Single element optical systems are nowadays used very seldom due their limited optical properties. Possible solution can be the use of the variable optical components. Without need of movable mechanical parts and currently keeping small dimensions it’s possible to get optical systems with variable focal length in wide range with just one optical element. In this article there are described at this time the most often used designs of these lenses. Furthermore there is also a theoretical optical analysis for selected focal lengths of Varioptic Arctic 314 and Varioptic 416 liquid lenses included. and Jednoprvkové optické systémy jsou v současné době používány velice zřídka, a to z důvodu jejich omezených optických vlastností. Jedno z možných řešení tohoto problému může být použití optických prvků s proměnnými optickými vlastnostmi. Tyto nám umožní konstrukci optických systémů s proměnnou ohniskovou vzdáleností v širokém rozsahu bez potřeby užití pohyblivých prvků a při zachování kompaktních rozměrů. V článku jsou popsány v současné době nejvíce používaná konstrukční řešení těchto čoček. Dále je také provedena analýza vybraných optických vlastností kapalinových čoček Varioptic Arctic 314 a Varioptic Arctic 416 pro některé hodnoty z výrobcem udávaného rozsahu ohniskových vzdáleností.
Let ${\mathcal{M}}_g$ be the moduli space of smooth complex projective curves of genus $g$. Here we prove that the subset of ${\mathcal{M}}_g$ formed by all curves for which some Brill-Noether locus has dimension larger than the expected one has codimension at least two in ${\mathcal{M}}_g$. As an application we show that if $X \in {\mathcal{M}}_g$ is defined over ${\mathbb {R}}$, then there exists a low degree pencil $u\: X \rightarrow {\mathbb {P}}^1$ defined over ${\mathbb {R}}$.
The processing of species-specific communication signals in the auditory system represents an important aspect of animal behavior and is crucial for its social interactions, reproduction, and survival. In this article the neuronal mechanisms underlying the processing of communication signals in the higher centers of the auditory system - inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC) - are reviewed, with particular attention to the guinea pig. The selectivity of neuronal responses for individual calls in these auditory centers in the guinea pig is usually low - most neurons respond to calls as well as to artificial sounds; the coding of complex sounds in the central auditory nuclei is apparently based on the representation of temporal and spectral features of acoustical stimuli in neural networks. Neuronal response patterns in the IC reliably match the sound envelope for calls characterized by one or more short impulses, but do not exactly fit the envelope for long calls. Also, the main spectral peaks are represented by neuronal firing rates in the IC. In comparison to the IC, response patterns in the MGB and AC demonstrate a less precise representation of the sound envelope, especially in the case of longer calls. The spectral representation is worse in the case of low-frequency calls, but not in the case of broad-band ca lls. The emotional content of the call may influence neuronal responses in the auditory pathway, which can be demonstrated by stimulation with time-reversed calls or by measurements performed under different levels of anesthesia. The investigation of the principles of the neural coding of species-specific vocalizations offers some keys for understanding the neural mechanisms underlying human speech perception., D. Šuta, J. Popelář, J. Syka., and Obsahuje bibliografii a bibliografické odkazy
The objective of this paper is to obtain sharp upper bound for the function f for the second Hankel determinant |a2a4 − a 2 3 |, when it belongs to the class of functions whose derivative has a positive real part of order α (0 ≤ α < 1), denoted by RT (α). Further, an upper bound for the inverse function of f for the nonlinear functional (also called the second Hankel functional), denoted by |t2t4 − t 2 3 |, was determined when it belongs to the same class of functions, using Toeplitz determinants.
The spaces of entire functions represented by Dirichlet series have been studied by Hussein and Kamthan and others. In the present paper we consider the space X of all entire functions defined by vector-valued Dirichlet series and study the properties of a sequence space which is defined using the type of an entire function represented by vectorvalued Dirichlet series. The main result concerns with obtaining the nature of the dual space of this sequence space and coefficient multipliers for some classes of vector-valued Dirichlet series.
This study aimed at investigating the protective role of CoQ10
against cadmium (Cd)-induced reproductive toxicity in male rats.
Adult male Wistar rats were exposed to an acute dose of Cd
(25 mg/kg bwt; Cd group), Cd+CoQ10 (25 mg/kg bwt Cd+10 mg
CoQ10; Cd-Q10 group) and distilled water (control) in vivo for
15 consecutive days and semen quality was assessed.
A significant reduction was noted in sperm concentration,
progressive motility, morphology and DNA integrity in both Cdand Cd-Q10 groups in comparison to control indicating
Cd-induced testicular lipid per oxidation (LPO) and decline in
indigenous antioxidant defense system as measured by total
antioxidant capacity (TAC) (p<0.05). However, simultaneous
co-administration of CoQ10 along with Cd (Cd-Q10 group) was
able to improve sperm concentration, motility, progressive
motility, morphology, DNA integrity, and testicular TAC as well as
lower LPO compared to Cd group (p<0.05). Results indicate that
used dose of CoQ10 is capable of moderately ameliorating
reproductive toxicity of Cd by improving semen quality and
reducing testicular oxidative stress.
A class of degree four differential systems that have an invariant conic $ x^2+Cy^2=1$, $C\in {\mathbb{R}}$, is examined. We show the coexistence of small amplitude limit cycles, large amplitude limit cycles, and invariant algebraic curves under perturbations of the coefficients of the systems.
In what way do gender-specific interventions aimed at marginalised men reproduce and transform masculinities, and what kind of masculinity do social professionals, who carry out these projects, work with? This paper analyses how visual materials, spaces and artefacts enable professionals to deal with masculinity and gender-equality issues when working with men whom they assume hold traditional views on masculinity and gender roles. A three-year study of semi-public interventions that worked on individual empowerment, participation and gender equality with marginalised men in the Netherlands revealed that the professionals found it difficult to raise gender-equality issues. In contrast to the other project goals of individual empowerment and participation, gender-equality issues created a discomfort. The authors also discovered that gender equality in most cases was dealt with in more subtle ways than the issues of individual empowerment and participation. In this context, professionals worked with an ideal version of what the ‘new’ masculinity of the participants would look like, which we labelled ‘pacified masculinity’. The paper empirically shows how social professionals benefit from the use of space, images and artefacts to break down rigid gender roles and potentially enable men to construct other versions of masculine identity. Moreover, we argue that visuals and materiality create room for a reflection on the role of men in women’s emancipation., Iris van Huis, Marleen van der Haar., and Obsahuje bibliografii