209,711 research outputs found
Interview of Sayed Z. El-Sayed by Brian Shoemaker
No full textDr. Hussein Fausi, pp. 2
Professor Abdel Fatah Mohammed, pp. 2
Dr. Richard Van Cleef, pp. 3
Dr. Richard Flemming, pp. 3
Haupt ______, pp. 3
Ravel _______, pp. 3
Shepard ______, pp. 3
Claude du Bear, pp. 3
Walter Monk, pp. 3
Peter Ray, pp. 3
Captain Luis R. Capurro, pp. 6-7
Byunig Don Lee, pp. 8, 22
Dr. Martin Johnson, pp. 9
Captain Canepa, pp. 9-10
Larry Gould, pp. 10
______Zumberg, pp. 10
Lee Washbrun, pp. 10
George Llano, pp. 10, 15, 23-24, 30
Professor Mosby, pp. 12
Richard Thornton, pp. 13
_______Allsion McQueeny, pp. 15
Dr. Morita, pp. 15, 23
Claude Zumell, pp. 16
Holm Henson, pp. 16, 23
Larry Weber, pp. 19
_______Filchner, pp. 22
_______Shackelton, pp. 22
Mary Alice ________, pp. 22-23
George Knox, pp. 28
Dr. Numoto, pp. 29
Lou de Galle, pp. 29
Dick Laws, pp. 29, 37, 42, 64, 66
Joe Farnham, pp. 34, 63
Carol ________, pp. 35
Todd ________, pp. 40
Lubimora ______, pp. 40
Professor Bogdanor, pp. 41
__________ Kryzechevski, pp. 42
Barry Heywood, pp. 42, 65
David Drury, pp. 43
Martin Johnson, pp. 46
Carl Stegan, pp. 54
Sherwood Roland, pp. 55
Mario Mornina, pp. 55
Paul Ramsey, pp. 55-56
Bob Stephenson, pp. 60
Paul Skelly Powers, pp. 60
Charlie Inge, pp. 60
_________ Hovis, pp. 60
Emil Anderson, pp. 61
Admiral Bill Ramsey, pp. 62
Dean Stockwell, pp. 62
Bernard Stonehouse, pp. 64
Bob Abel, pp. 67Dr. El-Sayed was born in Alexandria, Egypt. After secondary school, he went to the University of Alexandria for his B.S. (1949) in Oceanography. After his M.S., he went to the Scripps Institute of Oceanography on a Fulbright Fellowship. He received his PhD from the University of Washington. As professor emeritus at Texas A & M, he directs a project with the Cooperative Marine Research Program in the Middle East. A friend asked him to work on a biological project on Drake Passage, Antarctica.
He worked for several years on vessels from Argentina and was later assigned to a ship for the study of krill. The science team included specialists interested in different aspects of the ecosystem. This was the first of many trips, including those on the Atlantic Ocean, Pacific Ocean, and Indian Ocean. He wrote the book “The Historical Perspective of the Antarctic Marine Research.” This book addresses the studies on the productivity of krill, in addition to phytoplankton and how solar radiation, nutrients, and the depletion of the ozone affected the marine ecosystem. The UVB radiation had a deleterious effect on the survival of the phytoplankton and nanoplankton.
Dr. El-Sayed describes his associations with SCAR, BIMASS, SCORE, and other research organizations. He summarizes the phasing out of CFCs production. Because some phytoplankton are inhibited by solar radiation, the maximum concentration of chlorophyll is between 10 and 20 meters. As a member of the Nimbus Experimental Team, Dr. El-Sayed used the coastal zone color scanner to study the krill ecosystem.
Major Topics
The University of Alexandria
The Scripps Institute of Oceanography
The University of Washington
Texas A & M University
Cooperative Marine Research Program in the Middle East
Drake Passage in Antarctica
Phytoplankton and nanoplankton on the Filchner Ice Shelf
Water currents in the Weddell Sea
Changes in the krill population
The formation of SCAR’s Marine Committee
The Antarctic marine ecosystem
Establishment of the first two International BIMASS experiments
The use of satellite images to study marine ecologyFunded by a grant from the National Science Foundation
Brevipalpus olearius Sayed 1950
No full text<i>Brevipalpus olearius</i> Sayed, 1950. <p>(Fig. 4 B).</p> <p> <i>Brevipalpus olearius</i> Sayed, 1950: 1018.</p> <p> <b>Material examined</b>: 2 females ex <i>Olea europea</i> L.(Oleaceae) <b>EGYPT:</b> Qalubia province, Moshtohor village, 30 <b>◦</b> 21'18"N, 31 <b>◦</b> 13'30"E, 19 May 2012, coll. A.M. Halawa; 2 females ex <i>Olea europea</i> L.(Oleaceae) <b>EGYPT</b>: Giza province, Dokki, 30 <b>◦</b> 02'6"N, 31 <b>◦</b> 13'30"E, 17 October 2012, coll. A.M. Halawa.; 1 female ex <i>Olea europea</i> L.(Oleaceae) <b>EGYPT</b>: El- Sharkia province, Enshas, 30 <b>◦</b> 23'6"N, 31 <b>◦</b> 27'18"E, 13 June, coll. M.M. Fawzy.</p> <p> <b>Remark.</b> The holotype of <i>Brevipalpus olearius</i> was found on <i>Olea europea</i> L in Egypt by Sayed (1950). Specimens collected in this study were compared with the holotype deposited at Plant Protection Research Institute (PPRI), Agricultural Research Center (ARC), Egypt.</p>Published as part of <i>Halawa, Alaa M. & Fawzy, Magdy M., 2014, A new species of Brevipalpus Donnadieu (Acari: Tenuipalpidae) and key to the Egyptian species, pp. 87-95 in Zootaxa 3755 (1)</i> on page 92, DOI: 10.11646/zootaxa.3755.1.4, <a href="http://zenodo.org/record/285474">http://zenodo.org/record/285474</a>
Restaurant review of The Afghan Restaurant in Falmouth, owned by M. Hashim Sayed
No full textRestaurant review of The Afghan Restaurant in Falmouth, owned by M. Hashim Sayed
Anaerobic treatment of slaughterhouse wastewater using the UASB process
No full textEffluents from the slaughterhouses, meat and poultry industries are heavily polluted and contain a high concentration of biodegradable organic materials. Therefore, the pollution capacity of these industries is high. Most of these industries discharge their effluents to a sewer or a watercourse.In order to comply with water pollution control standards and to reduce costs on sewer surcharges, these industries have to apply an adequate treatment of their effluents.Physical and chemical treatment methods as well as the conventional biological treatment processes are frequently applied in the treatment of these effluents. A combination of the methods are required where the effluent is to be discharged to surface waters, since no single treatment method will provide sufficient effluent.In the last decade, the high rate anaerobic wastewater treatment systems have become a good alternative for conventional aerobic as well as anaerobic biological treatment methods. The high rate anaerobic treatment systems were initially developed for the treatment of highly soluble low and medium strength wastewaters. These systems provided only a partial treatment of complex wastewaters containing a high fraction of suspended solids such as slaughterhouse wastewater.Investigations have shifted towards the application of high rate systems like the upflow anaerobic sludge blanket (UASB) for the complete treatment of agro-industrial wastewaters which are more difficult to handle, because they contain relatively high concentrations of suspended solids, i.e. complex wastewaters.Presently, the UASB system is the most widely applied high rate anaerobic system for complete treatment of such complex wastes.This thesis focuses on the question whether, and under which operationa conditions and environmental circumstances a one stage UASB mesophilic anaerobic treatment system is suitable for a complete treatment of slaughterhouse wastewater in practice.The feasibility of using the upflow flocculent anaerobic sludge blanket (UASB) process for a one stage anaerobic treatment of unsettled complex slaughterhouse wastewater, which contains approximately 50% of coarse insoluble COD, was investigated (Chapter 2). The continuous experiments were performed in a 25.3 m 3UASB pilot-plant which was operated under semi-continuous conditions, viz. with a varying organic load over day and nighttime (i.e. high organic load during the daytime and with low organic load at night) and with weekend feed interruptions. The UASB pilot-plant was operated at a temperature of 30° C. In order to assess the feasibility of the process under conditions of lower temperatures the temperature was reduced to 20°C, 20 weeks after the start-up of the reactor.The data indicated that the system can satisfactorily handle organic loads up to 3.5 kg COD m -3day -1at a liquid retention time of 8 h at temperatures as low as 20°C. Temporary shock loads up to 7.5 kg COD m -3day -1during the day time at a liquid retention time of 5 h were accommodated satisfactorily provided such a shock load was followed by a period of low loading, e.g. at night.A significant discrepancy was found between the treatment efficiency in terms of COD reduction and to the lower calculated percentage of supplied COD total converted into methane-COD. This difference indicated that a significant portion of the achieved COD reduction was due to the accumulation of non- or slowly biodegradable substrate ingredients in the reactor. No differentiations could be made between the different types of substrate ingredients that accummulated in the reactor because the accumulated sludge was not characterized. However, a part of the accumulated substrate was converted to CH 4 in periods of feed interruptions.In Chapter 3 the feasibility of the upflow granular anaerobic sludge blanket process for a one-stage anaerobic treatment of slaughterhouse wastewater was investigated. The experiments were performed under semi-continuous operational conditions viz. continuous feeding at a constant organic load (24 h day) during the working days but with weekend feed interruptions, and process temperatures of 30°C and 20°C. Under a stable operation of the system, i.e. at a maximum COD reduction and a high conversion of COD into methane, the optimal loading rates that could be applied were 11 kg COD m -3day -1and 7 kg COD m -3day -1at 30°C and at 20°C respectively.The system was less effective in the removal of coarse suspended solids, compared to the removal of the colloidal and soluble fractions from the slaughterhouse wastewater.The data obtained in these investigations indicate that imposed prolonged loadings exceed the optimal loading rates, lead to deterioration of the specific methanogenic activity of the sludge, due to the accumulation of colloidal and soluble fractions of the wastewater in the sludge bed. Therefore, it was concluded that the system stability strongly depends on the processes involved in the removal of the colloidal and soluble compounds from the wastewater and their conversion into methane. As the predominant - non-biological-mechanisms underlying the elimination of these wastewaters pollutants were considered the entrapment and the adsorption mechanisms. The effect of these mechanisms on the rate of the liquefaction of the accumulated substrate - which is the required first step in their conversion into methane - were discussed.The different pollutant fractions of the wastewater, viz. the coarse suspended solids, the colloidal and the soluble compounds affect the performance of the UASB reactors because of the different mechanisms involved in the removal of these substrate ingredients and their subsequent conversion into methane. Therefore, these mechanisms were investigated in more detail. The results of these investigations are presented in Chapter 4. The experiments were performed in a one-stage flocculent sludge UASB-reactor under continuous operational conditions viz. continuous feeding at a constant organic load during 24 h a day and 7 days a week.The COD removal efficiency of the UASB reactor exceeded the COD removal efficiency as expected from the observed CH 4 production, indicating once again that non-biological mechanisms are involved. Two different non-biological mechanisms were distinguished in the removal of substrate ingredients from the wastewater. The entrapment mechanism prevailed in the elimination of coarse suspended solids, while mainly adsorption mechanisms are involved in the removal of colloidal and the soluble fractions of the wastewater.A continued accumulation of substrate ingredients in the reactor ultimately will become detrimental for the stability of the anaerobic treatment process, as it leads to sludge flotation and consequently could result in a complete loss of the active biomass from the reactor.After having demonstrated the principle feasibility of the upflow anaerobic sludge blanket (UASB) process for a one-stage anaerobic treatment of the slaughterhouse wastewater, we decided to assess the maximum possible extent of anaerobic degradation of the soluble, colloidal and coarse suspended solids fractions of the slaughterhouse wastewater (Chapter 5). In this way we intended to get a better insight in the real limitations of the system. All the experiments were performed at process temperatures of 30°C and 20°C, using membrane filtered wastewater (wastewater mf ), paper filtered wastewater (wastewater pf ) and total wastewater. The experiments were performed in a recirculated batch digester system with granular sludge. The experiments with the coarse suspended solids separated from the wastewater were performed with granular sludge as well as with flocculent sludge using conventional batch-fed stirred digesters. The maximum biodegrability percentages (i.e. conversion into methane) found at 30°C were 75% for wastewater mf , 61% for wastewater pf and 67% for wastewater total while at 20°C these values were 72%, 49% and 51% respectively. The maximum biodegrability of the coarse suspended solids fraction of the waste amounts to 50% at 30°C and 45% at 20°C.The mechanisms involved in the removal of the soluble and colloidal fractions of the slaughterhouse wastewater were thoroughly studied and elucidated. The data obtained in these experiments indicate that the prevailing mechanism in the removal of the soluble but especially also the colloidal fraction of the wastewater is an adsorption mechanism. The relatively high degree of adsorption of the colloidal fraction of the wastewater to the surface of the sludge, in combination with its high fat content, will deteriorate the specific methanogenic activity of the sludge. The adsorption of the colloidal materials will ultimately result in an enclosure of the granular sludge bacterial matter with a film of increasing thickness, and perhaps also density, which increasingly will hamper the supply of substrate to the bacteria present in the grains. The deterioration effect of fats towards the methanogenic activity of the sludge was explained on the basis of the inhibitory effect of the long-chain fatty acids of the neutral fats.As the extent of adsorption is very similar at lower and higher temperatures, but the rate of liquefaction of adsorbed compounds drops significantly at decreasing temperatures, it will be evident that the process can withstand considerably lower loading rates at 20°C as compared to 30°C.Therefore, it is concluded that the rate of liquefaction of the adsorbed insoluble colloidal fraction of the wastewater is the controlling factor with respect to loading potentials of the process and consequently that the temperature is the factor of predominant importance
Anaerobic treatment of slaughterhouse wastewater using the UASB process
No full textEffluents from the slaughterhouses, meat and poultry industries are heavily polluted and contain a high concentration of biodegradable organic materials. Therefore, the pollution capacity of these industries is high. Most of these industries discharge their effluents to a sewer or a watercourse.In order to comply with water pollution control standards and to reduce costs on sewer surcharges, these industries have to apply an adequate treatment of their effluents.Physical and chemical treatment methods as well as the conventional biological treatment processes are frequently applied in the treatment of these effluents. A combination of the methods are required where the effluent is to be discharged to surface waters, since no single treatment method will provide sufficient effluent.In the last decade, the high rate anaerobic wastewater treatment systems have become a good alternative for conventional aerobic as well as anaerobic biological treatment methods. The high rate anaerobic treatment systems were initially developed for the treatment of highly soluble low and medium strength wastewaters. These systems provided only a partial treatment of complex wastewaters containing a high fraction of suspended solids such as slaughterhouse wastewater.Investigations have shifted towards the application of high rate systems like the upflow anaerobic sludge blanket (UASB) for the complete treatment of agro-industrial wastewaters which are more difficult to handle, because they contain relatively high concentrations of suspended solids, i.e. complex wastewaters.Presently, the UASB system is the most widely applied high rate anaerobic system for complete treatment of such complex wastes.This thesis focuses on the question whether, and under which operationa conditions and environmental circumstances a one stage UASB mesophilic anaerobic treatment system is suitable for a complete treatment of slaughterhouse wastewater in practice.The feasibility of using the upflow flocculent anaerobic sludge blanket (UASB) process for a one stage anaerobic treatment of unsettled complex slaughterhouse wastewater, which contains approximately 50% of coarse insoluble COD, was investigated (Chapter 2). The continuous experiments were performed in a 25.3 m 3UASB pilot-plant which was operated under semi-continuous conditions, viz. with a varying organic load over day and nighttime (i.e. high organic load during the daytime and with low organic load at night) and with weekend feed interruptions. The UASB pilot-plant was operated at a temperature of 30° C. In order to assess the feasibility of the process under conditions of lower temperatures the temperature was reduced to 20°C, 20 weeks after the start-up of the reactor.The data indicated that the system can satisfactorily handle organic loads up to 3.5 kg COD m -3day -1at a liquid retention time of 8 h at temperatures as low as 20°C. Temporary shock loads up to 7.5 kg COD m -3day -1during the day time at a liquid retention time of 5 h were accommodated satisfactorily provided such a shock load was followed by a period of low loading, e.g. at night.A significant discrepancy was found between the treatment efficiency in terms of COD reduction and to the lower calculated percentage of supplied COD total converted into methane-COD. This difference indicated that a significant portion of the achieved COD reduction was due to the accumulation of non- or slowly biodegradable substrate ingredients in the reactor. No differentiations could be made between the different types of substrate ingredients that accummulated in the reactor because the accumulated sludge was not characterized. However, a part of the accumulated substrate was converted to CH 4 in periods of feed interruptions.In Chapter 3 the feasibility of the upflow granular anaerobic sludge blanket process for a one-stage anaerobic treatment of slaughterhouse wastewater was investigated. The experiments were performed under semi-continuous operational conditions viz. continuous feeding at a constant organic load (24 h day) during the working days but with weekend feed interruptions, and process temperatures of 30°C and 20°C. Under a stable operation of the system, i.e. at a maximum COD reduction and a high conversion of COD into methane, the optimal loading rates that could be applied were 11 kg COD m -3day -1and 7 kg COD m -3day -1at 30°C and at 20°C respectively.The system was less effective in the removal of coarse suspended solids, compared to the removal of the colloidal and soluble fractions from the slaughterhouse wastewater.The data obtained in these investigations indicate that imposed prolonged loadings exceed the optimal loading rates, lead to deterioration of the specific methanogenic activity of the sludge, due to the accumulation of colloidal and soluble fractions of the wastewater in the sludge bed. Therefore, it was concluded that the system stability strongly depends on the processes involved in the removal of the colloidal and soluble compounds from the wastewater and their conversion into methane. As the predominant - non-biological-mechanisms underlying the elimination of these wastewaters pollutants were considered the entrapment and the adsorption mechanisms. The effect of these mechanisms on the rate of the liquefaction of the accumulated substrate - which is the required first step in their conversion into methane - were discussed.The different pollutant fractions of the wastewater, viz. the coarse suspended solids, the colloidal and the soluble compounds affect the performance of the UASB reactors because of the different mechanisms involved in the removal of these substrate ingredients and their subsequent conversion into methane. Therefore, these mechanisms were investigated in more detail. The results of these investigations are presented in Chapter 4. The experiments were performed in a one-stage flocculent sludge UASB-reactor under continuous operational conditions viz. continuous feeding at a constant organic load during 24 h a day and 7 days a week.The COD removal efficiency of the UASB reactor exceeded the COD removal efficiency as expected from the observed CH 4 production, indicating once again that non-biological mechanisms are involved. Two different non-biological mechanisms were distinguished in the removal of substrate ingredients from the wastewater. The entrapment mechanism prevailed in the elimination of coarse suspended solids, while mainly adsorption mechanisms are involved in the removal of colloidal and the soluble fractions of the wastewater.A continued accumulation of substrate ingredients in the reactor ultimately will become detrimental for the stability of the anaerobic treatment process, as it leads to sludge flotation and consequently could result in a complete loss of the active biomass from the reactor.After having demonstrated the principle feasibility of the upflow anaerobic sludge blanket (UASB) process for a one-stage anaerobic treatment of the slaughterhouse wastewater, we decided to assess the maximum possible extent of anaerobic degradation of the soluble, colloidal and coarse suspended solids fractions of the slaughterhouse wastewater (Chapter 5). In this way we intended to get a better insight in the real limitations of the system. All the experiments were performed at process temperatures of 30°C and 20°C, using membrane filtered wastewater (wastewater mf ), paper filtered wastewater (wastewater pf ) and total wastewater. The experiments were performed in a recirculated batch digester system with granular sludge. The experiments with the coarse suspended solids separated from the wastewater were performed with granular sludge as well as with flocculent sludge using conventional batch-fed stirred digesters. The maximum biodegrability percentages (i.e. conversion into methane) found at 30°C were 75% for wastewater mf , 61% for wastewater pf and 67% for wastewater total while at 20°C these values were 72%, 49% and 51% respectively. The maximum biodegrability of the coarse suspended solids fraction of the waste amounts to 50% at 30°C and 45% at 20°C.The mechanisms involved in the removal of the soluble and colloidal fractions of the slaughterhouse wastewater were thoroughly studied and elucidated. The data obtained in these experiments indicate that the prevailing mechanism in the removal of the soluble but especially also the colloidal fraction of the wastewater is an adsorption mechanism. The relatively high degree of adsorption of the colloidal fraction of the wastewater to the surface of the sludge, in combination with its high fat content, will deteriorate the specific methanogenic activity of the sludge. The adsorption of the colloidal materials will ultimately result in an enclosure of the granular sludge bacterial matter with a film of increasing thickness, and perhaps also density, which increasingly will hamper the supply of substrate to the bacteria present in the grains. The deterioration effect of fats towards the methanogenic activity of the sludge was explained on the basis of the inhibitory effect of the long-chain fatty acids of the neutral fats.As the extent of adsorption is very similar at lower and higher temperatures, but the rate of liquefaction of adsorbed compounds drops significantly at decreasing temperatures, it will be evident that the process can withstand considerably lower loading rates at 20°C as compared to 30°C.Therefore, it is concluded that the rate of liquefaction of the adsorbed insoluble colloidal fraction of the wastewater is the controlling factor with respect to loading potentials of the process and consequently that the temperature is the factor of predominant importance
On Functions Preserving Convergence of Series in Fuzzy n-Normed Spaces
No full textThe purpose of this paper is to introduce finite convergence sequences and
functions preserving convergence of series in fuzzy n-normed spaces
Terpnacarus zaheri Momen, Sayed & Nasr, 2004, n. sp.
No full textTerpnacarus zaheri n. sp. (Figs 1–7) ADULT FEMALE. Dimensions: length of body (including gnathosoma) 333–346, length of body (excluding gnathosoma) 301–306, breadth of body 180–189. Dorsum (Figs 1 & 2). The prodorsum bears 6 pairs of setae (Fig. 2). Setae le robust, distinctly logner than setae xp and in, are of equal length of setae xa (35–38), setae ro (14– 16), which situated on the naso, are shorter than setae in (18–21). Setae xp are very small and pectinate. The naso is large and bears a lenslike eye ventrally. Sensillae bo are filamentous and ciliate (56–61 long). The central part of the prodorsum has longitudinal smooth striae. The hysterosoma (Fig. 1) bears 36 pairs of plumose setae which are situated in 9 transverse rows. Striae on the dorsum of the hysterosoma are smooth. Venter: The genital opening (Fig. 6) is relatively large and the covers are clearly defined. Each cover bears 14 large and pilose setae, arranged in two rows. Three pairs of genital papillae as well as 3 pairs of long, nude internal setae are present. Six pairs of paragenital setae are present. The anal pore is surrounded by 6 pairs of anal setae and 5 pairs of paraanals. Gnathosoma (Figs. 3–5): The chelicerae (Fig. 3) are bulky, chelatedentate and bear 2 setae dorsally. The hypognathum (Fig. 4) bears 6 pairs of setae, the anterior pair, small and nude, while the second pair are robust and relatively blunt distally. The rutella are well developed and each terminates in a sharp bladelike edge. The palpal tarsus (Fig. 5) bears 11 plumose setae, one smooth and short seta, one obtuse solenidion and terminally one yataganshaped solenidion. Legs: Leg setal patterns (formula indicates setation from tarsus to trochanter with solenidion in parentheses). Tarsus I (Fig. 7) bears one long, slender solenidion and one famulus, while tibia I bears 2 slender solenidia and genu I bears 3 mucronate solenidia. The ambulacra of all the legs are composed of a large, rayed clawlike empodium and two true claws which are barbed and smaller than the empodium. MALE: Unknown. Etymology: The new species is named for Prof. M. Zaher, Department of Zoology, Cairo University, Egypt. Type data: Female holotype collected from debris under date palm, paratypes 5 females collected with the holotype, Egypt, 20 September 2003 by Dr. A. A. Sayed. Remarks: The genus Terpnacarus has not been recorded in Egypt before this report. The new species resembles T.carolinaensis Theron (1976) described from South Africa in having smooth and fine striation on the hysterosomal integument. It differs from the latter by having 36 pairs of hysterosomal setae opposed to 34 pairs in T. carolinensis, in having one seta on trochanter I compared to nil in T. carolinaensis. It can be separated also by having 5 pairs of para anal setae compared to 6 pairs in T. carolinaensis.Published as part of Momen, F. M., Sayed, A. A. & Nasr, A. K., 2004, A new species of the genus Terpnacarus Grandjean (Acari: Terpnacaridae) from Egypt, pp. 1-4 in Zootaxa 543 on pages 2-4, DOI: 10.5281/zenodo.15734
Effect of propolis extract (bee glue) on Tetranychus urticae Koch (Acari: Tetranychidae) under greenhouse conditions
No full textEl-sayed, Salwa M., Emam, Heba M. (2021): Effect of propolis extract (bee glue) on Tetranychus urticae Koch (Acari: Tetranychidae) under greenhouse conditions. Persian Journal of Acarology 10 (23): 299-308, DOI: 10.22073/pja.v10i3.6673
Significance of nannoplankton in primary production of the Ross Sea, Antarctica, during the 1972 Austral Summer
No full textDuring Eltanin Cruise 51 (January-February 1972), hydrographic features, phytoplankton standing crop, and primary production were determined between New Zealand and the Ross Ice Shelf. Four geographical regions with unique physical/chemical characteristics were delineated. They were the Subantarctic (SA), Antarctic Convergence (AC), Antarctic (AA), and Ross Ice Shelf (RIS) regions. Nannoplankton contribution to total phytoplankton standing crop (Chl a) and total primary production (C����� uptake) was measured by a fractionation process utilizing 10 (subscript "mean" symbol) mesh screens to separate the net and nannoplankton components. Mean phytoplankton standing crop values, integrated to 200 m, for the SA, AC, AA, and RIS regions were 23.62, 35.08, 51.41, and 96.37 mgChl a/m��, respectively. Nannoplankton accounted for 76.2%, 88.6%, and 64.9% of the standing crop in these respective areas. A significant correlation was found between the total phytoplankton standing crop in surface samples and standing crop estimates integrated over the water column. However, no correlation was found between size competition of the surface standing crop and that of the euphotic zone. Mean estimates of total phytoplankton production in the euphotic zone for the SA, AA, and RIS regions were 5.72, 6.18, and 9.97 mg/m��/hr. Nannoplankton production remained relatively constant in these regions, accounting for 90.2%, 67.0%, and 54.0% of total production in the respective regions. The increased phytoplankton standing crop and primary production observed in waters south of the Antarctic Convergence were accounted for by increases in the net plankton fraction. Average photosynthetic indexes (PI) were calculated for the total phytoplankton and the nannoplankton fraction. Significant estimates of 0.351 (P=.01) and 0.243 (P=.1) were obtained for the total PI and nannoplankton PI, respectively
Time in transit unraveling the transient behavior of M|M|m|m queues
No full textComputing an exact solution for the differential equations, with differences, system that allows the determination of the M|M|m|m system transient probabilities is a hard task. The respective complexity grows with m. The computations are extremely fastidious and the length and the fact that the expressions obtained are often approximate, and not exact, will not allow the transient probabilities behavior as time functions characterization. To overcome these problems, in this work it is analyzed how that system can supply approximate values to the M|M|m|m queue system, through matrix calculations. It is also presented an asymptotic method to solve the system that becomes possible in many cases to obtain simple approximated expressions for those probabilities using the M|M|∞ transient probabilities, very well-known and very much easier to study.info:eu-repo/semantics/acceptedVersio
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