bluuebunny/crossref_metadata_2025 huggingface dataset:
How spatial structure alters population and community dynamics in a natural plant community
Authors: TURNBULL LINDSAY A. , COOMES DAVID A. , PURVES DREW W. , REES MARK
Published: October 2006

We quantify the effects of spatial structure on individual, population and community biomass within a natural community of annuals for two years (1994 and 1996) in which competition operated differently.

Using field‐parameterized neighbourhood models in which we had previously estimated the spatial scale and magnitude of competitive effects, we perform virtual experiments in which we manipulate spatial structure relative to that observed. We first remove segregation by randomly re‐labelling all annual plants in a focal plant's neighbourhood and then give individuals of all species the same average number of neighbours by re‐locating individuals within the overall pattern of annuals.

The natural spatial structure generally acted to promote species coexistence. In 1994, when the strength of individual‐level competition within species was already greater than that between species, the natural spatial structure enhanced this effect for six out of seven species by increasing the relative frequency of intraspecific contacts. Average plant biomass increased by 0.24–38% when spatial locations were randomized.

In 1996, when a single competitive hierarchy operated, the natural spatial structure systematically benefited small‐seeded, weakly competitive species while having weak negative effects on large‐seeded, strong competitors. Randomizing spatial locations decreased the biomass of the species with the smallest seeds by 12% but increased the biomass of the species with the largest seeds by < 1%. This asymmetry increased dramatically when we used the model to increase the competitive advantage of large seeds artificially. Randomizing spatial locations decreased the biomass of the species with the smallest seeds by 37% but increased the biomass of the species with the largest seeds by only 2.7%.

Effects of spatial structure on total community biomass were always small (maximum 7%). This was because common species always have weak spatial structure, and they draw down the effect on the community as a whole.

Our analysis, for the first time, quantifies the magnitude and direction of the effects of spatial structure in a natural community, and supports the conclusions of theoretical models that spatial structure can have substantial impacts on component species and community dynamics.
Environmental factors of celiac disease: Cytotoxicity of hulled wheat species Triticum monococcum, T. turgidum ssp. dicoccum and T. aestivum ssp. spelta
Authors: Vincentini Olimpia , Maialetti Francesca , Gazza Laura , Silano Marco , Dessi Mariarita , De Vincenzi Massimo , Pogna Norberto Edgardo
Published: October 2006

Background and Aim:  In the present paper, the toxicity of prolamines derived from three cereals with a different genome was investigated in human colon cancer Caco‐2/TC7 and human myelogenous leukemia K562(S) cells. The purpose of this study was to investigate if species from ancient wheat could be considered as healthy food crops devoid or poor in cytotoxic prolamines for celiac disease.

Methods:  Cytotoxicity was measured in terms of inhibition of cell growth, activation of apoptosis, release of nitric oxide (NO), detection of tissue transglutaminase (TG II) and alteration of transepithelial electrical resistance (TEER) on Caco‐2/Tc7 and K562 (S) cell agglutination. Peptic‐tryptic (PT) digest from bread wheat (T. aestivum S. Pastore) was used as a positive control.

Results:  PT digests of prolamins from spelt wheat (T. aestivum ssp. spelta) were found to exert toxic effects on Caco‐2/TC7 cells and to agglutinate K562(S) cells. Increased amounts of NO and TG II expression were observed in Caco‐2/TC7 cells exposed to 1 mg/mL of spelt prolamins, suggesting that spelt wheat can induce cellular mechanisms implicated in the pathogenesis of celiac disease. By contrast, the PT digests from monoccum wheat (Triticum monococcum) and farro wheat (T. turgidum ssp. dicoccum) did not exhibit any negative effects on Caco‐2/TC7 and K562(S) cells.

Conclusions:  The results have shown a constant and significant toxic effect of spelt wheat which is not shared by the two other ancient cereals. Future studies on celiac intestinal organ cultures are needed to increase the prospects of breeding programs aimed at developing wheat cultivars potentially tolerated by most celiac patients.
Long‐term continence after surgery for Hirschsprung's disease
Authors: Catto‐Smith Anthony G , Trajanovska Misel , Taylor Russell G
Published: October 2006

Aim:  Our aim was to examine the long‐term bowel dysfunction that followed surgery for Hirschsprung's disease.

Methods:  Of 414 patients diagnosed with Hirschsprung's disease between 1974 and 2002, 98 were interviewed using a structured questionnaire to provide an assessment of bowel function, medication, diet, physical and social limitations. Forty‐two completed a prospective 4‐week toileting diary and 16 underwent anorectal manometry.

Results:  Four of the 98 patients had permanent stomas and 10 had Down's syndrome. Of the remaining 84 patients (mean age 12 ± 8 years, range 1.9–41.9 years), 13% (11/84) had heavy soiling by day and 17% (14/84) by night. Fifty percent reported episodic urgency, but 36% also reported episodic constipation. Stool consistency was looser in patients with a history of long segment disease. Some aspects of bowel function improved with age. Enuresis was much more frequent than expected. Sixty‐four percent reported adverse reactions to foods, particularly to fruit, vegetables, fats and diary products, and 15% limited their social activities because of fecal incontinence. There were no significant differences in manometric parameters between those patients who soiled and those who did not.

Conclusions:  Fecal incontinence is common after surgery for Hirschsprung's disease and has a significant impact on social activities. Some aspects of bowel function did improve with age. Adverse reactions to food were unexpectedly frequent and need to be further studied.
Twin Data vs. Longitudinal Data to Control for Unobserved Variables in Earnings Functions – Which Are the Differences?*
Authors: Isacsson Gunnar
Published: October 2006

This paper compares two different approaches empirically to control for unobserved characteristics when estimating the effect of marriage on male and female earnings: the longitudinal and the twins approach. The estimates were obtained by exploiting the longitudinal dimension of a large sample of Swedish twins, so that longitudinal and twin‐based estimates could be obtained in the same sample. The two approaches lead to different conclusions both regarding the role of unobserved characteristics in the cross‐sectional earnings–marriage relationship and the effect of marriage on earnings. The paper investigates three potential explanations of this difference.
Telephone follow‐up for patients with amyotrophic lateral sclerosis
Authors: Mannino M. , Cellura E. , Grimaldi G. , Volanti P. , Piccoli F. , La Bella V.
Published: October 2006

The relentless evolution of amyotrophic lateral sclerosis (ALS), a severe neurodegenerative disorder of the upper and lower motoneurons, leads to an increasing level of disability. Most patients, during the course of the disease, become unable to attend the tertiary clinical care center and are thus prevented from enrolling in clinical trials or benefiting from specialized care and management. The main objective of this study was to verify whether the ALS functional rating scale (ALSFRS) could be reliably administered by telephone to patients, when unable to attend the ALS clinic, or to their caregivers. ALSFRS is a validated instrument that assesses the functional status and the disease progression in ALS. We first administered the functional rating scale directly in the clinic to 30 patients, with definite or probable ALS, and to their respective caregivers, and found a very high agreement between the two groups for the total score and the majority of the rating items. Next, we showed, in both patients and caregivers, a high degree of correlation between the total score of the ALSFRS measured by telephone and that reported in the clinic. This indicates that ALSFRS is a reliable instrument for monitoring the disease progression in homebound patients, even when the person contacted by telephone is the caregiver. We also performed a telephone clinic, based on an unstructured interview, with 16 ALS patients at an advanced stage of the disease and unable to attend the ALS clinic. On some occasions, the person interviewed was the caregiver. The symptoms most frequently reported were a worsening of muscle strength, swallowing and breathing problems, constipation, and inability to clear lung secretions. Several patients asked for assistive and adaptive equipment. All patients and caregivers found the telephone clinic very useful and considered it a good complement to the management and care programme.
Isolation and characterization of 13 polymorphic microsatellite loci for the Florida pompano, Trachinotus carolinus
Authors: SEYOUM SEIFU , DENISON STEVEN H. , TRINGALI MICHAEL D.
Published: October 2006

Here we describe 13 polymorphic, dinucleotide microsatellite loci for Trachinotus carolinus (Florida pompano), isolated by using PIMA, a polymerase chain reaction‐based technique. The number of alleles at each locus ranged from 3 to 29 (mean = 11.4) in 45 specimens collected from bay and nearshore waters around St Petersburg, Florida. Levels of expected and observed heterozygosities ranged from 0.15 to 0.94 (mean = 0.69) and from 0.16 to 0.98 (mean = 0.70), respectively. No significant departures from Hardy–Weinberg equilibrium expectations were observed. In exact tests for genotypic disequilibrium, there was no evidence of linkage for any pair of loci. The ability of these markers to cross‐amplify in two congeneric Trachinotus species —T. falcatus (permit) and T. goodei (palometa) — was also assessed. The loci were well‐resolved, highly polymorphic, and independently segregating in these taxa, also suggesting a general utility for intraspecific studies, species identification, and investigation of interspecific hybridization.
Doing Better to Do Good: The Impact of Strategic Adaptation on Nursing Home Performance
Authors: Zinn Jacqueline S. , Mor Vincent , Feng Zhanlian , Intrator Orna
Published: October 2006

Objective.To test the hypothesis that a greater commitment to strategic adaptation, as exhibited by more extensive implementation of a subacute/rehabilitation care strategy in nursing homes, will be associated with superior performance.

Data Sources.Online Survey, Certification, and Reporting (OSCAR) data from 1997 to 2004, and the area resource file (ARF).

Study Design.The extent of strategic adaptation was measured by an aggregate weighted implementation score. Nursing home performance was measured by occupancy rate and two measures of payer mix. We conducted multivariate regression analyses using a cross‐sectional time series generalized estimating equation (GEE) model to examine the effect of nursing home strategic implementation on each of the three performance measures, controlling for market and organizational characteristics that could influence nursing home performance.

Data Collection/Abstraction Methods.OSCAR data was merged with relevant ARF data.

Principal Findings.The results of our analysis provide strong support for the hypothesis.

Conclusions.From a theoretical perspective, our findings confirm that organizations that adjust strategies and structures to better fit environmental demands achieve superior performance. From a managerial perspective, these results support the importance of proactive strategic leadership in the nursing home industry.
Influence of Radial Clearance and Rotor Motion to Hemolysis in a Journal Bearing of a Centrifugal Blood Pump
Authors: Kataoka Hiroyuki , Kimura Yuichi , Fujita Hajime , Takatani Setsuo
Published: October 2006

Abstract:  Hemolysis due to narrow clearance of noncontact bearings is a critical problem for rotary blood pumps. We developed a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing, and found that the hemolysis in the narrow clearance depends not only on the clearance size, but also on the rotor stability. In this study, we quantified the relation between the hemolysis, radial clearance (c), and rotor stability through the measurement of the rotor motion and hemolysis. As a result, it was confirmed that the rotor of the current pump is stabilized within the oscillation of 20 μm in blood, and the hemolysis decreases with increase in the c, which is the opposite in the unstable rotor motion with the previous pump. In order to theoretically discuss this hemolysis tendency, we implemented hemolysis estimation in the c according to hydrodynamics and hemodynamics. This estimation can represent the measured hemolysis tendency, and revealed that the flow rate has large influence on the hemolysis in the c.
Development of a Novel, Remote‐Controlled Artificial Bowel Sphincter Through Microsystems Technology
Authors: Schrag Hans‐J. , Ruthmann Olaf , Doll Alexander , Goldschmidtböing Frank , Woias Peter , Hopt Ulrich T.
Published: October 2006

Abstract:  An artificial sphincter prototype has been developed, specifically designed for comfortable remote control by fecally incontinent patients. The artificial sphincter includes a fluid reservoir, an occlusive cuff, and a micropump based on piezo‐technology in a single unit. Continence and implantation management were evaluated around isolated porcine anal canals and in vivo. The design of the prosthesis reduces the occlusion pressure and allows low inflation volumes (6.5–16 mL). Operating pressures between 24 and 58 mm Hg indicate a minor risk of ischemic injury to the bowel. The operation time is estimated at about 7 days with no recharging of the battery. The novel prototype is a highly integrated prosthesis for placement around the anal canal or lower rectum, effecting continence with comfortable control.
Glucosinolate profile and oviposition behavior in relation to the susceptibilities of Brassicaceae to the cabbage seedpod weevil
Authors: Ulmer B. J. , Dosdall L. M.
Published: October 2006

Understanding how host‐plant characteristics affect behavioral and physiological responses of insect herbivores is of considerable importance in the development of resistant crop germplasm. Feeding, oviposition preference, larval development, and oviposition behavior of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (= Ceutorhynchus assimilis Payk.) (Coleoptera: Curculionidae), were investigated on eight Brassicaceae species that differed in their glucosinolate profiles. The least preferred host plants for feeding and oviposition were the Sinapis alba L. lines while the Brassica carinata L. line was most preferred. Larval development occurred most rapidly on Brassica rapa L. and slowest on S. alba. Larval weight was highest on B. napus L. and lowest on S. alba. Total glucosinolate levels did not influence C. obstrictus larval growth or development; however high levels of specific glucosinolates such as p‐hydroxybenzyl and 3‐butenyl glucosinolate were associated with increased developmental time or reduced weight. The time required for oviposition behavioral events was measured on different host‐plant species: B. rapa, B. napus, B. napus×S. alba, B. tournefortii Gouan., B. juncea (L.) Czern, B. carinata, B. nigra (L.) Koch., and S. alba. The early steps in the sequence were completed faster on more susceptible host plants (B. carinata, B. napus, and B. rapa) than on relatively resistant ones (B. tournefortii and B. juncea). Females explored pods of B. nigra and S. alba, but oviposition occurred only rarely on these species. There was no significant difference in the location on the pod on which oviposition occurred among the different plant species. Mean eggs laid per female weevil were highest on the B. napus×S. alba hybrid and lowest on B. nigra and S. alba.
Down‐regulation of heme oxygenase‐2 is associated with the increased expression of heme oxygenase‐1 in human cell lines
Authors: Ding Yuanying , Zhang Yong Z. , Furuyama Kazumichi , Ogawa Kazuhiro , Igarashi Kazuhiko , Shibahara Shigeki
Published: October 2006

Intracellular heme concentrations are maintained in part by heme degradation, which is catalyzed by heme oxygenase. Heme oxygenase consists of two structurally related isozymes, HO‐1 and HO‐2. Recent studies have identified HO‐2 as a potential oxygen sensor. To gain further insights into the regulatory role of HO‐2 in heme homeostasis, we analyzed the expression profiles of HO‐2 and the biochemical consequences of HO‐2 knockdown with specific short interfering RNA (siRNA) in human cells. Both HO‐2 mRNA and protein are expressed in the eight human cancer cell lines examined, and HO‐1 expression is detectable in five of the cell lines, including HeLa cervical cancer and HepG2 hepatoma. Down‐regulation of HO‐2 expression with siRNA against HO‐2 (siHO‐2) caused induction of HO‐1 expression at both mRNA and protein levels in HeLa and HepG2 cells. In contrast, knockdown of HO‐1 expression did not noticeably influence HO‐2 expression. HO‐2 knockdown prolonged the half‐life of HO‐1 mRNA twofold in HeLa cells. Transient transfection assays in HeLa cells revealed that the 4.5‐kb human HO‐1 gene promoter was activated with selective knockdown of HO‐2 in a sequence‐dependent manner. Moreover, HO‐2 knockdown caused heme accumulation in HeLa and HepG2 cells only when exposed to exogenous hemin. HO‐2 knockdown may mimic a certain physiological change that is important in the maintenance of cellular heme homeostasis. These results suggest that HO‐2 may down‐regulate the expression of HO‐1, thereby directing the co‐ordinated expression of HO‐1 and HO‐2.
Implementation of 3-Port Condensing Wave Rotors in R718 Cycles
Authors: Kharazi Amir A. , Akbari Pezhman , Müller Norbert
Published: October 2006

The use of a novel 3-port condensing wave rotor is suggested to enhance the turbocompression in a refrigeration cycle that works only with water (R718) as a refrigerant. Although the implementation of such a wave rotor essentially reduces the size and cost of R718 units, their efficiency may also be increased. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor, all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure-enthalpy and temperature-entropy diagrams. Based on the described thermodynamic model, a computer program was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.
Planning 3D Well Trajectories Using Cubic Functions
Authors: Sampaio Jorge H. B.
Published: October 2006

This work presents a mathematical method to design complex trajectories for three-dimensional (3D) wells. Three-dimensional cubic trajectories are obtained for various end conditions: free end, set end, free inclination/set azimuth, and set inclination/free azimuth. The resulting trajectories are smooth continuous functions, which better suit the expected performance of modern rotary steerable deviation tools, in particular point-the-bit and push-the-bit systems. A continuous and gradual change in path curvature and tool face results in the smoothest trajectory for 3D wells, that in turn results in lower torque, drag, and equipment wear. The degree of freedom and the associated parameters of the 3D curves express the commitment between the average curvature to the final length of the path, which can be adjusted to fit the design requirements and to optimize the trajectory. Several numerical examples illustrate the various end conditions. The paper also presents the full mathematical results (expressions for the 3D path, actual curvature, and actual tool face). The method is directly applicable to the well planning cycle as well as to automatic and manual hole steering.
Understanding the Behavior of Calcium Compounds in Petroleum Coke Fluidized Bed Combustion (FBC) Ash
Authors: Anthony E. J. , Jia L. , Burwell S. M. , Najman J. , Bulewicz E. M.
Published: October 2006

With growing understanding of the differences between solid residues from the fluidized bed combustion of petroleum coke and of coal, the significance of fuel-derived and sorbent-derived components of the ash has become clearer. It is well documented that hydration of the ashes is necessary prior to disposal or utilization or as a reactivation method. Initially, hydration of the lime was thought to involve water reacting only with CaO to form Ca(OH)2 but when the free lime content of the ashes is looked at before and after hydration, it is apparent that the process is more complex. Detailed analyses have shown that the free lime can decrease and vary within the same ash in different particle size ranges. The complexity of the reactions is reflected in problems with the assessment of the free lime content of the materials and the effect of hydration on different particle size fractions of the ash. The free lime content of the ash is significantly lower than expected based on the elemental analysis. Bed ash from the circulating fluidized bed combustion boilers owned and operated by the Nelson Industrial Steam Company Ltd. (NISCO) was examined in detail to elucidate the fate of calcium in the ash during hydration, using a range of techniques. The objective of the study is to determine the amount of CaO available for hydration/reactivation and to better understand interactions of Ca and other mineral components of the ash. Analysis results indicate that in NISCO ashes up to about 6% of the analytical CaO may be combined as acid soluble and insoluble OCCs (other calcium compounds). This implies up to about 10% less free lime than would be inferred from standard chemical analyses. About 1% of the missing CaO can be present as acid insoluble Ca and Mg vanadates, with up to 2% bound in soluble OCCs. The remaining 3-4% is still not accounted for. It is clear that even very minor quantities of mineral matter, other than CaO or CaSO4, associated mainly with the coarser size fractions, are important. The amount of bound water in the hydrated ash, other than that combined in portlandite or brucite, can be as large as 3-5%. This cannot be ignored when sample mass change on hydration or heating is used as a measure of the extent of CaO to Ca(OH)2 conversion.
Turbulent Lifted Flames in the Hysteresis Regime and the Effects of Coflow
Authors: Terry S. D. , Lyons K. M.
Published: October 2006

A study of the characteristics of turbulent lifted-jet flames in the hysteresis regime was performed using methane and ethylene fuels in laminar and turbulent air coflows. Reattachment velocities and lifted flame heights just prior to reattachment vary linearly as for laminar flames in coflow. The flow regime of the coflow (i.e., laminar or turbulent) did not appear to affect the behavior of these flames. These observations are of utility in designing maximum turndown burners in air coflow, especially for determining stability criteria in low fuel-flow applications.
Experimental Separation of Sensory and Motor Functions in Pea Tendrils
Authors: Jaffe M. J.
Published: October 2006

When illuminated pea tendrils from light-grown plants are rubbed on their abaxial side, they rapidly coil in a spiral fashion. If similar tendrils are held in the dark for 3 days and then rubbed, however, they will not coil until they are subsequently illuminated. They can remain uncoiled in the dark for as long as 2 hours after stimulation, and will still coil immediately when they are illuminated. Tendrils that are rubbed and held at 25°C will coil, but those treated at 5° or 10°C will not. However, tendrils rubbed at 25°C and kept from coiling for an hour at 5°C, will immediately coil when restored to the higher temperature. These observations are interpreted to imply separation of sensory and motor functions.
California Current Eddy Formation: Ship, Air, and Satellite Results
Authors: Bernstein Robert L. , Breaker Larry , Whritner Robert
Published: October 2006

Until recently, quantitative measurements of the circulation of the California Current were limited to hydrographic determinations of temperature and salinity. This information is now being augmented by satellite data. Clouds permitting, satellite scanner systems can locate major ocean frontal boundaries if they are associated with even quite weak horizontal sea-surface temperature gradients. The satellite data are most usefully interpreted in a region such as that encompassing the California Current, where the surface and main thermocline temperature distributions bear some relation to each other. In such a region, it is possible to make interpretations of circulation based on satellite-derived sea-surface temperature patterns. The correctness of these interpretations depends heavily on the availability of historical and present-day subsurface data, collected by conventional methods from ships and aircraft. Satellite infrared scanners, in addition to providing information on circulation with vastly increased spatial resolution, have the potential (with cooperative weather) for providing increased time resolution. These improvements in resolution have permitted us to see that much of the spatial variation in the California Current takes place along well-defined fronts and to observe the evolution of one particular meander.
Anthropogenic CO Emissions: Implications for the Atmospheric CO-OH-CH
4
Cycle
Authors: Sze Nien Dak
Published: October 2006

Present anthropogenic emissions of CO are apparently large enough to perturb the natural CO-OH-CH
4
cycle, which plays a crucial role in the self-cleansing processes in the troposphere. A significant increase in global concentrations of CO, CH
4
, CH
3
Cl, and other trace gases may result from a decrease in the OH concentration caused by continued CO emissions. Even if the CO emissions were maintained at the present rate, increases in CO and CH
4
by the year 2025 might be as large as 50 and 25 percent, respectively. The time constants associated with the perturbations of the CO-OH-CH
4
cycle are of the order of a few decades. Perturbation of this cycle may also indirectly affect stratospheric chemistry.
The Convergence of Computing and Telecommunications Systems
Authors: Farber David , Baran Paul
Published: October 2006

Since we do not know of any completely workable solutions to the problems we have considered, we shall settle for a few general observations:

1) The public availability of socially useful computer communications services is and has been held back by legal battles that are now under way between the potential suppliers.

2) No simple resolution of these issues in the near future seems likely in view of the past conceptual separation of computers and communications doctrines.

3) The current policy is to determine whether the nation shall or shall not have certain computer communications services, by the adversary process. In this process, often only the voices of the loudest adversary suppliers are heard.

4) Although there can be no certainty that better alternatives cannot be devised, we believe that such a possibility assumes a higher probability if the key actors come from the technical community sectors more representative of the future consumers.

5) If we are to have the new services that are possible, we need an approach that makes better use of the technologists' dreams and goals rather than have future prospects excessively bound by lawyers paid to preserve the interests of their clients, irrespective of any secondary consequences.

6) We cannot be sanguine about this possibility, as technological statesmanship is too easily corrupted by the same forces that have placed us in this predicament. Furthermore, even if not corrupted, beneficial cooperation can too readily be regarded as simply collusion.

7) Although we do not have any clear answer, we do know that present approaches are not taking us where we want to go very rapidly and that alternative approaches should at least be considered.
Physical Limits in Semiconductor Electronics
Authors: Keyes Robert W.
Published: October 2006

Although the limitations of the methods of lithography in use at a particular time are easily recognized and attract substantial attention, experience shows that technological ingenuity keeps pushing them to ever-smaller dimensions. There seems to be no fundamental reason to expect that lithographic limits will not continue to recede. The limits to the advance of miniaturization are to be found in the ability of materials to withstand high electric fields and in the ability of packaging technology to remove heat from active components and provide for power distribution, signal interconnection, and flexible mechanical assembly.
Sunlight-Induced Bromate Formation in Chlorinated Seawater
Authors: Macalady Donald L. , Carpenter James H. , Moore Cynthia A.
Published: October 2006

Chlorinated waters are being introduced into estuarine and coastal areas in increasing quantities. In such systems, the chlorine reacts with the natural bromide and ammonia to produce the highly toxic hypobromous acid, hypobromite ion, and haloamines. Sunlight causes up to 50 percent conversion to bromate ion, which is persistent in natural waters and has an unknown toxicity.
Ribulose Bisphosphate Carboxylase: A Two-Layered, Square-Shaped Molecule of Symmetry 422
Authors: Baker Timothy S. , Eisenberg David , Eiserling Frederick
Published: October 2006

Electron micrographs and x-ray diffraction patterns of crystals of ribulose bisphosphate carboxylase, probably the most abundant protein on earth, have provided new details of the arrangement of subunits. The eight large subunits and eight small subunits are clustered in two layers, perpendicular to a fourfold axis of symmetry. Viewed down the fourfold axis, the molecule is square-shaped.
Head Capsule Transmission of Long-Wavelength Light in the Curculionidae
Authors: Meyer John R.
Published: October 2006

The head capsule of many weevils contains a region that transmits only far-red and near-infrared light. In the alfalfa weevil,
Hypera postica
, this extraocular cutoff filter evidently works in conjunction with the compound eyes, enabling the insect to use visual cues in locating or recognizing its host plant.
Geomorphic Degradations on the Surface of Venus: An Analysis of Venera 9 and Venera 10 Data
Authors: Florensky C. P. , Ronca L. B. , Basilevsky A. T.
Published: October 2006

On the basis of the physical and chemical measurements made on the surface of Venus and transmitted back to Earth by the Soviet automatic landers Venera 9 and Venera 10, a geomorphically inactive environment should be expected. An analysis of the television photographs reveals, however, that at least two processes of degradation occur. One operates on a scale of decimeters to meters and is responsible for the fracturing of a layered source rock and the subsequent downslope movement of the fragments. Mass-wasting, perhaps activated by venusian quakes or by unknown geological processes, is likely to be the agent. Another geomorphic degradation process occurs on the scale of a centimeter or less and is responsible for the rounding of edges and the pitting of rock surfaces. The agents of this process are not known, but atmospheric action, perhaps in connection with volcanic episodes, may be the cause. From a geomorphic point of view, the landscape of the Venera 9 landing site can be considered young and that of the Venera 10 landing site, mature.
Flavonoids and Other Chemical Constituents of Fossil Miocene
Zelkova
(Ulmaceae)
Authors: Niklas Karl J. , Giannasi David E.
Published: October 2006

Organic solvent extractions of
Zelkova oregoniana, a
Miocene angiosperm compression fossil, indicate the chemical preservation of kaempferol, dihydrokaempferol, an
n-
alkane chain length range of 10 to 32 carbons, hydroxy acids, steranes, triterpenoids, and methyl pheophorbide a. This appears to be the oldest occurrence of flavonoids in fossil sediments reported
.
The Photosynthetic Unit of Hydrogen Evolution
Authors: Greenbaum Elias
Published: October 2006

A study of the absolute photoproduction of hydrogen by autotrophically grown
Chlorella vulgaris
with single-turnover flashes of light indicates that (i) while the Emerson and Arnold photosynthetic unit has the value chlorophyll : oxygen ≈ 1700 : 1, the hydrogen analog of this unit has the value chlorophyll : hydrogen ≈ 1400 : 1, and (ii) whereas the yield of oxygen from dark-adapted algal cells is zero on the first flash and then undergoes damped oscillations of period 4 about the steady-state value, the corresponding yield of hydrogen is fixed at the steady-state value from the first flash onward. These observations suggest that in the molecular mechanism of photosynthetic hydrogen evolution (i) the light reaction is at least 60 percent as efficient as the corresponding oxygen evolution reaction as measured by the ability to utilize absorbed visible quanta, and (ii) there are no sequential, photoproduced, metastable intermediates as there are in the case of oxygen evolution. Therefore, a minimum of two reducing equivalents from two different photosystems must have access to a common pool in producing molecular hydrogen if these photosystems each produce one electron per single-turnover flash.
Allelopathic Influence on Blue-Green Bloom Sequence in a Eutrophic Lake
Authors: Keating Kathleen Irwin
Published: October 2006

The bloom sequence in a eutrophic lake, Linsley Pond, over a period of 3 years is correlated to the effects of cell-free filtrates of dominant blue-green algae on both their successors and their predecessors. There is unbroken correspondence between the effects of heat-labile probiotic and antibiotic filtrates and the rise and fall of bloom populations in situ. All organisms in vitro were axenic or unialgal (bacterized) isolates from Linsley Pond.
Glass Hydration: A Method of Dating Glass Objects
Authors: Lanford William A.
Published: October 2006

A new nondestructive method for dating or authenticating man-made glass is proposed, and the initial results of an exploration of the potential of this method are presented. The method is based on a relation between the age of a glass object and the thickness of the layer of hydrated glass on its surface, with the thickness of this hydrated surface layer being measured by means of the
15
N nuclear resonance depth profiling technique. A qualitative age scale is established for some common 19th- and 20th-century American glass.
Retention of Plutonium and Americium by Rock
Authors: Fried Sherman , Friedman Arnold M. , Atcher Robert , Hines John
Published: October 2006

The relative migration ratio of plutonium in various rocks is approximately 100 micrometers per meter of water flow; the corresponding migration ratio for americium is about 500 micrometers per meter of water flow. Under these conditions radioactive decay will have taken place to such an extent that little plutonium and americium can reach the external environment from a well-designed and isolated geological repository site.
Meteorite Impact Crater Discovered in Central Alaska with Landsat Imagery
Authors: Cannon P. Jan
Published: October 2006

Several supporting observations indicate that Sithylemenkat Lake, Alaska; occupies a meteorite impact crater formed near the end of the Wisconsinan glaciation. The initial identification with Landsat imagery is attributed to the unique perspective provided by such imagery.
Anoxic, Hypersaline Basin in the Northern Gulf of Mexico
Authors: Shokes Robert F. , Trabant Peter K. , Presley Bob J. , Reid David F.
Published: October 2006

A 400-square-kilometer depression in the continental slope of the northern Gulf of Mexico (approximately 27°N, 91°W) has been found to contain anoxic, hypersaline (∼250 grams per kilogram) water in the bottom 200 meters. The interface between the brine and overlying seawater acts as a midwater seismic reflector similar to those seen in the Red Sea. The bulk chemical composition of the brine is similar to that from the Red Sea, but differences between the two in both heat content and geomorphological setting indicate different modes of origin.
Atomic Chlorine and the Chlorine Monoxide Radical in the Stratosphere: Three in situ Observations
Authors: Anderson J. G. , Margitan J. J. , Stedman D. H.
Published: October 2006

Three simultaneous observations of atomic chlorine (Cl) and the chlorine monoxide radical (ClO) are reported which encompass the altitude interval between 25 and 45 kilometers. Together, Cl and ClO form a gas-phase catalytic cycle potentially capable of depleting stratospheric ozone. Observed Cl and ClO densities, although variable, imply that chlorine compounds constitute an important part of the stratospheric ozone budget. The results are compared with recent models of stratospheric photochemistry which have been used as a basis for predicting ozone depletion resulting from fluorocarbon release.
Uranus: The Rings Are Black
Authors: Sinton William M.
Published: October 2006

An upper limit of 0.05 is established for the geometric albedo of the newly discovered rings of Uranus. In view of this very low albedo, the particles of the rings cannot be ice-covered as are those of rings A and B of Saturn.
Pharmacokinetic Considerations and Efficacy of Levofloxacin in an Inhalational Anthrax (Postexposure) Rhesus Monkey Model
Authors: Kao L. Mark , Bush Karen , Barnewall Roy , Estep James , Thalacker Frederic W. , Olson Pamela H. , Drusano George L. , Minton Neil , Chien Shuchean , Hemeryck Alex , Kelley Michael F.
Published: October 2006

Because the treatment of inhalational anthrax cannot be studied in human clinical trials, it is necessary to conduct efficacy studies using a rhesus monkey model. However, the half-life of levofloxacin was approximately three times shorter in rhesus monkeys than in humans. Computer simulations to match plasma concentration profile, area under the concentration-time curve (AUC), and time above MIC for a human oral dose of 500 mg levofloxacin once a day identified a dosing regimen in rhesus monkeys that would most closely match human exposure: 15 mg/kg followed by 4 mg/kg administered 12 h later. Approximately 24 h following inhalational exposure to approximately 49 times the 50% lethal doses of
Bacillus anthracis
(Ames strain), monkeys were treated daily with vehicle, levofloxacin, or ciprofloxacin for 30 days. Ciprofloxacin was administered at 16 mg/kg twice a day. Following the 30-day treatment, monkeys were observed for 70 days. Nine of 10 control monkeys died within 9 days of exposure. No clinical signs were observed in fluoroquinolone-treated monkeys during the 30 treatment days. One monkey died 8 days after levofloxacin treatment, and two monkeys from the ciprofloxacin group died 27 and 36 days posttreatment, respectively. These deaths were probably related to the germination of residual spores.
B. anthracis
was positively cultured from several tissues from the three fluoroquinolone-treated monkeys that died. MICs of levofloxacin and ciprofloxacin from these cultures were comparable to those from the inoculating strain. These data demonstrate that a humanized dosing regimen of levofloxacin was effective in preventing morbidity and mortality from inhalational anthrax in rhesus monkeys and did not select for resistance.
Synergism between β-Lactams and Glycopeptides against VanA-Type Methicillin-Resistant
Staphylococcus aureus
and Heterologous Expression of the
vanA
Operon
Authors: Périchon Bruno , Courvalin Patrice
Published: October 2006

Vancomycin resistance of
Staphylococcus aureus
NY-VRSA and VRSA-5 is due to acquisition of a
vanA
operon located in a Tn
1546
-like element. The
vanA
gene cluster of NY-VRSA contained one copy of insertion sequences IS
1251
and IS
1216V
relative to that of VRSA-5. As evidenced by the nature of the late peptidoglycan precursors and by quantification of
d
,
d
-peptidase activities, the vancomycin resistance genes were efficiently expressed in both strains. Study of the stability and inducibility of glycopeptide resistance suggested that low-level glycopeptide resistance of NY-VRSA was most probably due to plasmid instability combined with a long delay for resistance induction. The activity of combinations of vancomycin or teicoplanin with oxacillin against the four VanA-type
S. aureus
strains already reported was tested by single and double disk diffusion, E-test on agar alone or supplemented with antibiotics, the checkerboard technique, and by determining time-kill curves. A strong synergism against the four clinical isolates, with fractional inhibitory concentration indexes from 0.008 to 0.024, was reproducibly observed between the two antibiotics by all methods. These observations indicate that cell wall inhibitors of the β-lactam and glycopeptide classes exert strong and mutual antagonistic effects on resistance to each other against VanA-type methicillin-resistant
S. aureus
.
In Vitro Metacestodicidal Activities of Genistein and Other Isoflavones against
Echinococcus multilocularis
and
Echinococcus granulosus
Authors: Naguleswaran Arunasalam , Spicher Martin , Vonlaufen Nathalie , Ortega-Mora Luis M. , Torgerson Paul , Gottstein Bruno , Hemphill Andrew
Published: October 2006

Echinococcus multilocularis
and
Echinococcus granulosus
metacestode infections in humans cause alveolar echinococcosis and cystic echinococcosis, respectively, in which metacestode development in visceral organs often results in particular organ failure. Further, cystic hydatidosis in farm animals causes severe economic losses. Although benzimidazole derivatives such as mebendazole and albendazole are being used as therapeutic agents, there is often no complete recovery after treatment. Hence, in searching for novel treatment options, we examined the in vitro efficacies of a number of isoflavones against
Echinococcus
metacestodes and protoscoleces. The most prominent isoflavone, genistein, exhibits significant metacestodicidal activity in vitro. However, genistein binds to the estrogen receptor and can thus induce estrogenic effects, which is a major concern during long-term chemotherapy. We have therefore investigated the activities of a number of synthetic genistein derivatives carrying a modified estrogen receptor binding site. One of these, Rm6423, induced dramatic breakdown of the structural integrity of the metacestode germinal layer of both species within 5 to 7 days of in vitro treatment. Further, examination of the culture medium revealed increased leakage of parasite proteins into the medium during treatment, but zymography demonstrated a decrease in the activity of metalloproteases. Moreover, two of the genistein derivatives, Rm6423 and Rm6426, induced considerable damage in
E. granulosus
protoscoleces, rendering them nonviable. These findings demonstrate that synthetic isoflavones exhibit distinct in vitro effects on
Echinococcus
metacestodes and protoscoleces, which could potentially be exploited further for the development of novel chemotherapeutical tools against larval-stage
Echinococcus
infection.
Natural Variation Can Significantly Alter the Sensitivity of Influenza A (H5N1) Viruses to Oseltamivir
Authors: Rameix-Welti M. A. , Agou F. , Buchy P. , Mardy S. , Aubin J. T. , Véron M. , van der Werf S. , Naffakh N.
Published: October 2006

Geographic spread of highly pathogenic avian H5N1 influenza viruses may give rise to an influenza pandemic. During the first months of a pandemic, control measures would rely mainly on antiviral drugs, such as the neuraminidase (NA) inhibitors oseltamivir and zanamivir. In this study, we compare the sensitivities to oseltamivir of the NAs of several highly pathogenic H5N1 viruses isolated in Asia from 1997 to 2005. The corresponding 50% inhibitory concentrations were determined using a standard in vitro NA inhibition assay. The

K
m

for the substrate and the affinity for the inhibitor (

K
i

) of NA were determined for a 1997 and a 2005 virus, using an NA inhibition assay on cells transiently expressing the viral enzyme. Our data show that the sensitivities of the NAs of H5N1 viruses isolated in 2004 and 2005 to oseltamivir are about 10-fold higher than those of earlier H5N1 viruses or currently circulating H1N1 viruses. Three-dimensional modeling of the N1 protein predicted that Glu248Gly and Tyr252His changes could account for increased sensitivity. Our data indicate that genetic variation in the absence of any drug-selective pressure may result in significant variations in sensitivity to anti-NA drugs. Although the clinical relevance of a 10-fold increase in the sensitivity of NA to oseltamivir needs to be investigated further, the possibility that sensitivity to anti-NA drugs could increase (or possibly decrease) significantly, even in the absence of treatment, underscores the need for continuous evaluation of the impact of genetic drift on this parameter, especially for influenza viruses with pandemic potential.
DNA Methylase Activity as a Marker for the Presence of a Family of Phage-Like Elements Conferring Efflux-Mediated Macrolide Resistance in Streptococci
Authors: Figueiredo T. A. , Aguiar S. I. , Melo-Cristino J. , Ramirez M.
Published: October 2006

Recently, two related chimeric genetic elements (Tn
1207.3
and Φ10394.4) were shown to carry the macrolide efflux gene
mef
in
Streptococcus pyogenes
(group A streptococci [GAS]). The dissemination of elements belonging to the Tn
1207.3
/Φ10394.4 family in recent isolates of GAS,
Streptococcus dysgalactiae
subsp.
equisimilis
,
Streptococcus pneumoniae
, and
Streptococcus agalactiae
recovered in Portugal was surveyed. In total, 149 GAS, 18
S. pneumoniae
, 4
S. dysgalactiae
subsp.
equisimilis
, and 5
S. agalactiae
isolates from infections, presenting the M phenotype of macrolide resistance and containing the
mef
gene, were screened for the presence of Tn
1207.3
/Φ10394.4 by PCR targeting open reading frames (ORFs) specific for these related elements. All the GAS isolates tested and one of the
S. dysgalactiae
subsp.
equisimilis
isolates carried Tn
1207.3.
However, neither of these elements was found in the isolates of the other streptococcal species. It was also noted that the DNAs of the isolates carrying Tn
1207.3
were resistant to cleavage by the endonuclease SmaI. Cloning and expression of ORF12 of Tn
1207.3
in
Escherichia coli
showed that it encoded a methyltransferase that rendered DNA refractory to cleavage by SmaI (M.Spy10394I). Using this characteristic as a marker for the presence of the Tn
1207.3
/Φ10394.4 family, we reviewed the literature and concluded that these genetic elements are widely distributed among tetracycline-susceptible GAS isolates presenting the M phenotype from diverse geographic origins and may have played an important role in the dissemination of macrolide resistance in this species.
Tissue engineering for tendon repair
Authors: Bagnaninchi Pierre-Olivier , Yang Ying , El Haj Alicia J , Maffulli Nicola
Published: October 2006

Tissue engineering aims to induce tissue self-regeneration in vivo or to produce a functional tissue replacement in vitro to be then implanted in the body. To produce a viable and functional tendon, a uniaxially orientated collagen type I matrix has to be generated. Biochemical and physical factors can potentially alter both the production and the organisation of this matrix, and their combination in a dose- and time-dependent manner is probably the key to in vitro engineered tendons. This review discusses the role of these different factors affecting tenocyte growth in a three-dimensional environment in vivo and in vitro, and underlines the future challenge of tendon tissue engineering.