In this study, human stress responses were compared in experimental office settings with and without wood. The hypothesis was that the office setting with wood furniture would reduce stress responses and improve stress recovery as indicated by salivary cortisol concentration. The within-subjects experiment revealed that overall stress levels were lower in the office-like environment with oak wood than the control room, but there was no detectable difference in stress levels between the office-like environment with walnut wood and the control room. Stress recovery was not found to differ between either environment, possibly because duration of the experiment was too short or that not enough samples were taken during the recovery period.
COBISS.SI-ID: 1541496772
Pleating is an optimal way to increase bendability of wood used in diverse industrial applications. It results in the excessive buckling of cell walls and modifications of constitutive polymers. However, thoughtful understanding of the physical–chemical mechanisms of that modification process is very limited. The main purpose of the present study was to identify changes in functional groups of wood polymers induced by longitudinal compression. Four types of wood samples prepared from beech and sessile oak (untreated, steamed, longitudinally compressed and fixated for 1 min as well as longitudinally compressed and fixated for 18 h) were assessed by infrared spectroscopy. Detailed interpretation of infrared spectra allows identification of changes in the hygroscopicity of wood as well as alterations in the linkage between structural elements in the polymer matrix of wood induced by the applied treatments.
COBISS.SI-ID: 17451011
The design of plateaued functions over GF(2)^n , also known as 3-valued Walsh spectra functions, has been commonly approached by specifying a suitable algebraic normal form which then induces this particular Walsh spectral characterization. In this paper, we consider the reversed design method which specifies these functions in the spectral domain by specifying a suitable allocation of the nonzero spectral values and their signs. We analyze the properties of trivial and nontrivial plateaued functions (as affine inequivalent distinct subclasses), which are distinguished by their Walsh support S_f (the subset of GF(2)^n having the nonzero spectral values) in terms of whether it is an affine subspace or not. The former class exactly corresponds to partially bent functions and admits linear structures, whereas the latter class may contain functions without linear structures. Furthermore, we solve the problem of specifying disjoint spectra (non)trivial plateaued functions of maximal cardinality whose concatenation can be used to construct bent functions in a generic manner. An additional method of specifying affine inequivalent plateaued functions, obtained by applying a nonlinear transform to their input domain, is also given.
COBISS.SI-ID: 13502211
We present an isogeometric framework based on collocation to construct a C^2-smooth approximation of the solution of the Poisson’s equation over planar bilinearly parameterized multi-patch domains. The construction of the used globally C^2-smooth discretization space for the partial differential equation is simple and works uniformly for all possible multi-patch configurations. The basis of the C^2-smooth space can be described as the span of three different types of locally supported functions corresponding to the single patches, edges and vertices of the multi-patch domain. For the selection of the collocation points, which is important for the stability and convergence of the collocation problem, two different choices are numerically investigated. The first approach employs the tensor-product Greville abscissae as collocation points, and shows for the multipatch case the same convergence behavior as for the one-patch case, which is suboptimal in particular for odd spline degree. The second approach generalizes the concept of superconvergent points from the one-patch case to the multi-patch case.
COBISS.SI-ID: 1541882564
A non-trivial automorphism g of a graph ? is called semiregular if the only power g^i fixing a vertex is the identity mapping, and it is called quasi-semiregular if it fixes one vertex and the only power g^i fixing another vertex is the identity mapping. In this paper, we prove that K_4, the Petersen graph and the Coxeter graph are the only connected cubic arc-transitive graphs admitting a quasi-semiregular automorphism, and K_5 is the only connected tetravalent 2-arc-transitive graph admitting a quasi-semiregular automorphism. It will also be shown that every connected tetravalent G-arc-transitive graph, where G is a solvable group containing a quasi-semiregular automorphism, is a normal Cayley graph of an abelian group of odd order.
COBISS.SI-ID: 1541113028