bluuebunny/crossref_metadata_2025 huggingface dataset:
Agricultural intensification, local labor markets, and deforestation in the Philippines
Authors: SHIVELY GERALD , PAGIOLA STEFANO
Published: April 2004

This paper examines agricultural intensification and its impact on deforestation in a frontier region of the Philippines. Panel data covering the period 1994–2000 are used to study labor demand and resource reallocation in response to lowland irrigation development. Results illustrate how irrigation has led to changes in employment, incomes, and activities at the forest margin. Findings indicate that the off-farm employment opportunities created by irrigation development have helped to reduce rates of forest clearing. Although some initial employment gains have been reversed, wage-induced increases in agricultural productivity in the uplands have reduced forest pressure. Results show that lowland irrigation has had direct, indirect, and lagged effects on rates of forest clearing, and that a virtuous cycle may be at play, with irrigation leading to both poverty reduction and reduced forest pressure.
THE FIFTY YEARS' RIFT: INTELLECTUAL HISTORY AND INTERNATIONAL RELATIONS
Authors: ARMITAGE DAVID
Published: April 2004

Georg Cavallar, The Rights of Strangers: Theories of International Hospitality, the Global Community, and Political Justice since Vitoria (Aldershot: Ashgate, 2002)

Jonathan Haslam, No Virtue Like Necessity: Realist Thought in International Relations since Machiavelli (New Haven, CT: Yale University Press, 2002)

Edward Keene, Beyond the Anarchical Society: Grotius, Colonialism and Order in World Politics (Cambridge: Cambridge University Press, 2002)
THE DIALECTIC OF LIBERTY: LAW AND RELIGION IN ANGLO-AMERICAN CULTURE
Authors: FERGUSON ROBERT A.
Published: April 2004

The separation of church and state disguised the coordination of two very different conceptions of liberty at work in Revolutionary America, one with a religious basis in radical Protestant thought and the other with a legal basis in the secular Enlightenment. The essay combines the disciplines of law, literature, and intellectual history to investigate these contrasting formulations and their changing relationship. Cross-cultural analysis of the language of protest in both England and America gives the investigation a crucial focus. It also explains a larger movement from direct influence to refraction in Anglo-American relations.

The interdisciplinary approach is critical to understanding how the same language came to mean different things. Exegesis of the common law tradition in England and close rhetorical analysis of pulpit oratory and legal pamphleteering in Revolutionary America reveal a striking shift in the meaning of liberty as legal explanation trumped religious protest in the process of national formations. Properly understood, the paradoxical role of the American lawyer was to cap revolutionary impulses through the manipulation of the language of a bible culture. Legal positivism replaced natural law as a ruling impulse in the definition of rights, and a republic based on the right of revolution became a nation state where the test of membership would be loyalty. The long-term result has been that the citizen faces a permanent and often puzzling dichotomy best understood in dialectical terms. National identity, while secular, responds to providential invocation in the American republic of laws, and protest finds its most potent voice in religious expression.
INTELLECTUAL HISTORY AND PHILOSOPHY
Authors: KRAMER LLOYD
Published: April 2004

Donald R. Kelley, The Descent of Ideas: The History of Intellectual History (Aldershot, England/Burlington, VT: Ashgate, 2002)

Mark Bevir, The Logic of the History of Ideas (Cambridge, England/New York: Cambridge University Press, 1999)
OF SAVAGERY AND CIVIL SOCIETY: PIERRE CLASTRES AND THE TRANSFORMATION OF FRENCH POLITICAL THOUGHT
Authors: MOYN SAMUEL
Published: April 2004

This essay examines the thought of the French anthropologist Pierre Clastres (1938–1977). It situates his once-famous depiction of savage politics as a premonitory rejection of the state at the crossroads of several traditions, long- and short-term. First, Clastres's thought resonates with the primitivistic appeal by French “moralists” since the early modern period to the lifestyle of prehistoric societies; second, it casts light on the history of French anthropology in the crisis years of structuralism; and third, it reflects the revival of Friedrich Nietzsche in French thought of the era. Above all, however, the essay explains Clastres's thought as an attempt to resist and to overcome the well-known communist allegiances of postwar French intellectuals. Early in rejecting communism, Clastres owed his prominence to the 1970s popularization of the critique of “totalitarianism.” The so-called “passing of an illusion” of communism, one version of which Clastres pioneered, is often interpreted as the replacement of confusion with truth. It is more interesting, the essay suggests, to situate it in its time, as a complex achievement as defective as it was creative, if Clastres's thought is taken as an example. In closing, the essay suggests some legacies, often unintentional, Clastres left behind in French political thought of the years since his death.
GLOBAL COMMERCE AND THE QUESTION OF SOVEREIGNTY IN THE EIGHTEENTH-CENTURY PROVINCES
Authors: ROTHSCHILD EMMA
Published: April 2004

The paper is concerned with disputes over sovereignty and global commerce in the 1760s and 1770s. The eighteenth-century revolution in economic science has been identified with agricultural reforms, and with the definition of national economies. The economists of the time, including Turgot, Mirabeau, Dupont de Nemours, Baudeau and Adam Smith, were also intensely interested in the merchant sovereigns of the French, English and Dutch East India companies, and in the new colonial ventures of the post-Seven Years War period. Their writings on global commerce were sometimes extraordinarily detailed (about herrings, for example, or bye-laws) and often untheoretical. Turgot was for a brief period minister of the navy and of the colonies. The older Mirabeau described the “Spaniard” as “the true Mogul of America,” and the cod of the North Atlantic as “the inexhaustible Peru of the Dutch.” But the economists’ writings on global connections were the occasion for some of their most profound reflections on the political consequences of laissez-faire, on theories of sovereignty, on the difficulties of transporting information or instructions over very large distances, and on the changing relationships between power, law and commerce. The disputes over long-distance commerce provide an interesting insight, the paper suggests, into ways of thinking which were at the same time scientific and administrative, global and provincial.
UpGene: Application of a Web‐Based DNA Codon Optimization Algorithm
Authors: Gao Wentao , Rzewski Alexis , Sun Huijie , Robbins Paul D. , Gambotto Andrea
Published: April 2004

Although DNA codon optimization is a standard molecular biology strategy to overcome poor gene expression, to date no public software exists to facilitate this process. Among the uses of codon optimization, human immunodeficiency virus (HIV) vaccine development represents one of the most difficult challenges. A key obstacle to an effective DNA‐based vaccine is the low‐level expression of HIV genes in mammalian cells, which is due primarily to the instability of HIV mRNAs resulting from AU‐rich elements and rare codon usage. In this report we describe the development of a DNA optimization algorithm integrated with a PCR primer design program to redesign specific coding sequences for maximal gene expression. Using this algorithm combination, together with PCR‐based gene assembly, we have successfully optimized gene sequences for simian immunodeficiency virus (SIV) strain mac239 structural antigenic proteins gag and env, resulting in high‐level gene expression in eukaryotic cells. Our findings demonstrate that our user‐friendly algorithm is a valuable tool for DNA‐based HIV vaccine development. Moreover, it can be used to optimize any other genes of interest and is freely available online at http://www.vectorcore.pitt.edu/upgene.html.
On‐Line Sterilization of Cheese Whey Using Ultraviolet Radiation
Authors: Mahmoud N. S. , Ghaly A. E.
Published: April 2004

The effectiveness of ultraviolet radiation for on‐line sterilization of cheese whey was investigated. The effects of flow rate and residence time on the performance of three UV reactors having different gap sizes (18, 13, and 6 mm) were studied. Six flow rates and six residence times were tested with the three UV reactors. The cheese whey used in this study had a very high turbidity (4317 NTU), very poor transmittance in the UV radiation germicidal range (∼0%), and high percentage of large solid particles (∼20% > 100 μm). Although the cheese whey physical characteristics showed low probability of sterilization using UV radiation, the study showed that UV radiation can be used on‐line to sterilize cheese whey if the proper reactor gap size and the appropriate residence time are used. There were combined effects of the flow rate and gap size. The cell removal efficiency increased with increases in residence time and decreases in the UV reactor gap size. Removal efficiency of 100% was not achieved in this study with the first UV reactor (18‐mm gap size), whereas 100% removal efficiency was achieved with the second (13‐mm gap size) and third (6‐mm gap size) UV reactors at residence times of 2.0 and 0.5 h, respectively. The microbial decay rates achieved in this study were 4.94, 7.62, and 20.9 h−1 using the first, second, and third UV reactor, respectively. Residence times of 3.3, 2.1, and 0.8 h would be required to completely destruct a microbial population of 5.95 × 106 cells/mL using the first, second, and third UV reactors, respectively. Although cheese whey sterilization using UV radiation seems to be a good alternative to pasteurization, increases in cheese whey temperature resulted in lamp fouling. If online sterilization is to be used, the fouling problem should be investigated and a maintenance scheme for the UV reactor should be developed.
Hollow‐Fiber Enzyme Reactor Operating under Nonisothermal Conditions
Authors: Diano Nadia , Grano Valentina , Rossi Sergio , Bencivenga Umberto , Portaccio Marianna , Amato Umberto , Carfora Francesca , Lepore Maria , Gaeta Francesco Saverio , Mita Damiano Gustavo
Published: April 2004

A hollow‐fiber enzyme reactor, operating under isothermal and nonisothermal conditions, was built employing a polypropylene hollow fiber onto which β‐galactosidase was immobilized. Hexamethylenediamine and glutaraldehyde were used as spacer and coupling agent, respectively. Glucose production was studied as a function of temperature, substrate concentration, and size of the transmembrane temperature gradient. The actual average temperature differences across the polypropylene fiber, to which reference was done to evaluate the effect of the nonisothermal conditions, were calculated by means of a mathematical approach, which made it possible to know, using computer simulation, the radial and axial temperature profiles inside the bioreactor and across the membrane. Percent activity increases, proportional to the size of the temperature gradients, were found when the enzyme activities under nonisothermal conditions were compared to those measured under comparable isothermal conditions. Percent reductions of the production times, proportional to the applied temperature gradients, were also calculated. The advantage of employing nonisothermal bioreactors in biotechnological industrial process was discussed.
Recovery of Lactoferrin and Lactoperoxidase from Sweet Whey Using Colloidal Gas Aphrons (CGAs) Generated from an Anionic Surfactant, AOT
Authors: Fuda Elisabeth , Jauregi Paula , Pyle D. L.
Published: April 2004

The recovery of lactoferrin and lactoperoxidase from sweet whey was studied using colloidal gas aphrons (CGAs), which are surfactant‐stabilized microbubbles (10–100 μm). CGAs are generated by intense stirring (8000 rpm for 10 min) of the anionic surfactant AOT (sodium bis‐2‐ethylhexyl sulfosuccinate). A volume of CGAs (10–30 mL) is mixed with a given volume of whey (1–10 mL), and the mixture is allowed to separate into two phases: the aphron (top) phase and the liquid (bottom) phase. Each of the phases is analyzed by SDS‐PAGE and surfactant colorimetric assay. A statistical experimental design has been developed to assess the effect of different process parameters including pH, ionic strength, the concentration of surfactant in the CGAs generating solution, the volume of CGAs and the volume of whey on separation efficiency. As expected pH, ionic strength and the volume of whey (i.e. the amount of total protein in the starting material) are the main factors influencing the partitioning of the Lf·Lp fraction into the aphron phase. Moreover, it has been demonstrated that best separation performance was achieved at pH = 4 and ionic strength = 0.1 mol/L i.e., with conditions favoring electrostatic interactions between target proteins and CGAs (recovery was 90% and the concentration of lactoferrin and lactoperoxidase in the aphron phase was 25 times higher than that in the liquid phase), whereas conditions favoring hydrophobic interactions (pH close to pI and high ionic strength) led to lower performance. However, under these conditions, as confirmed by zeta potential measurements, the adsorption of both target proteins and contaminant proteins is favored. Thus, low selectivity is achieved at all of the studied conditions. These results confirm the initial hypothesis that CGAs act as ion exchangers and that the selectivity of the process can be manipulated by changing main operating parameters such as type of surfactant, pH and ionic strength.
Assessment of the Two Helicobacter pylori α‐1,3‐Fucosyltransferase Ortholog Genes for the Large‐Scale Synthesis of LewisX Human Milk Oligosaccharides by Metabolically Engineered Escherichia coli
Authors: Dumon Claire , Samain Eric , Priem Bernard
Published: April 2004

We previously described a bacterial fermentation process for the in vivo conversion of lactose into fucosylated derivatives of lacto‐ N‐neotetraose Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)Glc (LNnT). The major product obtained was lacto‐ N‐neofucopentaose‐V Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)[Fuc(α1–3)]Glc, carrying fucose on the glucosyl residue of LNnT. Only a small amount of oligosaccharides fucosylated on N‐acetylglucosaminyl residues and thus carrying the LewisX group (LeX) was also produced. We report here a fermentation process for the large‐scale production of LeX oligosaccharides. The two fucosyltransferase genes futA and futB of Helicobacter pylori (strain 26695) were compared in order to optimize fucosylation in vivo. futA was found to provide the best activity on the LNnT acceptor, whereas futB expressed a better LeX activity in vitro. Both genes were expressed to produce oligosaccharides in engineered Escherichia coli ( E. coli) cells. The fucosylation pattern of the recombinant oligosaccharides was closely correlated with the specificity observed in vitro, FutB favoring the formation of LeX carrying oligosaccharides. Lacto‐ N‐neodifucohexaose‐II Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–3)Gal(β1–4)[Fuc(α1–3)]Glc represented 70% of the total oligosaccharide amount of futA‐on‐driven fermentation and was produced at a concentration of 1.7 g/L. Fermentation driven by futBled to equal amounts of both lacto‐ N‐neofucopentaose‐V and lacto‐ N‐neofucopentaose‐II Gal(β1–4)[Fuc(α1–3)]GlcNAc(β1–3)Gal(β1–4)Glc, produced at 280 and 260 mg/L, respectively. Unexpectedly, a noticeable proportion (0.5 g/L) of the human milk oligosaccharide 3‐fucosyllactose Gal(β1–4)[Fuc(α1–3)]Glc was produced in futA‐on‐driven fermentation, underlining the activity of fucosyltransferase FutA in E. coli and leading to a reassessment of its activity on lactose. All oligosaccharides produced by the products of both fut genes were natural compounds of human milk.
Hyperosmotic Stress in Murine Hybridoma Cells: Effects on Antibody Transcription, Translation, Posttranslational Processing, and the Cell Cycle
Authors: Sun Zhe , Zhou Rui , Liang Shuyan , McNeeley Kathleen M. , Sharfstein Susan T.
Published: April 2004

Mechanisms for increased antibody production in batch cultures of murine hybridoma cells in response to hyperosmotic stress were investigated. The rates of immunoglobulin transcription and protein translation and posttranslational processing were determined in control and hyperosmotic cultures. Changes in immunoglobulin transcription played a minor role in the increase in antibody production in response to hyperosmotic stress. In contrast, protein translation increased substantially in response to osmotic stress. However, the antibody translation rate remained relatively constant after correcting for the overall increase in protein translation. Cell size and intracellular antibody pool also increased in response to hyperosmolarity. The intracellular antibody pool increased proportionately with the increase in cell size, indicating that hyperosmotic cultures do not selectively increase their intracellular antibody population. Changes in cell cycle distribution in response to osmotic stress and the relationship between the cell cycle and antibody production were also evaluated. Hyperosmotic stress altered the cell cycle distribution, increasing the fraction of the cells in S‐phase. However, this change was uncorrelated with the increase in antibody production rate. Immunoglobulin degradation was relatively low (∼15%) and remained largely unchanged in response to hyperosmotic stress. There was no apparent increase in immunoglobulin stability as a result of osmotic stress. Antibody secretion rates increased approximately 50% in response to osmotic stress, with a commensurate increase in the antibody assembly rate. The rate of transit through the entire posttranslational processing apparatus increased, particularly for immunoglobulin light chains. The levels of endoplasmic reticulum chaperones did not increase as a fraction of the total cellular protein but were increased on a per cell basis as the result of an increase in total cellular protein. A difference in the interactions between the immunoglobulin heavy chains and BiP/GRP78 was observed in response to hyperosmotic conditions. This change in interaction may be correlated with the decrease in transit time through the posttranslational pathways. The increase in the posttranslational processing rate appears to be commensurate with the increase in antibody production in response to hyperosmotic stress.
Protein Partitioning in Aqueous Two‐Phase Systems Composed of a pH‐Responsive Copolymer and Poly(ethylene glycol)
Authors: Waziri Saidu M. , Abu‐Sharkh Basel F. , Ali Sk Asrof
Published: April 2004

The effect of pH and salt concentration on the partitioning behavior of bovine serum albumin (BSA) and cytochrome c in an aqueous two‐phase polymer system containing a novel pH‐responsive copolymer that mimics the structure of proteins and poly(ethylene glycol) (PEG) was investigated. The two‐phase system has low viscosity. Depending on pH and salt concentration, the cytochrome c was found to preferentially partition into the pH‐responsive copolymer‐rich (bottom) phase under all conditions of pH and salt concentrations considered in the study. This was caused by the attraction between the positively charged protein and negatively charged copolymer. BSA partitioning showed a more complex behavior and partitioned either to the PEG phase or copolymer phase depending on the pH and ionic strength. Extremely high partitioning levels (partition coefficient of 0.004) and very high separation ratios of the two proteins (up to 48) were recorded in the new systems. This was attributed to strong electrostatic interactions between the proteins and the charged copolymer.
Modeling the Kinetics of the Pectin Methylesterase Catalyzed De‐esterfication of Pectin in Frozen Systems
Authors: Terefe Netsanet Shiferaw , Nhan Minh Tri , Vallejo David , Van Loey Ann , Hendrickx Marc
Published: April 2004

The applicability of the William, Landel, and Ferry (WLF) equation with a modification to take into account the effect of melt‐dilution and an empirical log‐logistic equation were evaluated to model the kinetics of diffusion‐controlled reactions in frozen systems. Kinetic data for the pectin methylesterase catalyzed hydrolysis of pectin in four model systems with different glass transition temperatures: sucrose, maltodextrin (DE = 16.5–19.5), carboxymethylcellulose (CMC) and fructose in a temperature range of –24 to 0 °C were used. The modified WLF equation was evaluated with a concentration‐dependent glass transition temperature ( Tg) as well as the glass transition temperature of the maximally freeze‐concentrated matrix ( Tg′) as reference temperatures. The equation with temperature‐dependent Tg described the reaction kinetics reasonably well in all the model systems studied. However the kinetics was better described by a linear relationship between log( V0/ V0ref) and ( T – Tref) in all cases except CMC. The log‐logistic equation also described the kinetics reasonably well. The effect of melt‐dilution on reactant concentration was found to be minimal in all cases.
Real‐Time Intracellular Transport of Gene Nanocarriers Studied by Multiple Particle Tracking
Authors: Suh Junghae , Wirtz Denis , Hanes Justin
Published: April 2004

We used real‐time multiple particle tracking to quantitatively characterize the type and rates of transport of gene nanocarriers within live cells. The heterogeneous cytoplasmic transport of polyethylenimine (PEI)/DNA gene carriers was quantified by tracking their mean‐square displacements over time and classified into active and nonactive transport populations on the basis of their effective diffusivities versus time. Nonactive gene carriers frequently displayed hop‐diffusion trajectories, suggesting a porous cytoplasmic network of flexible biopolymers or sequential attachment and detachment events. Microtubule‐dependent active transport of gene carriers resulted in an effective diffusivity 30‐fold greater than that of nonactive carriers (at a time scale of 3 s). Compared to nonactive carriers in control cells with intact microtubules, microtubule depolymerization enhanced short‐range motion of gene carriers but resulted in similar long‐range transport. Multiple particle tracking characterizes gene carrier transport in complex biological environments and, therefore, may be a useful tool in quantifying rate‐limiting steps in gene delivery within cells and other biological media.
Separation of Protein Charge Variants by Ultrafiltration
Authors: Ebersold Mareia Frost , Zydney Andrew L.
Published: April 2004

The removal of product variants that form during downstream processing remains a challenge in the purification of recombinant therapeutic proteins. We examined the feasibility of separating variants with slightly different net charge using high‐performance membrane ultrafiltration. A myoglobin variant was formed by reaction of the lysine ϵ‐amino group with succinic anhydride. Sieving data were obtained over a range of solution conditions using commercial polyethersulfone ultrafiltration membranes. Maximum selectivity of about 7‐fold was obtained at very low conductivity due to the strong electrostatic repulsion of the more negatively charged variant. Protein separations were performed by diafiltration. A two‐stage process generated solutions of the normal myoglobin (in the permeate) and the charge variant (in the retentate), both at greater than 9‐fold purification and 90% yield. These results provide the first demonstration that membrane systems can be used to separate proteins that differ by only a single charged amino acid residue.
Characteristics of Immobilized Lipase on Hydrophobic Superparamagnetic Microspheres To Catalyze Esterification
Authors: Guo Zheng , Sun Yan
Published: April 2004

A novel immobilized lipase (from Candida rugosa) on hydrophobic and superparamagnetic microspheres was prepared and used as a biocatalyst to catalyze esterification reactions in diverse solvents and reaction systems. The results showed that the immobilized lipase had over 2‐fold higher activities in higher log P value solvents. An exponential increase of lipase activity against log P of two miscible solvent mixtures was observed for the first time. Both free and immobilized lipase achieved its maximum activity at the range of water activity ( aw) 0.5–0.8 or higher. At aw 0.6, the immobilized lipase exhibited markedly higher activities in heptane and a solvent‐free system than did the native lipase. In multicompetitive reactions, the alcohol specificity of the lipase showed a strong chain‐length dependency, and the immobilized enzyme exhibited more preference for a longer‐chain alcohol, which is different from previous reports. The immobilized lipase showed higher specificities for butyric acid and the medium‐chain‐length fatty acids (C8–C12). Then, the immobilized lipase was extended to solvent‐free synthesis of glycerides from glycerol and fatty acids. Recovered by magnetic separation, the immobilized lipase exhibited good reusability in repeated batch reaction, indicating its promising feature for biotechnology application.
Purification and Characterization of a Novel Mannitol Dehydrogenase from Lactobacillus intermedius
Authors: Saha Badal C.
Published: April 2004

Mannitol 2‐dehydrogenase (MDH) catalyzes the pyridine nucleotide dependent reduction of fructose to mannitol. Lactobacillus intermedius(NRRL B‐3693), a heterofermentative lactic acid bacterium (LAB), was found to be an excellent producer of mannitol. The MDH from this bacterium was purified from the cell extract to homogeneity by DEAE Bio‐Gel column chromatography, gel filtration on Bio‐Gel A‐0.5m gel, octyl‐Sepharose hydrophobic interaction chromatography, and Bio‐Gel Hydroxyapatite HTP column chromatography. The purified enzyme (specific activity, 331 U/mg protein) was a heterotetrameric protein with a native molecular weight (MW) of about 170 000 and subunit MWs of 43 000 and 34 500. The isoelectric point of the enzyme was at pH 4.7. Both subunits had the same N‐terminal amino acid sequence. The optimum temperature for the reductive action of the purified MDH was at 35 °C with 44% activity at 50 °C and only 15% activity at 60 °C. The enzyme was optimally active at pH 5.5 with 50% activity at pH 6.5 and only 35% activity at pH 5.0 for reduction of fructose. The optimum pH for the oxidation of mannitol to fructose was 7.0. The purified enzyme was quite stable at pH 4.5–8.0 and temperature up to 35 °C. The Km and Vmax values of the enzyme for the reduction of fructose to mannitol were 20 mM and 396 μmol/min/mg protein, respectively. It did not have any reductive activity on glucose, xylose, and arabinose. The activity of the enzyme on fructose was 4.27 times greater with NADPH than NADH as cofactor. This is the first highly NADPH‐dependent MDH (EC 1.1.1.138) from a LAB. Comparative properties of the enzyme with other microbial MDHs are presented.
Purification, Immobilization, and Stabilization of a Lipase from Bacillus thermocatenulatus by Interfacial Adsorption on Hydrophobic Supports
Authors: Palomo J. M. , Segura R. L. , Fernández‐Lorente G. , Pernas M. , Rua M. L. , Guisán J. M. , Fernández‐Lafuente R.
Published: April 2004

A lipase from Bacillus thermocatenulatus (BTL2) cloned in E. coli has been purified using a very simple method: interfacial activation on a hydrophobic support followed by desorption with Triton. Only one band was detected by SDS‐PAGE. The pure enzyme was immobilized using different methodologies. BTL2 adsorbed on a hydrophobic support (octadecyl‐Sepabeads) exhibited a hyperactivation with respect to the soluble enzyme, whereas the other immobilized preparations suffered a slight decrease in the expressed activity. The soluble enzyme was very stable, but all immobilized preparations were much more stable than the soluble enzyme, the octadecyl‐Sepabeads‐BTL2 preparation being the most stable one in all conditions (high temperature or in the presence of organic cosolvents), maintaining 100% of the activity at 65 °C or 30% of dioxane and 45 °C after several days of incubation. The glyoxyl preparation, the second more stable, retained 80% of the initial activity after 2 days, respectively. The adsorption of this thermophilic lipase on octadecyl‐Sepabeads permitted an increase in the optimal temperature of the enzyme of 10 °C.
Re‐evaluation of SO2 release of the 15 June 1991 Pinatubo eruption using ultraviolet and infrared satellite sensors
Authors: Guo Song , Bluth Gregg J. S. , Rose William I. , Watson I. Matthew , Prata A. J.
Published: April 2004

In this study, ultraviolet TOMS (Total Ozone Mapping Spectrometer) satellite data for SO2 are re‐evaluated for the first 15 days following the 15 June 1991 Pinatubo eruption to reflect new data retrieval and reduction methods. Infrared satellite SO2 data from the TOVS/HIRS/2 (TIROS (Television Infrared Observation Satellite) Optical Vertical Sounder/High Resolution Infrared Radiation Sounder/2) sensor, whose data sets have a higher temporal resolution, are also analyzed for the first time for Pinatubo. Extrapolation of SO2 masses calculated from TOMS and TOVS satellite measurements 19–118 hours after the eruption suggest initial SO2 releases of 15 ± 3 Mt for TOMS and 19 ± 4 Mt for TOVS, including SO2 sequestered by ice in the early Pinatubo cloud. TOVS estimates are higher in part because of the effects of early formed sulfate. The TOMS SO2 method is not sensitive to sulfate, but can be corrected for the existence of this additional emitted sulfur. The mass of early formed sulfate in the Pinatubo cloud can be estimated with infrared remote sensing at about 4 Mt, equivalent to 3 Mt SO2. Thus the total S release by Pinatubo, calculated as SO2, is 18 ± 4 Mt based on TOMS and 19 ± 4 Mt based on TOVS. The SO2 removal from the volcanic cloud during 19–374 hours of atmospheric residence describes overall e‐folding times of 25 ± 5 days for TOMS and 23 ± 5 days for TOVS. These removal rates are faster in the first 118 hours after eruption when ice and ash catalyze the reaction, and then slow after heavy ash and ice fallout. SO2 mass increases in the volcanic cloud are observed by both TOMS and TOVS during the first 70 hours after eruption, most probably caused by the gas‐phase SO2 release from sublimating stratospheric ice‐ash‐gas mixtures. This result suggests that ice‐sequestered SO2 exists in all tropical volcanic clouds, and at least partially explains SO2 mass increases observed in other volcanic clouds in the first day or two after eruption.
High‐resolution investigation of shear wave anisotropy in D″ beneath the Cocos Plate
Authors: Rokosky J. M. , Lay T. , Garnero E. J. , Russell S. A.
Published: April 2004

Broadband shear wave signals from 16 deep South American earthquakes are used in a high‐resolution analysis of lowermost mantle structure beneath the Cocos Plate. Shear wave splitting of 162 ScS phases is generally compatible with vertical transverse isotropy (VTI) in the D″ region, with little path length or spatial dependence across the 200 × 800 km2 area sampled. Assuming a 250 km thick D″ layer, the VTI has an average value of 0.63%. ScS‐S differential travel time anomalies for the same data indicate a lateral gradient in positive D″ transverse component velocity perturbations, increasing northward. S‐wave triplication arrivals from a shear velocity discontinuity at the top of D″ show splitting similar to the ScS phases, but with smaller magnitude. Vertical resolution remains limited, but the data are consistent with VTI material being concentrated in just the upper portion or at the top and bottom of D″.
Extreme climatic events and weather regimes over the North Atlantic: When and where?
Authors: Yiou P. , Nogaj M.
Published: April 2004

Meteorological events such as severe storms, floods or droughts are often referred to as extreme events. The impact of such events on society is immense and numerous efforts have been devoted to study them. Many proxy indicators in paleoclimate variability reconstructions are sensitive to such extremes, and a careful quantification of their link to environmental parameters is indispensable. In this paper we determine the relationship between typical states of the atmospheric circulation over and around the North Atlantic, on the one hand, and extreme events, on the other. We apply a novel statistical approach to associate extremes and weather regimes. This study enables us to infer the atmospheric conditions that prevailed in the North Atlantic region during key periods of the recent past.
Transient reconnection in the cusp during strongly negative IMFBy
Authors: Khotyaintsev Y. , Buchert S. , Stasiewicz K. , Vaivads A. , Savin S. , Papitashvili V. O. , Farrugia C. J. , Popielawska B. , Tung Y.‐K.
Published: April 2004

We investigate transient magnetic reconnection (flux transfer events, FTEs) in the cusp and its ionospheric signatures. We present in situ observations by the Polar spacecraft of multiple impulsive plasma injections and related magnetopause crossings in the outer stagnant cusp of the northern hemisphere. At this time the interplanetary magnetic field (IMF) was northward, dominated by strongBy(−11 nT). Plasma injections are observed in the direction of the magnetic tension force due to the IMFByand resemble the “time of flight” energy‐latitude dispersion. Associated magnetopause crossings exhibit large magnetic field rotation (>150 degrees) and strong depression of the field magnitude (down to several percent of the value in the magnetosheath). We use conjugate observations from the Greenland magnetometer network and Sondrestrom incoherent scatter radar together with the Polar UV imager to show that the transient reconnection causes a direct response of cusp auroral brightness and ionospheric convection in the direction consistent with the IMFBypolarity. The observations, in space and on the ground, are consistent with a sequence of bulges launched by transient reconnection. We present a qualitative model of the bulge structure that is consistent with most of the Polar observations during the studied interval. Conjugate ground‐based observations provide additional evidence for transient reconnection and are consistent with the ground signature of FTEs.
Longitude variation of ion temperature in the Io plasma torus
Authors: Hill T. W. , Dessler A. J.
Published: April 2004

The Io plasma torus shows an unanticipated variation of ion temperature as a function of System III (magnetic) longitude λIII. The simple expectation for the perpendicular temperature T⊥, based on ion pick‐up in a tilted dipole magnetic field, is a double‐peaked function with two maxima and two minima per 360° of longitude, having an average value of ∼480 eV for S+ and a relatively small variation amplitude of ∼±7 eV. Instead, the observed T⊥(S+) near Io's orbit has only one maximum and one minimum, with a much smaller average value of ∼30 eV and a much larger relative variation amplitude of ∼±50%. To explain the observed temperature variation, we propose that the longitude variation of the Pedersen conductance of Jupiter's ionosphere causes the pickup speed of ions injected near Io to vary with longitude. We obtain a satisfactory fit to the observed temperature variation if we make the straightforward assumption that the ionospheric conductance varies inversely with the strength of the ionospheric magnetic field. Both the magnitude and phase of the observed T⊥ variation are consistent with this simple model. The observed parallel temperature T∥(S+) has a somewhat smaller average magnitude and a similar longitude variation, but shifted about 70° in phase toward larger λIII. The T∥ behavior is consistent with the idea that T∥ derives mainly from T⊥ through pitch‐angle scattering in the presence of the observed corotation lag of torus plasma. The 70° phase shift requires a scattering timescale of ∼50 hours, consistent with the classical timescale for ion‐ion Coulomb scattering.
Time‐variable aliasing effects of ocean tides, atmosphere, and continental water mass on monthly mean GRACE gravity field
Authors: Han Shin‐Chan , Jekeli Christopher , Shum C. K.
Published: April 2004

The Gravity Recovery and Climate Experiment (GRACE) satellite mission will provide new measurements of Earth's static and time‐variable gravity fields with monthly resolution. The temporal effects due to ocean tides and atmospheric mass redistribution are assumed known and could be removed using current models. In this study we quantify the aliasing effects on monthly mean GRACE gravity estimates due to errors in models for ocean tides and atmosphere and due to ground surface water mass variation. Our results are based on simulations of GRACE recovery of monthly gravity solution complete to degree and order 120 in the presence of the respective model errors and temporal aliasing effects. For ocean tides we find that a model error in S2 causes errors 3 times larger than the measurement noise at n < 15 in the monthly gravity solution. Errors in K1, O1, and M2 can be reduced to below the measurement noise level by monthly averaging. For the atmosphere, model errors alias the solution at the measurement noise level. The errors corrupt recovered coefficients and introduce 30% more error in the global monthly geoid estimates up to maximum degree 120. Assuming daily CDAS‐1 data for continental surface water mass redistribution, the analysis indicates that the daily soil moisture and snow depth variations with respect to their monthly mean produce a systematic error as large as the measurement noise over the continental regions.
Combined lidar‐radar remote sensing: Initial results from CRYSTAL‐FACE
Authors: McGill M. J. , Li L. , Hart W. D. , Heymsfield G. M. , Hlavka D. L. , Racette P. E. , Tian L. , Vaughan M. A. , Winker D. M.
Published: April 2004

In the near future, NASA plans to fly satellites carrying a two‐wavelength polarization lidar and a 94‐GHz cloud profiling radar in formation to provide complete global profiling of cloud and aerosol properties. The Cirrus Regional Study of Tropical Anvils and Cirrus Layers‐Florida Area Cirrus Experiment (CRYSTAL‐FACE) field campaign, conducted during July 2002, provided the first high‐altitude collocated measurements from lidar and cloud profiling radar to simulate these spaceborne sensors. The lidar and radar provide complementary measurements with varying degrees of vertical measurement overlap within cloud layers. This paper presents initial results of the combined airborne lidar‐radar measurements during CRSYTAL‐FACE. A comparison of instrument sensitivity is presented within the context of particular CRYSTAL‐FACE observations. It was determined that optically thin cirrus clouds are frequently missed by the radar but are easily profiled with the lidar. In contrast, optically thick clouds and convective cores quickly extinguish the lidar signal but are easily probed with the radar. Results are presented to quantify the portion of atmospheric features sensed independently by each instrument and the portion sensed simultaneously by the two instruments. To capture some element of varying atmospheric characteristics, two cases are analyzed, one with convective systems and one having synoptic cirrus and considerable clear air. The two cases show quite different results, primarily due to differences in cloud microphysics.
N2O emissions of a mature Norway spruce (Picea abies) stand in the Black Forest (southwest Germany) as differentiated by the soil pattern
Authors: Jungkunst H. F. , Fiedler S. , Stahr K.
Published: April 2004

Nitrous oxide is a greenhouse gas contributing to stratospheric ozone depletion with major sources that derive from soils. Most measurements were performed at well‐aerated or anaerobic sites, excluding common hydromorphic soils (e.g., Gleysols). The main thesis of this study was that the intermediate aeration of such soils promotes N2O emissions. The investigated catena “Wildmooswald,” which is little more than 200 m long, includes common temperate forest soils (n = 7) of three aeration categories (Cambisols, Gleysols, and Histosol). The influence of fluctuating water tables of the Gleysols led to distinctively higher N2O release compared to the Cambisol within the same mature Norway spruce ecosystem. Even a stable “hot spot” of N2O emissions was detected at a Histosol, where artificial drainage created a redox environment comparable to the Gleysols. Ranking the soils according to emission rate results in fairly regular doubling steps; for example, mean annual flux rates in kg N ha−1 yr−1 for the 2.5 years of measurements were −0.1, 0.4, 1.0, 1.9/1.9, 3.2, and 6.4 for Fibric Histosol, Chromic Cambisol, Endoskeletic Cambisol, Histic Gleysol 1/2, Humic Gleysol, and Sapric Histosol, respectively. The annual emission rates (0.93 kg N ha−1 yr−1) of the predominant Cambisols (63.4% of the area) are comparable to other studies, but only 34.3% of intermediately aerated soils led to a redoubling of the average to 1.86 kg N ha−1 yr−1, which is clearly higher than previously presented from temperate forests. Therefore N2O releases of soils are underestimated if soils having intermediate aeration conditions are left unconsidered.
Influence of chemical denudation on hillslope morphology
Authors: Mudd Simon Marius , Furbish David Jon
Published: April 2004

Models of hillslope evolution involving diffusion‐like sediment transport are conventionally presented as an equation in which the changes in land‐surface elevation or soil thickness are balanced by the divergence of soil transport and tectonic uplift, soil production, or both. These models typically do not include the loss or gain of mass in hillslope soils due to processes of chemical weathering and deposition. We formulate a more general depth‐integrated equation for the conservation of soil mass on a hillslope that includes a term representing chemical deposition or denudation. This general depth‐integrated equation is then simplified to determine the one‐dimensional form of a steady state hillslope which experiences both mechanical and chemical denudation. The differences in morphology between hillslopes only experiencing diffusion‐like mechanical sediment transport and hillslopes experiencing both diffusion‐like mechanical sediment transport and chemical denudation are explored. Under the conditions of a downslope increase in local soil lowering rate due to chemical weathering the hillslope profile will depart from the parabolic shape predicted by models that incorporate only linear diffusion‐like mechanical sediment transport. In addition, hillslopes that experience both chemical and mechanical denudation may have a convex‐concave profile at steady state. A necessary condition for such steady state profiles is that the chemical denudation rate must exceed the mechanical denudation rate. We further suggest that combinations of other physical parameter values (such as total denudation rate, average soil depth, sediment diffusivity, and the increase in soil depth away from the divide) that lead to steady state convex‐concave hillslope profiles may exist in a wide variety of natural settings.
Investigation on L‐shaped planar antennas
Authors: Ammann M. J. , Chen Zhi Ning
Published: April 2004

An L‐shaped planar antenna is investigated numerically and validated experimentally. The effect of varying the ratio of the height of vertical segment to the length of horizontal segment is examined in relation to the impedance bandwidth, radiation pattern, and mode of operation. The study shows that the L‐shaped planar antennas with different height‐to‐length ratios operate in different modes and feature distinct impedance and radiation characteristics.
Irreducible Brillouin conditions and contracted Schrödinger equations for n-electron systems. III. Systems of noninteracting electrons
Authors: Kutzelnigg Werner , Mukherjee Debashis
Published: April 2004

We analyze the structure and the solutions of the irreducible k-particle Brillouin conditions (IBCk) and the irreducible contracted Schrödinger equations (ICSEk) for an n-electron system without electron interaction. This exercise is very instructive in that it gives one both the perspective and the strategies to be followed in applying the IBC and ICSE to physically realistic systems with electron interaction. The IBC1 leads to a Liouville equation for the one-particle density matrix γ1=γ, consistent with our earlier analysis that the IBC1 holds both for a pure and an ensemble state. The IBC1 or the ICSE1 must be solved subject to the constraints imposed by the n-representability condition, which is particularly simple for γ. For a closed-shell state γ is idempotent, i.e., all natural spin orbitals (NSO’s) have occupation numbers 0 or 1, and all cumulants λk with k⩾2 vanish. For open-shell states there are NSO’s with fractional occupation number, and at the same time nonvanishing elements of λ2, which are related to spin and symmetry coupling. It is often useful to describe an open-shell state by a totally symmetric ensemble state. If one wants to treat a one-particle perturbation by means of perturbation theory, this mainly as a run-up for the study of a two-particle perturbation, one is faced with the problem that the perturbation expansion of the Liouville equation gives information only on the nondiagonal elements (in a basis of the unperturbed states) of γ. There are essentially three possibilities to construct the diagonal elements of γ: (i) to consider the perturbation expansion of the characteristic polynomial of γ, especially the idempotency for closed-shell states, (ii) to rely on the ICSE1, which (at variance with the IBC1) also gives information on the diagonal elements, though not in a very efficient manner, and (iii) to formulate the perturbation theory in terms of a unitary transformation in Fock space. The latter is particularly powerful, especially, when one wishes to study realistic Hamiltonians with a two-body interaction.