17 research outputs found
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
Sharing and community curation of mass spectrometry data with Global Natural Products Social Molecular Networking
The potential of the diverse chemistries present in natural products (NP) for biotechnology and medicine remains untapped because NP databases are not searchable with raw data and the NP community has no way to share data other than in published papers. Although mass spectrometry techniques are well-suited to high-throughput characterization of natural products, there is a pressing need for an infrastructure to enable sharing and curation of data. We present Global Natural Products Social molecular networking (GNPS, http://gnps.ucsd.edu), an open-access knowledge base for community wide organization and sharing of raw, processed or identified tandem mass (MS/MS) spectrometry data. In GNPS crowdsourced curation of freely available community-wide reference MS libraries will underpin improved annotations. Data-driven social-networking should facilitate identification of spectra and foster collaborations. We also introduce the concept of ‘living data’ through continuous reanalysis of deposited data
Mapping Molecular Space with Mass Spectrometry /
Mass spectrometry has become an invaluable tool in the discovery and characterization of specialized metabolites and biotechnologically relevant molecules. One aspect of characterizing specialized metabolites involves connecting these molecules to their biosynthetic machineries. Here we employ several mass spectrometry methods and introduce the idea of connecting molecular families to their gene cluster families on a large scale that takes advantage of publicly accessible genomes. As proof of principle, we used molecular networking to analyze sixty bacteria, 42 bacilli and 18 pseudomonads, simultaneously and matched eight molecular families to their gene cluster families. To illustrate the effectiveness of this technique, we combined it with imaging mass spectrometry to examine two marine Pseudoalteromonas that both showed inhibition against Bacillus subtilis 3610. The signals showing bioactivity against B. subtilis were shown to be a family of molecules for which the biosynthetic gene cluster was discovered using a publiclyavailable genome sequence from Pseudoalteromonas piscicida JCM 20779
Applications in Mass Spectrometry and Molecular Networking: The Pseudomonas Specialized Metabolome and Algal Biofuels
In 1886, physicist Eugen Goldstein discovered Kanalstrahlen or "canal rays," rays that moved from anode to cathode and determined that these rays were composed of positively charged particles. Twelve years later, another physicist named Wilhelm Wien demonstrated that canal rays, in the presence of strong electric and magnetic fields, could be deflected and that different rays travel different parabolic paths depending on their charge-to-mass ratios. It was at this time that the first mass spectrometers were born. Fast forward to present day, we now have numerous ways to generate ions, a variety of mass analyzers, and seemingly limitless applications for mass spectrometry---mass spectrometers are even being sent to Mars! To make a long story short, modern mass spectrometers have come a very, very long way from their ancestors in the late 1800’s. Mass specs are faster, more sensitive, and capable of more advanced analysis than ever before, however, the difficult problem of molecular identification still remains in the field of natural products and metabolomics. Chemistries produced by the natural world are complex messes of complicated molecular structures and biochemical transformations that always make understanding the world a difficult task. The work presented in this dissertation are applications of mass spectrometry and molecular networking, which are only small steps in the direction of simplifying molecular identification. The chemical repertoire of hundreds bacteria belonging to the same genus are explored, four new molecules are discovered, and a reference index of compounds has been created to aid future studies of the bacterial genus Pseudomonas. Lastly, this dissertation applies mass spectrometry and molecular networking in an attempt to deconvolute the metabolic exchange factors that take place in predator-prey interactions. It appears that the predator leaves specific signatures belonging to breakdown products of a key molecule involved in photosynthesis---a signature that could be used for crop protection in the production of alternative liquid fuels
Energy storage systems in distributed generation schemes
An overview is given of the various energy storage technologies which can be used in distributed generation (DG) schemes. Description of the recent photovoltaic DG initiative in Singapore is included, in which several of the storage systems can find ready applications. Schemes pertaining to the use of solid oxide fuel cell for power quality enhancement and battery energy storage system used in conjunction with wind power generation are also described
Modeling and position-sensorless control of a dual-airgap axial flux permanent magnet machine for flywheel energy storage systems
This paper presents the modeling and position-sensorless vector control of a dual-airgap axial flux permanent magnet (AFPM) machine optimized for use in flywheel energy storage system (FESS) applications. The proposed AFPM machine has two sets of three-phase stator windings but requires only a single power converter to control both the electromagnetic torque and the axial levitation force. The proper controllability of the latter is crucial as it can be utilized to minimize the vertical bearing stress to improve the efficiency of the FESS. The method for controlling both the speed and axial displacement of the machine is discussed. An inherent speed sensorless observer is also proposed for speed estimation. The proposed observer eliminates the rotary encoder, which in turn reduces the overall weight and cost of the system while improving its reliability. The effectiveness of the proposed control scheme has been verified by simulations and experiments on a prototype machine
Effect of annealing temperature on structural and electrical properties of tantalum nitride thin film resistors deposited on SiO[sub 2]∕Si substrates by dc sputtering technique
Effect of film thickness on the electrical properties of tantalum nitride thin films deposited on SiO[sub 2]∕Si substrates for Π-type attenuator applications
Anaemia in schoolchildren in eight countries in Africa and Asia.
OBJECTIVE: To report on the haemoglobin concentrations and prevalence of anaemia in schoolchildren in eight countries in Africa and Asia. DESIGN: Blood samples were collected during surveys of the health of schoolchildren as a part of programmes to develop school-based health services. SETTING: Rural schools in Ghana, Indonesia, Kenya, Malawi, Mali, Mozambique, Tanzania and Vietnam. SUBJECTS: Nearly 14 000 children enrolled in basic education in three age ranges (7-11 years, 12-14 years and > or =15 years) which reflect the new UNICEF/WHO thresholds to define anaemia. RESULTS: Anaemia was found to be a severe public health problem (defined as >40% anaemic) in five African countries for children aged 7-11 years and in four of the same countries for children aged 12-14 years. Anaemia was not a public health problem in the children studied in the two Asian countries. More boys than girls were anaemic, and children who enrolled late in school were more likely to be anaemic than children who enrolled closer to the correct age. The implications of the four new thresholds defining anaemia for school-age children are examined. CONCLUSIONS: Anaemia is a significant problem in schoolchildren in sub-Saharan Africa. School-based health services which provide treatments for simple conditions that cause blood loss, such as worms, followed by multiple micronutrient supplements including iron, have the potential to provide relief from a large burden of anaemia
Eclipsing Binary Science via the Merging of Transit and Doppler Exoplanet Survey Data—A Case Study with the MARVELS Pilot Project and SuperWASP
Exoplanet transit and Doppler surveys discover many binary stars during their
operation that can be used to conduct a variety of ancillary science.
Specifically, eclipsing binary stars can be used to study the stellar
mass-radius relationship and to test predictions of theoretical stellar
evolution models. By cross-referencing 24 binary stars found in the MARVELS
Pilot Project with SuperWASP photometry, we find two new eclipsing binaries,
TYC 0272-00458-1 and TYC 1422-01328-1, which we use as case studies to develop
a general approach to eclipsing binaries in survey data. TYC 0272-00458-1 is a
single-lined spectroscopic binary for which we calculate a mass of the
secondary and radii for both components using reasonable constraints on the
primary mass through several different techniques. For a primary mass of M_1 =
0.92 +/- 0.1 M_solar, we find M_2 = 0.610 +/- 0.036 M_solar, R_1 = 0.932 +/-
0.076 R_solar and R_2 = 0.559 +/- 0.102 R_solar, and find that both stars have
masses and radii consistent with model predictions. TYC 1422-01328-1 is a
triple-component system for which we can directly measure the masses and radii
of the eclipsing pair. We find that the eclipsing pair consists of an evolved
primary star (M_1 = 1.163 +/- 0.034 M_solar, R_1 = 2.063 +/- 0.058 R_solar) and
a G-type dwarf secondary (M_2 = 0.905 +/- 0.067 M_solar, R_2 = 0.887 +/- 0.037
R_solar). We provide the framework necessary to apply this analysis to much
larger datasets.Comment: Accepted for publication in A