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The structural, magnetic, and dielectric properties of ceramic samples of Yb-doped PbFe2/3W1/3O3 have been investigated by a variety of methods including x-ray powder diffraction, magnetometry, and dielectric spectroscopy. In addition, theoretical investigations were made using first-principles density functional calculations. All the doped samples Pb(Fe1 − xYbx)2/3W1/3O3 (PFYWO) (0.1 ≤ x ≤ 0.5) were found to crystallize in an ordered cubic (F m 3 ¯ m) structure with partial ordering in the B-perovskite sites. Observed changes in the cationic order were accompanied by differences in the dielectric and magnetic responses of the system. While pure PbFe2/3W1/3O3 is antiferromagnetic, the doped Pb(Fe1 − xYbx)2/3W1/3O3 PFYWO samples display excess moments and ferrimagnetic-like behavior, associated with differences in B′ and B″ site occupancies of the magnetic Fe3+ cations. The magnetic transition temperature of the ferrimagnetic phase is found to decrease with increasing Yb content, from TN ∼350 K of the undoped sample down to 137 K for x = 0.5. All PFYWO compounds display a ferroelectric relaxor behavior akin to that of PbFe2/3W1/3O3, albeit our results show significant changes of the frequency and temperature dependence of the dielectric properties. The changes of the properties of PFYWO with increasing Yb substitution can be explained by the changes in the cation size/charge mismatch and the size difference of the two ordered positions. [ABSTRACT FROM AUTHOR]

A high-throughput and data-mining search for rare-earth-free permanent magnets is reported for materials containing a 3d and p-element of the Periodic Table. Three of the most promising compounds, Fe 2 C, Mn 2 MoB 4 , and Mn 2 WB 4 , were investigated in detail by ab initio electronic structure theory coupled to atomistic spin-dynamics. For these systems doping protocols were also investigated and, in particular, (Fe 0.75 X 0.25 ) 2 C (X = Mn, Cr, V, and Ti), Mn 2 XB 4 (X = Mo and W) along with Mn 2 (X 0.5 Y 0.5 )B 4 (X,Y = Mo, W, Ta, Cr) are suggested here as promising candidates for applications as permanent magnets. Several promising high-performance rare-earth-free permanent magnets have been found as a result of an ab initio high-throughput search. Alteration proposed to improve their stability and magnetic properties. [ABSTRACT FROM AUTHOR]

Increased soluble levels of complement effectors have been demonstrated in active anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), but the timing of complement activation in the autoimmune inflammation remains elusive. This study investigated whether the complement system is activated before onset of symptoms in AAV. The Swedish National Patient Register and Cause of Death register were linked to registers of five biobanks to identify individuals sampled before AAV symptom onset. Diagnosis of AAV and time-point for symptom onset were confirmed by reviewing medical records. We identified 64 presymptomatic individuals with serum samples > 1 month < 10 years from AAV symptom onset and 122 matched controls. Complement factors (C2, C5) and activation markers (C5a, C4b) were measured using Luminex technology. Presymptomatic individuals had higher levels of C5 up to 6.5 years before symptom onset, compared with controls [median (IQR) 80.7 (131.9) vs 46.6 (63.4) µg/mL, p = 0.05]. Levels of C5a increased significantly during the pre-dating time (p = 0.033) until symptom onset. The complement levels were significantly higher in presymptomatic myeloperoxidase (MPO)-ANCA+ individuals versus MPO-ANCA− and proteinase-3-ANCA+ individuals. C5 was significantly increased in cases with renal involvement at diagnosis versus controls (p = 0.022), whereas levels of both C5 and C5a were significantly increased in presymptomatic individuals diagnosed with microscopic polyangiitis after onset compared with controls (C5: p = 0.027; C5a: p = 0.027). Activation of the complement system is an early event in the pathogenesis of AAV and is mainly associated with MPO-ANCA+ AAV and with microscopic polyangiitis. [ABSTRACT FROM AUTHOR]

We present an efficient computational approach to evaluate field-dependent entropy of magnetocaloric materials from ab-initio methods. The temperature dependence is reported for the entropy change, specific heat and magnetization for hcp Gd. To obtain optimal accuracy in the calculations, a mixed-scheme for magnetic Monte Carlo simulations is proposed and found to be superior to using pure quantum or classic statistics. It is demonstrated that lattice and magnetic contributions play a role in the entropy change and that the dominating contribution comes from the magnetic contribution. The total calculated entropy change agrees with measurements at room temperature. Demonstration of the accuracy of ab-initio theory, coupled to statistical methods, for accurate calculations of the total entropy variation associated with the magnetic transition of Gd. Reproduction of experimental data of entropy change. [ABSTRACT FROM AUTHOR]

Semiconducting nanocrystals (NCs) have become one of the leading materials in a variety of applications, mainly due to their size tunable band gap and high intensity emission. Their photoluminescence (PL) properties can be notably improved by capping the nanocrystals with a shell of another semiconductor, making core-shell structures. We focus our study on the CdS/ZnS core-shell nanocrystals that are closely related to extensively studied CdSe/CdS NCs, albeit exhibiting rather different photoluminescence properties. We employ density functional theory to investigate the changes in the electronic and optical properties of these nanocrystals with size, core/shell ratio, and interface structure between the core and the shell. We have found that both the lowest unoccupied eigenstate (LUES) and the highest occupied eigenstate (HOES) wavefunction (WF) are localized in the core of the NCs, with the distribution of the LUES WF being more sensitive to the size and the core/shell ratio. We show that the radiative lifetimes are increasing, and the Coulomb interaction energies decrease with increasing NC size. Furthermore, we investigated the electronic and optical properties of the NCs with different interfaces between the core and the shell and different core types. We find that the different interfaces and core types have rather small influence on the band gaps and the absorption indexes, as well as on the confinement of the HOES and LUES WFs. Also the radiative lifetimes are found to be only slightly influenced by the different structural models. In addition, we compare these results with the previous results for CdSe/CdS NCs, reflecting the different PL properties of these two types of NCs. We argue that the difference in their Coulomb interaction energies is one of the main reasons for their distinct PL properties. [ABSTRACT FROM AUTHOR]

Using Near Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy, the thickness dependent formation of Lutetium Phthalocyanine (LuPc2) films on a stepped passivated Si(100)2×1 reconstructed surface was studied. Density functional theory (DFT) calculations were employed to gain detailed insights into the electronic structure. Photoelectron spectroscopy measurements have not revealed any noticeable interaction of LuPc2 with the H-passivated Si surface. The presented study can be considered to give a comprehensive description of the LuPc2 molecular electronic structure. The DFT calculations reveal the interaction of the two molecular rings with each other and with the metallic center forming new kinds of orbitals in between the phthalocyanine rings, which allows to better understand the experimentally obtained NEXAFS results. [ABSTRACT FROM AUTHOR]

By means of first principles density functional theory, we investigate the properties of the TiN(001)/fcc Fe(111) and TiN(001)/bcc Fe(110) interfaces. We demonstrate that along certain directions Fe slides with negligible energy barriers against TiN at both interfaces, whereas sliding along other directions is involved with significant energy barriers. The interface between bcc Fe and TiN has a low energy barrier for sliding along the [110] direction of the TiN lattice, as does sliding along the [010] direction at TiN(001)/fcc Fe(111). For fcc Fe on TiN, a large energy barrier is found for sliding along the [100] direction of the TiN lattice. We show that this phenomenon and the stability of these interfaces are determined by the interplay between N-Fe bonding and Ti-Fe antibonding interactions. [ABSTRACT FROM AUTHOR]

We report on first principles calculations that describe the electronic structure, magnetic exchange interactions, and ordering temperatures of diluted magnetic semiconductors. The calculated interatomic exchange couplings are used in a Heisenberg Hamiltonian, and ordering temperatures are calculated with the use of Monte Carlo simulations. The accuracy of the method is analyzed by comparing observed and calculated ordering temperatures of several Mn and Cr doped III-V and II-VI semiconductors. The effect of magnetic percolation is discussed along with clustering phenomena and the effect of strong electron-electron interaction. [ABSTRACT FROM AUTHOR]

We have used the linear muffin-tin-orbital method, without geometrical approximations, to calculate the electronic structure of tetragonal BaTiO and cubic SrTiO. Using our self-consistent potential, we have calculated the frequency-dependent dielectric function and the reflectivity spectrum. For tetragonal BaTiO the anisotropic optical properties are calculated. We compare our calculations with experimental data and find good agreement. We analyze the origin of the different calculated features in the optical spectra by means of our energy-band structure. c 2001 American Institute of Physics. [DOI: 10.1063/1.1384862]. [ABSTRACT FROM AUTHOR]

Half-metallic ferromagnets are promising candidates for use in spintronic devices. In order to investigate the complex magnetism of such systems, we have studied the magnetic interactions in zinc-blende MnX (X=N,P,As,Bi,Sb) systems as a function of volume by ab initio density functional calculations. The calculated Heisenberg pair-exchange parameters show a strong volume dependence resulting in the transition from a metallic to a half-metallic behavior for certain systems. As a result, in MnAs, the calculated Curie temperatures, obtained from Monte Carlo simulations using ab initio exchange parameters and a classical Heisenberg Hamiltonian, increase with an increase in volume. Calculations of self-consistent noncollinear spin configurations indicate that spins deviate strongly from collinear ordering for low volumes whereas they align in a collinear ferromagnetic fashion for high volumes. [ABSTRACT FROM AUTHOR]

We have studied the electronic structure of Co doped ZnO by theory and experiment. Photoelectron and x-ray absorption spectroscopy experiments were performed on 5% Co doped ZnO thin films. The results show that Co-3d states lie in the valence band and hybridize considerably with O-2p states. These results compare qualitatively with our density functional calculations combined with a Hubbard approach to include strong electron correlations within the Co-3d state. [ABSTRACT FROM AUTHOR]

Here, we have studied the chemical and magnetic interactions in Co doped ZnO diluted magnetic semiconductor by ab initio density functional calculations. The calculated chemical pair interaction parameters suggest a strong tendency of clustering between Co atoms. Both chemical and magnetic pair interaction parameters are short ranged with a large first neighbor interaction. Monte Carlo simulations show that the Curie temperature for a homogeneous sample is low, whereas allowing for an inhomogeneous growth results in very high Curie temperatures. It is argued that these inhomogeneities may be the reason for the observation of high Curie temperatures in Co doped ZnO. It is also demonstrated that the electronic structure is modified significantly in presence of Co clusters. [ABSTRACT FROM AUTHOR]

The properties of dilute magnetic semiconductors are usually strongly influenced by the defects present in the system. Ab initio calculations may provide valuable insight for the microscopic understanding of the interactions with defects. Here, we present studies of Mn-doped ZnO in the presence of several defects by a combined approach of ab initio electronic structure calculations using Korringa-Kohn-Rostoker-coherent potential approximation and Monte Carlo simulations (MCSs). Electronic structure and magnetic interactions have similar trends for wurtzite and zinc-blende crystal structures. A weak antiferromagnetic interaction has been found for 5% Mn doping in defect-free ZnO. Defects such as O vacancies and Zn interstitials lead to antiferromagnetic interactions between the Mn atoms, while Zn vacancies and oxygen substitution by nitrogen yield ferromagnetic interactions. As the concentration of Mn is low and the exchange interactions are short ranged, MCSs show small values of Curie temperatures (not more than 50 K). However, for a few cases with codoping of Mn and defects, we obtained higher Curie temperatures (around 130 K). Estimates of the Curie temperatures, assuming an average separation of the Mn atoms in the mean-field solution of Heisenberg model, are in very good agreement with the results obtained from MCS. [ABSTRACT FROM AUTHOR]

We have investigated the phase stability of two MAX phases, V3SiC2 and V2SiC, by means of first-principles total-energy calculations within the generalized-gradient approximation and the projector-augmented wave method. The theoretical bulk modulus of V3SiC2 is 219 GPa, which is ∼17% larger than that of Ti3SiC2 (187 GPa). The total-energy calculations show that V2SiC is stable with a formation energy of about 0.27 eV\f.u. and that V3SiC2 is metastable (only 0.02 eV\f.u. is required to stabilize this phase from its competing phases). We suggest that both these two MAX compounds should be possible to synthesize as stable (or metastable) phases using, e.g., thin-film deposition. [ABSTRACT FROM AUTHOR]

The electronic structure of α, γ, and β phases of MgH2 is studied using the state of the art all-electron projector-augmented-wave GW approximation. Both the ground-state and the high-pressure transformations are considered in this investigation. We have found an indirect (direct) band gap of 5.58 eV (6.52 eV) for α-MgH2 in good agreement with the experimental findings. For the γ and β phases, we have found indirect (direct) band-gap values of 5.24 eV (5.33 eV) and 3.90 eV (4.72 eV), respectively. The optical properties are investigated by means of the complex dielectric function, which is calculated within the framework of a full-potential linearized augmented plane-wave method and corrected by the scissor operation. All phases are found to be color neutral insulators. [ABSTRACT FROM AUTHOR]

Methods for the detection of influenza epidemics and prediction of their progress have seldom been comparatively evaluated using prospective designs. This study aimed to perform a prospective comparative trial of algorithms for the detection and prediction of increased local influenza activity. Data on clinical influenza diagnoses recorded by physicians and syndromic data from a telenursing service were used. Five detection and three prediction algorithms previously evaluated in public health settings were calibrated and then evaluated over 3 years. When applied on diagnostic data, only detection using the Serfling regression method and prediction using the non-adaptive log-linear regression method showed acceptable performances during winter influenza seasons. For the syndromic data, none of the detection algorithms displayed a satisfactory performance, while non-adaptive log-linear regression was the best performing prediction method. We conclude that evidence was found for that available algorithms for influenza detection and prediction display satisfactory performance when applied on local diagnostic data during winter influenza seasons. When applied on local syndromic data, the evaluated algorithms did not display consistent performance. Further evaluations and research on combination of methods of these types in public health information infrastructures for ‘nowcasting’ (integrated detection and prediction) of influenza activity are warranted. [ABSTRACT FROM PUBLISHER]

Mycoheterotrophic plants obtain organic carbon from associated mycorrhizal fungi, fully or partially. Angiosperms with this form of nutrition possess exceptionally small 'dust seeds' which after germination develop 'seedlings' that remain subterranean for several years, fully dependent on fungi for supply of carbon. Mycoheterotrophs which as adults have photosynthesis thus develop from full to partial mycoheterotrophy, or autotrophy, during ontogeny. Mycoheterotrophic plants may represent a gradient of variation in a parasitism-mutualism continuum, both among and within species. Previous studies on plant-fungal associations in mycoheterotrophs have focused on either germination or the adult life stages of the plant. Much less is known about the fungal associations during development of the subterranean seedlings. We investigated germination and seedling development and the diversity of fungi associated with germinating seeds and subterranean seedlings (juveniles) in five Monotropoideae (Ericaceae) species, the full mycoheterotroph Monotropa hypopitys and the putatively partial mycoheterotrophs Pyrola chlorantha, P. rotundifolia, Moneses uniflora and Chimaphila umbellata. Seedlings retrieved from seed sowing experiments in the field were used to examine diversity of fungal associates, using pyrosequencing analysis of ITS2 region for fungal identification. The investigated species varied with regard to germination, seedling development and diversity of associated fungi during juvenile ontogeny. Results suggest that fungal host specificity increases during juvenile ontogeny, most pronounced in the fully mycoheterotrophic species, but a narrowing of fungal associates was found also in two partially mycoheterotrophic species. We suggest that variation in specificity of associated fungi during seedling ontogeny in mycoheterotrophs represents ongoing evolution along a parasitism-mutualism continuum. [ABSTRACT FROM AUTHOR]

Provides information on the use of the full potential linear muffin tin orbital method (FPLMTO) to study the elastic and structural properties of ZnO by means of accurate first-principles total energy calculations. Calculations of five different elastic constants of ZnO; Information on the first principles of Zno; Conclusion reached on the method.

Background: Surgical strategy regarding nerve identification and resection in relation to chronic postoperative pain remains controversial. A central question is whether nerves in the operation field, when identified, should be preserved or resected. In the present study, the hypotheses that the identification and consequent resection of nerves 'at risk' have no influence on postoperative pain has been tested.Methods: A single-centre study was conducted in 525 patients undergoing Lichtenstein hernioplasty. One surgeon (364 operations, Group A) consequently resected nerves 'at risk' for being injured and nine surgeons (161 operations, Group B) adhered to the general routine of nerve preservation. All cases were ambulatory surgery on anaesthetised patients and the groups were similar with regard to age, body mass index (BMI) and preoperative pain. Self-reported pain at 3 months was recorded on a 10-box visual analogue scale (VAS). The identification and resection of nerves were continuously registered. Statistical calculations were performed with Fisher's exact test and ordinal logistic regression.Results: There was no significant difference in the number of identified nerves in the two groups of patients (iliohypogastricus, P = 0.555; ilioinguinalis, P = 0.831; genital branch, P = 0.214). However, the number of resected nerves was significantly higher in Group A for the iliohypogastric nerve, P < 0.001, but not for ilioinguinalis, P = 0.064, and genital branch, P = 0.362. Non-identification of the ilioinguinal nerve correlated to the highest level of self-reported postoperative pain at 3 months. Patients in Group A, who had nerves 'at risk' resected from the operation field, reported significantly less postoperative pain at 3 months, P = 0.007.Conclusion: This register study confirms the importance of nerve identification. Nerve resection strategy with the consequent removal of nerves 'at risk' gives a significantly better outcome in Lichtenstein hernioplasty. [ABSTRACT FROM AUTHOR]

The objective of the rare-earth free permanent magnets (REFREEPM) project is to develop a new generation of high-performance permanent magnets (PMs) without rare earths. Our approach is based on modeling using a combinatorial approach together with micromagnetic modeling and the realization of the modeled systems (I) by using a novel production of high-aspect-ratio (>5) nanostructrures (nanowires, nanorods, and nanoflakes) by exploiting the magnetic shape anisotropy of the constituents that can be produced via chemical nanosynthesis polyol process or electrodeposition, which can be consolidated with novel processes for a new generation of rare-earth free PMs with energy product in the range of 60 kJ/m < (BH)max < 160 kJ/m at room temperature, and (II) by using a high-throughput thin-film synthesis and high-throughput characterization approach to identify promising candidate materials that can be stabilized in a tetragonal or hexagonal structure by epitaxial growth on selected substrates, under various conditions of pressure, stoichiometry, and temperature. In this article, we report the progress so far in selected phases. [ABSTRACT FROM AUTHOR]

The intra-atomic magnetic dipole moment - frequently called z> term - plays an important role in the determination of spin magnetic moments by x-ray absorption spectroscopy for systems with nonspherical spin density distributions. In this work, we present the dipole moment as a sensitive monitor to changes in the electronic structure in the vicinity of a phase transiton. In particular, we studied the dipole moment at the Fe2+ and Fe3+ sites of magnetite as an indicator for the Verwey transition by a combination of x-ray magnetic circular dichroism and density functional theory. Our experimental results prove that there exists a local change in the electronic structure at temperatures above the Verwey transition correlated to the known spin reorientation. Furthermore, it is shown that measurement of the dipole moment is a powerful tool to observe this transition in small magnetite nanoparticles for which it is usually screened by blocking effects in classical magnetometry. [ABSTRACT FROM AUTHOR]

Large seeds contain more stored resources, and seedlings germinating from large seeds generally cope better with environmental stresses such as shading, competition and thick litter layers, than seedlings germinating from small seeds. A pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed (shaded) habitats has been suggested and supported by comparative studies. However, few studies have assessed the intra-specific relationship between seed size and recruitment, comparing plant communities differing in canopy cover. Here, seeds from four plant species commonly occurring in ecotones between open and closed habitats ( Convallaria majalis, Frangula alnus, Prunus padus and Prunus spinosa) were weighed and sown individually (3200 seeds per species) in open and closed-canopy sites, and seedling emergence and survival recorded over 3 years. Our results show a generally positive, albeit weak, relationship between seed size and recruitment. In only one of the species, C. majalis, was there an association between closed canopy habitat and a positive seed size effect on recruitment. We conclude that there is a weak selection gradient favouring larger seeds, but that this selection gradient is not clearly related to habitat. [ABSTRACT FROM AUTHOR]

Using density functional theory formulated within the framework of the exact muffin-tin orbital method, we investigate the elastic properties of the body-centered cubic Fe0.85Ni0.1Mg0.05 alloy in the conditions at the Earth's inner core. We demonstrate that in this system, the chemical stabilization effect of Mg is significantly larger than that of Ni. We show that the elastic properties of Fe0.85Ni0.1Mg0.05 are in good agreement with those of the Earth's inner core, as given by seismic observations. We find that the excellent mechanical properties of Fe0.85Ni0.1Mg0.05 are primarily due to Mg. [ABSTRACT FROM PUBLISHER]

Lattice dynamical methods used to predict phase transformations in crystals typically deal with harmonic phonon spectra and are therefore not applicable in important situations where one of the competing crystal structures is unstable in the harmonic approximation, such as the bcc structure involved in the hcp-to-bcc martensitic phase transformation in Ti, Zr and Hf. Here we present an expression for the free energy that does not suffer from such shortcomings, and we show by self-consistent ab initio lattice dynamical calculations (SCAILD), that the critical temperature for the hcp-to-bcc phase transformation in Ti, Zr and Hf, can be effectively calculated from the free-energy difference between the two phases. This opens up the possibility to study quantitatively, from first-principles theory, temperature-induced phase transitions. [ABSTRACT FROM AUTHOR]

Surgical strategy regarding nerve identification and resection in relation to chronic postoperative pain remains controversial. A central question is whether nerves in the operation field, when identified, should be preserved or resected. In the present study, the hypotheses that the identification and consequent resection of nerves ‘at risk’ have no influence on postoperative pain has been tested. A single-centre study was conducted in 525 patients undergoing Lichtenstein hernioplasty. One surgeon (364 operations, Group A) consequently resected nerves ‘at risk’ for being injured and nine surgeons (161 operations, Group B) adhered to the general routine of nerve preservation. All cases were ambulatory surgery on anaesthetised patients and the groups were similar with regard to age, body mass index (BMI) and preoperative pain. Self-reported pain at 3 months was recorded on a 10-box visual analogue scale (VAS). The identification and resection of nerves were continuously registered. Statistical calculations were performed with Fisher’s exact test and ordinal logistic regression. There was no significant difference in the number of identified nerves in the two groups of patients (iliohypogastricus, P = 0.555; ilioinguinalis, P = 0.831; genital branch, P = 0.214). However, the number of resected nerves was significantly higher in Group A for the iliohypogastric nerve, P < 0.001, but not for ilioinguinalis, P = 0.064, and genital branch, P = 0.362. Non-identification of the ilioinguinal nerve correlated to the highest level of self-reported postoperative pain at 3 months. Patients in Group A, who had nerves ‘at risk’ resected from the operation field, reported significantly less postoperative pain at 3 months, P = 0.007. This register study confirms the importance of nerve identification. Nerve resection strategy with the consequent removal of nerves ‘at risk’ gives a significantly better outcome in Lichtenstein hernioplasty. [ABSTRACT FROM AUTHOR]

We investigate the role of magnetic fluctuations in the spectral properties of paramagnetic γ-Mn. Two methods are employed. The Local Density Approximation plus Dynamical Mean-Field Theory together with the numerically exact quantum Monte-Carlo solver is used as a reference for the spectral properties. Then the same scheme is used with the computationally less demanding perturbative spin-polarized fluctuation-exchange solver in combination with the Disordered Local Moment approach, and photoemission spectra are calculated within the one-step model. It is shown that the formation of local magnetic moments in γ-Mn is very sensitive to the value of Hund’s exchange parameter. Comparison with the experimental photoemission spectra demonstrates that γ-Mn is a strongly correlated system, with the Hubbard band formation, which cannot be described by the perturbative approach. However, minor change of parameters would transform it into a weakly correlated system. [ABSTRACT FROM AUTHOR]

Aim To investigate the effect of temperature, latitude and local environment on the reproductive traits of widespread perennial forest herbs to better understand the potential impacts of rising temperatures on their population dynamics and colonization capacities. Location Six regions along a latitudinal gradient from France to Sweden. Methods Within each region, we collected data from three to five populations of up to six species. For each species, several variables were recorded in each region (temperature, latitude) and population (local abiotic and biotic environmental variables), and seed production and germination were estimated. Resource investment in reproduction (RIR) was quantified as seed number × seed mass, while germinable seed output (GSO) was expressed as seed number × germination percentage. We performed linear regression and mixed effect models to investigate the effects of temperature (growing degree hours), latitude and local abiotic and biotic environment on RIR and GSO. Results Temperature and latitude explained most of the variation in RIR and GSO for early flowering species with a northerly distribution range edge ( Anemone nemorosa, Paris quadrifolia and Oxalis acetosella). Reproduction of the more southerly distributed species ( Brachypodium sylvaticum, Circaea lutetiana and Primula elatior), in contrast, was independent of temperature/latitude. In the late summer species, B. sylvaticum and C. lutetiana, variation in RIR and GSO was best explained by local environmental variables, while none of the investigated variables appeared to be related to reproduction in P. elatior. Main conclusions We showed that reproduction of only two early flowering, northerly distributed species was related to temperature. This suggests that the potential reproductive response of forest herbs to climate warming partly depends on their phenology and distribution, but also that the response is to some extent species dependent. These findings should be taken into account when predictions about future shifts in distribution range are made. [ABSTRACT FROM AUTHOR]

Complex regulatory dynamics is ubiquitous in molecular networks composed of genes and proteins. Recent progress in computational biology and its application to molecular data generate a growing number of complex networks. Yet, it has been difficult to understand the governing principles of these networks beyond graphical analysis or extensive numerical simulations. Here the authors exploit several simplifying biological circumstances which thereby enable to directly detect the underlying dynamical regularities driving periodic oscillations in a dynamical nonlinear computational model of a protein–protein network. System analysis is performed using the cell cycle, a mathematically well-described complex regulatory circuit driven by external signals. By introducing an explicit time delay and using a ‘tearing-and-zooming’ approach the authors reduce the system to a piecewise linear system with two variables that capture the dynamics of this complex network. A key step in the analysis is the identification of functional subsystems by identifying the relations between state-variables within the model. These functional subsystems are referred to as dynamical modules operating as sensitive switches in the original complex model. By using reduced mathematical representations of the subsystems the authors derive explicit conditions on how the cell cycle dynamics depends on system parameters, and can, for the first time, analyse and prove global conditions for system stability. The approach which includes utilising biological simplifying conditions, identification of dynamical modules and mathematical reduction of the model complexity may be applicable to other well-characterised biological regulatory circuits. [Includes supplementary material] [ABSTRACT FROM AUTHOR]

This paper presents a suggested methodology based on virtual reality (VR) technology that enables people with cognitive disabilities to communicate their knowledge and experiences of public transport systems. The users interacted with the VR system by verbally describing their actions to the person controlling the VR system and/or pointing with a laser pointer while seated in front of three screens on which the virtual environment (VE) was projected. A surround sound system was used to add realism. The users were video filmed as they took a virtual bus trip and were then asked to think aloud about their experience while watching the video material. The VR methodology was evaluated on seven people with stroke. Overall, the results suggested that the VR methodology is feasible for people with cognitive disabilities. Despite some initial difficulties, the subjects managed to communicate their intentions, some by combining verbalisations and pointing with the laser pointer in a very efficient manner. They were engaged in the virtual bus trip and made comments on the experience, including comments on emotional aspects. Interestingly, the subjects' verbal descriptions of what they wanted to do revealed in parts aspects of how they reasoned when taking the bus trip. [ABSTRACT FROM AUTHOR]

1. Given the speed and extent of changes in vegetation as a result of human activity, there is a need to investigate ways in which individual species’ impacts on ecosystem processes can be generalized and scaled-up to the community level. 2. We focus on linking community functional parameters (mean of the traits of the plants in the community, weighted using four different methods) with litter chemistry and decomposition, in a chronosequence of currently managed and abandoned semi-natural grasslands in southern Sweden. 3. Changes in plant community composition with age since abandonment were reflected in community functional parameters: as expected, aggregated specific leaf area (SLA) declined, and aggregated leaf dry matter content (LDMC) and leaf carbon : nitrogen ratio (C : N) increased with plot age. 4. Several litter chemistry indices were closely linked with plant traits at the community level; in particular, community aggregated LDMC was correlated with the lignin and fibre content of the community litter. 5. Aggregated LDMC stood out as the trait most closely linked to community litter decomposition. This relationship was consistent across all three incubation periods (by which time up to c. 70% mass loss had occurred) and as strong as that between the best single chemical index of litter quality (lignin : N ratio) and litter mass loss. 6. Mass loss of whole community litter, incubated in its plot of origin, was related to mass loss of the same litter incubated under standard conditions, but not to decomposition of a standard substrate, indicating dominant substrate quality control over decomposition. 7. This study demonstrates the potential of the traits of living plants as a tool to link changes in species composition with ecosystem processes at the community level. [ABSTRACT FROM AUTHOR]