Refinement of Twinned Structures with SHELXL97

1998 ◽  
Vol 54 (4) ◽  
pp. 443-449 ◽  
Author(s):  
R. Herbst-Irmer ◽  
G. M. Sheldrick

Four examples of the refinement of twinned structures are discussed. These structures illustrate three different types of twins: twinning by merohedry, pseudo-merohedry and non-merohedral twins. How the twinning was detected, how the structures were solved and how they were refined are shown in this paper. The difference between a refinement as a disordered model and a twinned model is illustrated. Sometimes the twin law was necessary to solve the structure, while in the other examples the twinning was first recognized during refinement of the structures. Finally, a list of `characteristic warning signs' is presented which are indicative of possible twinning.

1917 ◽  
Vol 25 (2) ◽  
pp. 341-347 ◽  
Author(s):  
Tokuzo Ohira ◽  
Hideyo Noguchi

Trichomonades from the mouth were studied by Steinberg who proposed to group them into three distinct types; namely, Trichomonas elongata, Trichomonas caudata, and Trichomonas flagellata. Doflein (3) regards them as probably identical with Trichomonas hominis. Opinions differ as to whether or not Trichomonas vaginalis Donné and Trichomonas hominis Grassi are the same species. Lynch, for instance, believes that they are the same species, while von Prowazek (4), Bensen (5), and others (6, 7) insist that they are different types. Bensen's view seems to be well supported by the difference alleged to be found between the mode of encystment in the two trichomonades, were it not for the fact that our knowledge about the so called cyst of trichomonades is still obscure. According to Alexeieff (8) many of the so called cysts were evidently blastomyces contained in the cell body of the trichomonas. An autogamy alleged to take place in cysts as described by Bohne and von Prowazek (9) has not been confirmed by Dobell (10). And Wenyon (11) contends that it has never been found possible to produce any development of these cysts outside the body on the warm stage as can be done with the cysts of Entamœba coli. Therefore, it is still premature to take the process of encystment into consideration as far as the classification of trichomonas is concerned. On the other hand, Rodenwaldt (12) seems to think that there are many species of trichomonas in the human intestines, and Wenyon has described a new trichomonas from the human intestines (Macrostoma mesnili Wenyon). Further cultural studies in the morphology and biology of these organisms must be carried out in order to solve these problems. In the light of modern investigations there are five subgenera to be included under the genus Trichomonas Donné. They are as follows: (1) Protrichomonas Alexeieff, with three anterior flagella, without an undulating membrane. (2) Trichomastix Biitschli) with three anterior flagella and a trailing flagellum (Schleppgeissel) without an undulating membrane. (3) Trichomonas Donné, with three anterior flagella and an undulating membrane. (4) Macrostoma Alexeieff, Amend, Wenyon (11), with three anterior flagella and an undulating membrane wedged in a deep groove (peristome). (5) Tetratrichomonas Parisi (13), with four anterior flagella and an undulating membrane. As far as our culture trichomonas from the human mouth is concerned, it has been shown that it is not strictly a trichomonas and that it should be classed under the subgenus Tetratrichomonas.


Author(s):  
Sandra Halperin ◽  
Oliver Heath

This chapter deals with the first step of the research process: the formulation of a well-crafted research question. It explains why political research should begin with a research question and how a research question structures the research process. It discusses the difference between a topic or general question, on the one hand, and a focused research question, on the other. It also considers the question of where to find and how to formulate research questions, the various types of questions scholars ask, and the role of the ‘literature review’ as a source and rationale for research questions. Finally, it describes a tool called the ‘research vase’ that provides a visualization of the research process, along with different types of questions: descriptive question, explanatory question, predictive question, prescriptive question and normative question.


1990 ◽  
Vol 238 (1293) ◽  
pp. 331-350 ◽  

Free flying bees were trained to collect a reward of sugar-water from a structured figure, placed at a randomly varying location on a sheet of transparent Perspex, positioned 5 cm above a structured Background. During subsequent tests, done in the absence of a reward, the bees’ landings on the boundaries of the figure, as well as within the figure and outside it, were recorded. The same bees were also tested with the figure placed directly on the background, thus eliminating the difference in height between the figure and the background. The results of both types of tests were then compared to identify and investigate the cues that bees use to detect a structured figure, when presented over a structured background. The structure of both the figure and the background were varied in a series of experiments, training a fresh group of bees in each experiment. A randomly structured figure presented against a randomly structured background cannot be detected by the bees unless it is raised above the background. A height difference of 2 cm is sufficient to elicit a rate of landings on the figure that is significantly higher than the chance level. The detectability of the figure does not depend upon the shape of the figure or on differences in density between the structures of the figure and the background. Thus, in detecting the raised figure, the only cue used by the bees appears to be the apparent motion of the figure relative to the background. The majority of landings on a raised figure occur at its boundaries. This shows that the visual stimulus that is crucial in detecting the figure is the local discontinuity in apparent motion that occurs at the boundary. We refer to this as ‘boundary parallax ’. In a series of experiments that used a striped background and a variety of structured figures, three different types of boundary parallax were offered to the bees. These were: (i) ‘covering parallax’, at a boundary in which stripes on either side of the boundary are parallel to the boundary; (ii) ‘shearing parallax’, in which stripes on either side are perpendicular to the boundary and (iii) ‘orthogonal parallax’, in which the stripes on one side are perpendicular to those on the other side. The bees performed very well at detecting raised boundaries that offered covering or shearing parallax, despite the fact that such boundaries are not readily discernible on the basis of their static geometry. On the other hand, bees performed poorly in detecting raised boundaries that offered orthogonal parallax, despite the fact that such boundaries are geometrically quite vivid to the human eye. We propose two neural models for the detection of boundary parallax that account for the sensitivity of bees to covering and shearing parallax and their insensitivity to orthogonal parallax.


1979 ◽  
Vol 44 (3) ◽  
pp. 379-387 ◽  
Author(s):  
Gail Pflaster

This study was designed to determine the value of using a mirror for speech teaching. Data derived from manner, place, voicing, and blend errors produced by 27 hearing-impaired children while imitating consonant-vowel syllables under three conditions (audition alone, audition plus direct vision, audition plus vision using a mirror) were analyzed to determine whether the use of a mirror enhanced or detracted from the accuracy of their responses relative to the other two conditions; whether different types of errors were made under any of the conditions; and whether error types under each condition were related to age or hearing level. Although more place errors occurred under the auditory condition, the difference between the numbers of errors made under the two auditory-visual conditions was not significant. The use of a mirror neither enhanced nor detracted from the accuracy of responses of subjects in this study. This finding cast doubt upon the value of using a mirror as a general aid in speech teaching.


Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1546
Author(s):  
Tomoko Hasegawa ◽  
Nobuyuki Sakai

In Japan, as in other countries, the externalization of food preparation is increasing. Japanese people are interested in the combination of food and tableware and they are concerned about transferring ready-made meals from plastic containers to natural tableware. This study aimed to examine the varying evaluations of meals due to differences in tableware. In this study, we investigated the effect of tableware on meal satisfaction, which is emphasized in Japanese culture. We studied the difference in the evaluation of ready-made meals (a rice ball, salad, croquette, and corn soup) before, during, and after a meal under two conditions: plastic tableware and natural wooden tableware. The results showed that there was no difference in the perceptual evaluation of taste and texture during the meal, except for the color of the salad and the temperature of the soup. On the other hand, meals served on natural wooden tableware were rated more positively than those served on plastic tableware before and after meals. These results suggest that, in Japan, the use of tableware, even for ready-made meals, increases the level of meal satisfaction. These findings have implications for both the providers and consumers of ready-made meals as well as the food industry.


2018 ◽  
Vol 7 (12) ◽  
pp. 480 ◽  
Author(s):  
Taras Agryzkov ◽  
Francisco Pedroche ◽  
Leandro Tortosa ◽  
José Vicent

Identifying the influential nodes in complex networks is a fundamental and practical topic at the moment. In this paper, a new centrality measure for complex networks is proposed based on two contrasting models that have their common origin in the well-known PageRank centrality. On the one hand, the essence of the model proposed is taken from the Adapted PageRank Algorithm (APA) centrality, whose main characteristic is that constitutes a measure to establish a ranking of nodes considering the importance of some dataset associated to the network. On the other hand, a technique known as two-layers PageRank approach is applied to this model. This technique focuses on the idea that the PageRank centrality can be understood as a two-layer network, the topological and teleportation layers, respectively. The main point of the proposed centrality is that it combines the APA centrality with the idea of two-layers; however, the difference now is that the teleportation layer is replaced by a layer that collects the data present in the network. This combination gives rise to a new algorithm for ranking the nodes according to their importance. Subsequently, the coherence of the new measure is demonstrated by calculating the correlation and the quantitative differences of both centralities (APA and the new centrality). A detailed study of the differences of both centralities, taking different types of networks, is performed. A real urban network with data randomly generated is evaluated as well as the well-known Zachary’s karate club network. Some numerical results are carried out by varying the values of the α parameter—known as dumping factor in PageRank model—that varies the importance given to the two layers (topology and data) within the computation of the new centrality. The proposed algorithm takes the best characteristics of the models on which it is based: on the one hand, it is a measure of centrality, in complex networks with data, whose calculation is stable numerically and, on the other hand, it is able to separate the topological properties of the network and the influence of the data.


1973 ◽  
Vol 29 (02) ◽  
pp. 490-498 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Itsuro Kobayashi ◽  
Tadahiro Sano ◽  
Takio Shimamoto

SummaryThe authors previously reported a transient decrease in adhesive platelet count and an enhancement of blood coagulability after administration of a small amount of adrenaline (0.1-1 µg per Kg, i. v.) in man and rabbit. In such circumstances, the sensitivity of platelets to aggregation induced by ADP was studied by an optical density method. Five minutes after i. v. injection of 1 µg per Kg of adrenaline in 10 rabbits, intensity of platelet aggregation increased to 115.1 ± 4.9% (mean ± S. E.) by 10∼5 molar, 121.8 ± 7.8% by 3 × 10-6 molar and 129.4 ± 12.8% of the value before the injection by 10”6 molar ADP. The difference was statistically significant (P<0.01-0.05). The above change was not observed in each group of rabbits injected with saline, 1 µg per Kg of 1-noradrenaline or 0.1 and 10 µg per Kg of adrenaline. Also, it was prevented by oral administration of 10 mg per Kg of phenoxybenzamine or propranolol or aspirin or pyridinolcarbamate 3 hours before the challenge. On the other hand, the enhancement of ADP-induced platelet aggregation was not observed in vitro, when 10-5 or 3 × 10-6 molar and 129.4 ± 12.8% of the value before 10∼6 molar ADP was added to citrated platelet rich plasma (CPRP) of rabbit after incubation at 37°C for 30 second with 0.01, 0.1, 1, 10 or 100 µg per ml of adrenaline or noradrenaline. These results suggest an important interaction between endothelial surface and platelets in connection with the enhancement of ADP-induced platelet aggregation by adrenaline in vivo.


Author(s):  
Philip Isett

This chapter presents the equations and calculations for energy approximation. It establishes the estimates (261) and (262) of the Main Lemma (10.1) for continuous solutions; these estimates state that we are able to accurately prescribe the energy that the correction adds to the solution, as well as bound the difference between the time derivatives of these two quantities. The chapter also introduces the proposition for prescribing energy, followed by the relevant computations. Each integral contributing to the other term can be estimated. Another proposition for estimating control over the rate of energy variation is given. Finally, the coarse scale material derivative is considered.


Metahumaniora ◽  
2017 ◽  
Vol 7 (3) ◽  
pp. 378
Author(s):  
Vincentia Tri Handayani

AbstrakFolklor yang menghasilkan tradisi lisan merupakan perwujudan budaya yang lahirdari pengalaman kelompok masyarakat. Salah satu bentuk tradisi lisan adalah ungkapan yangmengandung unsur budaya lokal dalam konstruksinya yang tidak dimiliki budaya lainnya.Ungkapan idiomatis memberikan warna pada bahasa melalui penggambaran mental. Dalambahasa Perancis, ungkapan dapat berupa locution dan expression. Perbedaan motif acuansuatu ungkapan dapat terlihat dari pengaruh budaya masyarakat pengguna bahasa. Sebuahleksem tidak selalu didefinisikan melalui unsur minimal, tidak juga melalui kata-kata,baik kata dasar atau kata kompleks, namun dapat melalui kata-kata beku yang maknanyatetap. Hubungan analogis dari makna tambahan yang ada pada suatu leksem muncul dariidentifikasi semem yang sama. Semem tersebut mengarah pada term yang diasosiasikan danyang diperkaya melalui konteks (dalam ungkapan berhubungan dengan konteks budaya).Kata kunci: folklor, ungkapan, struktur, makna idiomatis, kebudayaanAbstractFolklore which produces the oral tradition is a cultural manifestation born out theexperience of community groups. One form of the oral tradition is a phrase that containsthe elements of local culture in its construction that is not owned the other culture. Theidiomatic phrase gives the color to the language through the mental representation. InFrench, the expression can consist of locution and expression. The difference motivesreference of an expression can be seen from the influence of the cultural community thelanguage users. A lexeme is not always defined through a minimal element, nor throughwords, either basic or complex words, but can be through the frost words whose meaningsare fixed. The analogical connection of the additional meanings is on a lexeme arises fromthe identification of the same meaning. The meaning ‘semem’ leads to the associated termsand which are enriched through the context (in idiom related to the cultural context).Keywords : folklore, idioms, structure, idiom meaning, cultureI PENDAHULUAN


Author(s):  
Michel Meyer

Rhetoric has always been torn between the rhetoric of figures and the rhetoric of conflicts or arguments, as if rhetoric were exclusively one or the other. This is a false dilemma. Both types of rhetoric hinge on the same structure. A common formula is provided in Chapter 3 which unifies rhetoric stricto sensu and rhetoric as argumentation as two distinct but related strategies adopted according to the level of problematicity of the questions at stake, thereby giving unity to the field called “Rhetoric.” Highly problematic questions require arguments to justify their answers; non-divisive ones can be treated rhetorically through their answers as if they were self-evident. Another classic problem is how to understand the difference between logic and rhetoric. The difference between the two is due to the presence of questions explicitly answered in the premises in logic and only suggested (or remaining indeterminate) in rhetoric.


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