bluuebunny/crossref_metadata_2025 huggingface dataset:
Multispecies diffusion models: A study of uranyl species diffusion
Authors: Liu Chongxuan , Shang Jianying , Zachara John M.
Published: October 2011

Rigorous numerical description of multispecies diffusion requires coupling of species, charge, and aqueous and surface complexation reactions that collectively affect diffusive fluxes. The applicability of a fully coupled diffusion model is, however, often constrained by the availability of species self‐diffusion coefficients, as well as by computational complication in imposing charge conservation. In this study, several diffusion models with variable complexity in charge and species coupling were formulated and compared to describe reactive multispecies diffusion in groundwater. Diffusion of uranyl [U(VI)] species was used as an example in demonstrating the effectiveness of the models in describing multispecies diffusion. Numerical simulations found that a diffusion model with a single, common diffusion coefficient for all species was sufficient to describe multispecies U(VI) diffusion under a steady state condition of major chemical composition, but not under transient chemical conditions. Simulations revealed that for multispecies U(VI) diffusion under transient chemical conditions, a fully coupled diffusion model could be well approximated by a component‐based diffusion model when the diffusion coefficient for each chemical component was properly selected. The component‐based diffusion model considers the difference in diffusion coefficients between chemical components, but not between the species within each chemical component. This treatment significantly enhanced computational efficiency at the expense of minor charge conservation. The charge balance in the component‐based diffusion model can be enforced, if necessary, by adding a secondary migration term resulting from model simplification. The effect of ion activity coefficient gradients on multispecies diffusion is also discussed. The diffusion models were applied to describe U(VI) diffusive mass transfer in intragranular domains in two sediments collected from U.S. Department of Energy's Hanford 300A, where intragranular diffusion is a rate‐limiting process controlling U(VI) adsorption and desorption. The grain‐scale reactive diffusion model was able to describe U(VI) adsorption/desorption kinetics that had been previously described using a semiempirical, multirate model. Compared with the multirate model, the diffusion models have the advantage to provide spatiotemporal speciation evolution within the diffusion domains.
Columnar Specificity of Microvascular Oxygenation and Blood Flow Response in Primary Visual Cortex: Evaluation by Local Field Potential and Spiking Activity
Authors: Wang Zheng , Roe Anna W
Published: October 2011

The relation of cortical microcirculation, oxygen metabolism, and underlying neuronal network activity remains poorly understood. Anatomical distribution of cortical microvasculature and its relationship to cortical functional domains suggests that functional organizations may be revealed by mapping cerebral blood flow responses. However, there is little direct experimental evidence and a lack of electrophysiological evaluation. In this study, we mapped ocular-dominance columns in primary visual cortex (V1) of anesthetized macaques with capillary flow-based laser speckle contrast imaging and deoxyhemoglobin-based intrinsic optical imaging. In parallel, the local field potentials (LFPs) and spikes were recorded from a linear array of eight microelectrodes, carefully positioned into left and right eye columns in V1. We found differential activation maps of blood flow, after masking large superficial draining vessels, exhibited a column-like pattern similar as the oximetric maps. Both the activated spikes and γ-band LFP demonstrated corresponding eye preference, consistent with the imaging maps. Our results present direct support in favor of previous proposals that the regulation of microcirculation can be as fine as the submillimeter scale, suggesting that cortical vasculature is functionally organized at the columnar level in a manner appropriate for supplying energy demands of functionally specific neuronal populations.
Leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation is associated with cell-type-dependent splicing of mtAspRS mRNA
Authors: van Berge Laura , Dooves Stephanie , van Berkel Carola G.M. , Polder Emiel , van der Knaap Marjo S. , Scheper Gert C.
Published: October 2011

LBSL (leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation) is an autosomal recessive white matter disorder with slowly progressive cerebellar ataxia, spasticity and dorsal column dysfunction. Magnetic resonance imaging shows characteristic abnormalities in the cerebral white matter and specific brain stem and spinal cord tracts. LBSL is caused by mutations in the gene DARS2, which encodes mtAspRS (mitochondrial aspartyl-tRNA synthetase). The selective involvement of specific white matter tracts in LBSL is striking since this protein is ubiquitously expressed. Almost all LBSL patients have one mutation in intron 2 of DARS2, affecting the splicing of the third exon. Using a splicing reporter construct, we find cell-type-specific differences in the sensitivity to these mutations: the mutations have a larger effect on exon 3 exclusion in neural cell lines, especially neuronal cell lines, than in non-neural cell lines. Furthermore, correct inclusion of exon 3 in the normal mtAspRS mRNA occurs less efficiently in neural cells than in other cell types, and this effect is again most pronounced in neuronal cells. The combined result of these two effects may explain the selective vulnerability of specific white matter tracts in LBSL patients.
LL37 and hBD-3 elevate the β-1,3-exoglucanase activity of Candida albicans Xog1p, resulting in reduced fungal adhesion to plastic
Authors: Chang Hao-Teng , Tsai Pei-Wen , Huang Hsin-Hui , Liu Yu-Shu , Chien Tzu-Shan , Lan Chung-Yu
Published: October 2011

The opportunistic fungus Candida albicans causes oral thrush and vaginal candidiasis, as well as candidaemia in immunocompromised patients including those undergoing cancer chemotherapy, organ transplant and those with AIDS. We previously found that the AMPs (antimicrobial peptides) LL37 and hBD-3 (human β-defensin-3) inhibited C. albicans viability and its adhesion to plastic. For the present study, the mechanism by which LL37 and hBD-3 reduced C. albicans adhesion was investigated. After AMP treatment, C. albicans adhesion to plastic was reduced by up to ~60% and was dose-dependent. Our previous study indicated that LL37 might interact with the cell-wall β-1,3-exoglucanase Xog1p, which is involved in cell-wall β-glucan metabolism, and consequently the binding of LL37 or hBD-3 to Xog1p might cause the decrease in adhesion. For the present study, Xog1p(41–438)-6H, an N-terminally truncated, active, recombinant construct of Xog1p and Xog1p fragments were produced and used in pull-down assays and ELISA in vitro, which demonstrated that all constructs interacted with both AMPs. Enzymatic analyses showed that LL37 and hBD-3 enhanced the β-1,3-exoglucanase activity of Xog1p(41–438)-6H approximately 2-fold. Therefore elevated Xog1p activity might compromise cell-wall integrity and decrease C. albicans adhesion. To test this hypothesis, C. albicans was treated with 1.3 μM Xog1p(41–438)-6H and C. albicans adhesion to plastic decreased 47.7%. Taken together, the evidence suggests that Xog1p is one of the LL37/hBD-3 targets, and elevated β-1,3-exoglucanase activity reduces C. albicans adhesion to plastic.
Use of Orthodontic Mini-Implants for Maxillomandibular Fixation in Mandibular Fracture
Authors: Pires Mario Sergio Medeiros , Reinhardt Leandro Calcagno , de Marco Antonello Guilherme , Torres do Couto Ricardo
Published: October 2011

Orthodontic appliances for skeletal anchorage are becoming increasingly more common in clinical practice. Similarly, different terms such as mini-implants, microimplants, and miniscrews have been used. There is a wide array of appliances currently on the market, in different designs and sizes, diameters, degree of titanium purity, and surface treatment. These appliances have been used for a variety of indications, including tooth retraction, intrusion, and traction. This study aimed to report the clinical case of a 19-year-old patient with a fractured mandible and to propose a novel use of mini-implants: the perioperative placement of mini-implants as anchors for maxillomandibular fixation steel wire ligatures. We concluded that this appliance provides an effective maxillomandibular fixation in patients with mandibular fracture, with little increase in the cost of surgery.
No Masking between Test and Mask Components in Perceptually Different Depth Planes
Authors: Hibbeler Patrick J , Olzak Lynn A
Published: October 2011

2-D cues to perceived depth organization have been used to segregate test and mask stimulus components in a discrimination task. Observers made either spatial-frequency or orientation judgments on a rectangular test component by itself or in the presence of constant rectangular masks. There were two basic masking conditions: same-plane or different-plane. In the same-plane conditions, the test components and masks are perceived as existing in the same depth plane. In the different-plane conditions, the test and mask components are perceived to exist in different depth planes. The perception of different depth planes was achieved by using perceived occlusion, which could place either component closer or further from the observer. The results suggest that when test and mask components are separated into different depth planes they no longer influence one another. This effect could be observed in either depth organization, test components in front of the masks or mask components in front of the test. These results indicate that the figure – ground organization of components is not important. Only the designation as existing in the same or different depth planes affects whether or not a mask is effective.
Koffka's Effect is Mediated by Figure Thickness at the Joining Region
Authors: Huang Abigail E , Hon Alice J , Li Xintong , McCormick Meghan C , Patel Dina A , Chubb Charles , Altschuler Eric L
Published: October 2011

Three-quarters of a century ago Gestalt psychologist Kurt Koffka described a remarkable effect: when a contiguous gray ring is placed on a background half one shade of gray, half another, the ring appears homogeneous. However, if the ring is divided, the two halves of the ring appear different shades of gray, the half of the ring on the darker background appearing lighter than the half of the ring on the lighter background. The Gestalt principle of continuity is used to explain this effect. But what microscopic principles might be mediating this effect? Recently we found sufficiently thin rings (annuli) appear heterogeneous even when geometrically continuous. Here, using crescent-shaped figures instead of the circular annuli used for the traditional Koffka effect, we show that this effect of thickness of the ring is mediated by the thickness at the boundary of the region where the halves of the figure are joined.
Perception in the Absence of Attention: Perceptual Processing in the Roelofs Effect during Inattentional Blindness
Authors: Lathrop William B , Bridgeman Bruce , Tseng Philip
Published: October 2011

We present two experiments that examine sensory processing during conditions of inattentional blindness. A large rectangular frame that normally induces a Roelofs effect can go unreported due to inattentional blindness. Even when participants fail to report the frame, they mislocalize an attended target in a way consistent with having processed the frame. A more demanding visuospatial distractor task can increase inattentional blindness during conditions of divided attention, but has no effect on the spatial mislocalization illusion. Our results support theories that postulate a significant amount of perceptual processing in the absence of attention.
Drawing with Divergent Perspective, Ancient and Modern
Authors: Howard Ian P , Allison Robert S
Published: October 2011

Before methods for drawing accurately in perspective were developed in the 15th century, many artists drew with divergent perspective. But we found that many university students draw with divergent perspective rather than with the correct convergent perspective. These experiments were designed to reveal why people tend to draw with divergent perspective. University students drew a cube and isolated edges and surfaces of a cube. Their drawings were very inaccurate. About half the students drew with divergent perspective like artists before the 15th century. Students selected a cube from a set of tapered boxes with great accuracy and were reasonably accurate in selecting the correct drawing of a cube from a set of tapered drawings. Each subject's drawing was much worse than the drawing selected as accurate. An analysis of errors in drawings of a cube and of isolated edges and surfaces of a cube revealed several factors that predispose people to draw in divergent perspective. The way these factors intrude depends on the order in which the edges of the cube are drawn.
Seeing with Sound? Exploring Different Characteristics of a Visual-to-Auditory Sensory Substitution Device
Authors: Brown David , Macpherson Tom , Ward Jamie
Published: October 2011

Sensory substitution devices convert live visual images into auditory signals, for example with a web camera (to record the images), a computer (to perform the conversion) and headphones (to listen to the sounds). In a series of three experiments, the performance of one such device (‘The vOICe’) was assessed under various conditions on blindfolded sighted participants. The main task that we used involved identifying and locating objects placed on a table by holding a webcam (like a flashlight) or wearing it on the head (like a miner's light). Identifying objects on a table was easier with a hand-held device, but locating the objects was easier with a head-mounted device. Brightness converted into loudness was less effective than the reverse contrast (dark being loud), suggesting that performance under these conditions (natural indoor lighting, novice users) is related more to the properties of the auditory signal (ie the amount of noise in it) than the cross-modal association between loudness and brightness. Individual differences in musical memory (detecting pitch changes in two sequences of notes) was related to the time taken to identify or recognise objects, but individual differences in self-reported vividness of visual imagery did not reliably predict performance across the experiments. In general, the results suggest that the auditory characteristics of the device may be more important for initial learning than visual associations.
The Role of Spatial Organization in Preference for Color Pairs
Authors: Schloss Karen B , Palmer Stephen E
Published: October 2011

We investigated how spatial organization influences color-pair preference asymmetries: differential preference for one color pair over another when the pairs contain the same colors in opposite spatial configurations. Schloss and Palmer (2011, Attention, Perception, & Psychophysics73 551 – 571) found weak figure – ground preference asymmetries for small squares centered on large squares in aesthetic ratings. Here, we found robust preference asymmetries using a more sensitive forced-choice task: participants strongly prefer pairs with yellower, lighter figures on bluer, darker grounds (experiment 1). We also investigated which spatial factors influence these preference asymmetries. Relative area of the two component regions is clearly important, and perceived 3-D area of the 2-D displays (ie after the ground is amodally completed behind the figure) is more influential than 2-D area (experiment 2). Surroundedness is not required, because yellowness – blueness effects were comparable for pairs in which the figure was surrounded by the ground, and for mosaic arrangements in which the regions were adjacent and separated by a gap (experiment 3). Lightness – darkness effects, however, were opposite for figure – ground versus mosaic organizations: people prefer figure – ground organizations in which smaller regions are lighter, but prefer mosaic organizations in which smaller regions are darker. Physiological, phenomenological, and ecological explanations of the reported results are discussed.
Configural Information is Processed Differently in Human Action
Authors: Loucks Jeff
Published: October 2011

Recent evidence indicates that observers' sensitivity to configural information in dynamic human action is disrupted when action is inverted, whereas sensitivity to featural action information is not. The current research involved two experiments that expand upon this basic finding. Experiment 1 revealed that featural and configural action information are processed similarly in static representations of action as in dynamic action. Experiment 2 indicated that configural processing is uniquely sensitive to orientation only in human action as compared to a similar control stimulus. These findings further support the idea that the perception of action recruits specialized orientation-specific configural processing, and parallel similar findings in face perception and visual expertise.
A new type of water pollution: concrete drainage infrastructure and geochemical contamination of urban waters
Authors: Wright I. A. , Davies P. J. , Findlay S. J. , Jonasson O. J.
Published: October 2011

Stormwater and other urban runoff is often conveyed by concrete infrastructure and it is plausible that the chemistry of urban streams is modified by the leaching of minerals from this infrastructure. We tested this hypothesis by analysing major anions, cations and other chemical variables from urban and reference freshwater streams in northern Sydney. Urban streams tended towards neutral pH whereas non-urban reference streams were acidic. Bicarbonate levels were more than 10 times higher and calcium concentrations were more than six times higher in urban streams than reference streams. Experimental analysis revealed that the chemistry of rainwater changed when passed through concrete pipes and down concrete gutters, suggesting dissolution of cement products from various concrete materials used for urban drainage. This study concluded that the use of concrete – particularly its application for urban drainage – is responsible for some of the modifications to urban stream geochemistry. Thus, urban geology should be considered as an important factor that contributes to the urban stream syndrome.
A cardiac pathway of cyclic GMP-independent signaling of guanylyl cyclase A, the receptor for atrial natriuretic peptide
Authors: Klaiber Michael , Dankworth Beatrice , Kruse Martin , Hartmann Michael , Nikolaev Viacheslav O. , Yang Ruey-Bing , Völker Katharina , Gaßner Birgit , Oberwinkler Heike , Feil Robert , Freichel Marc , Groschner Klaus , Skryabin Boris V. , Frantz Stefan , Birnbaumer Lutz , Pongs Olaf , Kuhn Michaela
Published: October 2011

Cardiac atrial natriuretic peptide (ANP) regulates arterial blood pressure, moderates cardiomyocyte growth, and stimulates angiogenesis and metabolism. ANP binds to the transmembrane guanylyl cyclase (GC) receptor, GC-A, to exert its diverse functions. This process involves a cGMP-dependent signaling pathway preventing pathological [Ca
2+
]
i
increases in myocytes. In chronic cardiac hypertrophy, however, ANP levels are markedly increased and GC-A/cGMP responses to ANP are blunted due to receptor desensitization. Here we show that, in this situation, ANP binding to GC-A stimulates a unique cGMP-independent signaling pathway in cardiac myocytes, resulting in pathologically elevated intracellular Ca
2+
levels. This pathway involves the activation of Ca
2+
‐permeable transient receptor potential canonical 3/6 (TRPC3/C6) cation channels by GC-A, which forms a stable complex with TRPC3/C6 channels. Our results indicate that the resulting cation influx activates voltage-dependent L-type Ca
2+
channels and ultimately increases myocyte Ca
2
+
i
levels. These observations reveal a dual role of the ANP/GC-A–signaling pathway in the regulation of cardiac myocyte Ca
2+
i
homeostasis. Under physiological conditions, activation of a cGMP-dependent pathway moderates the Ca
2+
i
-enhancing action of hypertrophic factors such as angiotensin II. By contrast, a cGMP-independent pathway predominates under pathophysiological conditions when GC-A is desensitized by high ANP levels. The concomitant rise in [Ca
2+
]
i
might increase the propensity to cardiac hypertrophy and arrhythmias.
Efficient ultraviolet-blue to near-infrared downconversion in Bi–Dy–Yb-doped zeolites
Authors: Bai Zhenhua , Fujii Minoru , Hasegawa Takashi , Imakita Kenji , Mizuhata Minoru , Hayashi Shinji
Published: October 2011

Ultraviolet-blue to near-infrared (NIR) downconversion is investigated for the Dy3+–Yb3+ couple in zeolites by steady-state and time-resolved photoluminescence (PL) spectra, and PL excitation spectra. Upon excitation of the 4F9/2 level of Dy3+, NIR quantum cutting could occur through a two-step energy transfer from one Dy3+ ion to two neighbouring Yb3+ ions via an intermediate level. The energy transfer efficiency from the 4F9/2 level is estimated to be 42%, and the intrinsic PL quantum efficiency of Yb3+ emission reaches 54%. The findings may have potential application in enhancing the energy efficiency of silicon-based solar cells.
Thermal roughening transition of a dissolved nickel surface
Authors: Saitou M
Published: October 2011

A thermal roughening transition in a polycrystalline nickel surface dissolved anodically by a rectangular pulse current is found. The drastic change in normalized dissolution mass at the transition temperature is shown to be consistent with that in surface roughness such as a smooth or rough surface. The normalized dissolution mass below the transition temperature exponentially decreases with the frequency of the rectangular pulse current and asymptotically approaches a fixed value much less than 1.0. The normalized dissolution mass above the transition temperature is almost equal to 1.0 irrespective of the frequency. The frequency dependence of the normalized dissolution mass is described by an electric circuit model equivalent to an electric double layer.
Anomalous octahedral distortions in LaFe1−xNixO3
Authors: Idrees M , Nadeem M , Shah Matiullah , Shin T J
Published: October 2011

Perovskite-type LaFe1−x
Ni
x
O3 in the composition range with orthorhombic crystal structure (x = 0.0, 0.1, 0.3 and 0.5) was prepared by the standard solid-state reaction method. The phase formation was checked by synchrotron x-ray diffraction. The structure was refined from the collected x-ray diffraction data using the Reitveld refinement method. The synthesized compositions crystallized mainly in the Pbnm symmetry. The available data in the literature on the structural properties and crystal phase evolution of the solid solution series LaFe1−x
Ni
x
O3 were also analysed critically. We report an anomalous variation in the octahedral deformations in these compositions. In order to explore the composition-dependent microscopic changes driving these structural distortions, we used the refined structural parameters (cell dimensions and atomic coordinates) from our own results and the literature to calculate and see the effects of composition on several structural distortion parameters in an orthorhombic perovskite. Variation of these parameters strongly suggested that incorporation of Ni in LaFeO3 caused the octahedral deformation to increase. However, octahedral tilting decreased with the addition of Ni in LaFeO3. The obtained change in the orthorhombic distortions was caused by the possible presence of Jahn–Teller Fe4+ cations.
RF power dependence of the properties of n-type nanocrystalline silicon films deposited by a low-frequency inductively coupled plasma
Authors: Yan W S , Xu S , Sern C C , Ong T M , Zhou H P
Published: October 2011

Nanocrystalline n-type silicon films are deposited by a low-frequency inductively coupled plasma at a low H2 dilution, low working pressure of 2.0 Pa and low substrate temperature of 150 °C. The radio frequency (RF) power is set in the range 1000–1800 W. The RF power dependence of the structural, optical and electrical properties of the films is systematically studied. The x-ray diffraction patterns of the films present a (1 1 1)-preferred orientation when the RF power is increased from 1000 to 1800 W. The crystalline volume fraction of the films changes from 51% to 82% while the deposition rate of the films increases from 21 to 36 nm min−1. The UV–VIS spectra show that the optical band gap is in the range 1.4–1.6 eV. Two characteristic hydrogen-related modes located at ∼630 and ∼2100 cm−1 are observed. The carrier concentration of the films ranges from 0.9 × 1019 to 1.1 × 1020 cm−3 depending on the applied RF power. When the RF power is increased, the electron density is increased and the Debye length is decreased while the electron temperature remains nearly constant. The doping mechanism of the present n-type nanocrystalline silicon films is revealed.
Effective models of group schemes
Authors: Romagny Matthieu
Published: October 2011

Let

R
R

be a discrete valuation ring with fraction field

K
K

and let

X
X

be a flat

R
R

-scheme. Given a faithful action of a

K
K

-group scheme

G
K

G_K

over the generic fibre

X
K

X_K

, we study models

G
G

of

G
K

G_K

acting on

X
X

. In various situations, we prove that if such a model

G
G

exists, then there exists another model

G
′

G’

that acts faithfully on

X
X

. This model is the schematic closure of

G
G

inside the fppf sheaf

Aut
R

⁡
(
X
)

\operatorname {Aut}_R(X)

; the major difficulty is to prove that it is representable by a scheme. For example, this holds if

X
X

is locally of finite type, separated, flat and pure and

G
G

is finite flat. Pure schemes (a notion recalled in the text) have many nice properties: in particular, we prove that they are the amalgamated sum of their generic fibre and the family of their finite flat closed subschemes. We also provide versions of our results in the setting of formal schemes.
Antarctic killer whales make rapid, round-trip movements to subtropical waters: evidence for physiological maintenance migrations?
Authors: Durban J. W. , Pitman R. L.
Published: October 2011

Killer whales (Orcinus orca) are important predators in high latitudes, where their ecological impact is mediated through their movements. We used satellite telemetry to provide the first evidence of migration for killer whales, characterized by fast (more than 12 km h−1, 6.5 knots) and direct movements away from Antarctic waters by six of 12 type B killer whales tagged when foraging near the Antarctic Peninsula, including all tags transmitting for more than three weeks. Tags on five of these whales revealed consistent movements to subtropical waters (30–37° S) off Uruguay and Brazil, in surface water temperatures ranging from −1.9°C to 24.2°C; one 109 day track documented a non-stop round trip of almost 9400 km (5075 nmi) in just 42 days. Although whales travelled slower in the warmest waters, there was no obvious interruption in swim speed or direction to indicate calving or prolonged feeding. Furthermore, these movements were aseasonal, initiating over 80 days between February and April; one whale returned to within 40 km of the tagging site at the onset of the austral winter in June. We suggest that these movements may represent periodic maintenance migrations, with warmer waters allowing skin regeneration without the high cost of heat loss: a physiological constraint that may also affect other whales.
Assessment of hypoxia-inducible factor-1α mRNA expression in mantis shrimp as a biomarker of environmental hypoxia exposure
Authors: Kodama Keita , Rahman Md. Saydur , Horiguchi Toshihiro , Thomas Peter
Published: October 2011

Efforts to assess the ecological impacts of the marked increase in coastal hypoxia worldwide have been hampered by a lack of biomarkers of hypoxia exposure in marine benthic organisms. Here, we show that hypoxia-inducible factor-1α (HIF-1α) transcript levels in the heart and cerebral ganglion of mantis shrimp (
Oratosquilla oratoria
) collected from hypoxic sites in Tokyo Bay are elevated several-fold over those in shrimp collected from normoxic sites. Upregulation of HIF-1α mRNA levels in the heart after exposure to sub-lethal hypoxia was confirmed in controlled laboratory experiments. HIF-1α transcript levels were increased at approximately threefold after 7 and 14 days of hypoxia exposure and declined to control levels within 24 h of restoration to normoxic conditions. The results provide the first evidence for upregulation of HIF-1α transcript levels in two hypoxia-sensitive organs, heart and cerebral ganglion, in a marine invertebrate exposed to environmental hypoxia. These results suggest that upregulation of HIF-1α transcript levels is an important component in adaptation of mantis shrimp to chronic hypoxia and is a potentially useful biomarker of environmental hypoxia exposure.
Challenges and perspectives for species distribution modelling in the neotropics
Authors: Kamino Luciana H. Y. , Stehmann João Renato , Amaral Silvana , De Marco Paulo , Rangel Thiago F. , de Siqueira Marinez F. , De Giovanni Renato , Hortal Joaquín
Published: October 2011

The workshop ‘
Species distribution models: applications, challenges and perspectives
’ held at Belo Horizonte (Brazil), 29–30 August 2011, aimed to review the state-of-the-art in species distribution modelling (SDM) in the neotropical realm. It brought together researchers in ecology, evolution, biogeography and conservation, with different backgrounds and research interests. The application of SDM in the megadiverse neotropics—where data on species occurrences are scarce—presents several challenges, involving acknowledging the limitations imposed by data quality, including surveys as an integral part of SDM studies, and designing the analyses in accordance with the question investigated. Specific solutions were discussed, and a code of good practice in SDM studies and related field surveys was drafted.
Alan McLeod Sargeson FAA. 13 October 1930 — 29 December 2008
Authors: Bosnich Brice
Published: October 2011

Alan Sargeson was an extraordinarily gifted inorganic chemist who consistently made important and lasting contributions to his discipline. His lifelong interests were in the area of coordination chemistry, especially in the stereochemistry and reactivity of complexes involving the transition element cobalt. Notable discoveries included the elucidation of the mechanisms of substitution reactions of cobalt complexes, the demonstration that amino acid amides and their esters and phosphate esters incorporated in properly designed metal complexes could achieve the high rates of hydrolysis displayed by enzyme reactions, and perhaps most notably the discovery of the ready formation of cage complexes in which the metal is fully encapsulated. His impact on his field was far reaching, his achievements were at the highest level and for more than 30 years he was among the few who dominated the field.
Social network architecture and the maintenance of deleterious cultural traits
Authors: Yeaman Sam , Schick Alana , Lehmann Laurent
Published: October 2011

How have changes in communications technology affected the way that misinformation spreads through a population and persists? To what extent do differences in the architecture of social networks affect the spread of misinformation, relative to the rates and rules by which individuals transmit or eliminate different pieces of information (cultural traits)? Here, we use analytical models and individual-based simulations to study how a ‘cultural load’ of misinformation can be maintained in a population under a balance between social transmission and selective elimination of cultural traits with low intrinsic value. While considerable research has explored how network architecture affects percolation processes, we find that the relative rates at which individuals transmit or eliminate traits can have much more profound impacts on the cultural load than differences in network architecture. In particular, the cultural load is insensitive to correlations between an individual's network degree and rate of elimination when these quantities vary among individuals. Taken together, these results suggest that changes in communications technology may have influenced cultural evolution more strongly through changes in the amount of information flow, rather than the details of who is connected to whom.
Non-random walks in monkeys and humans
Authors: Boyer Denis , Crofoot Margaret C. , Walsh Peter D.
Published: October 2011

Principles of self-organization play an increasingly central role in models of human activity. Notably, individual human displacements exhibit strongly recurrent patterns that are characterized by scaling laws and can be mechanistically modelled as self-attracting walks. Recurrence is not, however, unique to human displacements. Here we report that the mobility patterns of wild capuchin monkeys are not random walks, and they exhibit recurrence properties similar to those of cell phone users, suggesting spatial cognition mechanisms shared with humans. We also show that the highly uneven visitation patterns within monkey home ranges are not entirely self-generated but are forced by spatio-temporal habitat heterogeneities. If models of human mobility are to become useful tools for predictive purposes, they will need to consider the interaction between memory and environmental heterogeneities.
Damped and persistent oscillations in a simple model of cell crawling
Authors: Bayly Philip V. , Taber Larry A. , Carlsson Anders E.
Published: October 2011

A very simple, one-dimensional, discrete, autonomous model of cell crawling is proposed; the model involves only three or four coupled first-order differential equations. This form is sufficient to describe many general features of cell migration, including both steady forward motion and oscillatory progress. Closed-form expressions for crawling speeds and internal forces are obtained in terms of dimensionless parameters that characterize active intracellular processes and the passive mechanical properties of the cell. Two versions of the model are described: a basic cell model with simple elastic coupling between front and rear, which exhibits stable, steady forward crawling after initial transient oscillations have decayed, and a poroelastic model, which can exhibit oscillatory crawling in the steady state.
Vindication of quantum locality
Authors: Deutsch David
Published: October 2011

In a previous paper, Hayden and I (
Deutsch & Hayden 2000
Proc. R. Soc. Lond. A
456
, 1759–1774. (
doi:10.1098/rspa.2000.0585
)) proved, using the Heisenberg picture, that quantum physics satisfies Einstein's criterion of locality. Wallace and Timpson (
Wallace & Timpson 2007
Found. Phys.
37
, 951–955. (
doi:10.1007/s10701-007-9135-7
)) have argued that certain transformations of the Heisenberg-picture description of a quantum system must be regarded as leaving invariant the factual situation being described, and that taking this into account reveals that Einstein's criterion is violated after all. Here, I vindicate the proof and explain some misconceptions that have led to this and other criticisms of it.
Anisotropic surface effects on the formation of chiral morphologies of nanomaterials
Authors: Wang Jian-Shan , Ye Hai-Mu , Qin Qing-Hua , Xu Jun , Feng Xi-Qiao
Published: October 2011

Nanomaterials with chiral morphologies hold promise for a wide diversity of technologically important applications in such fields as micro/nano-electromechanical systems and medical engineering. Understanding the mechanisms underlying the formation of chiral morphologies of natural and synthesized materials remains an issue of crucial significance. In this study, a refined Kirchhoff rod model taking into account anisotropic surface effects is employed to describe quasi-one-dimensional nanomaterials with complicated spatial morphologies. It is shown that anisotropic surface stresses can induce the formation of rich morphologies of nanomaterials. A general shape equation of nanowires is derived by the variational method of energy. Thereby, the effects of anisotropic surface properties, bulk elastic properties and cross-sectional sizes on the chiral morphologies of nanomaterials are quantitatively investigated, and the conditions for the formation of binormal nanohelices are given. The physical mechanism addressed in this study is verified by our recent experiments on tuning the twisting chirality of polymer lamellae via surface treatments. Our analysis suggests that one can design and adjust the morphology of synthesized nanohelices by tailoring or functionalizing their surfaces during fabrication. This study is also helpful in interpreting the formation of such artificial and biological chiral materials as the flagella of bacterial and self-assembled helical ribbons.
Update on Chemotherapy in the Treatment of Urothelial Carcinoma
Authors: Costantini Carrie , Millard Frederick
Published: October 2011

Urothelial carcinoma is the fifth most common malignancy diagnosed each year in the United States. Neoadjuvant and adjuvant chemotherapy are given to decrease the risk of recurrent or metastatic disease with the more robust clinical data supporting the former. Bladder preservation utilizes a trimodality approach with maximal transurethral resection followed by concurrent chemotherapy and radiation and is appropriate for select patients. Gemcitabine and cisplatin is the current standard of care for first-line treatment in fit patients with metastatic disease. Optimal second-line therapy remains undefined, and targeted agents are under investigation. Clinical trial participation should be encouraged in patients with urothelial carcinoma of the bladder to help improve treatment regimens and outcomes.Synopsis. Chemotherapy is commonly used in the treatment of urothelial carcinoma of the bladder. This paper will review the role of chemotherapy in the neoadjuvant, adjuvant, bladder sparing, and metastatic settings.
Emission Inventory for PFOS in China: Review of Past Methodologies and Suggestions
Authors: Lim Theodore Chao , Wang Bin , Huang Jun , Deng Shubo , Yu Gang
Published: October 2011

Perfluorooctane sulfonate (PFOS) is a persistent, bioaccumulative, and toxic chemical that has the potential for long-range transport in the environment. Its use in a wide variety of consumer products and industrial processes makes a detailed characterization of its emissions sources very challenging. These varied emissions sources all contribute to PFOS' existence within nearly all environmental media. Currently, China is the only country documented to still be producing PFOS, though there is no China PFOS emission inventory available. This study reviews the inventory methodologies for PFOS in other countries to suggest a China-specific methodology framework for a PFOS emission inventory. The suggested framework combines unknowns for PFOS-containing product penetration into the Chinese market with product lifecycle assumptions, centralizing these diverse sources into municipal sewage treatment plants. Releases from industrial sources can be quantified separately using another set of emission factors. Industrial sources likely to be relevant to the Chinese environment are identified.
Memory consolidation in both trace and delay fear conditioning is disrupted by intra-amygdala infusion of the protein synthesis inhibitor anisomycin
Authors: Kwapis Janine L. , Jarome Timothy J. , Schiff Janet C. , Helmstetter Fred J.
Published: October 2011

Memory for delay fear conditioning requires the synthesis of new mRNA and protein in the basolateral amygdala. It is currently unknown whether similar molecular processes in the amygdala are required for the formation of trace fear memory, in which a stimulus-free interval is inserted between the conditional stimulus (CS) and unconditional stimulus (UCS). Here, we show that infusion of the protein synthesis inhibitor anisomycin into the basolateral amygdala disrupts consolidation of both trace and delay fear conditioning. This is the first evidence that protein synthesis in the amygdala is necessary for the formation of both trace and delay fear memory.
Randomized trial of standard methadone treatment compared to initiating methadone without counseling: 12‐month findings
Authors: Schwartz Robert P. , Kelly Sharon M. , O'Grady Kevin E. , Gandhi Devang , Jaffe Jerome H.
Published: October 2011

Aims  This study aimed to determine the relative effectiveness of 12 months of interim methadone (IM; supervised methadone with emergency counseling only for the first 4 months of treatment), standard methadone treatment (SM; with routine counseling) and restored methadone treatment (RM: routine counseling with smaller case‐loads).

Design  A randomized controlled trial was conducted comparing IM, SM and RM treatment. IM lasted for 4 months, after which participants were transferred to SM.

Setting  The study was conducted in two methadone treatment programs in Baltimore, MD, USA.

Participants  The study included 230 adult methadone patients newly admitted through waiting‐lists.

Measurements  We administered the Addiction Severity Index and a supplemental questionnaire at baseline, 4 and 12 months post‐ baseline. Measurements included retention in treatment, self‐reported days of heroin and cocaine use, criminal behavior and arrests and urine tests for heroin and cocaine metabolites.

Findings  At 12 months, on an intent‐to‐treat basis, there were no significant differences in retention in treatment among the IM, SM and RM groups (60.6%, 54.8% and 37.0%, respectively). Positive urine tests for the three groups declined significantly from baseline (Ps < 0.001 and 0.003, for heroin and cocaine metabolites, respectively) but there were no significant group x time interactions for these measures. At least one arrest was reported by 30.6% of the sample during the year, but there were no significant between‐group effects.

Conclusions  Limited availability of drug counseling services should not be a barrier to providing supervised methadone to adults dependent on heroin—at least for the first 4 months of treatment.
Sexual conflict in mammals: consequences for mating systems and life history
Authors: Aloise King Edith D. , Banks Peter B. , Brooks Robert C.
Published: October 2011

Sexual conflict theory suggests that male and female interests often diverge, causing selection to favour sex‐specific reproductive strategies that maximize the fitness of an individual at the expense of its mate. Sexually antagonistic selection can lead to conflicts over the timing and frequency of mating events, mate choice and the delivery of parental care.

This antagonistic view of reproduction has received little attention in discussions of the evolution of mammalian mating systems. Reproduction in mammals, more than in other organisms, is characterized by asymmetry in parental investment between the sexes. This asymmetry provides opportunities for sexual conflict to manifest itself.

We highlight the potential for sexual conflict in mammalian mating systems by exploring why males and females are selected to mate with multiple partners and by considering the shared characteristics of mammalian reproductive biology that may lead to predictable patterns of conflict over parental investment.

The degree to which sexual conflict is realized as sexually antagonistic adaptations may vary between species, depending on the strength of selection for multiple mating, paternity assurance and the amount of parental care required.

Empirical evidence of sexual conflict in mammalian species is needed. Available genomic and phylogenetic tools, and the identification of mating, placentation, lactation and parental care as likely sites of conflict, make mammals a natural choice for research. Understanding the factors that influence the magnitude of the conflict and the ways in which conflict shapes male and female adaptations and counter‐adaptations should be priorities.

The integration of sexual conflict theory into models of mammalian life history evolution will unify developments in behavioural ecology, physiology, genetics and genomics. This multidisciplinary approach may reveal novel ways in which sexual conflict can operate, and increase understanding of evolution.
Magnetosome chains are recruited to cellular division sites and split by asymmetric septation
Authors: Katzmann Emanuel , Müller Frank D. , Lang Claus , Messerer Maxim , Winklhofer Michael , Plitzko Jürgen M. , Schüler Dirk
Published: October 2011

Magnetotactic bacteria navigate along magnetic field lines using well‐ordered chains of membrane‐enclosed magnetic crystals, referred to as magnetosomes, which have emerged as model to investigate organelle biogenesis in prokaryotic systems. To become divided and segregated faithfully during cytokinesis, the magnetosome chain has to be properly positioned, cleaved and separated against intrachain magnetostatic forces. Here we demonstrate that magnetotactic bacteria use dedicated mechanisms to control the position and division of the magnetosome chain, thus maintaining magnetic orientation throughout divisional cycle. Using electron and time‐lapse microscopy of synchronized cells of Magnetospirillum gryphiswaldense, we confirm that magnetosome chains undergo a dynamic pole‐to‐midcell translocation during cytokinesis. Nascent chains were recruited to division sites also in division‐inhibited cells, but not in a mamK mutant, indicating an active mechanism depending upon the actin‐like cytoskeletal magnetosome filament. Cryo‐electron tomography revealed that both the magnetosome chain and the magnetosome filament are spilt into halves by asymmetric septation and unidirectional indentation, which we interpret in terms of a specific adaptation required to overcome the magnetostatic interactions between separating daughter chains. Our study demonstrates that magnetosome division and segregation is co‐ordinated with cytokinesis and resembles partitioning mechanisms of other organelles and macromolecular complexes in bacteria.
A physical approach to segregation and folding of the Caulobacter crescentus genome
Authors: Dame Remus T. , Tark‐Dame Mariliis , Schiessel Helmut
Published: October 2011

Bacterial genomes are functionally organized. This organization is dynamic and globally changing throughout the cell cycle. Upon initiation of replication of the chromosome, the two origins segregate and move towards their new location taking along the newly replicated genome. Caulobacter crescentus employs a dedicated active partitioning (Par) system to move one copy of the parS centromere to the distal pole, while the other stays at the stalked pole. In this issue of Molecular Microbiology, Hong and McAdams describe studies on the speed of segregation of parS and regions up to 150 kb away. They show clear differences in segregation rates between parS and 50 kb flanking regions versus regions further away. To assess segregation rates the authors track fluorescent markers during movement using time‐lapse microscopy. The relation between genomic and physical distance of pairs of markers reflects how the genome is folded. This relation permits testing experimental data against models from polymer physics. Such models are helpful in understanding principles of genome folding. Although long used in studies on eukaryotes, this approach has rarely been applied to bacteria. Finally, the authors give the first direct evidence for a role of the bacterial chromatin protein HU in folding the genome in vivo.