Case Study In Operations Management

  This case study is conducted within the context of the Theory of Constraints. The field research reported in this document contains information specific to the telecommunications industry. An examination of the history, organization design, problems and solutions for one telecommunications company are undertaken from the perspective of academic work in the Theory of Constraints. The information included in this document was developed through interviews with four senior managers including the President, the Chief Technology Officer, a Vice President and a department manager. Their responses were the basis of identifying problems and undesirable effects. The undesirable effects were diagramed in six UDE clouds dealing with the following issues: 1- unclear vision from management to employees; 2- supplier; 3- market; 4- the price and regulation environment; 5- production; and 6- bureaucracy. These undesirable effects were logically examined until a single cloud depicting the core conflict was found. This core conflict is the company cannot simultaneously choose to make money over time through both conducting business as usual, and through means that are adapted to the environment and customer needs. Solutions tried to date by the company are explained. These solutions are reviewed from both and internal and external perspective. Alternative solutions are examined, as are obstacles to reaching the desired state. The case concludes with thoughts on the future desired state

A new humanized ataxin-3 knock-in mouse model combines the genetic features, pathogenesis of neurons and glia and late disease onset of SCA3/MJD

AbstractSpinocerebellar ataxia type 3 (SCA3/MJD) is a neurodegenerative disease triggered by the expansion of CAG repeats in the ATXN3 gene. Here, we report the generation of the first humanized ataxin-3 knock-in mouse model (Ki91), which provides insights into the neuronal and glial pathology of SCA3/MJD. First, mutant ataxin-3 accumulated in cell nuclei across the Ki91 brain, showing diffused immunostaining and forming intranuclear inclusions. The humanized allele revealed expansion and contraction of CAG repeats in intergenerational transmissions. CAG mutation also exhibited age-dependent tissue-specific expansion, which was most prominent in the cerebellum, pons and testes of Ki91 animals. Moreover, Ki91 mice displayed neuroinflammatory processes, showing astrogliosis in the cerebellar white matter and the substantia nigra that paralleled the transcriptional deregulation of Serpina3n, a molecular sign of neurodegeneration and brain damage. Simultaneously, the cerebellar Purkinje cells in Ki91 mice showed neurodegeneration, a pronounced decrease in Calbindin D-28k immunoreactivity and a mild decrease in cell number, thereby modeling the degeneration of the cerebellum observed in SCA3. Moreover, these molecular and cellular neuropathologies were accompanied by late behavioral deficits in motor coordination observed in rotarod and static rod tests in heterozygous Ki91 animals. In summary, we created an ataxin-3 knock-in mouse model that combines the molecular and behavioral disease phenotypes with the genetic features of SCA3. This model will be very useful for studying the pathogenesis and responses to therapy of SCA3/MJD and other polyQ disorders

Amenability of algebras of approximable operators

We give a necessary and sufficient condition for amenability of the Banach algebra of approximable operators on a Banach space. We further investigate the relationship between amenability of this algebra and factorization of operators, strengthening known results and developing new techniques to determine whether or not a given Banach space carries an amenable algebra of approximable operators. Using these techniques, we are able to show, among other things, the non-amenability of the algebra of approximable operators on Tsirelson's space.Comment: 20 pages, to appear in Israel Journal of Mathematic

Hastings' additivity counterexample via Dvoretzky's theorem

The goal of this note is to show that Hastings' counterexample to the additivity of minimal output von Neumann entropy can be readily deduced from a sharp version of Dvoretzky's theorem on almost spherical sections of convex bodies.Comment: 12 pages; v.2: added references, Appendix A expanded to make the paper essentially self-containe

Mechanical properties of diamond–TiB2 composites

The presented paper characterizes the basic mechanical and physical properties of sintered diamond-titanium diboride (submicro) and diamond-titanium diboride (nano) composites. The effect of reduction of powder size from the submicron scale to the nano scale of the ceramic bonding phase (TiB₂) in diamond composites on selected mechanical properties (Young’s modulus, Vickers hardness, fracture toughness, coefficient of friction) has been reported. Composites were prepared from initial powders of diamond (MDA36, Element Six) with addition of 10 mass % submicron TiB₂ (H.C. Starck F) and 10 mass % nanopowder TiB₂ (American Elements). Compacts were sintered at pressure 8±0,5 GPa and 2233±50 K using the high pressure-high temperature Bridgman type apparatus. These investigations allow the possibility of using this materials to be enhacced as ceramic tool materials, in particular as burnishing tools.Наведені основні механічні та фізичні властивості спечених композитів на основі алмазу з додаванням субмікро- та нано-дибориду титану. Вивчено вплив розміру частинок порошку від субмікронного до нано-рівня в керамічній (TiB₂) складовій алмазних композитів на їх механічні властивості (модуль Юнга, твердість за Віккерсом, в'язкість руйнування, коефіцієнт тертя). Композити були отримані з вихідних порошків алмазу (MDA36, Element Six) з додаванням 10 мас. % субмікронного TiB₂ (HC Starck F) або 10 мас. % нанопорошку TiB₂ (American Elements). Зразки спечені при тиску 8±0,5 ГПа і температурі 2233±50 К в апараті високого тиску типу тороїд. Результати досліджень вказують на можливість використання одержаних композитів як інструментальних матеріалів підвищеної якості, зокрема в інструментах для вигладжування.Приведены основные механические и физические свойства спеченных композитов на основе алмаза с добавками субмикро- и нано-диборида титана. Изучено влияние размера частиц порошка от субмикронного до нано-уровня в керамической (TiB₂) составляющей алмазных композитов на их механические свойства (модуль Юнга, твердость по Виккерсу, вязкость разрушения, коэффициент трения). Композиты были получены из исходных порошков алмаза (MDA36, Element Six) с добавлением 10 масс. % субмикронного TiB₂ (HC Starck F) или 10 масс. % нанопорошка TiB₂ (American Elements). Образцы были спечены при давлении 8±0,5 ГПа и температуре 2233±50 К в аппарате высокого давления типа тороид. Результаты исследований указывают на возможность использования полученных композитов в качестве улучшенных инструментальных материалов, в частности в выглаживающих инструментах

Exponential and moment inequalities for U-statistics

A Bernstein-type exponential inequality for (generalized) canonical U-statistics of order 2 is obtained and the Rosenthal and Hoffmann-J{\o}rgensen inequalities for sums of independent random variables are extended to (generalized) U-statistics of any order whose kernels are either nonnegative or canonicalComment: 22 page

Investigating the molecular guts of endoderm formation using zebrafish

The vertebrate endoderm makes major contributions to the respiratory and gastrointestinal tracts and all associated organs. Zebrafish and humans share a high degree of genetic homology and strikingly similar endodermal organ systems. Combined with a multitude of experimental advantages, zebrafish are an attractive model organism to study endoderm development and disease. Recent functional genomics studies have shed considerable light on the gene regulatory programs governing early zebrafish endoderm development, while advances in biological and technological approaches stand to further revolutionize our ability to investigate endoderm formation, function and disease. Here, we discuss the present understanding of endoderm specification in zebrafish compared to other vertebrates, how current and emerging methods will allow refined and enhanced analysis of endoderm formation, and how integration with human data will allow modeling of the link between non-coding sequence variants and human disease

Fabrication and performance of selectively oxidized vertical-cavity lasers

Includes bibliographical references.We report the high yield fabrication and reproducible performance of selectively oxidized vertical-cavity surface emitting lasers. We show that linear oxidation rates of AlGaAs without an induction period allows reproducible fabrication of buried oxide current apertures within monolithic distributed Bragg reflectors. The oxide layers do not induce obvious crystalline defects, and continuous wave operation in excess of 650 h has been obtained. The high yield fabrication enables relatively high laser performance over a wide wavelength span. We observe submilliamp threshold currents over a wavelength range of up to 75 nm, and power conversion efficiencies at 1 mW output power of greater than 20% over a 50-nm wavelength range.The work at Sandia National Laboratories was supported in part by the United States DOE under contract No. DE-AC04-94AL85000

In-situ uniaxial drawing of poly-L-lactic acid (PLLA): Following the crystalline morphology development using time-resolved SAXS/WAXS

Simultaneous synchrotron small- and wide-angle X-ray scattering (SAXS/WAXS) was used to follow the crystalline morphology evolution of poly-L- lactic acid (PLLA) during uniaxial deformation at various draw temperatures (Td). The mechanical behaviour of PLLA, was found to be strongly dependent on Td. 2D SAXS/WAXS data taken during the draw showed that at low Tds cavitation and voiding occurred and the initial crystallites underwent ‘overdrawing’ where they slip and are partially destroyed. SEM confirmed that surface voiding and cavitation had occurred at Td = 60 and 65 °C but was absent at higher Tds. During the draw, no long-range macromolecular lamellar structure was seen in the SAXS, but small crystallites of the disordered α′ crystal form of PLLA were observed in the WAXS at all Tds. The PLLA samples were then step annealed in a second processing stage (post-draw) to develop the oriented crystalline lamellar structure and increase the amount of the stable α crystalline form. SAXS/WAXS data showed that a highly oriented lamellar stack macrostructure developed on annealing, with increased crystallite size and crystallinity at all Tds. Furthermore, step annealing drove the crystalline transition in all samples from the disordered α′ crystal form to the stable α crystal form. Therefore, varying pre- and post-processing parameters can significantly influence the mechanical properties, orientation, crystalline morphology and crystal phase transition of the final PLLA material