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The Influence of Negative Information on Trust in Virtual TeamsLee, Tiffany T. 28 October 2015 (has links)
Organizational work is characterized by positive as well as often negative work behaviors from employees. The same may be said of work done in virtual teams, where computer-mediated communication among team members can be particularly uncivil and inflammatory (Wilson, Straus, & McEvily, 2006). Accordingly, trust has been theorized as more difficult to develop in these types of teams compared to traditional face to face teams. Using a computer simulation of a collaborative team task, this study examined how individuals in virtual teams integrate conflicting pieces of positive and negative information about a teammate into one overall rating of trust. Data were analyzed from 240 individuals to examine the influence of these behaviors on levels of trust toward a target teammate. Evidence of trust quickly developing and declining, i.e., the dynamic nature of trust, in a virtual team was observed. Secondly, the negativity effect was found, where a negative behavior was given more weight in ratings of trust than a positive behavior. Next, the hierarchically restrictive schema was offered as a plausible explanation for the negativity effect due to creating asymmetrical expectations of subsequent behavior based on an initially observed behavior. Lastly, a significant negativity effect was not found when the two behaviors were performed, one each, by a pair of unrelated persons or by a pair of related persons with entitativity.
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A systems biology approach to multi-scale modelling and analysis of planar cell polarity in Drosophila melanogaster wingGao, Qian January 2013 (has links)
Systems biology aims to describe and understand biology at a global scale where biological systems function as a result of complex mechanisms that happen at several scales. Modelling and simulation are computational tools that are invaluable for description, understanding and prediction these mechanisms in a quantitative and integrative way. Thus multi-scale methods that couple the design, simulation and analysis of models spanning several spatial and temporal scales is becoming a new emerging focus of systems biology. This thesis uses an exemplar – Planar cell polarity (PCP) signalling – to illustrate a generic approach to model biological systems at different spatial scales, using the new concept of Hierarchically Coloured Petri Nets (HCPN). PCP signalling refers to the coordinated polarisation of cells within the plane of various epithelial tissues to generate sub-cellular asymmetry along an axis orthogonal to their apical-basal axes. This polarisation is required for many developmental events in both vertebrates and non-vertebrates. Defects in PCP in vertebrates are responsible for developmental abnormalities in multiple tissues including the neural tube, the kidney and the inner ear. In Drosophila wing, PCP is seen in the parallel orientation of hairs that protrude from each of the approximately 30,000 epithelial cells to robustly point toward the wing tip. This work applies HCPN to model a tissue comprising multiple cells hexagonally packed in a honeycomb formation in order to describe the phenomenon of Planar Cell Polarity (PCP) in Drosophila wing. HCPN facilitate the construction of mathematically tractable, compact and parameterised large-scale models. Different levels of abstraction that can be used in order to simplify such a complex system are first illustrated. The PCP system is first represented at an abstract level without modelling details of the cell. Each cell is then sub-divided into seven virtual compartments with adjacent cells being coupled via the formation of intercellular complexes. A more detailed model is later developed, describing the intra- and inter-cellular signalling mechanisms involved in PCP signalling. The initial model is for a wild-type organism, and then a family of related models, permitting different hypotheses to be explored regarding the mechanisms underlying PCP, are constructed. Among them, the largest model consists of 800 cells which when unfolded yields 164,000 places (each of which is described by an ordinary differential equation). This thesis illustrates the power and validity of the approach by showing how the models can be easily adapted to describe well-documented genetic mutations in the Drosophila wing using the proposed approach including clustering and model checking over time series of primary and secondary data, which can be employed to analyse and check such multi-scale models similar to the case of PCP. The HCPN models support the interpretation of biological observations reported in literature and are able to make sensible predictions. As HCPN model multi-scale systems in a compact, parameterised and scalable way, this modelling approach can be applied to other large-scale or multi-scale systems.
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Preparação de zeólitas mordenita com estrutura hierárquica de porosGrecco, Saulo de Tarso Figueiredo 08 1900 (has links)
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Tese_Doutorado_Saulo.pdf: 12043320 bytes, checksum: 9e747c238576b9219840bfcd38f02a2e (MD5) / FINEP, CNPq / As restrições difusionais aos reagentes, causadas pelos microporos, limitam o
uso das zeólitas no processamento de moléculas pesadas. Isto demanda o
desenvolvimento de materiais que combinem as propriedades de zeólitas com as de
materiais mesoporosos. Um número significativo de procedimentos experimentais,
pré ou pós síntese, vem sendo sugerido para a obtenção de zeólitas hierarquicamente
estruturadas. As metodologias de síntese mais bem sucedidas envolvem o uso de
agentes geradores de mesoporosidade (agentes orgânicos e nanopartículas) ou
nanomoldes (moldagem em nanoespaços), que geram sólidos com mesoporosidade
intracristalina com uma estreita distribuição de tamanho de poros; isto resulta em
sólidos contendo mesoporos, além dos microporos intrínsecos das zeólitas. Entretanto,
ainda não existem estudos sistemáticos, que permitam estabelecer o efeito das
variáveis de preparação sobre as características dos sólidos finais. A fim de superar
essa dificuldade, neste trabalho foi estudado o efeito do tempo e da temperatura de
cristalização do gel de síntese sobre as características de materiais baseados em
mordenita com estrutura hierárquica de poros. Na preparação das amostras,
adicionou-se um organossilano gerador de mesoporosidade (TPOAC, cloreto de [3-
(trimetoxissilil)propil]octadecildimetilamônio), ao gel de síntese da mordenita, que foi
cristalizado por diferentes períodos e em distintas temperaturas. Os sólidos obtidos
foram submetidos à troca iônica com cloreto de amônio e posterior calcinação, de
modo a obter a forma ácida do material. As amostras foram caracterizadas por
termogravimetria, espectroscopia no infravermelho com transformada de Fourier,
difração de raios X, análise textural por adsorção de nitrogênio, ressonância
magnética nuclear de 29Si e de 27Al, microscopia eletrônica de varredura e medidas de
acidez por dessorção de amônia à temperatura programada. Observou-se que a
formação da mordenita contendo mesoporos é influenciada pelo tempo e temperatura
de cristalização do gel da zeólita. O emprego de tempos relativamente curtos ou
baixas temperaturas favorece a formação de um sólido amorfo, enquanto longos
tempos ou elevadas temperaturas favorecem a formação de mesoporos intracristalinos
na mordenita. Por outro lado, tempos e temperaturas intermediárias favoreceram a
formação da mordenita com uma estrutura hierárquica de poros e mesoporos
desordenados. O aumento da cristalinidade da mordenita acarreta uma diminuição na
área e no volume de mesoporos, mas promove um acréscimo na área e no volume de
microporos. A área externa também tende a diminuir devido ao aumento do tamanho
do cristal da mordenita em função da cristalinidade. Os sólidos obtidos foram
susceptíveis à desaluminação durante a etapa de calcinação. A extensão da
desaluminação diminuiu com o aumento do tempo ou da temperatura de cristalização,
devido à inserção dos átomos de alumínio na rede da zeólita em formação. Porém, em
tempos de cristalização longos e temperaturas altas, pode ocorrer a redispersão dos
átomos de alumínio. Todos os sólidos apresentaram elevada acidez que aumentou
com a cristalinidade. Entretanto, nas amostras preparadas em tempos curtos e
temperaturas baixas, a maioria dos sítios apresentou força ácida moderada, enquanto
aquelas obtidas em tempos longos e temperaturas altas apresentaram maior
quantidade de sítios ácidos fortes. / The diffusion restrictions of the reactants caused by the micropores limit the
use of zeolites for processing heavy molecules. This demands for the development of
materials that can combine the properties of zeolites and of mesoporous materials. A
significant number of experimental procedures, pre or post synthesis, has been
suggested for obtaining hierarchically structured zeolites. The most successful
synthesis involve the use of mesoporosity generating agents (nanoparticles and
organic agents) or nanotemplates (templating in nanospaces), which generate solids
with intracristaline mesoporosity with a narrow pore size distribution. This results in
solids containing mesoporous besides the intrinsic zeolite micropores. However,
there is not any systematic study which allows to state the effect of crystallization
time and temperature of the synthesis gel on the properties of the final solid. In order
to overcome this difficulty, the effect of time and temperature of the synthesis gel on
the properties of mordenite-based materials with hierarchical pore structure was
studied in this work. In the samples preparation a mesoporosity generating
organosilane (TPOAC, [3-(trimethoxysilyl) propyl] octadecyldimethylammonium
chloride) was added to the synthesis gel of mordenite, which was crystallized for
different times and temperatures. The solids were then submitted to ion exchange
with ammonium chloride and further calcination to obtain the acidic form of the
zeolite. The samples were characterized by thermogravimetry, Fourier transformed
infrared spectroscopy, X-ray diffraction, textural analysis by nitrogen adsorption, 29Si
and 27Al NMR, scanning electron microscopy and acidity measurements by ammonia
desorption. It was observed that the formation of mordenite containing mesoporous is
affected by the time and temperature of crystallization of the zeolite gel. The use of
relatively short times and low temperatures favors the formation of an amorphous
solid, while long times or high temperatures favor the formation of intracristaline
mesoporosity in the mordenite. On the other hand, intermediate times and
temperatures favor the formation of mordenite with hierarchical pore structure and
disordered mesopores. The increase in mordenite crystallinity leads to a decrease in
mesopore area and volume but promotes an increase in micropore area and volume.
The external area also tends to decrease due to the increased crystal size as a function
of mordenite crystallinity. The solids obtained were susceptible to dealumination
during the calcination step. The degree of dealumination decreased with the
increasing crystallization time or temperature due to the insertion of aluminum atoms
in the zeolite lattice. However, at long crystallization times and high crystallization
temperatures the redispersion of aluminum atoms can occur. All solids showed high
acidity which increased as a function of crystallinity. However, the samples prepared
at short times and low temperatures showed the majority of moderate acid sites of
medium strength, whereas those obtained at long times and high temperatures have
more strong acid sites. Thus, intermediate times and temperatures favor the formation
of solids having zeolitic characteristics and high mesoporosity.
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Preparation of Low-Valence Metal Oxide Monoliths with Three-Dimensionally Interconnected Macropores / 三次元マクロ孔をもつ低原子価金属酸化物モノリスの作製Lu, Xuanming 23 March 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22277号 / 理博第4591号 / 新制||理||1659(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
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Structural Characterisation of Hierarchically Porous Silica: Monolith by NMR Cryo-porometry and -diffusometryHwang, Seungtaik, Valiullin, Rustem, Haase, Jürgen, Smarsly, Bernd M., Bunde, Armin, Kärger, Jörg 11 September 2018 (has links)
A systematic NMR cryo-porometry and -diffusometry study using nitrobenzene as a probe liquid is carried out in order to characterise pore structures of hierarchically-organised porous silica monolith possessing mesopores along with a 3D bicontinuous macropore network. The result obtained from NMR cryoporometry shows the presence of a relatively wide mesopore size distribution of 10-35 nm. Furthermore, NMR cryodiffusometry indicates that whilst the mesopores are highly tortuous (Tmeso ≈6), they have little influence on the overall tortuosity of the material (Tmacro ≈1.5), which is largely dominated by the macropores (Toverall ≈1.7).
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Preparation and Application of Hierarchically Porous Monolithic Materials with Embedded Nanoscale Interfaces / ナノスケール界面を導入した階層的多孔構造をもつモノリス材料の合成と応用研究Yang, Zhu 23 March 2016 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19519号 / 理博第4179号 / 新制||理||1600(附属図書館) / 32555 / 京都大学大学院理学研究科化学専攻 / (主査)准教授 中西 和樹, 教授 北川 宏, 教授 有賀 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM
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Uniform exponential growth of non-positively curved groupsNg, Thomas Antony January 2020 (has links)
The ping-pong lemma was introduced by Klein in the late 1800s to show that certain subgroups of isometries of hyperbolic 3-space are free and remains one of very few tools that certify when a pair of group elements generate a free subgroup or semigroup. Quantitatively applying the ping-pong lemma to more general group actions on metric spaces requires a blend of understanding the large-scale global geometry of the underlying space with local combinatorial and dynamical behavior of the action. In the 1980s, Gromov publish a sequence of seminal works introducing several metric notions of non-positive curvature in group theory where he asked which finitely generated groups have uniform exponential growth. We give an overview of various developments of non-positive curvature in group theory and past results related to building free semigroups in the setting of non-positive curvature. We highlight joint work with Radhika Gupta and Kasia Jankiewicz and with Carolyn Abbott and Davide Spriano that extends these tools and techniques to show several groups with that act on cube complexes and many hierarchically hyperbolic groups have uniform exponential growth. / Mathematics
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Polymer-based mesoporous carbons: soft-templating synthesis, adsorption and structural propertiesGorka, Joanna 23 November 2010 (has links)
No description available.
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Synthèse des matériaux nanoporeux pour la décontamination moléculaire et le stockage d'énergie / Synthesis of nanoporous materials for molecular decontamination and energy storageKabalan, Ihab 05 January 2016 (has links)
Les composés organiques volatiles (COVs) sont les polluants organiques atmosphériques les plus abondants. Parmi les différentes solutions pour combattre cette pollution, l'utilisation d'adsorbants moléculaires tels que les zéolithes semble être efficace. Cependant les synthèses classiques de zéolithes aboutissent généralement à des tailles de cristaux de l'ordre de plusieurs dizaines de micromètres. Les capacités et les cinétiques de piégeage, sensibles aux phénomènes de diffusion et de surface pourraient potentiellement être améliorées par l'utilisation de nanocristaux ou de produits zéolithiques hiérarchisés (micro/mésoporeux). Dans ce travail de thèse, nous avons synthétisé des zéolithes aluminosiliciques ou purement siliciques de type structural FAU, MFI et *BEA. Ces dernières sont synthétisées avec différentes morphologies et tailles de particules telles que les nanocristaux et les zéolithes hiérarchisées (nanofeuillets et/ou nanoéponges en utilisant des agents structurants bifonctionnels). Ces matériaux sont comparés aux zéolithes conventionnelles, afin d'étudier l'influence de la morphologie sur la cinétique et la capacité de piégeage de COVs. Les caractéristiques structurales et texturales des zéolithes synthétisées ont été étudiées par ORX, MEB, manométrie d'adsorption/désorption de diazote, ATG-ATD, RMN du solide. Enfin, la capacité d'adsorption d'une molécule modèle, le n-hexane, au sein de ces zéolithes a été étudiée par thermogravimétrie. Dans le cas des zéolithes de type MFI et *BEA, les zéolithes hiérarchisées ont montré une augmentation de la capacité de piégeage en n-hexane par rapport aux zéolithes conventionnelles. La capacité de piégeage en n-hexane a été multipliée par 7 dans le cas des nanoéponges de type *BEA et par 6 dans le cas des nanocristaux de type *BEA comparés aux microcristaux de type *BEA (693 mg/g vs 103 mg/g et 591 mg/g vs 103 mg/g, respectivement). / Volatile organic compounds (VOCs) are the most abundant organic pollutants. Among the various solutions to fight against this pollution, the use of molecular adsorbents appears as a potential alternative for the control of contamination. The porous materials have many advantages due to their low cost, their physical characteristics and their useful properties related to their structure and their large surface area. However, conventional synthesis of zeolites generally lead to micrometer size crystals. The capacity and the kinetics of adsorption that are sensitive to the diffusion and the surface phenomena could be potentially improved by the use of zeolite nanocrystals or hierarchical products (micro / mesoporous). These nanomaterials have high potential due to their small size and their exalted outer surface that promote access of pollutants and improve the adsorption capacity. ln the thesis work, we synthesized zeolites with different structural types such as FAU, MFI and *BEA. Each structure type was synthesized in different morphologies such as nanosponges and /or nanosheets using a bifunctional structuring agent, as well as nanocrystals by the clear solution method. These materials were compared with conventional micrometer-sized zeolites. The purity and the porous texture have been characterized by using XRD, SEM, nitrogen adsorption/desorption techniques, TGA-DTA and solid state NMR. Finally, the adsorption capacity of a model molecule, the n-hexane, in these zeolites have been studied by thermogravimetry. In the case of *BEA and MFI-type zeol ites, the hierarchical zeolites showed an increase of the adsorption capacity of n-hexane compared to conventional zeolites. The adsorption capacity of n-hexane was multiplied by 7 in the case of *BEA-type nanosponges and by 6 in the case of the *BEA-type nanocrystals compared to *BEA_type microcrystals (693 mg / g vs 103 mg / g and 591 mg / g vs 103 mg / g, respectively).
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Bipolar nitrogen-doped graphene frameworks as high-performance cathodes for lithium ion batteriesHuang, Yanshan, Wu, Dongqing, Dianat, Arezoo, Bobeth, Manferd, Huang, Tao, Mai, Yiyong, Zhang, Fan, Cuniberti, Gianaurelio, Feng, Xinliang 17 July 2017 (has links) (PDF)
Hierarchically porous nitrogen-doped graphene frameworks (N-GFs) are fabricated through the ice-templating of GO with polyethylenimine and the thermal treatment of the resultant hybrids. As cathode materials in lithium ion batteries (LIBs), the obtained N-GFs exhibit an outstanding specific capacity of 379 mA h g−1 at 0.5 A g−1 for 2500 cycles. Even at an ultrahigh current density of 5 A g−1, the N-GFs maintain a capacity of 94 mA h g−1, superior to that of most reported LIB cathode materials. The experimental results and quantum mechanics calculations suggest that pyridinic-like N and pyridinic N-oxide in graphene are responsible for the excellent cathodic performance of the bipolar N-GFs by providing fast surface faradaic reactions with both p- and n-doped states.
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