i.e. ginkgolide A, B, C, J and bilobalide, flavonol glycosides, biflavones, proanthocyanidins, alkylphenols, simple phenolic acids, 6-hydroxykynurenic acid, 4-O-methylpyridoxine and polyprenols. In the most common so-called ¿standardised¿ Ginkgo extracts and phytopharmaceuticals several of these classes are no longer present. About 130 new papers deal with the analysis of the terpene trilactones. They are mostly extracted with methanol or water or mixtures thereof. Supercritical fluid extraction and pressurised water extraction are also possible. Sample clean-up is mostly by liquid¿liquid extraction with ethyl acetate although no sample clean-up at all in combination with LC/MS/MS is gaining in importance. Separation and detection can be routinely carried out by RP-HPLC with ELSD, RI or MS, or by GC/FID or GC/MS after silylation. Hydrolysis followed by LC/MS allows the simultaneous analysis of terpene trilactones and flavonol aglycones. No quantitative procedure for all major flavonol glycosides has yet been published because they are not commercially available. The quantitation of a few available glycosides has been carried out but does not serve a real purpose. After acidic hydrolysis to the aglycones quercetin, kaempferol and isorhamnetin and separation by HPLC, quantitation is straightforward and yields by recalculation an estimation of the original total flavonol glycoside content. A profile of the genuine flavonol glycosides can detect poor storage or adulteration. Although the toxicity of Ginkgo alkylphenols upon oral administration has never been undoubtedly proven, most suppliers limit their content in extracts to 5 ppm and dozens of papers on their analysis were published. One procedure in which a methanolic extract is directly injected on a C8 HPLC column appears superior in terms of sensitivity
Reformed and Reforming: John Owen on the Kingdom of Christ
No full textBeek, A. van de [Promotor]Vries, P. de [Copromotor
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