bluuebunny/crossref_metadata_2025 huggingface dataset:
EXTENSION OF THE SHELF‐LIFE OF BURFI BY PACKAGING
Authors: VIJAYALAKSHMI NARASIMHACHAR S. , INDIRAMMA AMBUGA R. , VISWANATH PREMA , DATTATREYA ANUPAMA , KUMAR KONERIPATTI R.
Published: June 2005

Burfi, an Indian milk‐based sweet, is susceptible to microbial spoilage that restricts its shelf life to 10 days. Large‐scale marketability of burfi and its export potential requires longer shelf life. Therefore, our aim was maximizing shelf life by packaging means. Studies were carried out on burfi in different packaging materials under different atmospheres – normal packing, vacuum packing and use of a free‐oxygen absorber – at 65% RH/27C. Normal packing even in barrier film did not effectively control microbial spoilage. Vacuum packing, although it retarded microbial growth, adversely affected texture and sensory quality. A free‐oxygen absorber coupled with high‐barrier materials like metallized films/foil laminates offered more than 45 days shelf life. Stored samples could be grouped by principal component analysis. The major sensory attributes contributing to grouping were color, firmness, chewiness, creamy and rancid notes. Sensory firmness and chewiness were found to have good correlation with instrumentally measured texture values.
PHYSICOCHEMICAL PROPERTIES OF FRESHLY BAKED AND STORED WHOLE‐WHEAT MUFFINS WITH AND WITHOUT FLAXSEED MEAL
Authors: SHEARER ADRIENNE E.H. , DAVIES CATHERINE G.A.
Published: June 2005

Whole‐wheat muffins and batter were prepared with 0–5% flaxseed meal or by direct substitution of vegetable oil with flaxseed oil, and were evaluated for physicochemical properties. The storage properties of muffins were evaluated over 5 days at 0.44 relative vapor pressure (RVP) and ambient temperature. Batter viscosity increased from 2730 ± 530 to 12,775 ± 4425 cps with increasing flaxseed meal content while other properties were unaffected. When flaxseed meal was added at 5%, the maximum force for compression of freshly baked muffins increased from 369.6 ± 3.0 to 594.6 ± 10.2 g while the internal elasticity decreased from 60.2 ± 0.5 to 55.4 ± 1.6. Freshly baked muffins with flaxseed meal had lower color scores, L, andavalues than control muffins. The storage stability of muffins was unaffected by the addition of flaxseed meal. Flaxseed meal or oil can be used in muffins to enhance the nutritional value without detrimentally changing the freshness or storage properties.
PHYSICAL, CHEMICAL AND SENSORY PROPERTIES OF SUGAR‐FREE JELLY*
Authors: KHOURYIEH HANNA A. , ARAMOUNI FADI M. , HERALD THOMAS J.
Published: June 2005

The increase in diabetes and obesity has increased the demand for sugar‐free/low‐calorie products. Three jelly formulations were prepared using sucralose, low‐methoxyl pectin and maltodextrin with either xanthan gum or locust bean gum (LBG) used singly or in combination and stored at 4C or 43C for shelf life evaluation. Jelly treatments were evaluated for chemical, physical and sensory properties. The combination of xanthan gum and LBG significantly reduced syneresis compared with either gum used singly. The combination of xanthan gum and LBG resulted in significantly higher firmness and springiness values than using xanthan gum or LBG alone. The overall acceptability, aroma, taste, texture, spreadability and sensory attributes for no sugar‐added grape jelly averaged 5.8–6.4 in a 9‐point hedonic scale consumer acceptance study.
ACOUSTIC ENVELOPE DETECTOR FOR CRISPNESS ASSESSMENT OF BISCUITS
Authors: CHEN JIANSHE , KARLSSON CATHRINE , POVEY MALCOLM
Published: June 2005

The crispness of food materials based on the force/displacement behavior and their acoustic nature was assessed using an Acoustic Envelope Detector (AED) attached to the Texture Analyzer, wherein six kinds of biscuits were used: Carr's Table Water, Crackerbread, Digestive, Dutch Crispbakes, Rich Tea fingers and Shortbread. The force/displacement and acoustic signals were simultaneously recorded during the breakup of biscuits. For each detected acoustic signal, there was a sudden drop in the compression force. The analysis of the force/displacement curve demonstrated the links between the second derivative of force curve and the acoustic event, indicating the energy released through the air of these crack events. The acoustic behavior of the biscuits was assessed in terms of maximum sound pressure level and the number of acoustic events, which were further interpreted as the acoustic events per unit area of newly created surface area and the acoustic event per unit time. The acoustic ranking of biscuits from instrumental assessment was in very good agreement with that from sensory panel tests. The normal integration time (1.25 ms) for the AED was generally effective in detecting acoustic signals for crisp biscuits, but a shorter integration time (0.25 ms) was found advantageous in detecting acoustic signals that occur within a very short time period and gave better differentiation of crisp biscuits.
RELATION BETWEEN SENSORY TEXTURE PROPERTIES AND EXOPOLYSACCHARIDE DISTRIBUTION IN SET AND IN STIRRED YOGHURTS PRODUCED WITH DIFFERENT STARTER CULTURES
Authors: FOLKENBERG DITTE MARIE , DEJMEK PETR , SKRIVER ANNE , IPSEN RICHARD
Published: June 2005

Set yoghurts produced with seven different exopolysaccharide‐producing starter cultures were subjected to sensory texture profiling including texture evaluation before and after a stirring procedure carried out by trained assessors. The microstructure of four selected yoghurts was investigated by confocal laser scanning microscopy with special focus on the distribution of exopolysaccharides (EPS) in the protein network. Two different types of microstructures were observed, one in which EPS were associated with the protein network and another where EPS appeared to be incompatible with the protein; as a consequence, the EPS were situated in the void spaces in the protein network. The latter yoghurts were less ropy and had higher serum separation than the yoghurts where EPS were associated with the protein, and they exhibited a significant increase in mouth thickness as a result of stirring. Yoghurts in which the EPS were associated with protein had high ropiness, low serum separation and appeared more resistant to stirring. The nature of EPS‐protein interactions is extremely important for the textural effects of EPS in fermented milk products, and such interactions depend on the specific starter culture used.
RHEOLOGICAL PROPERTIES OF RENNET‐INDUCED GELS DURING THE COAGULATION AND CUTTING PROCESS: IMPACT OF PROCESSING CONDITIONS
Authors: MISHRA RITU , GOVINDASAMY‐LUCEY SELVARANI , LUCEY JOHN A.
Published: June 2005

The effects of gelation temperature (GT), pH, milk solids nonfat (MSNF) content and aging time on the small and large deformation rheological properties of rennet‐induced skim milk gels were studied. Small amplitude oscillatory rheometry (SAOR) was used to study gel formation. A constant shear rate was applied to gels of various ages to try to simulate the cutting process used in cheese vats. Second‐order polynomial models successfully predicted (R2 ≥ 0.83) the relationship between processing parameters and rheological properties of gels. The processing parameters – gelation pH, GT and MSNF – had a significant effect on the rheological properties of rennet‐induced gels. The type and the nature of bonds in these networks and the time scale of applied deformation affected the rheological properties of rennet gels. As time after rennet addition increased, storage modulus, loss modulus and yield stress values increased. This resulted from an increase in the number and strength of bonds with time. The yield strain decreased with time probably because of rearrangements in the network making the gel shorter/brittle in texture. When the impact of the time scale of the applied deformation was compared between the small (storage modulus as a function of frequency) and large (yield stress as a function of constant shear rate) deformation properties of rennet‐induced gels, similar power law exponents were obtained. This similarity presumably reflects the type and relaxation behavior of bonds in this casein network. These results identify the impact of several important processing variables on both the small and the large deformation rheological properties of rennet‐induced gels, which could be useful in identifying gelation properties that improve cheese yield.
MODELING OF THICKNESS FOR SEMISOLID FOODS
Authors: TERPSTRA MARJOLEIN E.J. , JANSSEN ANKE M. , PRINZ JON F. , DE WIJK RENÉ A. , WEENEN HUGO , VAN DER LINDEN ERIK
Published: June 2005

We investigated the relationship between orally perceived thickness and calculated shear stress on the tongue for mayonnaise and custard. To this end, the applicability of the models of Kokini et al. (1977), describing the mechanical breakdown in the mouth, have been tested. Within a limited range of shear stresses (mayonnaise < 150 Pa; custard < 30 Pa), there was a linear relationship between shear stress and thickness, in accordance with the work of Kokini et al. (1977). Beyond this range, the linear relationship breaks down and the thickness levels off with shear stress for both mayonnaise and custard. The relationship over the entire range of shear stresses used in this paper can be satisfactorily described by a semilogarithmic (Fechner) relation. For both types of products, the quality of the thickness prediction by the decreasing‐height model and the constant‐height model of Kokini et al. (1977) is similar. For most mayonnaises, the contribution of the lateral movement of the tongue to the shear stress in the decreasing‐height model of Kokini et al. (1977) is orders of magnitude larger than the contribution of the squeezing or compression movement of the tongue towards the palate. This difference in magnitude is affected by the low value measured for the compression force and by the high values for material consistency K. The values for K are high because yield‐stress behavior has been neglected when the flow curves were analyzed. For custard, the models of Kokini et al. (1977) are found to be less adequate. It is proposed that this is because the models ignore interactions with saliva. Several routes to improve the modeling by incorporating viscoelastic behavior were unsuccessful. Elongational stress and yield stress were neglected in all tested models.
Verification of the exponential model of body temperature decrease after death in pigs
Authors: Kaliszan Michał , Hauser Roman , Kaliszan Roman , Wiczling Paweł , Buczyñski Janusz , Penkowski Michał
Published: June 2005

The authors have conducted a systematic study in pigs to verify the models of post‐mortem body temperature decrease currently employed in forensic medicine. Twenty‐four hour automatic temperature recordings were performed in four body sites starting 1.25 h after pig killing in an industrial slaughterhouse under typical environmental conditions (19.5–22.5°C). The animals had been randomly selected under a regular manufacturing process. The temperature decrease time plots drawn starting 75 min after death for the eyeball, the orbit soft tissues, the rectum and muscle tissue were found to fit the single‐exponential thermodynamic model originally proposed by H. Rainy in 1868. In view of the actual intersubject variability, the addition of a second exponential term to the model was demonstrated to be statistically insignificant. Therefore, the two‐exponential model for death time estimation frequently recommended in the forensic medicine literature, even if theoretically substantiated for individual test cases, provides no advantage as regards the reliability of estimation in an actual case. The improvement of the precision of time of death estimation by the reconstruction of an individual curve on the basis of two dead body temperature measurements taken 1 h apart or taken continuously for a longer time (about 4 h), has also been proved incorrect. It was demonstrated that the reported increase of precision of time of death estimation due to use of a multiexponential model, with individual exponential terms to account for the cooling rate of the specific body sites separately, is artifactual. The results of this study support the use of the eyeball and/or the orbit soft tissues as temperature measuring sites at times shortly after death. A single‐exponential model applied to the eyeball cooling has been shown to provide a very precise estimation of the time of death up to approximately 13 h after death. For the period thereafter, a better estimation of the time of death is obtained from temperature data collected from the muscles or the rectum.
Enhanced osmotic responsiveness in angiotensin AT1a receptor deficient mice: evidence for a role for AT1b receptors
Authors: Chen Yanfang , Chen Hao , Morris Mariana
Published: June 2005

Experiments were performed to study the role of angiotensin (Ang) AT1a and AT1b receptor subtypes in osmotic regulation of blood pressure using gene deletion and pharmacological methods. The cardiovascular effects of hypertonic saline (HS) or vasopressin (VP) delivered via vascular catheters were measured in Ang AT1a gene deletion (AT1a−/−) and control (AT1a+/+) mice. Blood pressure (BP) and heart rate (HR) were recorded in conscious mice using direct carotid catheters. Plasma osmolality and VP concentration were also measured. The major finding was that deletion of AT1a receptors resulted in enhanced BP response to osmotic stimulation. This was seen after acute HS injection (20 μl, 20% NaCl). The peak percentage change in mean arterial pressure (MAP) was 15.4 ± 1.9%versus 28.1 ± 2.4% (AT1a+/+versus AT1a −/−, respectively). Losartan (AT1 antagonist), but not PD123319 (AT2 antagonist), inhibited the HS‐induced MAP response, specifically in AT1a−/− mice. Plasma osmolality and VP concentration were elevated after HS injection with no differences noted between groups. Vascular injection of VP (5 ng g−1) increased BP and HR, with similar MAP response between groups. Evidence shows that removal of Ang AT1a receptors results in a significant enhancement in the pressor response to acute osmotic stimulation. Studies of AT1 receptor blockade indicate that complementary Ang AT1b receptors, but not AT2 receptors, may be involved in the osmotic response.
Actions of TNF‐α on glutamatergic synaptic transmission in the central nervous system
Authors: Pickering Mark , Cumiskey Derval , O'Connor John J.
Published: June 2005

Increasing attention is being paid to the role of inflammatory and immune molecules in the modulation of central nervous system (CNS) function. Tumour necrosis factor‐α (TNF‐α) is a pro‐inflammatory cytokine, the receptors for which are expressed on neurones and glial cells throughout the CNS. Through the action of its two receptors, it has a broad range of actions on neurones which may be either neuroprotective or neurotoxic. It plays a facilitatory role in glutamate excitotoxicity, both directly and indirectly by inhibiting glial glutamate transporters on astrocytes. Additionally, TNF‐α has direct effects on glutamate transmission, for example increasing expression of AMPA receptors on synapses. TNF‐α also plays a role in synaptic plasticity, inhibiting long‐term potentiation (LTP), a process dependent on p38 mitogen activated kinase (p38 MAP) kinase. In the following review we look at these and other effects of TNF‐α in the CNS.
Helium: Its Synthesis with Elementary Particles from the Deck
Authors: Crompton Nigel E. A. , Patterson Bruce D.
Published: June 2005

This paper describes an educational game—a particle physics Gedanken experiment—where synthesis of helium from elementary particles is performed. The Introduction section presents some of the physics background concerning elementary particles and atomic nuclei. The Material and Methods section explains what is needed for play. The Discussion section describes the rules. Aficionados of the game are welcome to contact the first author with feedback and for a modified version of the rules that also takes the important property of particle spin into consideration.
My Half Hour with Einstein
Authors: Romer Robert H.
Published: June 2005

“So you're studying at Princeton. Would you like to meet Einstein?” That question, during a brief two-body collision at a cocktail party, a collision that was over before I could think of an appropriate response, led—over a year later—to one of the more memorable half hours of my life. It was an elastic collision, we drifted apart, and I thought it had simply been a casual remark until a few days later when the mail brought me a carbon copy [sic] of a letter (dated “25.XII.52”) from the speaker, Dr. Tilly Edinger, to Albert Einstein. Accompanying the letter to Einstein was a card that Dr. Edinger advised me to send around to Einstein's home on Mercer Street to request a meeting. (What is perhaps most truly astonishing in connection with this event is that not only do I still have that carbon copy—and the eventual letter from Mercer Street that invited me to Einstein's home—but that I was able to find both documents in my attic!)
Deconstructing Black Box Aspects of a Computerized Physics Lab
Authors: O'Brien William P.
Published: June 2005

Introductory physics labs increasingly incorporate computers as powerful systems for logging, graphing, and analyzing data (Fig. 1). Situated both physically and conceptually between the external physics experiment and ideas about physics in the mind of the student, such digital systems, composed of electrical technology largely not comprehended by the student, mediate the laboratory process and may function inadvertently to inject an element of unreality and mystery into an otherwise straightforward but challenging experience. The level of mystery can be greatly reduced by briefly postponing the first physics experiment and devoting an entire lab session to a series of guided discussions and simple exercises using the computerized system in conjunction with voltage probes, batteries, and simple transducers to introduce the main features of the digital oscilloscope and establish a simple but workable understanding of the concepts voltage, analog/digital, and sampled data.
Visualization Tool for 3-D Relationships and the Right-Hand Rule
Authors: Nguyen Ngoc-Loan , Meltzer David E.
Published: June 2005

The need to develop an understanding of spatial relationships in three dimensions is one of the major challenges faced by introductory physics students. It arises, for example, when grappling with three-dimensional coordinate systems and with the vector (“cross”) product, when dealing with the concepts of torque and angular momentum, and perhaps most prominently when studying relationships involving magnetic fields and forces. A variety of so-called “right-hand rules” are important and widely used tools for working with such concepts. In this paper we describe a simple and inexpensive visualization tool that may be used to help learn and work with these important rules.
Analysis of Pictures Taken with an Underwater Camera
Authors: Biezeveld Hubert , Elsinga Nienke , Harmsen Floor-Jolijn , Koopman Rose
Published: June 2005

In the Dutch high school system students are required to carry out a research project on a subject of their own choosing. During the section on optics, the teacher (Hubert) mentioned that a fish sees the world above the water in a cone with half-angle equal to the critical angle for the air/water interface (49°). This follows from Snell's law and has been discussed in some detail by Jearl Walker.1 He describes the intersection of this cone with the surface of the water as the “window” through which the fish sees the outside world. A related paper has appeared in this journal.2 Stimulated by the teacher's remark, three students (Nienke, Floor-Jolijn, and Rose) made photographs with an underwater camera in the local swimming pool in Hoorn.
Fan Unit Physics
Authors: Morse Robert A.
Published: June 2005

A lightweight motor-driven propeller mounted on a low-friction cart provides a nearly constant thrust over a moderate range of velocities and can be a powerful pedagogical tool for investigating force and motion. A variety of homemade and commercial versions are now available. This article revisits and extends the topic of fan unit use described earlier.1 It looks at the rationale for use of fan units, gives examples of teaching ideas, and describes construction of two homemade versions of fan units.
An Inexpensive Computer-Controlled Photogate
Authors: Ramey R. Dwayne
Published: June 2005

Budgetary constraints have hit almost every science department, from high schools to community colleges and research universities. While some institutions manage to fully fund their physics laboratories, others are not so fortunate and must do without some modern equipment. One of these conveniences, electronic data devices such as photogates, can greatly facilitate data collection and improve the student's laboratory experience. The photogates themselves are not particularly expensive but require additional hardware and software to connect them to a computer. Though sometimes useful and often convenient, these “black boxes” greatly increase the overall cost of data collection and can place a computer-based physics laboratory out of the reach of many instructors. Though specialized scientific equipment has remained expensive, the price of most other computer-based technology has decreased rapidly. This paper will outline the procedure for creating a “do-it-yourself” photogate system by connecting a purchased photogate directly to a computer. The result is a data collection system whose cost and maintenance is well within reach of most physics labs.
The Effect Surface Temperature Has on Kinetic Friction
Authors: Kauffman Peter , Vondracek Mark
Published: June 2005

Friction is a common force that significantly affects the motion of nearly every moving object we see in everyday life. It is routinely studied and used in the analysis of motion in all levels of high school and college physics classes. In particular, static and kinetic frictions are two types of friction that are defined in commonly used textbooks as: fs,k = μs,k FN, where fs,k is either the static or kinetic friction force, respectively, μs,k is the coefficient of static/kinetic friction, and FN is the normal force. Students are therefore taught that the only quantities that affect static and kinetic friction are the nature of the two materials that are in contact with each other and the force at which the two surfaces press against one another. In this paper we describe a relatively simple experiment that can be done to test the effect surface temperature has on kinetic friction, and that depending on the materials being used, the coefficient of kinetic friction does indeed increase as the surface temperature of one of the materials increases. Because such effects are not normally discussed in standard introductory physics textbooks, this experiment could be used as a nice inquiry activity in introductory physics courses.
An Inquiry Lab on Inclined Planes
Authors: Deters Kelly
Published: June 2005

This paper describes an open-ended inquiry lab exercise dealing with inclined planes that I have used in my introductory high school physics classes. It involves making some simple force and distance measurements, calculating the work done by various forces, analyzing results, and explaining them in a conceptual way. The laboratory exercise is adaptable to various levels of instruction, from guided inquiry and conceptual explanations to complete inquiry with mathematical derivations.
Advice from an Out-of-Field Physics Teacher
Authors: Legleiter Earl
Published: June 2005

Earl Legleiter is a senior science consultant at Mid-continent Research for Education and Learning (McREL) with 23 years of high school physics teaching experience. In 1997 he received the American Association of Physics Teachers Arkansas-Oklahoma-Kansas Section Outstanding High School Physics Teacher award. He was recognized as an American Physical Society Distinguished Physics Teacher in 1999 and was a 1999 national awardee of the prestigious Presidential Award for Excellence in Science.
Measuring Distances with Walkie-Talkies
Authors: Saba Marcelo M. F. , Rosa Rafael Antônio da S.
Published: June 2005

This paper describes how big distances in open areas can be calculated using the speed of sound and a pair of walkie-talkies. This low-cost experiment challenges the students to solve a very common problem and at the same time uses some basic concepts like the speed of sound and of electromagnetic waves. The idea was partly inspired during an outdoor activity with a group of students. The class was divided into two groups, each one working at opposite sides of a lake. We could see each other and communicate using walkie-talkies. Suddenly, a student asked: “How far away do you think they are?” After some guesses and suggesting ideas to find the answer, we realized that we could use walkie-talkies to solve the problem.
Einstein in Western Maryland
Authors: Tam Francis M.
Published: June 2005

Albert Einstein vacationed for two weeks in September 1946 at Deep Creek Lake in western Maryland. It was a well-kept secret. This paper describes his ordinary and yet so extraordinary visit, its historical context, his daily routine, and some interesting stories that reveal his simplicity, humanity, and unique sense of humor.
An Affordable Wireless Microcolor Cam
Authors: Wetherhold Jeffrey M.
Published: June 2005

Readily available low-cost wireless microcolor cam systems are now small enough to mount in or on small toys and they are durable enough to withstand typical radio-controlled airplane crashes. These cams are an invaluable tool for the physics classroom in that they allow students to visually place themselves in the “shoes” of the bodies physics teachers describe and use everyday in the physics classroom.
Understanding Plutonium Production in Nuclear Reactors
Authors: Reed B.Cameron
Published: June 2005

The amount of plutonium produced annually in a nuclear reactor can be estimated based on some simplifying assumptions and knowledge of the relevant reaction cross sections. For a typical commercial nuclear plant, one finds a production rate of about 200 kg/yr, a figure entirely in line with published estimates.
The Baker Street Irregulars Meet Archimedes
Authors: Ritter Thomas J.
Published: June 2005

This paper describes a lab experiment on buoyancy. A plastic garbage bag is filled with helium and fitted loosely into an empty 55-gallon drum. A cardboard piston (Fig. 1) is used to square off the free end of the bag, forming an easily measured right circular cylinder. The gas is at ambient pressure since it is not compressed as it would be in a constricting balloon. Students generally find that the measured lifting force agrees with the theoretical value to within 5%.
Tautochrone as a Harmonic Oscillator
Authors: Sawicki Mikolaj “Mik”
Published: June 2005

A tautochrone is a curve down where a bead will slide to the bottom under the influence of gravity in the same amount of time regardless of where you initially place it. Huygens was first to prove that such a curve is an arc of an inverted cycloid.1
Water in a Coiled Hose
Authors: Lemaire Peter , Waiveris Charles
Published: June 2005

Sometimes things just don't work the way that you think they should. The problem “Coming up Empty,” described in Bet You Can't! Science Impossibilities to Fool You by Vicki Cobb and Kathy Darling is a perfect example.1 In this problem, when water is poured into the top open end of a coiled garden hose, common sense tells us that it should eventually come out of the other end. However, in this case the water will overflow from the top instead of coming out of the other end!
Computerized Physical Pendulum for Classroom Demonstrations
Authors: Kraftmakher Yaakov
Published: June 2005

An inexpensive driven physical pendulum is described for classroom demonstrations, which clearly shows free and forced oscillations, as well as the transient process leading to the steady-state regime of forced oscillations. An advantage of this pendulum is that it is possible to control the decay constant by the use of magnetic braking. A data-acquisition system1 collects the data and displays the oscillations on a computer screen.
Fungal Pathogen Reduces Potential for Malaria Transmission
Authors: Blanford Simon , Chan Brian H. K. , Jenkins Nina , Sim Derek , Turner Ruth J. , Read Andrew F. , Thomas Matt B.
Published: June 2005

Using a rodent malaria model, we found that exposure to surfaces treated with fungal entomopathogens following an infectious blood meal reduced the number of mosquitoes able to transmit malaria by a factor of about 80. Fungal infection, achieved through contact with both solid surfaces and netting for durations well within the typical post-feed resting periods, was sufficient to cause >90% mortality. Daily mortality rates escalated dramatically around the time of sporozoite maturation, and infected mosquitoes showed reduced propensity to blood feed. Residual sprays of fungal biopesticides might replace or supplement chemical insecticides for malaria control, particularly in areas of high insecticide resistance.
An Entomopathogenic Fungus for Control of Adult African Malaria Mosquitoes
Authors: Scholte Ernst-Jan , Ng'habi Kija , Kihonda Japheth , Takken Willem , Paaijmans Krijn , Abdulla Salim , Killeen Gerry F. , Knols Bart G. J.
Published: June 2005

Biological control of malaria mosquitoes in Africa has rarely been used in vector control programs. Recent developments in this field show that certain fungi are virulent to adult
Anopheles
mosquitoes. Practical delivery of an entomopathogenic fungus that infected and killed adult
Anopheles gambiae
, Africa's main malaria vector, was achieved in rural African village houses. An entomological inoculation rate model suggests that implementation of this vector control method, even at the observed moderate coverage during a field study in Tanzania, would significantly reduce malaria transmission intensity.
Rapid Acidification of the Ocean During the Paleocene-Eocene Thermal Maximum
Authors: Zachos James C. , Röhl Ursula , Schellenberg Stephen A. , Sluijs Appy , Hodell David A. , Kelly Daniel C. , Thomas Ellen , Nicolo Micah , Raffi Isabella , Lourens Lucas J. , McCarren Heather , Kroon Dick
Published: June 2005

The Paleocene-Eocene thermal maximum (PETM) has been attributed to the rapid release of ∼2000 × 10
9
metric tons of carbon in the form of methane. In theory, oxidation and ocean absorption of this carbon should have lowered deep-sea pH, thereby triggering a rapid (<10,000-year) shoaling of the calcite compensation depth (CCD), followed by gradual recovery. Here we present geochemical data from five new South Atlantic deep-sea sections that constrain the timing and extent of massive sea-floor carbonate dissolution coincident with the PETM. The sections, from between 2.7 and 4.8 kilometers water depth, are marked by a prominent clay layer, the character of which indicates that the CCD shoaled rapidly (<10,000 years) by more than 2 kilometers and recovered gradually (>100,000 years). These findings indicate that a large mass of carbon (»2000 × 10
9
metric tons of carbon) dissolved in the ocean at the Paleocene-Eocene boundary and that permanent sequestration of this carbon occurred through silicate weathering feedback.
Giant Larvacean Houses: Rapid Carbon Transport to the Deep Sea Floor
Authors: Robison Bruce H. , Reisenbichler Kim R. , Sherlock Rob E.
Published: June 2005

An unresolved issue in ocean science is the discrepancy between the food requirements of the animals living on the deep sea floor and their food supply, as measured by sediment traps. A 10-year time-series study of the water column off Monterey Bay, California, revealed that the discarded mucus feeding structures of giant larvaceans carry a substantial portion of the upper ocean's productivity to the deep seabed. These abundant, rapidly sinking, carbon-rich vectors are not detected by conventional sampling methods and thus have not been included in calculations of vertical nutrient flux or in oceanic carbon budgets.
Photoinduced Plasticity in Cross-Linked Polymers
Authors: Scott Timothy F. , Schneider Andrew D. , Cook Wayne D. , Bowman Christopher N.
Published: June 2005

Chemically cross-linked polymers are inherently limited by stresses that are introduced by post-gelation volume changes during polymerization. It is also difficult to change a cross-linked polymer's shape without a corresponding loss of material properties or substantial stress development. We demonstrate a cross-linked polymer that, upon exposure to light, exhibits stress and/or strain relaxation without any concomitant change in material properties. This result is achieved by introducing radicals via photocleavage of residual photoinitiator in the polymer matrix, which then diffuse via addition-fragmentation chain transfer of midchain functional groups. These processes lead to photoinduced plasticity, actuation, and equilibrium shape changes without residual stress. Such polymeric materials are critical to the development of microdevices, biomaterials, and polymeric coatings.
Observations by the International Tsunami Survey Team in Sri Lanka
Authors: Liu Philip L.-F. , Lynett Patrick , Fernando Harindra , Jaffe Bruce E. , Fritz Hermann , Higman Bretwood , Morton Robert , Goff James , Synolakis Costas
Published: June 2005

In response to the 26 December 2004 tsunami, a survey team of scientists was dispatched to Sri Lanka. Measurements made by the team show that the tsunami elevation and runup ranged from 5 to 12 meters. Eyewitnesses report that up to three separate waves attacked the coast, with the second or third generally the largest. Our conclusion stresses the importance of education: Residents with a basic knowledge of tsunamis, as well as an understanding of how environmental modifications will affect overland flow, are paramount to saving lives and minimizing tsunami destruction.
Microsatellite Instability Generates Diversity in Brain and Sociobehavioral Traits
Authors: Hammock Elizabeth A. D. , Young Larry J.
Published: June 2005

Repetitive microsatellites mutate at relatively high rates and may contribute to the rapid evolution of species-typical traits. We show that individual alleles of a repetitive polymorphic microsatellite in the 5′ region of the prairie vole
vasopressin 1a receptor
(
avpr1a
) gene modify gene expression in vitro. In vivo, we observe that this regulatory polymorphism predicts both individual differences in receptor distribution patterns and socio-behavioral traits. These data suggest that individual differences in gene expression patterns may be conferred via polymorphic microsatellites in the cis-regulatory regions of genes and may contribute to normal variation in behavioral traits.
Resonant Optical Antennas
Authors: Mühlschlegel P. , Eisler H.-J. , Martin O. J. F. , Hecht B. , Pohl D. W.
Published: June 2005

We have fabricated nanometer-scale gold dipole antennas designed to be resonant at optical frequencies. On resonance, strong field enhancement in the antenna feed gap leads to white-light supercontinuum generation. The antenna length at resonance is considerably shorter than one-half the wavelength of the incident light. This is in contradiction to classical antenna theory but in qualitative accordance with computer simulations that take into account the finite metallic conductivity at optical frequencies. Because optical antennas link propagating radiation and confined/enhanced optical fields, they should find applications in optical characterization, manipulation of nanostructures, and optical information processing.
Infrared Echoes near the Supernova Remnant Cassiopeia A
Authors: Krause Oliver , Rieke George H. , Birkmann Stephan M. , Le Floc'h Emeric , Gordon Karl D. , Egami Eiichi , Bieging John , Hughes John P. , Young Erick T. , Hinz Joannah L. , Quanz Sascha P. , Hines Dean C.
Published: June 2005

Two images of Cassiopeia A obtained at 24 micrometers with the Spitzer Space Telescope over a 1-year time interval show moving structures outside the shell of the supernova remnant to a distance of more than 20 arc minutes. Individual features exhibit apparent motions of 10 to 20 arc seconds per year, independently confirmed by near-infrared observations. The observed tangential velocities are at roughly the speed of light. It is likely that the moving structures are infrared echoes, in which interstellar dust is heated by the explosion and by flares from the compact object near the center of the remnant.
Molecular and Cellular Basis of Cardiovascular Gender Differences
Authors: Mendelsohn Michael E. , Karas Richard H.
Published: June 2005

Cardiovascular diseases (CVDs), the major cause of morbidity and mortality for both men and women, occur uncommonly in premenopausal women, but their incidence rises sharply after the menopausal transition. Cardiovascular gender differences are apparent long before CVDs appear in men and women, and improved understanding of the biology underlying these differences has the potential to advance the diagnosis and treatment of CVDs in both sexes. This review considers gender differences in the molecular and cellular physiology of the heart and blood vessels in health and disease, highlighting understudied areas that can help resolve the current controversy regarding hormone replacement therapy and improve cardiovascular health in women.
Uterine Fibroids: The Elephant in the Room
Authors: Walker Cheryl Lyn , Stewart Elizabeth A.
Published: June 2005

Uterine fibroids (leiomyomas) have historically been viewed as important chiefly as the major indication for hysterectomy. As new therapies are developed, the heterogeneity of this disease becomes therapeutically relevant. An awareness of the role of genetics, the extracellular matrix, and hormones in tumor etiology is key to understanding this disease.
HIV/AIDS in Women: An Expanding Epidemic
Authors: Quinn Thomas C. , Overbaugh Julie
Published: June 2005

More than 20 years into the human immunodeficiency virus–type 1 (HIV-1) epidemic, women account for nearly half of the 40 million people living with HIV-1 worldwide, with an even higher proportion existing in developing countries. Social determinants of female vulnerability to HIV-1 include gender disparities, poverty, cultural and sexual norms, lack of education, and violence. Women are also more susceptible to HIV-1 because of hormonal changes, vaginal microbial ecology and physiology, and a higher prevalence of sexually transmitted diseases. Prevention strategies must address the wide range of gender inequalities that promote the dissemination of HIV-1.
Trophic Cascades in a Formerly Cod-Dominated Ecosystem
Authors: Frank Kenneth T. , Petrie Brian , Choi Jae S. , Leggett William C.
Published: June 2005

Removal of top predators from ecosystems can result in cascading effects through the trophic levels below, completely restructuring the food web. Cascades have been observed in small-scale or simple food webs, but not in large, complex, open-ocean ecosystems. Using data spanning many decades from a once cod-dominated northwest Atlantic ecosystem, we demonstrate a trophic cascade in a large marine ecosystem. Several cod stocks in other geographic areas have also collapsed without recovery, suggesting the existence of trophic cascades in these systems.
Addressing Pregnancy Loss
Authors: Aplin John
Published: June 2005

Coming to Term
. Uncovering the Truth About Miscarriage.
By Jon Cohen
. Houghton Mifflin, Boston, 2005.288 pp.$24. ISBN 0-618-27724-2.

Writing for a general audience, Cohen explores medicine's current understanding of miscarriage and an array of available treatments.
ACE2
,
CBK1
, and
BUD4
in Budding and Cell Separation
Authors: Voth Warren P. , Olsen Aileen E. , Sbia Mohammed , Freedman Karen H. , Stillman David J.
Published: June 2005

Mutations in the RAM network genes, including
CBK1
,
MOB2
,
KIC1
,
HYM1
, and
TAO3
, cause defects in bud site selection, asymmetric apical growth, and mating projections. Additionally, these mutants show altered colony morphology, cell separation defects, and reduced
CTS1
expression, phenotypes also seen by mutating the Ace2 transcription factor. We show that an
ACE2
multicopy plasmid suppresses the latter three defects of RAM network mutations, demonstrating that Ace2 is downstream of the RAM network and suggesting that these phenotypes are caused by reduced expression of Ace2 target genes. We show that wild-type W303 strains have a
bud4
mutation and that combining
bud4
with either
ace2
or
cbk1
in haploids results in altered colony morphology. We describe a timed sedimentation assay that allows quantitation of cytokinesis defects and subtle changes in budding pattern and cell shape. Experiments examining budding patterns and sedimentation rates both show that Ace2 and Cbk1 have independent functions in addition to their common pathway in transcription of genes such as
CTS1
.
SWI5
encodes a transcription factor paralogous to
ACE2
. Additive effects are seen in
cbk1 swi5
strains, and we show that activation of some target genes, such as
EGT2
, requires either Swi5 or Ace2 with Cbk1. The relative roles and interactions of Ace2, Cbk1, and Bud4 in bud site selection, polarized growth, and cell separation are discussed.
A Novel Assay for Protein Phosphatase 2A (PP2A) Complexes In Vivo Reveals Differential Effects of Covalent Modifications on Different
Saccharomyces cerevisiae
PP2A Heterotrimers
Authors: Gentry Matthew S. , Li Yikun , Wei Huijun , Syed Farhana F. , Patel Sameer H. , Hallberg Richard L. , Pallas David C.
Published: June 2005

Protein phosphatase 2A (PP2A) catalytic subunit can be covalently modified at its carboxy terminus by phosphorylation or carboxymethylation. Determining the effects of these covalent modifications on the relative amounts and functions of different PP2A heterotrimers is essential to understanding how these modifications regulate PP2A-controlled cellular processes. In this study we have validated and used a novel in vivo assay for assessing PP2A heterotrimer formation in
Saccharomyces cerevisiae
: the measurement of heterotrimer-dependent localization of green fluorescent protein-PP2A subunits. This assay relies on the fact that the correct cellular localization of PP2A requires that it be fully assembled. Thus, reduced localization would occur as the result of the inability to assemble a stable heterotrimer. Using this assay, we determined the effects of PP2A C-subunit phosphorylation mimic mutations and reduction or loss of PP2A methylation on the formation and localization of PP2A
B/Cdc55p
and PP2A
B
′
/Rts1p
heterotrimers. Collectively, our findings demonstrate that phosphorylation and methylation of the PP2A catalytic subunit can influence its function both by regulating the total amount of specific PP2A heterotrimers within a cell and by altering the relative proportions of PP2A
B/Cdc55p
and PP2A
B
′
/Rts1p
heterotrimers up to 10-fold. Thus, these posttranslational modifications allow flexible, yet highly coordinated, regulation of PP2A-dependent signaling pathways that in turn modulate cell growth and function.
Role of Integrase in Reverse Transcription of the
Saccharomyces cerevisiae
Retrotransposon Ty1
Authors: Wilhelm M. , Wilhelm F.-X.
Published: June 2005

Reverse transcriptase (RT) with its associated RNase H (RH) domain and integrase (IN) are key enzymes encoded by retroviruses and retrotransposons. Several studies have implied a functional role of the interaction between IN and RT during the replication of retroviral and retrotransposon genomes. In this study, IN deletion mutants were used to investigate the role of IN on the RT activity of the yeast
Saccharomyces cerevisiae
retrotransposon Ty1. We have identified two domains of Ty1 integrase which have effects on RT activity in vivo. The deletion of a domain spanning amino acid residues 233 to 520 of IN increases the exogenous specific activity of RT up to 20-fold, whereas the removal of a region rich in acidic amino acid residues between residues 521 and 607 decreases its activity. The last result complements our observation that an active recombinant RT protein can be obtained if a small acidic tail mimicking the acidic domain of IN is fused to the RT-RH domain. We suggest that interaction between these acidic amino acid residues of IN and a basic region of RT could be critical for the correct folding of RT and for the formation of an active conformation of the enzyme.
A Rac Homolog Functions Downstream of Ras1 To Control Hyphal Differentiation and High-Temperature Growth in the Pathogenic Fungus
Cryptococcus neoformans
Authors: Vallim Marcelo A. , Nichols Connie B. , Fernandes Larissa , Cramer Kari L. , Alspaugh J. Andrew
Published: June 2005

The
Cryptococcus neoformans
Ras1 protein serves as a central regulator for several signaling pathways. Ras1 controls the induction of the mating pheromone response cascade as well as a distinct signaling pathway that allows this pathogenic fungus to grow at human physiological temperature. To characterize elements of the Ras1-dependent high-temperature growth pathway, we performed a multicopy suppressor screen, identifying genes whose overexpression allows the
ras1
mutant to grow at 37°C. Using this genetic technique, we identified a
C. neoformans
gene encoding a Rac homolog that suppresses multiple
ras1
mutant phenotypes. Deletion of the
RAC1
gene does not affect high-temperature growth. However, a
rac1
mutant strain demonstrates a profound defect in haploid filamentation as well as attenuated mating. In a yeast two-hybrid assay, Rac1 physically interacts with the PAK kinase Ste20, which similarly regulates hyphal formation in this fungus. Similar to Rac1, overexpression of the
STE20α
gene also restores high-temperature growth to the
ras1
mutant. These results support a model in which the small G protein Rac1 acts downstream of Ras proteins and coordinately with Ste20 to control high-temperature growth and cellular differentiation in this human fungal pathogen.
Calcium- and Calcineurin-Independent Roles for Calmodulin in
Cryptococcus neoformans
Morphogenesis and High-Temperature Growth
Authors: Kraus Peter R. , Nichols Connie B. , Heitman Joseph
Published: June 2005

The function of calcium as a signaling molecule is conserved in eukaryotes from fungi to humans. Previous studies have identified the calcium-activated phosphatase calcineurin as a critical factor in governing growth of the human pathogenic fungus
Cryptococcus neoformans
at mammalian body temperature. Here, we employed insertional mutagenesis to identify new genes required for growth at 37°C. One insertion mutant,
cam1-ts
, that displayed a growth defect at 37°C and hypersensitivity to the calcineurin inhibitor FK506 at 25°C was isolated. Both phenotypes were linked to the dominant marker in genetic crosses, and molecular analysis revealed that the insertion occurred in the 3′ untranslated region of the gene encoding the calcineurin activator calmodulin (
CAM1
) and impairs growth at 37°C by significantly reducing calmodulin mRNA abundance. The
CAM1
gene was demonstrated to be essential using genetic analysis of a
CAM1
/
cam1
Δ diploid strain. In the absence of calcineurin function, the
cam1-ts
mutant displayed a severe morphological defect with impaired bud formation. Expression of a calmodulin-independent calcineurin mutant did not suppress the growth defect of the
cam1-ts
mutant at 37°C, indicating that calmodulin promotes growth at high temperature via calcineurin-dependent and -independent pathways. In addition, a Ca
2+
-binding-defective allele of
CAM1
complemented the 37°C growth defect, FK506 hypersensitivity, and morphogenesis defect of the
cam1-ts
mutant. Our findings reveal that calmodulin performs Ca
2+
- and calcineurin-independent and -dependent roles in controlling
C. neoformans
morphogenesis and high-temperature growth.