Comments on D-Instantons in c<1 Strings

We suggest that the boundary cosmological constant \zeta in c<1 unitary string theory be regarded as the one-dimensional complex coordinate of the target space on which the boundaries of world-sheets can live. From this viewpoint we explicitly construct analogues of D-instantons which satisfy Polchinski's ``combinatorics of boundaries.'' We further show that our operator formalism developed in the preceding articles is powerful in evaluating D-instanton effects, and also demonstrate for simple cases that these effects exactly coincide with the stringy nonperturbative effects found in the exact solutions of string equations.Comment: 12 pages with 1 figure, LaTex, Version to appear in PL

Public-private partnerships in space projects : an analysis of stakeholder dynamics

Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 102-107).In Public-Private Partnerships (PPPs), private partners assume more responsibility for public projects than in traditional approaches. The larger responsibility of the private partner is expected to improve efficiencies of the project. However, it also increases potential challenges such as conflicts of interest. If the dynamic structures which cause challenges in PPPs are identified, they will help to predict potential challenges in future PPP projects. Therefore, this research develops a dynamics model of which challenges arise in the application of PPP approaches to space projects. The PPP dynamics model is illustrated by using system dynamics modeling. In the first step, this research develops a traditional-approach model. In the second step, it proposes the PPP model, which is a modification of the traditional-approach model. In the third step, this research tests the PPP model by applying it to four space-related PPP cases: the European navigation system Galileo, the Japanese navigation system QZSS, the Japanese launch vehicle GX, and the U.S. launch vehicle families EELV. The PPP model passes these four tests. In the PPP model, three variables play important roles: conflicts of interest among parties, user satisfaction, and the private partner's revenue risk. The three variables represent interests of stakeholders such as the public sector, private partners, and users. Conflicts of interest among parties increase cost schedule inefficiencies. More cost schedule inefficiencies lead to less user satisfaction. Less user satisfaction results in more revenue risk for the private partner. More revenue risk for the private partner leads to more conflicts of interest among parties.(cont.) Thus, the interaction of stakeholder interests forms a reinforcing loop unique to PPPs. Additionally, unexpected technical and demand problems strengthen the reinforcement. This reinforcing loop and these unexpected problems are the inherent sources of challenges in space-related PPP projects. Lessons for improving the dynamic structures of space-related PPPs are (1) to set cost saving as the primary goal, (2) to choose the government customer market, and (3) to adopt conservative technical and demand forecasts. Based on these lessons, this research proposes that potential missions suitable for future space-related PPPs might be telecommunication, Earth observation, and meteorological monitoring for governments' use.by Masafumi Hashimoto.S.M.in Technology and Polic

Bovine Insulin Filaments Induced by Reducing Disulfide Bonds Show a Different Morphology, Secondary Structure, and Cell Toxicity from Intact Insulin Amyloid Fibrils

AbstractAmyloid fibrils are associated with more than 20 diseases, including Alzheimer's disease and type II diabetes. Insulin is a 51-residue polypeptide hormone, with its two polypeptide chains linked by one intrachain and two interchain disulfide bonds, and has long been known to self-assemble in vitro into amyloid fibrils. We demonstrate here that bovine insulin forms flexible filaments in the presence of a reducing agent, Tris (2-carboxyethyl) phosphine. The insulin filaments, possibly formed due to partial reduction of S-S bonds in insulin molecules, differ from intact insulin fibrils in terms of their secondary structure. The insulin filaments were determined to have an antiparallel β-sheet structure, whereas the insulin fibrils have a parallel β-sheet structure. Of importance, the cell toxicity of the insulin filaments was remarkably lower than that of the insulin fibrils. This finding supports the idea that cell toxicity of amyloids correlates with their morphology. The remarkably low toxicity of the filamentous structure should shed new light on possible pharmacological approaches to the various diseases caused by amyloid fibrils

Added Diagnostic Value of Cerebrospinal Fluid Carcinoembryonic Antigen in a Patient with Leptomeningeal Carcinomatosis as the Initial Manifestation of Gastric Cancer

A 77-year-old woman with no history of malignancy presented with anorexia and bilateral lower extremity weakness. Her consciousness level worsened daily, so we performed a lumbar puncture. Cerebrospinal fluid (CSF) analysis indicated meningitis, but three rounds of CSF cytology showed no malignant cells. The patient’s carcinoembryonic antigen (CEA) level was highly elevated in CSF, but normal in serum. Through gadolinium-enhanced brain/spinal magnetic resonance imaging and gastrointestinal endoscopy, she was diagnosed with leptomeningeal carcinomatosis (LC) from gastric cancer. CEA level in CSF facilitated the diagnosis of LC from gastric cancer because there were no malignant cells on CSF cytology

Evaluation of the GABAergic nervous system in autistic brain : 123I-iomazenil SPECT study

Purpose: To evaluate the GABAA receptor in the autistic brain, we performed 123I-IMZ SPECT in patients with ASD. We compared 123I-IMZ SPECT abnormalities in patients who showed intellectual disturbance or focal epileptic discharge on EEG to those in patients without such findings. Subjects and methods: The subjects consisted of 24 patients with ASD (mean age, 7.3±3.5years), including 9 with autistic disorder (mean age, 7.0±3.7years) and 15 with Asperger’s disorder (mean age, 7.5±3.2years). We used 10 non-symptomatic partial epilepsy patients (mean age, 7.8±3.6years) without intellectual delay as a control group. For an objective evaluation of the 123I-IMZ SPECT results, we performed an SEE (Stereotactic Extraction Estimation) analysis to describe the decrease in accumulation in each brain lobule numerically. Results In the comparison of the ASD group and the control group, there was a dramatic decrease in the accumulation of 123I-IMZ in the superior and medial frontal cortex. In the group with intellectual impairment and focal epileptic discharge on EEG, the decrease in accumulation in the superior and medial frontal cortex was greater than that in the group without these findings. Conclusion The present results suggest that disturbance of the GABAergic nervous system may contribute to the pathophysiology and aggravation of ASD, since the accumulation of 123I-IMZ was decreased in the superior and medial frontal cortex, which is considered to be associated with inference of the thoughts, feelings, and intentions of others (Theory of Mind)

Functional Expression and Characterization of Tetrachloroethene Dehalogenase From Geobacter sp.

Reductive dehalogenase (RDase) consists of two parts, RdhA and RdhB. RdhA is the catalytic subunit, harboring a cobalamin cofactor and two Fe–S clusters. RdhA is anchored to the cytoplasmic membrane via the membrane anchoring subunit, RdhB. There are many genes encoding RDases in the genome of organohalide-respiring bacteria, including Dehalococcoides spp. However, most genes have not been functionally characterized. Biochemical studies on RDases have been hampered by difficulties encountered in their expression and purification. In this study, we have expressed, purified and characterized RdhA of RDase for tetrachloroethene (PceA) from Geobacter sp. PceA was expressed as a fusion protein with a trigger factor tag in Escherichia coli. PceA was purified and denatured in aerobic condition. Subsequently, this protein was refolded in the presence of FeCl3, Na2S and cobalamin in anaerobic condition. The reconstituted PceA exhibited dechlorination ability for tetrachloroethene. UV-Vis spectroscopy has shown that it contains cobalamin and Fe-S clusters. Since this method requires anaerobic manipulation only in the reconstituting process and has a relatively high yield, it will enable further biochemical studies of RDases

The effects of switching daily teriparatide to oral bisphosphonates or denosumab in patients with primary osteoporosis

The aim of this 12-month, observational study was to compare the effects of switching daily teriparatide (TPTD) to oral bisphosphonates (BP) therapy or denosumab (DMAb) therapy in patients with primary osteoporosis. Patients [n = 78; 71 postmenopausal women and seven men; mean age 76.3 (64–94) years; mean duration of prior daily TPTD therapy 20.1 (6–24) months] were allocated to either the (1) “switch-to-BP” group [n = 36; weekly alendronate 35 mg (n = 19), weekly risedronate 17.5 mg (n = 12), monthly minodronate 50 mg (n = 5)]; or (2) “switch-to-DMAb” group (n = 42; 60 mg sc every 6 months) based on each physicians’ decision. Changes in bone mineral density (BMD) and serum bone turnover markers were monitored every 6 months. No significant difference was observed in baseline clinical characteristics between the groups. After 12 months, the increase in BMD was significantly greater in the switch-to-DMAb group compared to the switch-to-BP group: lumbar spine (6.2 vs. 2.6 %; P < 0.01), total hip (4.2 vs. 1.1 %; P < 0.05), and femoral neck (3.5 vs. 1.4 %; P < 0.05). In addition, the patients in the switch-to-DMAb group showed a significant decrease compared to those in the switch-to-BP group in TRACP-5b (−55.8 vs. −32.8 %; P < 0.01) and ucOC (−85.5 vs. −65.0 %; P < 0.001), while no significant difference was observed in PINP (−67.5 vs. −62.1 %). Switching daily TPTD to DMAb significantly increased BMD and decreased bone resorption marker compared to switching to oral BP at 12 months, and thus may provide an effective sequential treatment option after daily TPTD treatment.This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s00774-015-0731-xEbina K., Hashimoto J., Kashii M., et al. The effects of switching daily teriparatide to oral bisphosphonates or denosumab in patients with primary osteoporosis. Journal of Bone and Mineral Metabolism 35, 91 (2017); https://doi.org/10.1007/s00774-015-0731-x

Function of the frontal lobe in autistic individuals: a proton magnetic resonance spectroscopic study

Purpose. In this investigation, we studied differences in chemical metabolites in certain brain regions between autistic patients and normal control subjects. Methods. Proton magnetic resonance spectroscopy (1H-MRS) was used to evaluate functional activity in these regions. Specific regions studied were right and left dorsolateral prefrontal cortex(DLPFC) and the anterior cingulated cortex(ACC). Results. In the ACC, the N-acetylaspartate(NAA)/creatine/phosphocreatine(Cr) ratio in autistic patients (n=31) was significantly lower than that in control subjects (n=28). The decrease in the NAA/Cr ratio for the ACC was much greater in the group with worst social ability. NAA/Cr for the left DLPFC and social ability of autistic patients also correlated well. Furthermore, NAA/Cr for the left DLPFC in the group with intelligence quotient (IQ) below 50 was significantly less than in controls. NAA/Cr for the right DLPFC in autistic patients was not decreased compared to controls, and did not correlate with IQ or social ability. Conclusions. These findings suggest neuronal dysfunction in the ACC and left DLPFC in autism, and also a relationship between social disability and metabolic dysfunction in these regions. Dysfunction in the ACC and the left DLPFC may contribute to the pathogenesis of autism