bluuebunny/crossref_metadata_2025 huggingface dataset:
Systemic therapy of disseminated malignant melanoma: an evidence‐based overview of the state‐of‐the‐art in daily routine
Authors: Nashan D , Müller ML , Grabbe S , Wustlich S , Enk A
Published: October 2007

Aims  In the metastatic stage, malignant melanoma is resistant to systemic treatment and carries a poor prognosis. A critical, evidence‐based analysis of standard approaches based on an extended search of published literature and from different Internet sources is presented.

Material and methods  A critical, evidence‐based analysis of standard approaches and their variations to systemic therapy based on an extended search of published literature and from different Internet sources is presented. Few meta‐analyses are available. Therefore, assessment of therapies is mainly based on randomized multicentre studies or clinical studies achieving an evidence level grade 1 or 2.

Results  Monotherapy with DTIC (dacarbazine) is the standard. Based on overall survival data, polychemotherapies cannot be recommended. Combination of polychemotherapy with the cytokines interferon‐α and interleukin‐2 substantially augments chemotherapy induced response rates, but a meta‐analysis for survival does not support its therapeutic superiority. Biological therapies such as vaccinations have not yet delivered results on a higher evidence level. Thus, immunotherapies as well as chemo‐immunotherapies will have to be evaluated in further studies.

Conclusions  Although the therapeutic efficacy is very limited, dacarbazine cannot be rejected as standard therapy for disseminated melanoma, because no other therapeutic regimen exhibits a survival benefit over DTIC in an evidence‐based analysis. This lack of therapeutic progress over the past 40 years clearly calls for further clinical studies, and patients should be enrolled into clinical trials whenever possible.
Preload Dependence of the Time Interval between Onsets of Mitral Inflow and Early Diastolic Mitral Annular Velocity: A Study in Healthy Subjects
Authors: Lubanda Jean‐Claude Mukonkole , Palecek Tomas , Trckova Radka , Wilson James Michael , Linhart Ales
Published: October 2007

The time interval (TEa–E) between onsets of early diastolic mitral annular velocity (Ea) and early mitral inflow velocity (E) has been proposed as a new index of left ventricular (LV) relaxation. We aimed to assess the influence of preload changes on this parameter by examining 25 healthy volunteers at rest, after passive leg lifting, and after administration of nitroglycerin combined with Valsalva maneuver. To obtain septal and lateral TEa–E, the time intervals between peak R‐wave on electrocardiogram and the onsets of Ea and E were measured in different cardiac cycles. E and Ea were significantly changed by preload manipulations. We did not observe significant changes of TEa–E intervals after leg lifting or after nitroglycerin administration combined with Valsalva maneuver (P = NS). TEa–E was < 0 ms in several subjects using either septal or lateral Ea recordings. We conclude that TEa–E may be load independent in subjects with normal LV systolic and diastolic function as compared to other Doppler parameters. Therefore, this index could be potentially used as a reliable noninvasive parameter of LV relaxation. Nevertheless, even slight differences in cardiac cycle lengths might influence the measurements of TEa–E interval. For that reason, the clinical use of TEa–E seems to be significantly limited because of a wide margin of error in its measurement due to the inability to obtain Doppler recordings during the same cardiac cycle.
Ridge augmentation by applying bioresorbable membranes and deproteinized bovine bone mineral: a report of twelve consecutive cases
Authors: Hämmerle Christoph H. F. , Jung Ronald E. , Yaman Duygu , Lang Niklaus P.
Published: October 2007

Objective: Lateral ridge augmentations are traditionally performed using autogenous bone grafts to support membranes for guided bone regeneration (GBR). The bone‐harvesting procedure, however, is accompanied by considerable patient morbidity.

Aim: The aim of the present study was to test whether or not resorbable membranes and bone substitutes will lead to successful horizontal ridge augmentation allowing implant installation under standard conditions.

Material and methods: Twelve patients in need of implant therapy participated in this study. They revealed bone deficits in the areas intended for implant placement. Soft tissue flaps were carefully raised and blocks or particles of deproteinized bovine bone mineral (DBBM) (Bio‐Oss®) were placed in the defect area. A collagenous membrane (Bio‐Gide®) was applied to cover the DBBM and was fixed to the surrounding bone using poly‐lactic acid pins. The flaps were sutured to allow for healing by primary intention.

Results: All sites in the 12 patients healed uneventfully. No flap dehiscences and no exposures of membranes were observed. Nine to 10 months following augmentation surgery, flaps were raised in order to visualize the outcomes of the augmentation. An integration of the DBBM particles into the newly formed bone was consistently observed. Merely on the surface of the new bone, some pieces of the grafting material were only partly integrated into bone. However, these were not encapsulated by connective tissue but rather anchored into the newly regenerated bone. In all of the cases, but one, the bone volume following regeneration was adequate to place implants in a prosthetically ideal position and according to the standard protocol with complete bone coverage of the surface intended for osseointegration. Before the regenerative procedure, the average crestal bone width was 3.2 mm and to 6.9 mm at the time of implant placement. This difference was statistically significant (P<0.05, Wilcoxon's matched pairs signed‐rank test).

Conclusion: After a healing period of 9–10 months, the combination of DBBM and a collagen membrane is an effective treatment option for horizontal bone augmentation before implant placement.
Esthetic outcomes of immediate implant placements
Authors: Evans Christopher D. J. , Chen Stephen T.
Published: October 2007

Background: Single‐rooted teeth deemed not restorable via conventional means may be candidates for implant placement at the time of tooth extraction. Immediate implant placements are believed to preserve soft and hard tissue form and contours, reduce the need for augmentation procedures, minimize surgical exposure of the patient, reduce treatment time and improve esthetic outcomes.

Method: This retrospective review analyzed the esthetic outcomes of 42 non‐adjacent single‐unit implant restorations completed using an immediate implant surgical placement protocol.

Results: The mean time in function was 18.9 months (range 6–50 months) and the majority of implants placed had a restorative platform diameter of 4.1 and 4.8 mm. A highly significant change in crown height due to marginal tissue recession of 0.9 ± 0.78 mm (P=0.000) was recorded for all sites, with no difference seen between implant systems (P=0.837). Thin tissue biotype showed slightly greater recession than thick tissue biotype (1 ± 0.9 vs. 0.7 ± 0.57 mm, respectively); however, this difference was not statistically significant (P=0.187). Implants with a buccal shoulder position showed three times more recession than implants with a lingual shoulder position (1.8 ± 0.83 vs. 0.6 ± 0.55 mm, respectively) with the difference being highly statistically significant (P=0.000).

Conclusions: Immediate implant placement requires very careful case selection and high surgical skill levels if esthetic outcomes are to be achieved. Long‐term prospective studies on tissue stability and esthetic outcomes are needed.
Root contact during insertion of miniscrews for orthodontic anchorage increases the failure rate: an animal study
Authors: Chen Yuan‐Hou , Chang Hao‐Hueng , Chen Yi‐Jane , Lee David , Chiang Hsien‐Hsiung , Jane Yao Chung‐Chen
Published: October 2007

Objectives: Miniscrews and miniplates are increasingly being used for absolute anchorage during orthodontic treatment. However, potential problems of damaging adjacent roots and their consequences during mini‐implant placement in the alveolar process have not been clearly described.

Materials and methods: Animal experiments were used to evaluate the stability of miniscrews placed with intentional root contact. The root repair was evaluated after screw removal. Seventy‐two miniscrews were surgically placed in the mandibular alveolar bone of six adult mongrel dogs with metabolic bone labeling at 3‐week intervals. Miniscrews of the experimental group were placed so that they contacted the root of the adjacent teeth, were retained for different time durations, and were then removed. The insertion torque, clinical measurements, removal torque, and histological findings were analyzed.

Results: (1) miniscrews contacting the roots showed a significantly higher insertion torque than those without contact; (2) there was a significant difference in the removal torque measurements based on the mobility of miniscrews and the state of root contact; and (3) miniscrews contacting the root were at greater risk of failure.

Conclusions: During placement of miniscrews in the aveolar process, increased failure rates were noticed among those contacting adjacent roots. Failed miniscrews appeared to be surrounded with a greater volume of soft tissue. When more inflammation was present, the adjacent roots seemed to experience more resorption. Nevertheless, the created lesion was repaired with a narrow zone of mineralized tissue deposited on the root surface, which was likely cellular cementum, and was mainly filled with alveolar bone, with the periodontal ligament space being maintained.
In vitro osteogenesis induced by cells derived from sites submitted to sinus grafting with anorganic bovine bone
Authors: Beloti Marcio Mateus , Martins Walter , Xavier Samuel Porfirio , Rosa Adalberto Luiz
Published: October 2007

Objectives: This study evaluated key parameters of the in vitro osteogenesis induced by osteoblastic cells obtained from sites submitted to sinus grafting with anorganic bovine bone (ABB) in comparison with cells derived from bone sites of the same patients.

Materials and methods: In three patients, the augmentation of maxillary sinus was carried out using ABB (Bio‐Oss®). After at least 6 months, during the surgical intervention for titanium implants placement, biopsies were taken from these areas using trephine burs (grafted group). Bone fragments, of the same patients, from sites that had not received graft were also obtained with trephine burs and used as a control group. Osteoblastic cells were obtained from grafted and control groups by enzymatic digestion and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured in 24‐well culture plates. Cell adhesion was evaluated at 24 h. For proliferation and viability assay, cells were cultured for 1, 3, 7, and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 3, 7, 10, 14, 17, and 21 days. Cultures were stained with Alizarin red S at 21 days, for detection of mineralized matrix. Data were compared by Student's t‐test.

Results: Cell adhesion and viability were not affected by cell source (P>0.05). Total protein content was greater (P<0.05) for grafted group. Cell proliferation, ALP activity, and bone‐like nodule formation were all greater (P<0.05) for the control group.

Conclusion: Taken together, these results indicate that the in vivo long‐term contact of cells with ABB downregulates the expression of osteoblast phenotype and consequently the in vitro osteogenesis.
Immediate loading of single SLA implants: drilling vs. osteotomes for the preparation of the implant site
Authors: Stavropoulos Andreas , Nyengaard Jens R. , Lang Niklaus P. , Karring Thorkild
Published: October 2007

Objectives: To evaluate whether or not preparation of the implant site with osteotomes instead of drilling may improve peri‐implant bone density and/or osseointegration, and whether or not this further improves the predictability of immediate loading of SLA implants.

Material and methods: The second, third, and fourth premolars were extracted in both sides of the mandible in six dogs, and after at least 3 months four SLA implants were inserted into each side of the jaw. In three animals, the implant sites were prepared by means of osteotomes, while standard stepwise drilling was used in the remaining animals. In each side of the jaw, two non‐adjacent implants were restored with single crowns 4 days after installation, while the remaining two implants were left without crowns to serve as non‐loaded controls. After 2, 4, or 12 weeks of loading, specimens including the implants and surrounding tissues were obtained and processed for histologic analysis of undecalcified sections.

Results: All implants placed with osteotomes were lost (five before delivery of the crowns and the rest during the first week after loading). None of the conventionally inserted implants, however, was lost, and histomorphometrical analysis revealed similar soft‐ and hard peri‐implant tissue characteristics at immediately loaded and non‐loaded implants at all observation times. Average bone‐to‐implant contact was 59–72% at immediately loaded implants vs. 60–63% at non‐loaded ones.

Conclusion: Preparation of the implant site by means of osteotomes had a deleterious effect on osseointegration, while immediate loading of single, free‐standing, SLA implants following a conventional surgical protocol did not jeopardize their osseointegration.
A model study on flapless implant placement by clinicians with a different experience level in implant surgery
Authors: Van de Velde Tommie , Glor Fadi , De Bruyn Hugo
Published: October 2007

Introduction: Some implant companies advocate that flapless surgery is easy to perform and beneficial for aesthetics and patients morbidity. However, studies objectively analyzing the position in the bone of implants installed with this approach are lacking. This in vitro model study was performed to analyse deviations in position and inclination of implants placed with flapless surgery compared with the ideally planned position and to examine whether the outcome is affected by experience level.

Methods: Identical radio‐opaque resin models were developed with a silicon lining mimicking the soft tissues and six edentulous single tooth spaces. Eighteen clinicians (six periodontists, six general dentists and six students) drilled four implant sites each (Straumann AG, Basel, Switzerland) with a flapless approach. Corresponding CT‐scan images of the models were available. A virtual implant program (Simplant, Materialise NV, Leuven, Belgium) was used to plan the ideal position and to compare this with the implant angulation and position of the test implants.

Results: There were no significant differences between the experience groups for all parameters except for global deviations between dentist and students, angle deviations between dentists and students and horizontal deviations between specialists and students.

In incisor sites, specialists and students deviated significantly more in global deviation and depth than dentists. In premolar and molar sites, there were no significant differences except for horizontal deviations between specialists and dentists in molar sites. As a consequence of the malpositioning, perforations were seen in 59.7% (43/72) of the implant occasions when the artificial mucosa was removed from the model.

Conclusion: The three‐dimensional location of implants installed with flapless approach differs significantly from the ideal, although neighbouring teeth were present and maximal radiographical information was available. Within the limitations of this in vitro model study it seems necessary to point out that these deviations would in a clinical situation lead to complications such as loss of implant stability, aesthetical and phonetical consequences. The outcome is not influenced by the level of experience with implant surgery. This points out that more precise measurements of soft tissue in situ or additional use of guiding systems are recommendable.
Social and cultural dimensions of rodent pest management
Authors: PALIS Florencia G. , SINGLETON Grant , SUMALDE Zenaida , HOSSAIN Mahabub
Published: October 2007

Rice production in Vietnam is threatened by rodent pests, with a significant increase in impact reported from 1990 through to the early 21st century. Pre‐harvest rice losses are typically 5–10%, with losses of >20% occurring in some years in some regions. Farmers' rodent control practices are generally reactive and rely essentially on chemical and physical methods. Ecologically‐based rodent pest management (EBRM) was developed in the late 1990s to manage rodents in rice‐based farming systems in Vietnam and other parts of South‐East Asia. EBRM combines both cultural and physical rodent management practices such as synchrony of cropping, short 2‐week rat campaigns at key periods in key habitats, increasing general hygiene around villages, and use of a community trap‐barrier system. Although EBRM has been reported to be economically profitable, the successful adoption of this set of technologies requires community participation. In this paper we address issues relating to the adoption and sustainability of EBRM in lowland irrigated rice fields in the Mekong Delta in Vietnam. We particularly explore the social and cultural mechanisms involved in maintaining community participation to further understand the conditions under which EBRM works and does not work. Positive indications of sustained use of community‐based EBRM include: a policy pronouncement from the prime minister directing the use of integrated rodent management; the use of existing cooperatives for developing community actions; budgetary allocation from provincial and local governments; diffusion of EBRM to provinces in the south and north that are not involved in farmer participatory field trials; and the adoption of EBRM by a non‐governmental organization, World Vision Vietnam, in their area‐development programs.
Optimal offspring provisioning when egg size is “constrained”: a case study with the painted turtle Chrysemys picta
Authors: Rollinson Njal , Brooks Ronald J.
Published: October 2007

Classic egg size theory predicts that, in a given environment, there is a level of maternal investment per offspring that will maximize maternal fitness. However, positive correlations among egg size and female body size are observed within populations in diverse animal taxa. A popular explanation for this phenomenon is that, in some populations, morphological constraints on egg size, such as ovipositor size (insects) or pelvic aperture width (lizards and turtles), limit egg size. Egg size may therefore increase with female body size due to body size‐specific constraints on investment per offspring, coupled with selection towards an optimal egg size. We use 17 years of data from a population of painted turtles Chrysemys picta to evaluate this hypothesis. In accordance with our predictions, we find that (1) morphological constraints on egg size are apparent only in relatively small females, similarly (2) egg mass exhibits a strong asymptotic relationship with female body size, suggesting egg mass is optimized only at large body sizes, (3) clutch size, not egg mass, varies with female condition, and (4) clutch size varies more than egg mass across years. Contrary to our predictions, we observe that (5) the egg mass‐clutch size tradeoff is not less pronounced at large body sizes. Our data do not fully support the traditional hypothesis, and recent models suggest that this hypothesis is indeed overly simplistic. When the selective environment of a female's offspring is influenced by her phenotype, optimal egg size may vary among maternal phenotypes. This concept can explain correlations among egg size and body size in many taxa, as well as the patterns observed in the present study. In this paradigm, a tight coupling of aperture width (or other ‘constraints’) and egg size may occur in small females, even when such morphological features are not causally related to variation in egg size. In this spirit, we question validity of invoking morphological constraints to explain covariation among egg size and female body size.
Extinction risks in metapopulations of a beetle inhabiting hollow trees predicted from time series
Authors: Ranius Thomas
Published: October 2007

Ancient and dead trees are declining habitats harbouring many threatened species. These habitats are naturally patchy, and inhabiting species might exhibit metapopulation dynamics at a small spatial scale. In this study, the demography and metapopulation dynamics was analysed forOsmoderma eremita, which is an endangered beetle species associated with tree hollows in Europe. Extinction risks ofO. eremitapopulations were predicted using Monte Carlo simulations based on time series of population assessments. Predicted occurrence patterns were consistent with field observations from an area with many small stands in which the populations are believed to have been more or less isolated from each other during the last 150–200 yr. Population growth was found to be density dependent. Carrying capacity was proportional to the volume of wood mould (i.e. loose material of dead wood in the tree hollows), which varied widely between hollow trees. This generates large differences in local extinction risks between hollow trees. The predicted metapopulation extinction risk was much higher if the habitat dynamics (formation, gradual increase and deterioration of tree hollows) were taken into consideration than in predictions yielded by models in which the amount of wood mould was assumed to be constant over time. Thus, this system has features from both mainland‐island metapopulations and habitat‐tracking metapopulations, and is rather far from a classic metapopulation. For the long‐term persistence of the species in hollow trees, the habitat dynamics seem to be more important than demographic processes. Since the formation and deterioration of suitable tree are partly stochastic processes, there is a considerable extinction risk for manyO. eremitapopulations, because they mainly rely on only one or a few trees with large amounts of wood mould.
No effect of habitat fragmentation on post‐fledging, first‐year and adult survival in the middle spotted woodpecker
Authors: Robles Hugo , Ciudad Carlos , Vera Rubén , Baglione Vittorio
Published: October 2007

Despite its relevance for the dynamics of populations, the ecological mechanisms underlying juvenile and adult survival are poorly known in most bird species. This study focuses on the effect of habitat fragmentation on early post‐fledging, first‐year and adult survival of the middle spotted woodpecker Dendrocopus medius by combining data of radio‐tagged and ringed birds. Among juveniles, most deaths occurred during the first three weeks after fledging (survival rate: 0.359±0.077) and were mainly caused by predation. After independence, birds faced another critical period during their first autumn‐winter that lowered first‐year survival further (0.255±0.044), whereas adult mortality was considerably lower (annual survival rate: 0.786±0.074). We did not find any significant effect of habitat fragmentation (measured as patch size and connectivity) on juvenile or adult survival. Sex ratio at fledging did not differ significantly from parity (proportion of females: 0.513) and was not correlated to patch size. Regardless of age, survival did not differ between the sexes, suggesting that a female‐biased mortality was not the mechanism behind the presence of unpaired territorial males in this population. Lighter nestlings underwent significantly higher post‐fledging mortality, indicating that conditions in the nest may substantially affect survival later in life.
Characterising the temporal variability of the spatial distribution of animals: an application to seabirds at sea
Authors: Certain Grégoire , Bellier Edwige , Planque Benjamin , Bretagnolle Vincent
Published: October 2007

Understanding the patterns of spatial and temporal variations in animal abundance is a fundamental question in ecology. Here, we propose a method to quantify temporal variations in animal spatial patterns and to determine the spatial scale at which such temporal variability is expressed. The methodology extends from the approach proposed by Taylor (Taylor, L. R. 1961. Aggregation, variance and the mean. Nature 189: 732–735) and relies on models of the relationship between temporal mean and variance in animal abundance. Repeated observations of the spatial distribution of populations are used to construct spatially explicit models of Taylor's power law. The resulting slope parameters of the Taylor power law provide local measures of the temporal variability in animal abundance. We investigate if the value of the slope varies significantly with spatial location and with spatial scale. The method is applied to seabirds distribution in the Bay of Biscay. We study four taxa (northern gannets, large gulls, auks and kittiwakes) that display distinct geographical distribution, spatial structure and foraging strategy. Our results show that the temporal variability associated to the spatial distribution of northern gannets is high and spatially homogeneous. By contrast, kittiwakes present large geographical areas associated with high and low variability. The temporal variability of auk's spatial distribution is strongly scale‐dependent: at fine scale high variability is associated to high abundance, but at large scale high variability is associated to the external border of their distribution range. The method provides satisfactory results and useful information on species spatio‐temporal distribution.
Quaternary climate changes explain diversity among reptiles and amphibians
Authors: Araújo Miguel B. , Nogués‐Bravo David , Diniz‐Filho José Alexandre F. , Haywood Alan M. , Valdes Paul J. , Rahbek Carsten
Published: October 2007

It is widely believed that contemporary climate determines large‐scale patterns of species richness. An alternative view proposes that species richness reflects biotic responses to historic climate changes. These competing “contemporary climate” vs “historic climate” hypotheses have been vigorously debated without reaching consensus. Here, we test the proposition that European species richness of reptiles and amphibians is driven by climate changes in the Quaternary. We find that climate stability between the Last Glacial Maximum (LGM) and the present day is a better predictor of species richness than contemporary climate; and that the 0°C isotherm of the LGM delimits the distributions of narrow‐ranging species, whereas the current 0°C isotherm limits the distributions of wide‐ranging species. Our analyses contradict previous studies of large‐scale species richness patterns and support the view that “historic climate” can contribute to current species richness independently of and at least as much as contemporary climate.
Prey size and ingestion rate in raptors: importance for sex roles and reversed sexual size dimorphism
Authors: Slagsvold Tore , A. Sonerud Geir
Published: October 2007

Compared to other birds, most raptors take large prey for their size, and feeding bouts are extended. However, ingestion rate has largely been overlooked as a constraint in raptors′ foraging and breeding ecology. We measured ingestion rate by offering avian and mammalian prey to eighteen wild raptors temporarily kept in captivity, representing seven species and three orders. Ingestion rate was higher for small than for large prey, higher for mammalian than for avian prey, higher for large than for small raptors, and higher for wide‐gaped than for narrow‐gaped raptors. Mammalian prey were ingested faster by raptors belonging to species with mainly mammals in their diet than by raptors with mainly birds in their diet, but the drop in ingestion rate with increasing prey size was more rapid for the former than for the latter. We argue that the separate sex roles found in raptors, i.e. the male hunting and the female feeding the young, is a solution of the conflict between the prolonged feeding bouts at the nest, and the benefit of rapid resumption of hunting in general, and rapid return to the previous capture site in particular (the prey size hypothesis). Thus, the sex roles differ more when prey takes longer to feed, i.e. from insects to mammals to birds. We then argue that the reversed sexual size dimorphism in raptors, i.e. smaller males than females, results from a conflict between the benefit of being small during breeding to capture the smallest items with the highest ingestion rate among these agile prey types (mammals and bird), and the benefit of being large outside the breeding season to ensure survival by being able to include large items in the diet when small items are scarce (the ingestion rate hypothesis). This hypothesis explains the observed variation in reversed sexual size dimorphism among raptors in relation to size and type of prey, i.e. increasing RSD from insects to mammals to birds as prey.
Variation in the hematocrit of a passerine bird across life stages is mainly of environmental origin
Authors: Potti Jaime
Published: October 2007

The heritability of the hematocrit in adult, breeding pied flycatchers Ficedula hypoleuca is examined in a southern European population across seven years to see the consistency, or lack thereof, of patterns found with the trait at fledgling age where no significant heritability could be detected. While the across‐years repeatability of the trait in adult, breeding birds was low but significant, heritabilities based on adult parent‐adult offspring regressions controlling for assortative mating and full‐sibling comparisons did not differ significantly from zero. Neither were heritability estimates affected by selection on fledgling hematocrit, as it was unrelated to local recruitment. There was no relationship between fledgling and adult hematocrit, suggesting that both behave as phenotypically plastic, different traits. This is the first study testing for the heritability of a physiological trait in birds with data from adult, free‐ranging individuals.
Within‐brood size differences affect innate and acquired immunity in rollerCoracias garrulusnestlings
Authors: Parejo Deseada , Silva Nadia , Avilés Jesús M.
Published: October 2007

The immune system has a crucial importance determining animal health and survival. Its maintenance and activation are costly and usually trade with other physiologically costly functions. In birds, number and size of siblings in a nest are likely to determine the development of immunity. Indeed lower immunocompetence is expected in large than in small broods. Moreover, in asynchronous breeders, siblings are expected to differ in immunocompetence because asynchrony produces marked size hierarchy within‐broods. Here we studied the effect of environmental conditions at the nest, chick sex and size, and natural mass differences among siblings due to hatching asynchrony on the development of the innate and acquired immune systems in the threatened non‐size dimorphic asynchronous breeder European rollerCoracias garrulus. Constitutive innate immune function was estimated by using a new technique proposed byMatson et al. (2005). Natural Antibody (NAb) and Complement levels, innate immunity, varied with the mass difference between each chick and its heaviest sibling. NAb levels were higher in late‐hatched siblings compared to early‐hatched ones, indicating that the smallest offspring in each brood has the most developed innate immune system. This relationship was independent of the nest environment. The heterophil/lymphocyte (H/L) ratio, which may indicate the level of stress, was higher in the heaviest siblings of each brood. In addition, the H/L ratio and white blood cell count (WBC) of nestlings, measures belonging to both the innate and acquired arms of the immune system, were related to conditions suffered in the nest. Our results may be explained by differential allocation of resources by female rollers as a way to improve the survival of the whole brood.
Direction selectivity in V1 of alert monkeys: evidence for parallel pathways for motion processing
Authors: Gur Moshe , Snodderly D. Max
Published: October 2007

In primary visual cortex (V1) of macaque monkeys, motion selective cells form three parallel pathways. Two sets of direction selective cells, one in layer 4B, and the other in layer 6, send parallel direct outputs to area MT in the dorsal cortical stream. We show that these two outputs carry different types of spatial information. Direction selective cells in layer 4B have smaller receptive fields than those in layer 6, and layer 4B cells are more selective for orientation. We present evidence for a third direction selective pathway that flows through V1 layers 4Cm (the middle tier of layer 4C) to layer 3. Cells in layer 3 are very selective for orientation, have the smallest receptive fields in V1, and send direct outputs to area V2. Layer 3 neurons are well suited to contribute to detection and recognition of small objects by the ventral cortical stream, as well as to sense subtle motions within objects, such as changes in facial expressions.
Differential modulation of short‐term synaptic dynamics by long‐term potentiation at mouse hippocampal mossy fibre synapses
Authors: Gundlfinger Anja , Leibold Christian , Gebert Katja , Moisel Marion , Schmitz Dietmar , Kempter Richard
Published: October 2007

Synapses continuously experience short‐ and long‐lasting activity‐dependent changes in synaptic strength. Long‐term plasticity refers to persistent alterations in synaptic efficacy, whereas short‐term plasticity (STP) reflects the instantaneous and reversible modulation of synaptic strength in response to varying presynaptic stimuli. The hippocampal mossy fibre synapse onto CA3 pyramidal cells is known to exhibit both a presynaptic, NMDA receptor‐independent form of long‐term potentiation (LTP) and a pronounced form of STP. A detailed description of their exact interdependence is, however, lacking. Here, using electrophysiological and computational techniques, we have developed a descriptive model of transmission dynamics to quantify plasticity at the mossy fibre synapse. STP at this synapse is best described by two facilitatory processes acting on time‐scales of a few hundred milliseconds and about 10 s. We find that these distinct types of facilitation are differentially influenced by LTP such that the impact of the fast process is weakened as compared to that of the slow process. This attenuation is reflected by a selective decrease of not only the amplitude but also the time constant of the fast facilitation. We henceforth argue that LTP, involving a modulation of parameters determining both amplitude and time course of STP, serves as a mechanism to adapt the mossy fibre synapse to its temporal input.
Physical (in)activity and endothelium‐derived constricting factors: overlooked adaptations
Authors: Thijssen D. H. J. , Rongen G. A. , Smits P. , Hopman M. T. E.
Published: October 2007

The inner surrounding of arterial vessels, the endothelium, is optimally located to detect changes in blood characteristics or blood flow that may result from changes in physical activity or from diseases. In response to physical stimuli, the endothelium varies its release of circulating vasoactive substances and serves as a source of local and systemic endothelium‐derived dilator and vasoconstrictor factors. Endothelial dysfunction is one of the earliest markers of vascular abnormalities observed in cardiovascular disease and ageing. Exercise training is an efficient therapeutic strategy to improve endothelial function. Traditionally, studies on endothelial dysfunction and physical (in)activity‐related effects on vascular adaptations are primarily focused on vasodilator substances (i.e. nitric oxide). One may suggest that augmentation of vasoconstrictor pathways (such as endothelin‐1 and angiotensin II) contributes to the endothelial dysfunction observed after physical inactivity. Moreover, these pathways may also explain the exercise‐induced beneficial cardiovascular adaptations. This review summarizes the current knowledge on the effects of physical (in)activity on several endothelium‐derived vasoconstrictor substances.
Beam Forming of Lamb Waves for Structural Health Monitoring
Authors: Olson Steven E. , DeSimio Martin P. , Derriso Mark M.
Published: October 2007

Structural health monitoring techniques are being developed to reduce operations and support costs, increase availability, and maintain safety of current and future air vehicle systems. The use of Lamb waves, guided elastic waves in a plate, has shown promise in detecting localized damage, such as cracking or corrosion, due to the short wavelengths of the propagating waves. Lamb wave techniques have been utilized for structural health monitoring of simple plate and shell structures. However, most aerospace structures are significantly more complex and advanced techniques may be required. One advanced technique involves using an array of piezoelectric transducers to generate or sense elastic waves in the structure under inspection. By adjusting the spacing and/or phasing between the piezoelectric transducers, transmitted or received waves can be focused in a specific direction. This paper presents beam forming details based on analytical modeling, using the finite element method, and experimental testing, using an array of piezoelectric transducers on an aluminum panel. Results are shown to compare well to theoretical predictions.
An Optimal Sensitivity-Enhancing Feedback Control Approach via Eigenstructure Assignment for Structural Damage Identification
Authors: Jiang L. J. , Tang J. , Wang K. W.
Published: October 2007

The concept of using sensitivity-enhancing feedback control to improve the performance of frequency-shift-based structural damage identification has been recently explored. In previous studies, however, the feedback controller is designed to alter only the closed-loop eigenvalues, and the effect of closed-loop eigenvectors on the sensitivity enhancement performance has not been considered. In this research, it is shown that the sensitivity of the natural frequency shift to the damage in a multi-degree-of-freedom structure can be significantly influenced by the placement of both the eigenvalues and the eigenvectors. A constrained optimization problem is formulated to find the optimal assignment of both the closed-loop eigenvalues and eigenvectors, and then an optimal sensitivity-enhancing control is designed to achieve the desired closed-loop eigenstructure. Another advantage of this scheme is that the dataset of frequency measurement for damage identification can be enlarged by utilizing a series of closed-loop controls, which can be realized by activating different combinations of actuators in the system. Therefore, by using this proposed idea of multiple sensitivity-enhancing feedback controls, we can simultaneously address the two major limitations of frequency-shift-based damage identification: the low sensitivity of frequency shift to damage effects and the deficiency of frequency measurement data. A series of case studies are performed. It is demonstrated that the sensitivity of natural frequency shift to stiffness reduction can be significantly enhanced by using the designed sensitivity-enhancing feedback control, where the optimal placement of closed-loop eigenvectors plays a very important role. It is further verified that such sensitivity enhancement can directly benefit the damage identification accuracy and robustness.
Improving Excitations for Active Sensing in Structural Health Monitoring via Evolutionary Algorithms
Authors: Olson Colin C. , Todd M. D. , Worden Keith , Farrar Charles
Published: October 2007

Active excitation is an emerging area of study within the field of structural health monitoring whereby prescribed inputs are used to excite the structure so that damage-sensitive features may be extracted from the structural response. This work demonstrates that the parameters of a system of ordinary differential equations may be adjusted via an evolutionary algorithm to produce excitations that improve the sensitivity and robustness to extraneous noise of state-space based damage detection features extracted from the structural response to such excitations. A simple computational model is used to show that significant gains in damage detection and quantification may be obtained from the response of a spring-mass system to improved excitations generated by three separate representative ordinary differential equation systems. Observed differences in performance between the excitations produced by the three systems cannot be explained solely by considering the frequency characteristics of the excitations. This work demonstrates that the particular dynamic evolution of the excitation applied to the structure can be as important as the frequency characteristics of said excitation if improved damage detection is desired. In addition, the implied existence of a globally optimum excitation (in the sense of improved damage assessment) for the model system is explored.
Thermokarst Lakes as a Source of Atmospheric CH
4
During the Last Deglaciation
Authors: Walter K. M. , Edwards M. E. , Grosse G. , Zimov S. A. , Chapin F. S.
Published: October 2007

Polar ice-core records suggest that an arctic or boreal source was responsible for more than 30% of the large increase in global atmospheric methane (CH
4
) concentration during deglacial climate warming; however, specific sources of that CH
4
are still debated. Here we present an estimate of past CH
4
flux during deglaciation from bubbling from thermokarst (thaw) lakes. Based on high rates of CH
4
bubbling from contemporary arctic thermokarst lakes, high CH
4
production potentials of organic matter from Pleistocene-aged frozen sediments, and estimates of the changing extent of these deposits as thermokarst lakes developed during deglaciation, we find that CH
4
bubbling from newly forming thermokarst lakes comprised 33 to 87% of the high-latitude increase in atmospheric methane concentration and, in turn, contributed to the climate warming at the Pleistocene-Holocene transition.
Decision Theory: What "Should" the Nervous System Do?
Authors: Körding Konrad
Published: October 2007

The purpose of our nervous system is to allow us to successfully interact with our environment. This normative idea is formalized by decision theory that defines which choices would be most beneficial. We live in an uncertain world, and each decision may have many possible outcomes; choosing the best decision is thus complicated. Bayesian decision theory formalizes these problems in the presence of uncertainty and often provides compact models that predict observed behavior. With its elegant formalization of the problems faced by the nervous system, it promises to become a major inspiration for studies in neuroscience.
The Coevolution of Parochial Altruism and War
Authors: Choi Jung-Kyoo , Bowles Samuel
Published: October 2007

Altruism—benefiting fellow group members at a cost to oneself—and parochialism—hostility toward individuals not of one's own ethnic, racial, or other group—are common human behaviors. The intersection of the two—which we term “parochial altruism”—is puzzling from an evolutionary perspective because altruistic or parochial behavior reduces one's payoffs by comparison to what one would gain by eschewing these behaviors. But parochial altruism could have evolved if parochialism promoted intergroup hostilities and the combination of altruism and parochialism contributed to success in these conflicts. Our game-theoretic analysis and agent-based simulations show that under conditions likely to have been experienced by late Pleistocene and early Holocene humans, neither parochialism nor altruism would have been viable singly, but by promoting group conflict, they could have evolved jointly.
A Bacterial Effector Acts as a Plant Transcription Factor and Induces a Cell Size Regulator
Authors: Kay Sabine , Hahn Simone , Marois Eric , Hause Gerd , Bonas Ulla
Published: October 2007

Pathogenicity of many Gram-negative bacteria relies on the injection of effector proteins by type III secretion into eukaryotic cells, where they modulate host signaling pathways to the pathogen's benefit. One such effector protein injected by
Xanthomonas
into plants is AvrBs3, which localizes to the plant cell nucleus and causes hypertrophy of plant mesophyll cells. We show that AvrBs3 induces the expression of a master regulator of cell size,
upa20
, which encodes a transcription factor containing a basic helix-loop-helix domain. AvrBs3 binds to a conserved element in the
upa20
promoter via its central repeat region and induces gene expression through its activation domain. Thus, AvrBs3 and likely other members of this family provoke developmental reprogramming of host cells by mimicking eukaryotic transcription factors.
A Surface-Tailored, Purely Electronic, Mott Metal-to-Insulator Transition
Authors: Moore R. G. , Zhang Jiandi , Nascimento V. B. , Jin R. , Guo Jiandong , Wang G.T. , Fang Z. , Mandrus D. , Plummer E. W.
Published: October 2007

Mott transitions, which are metal-insulator transitions (MITs) driven by electron-electron interactions, are usually accompanied in bulk by structural phase transitions. In the layered perovskite Ca
1.9
Sr
0.1
RuO
4
, such a first-order Mott MIT occurs in the bulk at a temperature of 154 kelvin on cooling. In contrast, at the surface, an unusual inherent Mott MIT is observed at 130 kelvin, also on cooling but without a simultaneous lattice distortion. The broken translational symmetry at the surface causes a compressional stress that results in a 150% increase in the buckling of the Ca/Sr-O surface plane as compared to the bulk. The Ca/Sr ions are pulled toward the bulk, which stabilizes a phase more amenable to a Mott insulator ground state than does the bulk structure and also energetically prohibits the structural transition that accompanies the bulk MIT.
The Impact of Agricultural Soil Erosion on the Global Carbon Cycle
Authors: Van Oost K. , Quine T. A. , Govers G. , De Gryze S. , Six J. , Harden J. W. , Ritchie J. C. , McCarty G. W. , Heckrath G. , Kosmas C. , Giraldez J. V. , da Silva J. R. Marques , Merckx R.
Published: October 2007

Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year
–1
to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year
–1
resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO
2
.
Mnemonic Function of the Dorsolateral Prefrontal Cortex in Conflict-Induced Behavioral Adjustment
Authors: Mansouri Farshad A. , Buckley Mark J. , Tanaka Keiji
Published: October 2007

Our cognitive abilities in performing tasks are influenced by experienced competition/conflict between behavioral choices. To determine the role of the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) in the conflict detection-resolution process, we conducted complementary lesion and single-cell recording studies in monkeys that were resolving a conflict between two rules. We observed conflict-induced behavioral adjustment that persisted after lesions within the ACC but disappeared after lesions within the DLPFC. In the DLPFC, activity was modulated in some cells by the current conflict level and in other cells by the conflict experienced in the previous trial. These results show that the DLPFC, but not the ACC, is essential for the conflict-induced behavioral adjustment and suggest that encoding and maintenance of information about experienced conflict is mediated by the DLPFC.