179,080 research outputs found
An efficient Q-tensor-based algorithm for liquid crystal alignment away from defects
No full textWe develop a fast and accurate approximation of the normally stiff equations which minimize the Landau–de Gennes free energy of a nematic liquid crystal. The resulting equations are suitable for all configurations in which defects are not present, making them ideal for device simulation. Specifically they offer an increase in computational efficiency by a factor of 100 while maintaining an error of order (10-4) when compared to the full stiff equations. As this approximation is based on a Q-tensor formalism, the sign reversal symmetry of the liquid crystal is respected. In this paper we derive these equations for a simple two-dimensional case, where the director is restricted to a plane, and also for the full three-dimensional case. An approximation of the error in the perturbation scheme is derived in terms of the first order correction, and a comparison to the full stiff equations is given
Abstract objects: Species, Kinds, Concepts
No full textIn the paper I present Kotarbiński’s approach to abstract objects and show some mistakes in his investigations. By formal ontology I try to explain Kotarbiński’s view and proffer a new solution, a formal solution that is – I hope – in the spirit of Lvov–Warsaw (Lwów–Warsaw) School
Dataset for: Efficient scattering model of multi-layer systems with anisotropic films
No full textDataset supports: Gill, J. R. E., Perivolari, E., Kaczmarek, M., & D'alessandro, G. (2021). Efficient scattering model of multi-layer systems with anisotropic films. Journal of the Optical Society of America A.
Matlab codes to implement the Iterated Ray Method for an isotropic and an anisotropic stratified optical strucuture.</span
Spectral properties and modes of surface microcavities
No full textThis thesis describes the experimental investigations into the transverse mode structure of nearly hemispherical microcavities. The nearly hemispherical microcavity structures are fabricated electrocemically through a template of self assembled latex spheres. Controlling the electrochemical parameters, such as the electrochemical solution and electrode potential. allows a wide range of nearly hemispherical microcavities to be realised.The spatial intensity profiles arid resonant frequencies of the transverse modes of nearly hemispherical microcavities are measured experimentally for a wide range of cavity lengths amid mirror curvatures. The experimental mode profiles are radially symmetric Gauss-Laguerre modes, but do not display the frequency degeneracies typical of large scale optical cavities. The nearly hemispherical microcavity samples are compared to investigate how the cavity parameters. such as cavity length and mirror curvature, affect the experimental spatial intensity profiles and resonant frequencies of the transverse modes. Higher order modes are observed despite the fact that they are forbidden due to the symmetrical coupling geometry. the symmetry breaking is shown to be produced by the surface roughness of the curved mirror.The frequency degeneracy lifting which occurs in the nearly hemispherical microcavity structures can he explained and modelled by considering non-parabolic elements in the cavity. A number of mathematical models for the cavity propagation are developed based on paraxial theory. these models are analysed and the predictions made from the models are compared with the experimental profiles and frequencies. The basic agreement between theory and experiment shows that the paraxial theory is able to model the cavity modes. However, the spectrum and the mode profiles are quite sensitive functions of the geometry of the cavity amid the surface roughness of the cavity mirrors.The nearly hemispherical microcavities are structures which offer a new fabrication technique allowing inexpensive and a uncomplicated method of fabrication. An important feature of the nearly hemispherical microcavities is the tunability, and the ease in which this can be achieved. The structures are also empty, and this will allow them, in the future, to be easily filled with functional optical materials such as liquid crystals
Ramazzottius oberhaeuseri Kaczmarek 2017, sensu lato
No full text77. Ramazzottius oberhaeuseri (Doyère, 1840) sensu lato [T] MacRobiotus obeRhäuseRi Doy. (Murray 1913) Hypsibius obeRhäseRi Doyère, 1840 (Rahm 1936) Hypsibius obeRhaeuseRi C.G. Ehrenberg, 1848 (Teunissen 1938) Hypsibius obeRhaüseRi (Doyère) 1840 (da Cunha & do Nascimento 1964) H. (H.) obeRhaüseRi (Doyère, 1840) (Séméria 1986) Terra typica: Germany (Europe) Angola: • 14°55′S, 13°30′E; 1,750 m asl: Huíla Province, surroundings of Sá da Bandeira [Lubango], lichens. da Cunha & do Nascimento (1964) Israel and Palestinian National Authority: • 32°41′N, 35°23′E; 550 m asl: Tavor Mountain Reserve, Tabor Mt., extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 32°13′N, 35°16′E; 550 m asl: Judean Mountains, Samaria, Nablus, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 32°05′N, 34°53′E; 50 m asl: Petah Tikva, humid climate, lichen. Rahm (1936) • 31°47′N, 35°13′E; 800 m asl: Judean Mountains, Jerusalem, wall of Abyssinian [Ethiopian] Church, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°47′N, 35°14′E; 750 m asl: Judean Mountains, Jerusalem, City Wall of Jerusalem, Damascus Gate, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°47′N, 35°15′E; 800 m asl: Judean Mountains, Jerusalem, Olives Mt., Pater Noster church, Russians tower, wall of church, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°46′N, 35°14′E; 750 m asl: Judean Mountains, Jerusalem, Zion Mt., wall behind the Church of Zion, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°46′N, 35°16′E; 650 m asl: Judean Mountains, al-Eizariya, Bethany, Tomb of Lazarus, rock, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°41′N, 35°10′E; 800 m asl: Judean Mountains, Solomon's Pools, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°32′N, 35°06′E; 950 m asl: Judean Mountains, Hebron, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) • 31°32′N, 35°06′E; 950 m asl: Judean Mountains, Hebron, Abraham's Oak, extreme arid climate or semi-arid climate, moss (BaRbula sp.?). Rahm (1936) Jordan: • 31°50′N, 36°49′E; 500 m asl: Zarqa Governorate, Zarqa [Azarq Wetland Reserve], moss. Kaczmarek & Michalczyk (2004a) Kenya: • 00°01′S, 37°54′E: Undefined locality, British East Africa [Kenya], moss. Murray (1913) Morocco: • 33°31′N, 05°07′W; 1,650 m asl: Meknès-Tafilalet Region, Ras al Ma [Res el Ma], mosses trees (CedRus) and rocks. Séméria (1986) • 33°27′N, 05°13′W; 1,250 m asl: Meknès-Tafilalet Region, ca. 30 [60] km S of Meknes, Azrou, lichens. Séméria (1986) Republic of South Africa: • 25°45′S, 28°11′E; 1,300 m asl: Gauteng Province, Pretoria, moss. Murray (1913) Rwanda: • 01°30′S, 29°32′E; 2,400 m asl: Northern Province, Albert National Park [Volcanoes National Park], Kibga, S slope of the volcano Visoke, at the edge of a bamboo forest, soil. Teunissen (1938) Uganda: • 01°22′N, 32°17′E: Undefined locality, moss. Murray (1913) Record numbers. Angola: 1; Israel and Palestinian National Authority: 11, Jordan: 1, Republic of South Africa: 1, Rwanda: 1, Kenya: 1, Morocco: 2, Uganda: 1; total: 19. Remarks. Ramazzottius oberhaeuseri is a species complex with a cosmopolitan distribution (McInnes 1994, see also Pilato et al. 2013). Recent papers have begun to identify individual species (see: Degma et al. 2009– 2016), though most require the presence of eggs (see Biserov 1998 for a diagnostic key to the genus). The presence of R. oberhaeuseri in Africa remains unconfirmed. Some North African specimens may belong to the recently described R. libycus (see above) or another Ramazzottius species. Murray (1913), briefly reported specimens from Uganda and Kenya, which he described as, “strongly papillose over the whole body, and brightly coloured, varying from the typical madder brown to vivid purple”. We suggest these specimens do not belong to the nominal R. oberhaeuseri but may represent R. szeptycki.Published as part of Kaczmarek, Łukasz, 2017, Annotated zoogeography of non-marine Tardigrada. Part IV: Africa, pp. 1-74 in Zootaxa 4284 (1) on page 31, DOI: 10.11646/zootaxa.4284.1.1, http://zenodo.org/record/101040
Optimal liquid crystal modulation controlled by surface alignment and anchoring strength
No full textSpatial modulation of liquid crystals can be controlled and adjusted by light polarization, the degree of pretilt on the substrates, anchoring strength, and the experimental geometry. In particular, strong anchoring can affect the liquid crystal orientation in opposite ways, depending on the polarization of the incident light. Here we present a theoretical model that describes the liquid crystal modulation and how it can be controlled and optimized. The model is valid for electric fields with a uniform component that is large with respect to the spatial modulation, a situation typical of spatial light modulators and photorefractive cells
Recommended abbreviations for the names of genera of the phylum Tardigrada
No full textPerry, Emma, Miller, William R., Kaczmarek, Łukasz (2019): Recommended abbreviations for the names of genera of the phylum Tardigrada. Zootaxa 4608 (1): 145-154, DOI: 10.11646/zootaxa.4608.1.
Additional recommended abbreviations for the names of genera of the phylum Tardigrada
No full textPerry, Emma, Miller, William R., Kaczmarek, Łukasz (2021): Additional recommended abbreviations for the names of genera of the phylum Tardigrada. Zootaxa 4981 (2): 398-400, DOI: https://doi.org/10.11646/zootaxa.4981.2.1
Ramazzottius bunikowskae Kaczmarek, Michalczyk & Diduszko, 2006, sp. nov.
No full textRamazzottius bunikowskae sp. nov. (Figs. 1–17) Description Adult (measurements of holotype): Body length 222.0 (Figs. 1–3). Body red due to pigmented transverse bands on dorsal side. Dorsal cuticle with well visible, polygonal tubercles (1.0–3.0 in diameter) clearly larger in posterior part of the body (Figs. 4–5). Tubercles arranged in 8 transverse bands. Granulation on legs absent except for a stripe with small tubercles present on the external parts of legs IV. Eyes absent. Head with two elliptical organs on posterior dorsolateral sides of head (Figs. 6 –7, 8, arrow a). Elliptical organs with some pores (visible in SEM only, Fig. 6). On anterior dorsolateral sides of head two strongly porous areas which could be external parts of chemoreceptors (visible in SEM only) (Figs. 6, 9). Mouth opening anteroventral, surrounded by six somewhat indistinct peribuccal lobes and also six small and sometimes undeveloped peribuccal papillae, placed in between lobes (visible in SEM only) (Fig. 10). Buccopharyngeal apparatus of Ramazzottius type (Fig. 13) with apophyses for insertion of the stylet muscles blunthook shaped, asymmetrical in size and shape, with respect to the frontal plane. Oral cavity armature poorly developed and hardly visible in PCM. Only one band of very small, conical teeth, arranged in 3–5 rows present. Teeth located on ring fold, in posterior oral cavity. Buccal tube 29.5 long (Fig. 13). Buccal tube width: internal 1.0 [3.4], external 2.0 [7.0] with one bend in posterior part of tube (visible only in lateral view). Stylet supports inserted on buccal tube at 16.5 [56.0]. Pharyngeal bulb slightly oval with apophyses and two macroplacoids (Fig. 13). Microplacoid and septula absent. Pharyngeal apophyses very large (almost as large as macroplacoids) and triangular in shape. Macroplacoids slightly oval, without constrictions. First macroplacoid 3.0 [10.2] long. Second macroplacoid shorter, 2.0 [7.0] long. Macroplacoid row 6.0 [20.3] long. Claws of Ramazzottius type, (Figs. 11 –12, 14– 15). Primary branches of external claws long and thin, not connected with secondary branches (Figs. 11–12). Poorly visible lunules on all legs present, better developed on IV pair of legs. Accessory points on primary branches of all external and internal claws present. External (ext) claw of I pair of legs 14.0 [47.0] long, base (bs) of the claw 5.0 [16.9]; II ext (Fig. 11). 16.0 [54.2], bs 6.0 [20.3]; III ext. 16.0 [54.2], bs 6.0 [20.3]; IV ext. 19.0 [64.4], bs 6.0 [20.3], internal 9.0 [30.5]. Bars and other cuticular thickenings on legs absent. Egg: White/colourless, large laid freely (Figs. 16–17). Spherical, with conical processes with very small enlarged, bulbous base. Egg processes situated very close to each other (sometimes in contact). Some processes with bifurcated tips (Fig. 17). Egg processes and surface between processes probably smooth (in LM). Diameter of egg without processes 85.0 and 104.0 including them. Processes 11.0–17.0 high with basal diameter 5.0–7.0. Remarks Results of simple statistical analysis of measurements and pt values of selected morphological structures for eight specimens are given in Table 1. The peribuccal lobes, papillae and porous areas on the head have never been reported in the genus Ramazzottius before, therefore it is not known if these structures are also present in other species of the genus. Processes on eggs seems to be surrounded by rings of small granules but this character should be confirmed based on larger number of eggs because it could be only an artifact. Material examined Twelve specimens and one egg, Russia, Irkutsk Province, northern part of Olhon Island on Lake Baikal, taiga, lichen from stone, near the coast, 05.08.2004; leg. D. Diduszko. Type depositories. Holotype and 8 paratypes (7 adults and 1 egg) are deposited in the Natural History Collections, Faculty of Biology, A. Mickiewicz University, Umultowska 89, 61– 614 oznań, Poland. Etymology The first author takes great pleasure in dedicating the new species to a beautiful, incredible and close to him woman, Anna Bunikowska. Differential diagnosis Ramazzottius bunikowskae sp. nov. is similar to R. caucasicus Biserov, 1998 and R. tribulosus Bertolani & Rebecchi, 1988 in regard to the shape of egg processes. The new species differs from R. caucasicus by: 1. the presence of sculpture on the dorsal side of the body and by very densely arranged egg processes (in R. caucasicus the processes are more spaced). 2. shorter external claws (19.0–32.0 in R. caucasicus and 18.0–20.0 in the new species). 3. different colour of the body (brown in R. caucasicus and red in the new species). 4. larger egg diameter (without processes): 55.0–63.0 in R. caucasicus and 85.0 in the new species. Ramazzottius bunikowskae sp. nov. differs from R. tribulosus by: 1. longer (7.7–9.6 in R. tribulosus and 11.0–17.0 in the new species) and wider base of the egg processes (3.9–4.2 in R. tribulosus and 5.0.0–7.0 in the new species). 2. very densely arranged egg processes (in R. tribulosus the processes are more spaced). 3. bulbous base and conical apices of egg processes (processes conical without bulbous base in R. tribulosus). 4. larger egg diameter (without processes): 53.8 –59.0 in R. tribulosus and 85.0 in the new species. 5. shorter claws: a) leg I external/internal (18.5 / 11.1 in R. tribulosus (specimen 287.1 long) and 14.5 /9.0 in the new species (specimen 285.0 long)); b) leg II internal (11.4 in R. tribulosus (specimen 287.1 long) and 9.0 in the new species (specimen 285.0 long)); c) leg IV external/internal (22.8 / 12.9 in R. tribulosus (specimen 287.1 long) and 20 / 10.0 in the new species (specimen 285.0 long)).Published as part of Kaczmarek, Łukasz, Michalczyk, Łukasz & Diduszko, Dawid, 2006, Ramazzottius bunikowskae, a new species of Tardigrada (Eutardigrada, Hypsibiidae) from Russia, pp. 49-57 in Zootaxa 1229 on pages 50-56, DOI: 10.5281/zenodo.27343
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