California Institute Of Technology Research Articles

Mapping the use of open access resources by doctoral students in the USA by employing citation analysis

PurposeThe purpose of this paper is to measure the fully open access (OA) contents cited by researchers from top three universities in the USA (MIT, CIT and Stanford) in the field of physics. This study aims to identify the core fully OA journals widely used by researchers in the field of physics and evaluate the cited fully OA resources by applying various scientometric parameters to check the credibility of these OA resources.Design/methodology/approachThe PhD theses awarded during 2014 in the field of physics and hosted in the institutional repositories of Massachusetts Institute of Technology (MIT), California Institute of Technology (CIT) and Stanford University, respectively, were selected and scanned to extract references of sources cited. Later on, Google Scholar was used to identify source journals of the extracted references. Only source “journals” were selected and analyzed; rest of other sources were ignored; accordingly, toll-access and OA journals were segregated, as such the OA-cited journals could be identified. The scientometric performance indicators were used to check the quality of identified core fully OA journal cited by USA researchers in the field of physics.FindingsThe results of this study show that fully OA resources are sufficiently used by the researchers of top three academic institutions of the world/USA. The study was also successful in identifying the core fully OA journals; besides it also reveals that these fully OA journals are highly impressive as showed by performance indicators applied. The major finding of the research includes the identification of top ten fully OA journals along with their impact based on different scientometric parameters like number of times cited, impact factor, h-index, immediacy index, impact per publication and Scimago Journal Rank (SJR).Research limitations/implicationsBecause of a limited corpus of literature scrutinized in this study, the findings of the study may or may not represent the global picture in the field of physics.Practical implicationsThe paper confirms that fully OA resources usage trend is positively increasing day by day, and there are vast numbers of core OA journals with high-quality impact available for use to researchers around the world. Besides, the paper also affirms the view that there should be more publicity of fully OA literature around the globe to reap the benefits of the same.Social implicationsThis paper will assist researchers, libraries, information centers and research and development institutions to take a cost-efficient approach in using and disseminating the scholarly literature.Originality/valueThis paper is one of the first pieces of research conducted on electronic theses and dissertation (ETD’s) in top three universities of the USA, to check usage percentage and quality of fully OA journal resources cited by doctoral students in the field of physics.

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OPINION Reactions ShareShare onFacebookTwitterWechatLinked InRedditEmail C&EN, 2018, 96 (40), p 3October 8, 2018Cite this:C&EN 96, 40, 3(Credit: Will Ludwig/C&EN/Shutterstock)Figure1of1▸ Letters to the editor Graduate student journeys The “Chemistry Grad School Experience” issue (C&EN, Sept. 10, page 16) spent most of its time on negative aspects of a Ph.D. program. But that is not how I remember it.Getting a chemistry Ph.D. can be a wonderful experience and a special time that is unlikely to be repeated in any career. Once you get past whatever coursework and exams are required, there is an extended period where all you really have to do is research. You have no other obligations—no meetings, no schedule, no one monitoring your working hours. Just come in and do experiments, calculations, whatever, until you are too tired to go on; sleep, wake up when you want to, and do some more research.It is also a time of being in a close community—your own research group and all the other chemistry graduate students. If you are lucky, as I was, you also develop a very close relationship with your thesis adviser and possibly with other faculty, and you begin to become a part of the larger community of your area of research through attending meetings, meeting visiting scientists, and listening to seminars.I wish that the issue, which had much good advice, had done a bit more to capture the pleasure and privilege of getting a Ph.D. in chemistry.Bernard J. Bulkin London I am writing in response to the article by Mitch Jacoby in the Sept. 10 issue (page 20). I was a young assistant professor at the University of Wisconsin, Eau Claire, in 1966 when my research assistant applied to four graduate schools in chemistry: Harvard University, Massachusetts Institute of Technology, California Institute of Technology, and the University of California, Berkeley. He received offers from all four! He asked which one I would recommend, and my comment was they are all excellent. The next day he told me that he would attend Caltech. I asked, Why? He had been watching a popular TV show called “The Man From U.N.C.L.E.,” and it had filmed scenes in labs at Caltech. That convinced him! He earned his Ph.D. under professor Harry Gray in 1971 and never left. George Rossman is now a professor of mineralogy and is a world authority on gemstones. My former student is now a “rock star”! Allen A. Denio Newark, Del. Correction Sept. 3, page 8: The news story about an 18-electron alkaline earth metal complex incorrectly describes a spectroscopic shift as being to a lower wavelength. The shift was to a longer wavelength.

Advice for my grad school self

If you could go back to grad school, what do you wish you had known? We asked this question of members of our Talented 12 (T12) and the CAS SciFinder Future Leaders (SFFL). Here are their words of wisdom. Share your advice on social media using the hashtag #chemgradlife. “Attend more seminars from outside your subfield. It will help you be creative with your research ideas later on.”—Joseph Moran, assistant professor at the University of Strasbourg, T12 ’18 “I wish I would have realized sooner how important time away from the lab was, since the benefits vastly outweigh the small loss of hours at the bench.”—Julian West, postdoc at California Institute of Technology, CAS SFFL ’18 “Don’t be afraid to fail. Not only will it happen a lot, but you also get the opportunity to learn from it and maybe even discover something interesting.”—Roxanne Kieltyka, assistant professor at Leiden University,

Competitive Tuning Among Ca2+/Calmodulin-Dependent Proteins: Analysis of in silico Model Robustness and Parameter Variability.

Calcium/Calmodulin-dependent (Ca2+/CaM-dependent) regulation of protein signaling has long been recognized for its importance in a number of physiological contexts. Found in almost all eukaryotic cells, Ca2+/CaM-dependent signaling participates in muscle development, immune responses, cardiac myocyte function and regulation of neuronal connectivity. In excitatory neurons, dynamic changes in the strength of synaptic connections, known as synaptic plasticity, occur when calcium ions (Ca2+) flux through NMDA receptors and bind the Ca2+-sensor calmodulin (CaM). Ca2+/CaM, in turn, regulates downstream protein signaling in actin polymerization, receptor trafficking, and transcription factor activation.The activation of downstream Ca2+/CaM-dependent binding proteins (CBPs) is a function of the frequency of Ca2+ flux, such that each CBP is preferentially "tuned" to different Ca2+ input signals. We have recently reported that competition among CBPs for CaM binding is alone sufficient to recreate in silico the observed in vivo frequency-dependence of several CBPs. However, CBP activation may strongly depend on the identity and concentration of proteins that constitute the competitive pool; with important implications in the regulation of CBPs in both normal and disease states. Here, we extend our previous deterministic model of competition among CBPs to include phosphodiesterases, AMPAR receptors that are important in synaptic plasticity, and enzymatic function of CBPs: cAMP regulation, kinase activity, and phosphatase activity. After rigorous parameterization and validation by global sensitivity analysis using Latin Hypercube Sampling (LHS) and Partial Rank Correlation Coefficients (PRCC), we explore how perturbing the competitive pool of CBPs influences downstream signaling events. In particular, we hypothesize that although perturbations may decrease activation of one CBP, increased activation of a separate, but enzymatically-related CBP could compensate for this loss, providing a homeostatic effect. First we compare dynamic model output of two models: a two-state model of Ca2+/CaM binding and a four-state model of Ca2+/CaM binding. We find that a four-state model of Ca2+/CaM binding best captures the dynamic nature of the rapid response of CaM and CBPs to Ca2+ flux in the system. Using global sensitivity analysis, we find that model output is robust to parameter variability. Indeed, although variations in the expression of the CaM buffer neurogranin (Ng) may cause a decrease in Ca2+/CaM-dependent kinase II (CaMKII) activation, overall AMPA receptor phosphorylation is preserved; ostensibly by a concomitant increase in adenylyl cyclase 8 (AC8)-mediated activation of protein kinase A (PKA). Indeed phosphorylation of AMPAR receptors by CaMKII and PKA is robust across a wide range of Ng concentrations, though increases in AMPAR phosphorylation is seen at low Ng levels approaching zero. Our results may explain recent counter-intuitive results in neurogranin knockout mice and provide further evidence that competitive tuning is an important mechanism in synaptic plasticity. These results may be readily translated to other Ca2+/CaM-dependent signaling systems in other cell types and can be used to suggest targeted experimental investigation to explain counter-intuitive or unexpected downstream signaling outcomes.Tamara Kinzer-Ursem is an Assistant Professor in the Weldon School of Biomedical Engineering. She received her B.S. in Bioengineering from the University of Toledo and her M.S. and Ph.D. degrees in Chemical Engineering from the University of Michigan, and her post-doctoral training in Molecular Neuroscience at the California Institute of Technology. Prior to joining Purdue she was the Head of R&D in Biochemistry at Maven Biotechnologies and Visiting Associate in Chemical Engineering at the California Institute of Technology.Research in the Kinzer-Ursem lab focuses on developing tools to advance quantitative descriptions of cellular processes and disease within three areas of expertise: 1) Using particle diffusivity measurements to quantify biomolecular processes. Particle diffusometry is being used as a sensitive biosensor to detect the presence of pathogens in environmental and patient samples. 2) Development of novel protein tagging technologies that are used to label proteins in vivo to enable quantitative description of protein function and elucidate disease mechanisms. 3) Computational modeling of signal transduction mechanisms to understand cellular processes. Using computational techniques, we have recently described "competitive tuning" as a mechanism that might be used to regulate information transfer through protein networks, with implications in cell behavior and drug target analysis.

Mentorship comes from many sources.

Shubha Tole obtained her BSc in Life Sciences and Biochemistry from St. Xavier’s College, Mumbai, India, in 1987. After a PhD from the California Institute of Technology in 1994, she did her postdoc at the University of Chicago. In 1999, she joined the Tata Institute of Fundamental Research, in Mumbai, as a faculty member.

Machine learning predicts electron energies

When chemists want to model the structural and electronic properties of atoms or molecules, they often turn to a computational technique called density functional theory (DFT). When DFT fails, chemists use approaches like coupled cluster (CC) or Moller–Plesset perturbation (MP2) theories. These generate more reliable values than DFT does, but they require thousands of times as much computational power as DFT, even for small molecules. Thomas F. Miller and colleagues at California Institute of Technology now demonstrate that machine learning might be the best of both worlds—as accurate as CC or MP2 and no more costly than DFT (J. Chem. Theory Comput. 2018, DOI: 10.1021/acs.jctc.8b00636). The researchers wanted to predict electronic structure correlation energies—a measure of interactions between electrons that helps chemists model how a molecule behaves. Their machine-learning approach predicts these values based on a set of known data. Miller’s group trained its algorithm on localized molecular orbitals of

Evaluation of Pre-Trained Convolutional Neural Network Models for Object Recognition

This paper aims to evaluate the accuracy performance of pre-trained Convolutional Neural Network (CNN) models, namely AlexNet and GoogLeNet accompanied by one custom CNN. AlexNet and GoogLeNet have been proven for their good capabilities as these network models had entered ImageNet Large Scale Visual Recognition Challenge (ILSVRC) and produce relatively good results. The evaluation results in this research are based on the accuracy, loss and time taken of the training and validation processes. The dataset used is Caltech101 by California Institute of Technology (Caltech) that contains 101 object categories. The result reveals that custom CNN architecture produces 91.05% accuracy whereas AlexNet and GoogLeNet achieve similar accuracy which is 99.65%. GoogLeNet consistency arrives at an early training stage and provides minimum error function compared to the other two models.

What Is the Alternative Hypothesis to Market Efficiency?

1. Bradford Cornell 1. is a professor of financial economics at the California Institute of Technology in Pasadena, CA. (bcornell{at}caltech.edu) 1. To order reprints of this article, please contact David Rowe at d.rowe{at}pageantmedia.com or 646-891-2157. On repeated occasions

A multifrequency radio continuum study of the Magellanic Clouds – I. Overall structure and star formation rates

This scientific work makes use of the Murchison Radio-astronomy Observatory, operated by CSIRO. We acknowledge the Wajarri Yamatji people as the traditional owners of the Observatory site. Support for the operation of the Murchison Widefield Array is provided by the Australian Government (NCRIS), under a contract to Curtin University administered by Astronomy Australia Limited. We acknowledge the Pawsey Supercomputing Centre which is supported by the Western Australian and Australian Governments and the Centre of Excellence for All-sky Astrophysics (CAASTRO), which is an Australian Research Council Centre of Excellence, funded by grant CE110001020. Parts of this research were conducted with the support of Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. This research also made use of Montage. Montage is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration’s Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology.

Solving problems with hydrogen production in microgravity

Long-term space missions will require methods to produce fuels, such as hydrogen gas, on demand. Photoelectrochemical cells (PECs) can produce hydrogen using energy from sunlight, but the reduced gravity in space presents unique challenges to this chemistry. An international team of researchers led by California Institute of Technology’s Hans-Joachim Lewerenz studied one of these low-gravity problems and demonstrated how a nanostructured catalyst surface could solve it (Nat. Commun. 2018, DOI: 10.1038/s41467-018-04844-y). The team’s PEC consists of an electrode made of a light-absorbing semiconductor, p-type indium phosphide, coated with a catalytic layer of rhodium. When exposed to light, the electrode reduces hydrogen cations from an acidic water solution, producing hydrogen gas. To simulate the microgravity conditions of space, the researchers catapulted the device 120 meters into the air and allowed it to fall in a specialized tower in Germany. During the tests, hydrogen bubbles accumulated on the fla...

Practical Applications of Information Flow and Expected Inflation: An Empirical Analysis

In Information Flow and Expected Inflation: An Empirical Analysis , published in the Winter 2017 issue of The Journal of Investing , Bradford Cornell , a professor of financial economics at the California Institute of Technology in Pasadena, California, reviewed data from January 1, 2003 through November 10, 2015 to determine what news prompts a significant move in the breakeven inflation rate (BEI). His analysis indicates that the BEI responds frequently to news stories about changes in Federal Reserve interest rate policy or news related to overall economic activity and aggregate demand. In contrast, announcements related to inflation data, money supply, or fiscal policy do not seem to consistently trigger significant shifts in the BEI.

2D (r–z) numerical simulations of the plasma and channel erosion in a 100 kW class nested Hall thruster**© 2018. California Institute of Technology. Government sponsorship acknowledged.

Results from the first numerical simulations of a nested Hall thruster (NHT) are presented. The X3 is a 100 kW class thruster with one center-mounted hollow cathode and three acceleration channels none of which is currently magnetically shielded. The simulations were conducted with the r–z axisymmetric code Hall2De and focused on operation with all three channels firing, at discharge voltages of 300, 400 and 800 V. The corresponding discharge power levels are 38, 49.6 and 100 kW. A recent experimental campaign provided measurements of the thrust for a wide range of channel combinations and operating conditions, but not at 800 V. At 300 and 400 V, with all three channels operating, the computed thrust is underestimated by 8.4% and 4.7%, respectively. The simulations also allowed for the first estimates of erosion by ion sputtering in a NHT. The maximum erosion rates along the boron nitride channel walls are found to be in the order of 1 mm kh−1 (103 μm kh−1) at 300 V. The rates at 800 V are a few times higher than those at 300 V. Mechanisms driving the erosion are identified, in part through comparisons with measurements and simulations of a similar single-channel unshielded Hall thruster that has been extensively studied in the past. It is found that anomalous collisions, now widely accepted to drive electron transport in these devices, and the manner in which they develop spatially in the channel interior can play a significant role on the channel erosion.

Années du singe

The narrator, who left Huê in 1968, returns thirty-six years later with questions about her past. She wanders through familiar yet oddly unrecognisable streets, in search of memories of Têt Mâu Thân and the fateful offensive that would change the course of the war. 
 
 La narratrice, qui a quitté Huê en 1968, revient trente-six ans plus tard avec des questions sur son passé. Elle erre dans des rues à la fois familières et étrangement méconnaissables, à la recherche de ses souvenirs du Têt Mâu Thân et de cette offensive qui allait infléchir le cours de la guerre.

Reactive uptake of ammonia by secondary organic aerosols: Implications for air quality

Reactions between ammonia (NH3) and organic compounds containing carbonyl functional groups in aerosol particles can form organic products that are less basic than NH3 and are thus unable to neutralize efficiently nitric and sulfuric acids. In this exploratory study, the University of California, Irvine - California Institute of Technology (UCI-CIT) model is used to investigate the potential air quality impacts of including of the chemical uptake of NH3 by secondary organic aerosols (SOA) in a regional airshed model. A surface reaction of NH3 with SOA is implemented into the model to determine the impact of this process on NH3 and PM2.5 concentrations in the South Coast Air Basin of California (SoCAB). Air quality simulations are conducted using uptake coefficients ranging from 10−5 to 10−2 to explore the sensitivity of changes in NH3 and PM2.5 concentrations to the magnitude of the uptake coefficient. Results indicate that the chemical uptake of NH3 by SOA can potentially deplete gaseous NH3 concentrations, causing indirect reductions in the amount of ammonium nitrate and ammonium sulfate in particulate matter. The magnitude of the impact on NH3 and PM2.5 concentrations exhibits a strong but non-linear dependence on the value of the uptake coefficient, with evidence for small but notable impacts on air quality even with the lowest assumed uptake coefficient of 10−5.

CO2 Transport, Variability, and Budget over the Southern California Air Basin Using the High-Resolution WRF-VPRM Model during the CalNex 2010 Campaign

AbstractTo study regional-scale carbon dioxide (CO2) transport, temporal variability, and budget over the Southern California Air Basin (SoCAB) during the California Research at the Nexus of Air Quality and Climate Change (CalNex) 2010 campaign period, a model that couples the Weather Research and Forecasting (WRF) Model with the Vegetation Photosynthesis and Respiration Model (VPRM) has been used. Our numerical simulations use anthropogenic CO2 emissions of the Hestia Project 2010 fossil-fuel CO2 emissions data products along with optimized VPRM parameters at “FLUXNET” sites, for biospheric CO2 fluxes over SoCAB. The simulated meteorological conditions have been validated with ground and aircraft observations, as well as with background CO2 concentrations from the coastal Palos Verdes site. The model captures the temporal pattern of CO2 concentrations at the ground site at the California Institute of Technology in Pasadena, but it overestimates the magnitude in early daytime. Analysis of CO2 by wind directions reveals the overestimate is due to advection from the south and southwest, where downtown Los Angeles is located. The model also captures the vertical profile of CO2 concentrations along with the flight tracks. The optimized VPRM parameters have significantly improved simulated net ecosystem exchange at each vegetation-class site and thus the regional CO2 budget. The total biospheric contribution ranges approximately from −24% to −20% (daytime) of the total anthropogenic CO2 emissions during the study period.

Water Splitting: Unexpected Fe(VI) Trapped by Manipulation of Reaction Kinetics

Recently in Joule, Gray and co-workers have reported a pivotal and fully unexpected role of a very-high-valent Fe(VI) intermediate in water oxidation by NiFe oxyhydroxides.

An Experimental Scattering Matrix for Lunar Regolith Simulant JSC-1A at Visible Wavelengths

The contributions of co-authors J.D. Goguen and R.A. West were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We are indebted to Rocio Marquez from the Scientific Instrumentation center of the University of Granada for providing part of the SEM images. This work has been supported by the Plan Nacional de Astronomia y Astrofisica contracts AYA2015-67152-R and AYA2015-71975-REDT.

Photoelectrochemical Performance of BiVO4 Photoanodes Integrated with [NiFe]‐Layered Double Hydroxide Nanocatalysts

AbstractInvited for the cover of this issue are AstridàM. Müller and co‐workers from California Institute of Technology, Pasadena, California, USA. The cover image shows a drawing of an integrated photoanode whose active materials are laser‐synthesized highly efficient [NiFe]‐layered double hydroxide or Co3O4 water oxidation nanocatalysts and sunlight‐absorbing BiVO4.

INVITED EDITORIAL COMMENT

1. Bradford Cornell 1. is a professor of finance at the California Institute of Technology and managing director at SMBP LLC in Pasadena, CA . (bcornell{at}caltech.edu) I wear two hats. For 40 years, I have been a professor of finance. For the last 10 years, I have run a small hedge fund. In

Irving Langmuir Award in Chemical Physics: George W. Flynn

Sponsor: ACS and the ACS Division of Physical Chemistry Citation: For contributions to our fundamental understanding of the structural and chemical behavior of graphene interfaces. Current position: Eugene Higgins Professor of Chemistry, Columbia University Education: B.S., chemistry, Yale University; Ph.D., chemistry, Harvard University Flynn on his scientific role model and why: “Four mentors have had a significant influence in determining the course of my scientific career: my high school chemistry teacher, Mr. Coburn, who made chemistry a remarkably clear discipline and introduced me to independent research; Ali Javan, who taught me to think like a physicist about the interaction of light and matter; and John Baldeschwieler and E. Bright Wilson, who were my Ph.D. mentors and taught me the importance of clear thinking in scientific discussions and about being fearless in attacking new research areas.” What his colleagues say: “In groundbreaking work, he demonstrated that single sheet graphenes are much more reactive than multiple sheet materials. His fundamental work will surely be of great help to investigators who are working on electronic devices based on graphene and doped-graphene materials.”—Harry B. Gray, California Institute of Technology.