130 research outputs found
Lim colim versus colim lim. I
No full textWe study a model situation in which direct limit () and inverse
limit () do not commute, and offer some computations of their
"commutator".
The homology of a separable metrizable space has two well-known
approximants: ("\v{C}ech homology") and ("\v{C}ech homology
with compact supports"), which are not homology theories but are nevertheless
interesting as they are and applied to
homology of finite simplicial complexes. The homomorphism , which is a special case of the natural map
, need not be either injective (P. S.
Alexandrov, 1947) or surjective (E. F. Mishchenko, 1953), but its surjectivity
for locally compact remains an open problem. In the case we obtain an
affirmative solution of this problem.
For locally compact , the dual map in cohomology is
shown to be surjective and its kernel is computed, in terms of and a
new functor . The original map is surjective and
its kernel is computed when is a "coronated polyhedron", i.e. contains a
compactum whose complement is a polyhedron.Comment: 32 pages, 3 figures; v3: Updated reference
ECH Structure: Evaluation and Analysis of Internal and External Structure of EUNIC Cluster Hungary.
No full textThe ECH (EUNIC Cluster Hungary) is a network which is promoting EU values under the umbrella organisation EUNIC (European Union National Institutes for Culture). The ECH objectives are to promote EU values through cooperation and events which are projecting the divers and the common characteristics of the countries. However there are problems which become evident in the current time where external problems clarify internal problems. The conservative movement, the financial crisis, the national institute leaders control and an ECH network which has been driven only on enthusiasm and mutual good relationships. The factors are many and the ECH network has not changed since its foundation in 2007, where a memorandum was created but never developed. The network’s missing foundation or structure is exactly the internal problem which is confusing the institute leaders and encouraging alternative directions for the network. Not having a structure to fall back on is creating a fundamental obstacle for ECH in the transforming environment and an ECH network which are subordinate as a marionette of national institutes.This assignment examines the problems in the structure from the perspective of the institute leaders, who are controlling the network, and also with firsthand knowledge/observations achieved by the author through his presence at the meetings and work at the events in ECH.The national institutes want more elaborate cooperation within the ECH, but at the same time the institutes are utilising the network to promote national related events, or events constructed by single national institutes in the network. This is a internal paradox for the institutes who want further and more elaborate internal cooperation in the network to meet the national interests. The paradox leads to changes in the internal structure to inhibit the national utilisation without losing the enthusiasm in the partnerships. An additional legislative solution toward the single institutes seems untenable toward the institutes already heavy burden in this area. The solution is back at the network’s foundation, which should be developed to focus more on European values in Hungarian society and this way encourages internal development toward a stronger network. This assignment first investigates the problems of the network and secondly through this investigation develops counter-measures to the problems. The decisions of the counter-measures are up to the institute leaders to apply and the product of their decisions have unintended consequences, which cannot be predicted for this assignment
Eco-efficiency improvements in the propylene-to-epichlorohydrin process
No full textBACKGROUND: Epichlorohydrin (ECH) production is an important industrial process, owing to its importance in windmill blade manufacture, but it suffers from several drawbacks such as high energy use, large wastewater production and low atom efficiency. This original study investigates a novel chlorohydrin-free technology with an enhanced separation system for ECH production. Rigorous process simulations were performed in Aspen Plus for the classic and novel processes, and a fair techno-economic and sustainability comparison was made between the new catalytic oxidation route and the classic chlorohydrin process. RESULTS: For the hydrogen peroxide (HP) process route, a novel separation system was developed using methanol as solvent, which enables high purity of ECH. Moreover, allyl chloride (ACH) purification was optimized using thermally coupled distillation to improve the energy efficiency of ACH production. The novel HP process provides 88% higher atom efficiency, about 10% higher yield and a smaller amount of by-products, as well as a 13% increase in production capacity and major savings of 98% in wastewater production, while also achieving lower energy use (<40 MJ kg−1 ECH) and reduced carbon dioxide emission (1.13 kg kg−1 ECH). CONCLUSION: The developed HP process route is feasible and economically viable. Also, it can be partly retrofitted to existing ECH plants based on the chlorohydrin route. As both processes use the same intermediate product, only the ECH part of a classic process would be replaced by the novel route, while keeping the common ACH part. This approach is the most profitable, as only 55% of capital expenditure is required for this modification, while the plant would benefit from all the improvements provided by the novel process.ChemE/Product and Process Engineerin
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Some results involving embedded contact homology
No full textThis dissertation is a collection of four papers involving embedded contact homology (ECH). ECH is a three-manifold invariant recently defined by Michael Hutchings. The dissertation covers both technical results about ECH (for example a proof that the absolute grading in ECH is a topological invariant) and applications of ECH to Reeb dynamics and symplectic embedding problems. All four papers were written while the author was a graduate student at UC Berkeley
Understanding the emergence of social protocols on MySpace: impact and its ramifications
No full textOver the recent years, MySpace has been vital to fostering the growth of independent musicians’ followings and have played critical roles in helping mainstream artists maintain fan communities. The popularity of MySpace has been accompanied by the establishment of social protocols which allow musicians to network with one another in an efficient and successful way. These protocols have inspired the publication of various books (such as «MySpace Music Profit Monster!: Proven Online Marketing Strategies!» by Nicky Kalliongis devoted to providing tips and strategies for musicians. While some of these protocols pertain to being savvy with the technological aspect of MySpace, other protocols are directly related to learning a particular manner to network on MySpace. Furthermore, these practices are considered a serious work as they require a lot of time and networking skills to achieve a certain level of success, i.e. increasing the number of friends on one’s network. Thus, this article examines the emerging social protocols on MySpace as a form of affective and immaterial labor. The author argues that the implementation of various tips as provided by MySpace expert will possibly have a regressive effect on musicians’ social networking practices as these could become a standardized and repetitive practice. As a whole, this article traces the evolution of MySpace, especially in regards to the decreasing popularity of the site as a current trend
The tympanic membrane displacement analyser for monitoring intracranial pressure in children
No full textPurpose: Raised intracranial pressure (ICP) is a potentially treatable cause of morbidity and mortality but tools for monitoring are invasive. We sought to investigate the utility of the tympanic membrane displacement (TMD) analyser for non-invasive measurement of ICP in children.
Methods: We made TMD observations on normal and acutely comatose children presenting to Kilifi District Hospital (KDH) at the rural coast of Kenya and on children on follow-up for idiopathic intracranial hypertension at Evelina Children’s Hospital (ECH), in London, UK.
Results: We recruited 63 patients (median age 3.3 (inter-quartile range (IQR) 2.0–4.3) years) at KDH and 14 children (median age 10 (IQR 5–11) years) at ECH. We observed significantly higher (more negative) TMD measurements in KDH children presenting with coma compared to normal children seen at the hospital’s outpatient department, in both semi-recumbent [mean −61.3 (95 % confidence interval (95 % CI) −93.5 to 29.1) nl versus mean −7.1 (95 % CI −54.0 to 68.3) nl, respectively; P = 0.03] and recumbent postures [mean −61.4 (95 % CI −93.4 to −29.3) nl, n = 59) versus mean −25.9 (95 % CI −71.4 to 123.2) nl, respectively; P = 0.03]. We also observed higher TMD measurements in ECH children with raised ICP measurements, as indicated by lumbar puncture manometry, compared to those with normal ICP, in both semi-recumbent [mean −259.3 (95 % CI −363.8 to −154.8) nl versus mean 26.7 (95 % CI −52.3 to 105.7) nl, respectively; P < 0.01] and recumbent postures [mean −137.5 (95 % CI −260.6 to −14.4) nl versus mean 96.6 (95 % CI 6.5 to 186.6) nl, respectively; P < 0.01].
Conclusion: The TMD analyser has a potential utility in monitoring ICP in a variety of clinical circumstances
Intensified Downstream Processing in Propylene to Epichlorohydrin Process
No full textThe modern chemical industry faces many challenges, such as energy transition. However, energy transition alone will not provide enough improvements to the industry to maintain profitability and increase sustainability. To achieve these goals, chemical processes have to be appropriately optimised, and only the synergy of these two factors can improve existing processes. Epichlorohydrin production is an important industrial process, but it suffers from several drawbacks such as high energy consumption, significant wastewater production, and low atom efficiency. This is caused by chlorohydrin-based technology, which requires operations in very diluted solutions. In this thesis, a novel chlorohydrin-free technology for ECH production was investigated. This approach could allow operation in more concentrated solutions, but this route is in the early development stage. One of the most crucial design parameters for this process is proper solvent selection. On the one hand methanol appears to be the most suitable compound for this purpose. On the other hand, some papers reported the separation system for this case to be infeasible due to several azeotropes present in the post-rection mixture. However, with proper constraints and understanding of components' azeotropic behaviour, a separation system, which enables obtaining high purity ECH, was created and applied to the production process. To perform a comparison between HP route and chlorohydrin process an Aspen Plus simulation of both processes were created. For the hydrogen peroxide route with methanol as solvent a novel separation system which enables high purities of ECH were created. Furthermore, possibilities to optimise distillation in the given process were investigated because this unit operation requires significant expenses in terms of CAPEX and OPEX. A review of advanced distillation techniques concludes that Dividing Wall Column distillation is the most suitable technique for this purpose. This technology was then applied to replace two columns, which purifies the intermediate Allyl Chloride (ACH) from the process. Aspen Plus simulations of both processes with and without applied DWC distillation were created to evaluate the influence of these improvements. Moreover, to establish the impact of DWC distillation, an Aspen Plus model of this apparatus was created. Simulation results indicate that this novel epoxidation reaction produces 98% less wastewater than the traditional process. Additionally, the novel approach offers a 10% higher yield and a smaller amount of by-products than the chlorohydrin process. Energy consumption per unit of ECH is also lower for the novel route. Application of DWC distillation led to 3.5% decrease in OPEX, while the CAPEX was smaller by almost 5%. These results indicate that applying a novel epoxidation route and DWC may benefit a given plant. However, more research needs to be performed to implement a novel process in the industry.Chemical Engineerin
Lim colim versus colim lim. II: Derived limits over a pospace
No full text\v{C}ech cohomology of a separable metrizable space is defined
in terms of cohomology of its nerves (or ANR neighborhoods) whereas
Steenrod-Sitnikov homology is defined in terms of homology of compact
subsets .
We show that one can also go vice versa: in a sense, can be
reconstructed from , and if is finite dimensional,
can be reconstructed from .
The reconstruction is via a Bousfield-Kan/Araki-Yoshimura type spectral
sequence, except that the derived limits have to be "corrected" so as to take
into account a natural topology on the indexing set. The corrected derived
limits coincide with the usual ones when the topology is discrete, and in
general are applied not to an inverse system but to a "partially ordered
sheaf".
The "correction" of the derived limit functors in turn involves constructing
a "correct" (metrizable) topology on the order complex of a partially
ordered metrizable space (such as the hyperspace of nonempty compact
subsets of with the Hausdorff metric). It turns out that three natural
approaches (by using the space of measurable functions, the space of
probability measures, or the usual embedding ) all lead
to the same topology on .Comment: 29 pages. v2: Minor changes (Proposition 3.5 from v1 has migrated to
arXiv:1106.3249, where it is now called Proposition 26.14
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Morse-Bott Embedded Contact Homology
No full textThis dissertation constructs a Morse-Bott version of embedded contact homology (ECH). The dissertation is comprised of two parts, corresponding to the two papers written by the author as a graduate student at UC Berkeley. The first part explains how to compute ECH in the Morse-Bott setting when certain transversality conditions are met and provided a certain correspondence theorem is true; and gives a large class of examples where the transversality conditions are satisfied. The second part provides the analytic foundations of the first part by giving a proof of the correspondence theorem
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