527 research outputs found
Computational chemistry and molecular modeling : principles and applications / K.I. Ramachandran, G. Deepa, K. Namboori.
No full text"An exclusive URL (http://www.amrita.edu/cen/ccmm/) for this book with the required support materials has been provided for readers ..."--Preface.pharmacy bookfair2015Includes bibliographical references and index.xxi, 397 pages
Micro-raman spectroscopy of caries lesion formation in dental enamel
No full textCaries lesions form by a complex process of chemical interactions between dental enamel and its environment. They can cause cavities and pain, and are expensive to fix. Lesions form by slow demineralization over many months, even years. It is hard to characterize in vivo as a result of environmental factors and remineralization by ions in the oral cavity. In this thesis the process of demineralization was carried out in vitro and micro-Raman spectroscopy used to investigate and characterize the lesion's chemistry. Demineralization occurs by diffusion across the depth of the lesion of mineral ions via interstitial spaces in the dental enamel. Hydroxyl ions are initially lost by acidic attack, which increases the interstitial space. The demineralization is retarded by diffusion processes in the opposite direction, and a balance in the charges of the ions must be maintained. Having multiple ions diffusing simultaneously is termed “coupled diffusion”. A subsurface highly demineralized region is formed, but this can be remineralized.
Micro-Raman spectroscopy is a powerful tool for studying material composition by exciting chemical bonds in the sample. Using micro-Raman to characterize the chemical composition of lesions may help in developing preventative measures to stop their formation. Raman (λ=785 nm) was used to characterize lesions grown over 5, 7, 9, 11 and 14 days. The amide I peak at ~1605 cm-1, which has not been observed previously, was seen in the maturing lesions. The extreme demineralization in these lesions enables the organic peaks to be seen rather than the normally stronger mineral peaks. Analysis of crystallinity shows that there is always a reduction in mineral content with distance below the enamel surface, but this becomes magnified as the lesion matures. Type B carbonate substitution for phosphate ions can also be examined with Raman. Correcting for crystallinity shows that both carbonate and phosphate ions are lost at the same rate during demineralization.
In summary, micro-Raman is an effective and relatively easy tool to use in lesion characterization. It also has the advantage that it can be used to identify changes in both the mineral and protein phases of enamel.M.S.Includes bibliographical references (p. 53-55)
High Performance Integrated Circuit Blocks for High-IF Wideband Receivers
No full textDue to the demand for high���performance radio frequency (RF) integrated circuit
design in the past years, a system���on���chip (SoC) that enables integration of analog and
digital parts on the same die has become the trend of the microelectronics industry. As
a result, a major requirement of the next generation of wireless devices is to support
multiple standards in the same chip���set. This would enable a single device to support
multiple peripheral applications and services.
Based on the aforementioned, the traditional superheterodyne front���end
architecture is not suitable for such applications as it would require a complete receiver
for each standard to be supported. A more attractive alternative is the highintermediate
frequency (IF) radio architecture. In this case the signal is digitalized at an
intermediate frequency such as 200MHz. As a consequence, the baseband operations,
such as down���conversion and channel filtering, become more power and area efficient
in the digital domain. Such architecture releases the specifications for most of the front���end building blocks, but the linearity and dynamic range of the ADC become the
bottlenecks in this system. The requirements of large bandwidth, high frequency and
enough resolution make such ADC very difficult to realize. Many ADC architectures
were analyzed and Continuous���Time Bandpass Sigma���Delta (CT���BP�������) architecture was
found to be the most suitable solution in the high���IF receiver architecture since they
combine oversampling and noise shaping to get fairly high resolution in a limited
bandwidth.
A major issue in continuous���time networks is the lack of accuracy due to powervoltage���
temperature (PVT) tolerances that lead to over 20% pole variations compared
to their discrete���time counterparts. An optimally tuned BP ���� ADC requires correcting
for center frequency deviations, excess loop delay, and DAC coefficients. Due to these
undesirable effects, a calibration algorithm is necessary to compensate for these
variations in order to achieve high SNR requirements as technology shrinks.
In this work, a novel linearization technique for a Wideband Low���Noise
Amplifier (LNA) targeted for a frequency range of 3���7GHz is presented. Post���layout
simulations show NF of 6.3dB, peak S21 of 6.1dB, and peak IIP3 of 21.3dBm,
respectively. The power consumption of the LNA is 5.8mA from 2V.
Secondly, the design of a CMOS 6th order CT BP������� modulator running at 800
MHz for High���IF conversion of 10MHz bandwidth signals at 200 MHz is presented. A
novel transconductance amplifier has been developed to achieve high linearity and high
dynamic range at high frequencies. A 2���bit quantizer with offset cancellation is alsopresented. The sixth���order modulator is implemented using 0.18 um TSMC standard
analog CMOS technology. Post���layout simulations in cadence demonstrate that the
modulator achieves a SNDR of 78 dB (~13 bit) performance over a 14MHz bandwidth.
The modulator���s static power consumption is 107mW from a supply power of �� 0.9V.
Finally, a calibration technique for the optimization of the Noise Transfer
Function CT BP ���� modulators is presented. The proposed technique employs two test
tones applied at the input of the quantizer to evaluate the noise transfer function of
the ADC, using the capabilities of the Digital Signal Processing (DSP) platform usually
available in mixed���mode systems. Once the ADC output bit stream is captured,
necessary information to generate the control signals to tune the ADC parameters for
best Signal���to���Quantization Noise Ratio (SQNR) performance is extracted via Least���
Mean Squared (LMS) software���based algorithm. Since the two tones are located
outside the band of interest, the proposed global calibration approach can be used
online with no significant effect on the in���band content
Corrections to “An Improved Harmonics Mitigation Scheme for a Modular Multilevel Converter” [2019 147244-147255]
No full textIn the above-named work, T. Deepa should have been listed as the second co-author of the article with the affiliation of (1): School of Electrical Engineering, Vellore Institute of Technology, Chennai 600127, India. The author's biography is also provided within this correction. Additionally, the correct zip code of affiliation (1) should be 600127, and the correct statement on financial support acknowledgement should be as follows: "This work was funded by the Renewable Energy Laboratory, Department of Communications and Networks Engineering, Prince Sultan University, Riyadh, Saudi Arabia." It is necessary to mention the nature of funding provided by Prince Sultan University and to note the correction in the spelling of the university in the same statement in the published manuscript
Creating Value Through Design: Company and Country Perspectives from East Asia
No full textFor the final Y.B. Min lecture of the semester, the Center for Asian Business welcomed Deepa Prahalad, an author and business strategist specializing in opportunities at the intersection of consumer experience, technology and strategy. In her presentation, titled “Creating Value through Design: Company and Country Perspectives from East Asia,” Prahalad discussed the role of design in creating value, the ingredients of good design and how this applies to Asian countries in particular.
Prahalad discussed the success of great brands such as Apple, Nike, Coca-Cola and Samsung and how they have created awareness of the value of design to business. Design today is an important source of strategic advantage for entrepreneurs, established companies and countries. Her talk focused on case studies of how companies and countries have used design to build brands and create a sphere of influence.
According to Prahalad, strategic challenges such as co-creation, customer experience, globalization, innovation and new business model creation all require design. Today, we’re seeing a convergence of brand and design. Leading brands such as Nike, Apple, McDonald’s and Mercedes are all identifiable by their logo alone. These brands have a distinct look, feel and experience, and the experience must be valued by the consumers. Prahalad went on to address how emotional connections often lead to business results.
At the conclusion of her lecture, she highlighted the following points: Behavior is as important as income There is a convergence of quantitative and qualitative data Looking at emotions creates obligations for companies A great design still needs a great business model
Passionate about emerging markets and innovation, Prahalad has worked as a management consultant with firms from start-ups to large multinationals. She researched and co-authored the book, Predictable Magic: Unleash the Power of Design Strategy to Transform Your Business. Prahalad speaks on design strategy and emerging markets at business schools and at global and government forums on the importance of design as a competitive innovation. Prahalad received a B.A. in Economics and Political Science from the University of Michigan and an MBA from the Tuck School of Business at Dartmouth.https://digitalcommons.lmu.edu/ybminlectureseries/1003/thumbnail.jp
Childhood obesity is associated with shorter leukocyte telomere length
No full textCONTEXT: Obesity in adults is associated with shorter mean leukocyte telomere length (LTL), a marker of biological age that is also associated with age-related conditions including cardiovascular disease and type 2 diabetes. However, studies of childhood obesity and LTL have proved inconclusive. OBJECTIVE: The objective of the study was to clarify the relationship between telomere length and childhood obesity by measuring the average LTL in a large case-control cohort. PARTICIPANTS AND METHODS: LTL was measured in 793 French children aged 2-17 yr (471 with early onset obesity and 322 nonobese controls) using multiplex quantitative real-time PCR. The average LTL in the two groups was compared, and the relationships between telomere length and selected anthropometric and biochemical measurements were examined. RESULTS: Obese children had a mean LTL that was 23.9% shorter than that of nonobese children (P < 0.0001). Telomere length was inversely associated with age (R = -0.17, P = 0.002 in controls; R = -0.15, P = 0.001 in cases), log weight (R= -0.13, P = 0.017 in controls; R = -0.16, P = 0.0004 in cases), and height (R = -0.15, P = 0.008 in controls; R = -0.17, P = 0.0002 in cases). The mean LTL of girls and boys was not significantly different in either the cases or controls or in the group overall. CONCLUSION: Obese girls and boys have significantly shorter leukocyte telomeres than their nonobese counterparts, a finding that highlights a potentially deleterious impact of early onset obesity on future health.Published versio
Brazil's sugarcane sector : a case of lost opportunity
No full textThe Brazilian sugar and ethanol story goes like this: direct market intervention overrides market forces. Markets undergo dramatic change. Intervention establishes vested interests. Rent-seeking blocks adjustment to market change. Economic objectives become blurred behind political objectives. Opportunities go begging. Industry profitability suffers. And national income is forgone. The authors use a simple economic model of the Brazilian sugarcane sector and policy interventions to measure the costs of existing policies and to develop better policies. Brazil is an efficient producer of sugar, but policy intervention has caused: (a) underproduction of sugar cane (too much ethanol, not enough sugar); (b) missed opportunities to market ethanol in high-value uses (as an octane enhancer and clean fuel); (c)missed opportunities to make the world sugar market more competitive. Adopting more market-based policies could be worth billions of additional dollars annually to Brazil.Environmental Economics&Policies,Crops&Crop Management Systems,Economic Theory&Research,Transport and Environment,Access to Markets
Are there synergies between World Bank partial credit guarantees and private lending?
No full textSince 1994, the World Bank has provided partial credit guarantees to private financiers of several large infrastructure projects in developing countries. A major objective of the partial guarantee program is to leverage Bank resources so as to provide developing countries with better private credit terms. A real test of the efficacy of World Bank partial credit guarantees is whether they also lower the interest rate and lengthen the effective maturity of the part of the credit not covered by the World Bank guarantee. On the basis of deals closed so far, the author finds no evidence that guarantees have affected nonguaranteed interest rates favorably, while the duration of the nonguaranteed credits remains relatively short.International Terrorism&Counterterrorism,Payment Systems&Infrastructure,Banks&Banking Reform,Economic Theory&Research,Strategic Debt Management,Financial Crisis Management&Restructuring,Banks&Banking Reform,Economic Theory&Research,Strategic Debt Management,Insurance&Risk Mitigation
Migratory TCP: highly available internet services using connection migration
No full textWe evaluate the feasibility of using Migratory TCP (M-TCP), a reliable connection-oriented transport layer protocol that supports connection migration, for building highly available Internet services. M-TCP can transparently migrate the server endpoint of a live connection and assists server applications in resuming service on migrated connections. M-TCP provides a generic solution for the problem of service continuity and availability in the face of connectivity failures.
We have implemented M-TCP and present results of an experimental evaluation which shows it can efficiently provide support for highly available services. We illustrate the use of M-TCP in two applications. The first is a synthetic generic media streaming server. We show that, when the performance of the current server degrades, M-TCP an sustain throughput lose to the average server behavior by migrating connections to better servers. The second application is a transactional database server in which we have integrated support for migrating client connections. Using our system, a database frontend an continue the execution of a series of transactions submitted by a remote client in a session started with another front-end. The system allows a session to survive adverse conditions by connection migration, while ensuring that ACID semantics are preserved and that the execution is deterministic across migration.Technical report DCS-TR-46
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