bluuebunny/crossref_metadata_2025 huggingface dataset:
Bending for love: losses and gains of sexual dimorphisms are strictly correlated with changes in the mounting position of sepsid flies (Sepsidae: Diptera)
Authors: Puniamoorthy Nalini , Su Kathy Feng-Yi , Meier Rudolf
Published: May 2008

Background

Sexually dimorphic structures contribute the largest number of morphological differences between closely related insect species thus implying that these structures evolve fast and are involved in speciation. The current literature focuses on the selective forces that drive these changes, be it 'sexual conflict' or 'female choice'. However, there are only few studies examining the function of sexual dimorphisms and even fewer that investigate how functional changes influence dimorphisms. This is largely due to the paucity of taxa for which the morphology, behavior, and phylogenetic relationships for multiple species are known. Here we present such data for sepsid flies. Sepsids have starkly dimorphic forelegs whose function can be documented under laboratory conditions. We use data from 10 genes to reconstruct the phylogenetic relationships for 33 species and test whether mounting positions are correlated with the presence and absence of sexual dimorphisms in the forelegs.

Results

The phylogenetic tree fully resolves the relationship with 29 of the 31 nodes of the tree having a posterior probability of 1.0. Twenty-eight of the 31 sepsid species have sexually dimorphic forelegs. All 28 species with such forelegs have the same mounting technique whereby the male uses his modified forelegs to grasp the female wingbase. Mapping mounting behavior and foreleg morphology onto the tree reveals that the wing grasp evolved once and was reduced twice. All changes in the mounting behavior are strictly and statistically significantly correlated with the origin and losses of sexually dimorphic legs (concentrated changes test: P < 0.001); i.e., the two species that have independently lost the wing grasp have both also re-evolved monomorphic legs. The wing grasp in these species is replaced with a novel but very similar mounting technique not involving the forelegs: the males bend their abdomens forward and directly establish genital contact to the female. In addition, one of the secondarily monomorphic species, Sepsis secunda, has evolved a new sexual dimorphism, a 'bump' on the dorsal side of the 4th tergite, which is now touching the ventral side of the female abdomen.

Conclusion

Our study reveals that the evolution of sexually dimorphic legs in Sepsidae can only be understood once the function of the legs during mating is considered and the relationships of species with and without sexual dimorphisms are known. We demonstrate that homoplasy in sexually dimorphic structures can be due to homoplasy in mating behavior. We furthermore document that the two species with secondarily monomorphic legs have independently replaced the typical sepsid wing grasp with very similar, new mounting techniques. This suggests that convergent evolution may be common in mating behaviors.
The estrogen hypothesis of Schizophrenia implicates glucose metabolism: Association study in three independent samples
Authors: Olsen Line , Hansen Thomas , Jakobsen Klaus D , Djurovic Srdjan , Melle Ingrid , Agartz Ingrid , Hall Haakan , Ullum Henrik , Timm Sally , Wang August G , Jönsson Erik G , Andreassen Ole A , Werge Thomas
Published: May 2008

Background

Schizophrenia is a highly heritable complex psychiatric disorder with an underlying pathophysiology that is still not well understood. Metaanalyses of schizophrenia linkage studies indicate numerous but rather large disease-associated genomic regions, whereas accumulating gene- and protein expression studies have indicated an equally large set of candidate genes that only partially overlap linkage genes. A thorough assessment, beyond the resolution of current GWA studies, of the disease risk conferred by the numerous schizophrenia candidate genes is a daunting and presently not feasible task. We undertook these challenges by using an established clinical paradigm, the estrogen hypothesis of schizophrenia, as the criterion to select candidates among the numerous genes experimentally implicated in schizophrenia. Bioinformatic tools were used to build and priorities the signaling networks implicated by the candidate genes resulting from the estrogen selection. We identified ten candidate genes using this approach that are all active in glucose metabolism and particularly in the glycolysis. Thus, we tested the hypothesis that variants of the glycolytic genes are associated with schizophrenia or at least with gender-associated aspects of the illness.

Results

We genotyped 185 SNPs in three independent case-control samples of Scandinavian origin (a total of 765 patients and 1274 control subjects). Variants of the mitogen-activated protein kinase 14 gene (MAPK14) and the phosphoenolpyruvate carboxykinase 1 (PCK1) and fructose-1,6-biphosphatase (FBP1) were nominal significantly associated with schizophrenia, and several haplotypes within enolase 2 gene (ENO2) consist of the same SNP allele having elevated risk of schizophrenia. Importantly, we find no evidence of stratification due to nationality or gender.

Conclusion

Several gene variants in the Glycolysis were associated with schizophrenia in three independent samples. However, the findings are weak and not resistant to correction for multiple testing, which may indicate that they are either spurious or may relate to a particular subtype or aspect of the illness.
Escalating Plasmodium falciparum antifolate drug resistance mutations in Macha, rural Zambia
Authors: Mkulama Mtawa AP , Chishimba Sandra , Sikalima Jay , Rouse Petrica , Thuma Philip E , Mharakurwa Sungano
Published: May 2008

Background

In Zambia the first-line treatment for uncomplicated malaria is artemisinin combination therapy (ACT), with artemether-lumefantrine currently being used. However, the antifolate regimen, sulphadoxine-pyrimethamine (SP), remains the treatment of choice in children weighing less than 5 kg and also in expectant mothers. SP is also the choice drug for intermittent preventive therapy in pregnancy and serves as stand-by treatment during ACT stock outs. The current study assessed the status of Plasmodium falciparum point mutations associated with antifolate drug resistance in the area around Macha.

Methods

A representative sample of 2,780 residents from the vicinity of Macha was screened for malaria by microscopy. At the same time, blood was collected onto filter paper and dried for subsequent P. falciparum DNA analysis. From 188 (6.8%) individuals that were thick film-positive, a simple random sub-set of 95 P. falciparum infections were genotyped for DHFR and DHPS antifolate resistance mutations, using nested PCR and allele-specific restriction enzyme digestion.

Results

Plasmodium falciparum field samples exhibited a high prevalence of antifolate resistance mutations, including the DHFR triple (Asn-108 + Arg-59 + Ile-51) mutant (41.3%) and DHPS double (Gly-437 + Glu-540) mutant (16%). The quintuple (DHFR triple + DHPS double) mutant was found in 4 (6.5%) of the samples. Levels of mutated parasites showed a dramatic escalation, relative to previous surveys since 1988. However, neither of the Val-16 and Thr-108 mutations, which jointly confer resistance to cycloguanil, was detectable among the human infections. The Leu-164 mutation, associated with high grade resistance to both pyrimethamine and cycloguanil, as a multiple mutant with Asn-108, Arg-59 and (or) Ile-51, was also absent.

Conclusion

This study points to escalating levels of P. falciparum antifolate resistance in the vicinity of Macha. Continued monitoring is recommended to ensure timely policy revisions before widespread resistance exacts a serious public health toll.
Glucagon-like peptide 1 receptor stimulation reverses key deficits in distinct rodent models of Parkinson's disease
Authors: Harkavyi Alexander , Abuirmeileh Amjad , Lever Rebecca , Kingsbury Ann E , Biggs Christopher S , Whitton Peter S
Published: May 2008

Background

It has recently become apparent that neuroinflammation may play a significant role in Parkinson's disease (PD). This is also the case in animal paradigms of the disease. The potential neuroprotective action of the glucagon-like peptide 1 receptor (GLP-1R) agonist exendin-4 (EX-4), which is protective against cytokine mediated apoptosis and may stimulate neurogenesis, was investigated In paradigms of PD.

Methods

Two rodent 'models' of PD, 6-hydroxydopamine (6-OHDA) and lipopolysaccaride (LPS), were used to test the effects of EX-4. Rats were then investigated in vivo and ex vivo with a wide range of behavioural, neurochemical and histological tests to measure integrity of the nigrostriatal system.

Results

EX-4 (0.1 and 0.5 μg/kg) was given seven days after intracerebral toxin injection. Seven days later circling behaviour was measured following apomorphine challenge. Circling was significantly lower in rats given EX-4 at both doses compared to animals given 6-OHDA/LPS and vehicle. Consistent with these observations, striatal tissue DA concentrations were markedly higher in 6-OHDA/LPS + EX-4 treated rats versus 6-OHDA/LPS + vehicle groups, whilst assay of L-DOPA production by tyrosine hydroxylase was greatly reduced in the striata of 6-OHDA/LPS + vehicle rats, but this was not the case in rats co-administered EX-4. Furthermore nigral TH staining recorded in 6-OHDA/LPS + vehicle treated animals was markedly lower than in sham-operated or EX-4 treated rats. Finally, EX-4 clearly reversed the loss of extracellular DA in the striata of toxin lesioned freely moving rats.

Conclusion

The apparent ability of EX-4 to arrest progression of, or even reverse nigral lesions once established, suggests that pharmacological manipulation of the GLP-1 receptor system could have substantial therapeutic utility in PD. Critically, in contrast to other peptide agents that have been demonstrated to possess neuroprotective properties in pre-clinical models of PD, EX-4 is in current clinical use in the management of type-II diabetes and freely crosses the blood brain barrier; hence, assessment of the clinical efficacy of EX-4 in patients with PD could be pursued without delay.
GALA: an international multicentre randomised trial comparing general anaesthesia versus local anaesthesia for carotid surgery
Authors: Gough Michael J , Bodenham Andrew , Horrocks Michael , Colam Bridget , Lewis Steff C , Rothwell Peter M , Banning Adrian P , Torgerson David , Gough Moira , Dellagrammaticas Demosthenes , Leigh-Brown Anne , Liapis Christos , Warlow Charles
Published: May 2008

Background

Patients who have severe narrowing at or near the origin of the internal carotid artery as a result of atherosclerosis have a high risk of ischaemic stroke ipsilateral to the arterial lesion. Previous trials have shown that carotid endarterectomy improves long-term outcomes, particularly when performed soon after a prior transient ischaemic attack or mild ischaemic stroke. However, complications may occur during or soon after surgery, the most serious of which is stroke, which can be fatal. It has been suggested that performing the operation under local anaesthesia, rather than general anaesthesia, may be safer. Therefore, a prospective, randomised trial of local versus general anaesthesia for carotid endarterectomy was proposed to determine whether type of anaesthesia influences peri-operative morbidity and mortality, quality of life and longer term outcome in terms of stroke-free survival.

Methods/design

A two-arm, parallel group, multicentre randomised controlled trial with a recruitment target of 5000 patients. For entry into the study, in the opinion of the responsible clinician, the patient requiring an endarterectomy must be suitable for either local or general anaesthesia, and have no clear indication for either type. All patients with symptomatic or asymptomatic internal carotid stenosis for whom open surgery is advised are eligible. There is no upper age limit. Exclusion criteria are: no informed consent; definite preference for local or general anaesthetic by the clinician or patient; patient unlikely to be able to co-operate with awake testing during local anaesthesia; patient requiring simultaneous bilateral carotid endarterectomy; carotid endarterectomy combined with another operation such as coronary bypass surgery; and, the patient has been randomised into the trial previously. Patients are randomised to local or general anaesthesia by the central trial office. The primary outcome is the proportion of patients alive, stroke free (including retinal infarction) and without myocardial infarction 30 days post-surgery. Secondary outcomes include the proportion of patients alive and stroke free at one year; health related quality of life at 30 days; surgical adverse events, re-operation and re-admission rates; the relative cost of the two methods of anaesthesia; length of stay and intensive and high dependency bed occupancy.

Trial registration

Current Controlled Trials ISRCTN00525237
Skin avulsion injury during endotracheal tube extubation – case report of an unusual complication
Authors: Yilmaz Berkhan , Colakoglu Kutay , Gurunluoglu Raffi
Published: May 2008

We report a geriatric case with a full-thickness skin avulsion injury during extubation due to a tube securing tape used to fixate the endotracheal tube. The avulsed skin was sutured back to its original place. Based on this single geriatric patient, we recommend anesthesiologists/anesthetists and surgeons be aware of the potential risk of avulsing the skin with tape during a standard extubation procedure. This may especially occur in geriatric patients who have age related changes as decreased elasticity and resistance to shearing forces that predispose the skin to get traumatized easily.
Significance of Mitochondrial Reactive Oxygen Species in the Generation of Oxidative Stress in Spermatozoa
Authors: Koppers Adam J. , De Iuliis Geoffry N. , Finnie Jane M. , McLaughlin Eileen A. , Aitken R. John
Published: May 2008

Context: Male infertility has been linked with the excessive generation of reactive oxygen species (ROS) by defective spermatozoa. However, the subcellular origins of this activity are unclear.

Objective: The objective of this study was to determine the importance of sperm mitochondria in creating the oxidative stress associated with defective sperm function.

Method: Intracellular measurement of mitochondrial ROS generation and lipid peroxidation was performed using the fluorescent probes MitoSOX red and BODIPY C11 in conjunction with flow cytometry. Effects on sperm movement were measured by computer-assisted sperm analysis.

Results: Disruption of mitochondrial electron transport flow in human spermatozoa resulted in generation of ROS from complex I (rotenone sensitive) or III (myxothiazol, antimycin A sensitive) via mechanisms that were independent of mitochondrial membrane potential. Activation of ROS generation at complex III led to the rapid release of hydrogen peroxide into the extracellular space, but no detectable peroxidative damage. Conversely, the induction of ROS on the matrix side of the inner mitochondrial membrane at complex I resulted in peroxidative damage to the midpiece and a loss of sperm movement that could be prevented by the concomitant presence of α-tocopherol. Defective human spermatozoa spontaneously generated mitochondrial ROS in a manner that was negatively correlated with motility. Simultaneous measurement of general cellular ROS generation with dihydroethidium indicated that 68% of the variability in such measurements could be explained by differences in mitochondrial ROS production.

Conclusion: We conclude that the sperm mitochondria make a significant contribution to the oxidative stress experienced by defective human spermatozoa.
A Novel Adrenocorticotropin Receptor Mutation Alters Its Structure and Function, Causing Familial Glucocorticoid Deficiency
Authors: Artigas Rocío A. , Gonzalez Angel , Riquelme Erick , Carvajal Cristian A. , Cattani Andreína , Martínez-Aguayo Alejandro , Kalergis Alexis M. , Pérez-Acle Tomas , Fardella Carlos E.
Published: May 2008

Context: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by unresponsiveness to ACTH. In this study, two mutations of the ACTH receptor (MC2R) gene are reported in this FGD clinical case.

Objective: The objective of the study was to characterize a novel MC2R gene mutation in a compound heterozygous patient with FGD phenotype.

Design: This was a clinical case description, biochemical, molecular, and bioinformatics analysis to describe a novel MC2R gene mutation.

Patients: The subject of the study was a male diagnosed with primary adrenal insufficiency. The family history showed nonconsanguineous healthy parents, three healthy siblings, and one brother affected with FGD.

Main Outcome Measures: The mutant MC2R-Ala126Ser showed significantly lower activity when it was stimulated with ACTH-(1–24) than did cells transfected with wild-type MC2R.

Results: The molecular studies demonstrated the presence of an adenine heterozygous insertion (InsA1347) in the MC2R gene (G217fs) in the patient. This insertion was due to a frame shift mutation in one allele and a premature stop codon codifying an aberrant receptor of 247 residues (27.2 kDa). We also found a novel heterozygous mutation alanine 126 by serine. Molecular dynamic simulations showed that serine 126 side chain fluctuates forming a noncanonical intrahelical hydrogen bond in the transmembrane helix 3 of the mutated receptor. This produces a structural rearrangement of the MC2R internal cavities that may affect the ligand recognition and signal transduction throughout the G protein.

Conclusions: We propose a molecular explanation for the reduced activity exhibited by the MC2R alanine 126 by serine mutant.
Highly Prevalent Genetic Alterations in Receptor Tyrosine Kinases and Phosphatidylinositol 3-Kinase/Akt and Mitogen-Activated Protein Kinase Pathways in Anaplastic and Follicular Thyroid Cancers
Authors: Liu Zhi , Hou Peng , Ji Meiju , Guan Haixia , Studeman Kimberly , Jensen Kirk , Vasko Vasily , El-Naggar Adel K. , Xing Mingzhao
Published: May 2008

Context: Genetic alterations in receptor tyrosine kinases (RTKs) and phosphatidylinositol 3-kinase (PI3K)/Akt and MAPK pathways have not been fully defined in anaplastic and follicular thyroid cancers [anaplastic thyroid cancer (ATC), follicular thyroid cancer (FTC)].

Objective: The objective of the study was to explore a wide-range genetic basis for the involvement of these pathways in ATC.

Design: We examined mutations and copy number gains of a large panel of genes in these pathways and corresponding phosphorylation of ERK (p-ERK) and Akt.

Results: We found frequent copy gains of RTK genes, including EGFR, PDGFRα and -β, VEGFR1 and 2, KIT, and MET and in PIK3Ca, PIK3Cb, and PDK1 genes in the PI3K/Akt pathway. Mutations of Ras, PIK3Ca, PTEN, and BRAF genes and RET/PTC rearrangements were common, whereas mutations in PDK1, Akt1, Akt2, and RTK genes were uncommon in ATC. Overall, 46 of 48 ATC (95.8%) harbored at least one genetic alteration, and coexistence of two or more was seen in 37 of 48 ATC (77.1%). These genetic alterations were somewhat less common in FTC. Genetic alterations that could activate both the PI3K/Akt and MAPK pathways were found in 39 of 48 ATC (81.3%). RTK gene copy gains were preferentially associated with p-Akt, suggesting their dominant role in activating the PI3K/Akt pathway. The phosphorylation of Akt was far more common than p-ERK in FTC, and both were relatively common and often coexisted in ATC.

Conclusions: Genetic alterations in the RTKs and PI3K/Akt and MAPK pathways are extremely prevalent in ATC and FTC, providing a strong genetic basis for an extensive role of these signaling pathways and the development of therapies targeting these pathways for ATC and FTC, particularly the former.
The 3′-UTR mediates the cellular localization of an mRNA encoding a short plasma membrane protein
Authors: Loya Adi , Pnueli Lilach , Yosefzon Yahav , Wexler Ydo , Ziv-Ukelson Michal , Arava Yoav
Published: May 2008

Cotranslational synthesis of proteins into the endoplasmic reticulum is preceded by targeting of the translating mRNA once a signal peptide emerges from the ribosome exit tunnel. Many mRNAs, however, are unlikely to be targeted by this process because they encode proteins that do not contain a signal peptide or because they are too short to be recognized by the signal recognition particle. Herein we tested the possible involvement of the 3′-UTR in the localization of an mRNA that encodes a very short Saccharomyces cerevisiae protein (Pmp1). We found by ribosome density mapping, sedimentation analysis, differential centrifugation, and fluorescent in situ hybridization that the 3′-UTR is essential for the association of the transcript with membrane compartments. Fusion of the 3′-UTR to heterologous open reading frames conferred on them a sedimentation and cellular localization pattern resembling that of PMP1. Mutation analysis revealed that a repeating UG-rich sequence within the 3′-UTR is important for membrane association. Taken together, our results reveal an essential role for elements within the 3′-UTR in the localization of an mRNA that is likely to be ignored by the standard signal-dependant mechanism.
Clay mineralogy across the P-T boundary of the Xiakou section, China: Evidence of clay provenance and environment
Authors: Hong Hanlie , Zhang Ning , Zhaohui Li , Xue Huijuang , Xia Wenchen , Yu Na
Published: May 2008

The provenance of clays in shaley intervals across the Permian-Triassic boundary (PTB) in the Xiakou section was investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), and the results suggest that the layers have three different provenances. The layer P267-b has a loose texture with an oriented arrangement of detrital clay particles, consisting mainly of illite and minor chlorite with irregular outlines or ragged edges. The dehydroxylation reaction of the clays in this layer is characterized by an intense overlapping endothermic effect at ∼600°C, produced by mixed-layer illite-smectite (I-S) consisting of a mixture of cis-vacant (cv)and trans-vacant (tv) octahedral sheets derived from weathering of detrital illite. Layer P259-b shows a more condensed texture with a dark color, and is composed mainly of I-S and minor illite and chlorite. Evidence for alteration of detrital materials to clay mineral aggregates was observed under SEM. Similar to layer P267-b, an intense dehydroxylation reaction occurs at ∼600°C, indicating clays consisting of a mixture of tv and cv sheets and, therefore, that the sediments were derived from a mixture of terrigenous and volcanic sources, combining the texture and the clay-mineral composition of those sediments. However, the undisturbed lamination and relatively small grain size in this bed indicate a low-energy depositional environment. The clay-mineral compositions of the other layers are mainly of I-S with minor amounts of illite and chlorite. Their endothermic dehydroxylation reaction, however, occurs mainly at ∼660°C, indicating that cv sheets are dominant in the clays, and thus, are derived from smectites of volcanic origin. Observations by SEM show that clay minerals grow at the expense of detrital materials, confirming the diagenetic alteration of volcanic ashes in marine sediments. Illite and chlorite are the detrital clay minerals in the clay layers across the PTB in the Xiakou section. The presence of detrital illite and chlorite in the sediments means that an arid climate prevailed in the region during the end-Permian and early Triassic period.
Natrolitite, an unusual rock — Occurrence and petrographic and geochemical characteristics (Eastern Turkey)
Authors: Çiftçi Emin , Hogan John P. , Kolayli Hasan , Çadirli Emin
Published: May 2008

Very unusual rocks consisting of natrolite (>95 vol.%) ± pargasite (<5 vol.%) and rarealbite (<1 vol. %) have been discovered in the Kop mountain range, eastern Turkey. We propose to call these rocks ‘natrolitite’ and ‘pargasite natrolitite’. They were produced by Na Si metasomatism of dikes and stocks of diorite through replacement of the intermediate primary igneous plagioclase to produce natrolite. The metasomatic alteration produced concentric elliptical zones characterized by distinct mineral assemblages centered on intrusions of diorite. The Central Zone 1 consists of variably albitized diorite with preserved magmatic textures (albite ± andesine ± pargasite ± quartz). Transition Zone 2 comprises natrolite-bearing diorite (natrolite ± albite ± andesine ± pargasite ± calcite ± quartz). Marginal Zone 3 is a rock made up almost entirely of natrolite (natrolite ± pargasite ± albite ± calcite ± chlorite). Outer Zone 4 occurs along the boundary between the natrolitite and the surrounding serpentinite and consists of listvenite, a rock which comprises magnesite, quartz, calcite, mica, talc, and hematite, indicating a role for CO2 in the metasomatic reactions, consistent with the presence of calcite in the alteration zones. Zone 5 consists essentially of brecciated serpentinite with numerous hydrothermal quartz veins and calcite veins. Whole-rock compositions document an increase in Na2O, Al2O3, and H2O from the core (central zone) to themargin while CaO, MgO, and SiO2 decrease. Plagioclase abundance and composition also varies outwards from the central core rocks where it occurs as a primary magmatic phase (∼95 vol.% An41−38) to the alteration zones (<5 vol.% An32−37) due to partial to complete replacement of plagioclase by natrolite with or without rare albite. The natrolites exhibit little variation in Si/Al ratios, ranging between 1.45 and 1.61, and are similar in composition to those reported in the literature. Accompanying pargasitic amphibole also becomes progressively more sodic in composition from the core rocks to the marginal zone rocks. Our analysis indicates that albitization preceded the formation of natrolite and that the formation of natrolite, instead of other more typical alteration minerals (e.g. analcime and paragonite), reflects Na metasomatism at lower chemical potentials for Al2O3 and SiO2. Potential sources of Na could be hypersaline brines or leaching of country rocks, such as trondhjemites. The fluids were driven in hydrothermal convection cells set up by theintrusion of thediorites.
Interaction of aqueous acidic-fluoride waste with natural tunisian soil
Authors: Hamdi Noureddine , Srasra Ezzedine
Published: May 2008

Clayey soils are essential materials used to reduce hydraulic conductivity and pollutant migration, common at sites of waste disposal. This study investigates the possible use of a Tunisian soil as a lining material for disposal sites for acidic-fluoride wastes. A permeability test on a waste-solution sample (pH = 2.7) obtained from a disposal site in southern Tunisia was conducted over a period of about 2 years. The test results show that the permeability decreased with time until stabilized at 8.33 × 10−11 m/s. After the permeability test, the samples retrieved from the permeameter show a degradation state which varied with the thickness of the specimen. These samples can be classified into three zones (Z1: unaffected, Z2: moderately affected; and Z3: extensively affected). Physicochemical characterization of the three samples (Z1, Z2, and Z3), and of the original argillaceous soil, was by X-ray diffraction, Fourier transform infrared spectroscopy, differential thermal and thermal gravimetric analysis, 29Si and 27Al nuclear magnetic resonance, and N2-adsorption techniques. The original sample consists essentially of palygorskite, kaolinite, and quartz. Sample Z3 underwent complete dissolution of kaolinite which supports the precipitation of fluoroaluminate and the appearance of an X-ray amorphous silica phase. In samples Z1 and Z2, the soil adsorbs fluoride at a rate of ∼68.5 mg/g and is highly resistant to acidic attack.
Quantitative phase analysis of bentonites by the rietveld method
Authors: Ufer K. , Stanjek H. , Roth G. , Dohrmann R. , Kleeberg R. , Kaufhold S.
Published: May 2008

Thirty six bentonite samples from 16 different locations were examined in order to demonstrate the applicability of a new Rietveld description approach for quantitative phase analysis. X-ray diffraction patterns of the bulk material were obtained and analyzed by the Rietveld method. The samples contain up to ten different minerals, with dioctahedral smectite as the major component. A model for turbostratic disorder of smectites was formulated inside a structure-description file of the Rietveld program BGMN. The quality of the refinements was checked using an internal standard mineral (10.0 or 20.0 wt.% corundum) and by cross-checking results with X-ray fluorescence (XRF) data. The corundum content was reproduced with only small deviations from the nominal values. A comparison of the chemical composition obtained by XRF and the composition as re-calculated from quantitative Rietveld results shows a satisfactory agreement, although X-ray amorphous components such as volcanic glasses were not considered. As a result of this study, the Rietveld method combined with the new structure model for turbostratic disorder has proven to be a suitable method for routine quantitative analysis of bentonites with smectites as the dominant clay minerals.
Ruled Weingarten hypersurfaces in
Authors: Asperti Antonio C. , Valério Barbara C.
Published: May 2008

In this paper we classify the connected ruled Weingarten hypersurfaces in .
A Gauss–Bonnet formula for closed semi-algebraic sets
Authors: Dutertre Nicolas
Published: May 2008

We prove a Gauss–Bonnet formula for closed semi-algebraic sets.
Inner ideals and intrinsic subspaces of linear pair geometries
Authors: Bertram Wolfgang , Löwe Harald
Published: May 2008

We introduce the notion of intrinsic subspaces of linear and affine pair geometries, which generalizes the one of projective subspaces of projective spaces. We prove that, when the affine pair geometry is the projective geometry of a Lie algebra introduced in [W. Bertram, K.-H. Neeb, Projective completions of Jordan pairs. I. The generalized projective geometry of a Lie algebra. J. Algebra
277 (2004), 474–519. MR2067615 (2005f:17031) Zbl 02105235], such intrinsic subspaces correspond to inner ideals in the associated Jordan pair, and we investigate the case of intrinsic subspaces defined by the Peirce-decomposition which is related to 5-gradings of the projective Lie algebra. These examples, as well as the examples of general and Lagrangian flag geometries, lead to the conjecture that geometries of intrinsic subspaces tend to be themselves linear pair geometries.
On the relative lengths of the sides of convex polygons
Authors: Su Zhanjun , Ding Ren
Published: May 2008

Doliwka and Lassak proved that if n ≤ 5 then every convex n-gon has a relatively short side and a relatively long side. In this paper we prove that this is true for n ≤ 5 only. More precisely, for any n ≥ 6, there exist n-gons without any relatively short sides.
The structure of full polarized embeddings of symplectic and Hermitian dual polar spaces
Authors: Cardinali Ilaria , De Bruyn Bart
Published: May 2008

Let Δ be a thick dual polar space of rank n ≥ 2 and let e be a full polarized embedding of Δ into a projective space ∑. For every point x of Δ and every i ∈ {0, …, n}, let T
i
(x) denote the subspace of ∑ generated by all points e(y) with d(x, y) ≤ i. We show that T
i
(x) does not contain points e(z) with d(x, z) ≥ i + 1. We also show that there exists a well-defined map ei
x
from the set of (i – 1)-dimensional subspaces of the residue Res Δ(x) of Δ at the point x (which is a projective space of dimension n – 1) to the set of points of the quotient space T
i
(x)/T
i –1 (x). In this paper we study the structure of the maps ei
x
and the subspaces Ti(x) for some particular full polarized embeddings of the symplectic and the Hermitian dual polar spaces. Our investigations allow us to answer some questions asked in the literature.
A Kantor family admitting a normal F-factor constitutes a p-group
Authors: Thas Koen
Published: May 2008

We solve a more general version of a conjecture of D. Hachenberger [D. Hachenberger, Groups admitting a Kantor family and a factorized normal subgroup. Des. Codes Cryptogr.
8 (1996), 135–143. MR1393979 (98c:20042) Zbl 0877.51007] by showing that a group admitting a Kantor family with a thick F-factor is a p-group for some prime p.
An improvement of a theorem of Van de Ven
Authors: Repetto Flavia
Published: May 2008

In this paper we improve a classical result of Van de Ven which characterizes linear subspaces of as the only smooth closed subvarieties of for which the normal sequence splits (see [A. Van de Ven, A property of algebraic varieties in complex projective spaces. In: Colloque
Géom. Diff. Globale (Bruxelles, 1958), 151–152, Centre Belge Rech. Math., Louvain 1959. MR0116361 (22 #7149) Zbl 0092.14004]). Precisely we prove the following: Let X be a submanifold of of dimension ≥ 3, and Y ⊆ X a submanifold of X of dimension ≥ 2. Assume that Span(Y) = Span(X), where Span(X) is the smallest linear subspace of containing X. Then the exact sequence: splits if and only if X is a linear subspace of .
Ample vector bundles with zero loci of small Δ-genera
Authors: Lanteri Antonio , Novelli Carla
Published: May 2008

Let X be a smooth complex projective variety endowed with an ample vector bundle ε admitting a global section whose zero locus is a smooth subvariety Z of the expected dimension, and let H be an ample line bundle on X, whose restriction HZ
to Z is very ample. Triplets (X, ε, H) are studied and classified under the assumption that the delta genus of (Z, HZ
) is either small (≤ 3) or small in comparison with the corank of ε or the degree.
Location of radial centres of convex bodies
Authors: Herburt Irmina
Published: May 2008

The radial centre of a convex body A in ℝ
n
is the point in A at which the mean value of distances from the boundary of A, with respect to all directions, attains its maximum. We prove that if A is smooth, then its radial centre is an interior point of A.
Species composition and seasonal changes in macroalgal blooms in lagoons along the southeastern Gulf of California
Authors: Piñón-Gimate Alejandra , Serviere-Zaragoza Elisa , Ochoa-Izaguirre María Julia , Páez-Osuna Federico
Published: May 2008

Species composition and seasonal changes in macroalgal blooms in six coastal lagoons highly impacted by human activities were tracked for the three seasons between May 2004 and April 2005. Though temperatures were lower during the cold season than during the dry and rainy seasons and some locations showed variations in salinity during the rainy season, nutrient concentrations showed no defined pattern and varied according to season and location. A total of 10 seaweed species and the cyanobacterium Microcoleus lyngbyaceus had biomasses >1 g m-2 dry weight, but only four species represented >1% of the annual biomass. During the dry season, Spyridia filamentosa had the highest biomass (57.5 g m-2). During the rainy season, Gracilaria vermiculophylla was the most conspicuous and abundant species (64.0–291.0 g m-2) and during the cold season, Caulerpa sertularioides had the highest biomass (180.1 g m-2). Abundances of these species were higher than previously reported for this region. Correlation analyses showed a positive correlation between total phosphorus and the biomass of G. vermiculophylla, suggesting that this nutrient might be limiting its growth. C. sertularioides abundance had a positive correlation with N:P ratios, suggesting that high concentrations of nitrogen relative to low phosphorus levels favor its growth. These analyses revealed that nutrient concentrations are most likely to affect macroalgal growth, but temperature and salinity also play a role. This information may be useful for monitoring future blooms and determining changes over time.
Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico
Authors: Martin Summer R. , Onuf Christopher P. , Dunton Kenneth H.
Published: May 2008

We used aerial photography and GIS to establish a quantitative baseline of propeller and off-road vehicle (ORV) scarring in seagrass and wind-tidal flats of the upper Laguna Madre in the Padre Island National Seashore (Texas, USA). We also examined scar recovery through comparison of recent (2002, 2005) and historical (1967) aerial photographs of the study area. Scarring intensity was calculated using two different methods. In the first, polygons were visually drawn around groups of scars on digital images. Scarring intensity was estimated as light (<5%), moderate (5–20%), or severe (>20%), based on the total coverage of scars within each polygon (taking into account the length, width, and density of scars). We developed a more objective method that employed creation of vector grid cells and buffers that incorporated the localized ecological impact of scars. Results of spatial and temporal analysis revealed that the polygon approach greatly underestimated the magnitude of scarring. For example, in a single photograph, 7% of seagrass area was lightly scarred according to the polygon method; but light scarring increased to 51% according to grid analysis of the same image. Our results also indicated that propeller scars in Halodule wrightii beds appear to recover in less than three years and ORV tracks have persisted in the wind-tidal flats for at least 38 years. Our approach provides resource managers with procedures for a more objective and efficient assessment of physical disturbances to seagrass and wind-tidal flats caused by boats and ORVs.
Seasonal variation in a deep subtidal Zostera marina L. bed in southern Spain (western Mediterranean Sea)
Authors: Rueda Jose L. , Salas Carmen , Marina Pablo
Published: May 2008

The seasonal variation in biometric and biomass features of a deep subtidal Zostera marina bed (depth 12–14 m) in Cañuelo Bay (southern Spain) was studied through an annual cycle. Shoot density was greatest in September 2004 (402.4±22.01 shoots m-2) and lowest in March 2005 (220.8±51.2 shoots m-2). Shoots with inflorescences were only observed in June 2004, with up to 9.6 fertile shoots m-2. Mean shoot height, leaf width and leaf area index also varied seasonally, with maximum values in June–September and minimum values in December– March. The above-ground (leaf) biomass also varied seasonally, with maximum values in June–September (90–100 g dw m-2) and minimum values in March 2005 (8.4±2.7 g dw m-2). The below-ground (rhizome) biomass remained very stable (90–100 g dw m-2) throughout the year. The deep Z. marina bed in Cañuelo Bay had a similar, but less pronounced, seasonal pattern compared to that observed in shallower beds in temperate areas of the Northern Hemisphere. The rather low attenuation coefficient and stable temperature (14–21°C) of the water column throughout the year may favour the development of eelgrass beds at this depth and in this part of the distribution range.
Short-term indicators of seagrass transplant stress in response to sediment bacterial community disruption
Authors: Milbrandt Eric C. , Greenawalt-Boswell Jaime , Sokoloff Paul D.
Published: May 2008

Bacterial communities in sediments engage in activities that determine the pathways and rates of organic matter remineralization. Changes in bacterial community composition might result in greater restoration success if interactions among seagrasses, sediment, and bacterial communities were elucidated. A manipulative experiment that disrupted the sediment bacterial community examined the response of Thalassia testudinum transplants. Planting units were transported to a suitable location and replanted with either autoclaved, transplant, or donor site sediments. Sediments from the rhizosphere were sub-sampled for analysis of the 16S rDNA gene. The autoclave treatment group had significantly lower bacterial diversity than the other treatments, as measured with terminal restriction fragment length polymorphism. Significantly higher mortality of the transplants was observed in the autoclave treatment group, while mortality in the donor and transplant treatment groups was low relative to the control group. Rhizosphere disruption through the removal of surrounding sediments did not increase mortality, while manipulating the composition of the bacterial community increased mortality in transplants. A native bacterial community was a critical component for minimizing short-term stress associated with a seagrass transplant, which suggests a tighter coupling between seagrasses and sediment bacterial communities than previously thought.
Chylocladia wynnei sp. nov. (Champiaceae, Rhodophyta) from the Mediterranean Sea
Authors: Alongi Giuseppina , Cormaci Mario , Furnari Giovanni
Published: May 2008

A new species, Chylocladia wynnei sp. nov., is described from the Mediterranean Sea. It consists of 2–4 terete, unbranched erect axes, 5–10(–13) mm high, arising from a discoid holdfast. Axes, covered by a thick mucilaginous layer, are hollow throughout. They are divided into segments by monostromatic diaphragms and are constricted at the diaphragms. Axes have a unilayered cortex and longitudinal filaments lining their inner surface; gland cells are cut off from these filaments. Gametophytic plants are dioecious and consist of only two segments. Male thalli have spermatangia in superficial sori located between the two segments. One or two spherical sessile cystocarps are borne on the distal part of the basal segment. Tetrasporic plants comprise 4–5 segments; tetrahedrally divided tetrasporangia are scattered throughout the thallus. These sporangia are transformed from larger cortical cells and, when mature, they protrude into the thallus cavity. Diminutive stature and unbranched erect axes covered with a thick mucilaginous layer clearly distinguish C. wynnei from previously described species of Chylocladia.
Manuscript Digitization at the Hill Museum & Manuscript Library: Building on the Legacy of Microfilm
Authors: Torborg Wayne
Published: May 2008

In the mid-1960's a group of Benedictine monks at Saint John's Abbey and University in central Minnesota faced a challenge. They were wondering what could be done to preserve the precious hand-written religious books located in European monasteries and libraries. The devastation of World War II was a recent memory, and the potential loss of cultural material in the event of the Cold War suddenly turning “hot” was difficult to imagine. The monks had two goals: the preservation of the manuscript's contents and the creation of a means for scholars to easily access them. The task was daunting – thousands of manuscripts existed in dozens of Western European locations.
The Mildred Wirt Benson Digital Collection: Digitizing the Mysterious Nancy Drew Author
Authors: Wolfe Jen
Published: May 2008

The University of Iowa, first in the nation to offer advanced degrees for creative writing and home of the famed Iowa Writer's Workshop, has a long history of turning out many of America's best-known authors. However, one of the most popular and enduring novelists ever to have graduated from the UI is hardly a household name. Mildred Wirt Benson, under the much more familiar pseudonym Carolyn Keene, wrote the first 23 Nancy Drew mystery novels. The longest-running juvenile fiction series ever, the series has sold over 200 million books, received translation into 25 languages, and inspired adaptation for numerous film and television versions. In 2007, staff of the UI's Digital Library Services department embarked on a digitization project (
Rational Optimization and ImagingIn Vivoof a Genetically Encoded Optical Voltage Reporter
Authors: Sjulson Lucas , Miesenböck Gero
Published: May 2008

The hybrid voltage sensor (hVOS) combines membrane-targeted green fluorescent protein and the hydrophobic anion dipicrylamine (DPA) to provide a promising tool for optical recording of electrical activity from genetically defined populations of neurons. However, large fluorescence signals are obtained only at high DPA concentrations (>3 μm) that increase membrane capacitance to a level that suppresses neural activity. Here, we develop a quantitative model of the sensor to guide its optimization and achieved an approximate threefold increase in fractional fluorescence change at a lower DPA concentration of 2 μm. Using this optimized voltage reporter, we perform optical recordings of evoked activity in theDrosophilaantennal lobe with millisecond temporal resolution but fail to detect action potentials, presumably because spike initiation and/or propagation are inhibited by the capacitive load added even at reduced DPA membrane densities. We evaluate strategies for potential further improvement of hVOS quantitatively and derive theoretical performance limits for optical voltage reporters in general.
Aquaporin-4-Deficient Mice Have Increased Extracellular Space without Tortuosity Change
Authors: Yao Xiaoming , Hrabětová Sabina , Nicholson Charles , Manley Geoffrey T.
Published: May 2008

Aquaporin-4 (AQP4) is the major water channel expressed at fluid–tissue barriers throughout the brain and plays a crucial role in cerebral water balance. To assess whether these channels influence brain extracellular space (ECS) under resting physiological conditions, we used the established real-time iontophoresis method with tetramethylammonium (TMA+) to measure three diffusion parameters: ECS volume fraction (α), tortuosity (λ), and TMA+loss (k′).In vivomeasurements were performed in the somatosensory cortex of AQP4-deficient (AQP4−/−) mice and wild-type controls with matched age. Mice lacking AQP4 showed a 28% increase in α (0.23 ± 0.007 vs 0.18 ± 0.003) with no differences in λ (1.62 ± 0.04 vs 1.61 ± 0.02) andk′(0.0045 ± 0.0001 vs 0.0031 ± 0.0009 s−1). Additional recordings in brain slices showed similarly elevated α in AQP4−/−mice, and no differences in λ andk′between the two genotypes. This is the first direct comparison of ECS properties in adult mice lacking AQP4 water channels with wild-type animals and demonstrates a significant enlargement of the volume fraction but no difference in hindrance to TMA+diffusion, expressed as tortuosity. These findings provide direct evidence for involvement of AQP4 in modulation of the ECS volume fraction and provide a basis for future modeling of water and ion transport in the CNS.
Action-Based Body Maps in the Spinal Cord Emerge from a Transitory Floating Organization
Authors: Granmo Marcus , Petersson Per , Schouenborg Jens
Published: May 2008

During development primary afferents grow into and establish neuronal connections in the spinal cord, thereby forming the basis for how we perceive sensory information and control our movements. In the somatosensory system, myriads of primary afferents, conveying information from different body locations and sensory modalities, get organized in the dorsal horn of the spinal cord so that spinal multisensory circuits receive topographically ordered information. How this intricate pathfinding is brought about during development is, however, largely unknown. Here we show that a body representation closely related to motor patterns emerges from a transitory floating and plastic organization through profound activity-dependent rewiring, involving both sprouting and elimination of afferent connections, and provide evidence for cross-modality interactions in the alignment of the multisensory input. Thus, far from being inborn and stereotypic, the dorsal horn of the spinal cord now appears to be a highly adaptive brain–body interface.