bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental middle ear surgery in rabbits: a new approach for reconstructing the ossicular chain
Authors: Stieve M , Hedrich H J , Battmer R D , Behrens P , Müller P , Lenarz Th
Published: March 2009

This experimental animal study aimed at evaluating a new prosthesis to replace the ossicular chain; we developed a new technique for surgical implantation into the middle ear of rabbits. The rabbit middle ear is, owing to the relative anatomical dimensions involved, an ideal environment for implantation procedures involving the ossicles, as the surgical conditions are similar to those of the human middle ear. This study included a total of 34 approximately six-month-old female white rabbits (New Zealand) weighing between 3.2 and 4.4 kg. The implants used were constructed of ceramic materials (titania, TiO2) of various pore sizes. Directly prior to implanting the total ossicular reconstruction prostheses (TORPs), as well as at 28, 84 and 300 days after implantation, electric response audiometry was used to determine the hearing thresholds of the animals (bone conduction; click stimulus nHL). An erbium:YAG laser was used to excise the original ossicular chain. Following implantation, we were unable to detect any stenosis of the outer ear canal or perforation of the tympanic membrane. The conductive hearing threshold was in the range of 4.21 ± 6.68 dB nHL ( n = 131). The hearing level showed no significant difference before and after surgery ( P < 0.05).
A novel dietary restriction method for group-housed rats: weight gain and clinical chemistry characterization
Authors: Kasanen I H E , Inhilä K J , Nevalainen J I , Väisänen S B , Mertanen A M O , Mering S M , Nevalainen T O
Published: March 2009

Laboratory rodents are usually fed ad libitum. Moderate dietary restriction decreases mortality and morbidity compared with ad libitum feeding. There are, however, problems in achieving dietary restriction. Traditional methods of restricted feeding may interfere with the diurnal rhythms of the animals and are not compatible with group-housing of rodents. We have invented a novel method, the diet board, for restricting the feed intake of laboratory rats. The use of the diet board moderately decreased weight gain of rats when compared with ad libitum-fed animals. The diet board retarded skeletal growth only minimally, whereas major differences were found in body fat depositions. Serum free fatty acid, triglyceride and cholesterol values were lower in diet-restricted rats, while the opposite was true for serum creatine kinase. There were no differences in total protein, albumin or alanine aminotransferase. Moreover, differences in interindividual variances in parameters were not detected between the groups; hence this study could not combine the diet board with reduction potential. The diet board provides mild to moderate dietary restriction for group-housed rats and is unlikely to interfere with the diurnal eating rhythm. The diet board can also be seen as a cage furniture item, dividing the open cage space and increasing the structural complexity of the environment. In conclusion, the diet board appears to possess refinement potential when compared with traditional methods of dietary restriction.
Blockbuster Culture's Next Rise or Fall: The Impact of Recommender Systems on Sales Diversity
Authors: Fleder Daniel , Hosanagar Kartik
Published: March 2009

This paper examines the effect of recommender systems on the diversity of sales. Two anecdotal views exist about such effects. Some believe recommenders help consumers discover new products and thus increase sales diversity. Others believe recommenders only reinforce the popularity of already-popular products. This paper seeks to reconcile these seemingly incompatible views. We explore the question in two ways. First, modeling recommender systems analytically allows us to explore their path-dependent effects. Second, turning to simulation, we increase the realism of our results by combining choice models with actual implementations of recommender systems. We arrive at three main results. First, some well-known recommenders can lead to a reduction in sales diversity. Because common recommenders (e.g., collaborative filters) recommend products based on sales and ratings, they cannot recommend products with limited historical data, even if they would be rated favorably. In turn, these recommenders can create a rich-get-richer effect for popular products and vice versa for unpopular ones. This bias toward popularity can prevent what may otherwise be better consumer-product matches. That diversity can decrease is surprising to consumers who express that recommendations have helped them discover new products. In line with this, result two shows that it is possible for individual-level diversity to increase but aggregate diversity to decrease. Recommenders can push each person to new products, but they often push users toward the same products. Third, we show how basic design choices affect the outcome, and thus managers can choose recommender designs that are more consistent with their sales goals and consumers' preferences.
Highbrow Films Gather Dust: Time-Inconsistent Preferences and Online DVD Rentals
Authors: Milkman Katherine L. , Rogers Todd , Bazerman Max H.
Published: March 2009

We report on a field study demonstrating systematic differences between the preferences people anticipate they will have over a series of options in the future and their subsequent revealed preferences over those options. Using a novel panel data set, we analyze the film rental and return patterns of a sample of online DVD rental customers over a period of four months. We predict and find that should DVDs (e.g., documentaries) are held significantly longer than want DVDs (e.g., action films) within customer. Similarly, we also predict and find that people are more likely to rent DVDs in one order and return them in the reverse order when should DVDs are rented before want DVDs. Specifically, a 1.3% increase in the probability of a reversal in preferences (from a baseline rate of 12%) ensues if the first of two sequentially rented movies has more should and fewer want characteristics than the second film. Finally, we find that as the same customers gain more experience with online DVD rentals, the extent to which they hold should films longer than want films decreases. Our results suggest that present bias has a meaningful impact on choice in the field, and that people may learn about their present bias with experience and, as a result, gain the capacity to curb its influence.
Scheduling of Container Storage and Retrieval
Authors: Vis Iris F. A. , Roodbergen Kees Jan
Published: March 2009

We consider the problem of scheduling the storage and retrieval of containers in the storage area of a container terminal. Some arcs in the underlying directed network must be visited; other arcs may be—but need not be—visited. We can, therefore, consider this problem to be a special case of the directed rural postman problem. We show that this problem can be reformulated as an asymmetric Steiner traveling salesman problem. This reformulation can be efficiently solved to optimality by a combination of optimal assignments in bipartite networks for parts of the problem and dynamic programming for the connections between those parts.
Analysis of Airplane Boarding Times
Authors: Bachmat Eitan , Berend Daniel , Sapir Luba , Skiena Steven , Stolyarov Natan
Published: March 2009

We model and analyze the process of passengers boarding an airplane. We show how the model yields closed-form estimates for the expected boarding time in many cases of interest. Comparison of our computations with previous work, based on discrete-event simulations, shows a high degree of agreement. Analysis of the model reveals a clear link between the efficiency of various airline boarding policies and a congestion parameter that is related to interior airplane design parameters, such as distance between rows. In particular, as congestion increases, random boarding becomes more attractive among row-based policies.
The perception of false self scale for adolescents: Reliability, validity, and longitudinal relationships with depressive and anxious symptoms
Authors: Weir Kirsty F. , Jose Paul E.
Published: March 2009

A scale assessing generalized false self‐perceptions (Perceptions of False Self, POFS) was developed and tested across three studies involving a total of 331 adolescents (11–16 years). In Study 1, interviews were conducted to develop items for the scale. In Study 2, psychometric techniques were used to derive a scale composed of 16 items. Study 2 also assessed the validity of the scale: depressive symptoms were found to increase POFS across 10 weeks, whereas false self‐perceptions had a reciprocal effect on anxiety. In Study 3, the convergent validity of the POFS scale was established. Overall, the evidence suggests that the POFS scale is a reliable and valid measure of generalized false self‐perceptions.
When Gods Don’t Appear: Divine Absence and Human Agency in Aristophanes
Authors: Given John
Published: March 2009

Surprisingly few gods appear in the eleven surviving comedies of Aristophanes. This article examines what roles the gods do play when they are present. It further argues that humans with divine attributes often appear in lieu of the gods themselves. These humans, together with the handful of gods who are present, fall into the broad functional categories of helpers and opponents of the comic protagonist. The gods’ absence is to be attributed to an Aristophanic conception of human agency, namely that humans in comedy, especially when compared to tragedy, have extraordinary control of their lives. A god’s presence would be too great a threat to comic inventiveness.
The Peroration of Cicero’s Pro Milone
Authors: Tzounakas Spyridon
Published: March 2009

By employing the figure of prosopopoeia / sermocinatio in the peroration of his Pro Milone , Cicero aims not only at reinforcing Milo’s favorable portrayal and the lines of defense, but also at protecting his own image following the legal defeat and at indirectly embarking on self-praise. The implied prediction of Cicero’s literary fame and glory, the information about his person, the atmosphere of death that brings to mind epitaphs, and the poetic motifs presented at the end of the speech could be interpreted as an intentional strategy that allows the orator to provide a sphragis for his work.
Statius’ Horatian Lyrics, Silvae 4.5 and 4.7
Authors: Nagel Rebecca
Published: March 2009

Statius makes use of Horatian forms and motifs, such as the simple house in the country and the literary help of a friend, but his tone is fervent and sincere, rather than dry and ironic. Statius is also fully aware of Horace’s generic choices, but makes different choices for his own work with no apparent anxiety. With many literary allusions, the poor and humble poet praises the wealth and public accomplishments of Septimius Severus and Vibius Maximus and at the same time shows how like-minded they are in their attitudes to literature, friendship, and wealth.
Once More on Hesiod’s Supposed Tartarus Principle
Authors: Beall E. F.
Published: March 2009

This note supports recent skepticism of the dominant construal of the neuter plural form τάρταρα at Hesiod, Theogony 119, whereby the term is in the nominative case, really stands for the masculine singular entity Τάρταρος that epic elsewhere cites as an underworld place-name, and is personified as a fourth original principle along with the Chaos, Gaea, and Eros of vv. 116–122, in favor of an interpretation whereby the term is an accusative referring to plural entities that are claimed to be held by the gods in addition to their holding Olympus, as in 118.
Teaching the Elegiac Lover in Ovid’s Amores
Authors: Katz Phyllis
Published: March 2009

This paper explores the evolution of views of Ovid’s elegiac lover. To counteract the tendency to define Ovid as a poet whose humor and irony were weaknesses, recent approaches have explored the complexities of Ovid’s lover, seeing him as both dominated by his puella and as her shrewd manipulator, a true desultor amoris . The paper summarizes five different approaches to the Amores (those of Paul Veyne, J. T. Davis, Barbara Weiden Boyd, Ellen Greene, and Sharon James), and in addition suggests a series of steps that might be used in the classroom to enhance students’ understanding of Ovid’s elegiac lover.
Primus Amor Phoebi
Authors: Miller John
Published: March 2009

This paper explores how Ovid’s announcement of Daphne as Ovid’s first love, and thus of the first of the numerous erotic stories in the Metamorphoses , is richly inscribed with allusions to literary beginnings—namely the openings of the Iliad , Odyssey , and Aeneid , the start of the war in Vergil’s epic, the transition from Delian to Pythian story in the Homeric Hymn to Apollo , the beginning of Propertius’ first book of elegies, and (most famously) Ovid’s own Amores 1.1. How these epic and elegiac intertexts reverberate with one another is also considered.
Select Ovid
Authors: Newlands Carole
Published: March 2009

The teaching of Ovid’s Metamorphoses , a popular text for intermediate and advanced-level undergraduates, of necessity involves selected myths. But as a result the students are not given a sense of the poem’s complex thematic interrelationships or of its sophisticated chronological sweep; selections also often overlook the importance of the female voice in Ovid’s epic. Read in isolation, moreover, the stories generally invite a moralizing approach that overlooks the nuances gleaned from their broader contexts. Reading the Metamorphoses simultaneously in translation would widen the scope of the students’ understanding of this poem’s sophisticated narrative and thematic texture.
Ulysses’ Wounds in the Contest over the Arms of Achilles
Authors: Pavlock Barbara
Published: March 2009

In the contest for Achilles’ arms in Metamorphoses 13, Ulysses exploits the significance of a warrior’s wounds. Responding to Ajax’s criticism that his shield has no spear marks, Ulysses boasts of his chest wounds but simultaneously casts doubt on their existence by playing on the meaning of the word pectora . Ulysses furthermore calls the significance of battle wounds into question by offering opposing positions, including his claim that Hector emerged from his contest with Ajax unscathed. Through conflicts with Iliad 7 and Odyssey 11, Ovid has Ulysses as well as the poet himself undermine traditional heroic values.
Recipe for Disaster: Motherhood and Citizenship at Love Canal
Authors: Hay Amy M.
Published: March 2009

In 1978, approximately 900 families living in the LaSalle neighborhood of Niagara Falls, New York discovered that over 22,000 tons of toxic chemicals were buried in their midst. In response residents formed the Love Canal Homeowners' Association, which demanded state aid in relocating families, and neighborhood women became the organization's most visible leaders. While the group's protests and use of the media were clearly influenced by civil rights and other postwar social movements, its rhetoric emphasized state obligation to protect reproduction, children, and homes. Despite the women's liberation movement of the 1960s and 1970s, Love Canal women argued for relocation based on their traditional domestic roles. This maternalist activism demonstrates the mixed legacy of postwar social movements and the emergence of heterosexual reproduction as the basis of citizenship in 1980s America. This research contributes to the histories of women's political activism, public health and environmentalism, and 1970s America.
African American Women, Prohibition, and the 1928 Presidential Election
Authors: Materson Lisa G.
Published: March 2009

This article explores links that middle-class African American women drew between efforts to repeal the Eighteenth Amendment and the emergence of black Democrats in the 1928 American presidential election. Because of their longstanding interest in civil rights and temperance, middle-class black Republican women were uniquely positioned to make connections between phenomena that historians have typically analyzed separately, the repeal movement and the early stages of the voting realignment. They argued that Democratic success in repealing the Eighteenth Amendment would set a precedent for eliminating the Reconstruction Amendments. They also identified black opposition to prohibition as threatening to racial uplift ideology, a class-based anti-racist strategy that, among other proscriptions, demanded abstention from liquor. Black Republican women's decision to invoke this declining ideology and blend it with their constitutional observation undercut not only the broad appeal of their constitutional argument, but also their claims to represent African Americans in party politics.
New Avenues for Domestic Dispute and Divorce Lawsuits along the U.S.-Mexico Border, 1832–1893
Authors: Valerio-Jiménez Omar S.
Published: March 2009

After the Mexican-American War (1846–1848), the United States assumed control over the area in southern Texas between the Nueces and Rio Grande rivers. As former Mexican citizens became U.S. citizens, American civilian officials obtained control over marital relations in the newly annexed territory. Using court records from Mexico and the United States, this article compares the domestic dispute and divorce lawsuits of residents living under Mexican jurisdiction between 1832 and 1846 to those living in the same region under United States jurisdiction between 1849 and 1893. Jurisdictional changes increased women's legal freedom to resolve domestic disagreements, introduced new legal marital expectations, and decreased the Catholic Church's legal influence over marital relations. This analysis suggests a reinterpretation of the post-annexation era; rather than being a period characterized by declension, it was one filled with both positive and negative results.
Women of the Mexican Oil Fields: Class, Nationality, Economy, Culture, 1900–1938
Authors: Santiago Myrna
Published: March 2009

The Mexican oil industry during the period of foreign ownership, 1900–1938, has inspired scholarship covering a myriad of actors, but not women. This article proposes to fill in that gap, documenting the experiences of foreign and Mexican women in the cradle of the industry, northern Veracruz and Tampico, Tamaulipas. This article argues that women were not only present in the oil fields, but that they were also indispensable for the economic success of the oil enterprise as a whole. Nevertheless, the experiences of women were quite diverse, depending on such factors as class and nationality. For Mexican women in particular, life in oil country meant revolutionary changes, even if capitalist structures and patriarchal culture remained intact.
"Unpensioned Veterans": Women Teachers and the Politics of Public Service in the Late-Nineteenth-Century United States
Authors: Leroux Karen
Published: March 2009

This article offers a new interpretation of the creation of teachers' pensions and contributes to the scholarly dialogue about gender and welfare state formation in the United States. To date, historians have regarded teachers' pensions as a form of compensation much like salary. Established just after the 1890 expansion of Civil War veterans' pensions, however, teachers' pensions represented more than deferred pay. They were designed to acknowledge women teachers' sacrifices and secure their long, loyal, underpaid service in public schools. This study argues that women teachers and policymakers looked to pensions as a solution for social problems emerging from the shift away from the family economy and its informal relations of obligation to a wage economy driven by relations of exchange. Both groups used pensions as a means to negotiate a relationship that incorporated some features of the market economy while introducing new mechanisms to protect deserving women against it.
Measurement of Roller Compactor Induced Triaxial Soil Stresses and Strains
Authors: Rinehart Robert V. , Mooney Michael A.
Published: March 2009

The measurement of soil properties via roller compactor-integrated instrumentation has gained increased attention. Employing roller-based measurement of mechanistic soil properties for quality assurance or performance prediction has significant potential benefits. To advance the development and understanding of static and vibratory roller measurement systems, the geotechnical community must better understand soil behavior during roller loading. This paper describes the development and implementation of an experimental program to measure in-situ triaxial normal stresses and strains during static and vibratory roller passes. Field tests revealed complex triaxial stress-strain behavior with near plane-strain conditions beneath the center of the drum. The observed stress response matched well with behavior predicted by Hertzian elastic contact theory. The soil stiffness dependent drum/soil contact width plays a significant role in stress distribution and depth of influence of the roller. The influence of drum vibration and static roller weight are visible in stress and strain measured during vibratory operation. The curved drum significantly influences the induced stresses and strains. The results presented here reveal that rollers induce stresses and strains to depths approaching 2 m and that the stress state imparted by the roller is more complex than that used in resilient modulus testing.
Using Rheology Test Methods to Assess Durability of Cured Elastomers Undergoing Cyclic Deformation
Authors: Gordon Glenn V. , Lower Loren D. , Carbary Lawrence D.
Published: March 2009

The current measurement test method to assess elastomeric sealant durability is ASTM C719. This method requires a minimum of five weeks of curing and conditioning before being subjected to ten movement cycles at room temperature and then ten movement cycles at variable temperatures. This method is a fine predictor of sealant movement capability for products used in moving joints in commercial construction applications. ASTM E1886 suggests that building assemblies be subjected to 9000 cycles of wind pressure. Sealant materials are typically used to anchor glazing assemblies into frames, and the choice of the correct sealant is critical to passing the test criteria specified in ASTM E1866. Rheological instruments have the capability to characterize the dynamic mechanical behavior of elastomeric materials undergoing oscillatory (cyclic) deformation under controlled test conditions and, therefore, provide a laboratory tool for assessing durability. Cyclic testing can be conducted under controlled strain (deformation) conditions at frequencies that simulate joint movement due either to thermal expansion differentials or seismic events, or under controlled stress (load) that model hurricane-force wind loads or design pressures. An immediate stress-softening response was observed from controlled-strain experiments at 15 % movement that was ascribed to the Mullins effect; however, three of the four cured silicone sealants exhibited a modest recovery over the remaining four days of cyclic testing. Under controlled-stress cycling at 0.138 MPa for 150 minutes at 0.5 Hz, the silicones exhibited ultimate deformations well below their rated movement capabilities. The results from both types of rheology test methods did not reveal outward signs of fatigue and suggest which elastomeric materials will perform better under the drastic cycling that occurs in ASTM E1866 and ASTM C719 testing.
Evaluation of the EPA Drift Reduction Technology (DRT) Low-Speed Wind Tunnel Protocol
Authors: Fritz Bradley K. , Hoffmann W. Clint , Lan Yubin
Published: March 2009

The EPA’s proposed Drift Reduction Technology (DRT) low-speed wind tunnel evaluation protocol was tested across a series of modified ASAE reference nozzles. Both droplet size and deposition and flux volume measurements were made downwind from the nozzles operating in the tunnel at airspeeds of 1 m/s and 2.5 m/s, following the prescribed protocol. Overall, the data followed anticipated trends with a few unanticipated results observed, which could be addressed in future iterations of the protocol. There were some difficulties meeting the proposed protocol data quality requirements. Refined quality requirements would address this with no detrimental effect to the overall data set. Major concerns, at this point, are the feasibility of the overall protocol as well as the applicability of the final collected data. The protocol was tailored such that the collected data would directly input into a dispersion model (most likely WTDISP). However, not having access to such a model puts into question the validity and practicality of the protocol in its present form. Given the time requirements, which require approximately nine times that of the high speed protocol (90 min versus 10 min, unpublished data), there is a definite need to modify the existing protocol to insure equitable implementation of the overall DRT program.
Improvements in the Mercury Displacement Method for Measuring Diffusible Hydrogen Contents in Steels
Authors: Senadheera Thushanthi D. A. A. , Shaw W. J. D.
Published: March 2009

The mercury displacement method, also known as the eudiometer method, is one of the most widely used, reliable, and low cost techniques of determining hydrogen quantities in steels. This is one of the few direct and simple techniques for measuring diffusible (mobile) hydrogen quantities. It was originally developed for measuring hydrogen pickup in steels as a result of the welding process, ANSI/AWS A 4.3 standard. However, it is often applied in a more general sense to the measurement of mobile hydrogen in steels as picked up from a wide variety of sources. The main limitation in using this technique is one of safety concerns in handling mercury and controlling the mercury fumes that are given off. This paper describes and suggests a number of modifications and improvements that have been developed from experience over the past couple of years. The modifications increase the accuracy and significantly enhanced the level of safety. The system can be run at moderately high temperatures up to 180°C with minimal mercury vapor loss.
Leben lernen. Anthropologische Anmerkungen zu einem pädagogischen Thema
Authors: Zirfas Jörg
Published: March 2009

Unter Leben lernen kann verstanden werden: eine existentielle Sinndimension des Lebens gewinnen, eine sozial-stabilisatorische Umgebung erlangen, einen kritisch-subjektiven Widerstand entfalten, eine individuelle Kohärenz stiften, ein originelles Dasein führen, und sich in die Abschiedlichkeit einüben. Durch Erfahrungen, die die menschliche Selbstbestimmung, die Widersprüchlichkeit und Endlichkeit menschlichen Lebens betreffen, werden Prozesse des Leben Lernens eröffnet.
Tod, Schlafes Bruder. Intertextuelle Streifzüge und Fallstudien
Authors: Scherer Burkhard
Published: March 2009

Dieser Beitrag analysiert das klassische Mythem / Motiv vom Tod als Bruder des Schlafes literaturhistorisch von Hesiod bis zur europäischen Romantik. Am Kernbeispiel von Spauns Der Tod und der Jüngling (1817) werden die Fülle möglicher intertextueller Techniken und Grundformen aufgezeigt. Gerade wegen seiner eklatanten Durchschaubarkeit erweist sich Spauns Gelegenheitsdichtung als besonders geeignetes Lehrstück einer poetischen Technik.
Alles nur Theater oder Wirklicher als die Wirklichkeit?
Authors: Seitz Hanne
Published: March 2009

Ein Schauspieler auf einem Acker in Brandenburg. Er setzt Kartoffeln und fühlt sich dabei in die Rolle des Flint aus Heiner Müllers Stück Die Umsiedlerin ein  er rackert sich also buchstäblich ab und thematisiert nicht nur die Arbeit des Schauspielers an sich selbst (Stanislawski), sondern auch die Fusion von Kunst und Leben, ergründet neue Arbeitsmodelle in einer Gesellschaft, der die Lohnarbeit ausgeht und die sich durch die künstlerische Kreativität neue Impulse erhofft.

Ist es Leben? Ist es Theater? Ist es Land Art? Mit Bauerntheater (Regie: David Levine) wird eine Aufführung diskutiert, die am Ende wirklicher als die Wirklichkeit ist.
Die Zukunft verhandeln. Aus der Sicht der Wissenschaftskommunikation in der Risikoforschung und Bioethik Japans
Authors: Suzuki Shoko
Published: March 2009

Wissenschaftskommunikation, das ist ein ziemlich neues Wort. Um die Kluft zwischen Wissenschaftlern (Experten) und allgemeinen Bürgern (Nicht-Experten) zu verringern, ist heute nicht nur die Frage der Aufklärung oder der Erziehung, sondern auch die Frage der allen risikovollen Praxis des Menschen wie Medizinische Kommunikation. Wie kann man dabei mit der Zukunft verhandeln?
Überlebt
Authors: Peskoller Helga
Published: March 2009

Die Frage, wie man Extremlagen überdauern und welche Erklärungen es dafür geben kann, wird am Beispiel von Reinhold Messners Buch überlebt gestellt und anhand von Textfragmenten, Bildern und Tonbandaufzeichnungen untersucht. Die Antwort läuft auf eine kleine Theorie des Überlebens hinaus, sie beinhaltet die Flucht nach vorn, den Übermut, das Zuwarten, den richtigen Moment zur Handlung nutzen, das Wiedererinnern, Weitermachen und Erzählen. Letzteres hat sich als die Voraussetzung für ein wiederholtes Überleben herausgestellt und diese Einsicht trägt nach einer verzweigten theoretischen Anbindungen zur Modifikation Blaise Pascals Formel bei: Nicht zwei Dinge  Instinkt und Erfahrung  unterrichten den Menschen über seine ganze Natur, sondern Erfahrung ist Instinkt.
Water Molecule Coupling to MeCl+ and MeClO4
+ Ions Studied by the Electrospray Ionisation Mass Spectrometry
Authors: Jakubowska Anna
Published: March 2009

The binding stability of water molecules with MeCl+ and MeClO4
+ ions has been studied by the electrospray ionisation mass spectrometry (ESI-MS). The Me ions studied were the typical transition metals (Me = Fe, Co, Ni, Cu, Zn, or Cd) and the typical alkaline-earth metals (Me = Mg, Ca, Sr, or Ba). The increasing voltage between the skimmer cones (referred to as the cone voltage) induced the abstraction of water molecules from MeCl+ and MeClO4
+ ions. The binding stability of water molecules with MeCl+ and MeClO4
+ ions has been correlated with the Me cation mass and with the heat capacity of hydration of Me cations. Moreover, the physicochemical properties of the ions studied have been compared by the cluster analysis and the principal component analysis of the experimental curves obtained for the [MeCl-H2O]+ and [MeClO4-nH2O]+ ions, where n is 1 or 2. Our results can be useful in examination of the ion dehydration process.
Thermodynamic and Transport Properties of Binary Liquid Mixtures of 1-Hexanol with Hexadecane and Squalane at 298.15, 303.15 and 308.15 K
Authors: Dubey Gyan P. , Sharma Monika
Published: March 2009

Excess molar volumes, V

m

E
, viscosity deviations, Δη, excess molar isentropic compressibility, K

E

S,m
, deviation of the speeds of sound, u

D
, from their ideal values u

id
in an ideal mixture for binary mixtures of 1-hexanol, C6H13OH with hexadecane, C16H34 and squalane (2,6,10,15,19,23-hexamethyltetracosane), C30H62 at T = (298.15, 303.15 and 308.15) K and at atmospheric pressure were derived from experimental density, ρ, viscosity, η and speed of sound data, u. The calculated excess and deviation functions were further fitted to the Redlich-Kister polynomial equation. The Prigogine-Flory-Patterson (PFP) theory has been applied to analyze V

m

E
of these systems and theoretical values of thermal expansivity, α, has also been calculated using Flory theory. Furthermore, the apparent molar volumes, V¯ϕ,i0 and apparent molar compressibility, K¯ϕ,i0 of the components at infinite dilution have been calculated.
Elaboration and Physico-Chemical Characterizations of the Series of Nanomaterials: Lithium-Substituted NASICONS with General Formula Li3.2Zr2-y
Si2.2–4y
P0.8+4y
O12 where (0 ≤ y ≤ 0.55)
Authors: Belam W.
Published: March 2009

The series of nanomaterials: lithium-substituted NASICONS with general formula Li3.2Zr2-ySi2.2–4y
P0.8+4y
O12 where 0 ≤ y ≤ 0.55, was synthesized by the sol-gel method which consisted in calcining the preliminary precursors at temperatures higher than their crystallization temperatures. The dried powders, at 373 K, of the five preliminary precursors were analyzed by coupled DTA-TGA in order to determine their crystallization temperatures and therefore leading to the estimation of their calcined temperatures. The calcined powders have been characterized by physico-chemical techniques: XRD and CIS. The XRD analyses show the obtaining of only the single phase without any detection of other phases as: ZrO2, SiO2, Li2O, ZrSiO4, Li3PO4, Li2SiO3 or Li2ZrO3, according to their JCPDS file cards and suggest that the decrease in the zirconium concentration does not modify the stability of the lithium-substituted NASICONS, whereas the complex impedance spectroscopy results have highlighted the best total electric conductivity for y value equal to 0.55.
Wetting of Sapphire by a Supercooled Silicon Droplet
Authors: Braun A. M. , Becker V. , Govori B. , Alphei L. , Gesing Thorsten M. , Buhl J.-Ch. , Becker J. A.
Published: March 2009

A small piece of silicon was melted in vacuum in a high precision spherical depression of a heated (0001) oriented sapphire substrate. The droplet was observed from above by use of a microscope equipped with a CMOS video camera. Above the melting point (1687 K) it exhibited small but rapid breathing mode fluctuations. The frequency of these fluctuations could be slowed down by supercooling the droplet to about 80 K below the melting temperature, allowing a detailed study of the effect. An unusual contour structure with a threefold rotation symmetry was observed, when the droplet had spread to its maximum contour diameter. This pattern can be related to the ditrigonal-scalenohedral 3¯m symmetry of the sapphire crystal.
Frequent Unanticipated Alleles of lethal giant larvae in Drosophila Second Chromosome Stocks
Authors: Roegiers Fabrice , Kavaler Joshua , Tolwinski Nicholas , Chou Yu-Ting , Duan Hong , Bejarano Fernando , Zitserman Diana , Lai Eric C
Published: March 2009

Forty years ago, a high frequency of lethal giant larvae (lgl) alleles in wild populations of Drosophila melanogaster was reported. This locus has been intensively studied for its roles in epithelial polarity, asymmetric neural divisions, and restriction of tissue proliferation. Here, we identify a high frequency of lgl alleles in the Bloomington second chromosome deficiency kit and the University of California at Los Angeles Bruinfly FRT40A-lethal P collection. These unrecognized aberrations confound the use of these workhorse collections for phenotypic screening or genetic mapping. In addition, we determined that independent alleles of insensitive, reported to affect asymmetric cell divisions during sensory organ development, carry lgl deletions that are responsible for the observed phenotypes. Taken together, these results encourage the routine testing of second chromosome stocks for second-site alleles of lgl.
Validation of a Management Program Based on A Weed Cover Threshold Model: Effects on Herbicide Use and Weed Populations
Authors: Simard Marie-Josée , Panneton Bernard , Longchamps Louis , Lemieux Claudel , Légère Anne , Leroux Gilles D.
Published: March 2009

Weed management decisions based on weed threshold models offer the opportunity to reduce herbicide use by allowing the possibility of forgoing treatment or lowering rates. Weed thresholds based on a relative leaf-cover model were tested during a 4-yr period at two locations. Two 1.62-ha fields, planted to conventional and glyphosate-resistant corn (2004, 2005, 2007) or soybean (2006), were divided in 900 m2sections. Herbicides were applied postemergence to each of these sections with either variable rates based on weed thresholds, or constant full rates. Variable herbicide rates included: no application, half rate, or full rate. Relative weed cover values of 0.2 and 0.4 (corn) or 0.1 and 0.3 (soybean) served as thresholds for incremental rates. Digital images were used to evaluate the relative weed cover. Weed density was assessed before and after herbicide application. Weed seed production was estimated for two species in 2004 and 2005. No difference in crop yield, relative weed cover, weed density, or weed seed production was observed between conventional and glyphosate-resistant cropping systems. During the first year, herbicide use reduction was obtained (−85.4%) with marginal crop yield loss (5 to 15%). In the subsequent 3 yr, preherbicide weed densities increased and concomitant increases in relative weed cover values did not allow more than a 10% overall reduction in herbicide use. This threshold model designed to maintain crop yields within a given year did not allow significant reduction in herbicide use during the following 3 yr. Residual weed populations most likely replenished the seed bank to levels that allowed weed densities to increase afterward. Increased weed density over time in plots treated with full rates of herbicide every year also indicated that a single postemergence herbicide treatment was not sufficient to contain weed populations at low levels every year in this corn–soybean rotation.
Population Ecology and Management of Rigid Brome (Bromus rigidus) in Australian Cropping Systems
Authors: Kleemann Samuel G. L. , Gill Gurjeet S.
Published: March 2009

Rigid brome is a problematic weed of southern Australian cropping systems. Increased knowledge about the ecology of rigid brome and the influence of management strategies on its seedbank dynamics could facilitate development of more effective weed control programs. A field study was undertaken to investigate seedbank persistence and the influence of different management strategies on rigid brome control at Lock in South Australia during 2003 to 2005. Seeds of rigid brome were found to persist in the soil for up to 3 yr, with > 20% of the seedbank persisting from one season to the next. Therefore, a single year management program against this weed species is likely to be ineffective and could result in rapid buildup in weed infestations. However, management strategies that combined effective herbicides (ClearfieldTMtechnology) and crop competition over consecutive years provided effective control of this troublesome weed. Such cropping systems reduced rigid brome density (1 to 10 plants m−2) and seed production (8 to 160 seeds m−2) in the final crop of the 3-yr cropping sequence as compared to common grower practice of trifluralin and triasulfuron mixtures (138 plants m−2; 1,866 seeds m−2). These treatment combinations were able to deplete the initial seedbank (1,748 seeds m−2) to manageable levels (< 5 seeds m−2) within 3 yr. The results of this study should provide growers with confidence that severe rigid brome infestations can be managed effectively without compromising crop productivity.
Germination Patterns in Naturally Chilled and Nonchilled Seeds of Fierce Thornapple (Datura Ferox) and Velvetleaf (Abutilon Theophrasti)
Authors: Dorado José , Fernández-Quintanilla César , Grundy Andrea C.
Published: March 2009

Seeds from natural populations of fierce thornapple and velvetleaf collected in a corn-growing area in central Spain were incubated at a range of constant temperatures and water potentials to model the progress of germination on the basis of the accumulation of hydrothermal time. Previous to the germination tests, the seeds were treated in two different ways: (1) dark storage under dry conditions (nonchilled seeds), and (2) burying in the original soil at 10-cm depth during 2 mo in winter (naturally chilled seeds). The results indicated different mechanisms inhibiting germination in both weed species. Whereas fierce thornapple displayed some type of embryo dormancy, the lack of germination in velvetleaf appeared to be entirely due to the seed coat. On the other hand, significant differences between nonchilled and naturally chilled seeds in fierce thornapple were observed, mainly due to the decrease in the mean base water potential of the 50th percentile in the latter, which indicated a loss of dormancy by exposure of the seeds to natural conditions. Hydrothermal time appears to be a good description of the germination patterns in both weed species, but in the case of fierce thornapple, only for naturally chilled seeds. Thus, the development of the hydrothermal model in fierce thornapple raises some questions for consideration concerning the influence of the type of seeds (conditions of storage, pretreatments of the seeds before germination tests) on its germination capacity.
Weed–Corn Competition Parameters in Late-Winter Sowing in Northern Italy
Authors: Otto Stefan , Masin Roberta , Casari Giorgio , Zanin Giuseppe
Published: March 2009

In recent years, interest has increased in late-winter sowing of corn in northern Italy because of many agronomic advantages. However, cold and rainy weather slows initial crop growth, which can favor weed infestation. There is, therefore, a need for appropriate timing of weed control tactics based on an understanding of the competitive relationship and dynamics between crop and weeds. Five experiments were conducted over 4 yr, with a series of treatments increasing either duration of interference or length of weed-free period. Yield data were fitted with sigmoidal equations to find the critical point (CP) and critical period of weed control (CPWC). Although the CP is determined only by the competition between weed and crop, the CPWC is also market dependent. To quantify the effect of weed flora on the CP, a multiple regression model was tested, taking into account weed density, inflection point, and slope parameter of the Gompertz model of the cumulated infestation. The results confirmed that the late-winter sowing date increases the importance of late winter– and early spring–emerging weeds. In general, the precompetitive period was longer in the late winter–sown corn than in traditional midspring-sown corn. The delayed start of the CPWC makes control more difficult with a preemergence herbicide, which raises questions on the utility of this agronomic technique. Multiple regression analysis showed that the position of CP can be estimated with the density, earliness, and competitiveness of the infestation. Furthermore, the slope/inflection point ratio of the Gompertz model appears to be independent of sowing date. Results suggest that the weed–crop competition mechanism can be represented with simply the weed flora dynamic parameters and that a combination of crop–weed competition studies and emergence prediction models can predict the position of CP and give useful information about the CPWC and weed management.
Living Boundaries: Tracking Weed Seed Movement With Nondormant Seed
Authors: Davis Adam S. , Luschei Edward C.
Published: March 2009

Synthetic seed banks are a useful tool for tracking how weed populations change over time. By sowing a known number of seeds of a given species within a quadrat with defined boundaries, an investigator can measure the number remaining and thereby calculate demographic rates (e.g., mortality). The alternative is to use in situ seeds and estimate their initial population density via sampling. To make a synthetic seed bank approach useful within an agricultural system subjected to soil disturbances such as tillage, one would need a way to account for seeds leaving the initial quadrat (i.e., a way to follow how the area encompassing the sown seeds changes over time). Without accounting for the change in location/extent of the synthetic seed bank, any field operation moving soil will create additional uncertainty in population size. Depending on the “aggressiveness” of specific field operations and the initial size of the quadrat, this effect might be negligible or so large as to be intractable. Here, we describe a method for following a synthetic seed bank over time using a “living boundary” of nondormant seeds, which effectively play the role of tracers used in the study of dynamics in other scientific disciplines. Study quadrats in East Lansing, MI, and Arlington, WI, were sown with giant foxtail and velvetleaf at a rate of 2,000 seeds m−2. The study quadrats were marked on the perimeter and diagonals using nondormant seeds of three marker species: kale, radish, and rye. The areas were then subjected to tillage and planting operations. Spatial coordinates of seedling locations for the marker and weed species were obtained through digital image processing. A nonparametric comparison of the spatial displacement of marker and weed species indicated that their empirical spatial distributions did not differ. The marker species quadrats described by the 50th, 90th, and 99th quantiles of movement contained all velvetleaf seedlings in Wisconsin, all velvetleaf seedlings in Michigan, and all giant foxtail seedlings in Michigan, respectively. The results suggest a simple rule for applying the method to field demography studies: after the original quadrat is deformed and seedlings have emerged, flag the polygon containing all marker seedlings to obtain the expanded quadrat containing the study weed population.
Red:Far-Red Light Effects on Corn Growth and Productivity in Field Environments
Authors: Markham Melinda Y. , Stoltenberg David E.
Published: March 2009

Increased reflection of far-red light among plants can lower the red:far-red ratio (R:FR) of horizontally-propagated light before substantial shading among plants occurs. Although previous research suggests that altered R:FR can affect corn growth, it is not understood how early-season low R:FR (associated with higher plant densities in corn–weed communities than in weed-free corn) affects corn productivity in the field. We conducted field experiments from 2005 to 2007 to determine the effects of reduced R:FR on corn growth and yield. Corn was established at 53,800 plants ha−1for a control R:FR treatment (weed-free corn) and at 107,600 plants ha−1for a low R:FR treatment (simulated corn–weed community). The low R:FR treatment was thinned to the control plant density at V7 corn (seven fully-expanded leaf collars), which simulated total weed removal. Before thinning, R:FR (645:735 nm) at V7 corn in the low R:FR treatment (0.23) was less than 50% of that in the control R:FR treatment (0.49) across years. In 2005, stalk diameter, stem length, stem mass, leaf mass, specific leaf area, and total plant mass were less for V5 corn in the low R:FR treatment than in the control R:FR treatment. In 2006, V5 corn was taller in the low R:FR treatment than in the control R:FR treatment, but other morphological characteristics were similar between treatments. The shoot:root ratio of V5 (five fully-expanded leaf collars) (2005) and V7 corn (2006) was not affected by R:FR treatment, nor was shoot mass and grain yield of R6 corn (physiological maturity). Measurements in 2006 indicated that soil moisture and nutrient availability were not limiting and did not differ between treatments. Early-season R:FR in simulated corn–weed communities was similar to that in in situ corn–weed communities. These results suggest that low R:FR typical of early-season corn–weed communities was not associated with corn grain yield loss under field conditions in which water and nutrients were not limiting resources.
The Euro and Convergence among Stock Markets of Germany, France and Italy
Authors: Rahman Matiur , Khan M. Moosa
Published: March 2009

This paper re-examines the role of the euro in enhancing the convergence among stock markets of Germany, France and Italy. The VAR-framework is implemented with a dummy variable. A pre- and post-euro analysis is also performed with an exclusion of the dummy variable. Monthly data on stock market returns from February 1994 through December 2007 are employed. The empirical results reveal evidence of significant convergence among the above markets during the post-euro era relative to the pre-euro era with net positive short-run causal effects.