Large ionospheric disturbances produced by the HAARP HF facility

NASA Astrophysics Data System (ADS)

Bernhardt, Paul A.; Siefring, Carl L.; Briczinski, Stanley J.; McCarrick, Mike; Michell, Robert G.

2016-07-01

The enormous transmitter power, fully programmable antenna array, and agile frequency generation of the High Frequency Active Auroral Research Program (HAARP) facility in Alaska have allowed the production of unprecedented disturbances in the ionosphere. Using both pencil beams and conical (or twisted) beam transmissions, artificial ionization clouds have been generated near the second, third, fourth, and sixth harmonics of the electron gyrofrequency. The conical beam has been used to sustain these clouds for up to 5 h as opposed to less than 30 min durations produced using pencil beams. The largest density plasma clouds have been produced at the highest harmonic transmissions. Satellite radio transmissions at 253 MHz from the National Research Laboratory TACSat4 communications experiment have been severely disturbed by propagating through artificial plasma regions. The scintillation levels for UHF waves passing through artificial ionization clouds from HAARP are typically 16 dB. This is much larger than previously reported scintillations at other HF facilities which have been limited to 3 dB or less. The goals of future HAARP experiments should be to build on these discoveries to sustain plasma densities larger than that of the background ionosphere for use as ionospheric reflectors of radio signals.

Methods for Creation and Detection of Ultra-Strong Artificial Ionization in the Upper Atmosphere (Invited)

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Siefring, C. L.; Briczinski, S. J.; Kendall, E. A.; Watkins, B. J.; Bristow, W. A.; Michell, R.

2013-12-01

The High Frequency Active Auroral Research Program (HAARP) transmitter in Alaska has been used to produce localized regions of artificial ionization at altitudes between 150 and 250 km. High power radio waves tuned near harmonics of the electron gyro frequency were discovered by Todd Pederson of the Air Force Research Laboratory to produce ionosonde traces that looked like artificial ionization layers below the natural F-region. The initial regions of artificial ionization (AI) were not stable but had moved down in altitude over a period of 15 minutes. Recently, artificial ionization has been produced by the 2nd, 3rd, 4th and 6th harmonics transmissions by the HAARP. In march 2013, the artificial ionization clouds were sustained for more the 5 hours using HAARP tuned to the 4 fce at the full power of 3.6 Mega-Watts with a twisted-beam antenna pattern. Frequency selection with narrow-band sweeps and antenna pattern shaping has been employed for optimal generation of AI. Recent research at HAARP has produced the longest lived and denser artificial ionization clouds using HF transmissions at the harmonics of the electron cyclotron frequency and ring-shaped radio beams tailored to prevent the descent of the clouds. Detection of artificial ionization employs (1) ionosonde echoes, (2) coherent backscatter from the Kodiak SuperDARN radar, (3) enhanced ion and plasma line echoes from the HAARP MUIR radar at 400 MHz, (4) high resolution optical image from ground sites, and (5) unique stimulated electromagnetic emissions, and (6) strong UHF and L-Band scintillation induced into trans-ionospheric signals from satellite radio beacons. Future HAARP experiments will determine the uses of long-sustained AI for enhanced HF communications.

Physics of the Geospace Response to Powerful HF Radio Waves

DTIC Science & Technology

2012-10-31

studies of the response of the Earth’s space plasma to high-power HF radio waves from the High-frequency Active Auroral Research Program ( HAARP ...of HF heating and explored to simulate artificial ducts. DMSP- HAARP experiments revealed that HF-created ion outflows and artificial density ducts...in the topside ionosphere appeared faster than predicted by the models, pointing to kinetic (suprathermal) effects. CHAMP/GRACE- HAARP experiments

Interharmonic modulation products as a means to quantify nonlinear D-region interactions

NASA Astrophysics Data System (ADS)

Moore, Robert

Experimental observations performed during dual beam ionospheric HF heating experiments at the High frequency Active Auroral Research Program (HAARP) HF transmitter in Gakona, Alaska are used to quantify the relative importance of specific nonlinear interactions that occur within the D region ionosphere. During these experiments, HAARP broadcast two amplitude modulated HF beams whose center frequencies were separated by less than 20 kHz. One beam was sinusoidally modulated at 500 Hz while the second beam was sinusoidally modulated using a 1-7 kHz linear frequency-time chirp. ELF/VLF observations performed at two different locations (3 and 98 km from HAARP) provide clear evidence of strong interactions between all field components of the two HF beams in the form of low and high order interharmonic modulation products. From a theoretical standpoint, the observed interharmonic modulation products could be produced by several different nonlinearities. The two primary nonlinearities take the form of wave-medium interactions (i.e., cross modulation), wherein the ionospheric conductivity modulation produced by one signal crosses onto the other signal via collision frequency modification, and wave-wave interactions, wherein the conduction current associated with one wave mixes with the electric field of the other wave to produce electron temperature oscillations. We are able to separate and quantify these two different nonlinearities, and we conclude that the wave-wave interactions dominate the wave-medium interactions by a factor of two. These results are of great importance for the modeling of transioinospheric radio wave propagation, in that both the wave-wave and the wave-medium interactions could be responsible for a significant amount of anomalous absorption.

Geophysical Remote Sensing Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines Produced by HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Selcher, C. A.

2009-12-01

An ordinary or extraordinary mode electromagnetic wave can decay into a low frequency electrostatic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The low frequency wave can be either an ion acoustic wave (IA) or an electrostatic ion cyclotron (EIC) wave. The first detection ion acoustic waves by this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. The first detection of the electrostatic ion cyclotron waves is reported here using HAARP during the March 2009 campaign. Subsequent experiments have provided additional verification of the SBS process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere by Bernhardt et al. (2009). Using the SBS technique to generate ion acoustic waves, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave can produced by the generalized SBS processes only if the pump waves makes a large angle with the magnetic field. When the EIC mode is produced, it is seen as a narrow of stimulated electromagnetic emissions at the ion cyclotron frequency. Occasionally, multiple lines are seen and analyzed to yield the relative abundance of oxygen, and molecular ions in the lower ionosphere. This ion mass spectrometer interpretation of the SBS data is new to the field of ionosphere remote sensing. In addition, based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values. All of these measurements of the HF modified ionosphere are made possible at HAARP because of (1) the recently increased transmitter power to 3.6 MW into the large antenna array and (2) the new digital receiver diagnostics that allow up to 100 dB dynamic range in the stimulated electromagnetic emission measurements. Paul A. Bernhardt, Craig A. Selcher, Robert H. Lehmberg, Serafin Rodriguez, Joe Thomason, Mike McCarrick, Gordon Frazer, Determination of the Electron Temperature in the Modified Ionosphere over HAARP Using the HF Pumped Stimulated Brillouin Scatter (SBS) Emission Lines, Annales Geophysicae, in press, 2009. Norin, L., Leyser, T. B., Nordblad, E., Thidé, B., and McCarrick, M., Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere, Phys. Rev. Lett., 102, 065003, 2009.

Electron Acceleration and Ionization Production in High-Power Heating Experiments at HAARP

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Pedersen, T.

2012-12-01

Recent ionospheric modification experiments with the 3.6 MW transmitter at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska led to discovery of artificial ionization descending from the nominal interaction altitude in the background F-region ionosphere by ~60-80 km. Artificial ionization production is indicated by significant 427.8 nm emissions from the 1st negative band of N2+ and the appearance of transmitter-induced bottomside traces in ionosonde data during the periods of most intense optical emissions. However, the exact mechanisms producing the artificial plasmas remain to be determined. Yet the only existing theoretical models explain the development of artificial plasma as an ionizing wavefront moving downward due to ionization by electrons accelerated by HF-excited strong Langmuir turbulence (SLT) generated near the plasma resonance, where the pump frequency matches the plasma frequency. However, the observations suggest also the significance of interactions with upper hybrid and electron Bernstein waves near multiples of the electron gyrofrequency. We describe recent observations and discuss suitable acceleration mechanisms.

Studies of the Ionospheric Turbulence Excited by the Fourth Gyroharmonic at HAARP

NASA Astrophysics Data System (ADS)

Milikh, G. M.; Najmi, A. C.; Mahmoudian, A.; Bernhardt, P. A.; Briczinski, S.; Siefring, C. L.; Yampolski, Y.; Alexander, K.; Sopin, A.; Zalizovski, A.; Chiang, K.; Psiaki, M. L.; Morton, Y.; Taylor, S.; Papadopoulos, K.

2014-12-01

We report the results of a set of experiments conducted during the HAARP June 2014 campaign, whose objective was to study the development of artificial ionospheric turbulence. During the experiments, the heating frequency was stepped up and down near the 4th gyroharmonic, and the power of the heating HF radiation was varied. Our diagnostics included: measurements of phase-derived Slant Total Electron Content using the L1/L2 signals from PRN 25 GPS satellite received at HAARP; measurements of Stimulated Electromagnetic Emission (SEE) conducted 15 km away from the HAARP site; detection of the HAARP HF radiation at Vernadsky station located in Antarctica ~15.6 Mm from HAARP; ionograms from HAARP's digisonde and reflectance data from Kodiak radar. Our observations showed: a distinct correlation between the broad upshifted maximum detected by the SEE and strong suppression of the HF signals detected at Vernadsky station; drift velocity of the ionospheric irregularities causing HF scattering detected at Vernadsky station corresponds to that measured by the Kodiak radar; the intensity of the scattered radar signals by Kodiak correlates with the amplitude of downshifted maximum observed by the SEE.

ELF/VLF Wave Generation via HF Modulation of the Equatorial Electrojet at Arecibo Observatory

NASA Astrophysics Data System (ADS)

Flint, Q. A.; Moore, R. C.; Burch, H.; Erdman, A.; Wilkes, R.

2017-12-01

In this work we generate ELF/VLF waves by modulating the conductivity of the lower ionosphere using the HF heater at Arecibo. For many years, researchers have generated ELF/VLF waves using the powerful HF transmitters at HAARP, but few have attempted to do the same in the mid- to low- latitude region. While HAARP users have benefitted from the auroral electrojet, we attempt to exploit the equatorial electrojet to generate radio waves. On 31 July 2017, we transmitted at an HF frequency of 5.1 MHz (X-Mode) applying sinusoidal amplitude modulation in a step-like fashion from 0-5 kHz in 200 Hz steps over 10 seconds at 100% peak power to approximate a linear frequency ramp. We also transmitted 10-second-long fixed frequency tones spaced from 1 to 5 kHz. The frequency sweep is a helpful visual tool to identify generated waves, but is also used to determine optimal modulation frequencies for future campaigns. The tones allow us to perform higher SNR analysis. Ground-based B-field VLF receivers recorded the amplitude and phase of the generated radio waves. We employ time-of-arrival techniques to determine the altitude of the ELF/VLF signal source. In this paper, we present the initial analysis of these experimental results.

Upper Atmospheric Effects of the HF Active Auroral Research Program Ionospheric Research Instrument (HAARP IRI)

DTIC Science & Technology

1993-05-01

RESEARCH INSTRUMENT ( HAARP IRI) V. Eccles R. Armstrong Mission Research Corporation One Tara Blvd Nashua, NH 03062-2801 May 1993 Scientific Report No...INSTRUMENT ( HAARP IRI) PR 2310 STA G3 WU BM6. AUTHOR(S) V. Eccles and R. Armstrong 7. PERFOR•IlNG ORGANIZATION NAME(S) AND AOORESS(ES) 8. PERFORMING...Because the HAARP (HF Active Auroral Research Program) facility is designed to mimic and investigate certain natural processes, a study of possible

Low-Frequency Waves in HF Heating of the Ionosphere

NASA Astrophysics Data System (ADS)

Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

2016-02-01

Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

Generation of whistler waves by continuous HF heating of the upper ionosphere

NASA Astrophysics Data System (ADS)

Vartanyan, A.; Milikh, G. M.; Eliasson, B.; Najmi, A. C.; Parrot, M.; Papadopoulos, K.

2016-07-01

Broadband VLF waves in the frequency range 7-10 kkHz and 15-19 kHz, generated by F region CW HF ionospheric heating in the absence of electrojet currents, were detected by the DEMETER satellite overflying the High Frequency Active Auroral Research Program (HAARP) transmitter during HAARP/BRIOCHE campaigns. The VLF waves are in a frequency range corresponding to the F region lower lybrid (LH) frequency and its harmonic. This paper aims to show that the VLF observations are whistler waves generated by mode conversion of LH waves that were parametrically excited by HF-pump-plasma interaction at the upper hybrid layer. The paper discusses the basic physics and presents a model that conjectures (1) the VLF waves observed at the LH frequency are due to the interaction of the LH waves with meter-scale field-aligned striations—generating whistler waves near the LH frequency; and (2) the VLF waves at twice the LH frequency are due to the interaction of two counterpropagating LH waves—generating whistler waves near the LH frequency harmonic. The model is supported by numerical simulations that show good agreement with the observations. The (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions results and model discussions are complemented by the Kodiak radar, ionograms, and stimulated electromagnetic emission observations.

Upper atmospheric effects of the hf active auroral research program ionospheric research instrument (HAARP IRI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eccles, V.; Armstrong, R.

1993-05-01

The earth's ozone layer occurs in the stratosphere, primarily between 10 and 30 miles altitude. The amount of ozone, O3, present is the result of a balance between production and destruction processes. Experiments have shown that natural processes such as auroras create molecules that destroy O. One family of such molecules is called odd nitrogen of which nitric oxide (NO) is an example. Because the HAARP (HF Active Auroral Research Program) facility is designed to mimic and investigate certain natural processes, a study of possible effects of HAARP on the ozone layer was conducted. The study used a detailed modelmore » of the thermal and chemical effects of the high power HF beam, which interacts with free electrons in the upper atmosphere above 50 miles altitude. It was found only a small fraction of the beam energy goes into the production of odd nitrogen molecules, whereas odd nitrogen is efficiently produced by auroras. Since the total energy emitted by HAARP in the year is some 200,000 times less than the energy deposited in the upper atmosphere by auroras, the study demonstrates that HAARP HF beam experiments will cause no measurable depletion of the earth's ozone layer.... Ozone, Ozone depletion, Ozone layer, Odd nitrogen, Nitric oxide, HAARP Emitter characteristics.« less

A Diagnostic System for Studying Energy Partitioning and Assessing the Response of the Ionosphere during HAARP Modification Experiments

NASA Technical Reports Server (NTRS)

Djuth, Frank T.; Elder, John H.; Williams, Kenneth L.

1996-01-01

This research program focused on the construction of several key radio wave diagnostics in support of the HF Active Auroral Ionospheric Research Program (HAARP). Project activities led to the design, development, and fabrication of a variety of hardware units and to the development of several menu-driven software packages for data acquisition and analysis. The principal instrumentation includes an HF (28 MHz) radar system, a VHF (50 MHz) radar system, and a high-speed radar processor consisting of three separable processing units. The processor system supports the HF and VHF radars and is capable of acquiring very detailed data with large incoherent scatter radars. In addition, a tunable HF receiver system having high dynamic range was developed primarily for measurements of stimulated electromagnetic emissions (SEE). A separate processor unit was constructed for the SEE receiver. Finally, a large amount of support instrumentation was developed to accommodate complex field experiments. Overall, the HAARP diagnostics are powerful tools for studying diverse ionospheric modification phenomena. They are also flexible enough to support a host of other missions beyond the scope of HAARP. Many new research programs have been initiated by applying the HAARP diagnostics to studies of natural atmospheric processes.

Power-Stepped HF Cross Modulation Experiments at HAARP

NASA Astrophysics Data System (ADS)

Greene, S.; Moore, R. C.; Langston, J. S.

2013-12-01

High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. In this paper, we apply experimental observations of HF cross-modulation to the related problem of ELF/VLF wave generation. HF cross-modulation measurements are used to evaluate the efficiency of ionospheric conductivity modulation during power-stepped modulated HF heating experiments. The results are compared to previously published dependencies of ELF/VLF wave amplitude on HF peak power. The experiments were performed during the March 2013 campaign at the High Frequency Active Auroral Research Program (HAARP) Observatory. HAARP was operated in a dual-beam transmission format: the first beam heated the ionosphere using sinusoidal amplitude modulation while the second beam broadcast a series of low-power probe pulses. The peak power of the modulating beam was incremented in 1-dB steps. We compare the minimum and maximum cross-modulation effect and the amplitude of the resulting cross-modulation waveform to the expected power-law dependence of ELF/VLF wave amplitude on HF power.

Future Operations of HAARP with the UAF's Geophysical Institute

NASA Astrophysics Data System (ADS)

McCoy, R. P.

2015-12-01

The High frequency Active Aurora Research Program (HAARP) in Gakona Alaska is the world's premier facility for active experimentation in the ionosphere and upper atmosphere. The ionosphere affects communication, navigation, radar and a variety of other systems depending on, or affected by, radio propagation through this region. The primary component of HAARP, the Ionospheric Research Instrument (IRI), is a phased array of 180 HF antennas spread across 33 acres and capable of radiating 3.6 MW into the upper atmosphere and ionosphere. The array is fed by five 2500 kW generators, each driven by a 3600 hp diesel engine (4 + 1 spare). Transmit frequencies are selectable in the range 2.8 to 10 MHz and complex configurations of rapidly slewed single or multiple beams are possible. HAARP was owned by the Air Force Research Laboratory (AFRL/RV) in Albuquerque, NM but recently was transferred to the Geophysical Institute of the University of Alaska Fairbanks (UAF/GI). The transfer of ownership of the facility is being implemented in stages involving a Cooperative Research and Development Agreement (CRADA) and an Educational Partnership Agreement (EPA) which are complete, and future agreements to transfer ownership of the facility land. The UAF/GI plans to operate the facility for continued ionospheric and upper atmospheric experimentation in a pay-per-use model. In their 2013 "Decadal Survey in Solar and Space Physics" the National Research Council (NRC) made the recommendation to "Fully realize the potential of ionospheric modification…" and in their 2013 Workshop Report: "Opportunities for High-Power, High-Frequency Transmitters to Advance Ionospheric/Thermospheric Research" the NRC outlined the broad range of future ionospheric, thermospheric and magnetospheric experiments that could be performed with HAARP. HAARP is contains a variety of RF and optical ionospheric diagnostic instruments to measure the effects of the heater in real time. The UAF/GI encourages the scientific community to plan experiments at HAARP and bring their remote sensing instruments to HAARP for extended or permanent operation. The power and flexibility of HAARP and its unique location in the subarctic will help secure the future of this facility as the foremost laboratory for active experimentation in the ionosphere and upper atmosphere.

High Frequency Radar Astronomy With HAARP

DTIC Science & Technology

2003-01-01

High Frequency Radar Astronomy With HAARP Paul Rodriguez Naval Research Laboratory Information Technology Division Washington, DC 20375, USA Edward...a period of several years, the High frequency Active Auroral Research Program ( HAARP ) transmitting array near Gakona, Alaska, has increased in total...high frequency (HF) radar facility used for research purposes. The basic science objective of HAARP is to study nonlinear effects associated with

The WIND-HAARP Experiment: Initial Results of High Power Radiowave Interactions with Space Plasmas

DTIC Science & Technology

1997-11-10

Results from the first science experiment with the new HF Active Auroral Research Program ( HAARP ) facility in Alaska are reported. The initial...experiments involved transmission of high frequency waves from HAARP to the NASA/WIND satellite. The objective was to investigate the effects of space

Initial Results from CASSIOPE/ePOP Satellite Overpasses above HAARP in 2014

NASA Astrophysics Data System (ADS)

Siefring, C. L.; Bernhardt, P. A.; Briczinski, S. J., Jr.; James, H. G.; Yau, A. W.; Knudsen, D. J.

2015-12-01

The High Frequency Active Auroral Research Program (HAARP) facility was operated in conjunction with overpasses of the enhanced Polar Outflow Probe (ePOP) instruments on the Canadian CASSIOPE satellite. During these overpasses HAARP was operated in several different heating modes and regimes as diagnosed by the characteristics of Stimulated Electromagnetic Emissions (SEE) using ground-based receivers while simultaneously ePOP monitored in-situ HF and VLF signals, looked for ion and electron heating, and provided VHF and UHF signals for propagation effects studies. The e-POP suite of instruments and particularly the ePOP Radio Receiver Instrument (RRI) offer a unique combination diagnostics appropriate for studying the non-linear plasma effects generated high-power HF waves in the ionosphere. In this presentation, the initial results from ePOP observations from two separate 2014 measurement campaigns at HAARP (April 16 to April 29 and May 25 to June 9) will be discussed. Several innovative experiments were performed during the campaign. Experiments explored a wide range of ionospheric effects. These include: 1) Penetration of HF pump waves into the ionosphere via large and small scale irregularities, 2) effects of gyro-harmonic heating and artificial ionization layers, 3) effects of HAARP beam shape with O- and X-mode transmissions, 4) coupling of Lower Hybrid modes into Whistler waves, 5) D/E-region VLF generation in the ionosphere using VLF modulation of the HF pump 6) scattering of VHF and UHF signals and 7) scattering and non-linear modulation of a 9.5 MHz probe wave propagating through the region of the ionosphere modified by HAARP. This work supported by the Naval Research Laboratory Base Program.

Geophysical Electromagnetic Sounding Using HAARP

DTIC Science & Technology

2002-03-01

apparent resistivity vs. frequency can be converted into true resistivity vs. depth, This grant involved an investigation into the HAARP virtual antenna pattern out to 200 km, and its use as a CSAMT transmitter.

Artificial Aurora and Ionospheric Heating by HAARP

NASA Astrophysics Data System (ADS)

Hadavandkhani, S.; Nikouravan, Bijan; Ghazimaghrebi, F.

2016-08-01

A recent experiment was achieved at HAARP to study the scaling of the ionospherically generated ELF signal with power transmitted from the high frequency (HF) array. The results were in excellent agreement with computer simulations. The outcomes approving that the ELF power increases with the square of the incident HF power. This paper present a review on the situation of the ionized particles in Ionospheric layer when stimulated by artificial an ELF and VLF external high energy radio waves.

Imaging and Forecasting of Ionospheric Structures and Their System Impacts

DTIC Science & Technology

2003-12-05

Trapped electrons, Wave/particle interaction, Plasmasphere, Magnetic field, HAARP , Cal/Val 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 18. NUMBER 19a...support to the HAARP digisonde (DPS) over the past year, UMLCAR cooperated with AFRL on a campaign during the last week of August 2003. This campaign was...held to develop new diagnostic techniques using the HAARP transmitter, the digisonde, and the all-sky imager as part of a coordinated measurement

Basis of Ionospheric Modification by High-Frequency Waves

DTIC Science & Technology

2007-06-01

for conducting ionospheric heating experiments in Gakona, Alaska, as part of the High Frequency Active Auroral Research Program ( HAARP ) [5], is being...upgraded. The upgraded HAARP HF transmitting system will be a phased-array antenna of 180 elements. Each element is a cross dipole, which radiates a...supported by the High Frequency Active Auroral Research Program ( HAARP ), the Air Force Research Laboratory at Hanscom Air Force Base, MA, and by the Office

Studies of Plasma Instabilities Excited by Ground-Based High Power HF (Heating) Facilities and of X and Gamma Ray Emission in Runaway Breakdown Processes

DTIC Science & Technology

2006-08-01

latitude ( HAARP , TROMSO) and mid latitude (SURA) facilities [1]. The very strong and fully reproducible plasma perturbations in ionosphere are observed...beam propagating along magnetic field (θ = 0), in this case factor κs ≈ 1. As an a example we will consider now the HAARP facility. The ERP for HAARP ...as a function of fre- quency f0 is presented in the Table 1. ISTC 2236p 12 Table 1 ERP as function of wave frequency for HAARP (2001) f0 (MHz

Shear Alfven Wave Injection in the Magnetosphere by Ionospheric Modifications in the Absence of Electrojet Currents

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Eliasson, B.; Shao, X.; Labenski, J.; Chang, C.

2011-12-01

A new concept of generating ionospheric currents in the ULF/ELF range with modulated HF heating using ground-based transmitters even in the absence of electrojet currents is presented. The new concept relies on using HF heating of the F-region to modulate the electron temperature and has been given the name Ionospheric Current Drive (ICD). In ICD, the pressure gradient associated with anomalous or collisional F-region electron heating drives a local diamagnetic current that acts as an antenna to inject mainly Magneto-Sonic (MS) waves in the ionospheric plasma. The electric field associated with the MS wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that inject waves in the Earth-Ionosphere Waveguide (EIW) below and shear Alfven waves or EMIC waves upwards towards the conjugate regions. The paper presents: (i) Theoretical results using a cold Hall MHD model to study ICD and the generation of ULF/ELF waves by the modulation of the electron pressure at the F2-region with an intense HF electromagnetic wave. The model solves equations governing the dynamics of the shear Alfven and magnetosonic modes, of the damped modes in the diffusive Pedersen layer, and of the weakly damped helicon wave mode in the Hall-dominated E-region. The model incorporates realistic profile of the ionospheric conductivities and magnetic field configuration. We use the model to simulate propagation and dynamics of the low-frequency waves and their injection into the magnetosphere from the HAARP and Arecibo ionospheric heaters. (ii) Proof of principle experiments using the HAARP ionospheric heater in conjunction with measurements by the DEMETER satellite This work is supported by ONR MURI grant and DARPA BRIOCHE Program

ELF/VLF Wave Generation and Scattering from Modulated Heating of the Ionosphere at Arecibo Observatory

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; McCormick, J.; Cohen, M.; Hosseini, P.; Bittle, J.

2017-12-01

The recently completed ionospheric heater at Arecibo Observatory is used for modulated HF (5 or 8 MHz) heating of the ionosphere, to generate ELF/VLF (3 Hz - 30 kHz) waves. Observation of ramp and tone signals at frequencies from hundreds of Hz to several kHz at multiple receivers confirms the ability of the heater to modulate D region currents and create an ELF/VLF antenna in the ionosphere. Observed ELF/VLF signal amplitudes are lower than for similar experiments performed at high latitudes at the HAARP and Tromso facilities, for a variety of reasons including the reduced natural currents at mid latitudes, and the lower HF power of the Arecibo heater. The heating of the overhead ionosphere is also observed to change the Earth-ionosphere waveguide propagation characteristics as is evident from simultaneous observations of lightning induced sferics and VLF transmitter signals that propagate under the heated region. The active heating of the ionosphere modifies the reflection of incident VLF (3-30 kHz) waves. We present initial observations of HF heating of the D-region and resulting ELF/VLF wave generation.

High Power HF Excitation of Low Frequency Stimulated Electrostatic Waves in the Ionospheric Plasma over HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, Paul; Selcher, Craig A.

High Power electromagnetic (EM) waves transmitted from the HAARP facility in Alaska can excite low frequency electrostatic waves by several processes including (1) direct magnetized stimulated Brillouin scatter (MSBS) and (2) parametric decay of high frequency electrostatic waves into electron and ion Bernstein waves. Either an ion acoustic (IA) wave with a frequency less than the ion cyclotron frequency (fCI) or an electrostatic ion cyclotron (EIC) wave just above fCI can be produced by MSBS. The coupled equations describing the MSBS instabil-ity show that the production of both IA and EIC waves is strongly influenced by the wave propagation direction relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions (SEE) using the HAARP transmitter in Alaska have confirmed the theoretical predictions that only IA waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The electron temperature in the heated plasma is obtained from the IA spectrum offsets from the pump frequency. The ion composition can be determined from the measured EIC frequency. Near the second harmonic of the electron cyclotron frequency, the EM pump wave is converted into an electron Bernstein (EB) wave that decays into another EB wave and an ion Bernstein (IB) wave. Strong cyclotron resonance with the EB wave leads to acceleration of the electrons. Ground based SEE observations are related to the theory of low-frequency electrostatic wave generation.

Studies of Plasma Instability Processes Excited by Ground Based High Power HF (Heating) Facilities

DTIC Science & Technology

2001-04-01

and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility (Peterson...Haslett and Megill, 1974; Carlson, 1974; Bernhardt et al., 1989). During the last years new interesting results have been obtained at HAARP facility

HAARP-Induced Ionospheric Ducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milikh, Gennady; Vartanyan, Aram

2011-01-04

It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Thosemore » observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.« less

Mid-latitude Narrowband Stimulated Electromagnetic Emissions (NSEE): New Observations and Modeling

NASA Astrophysics Data System (ADS)

Nossa, E.; Mahmoudian, A.; Isham, B.; Bernhardt, P. A.; Briczinski, S. J., Jr.

2017-12-01

High power electromagnetic waves (EM) transmitted from the ground interact with the local plasma in the ionosphere and can produce Stimulated Electromagnetic Emissions (SEE) through the parametric decay instability (PDI). The classical SEE features known as wideband SEE (WSEE) with frequency offset of 1 kHz up to 100 kHz have been observed and studied in detail in the 1980s and 1990s. A new era of ionospheric remote sensing techniques was begun after the recent update of the HF transmitter at the HAARP. Sideband emissions of unprecedented strength have been reported during recent campaigns at HAARP, reaching up to 10 dB relative to the reflected pump wave which are by far the strongest spectral features of secondary radiation that have been reported. These emissions known as narrowband SEE (NSEE) are shifted by only up to a few tens of Hertz from radio-waves transmitted at several megahertz. One of these new NSEE features are emission lines within 100 Hz of the pump frequency and are produced through magnetized stimulated Brillouin scatter (MSBS) process. Stimulated Brillouin Scatter (SBS) is a strong SEE mode involving a direct parametric decay of the pump wave into an electrostatic wave (ES) and a secondary EM wave that sometimes could be stronger than the HF pump. SBS has been studied in laboratory plasma experiments by the interaction of high power lasers with plasmas. The SBS instability in magnetized ionospheric plasma was observed for the first time at HAARP in 2010. Our recent work at HAARP has shown that MSBS emission lines can be used to asses electron temperature in the heated region, ion mass spectrometry, determine minor ion species and their densities in the ionosphere, study the physics associated with electron acceleration and artificial airglow. Here, we present new observations of narrowband SEE (NSEE) features at the new mid-latitude heating facility at Arecibo. This includes the direct mode conversion of pump wave through MSBS process. Collected data using ground-based SEE receiver, incoherent scatter radar (ISR), ionospgram, as well as satellite observations will be discussed. The different characteristics of parametric decay instabilities in the high and mid-latitude will be compared. Preliminary theoretical and computational modeling of mid-latitude NSEE will be presented.

HAARP-based Investigations of Lightning-induced Nonlinearities within the D-Region Ionosphere

NASA Astrophysics Data System (ADS)

Moore, R. C.

2015-12-01

It is well-documented that energetic lightning can produce fantastical events with the lower ionosphere. Although the High-frequency Active Auroral Research Program (HAARP) transmitter is not as powerful as lightning, it can be used to investigate the nonlinear interactions that occur within the lower ionosphere, many of which also occur during lightning-induced ionospheric events. This paper presents the best experimental results obtained during D-region modification experiments performed by the University of Florida at the HAARP observatory between 2007 and 2014, including ELF/VLF wave generation experiments, wave-wave mixing experiments, and cross-modulation experiments. We emphasize the physical processes important for lightning-ionosphere interactions that can be directly investigated using HAARP.

Detection and Analysis of Partial Reflections of HF Waves from the Lower Ionosphere

NASA Astrophysics Data System (ADS)

Erdman, A.; Moore, R. C.

2016-12-01

On the afternoon of August 27, 2011, the western half of the High Frequency Active Auroral Research Program's (HAARP's) HF transmitter repeatedly broadcast a low-power (1 kW/Tx), 4.5-MHz, X-mode polarized, 10 microsecond pulse. The HF beam was directed vertically, and the inter-pulse period was 20 milliseconds. HF observations were performed at Oasis (62° 23' 30" N, 145° 9' 03" W) using two crossed 90-foot folded dipoles. Observations clearly indicate the detection of a ground wave and multiple reflections from different sources at F-region altitudes, which is consistent with digisonde measurements at 4.5 MHz. Additional reflections were detected at a virtual altitude of 90-110 km, and we interpret these reflections as partial reflections from the rapid conductivity change at the base of the ionosphere. We compare these observations with the predictions of a new finite-difference time-domain (FDTD) plasma model. The model is a one-dimensional, second-order accurate, cold plasma FDTD model of the ionosphere extending from ground through the lower F-region. The model accounts for a spatially varying plasma frequency, cyclotron frequency, and electron-neutral collision frequency. We discuss the possibility to analyze partial reflections from the base of the ionosphere as a function of frequency to characterize the reflecting plasma.

VLF wave generation by beating of two HF waves in the ionosphere

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Kossey, Paul; Chang, Chia-Lie; Labenski, John

2011-05-01

Theory of a beat-wave mechanism for very low frequency (VLF) wave generation in the ionosphere is presented. The VLF current is produced by beating two high power HF waves of slightly different frequencies through the nonlinearity and inhomogeneity of the ionospheric plasma. Theory also shows that the density irregularities can enhance the beat-wave generation. An experiment was conducted by transmitting two high power HF waves of 3.2 MHz and 3.2 MHz + f, where f = 5, 8, 13, and 2.02 kHz, from the HAARP transmitter. In the experiment, the ionosphere was underdense to the O-mode heater, i.e., the heater frequency f0 > foF2, and overdense or slightly underdense to the X-mode heater, i.e., f0 < fxF2 or f0 ≥ fxF2. The radiation intensity increased with the VLF wave frequency, was much stronger with the X-mode heaters, and was not sensitive to the electrojet. The strongest VLF radiation of 13 kHz was generated when the reflection layer of the X-mode heater was just slightly below the foF2 layer and the spread of the O-mode sounding echoes had the largest enhancement, suggesting an optimal setting for beat-wave generation of VLF waves by the HF heaters.

100 Days of ELF/VLF Generation via HF Heating with HAARP (Invited)

NASA Astrophysics Data System (ADS)

Cohen, M.; Golkowski, M.

2013-12-01

ELF/VLF radio waves are difficult to generate with conventional antennas. Ionospheric HF heating facilities generate ELF/VLF waves via modulated heating of the lower ionosphere. HF heating of the ionosphere changes the lower ionospheric conductivity, which in the presence of natural currents such as the auroral electrojet, creates an antenna in the sky when heating is modulated at ELF/VLF frequencies. We present a summary of nearly 100 days of ELF/VLF wave generation experiments at the 3.6 MW HAARP facility near Gakona, Alaska, and provide a baseline reference of ELF/VLF generation capabilities with HF heating. Between February 2007 and August 2008, HAARP was operated on close to 100 days for ELF/VLF wave generation experiments, at a variety of ELF/VLF frequencies, seasons and times of day. We present comprehensive statistics of generated ELF/VLF magnetic fields observed at a nearby site, in the 500-3500 Hz band. Transmissions with a specific HF beam configuration (3.25 MHz, vertical beam, amplitude modulation) are isolated so the data comparison is self-consistent, across nearly 5 million individual measurements of either a tone or a piece of a frequency-time ramp. There is a minimum in the average generation close to local midnight. It is found that generation during local nighttime is on average weaker, but more highly variable, with a small number of very strong generation periods. Signal amplitudes from day to day may vary by as much as 20-30 dB. Generation strengthens by ~5 dB during the first ~30 minutes of transmission, which may be a signature of slow electron density changes from sustained HF heating. Theoretical calculations are made to relate the amplitude observed to the power injected into the waveguide and reaching 250 km. The median power generated by HAARP and injected into the waveguide is ~0.05-0.1 W in this base-line configuration (vertical beam, 3.25 MHz, amplitude modulation), but may have generated hundreds of Watts for brief durations. Several efficiency improvements have improved the ELF/VLF wave generation efficiency further.

Recent Observations and Modeling of Narrowband Stimulated Electromagnetic Emissions SEEs at HAARP and EISCAT

NASA Astrophysics Data System (ADS)

Scales, W.; Mahmoudian, A.; Fu, H.; Bordikar, M. R.; Samimi, A.; Bernhardt, P. A.; Briczinski, S. J., Jr.; Kosch, M. J.; Senior, A.; Isham, B.

2014-12-01

There has been significant interest in so-called narrowband Stimulated Electromagnetic Emission SEE over the past several years due to recent discoveries at the High Frequency Active Auroral Research Program HAARP facility near Gakone, Alaska. Narrowband SEE (NSEE) has been defined as spectral features in the SEE spectrum typically within 1 kHz of the transmitter (or pump) frequency. SEE is due to nonlinear processes leading to re-radiation at frequencies other than the pump wave frequency during heating the ionospheric plasma with high power HF radio waves. Although NSEE exhibits a richly complex structure, it has now been shown after a substantial number of observations at HAARP, that NSEE can be grouped into two basic classes. The first are those spectral features, associated with Stimulated Brillouin Scatter SBS, which typically occur when the pump frequency is not close to electron gyro-harmonic frequencies. Typically, these spectral features are within roughly 50 Hz of the pump wave frequency where it is to be noted that the O+ ion gyro-frequency is roughly 50 Hz. The second class of spectral features corresponds to the case when the pump wave frequency is typically within roughly 10 kHz of electron gyro-harmonic frequencies. In this case, spectral features ordered by harmonics of ion gyro-frequencies are typically observed, and termed Stimulated Ion Bernstein Scatter SIBS. This presentation will first provide an overview of the recent NSEE experimental observations at HAARP. Both Stimulated Brillouin Scatter SBS and Stimulated Ion Bernstein Scatter SIBS observations will be discussed as well as their relationship to each other. Possible theoretical formulation in terms of parametric decay instabilities and computational modeling will be provided. Possible applications of NSEE will be pointed out including triggering diagnostics for artificial ionization layer formation, proton precipitation event diagnostics, electron temperature measurements in the heated volume and detection of heavy ion species. Finally potential for observing such SEE at the European Incoherent Scatter EISCAT facility will be discussed.

Recent Science Campaigns at HAARP

NASA Astrophysics Data System (ADS)

McCoy, R. P.; Bristow, W. A.; Fallen, C. T.

2017-12-01

Experiments in HF ionospheric heating using the High­frequency Active Auroral Research Program (HAARP) facilities have tremendous potential for informing our investigation of the Earth's upper atmosphere, ionosphere, and magnetosphere. They provide a unique opportunity for quantifying and modeling the multi­scale coupled processes that characterize the interactions between the plasma in near­Earth space, the Earth's magnetic field, and the neutral gasses of the atmosphere. Physical parameters of the region are often difficult to measure with ground­based instruments, and the measurements that are possible are often poorly resolved in range or time or unavailable outside narrow altitude regimes. HF ionospheric modification experiments allow us to measure ionospheric and thermospheric state parameters more systematically and over a broader range of conditions than would otherwise be possible. HAARP is the world's most powerful and most flexible HF transmitting facility, capable of generating 3.6 MW of RF power over a frequency range from about 2 MHz to about 10 MHz. The electronic phased array antenna provides the ability to direct the RF energy to a large region of the sky above Alaska. HAARP was constructed through a research program managed by the Air Force Research Laboratory (AFRL), and the Office of Naval Research (ONR). It was jointly funded by AFRL, ONR, and the Defense Advanced Projects Research Agency (DARPA). These agencies ended of their program of HAARP research in 2014, and donated the site equipment to the University of Alaska, Fairbanks (UAF), in the summer of 2015, who now operate the facility as an international observatory for radio plasma heating and subauroral physics. Since taking control of HAARP, UAF has carried out research campaigns in February 2017, and September 2017. The topics investigated in the campaigns included the physics of ionospheric irregularities (FAI), the stimulated electromagnetic emissions (SEE), generation of optical emissions from the heated region, and technological impacts of irregularities. This paper will give an overview of the status of the facility and will present preliminary results from the experiments carried out in the campaigns.

Optimization of VLf/ELF Wave Generation using Beam Painting

NASA Astrophysics Data System (ADS)

Robinson, A.; Moore, R. C.

2017-12-01

A novel optimized beam painting algorithm (OBP) is used to generate high amplitude very low frequency (VLF) and extremely low frequency (ELF) waves in the D-region of the ionosphere above the High-frequency Active Auroral Research Program (HAARP) observatory. The OBP method creates a phased array of sources in the ionosphere by varying the azimuth and zenith angles of the high frequency (HF) transmitter to capitalize on the constructive interference of propagating VLF/ELF waves. OBP generates higher amplitude VLF/ELF signals than any other previously proposed method. From April through June during 2014, OBP was performed at HAARP over 1200 times. We compare the BP generated signals against vertical amplitude modulated transmissions at 50 % duty cycle (V), oblique amplitude modulated transmissions at 15 degrees zenith and 81 degrees azimuth at 50 % duty cycle (O), and geometric (circle-sweep) modulation at 15 degrees off-zenith angle at 1562.5 Hz, 3125 Hz, and 5000 Hz. We present an analysis of the directional dependence of each signal, its polarization, and its dependence on the properties of the different source region elements. We find that BP increases the received signal amplitudes of VLF and ELF waves when compared to V, O, and GM methods over a statistically significant number of trials.

Recent Advances in Narrowband Stimulated Electromagnetic Emission NSEE Investigations at HAARP and EISCAT

NASA Astrophysics Data System (ADS)

Scales, Wayne

2016-07-01

Investigation of stimulated radiation, commonly known as Stimulated Electromagnetic Emissions (SEE), produced by the interaction of high-power, High Frequency HF radiowaves with the ionospheric plasma has been a vibrant area of research since the early 1980's. Substantial diagnostic information about ionospheric plasma characteristics, dynamics, and turbulence can be obtained from the frequency spectrum of the stimulated radiation. During the past several decades, so-called wideband SEE (WSEE) which exists in a frequency band of ±100 KHz or so of the transmit wave frequency (which is several MHz) has been investigated relatively thoroughly. Upgrades both in transmitter power and diagnostic receiver frequency sensitivity at major ionosphere interaction facilities (i.e. HAARP and EISCAT) have allowed new breakthroughs in the ability to study a plethora of processes associated with the ionospheric plasma during these active experiments. A primary advance is in observations of so-called narrowband SEE (NSEE) which exists roughly within ±1 kHz of the transmit wave frequency. NSEE investigation has opened the door for a potentially powerful tool for aeronomy investigations as well. An overview of several important new results associated with NSEE are discussed in this presentation, including observations, theory, computational modeling, as well as implications to new diagnostics of space plasma physics occurring during ionospheric interaction experiments.

SATSIN System Manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livingston, R.C.

1995-01-01

This report outlines the design, functions and operation of the HAARP Diagnostic Satellite Scintillation (SATSIN) system that will be used to characterize the structure and dynamics of F region ionospheric irregularities created during HF heating. When in routine operation, the SATSIN system will be located so that the propagation path from satellite radio beacons passes through the heated volume created by HAARP. The signal, altered in phase and amplitude by the irregularities, is received by the SATSIN array of eight antennas and is processed to extract the spatial and temporal characteristics of the scintillation. From this information, the strength, shapemore » and motion of the in situ irregularities generated by HAARP can be implied. The hardware and software components of the system are reviewed, and the installation and operation in conjunction with the HAARP network are outlined.« less

UHF Radar observations at HAARP with HF pump frequencies near electron gyro-harmonics and associated ionospheric effects

NASA Astrophysics Data System (ADS)

Watkins, Brenton; Fallen, Christopher; Secan, James

Results for HF modification experiments at the HAARP facility in Alaska are presented for experiments with the HF pump frequency near third and fourth electron gyro-harmonics. A UHF diagnostic radar with range resolution of 600 m was used to determine time-dependent altitudes of scattering from plasma turbulence during heating experiments. Experiments were conducted with multiple HF frequencies stepped by 20 kHz above and below the gyro-harmonic values. During times of HF heating the HAARP facility has sufficient power to enhance large-scale ionospheric densities in the lower ionosphere (about 150-200 km altitude) and also in the topside ionosphere (above about 350 km). In the lower ionosphere, time-dependent decreases of the altitude of radar scatter result from electron density enhancements. The effects are substantially different even for relatively small frequency steps of 20 kHz. In all cases the time-varying altitude decrease of radar scatter stops about 5-10 km below the gyro-harmonic altitude that is frequency dependent; we infer that electron density enhancements stop at this altitude where the radar signals stop decreasing with altitude. Experiments with corresponding total electron content (TEC) data show that for HF interaction altitudes above about 170 km there is substantial topside electron density increases due to upward electron thermal conduction. For lower altitudes of HF interaction the majority of the thermal energy is transferred to the neutral gas and no significant topside density increases are observed. By selecting an appropriate HF frequency a little greater than the gyro-harmonic value we have demonstrated that the ionospheric response to HF heating is a self-oscillating mode where the HF interaction altitude moves up and down with a period of several minutes. If the interaction region is above about 170 km this also produces a continuously enhanced topside electron density and upward plasma flux. Experiments using an FM scan with the HF frequency increasing near the gyro-harmonic value were conducted. The FM scan rate was sufficiently slow that the electron density was approximately in an equilibrium state. For these experiments the altitude of the HF interaction follows a near straight line downward parallel to the altitude-dependent gyro-harmonic level.

Studies of the ionospheric turbulence excited by the fourth gyroharmonic at HAARP

NASA Astrophysics Data System (ADS)

Najmi, A.; Milikh, G.; Yampolski, Y. M.; Koloskov, A. V.; Sopin, A. A.; Zalizovski, A.; Bernhardt, P.; Briczinski, S.; Siefring, C.; Chiang, K.; Morton, Y.; Taylor, S.; Mahmoudian, A.; Bristow, W.; Ruohoniemi, M.; Papadopoulos, K.

2015-08-01

A study is presented of artificial ionospheric turbulence (AIT) induced by HF heating at High Frequency Active Auroral Research Program (HAARP) using frequencies close to the fourth electron gyroharmonic, in a broad range of radiated powers and using a number of different diagnostics. The diagnostics include GPS scintillations, ground-based stimulated electromagnetic emission (SEE), the HAARP ionosonde, Kodiak radar, and signals received at the Ukrainian Antarctic Station (UAS). The latter allowed analysis of waves scattered by the AIT into the ionospheric waveguide along Earth's terminator, 15.6 mm from the HAARP facility. For the first time, the amplitudes of two prominent SEE features, the downshifted maximum and broad upshifted maximum, were observed to saturate at ~50% of the maximum HAARP effective radiated power. Nonlinear effects in slant total electron content, SEE, and signals received at UAS at different transmitted frequencies and intensities of the pump wave were observed. The correlations between the data from different detectors demonstrate that the scattered waves reach UAS by the waveguide along the Earth's terminator, and that they were injected into the waveguide by scattering off of artificial striations produced by AIT above HAARP, rather than via direct injection from sidelobe radiation.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, William; Hysell, David

2016-07-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Observations of HF backscatter decay rates from HAARP generated FAI

NASA Astrophysics Data System (ADS)

Bristow, W. A.; Hysell, D. L.

2016-12-01

Suitable experiments at the High-frequency Active Auroral Research Program (HAARP) facilities in Gakona, Alaska, create a region of ionospheric Field-Aligned Irregularities (FAI) that produces strong radar backscatter observed by the SuperDARN radar on Kodiak Island, Alaska. Creation of FAI in HF ionospheric modification experiments has been studied by a number of authors who have developed a rich theoretical background. The decay of the irregularities, however, has not been so widely studied yet it has the potential for providing estimates of the parameters of natural irregularity diffusion, which are difficult measure by other means. Hysell, et al. [1996] demonstrated using the decay of radar scatter above the Sura heating facility to estimate irregularity diffusion. A large database of radar backscatter from HAARP generated FAI has been collected over the years. Experiments often cycled the heater power on and off in a way that allowed estimates of the FAI decay rate. The database has been examined to extract decay time estimates and diffusion rates over a range of ionospheric conditions. This presentation will summarize the database and the estimated diffusion rates, and will discuss the potential for targeted experiments for aeronomy measurements. Hysell, D. L., M. C. Kelley, Y. M. Yampolski, V. S. Beley, A. V. Koloskov, P. V. Ponomarenko, and O. F. Tyrnov, HF radar observations of decaying artificial field aligned irregularities, J. Geophys. Res. , 101, 26,981, 1996.

Applications of a time-dependent polar ionosphere model for radio modification experiments

NASA Astrophysics Data System (ADS)

Fallen, Christopher Thomas

A time-dependent self-consistent ionosphere model (SLIM) has been developed to study the response of the polar ionosphere to radio modification experiments, similar to those conducted at the High-Frequency Active Auroral Research Program (HAARP) facility in Gakona, Alaska. SCIM solves the ion continuity and momentum equations, coupled with average electron and ion gas energy equations; it is validated by reproducing the diurnal variation of the daytime ionosphere critical frequency, as measured with an ionosonde. Powerful high-frequency (HF) electromagnetic waves can drive naturally occurring electrostatic plasma waves, enhancing the ionospheric reflectivity to ultra-high frequency (UHF) radar near the HF-interaction region as well as heating the electron gas. Measurements made during active experiments are compared with model calculations to clarify fundamental altitude-dependent physical processes governing the vertical composition and temperature of the polar ionosphere. The modular UHF ionosphere radar (MUIR), co-located with HAARP, measured HF-enhanced ion-line (HFIL) reflection height and observed that it ascended above its original altitude after the ionosphere had been HF-heated for several minutes. The HFIL ascent is found to follow from HF-induced depletion of plasma surrounding the F-region peak density layer, due to temperature-enhanced transport of atomic oxygen ions along the geomagnetic field line. The lower F-region and topside ionosphere also respond to HF heating. Model results show that electron temperature increases will lead to suppression of molecular ion recombination rates in the lower F region and enhancements of ambipolar diffusion in the topside ionosphere, resulting in a net enhancement of slant total electron content (TEC); these results have been confirmed by experiment. Additional evidence for the model-predicted topside ionosphere density enhancements via ambipolar diffusion is provided by in-situ measurements of ion density and vertical velocity over HAARP made by a Defense Meteorological Satellite Program (DMSP) satellite.

Large-Scale Ionospheric Effects Related to Electron-Gyro Harmonics: What We Have Learned from HAARP.

NASA Astrophysics Data System (ADS)

Watkins, B. J.; Fallen, C. T.; Secan, J. A.

2014-12-01

The HAARP ionospheric modification facility has unique capabilities that enable a wide range of HF frequencies with transmit powers ranging from very low to very high values. We will review a range of experiment results that illustrate large-scale ionospheric effects when the HF frequencies used are close to electron gyro-harmoncs and we focus mainly on the 3rd and 4th harmonics. The data are primarily from the UHF diagnosticc radar and total electron content (TEC) observations through the heated topside ionosphere. Radar data for HF frequencies just above and just below gyro harmoncs show significant differences in radar scatter cross-section that suggest differing plasma processes, and this effect is HF power dependent with some effects only observable with full HF power. For the production of artificial ionization in the E-region when the HF frequency is near gyro-harmoncs the results differ significantly for relatively small (50 kHz) variations in the HF frequency. We show how slow FM scans in conjunction with gyro-harmonic effects are effective in producing artificial ionization in the lower ionosphere.In the topside ionosphere enhanced density and upward fluxes have been observed and these may act as effective ducts for the propagation of VLF waves upward into the magneosphere. Experimental techniques have been developed that may be used to continuously maintain these effects in the topside ionossphere.

Prompt Ion Outflows and Artificial Ducts during High-Power HF Heating at HAARP: Effect of Suprathermal Electrons?

NASA Astrophysics Data System (ADS)

Mishin, E. V.; Milikh, G. M.

2014-12-01

In situ observations from the DMSP and Demeter satellites established that high-power HF heating of the ionosphere F-region results in significant ion outflows associated with 10-30% density enhancements in the topside ionosphere magnetically-conjugate to the heated region. As follows from the SAMI2 two-fluid model calculations, their formation time should exceed 5-7 minutes. However, specially designed DMSP-HAARP experiments have shown that artificial ducts and ion outflows appear on the topside within 2 minutes. We describe the results of these observations and present a semi-quantitative explanation of the fast timescale due to suprathermal electrons accelerated by HF-induced plasma turbulence. There are two possible effects of suprathermal electrons: (1) the increase of the ambipolar electric field over the usual thermal ambipolar diffusion and (2) excitation of heat flux-driven plasma instability resulting in an anomalous electron-ion momentum exchange. Both effects result in faster upward ion flows.

Detection of Transionospheric SuperDARN HF Waves by the Radio Receiver Instrument on the enhanced Polar Outflow Probe Satellite

NASA Astrophysics Data System (ADS)

Gillies, R. G.; Yau, A. W.; James, H. G.; Hussey, G. C.; McWilliams, K. A.

2014-12-01

The enhanced Polar Outflow Probe (ePOP) Canadian small-satellite was launched in September 2013. Included in this suite of eight scientific instruments is the Radio Receiver Instrument (RRI). The RRI has been used to measure VLF and HF radio waves from various ground and spontaneous ionospheric sources. The first dedicated ground transmission that was detected by RRI was from the Saskatoon Super Dual Auroral Radar Network (SuperDARN) radar on Nov. 7, 2013 at 14 MHz. Several other passes over the Saskatoon SuperDARN radar have been recorded since then. Ground transmissions have also been observed from other radars, such as the SPEAR, HAARP, and SURA ionospheric heaters. However, the focus of this study will be on the results obtained from the SuperDARN passes. An analysis of the signal recorded by the RRI provides estimates of signal power, Doppler shift, polarization, absolute time delay, differential mode delay, and angle of arrival. By comparing these parameters to similar parameters derived from ray tracing simulations, ionospheric electron density structures may be detected and measured. Further analysis of the results from the other ground transmitters and future SuperDARN passes will be used to refine these results.

ELF/VLF Perturbations Above the Haarp Transmitter Recorded by the Demeter Satellite in the Upper Ionosphere

NASA Astrophysics Data System (ADS)

Titova, E. E.; Demekhov, A. G.; Mochalov, A. A.; Gvozdevsky, B. B.; Mogilevsky, M. M.; Parrot, M.

2015-08-01

In the studies of the data received from DEMETER (orbit altitude above the Earth is about 700 km), we detected for the first time electromagnetic perturbations, which are due to the ionospheric modification by HAARP, a high-power high-frequency transmitter, simultaneously in the extremely low-frequency (ELF, below 1200 Hz) and very low-frequency (VLF, below 20 kHz) ranges. Of the thirteen analyzed flybys of the satellite above the heated area, the ELF/VLF signals were detected in three cases in the daytime (LT = 11-12 h), when the minimum distance between the geomagnetic projections of the satellite and the heated area center on the Earth's surface did not exceed 31 km. During the nighttime flybys, the ELF/VLF perturbations were not detected. The size of the perturbed region was about 100 km. The amplitude, spectrum, and polarization of the ELF perturbations were analyzed, and their comparison with the characteristics of natural ELF noise above the HAARP transmitter was performed. In particular, it was shown that in the daytime the ELF perturbation amplitude above the heated area can exceed by a factor of 3 to 8 the amplitude of natural ELF noise. The absence of the nighttime records of artificial ELF/VLF perturbations above the heated area can be due to both the lower frequency of the heating signal, at which the heating occurs in the lower ionosphere, and the higher level of natural noise. The spectrum of the VLF signals related to the HAARP transmitter operation had two peaks at frequencies of 8 to 10 kHz and 15 to 18 kHz, which are close to the first and second harmonics of the lower-hybrid resonance in the heated area. The effect of the whistler wave propagation near the lower-hybrid resonance region on the perturbation spectrum recorded in the upper ionosphere for these signals has been demonstrated. In particular, some of the spectrum features can be explained by assuming that the VLF signals propagate in quasiresonance, rather than quasilongitudinal, regime. It is noted that the profile and dynamics of the ELF perturbation frequency spectrum conform to the assumption of their connection with quasistatic small-scale electron-density inhomogeneities occurring in the heated region and having lifetimes of a few seconds or more. The possible mechanisms of the ELF/VLF perturbation formation in the ionospheric plasma above the high-latitude HAARP facility at the DEMETER flyby altitudes are discussed.

Stimulated Brillouin scattering during electron gyro-harmonic heating at EISCAT

NASA Astrophysics Data System (ADS)

Fu, H. Y.; Scales, W. A.; Bernhardt, P. A.; Briczinski, S. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.; Ruohoniemi, J. M.

2015-08-01

Observations of secondary radiation, stimulated electromagnetic emission (SEE), produced during ionospheric modification experiments using ground-based, high-power, high-frequency (HF) radio waves are considered. The High Frequency Active Auroral Research Program (HAARP) facility is capable of generating narrowband SEE in the form of stimulated Brillouin scatter (SBS) and stimulated ion Bernstein scatter (SIBS) in the SEE spectrum. Such narrowband SEE spectral lines have not been reported using the European Incoherent Scatter (EISCAT) heater facility before. This work reports the first EISCAT results of narrowband SEE spectra and compares them to SEE previously observed at HAARP during electron gyro-harmonic heating. An analysis of experimental SEE data shows observations of emission lines within 100 Hz of the pump frequency, interpreted as SBS, during the 2012 July EISCAT campaign. Experimental results indicate that SBS strengthens as the pump frequency approaches the third electron gyro-harmonic. Also, for different heater antenna beam angles, the CUTLASS radar backscatter induced by HF radio pumping is suppressed near electron gyro-harmonics, whereas electron temperature enhancement weakens as measured by EISCAT/UHF radar. The main features of these new narrowband EISCAT observations are generally consistent with previous SBS measurements at HAARP.

Excitation of Ionospheric Alfvén Resonator with HAARP

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Chang, C.; Labenski, J.; Milikh, G. M.; Vartanyan, A.; Snyder, A. L.

2011-12-01

We report results from numerical and experimental studies of the excitation of ULF waves inside the ionospheric Alfvén resonator (IAR) by heating the ionosphere with powerful HF waves launched from the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Numerical simulations of the two-fluid MHD model describing IAR in a dipole magnetic field geometry with plasma parameters taken from the observations at HAARP during October-November 2010 experimental campaign reveal that the IAR quality is higher during night-time conditions, when the ionospheric conductivity is very low. Simulations also reveal that the resonance wave cannot be identified from the magnetic measurements on the ground or at an altitude above 600 km because the magnetic field in this wave has nodes on both ends of the resonator, and the best way to detect IAR modes is by measuring the electric field on low-Earth-orbit satellites. These theoretical predictions are in good, quantitative agreement with results from observations: In particular, 1) observations from the ground-based magnetometer at the HAARP site demonstrate no any significant difference in the amplitudes of the magnetic field generated by HAARP in the frequency range from 0 to 5 Hz, and 2) the DEMETER satellite detected the electric field of the IAR first harmonic at an altitude of 670 km above HAARP during the heating experiment.

Ground and Satellite Observations of ULF Waves Artificially Produced by HAARP

NASA Astrophysics Data System (ADS)

Chang, C.; Labenski, J.; Shroff, H.; Doxas, I.; Papadopoulos, D.; Milikh, G.; Parrot, M.

2008-12-01

Modulated ionospheric heating at ULF frequencies using the HAARP heater was performed from April 28 to May 3, 2008 (http://www.haarp.alaska.edu). Simultaneous ground-based ULF measurements were made locally at Gakona, AK and at Lake Ozette, WA that is 2000 km away. The ground-based results showed that ULF amplitudes measured at Gakona are mostly proportional to the electrojet strength above HAARP, indicating electrojet modulation to be the source of the local ULF waves. However, the timing of ULF events recorded at Lake Ozette did not correlated with the electrojet strength at Gakona, indicating that modulation of F region pressure is the more likely source for distant ULF waves. These observations are consistent with the theoretical understanding that ULF waves generated by current modulation are shear Alfven waves propagating along the magnetic field line, thus at high latitude their observations are limited to the vicinity of the heated spot. On the other hand, propagation of ULF waves at significant lateral distances requires generation of magnetosonic waves since they are the only mode that propagates isotropically and can thus couple efficiently in the Alfvenic duct. In addition to ground-based observations, the DEMETER satellite also provided space measurements of the heating effects during its passes over HAARP. The DEMETER results showed direct detection of HAARP ULF waves at 0.1 Hz. Moreover, density dips were observed every time HAARP was operated at CW mode, which provides clear evidence of duct formation by direct HF heating at F peak. Details of these results will be presented at the meeting. We would like to acknowledge the support provided by the HAARP facility during our ULF experiments.

Recent Observations and Modeling of Narrowband Stimulated Electromagnetic Emissions SEEs at the HAARP Facility

NASA Astrophysics Data System (ADS)

Scales, Wayne; Bernhardt, Paul; McCarrick, Michael; Briczinski, Stanley; Mahmoudian, Alireza; Fu, Haiyang; Ranade Bordikar, Maitrayee; Samimi, Alireza

There has been significant interest in so-called narrowband Stimulated Electromagnetic Emission SEE over the past several years due to recent discoveries at the High Frequency Active Auroral Research Program HAARP facility near Gakone, Alaska. Narrowband SEE (NSEE) has been defined as spectral features in the SEE spectrum typically within 1 kHz of the transmitter (or pump) frequency. SEE is due to nonlinear processes leading to re-radiation at frequencies other than the pump wave frequency during heating the ionospheric plasma with high power HF radio waves. Although NSEE exhibits a richly complex structure, it has now been shown after a substantial number of observations at HAARP, that NSEE can be grouped into two basic classes. The first are those spectral features, associated with Stimulated Brillouin Scatter SBS, which typically occur when the pump frequency is not close to electron gyro-harmonic frequencies. Typically, these spectral features are within roughly 50 Hz of the pump wave frequency where it is to be noted that the O+ ion gyro-frequency is roughly 50 Hz. The second class of spectral features corresponds to the case when the pump wave frequency is typically within roughly 10 kHz of electron gyro-harmonic frequencies. In this case, spectral features ordered by harmonics of ion gyro-frequencies are typically observed, and termed Stimulated Ion Bernstein Scatter SIBS. There is also important parametric behavior on both classes of NSEE depending on the pump wave parameters including the field strength, antenna beam angle, and electron gyro-harmonic number. This presentation will first provide an overview of the recent NSEE experimental observations at HAARP. Both Stimulated Brillouin Scatter SBS and Stimulated Ion Bernstein Scatter SIBS observations will be discussed as well as their relationship to each other. Possible theoretical formulation in terms of parametric decay instabilities will be provided. Computer simulation model results will be presented to provide insight into associated higher order nonlinear effects including particle acceleration and wave-wave processes. Both theory and model results will be put into the context of the experimental observations. Finally, possible applications of NSEE will be pointed out including triggering diagnostics for artificial ionization layer formation, proton precipitation event diagnostics, and electron temperature measurements in the heated volume.

HF-enhanced 4278-Å airglow: evidence of accelerated ionosphere electrons?

NASA Astrophysics Data System (ADS)

Fallen, C. T.; Watkins, B. J.

2013-12-01

We report calculations from a one-dimensional physics-based self-consistent ionosphere model (SCIM) demonstrating that HF-heating of F-region electrons can produce 4278-Å airglow enhancements comparable in magnitude to those reported during ionosphere HF modification experiments at the High-frequency Active Auroral Research Program (HAARP) observatory in Alaska. These artificial 'blue-line' emissions, also observed at the EISCAT ionosphere heating facility in Norway, have been attributed to arise solely from additional production of N2+ ions through impact ionization of N2 molecules by HF-accelerated electrons. Each N2+ ion produced by impact ionization or photoionization has a probability of being created in the N2+(1N) excited state, resulting in a blue-line emission from the allowed transition to its ground state. The ionization potential of N2 exceeds 18 eV, so enhanced impact ionization of N2 implies that significant electron acceleration processes occur in the HF-modified ionosphere. Further, because of the fast N2+ emission time, measurements of 4278-Å intensity during ionosphere HF modification experiments at HAARP have also been used to estimate artificial ionization rates. To the best of our knowledge, all observations of HF-enhanced blue-line emissions have been made during twilight conditions when resonant scattering of sunlight by N2+ ions is a significant source of 4278-Å airglow. Our model calculations show that F-region electron heating by powerful O-mode HF waves transmitted from HAARP is sufficient to increase N2+ ion densities above the shadow height through temperature-enhanced ambipolar diffusion and temperature-suppressed ion recombination. Resonant scattering from the modified sunlit region can cause a 10-20 R increase in 4278-Å airglow intensity, comparable in magnitude to artificial emissions measured during ionosphere HF-modification experiments. This thermally-induced artificial 4278-Å aurora occurs independently of any artificial aurora maintained by HF-accelerated (non-thermal) electrons. The numerical results presented here do not necessarily rule out the presence of HF-accelerated electrons with energies exceeding 18 eV. However, vertical or field-aligned airglow intensity measurements made during twilight conditions do not provide definitive evidence of energetic HF-accelerated electrons. Consequently, artificial blue-line airglow measurements should not be used to estimate N2+ ionization rates without also accounting for temperature-dependent chemistry and diffusion. Future experiments that make simultaneous measurements of N2+ ion airglow emissions from both the first negative bands and the Meinel bands can potentially resolve the relative contributions of accelerated electron and resonant scattering mechanisms. Airglow emission rates from these bands are expected to be in strict proportion when the emissions result from electron impact ionization of N2 molecules. Side-view altitude-resolved 4278-Å airglow measurements may also indicate the presence of energetic HF-accelerated electrons if the blue-line emissions are determined to occur below the shadow height.

Detection of Heater Generated Super Small Scale Striations Using GPS Signal Diagnostics

NASA Astrophysics Data System (ADS)

Najmi, A. C.; Milikh, G. M.; Chiang, K.; Psiaki, M.; Secan, J. A.; Bernhardt, P. A.; Briczinski, S. J.; Siefring, C. L.; Papadopoulos, K.

2013-12-01

Recent theoretical models predict that super small striations (SSS) of the electron density, on the order of ten centimeters, can be excited by HF waves with frequency close to multiples of the electron gyro frequency [Gurevich et al., 2006]. The first experimental verification of SSS was made at HAARP [Milikh et al., 2008]. We present results of HAARP experiments that include simultaneous observations of GPS carrier phase and SEE observations of ionospheric turbulence. These observations show that SSS excited by HF frequencies near the fourth harmonic of the gyro frequency scatter GPS signals, and in three out of six experiments indicate the presence of strong turbulence, similar to that observed in descending artificial ionized layer experiments [Pedersen et al., 2010]. This turbulence is capable of generating suprathermal electrons, and in one of the experiments, the presence of fast electrons was confirmed by the HAARP incoherent scattering radar. Estimates on the SSS shows that they correspond to 3-10% electron density depletions. Such irregularities affect UHF signals including GPS, and thus can be important in applications. Gurevich, A.V. and K.P. Zybin (2006), Phys. Lett. A, 358, 159. Milikh, G., et al. (2008), Geophys. Res. Let., 35, L22102, doi:10.1029/2008GL035527. Pedersen, T. et al. (2010), Geophys. Res. Let., 37, L02106, doi:10.1029/2009GL041895.

Characteristics of VLF wave propagation in the Earth's magnetosphere in the presence of an artificial density duct

NASA Astrophysics Data System (ADS)

Pasmanik, Dmitry; Demekhov, Andrei

We study the propagation of VLF waves in the Earth's ionosphere and magnetosphere in the presence of large-scale artificial plasma inhomogeneities which can be created by HF heating facilities like HAARP and ``Sura''. A region with enhanced cold plasma density can be formed due to the action of HF heating. This region is extended along geomagnetic field (up to altitudes of several thousand km) and has rather small size across magnetic field (about 1 degree). The geometric-optical approximation is used to study wave propagation. The plasma density and ion composition are calculated with the use of SAMI2 model, which was modified to take the effect of HF heating into account. We calculate ray trajectories of waves with different initial frequency and wave-normal angles and originating at altitudes of about 100 km in the region near the heating area. The source of such waves could be the lightning discharges, modulated HF heating of the ionosphere, or VLF transmitters. Variation of the wave amplitude along the ray trajectories due to refraction is considered and spatial distribution of wave intensity in the magnetosphere is analyzed. We show that the presence of such a density disturbances can lead to significant changes of wave propagation trajectories, in particular, to efficient guiding of VLF waves in this region. This can result in a drastic increase of the VLF-wave intensity in the density duct. The dependence of wave propagation properties on parameters of heating facility operation regime is considered. We study the variation of the spatial distribution of VLF wave intensity related to the slow evolution of the artificial inhomogeneity during the heating.

Excitation of the ionospheric Alfvén resonator from the ground: Theory and experiments

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Chang, C.-L.; Labenski, J.; Milikh, G.; Vartanyan, A.; Snyder, A. L.

2011-10-01

We report results from numerical and experimental studies of the excitation of ULF shear Alfvén waves inside the ionospheric Alfvén resonator (IAR) by heating the ionosphere with powerful HF waves launched from the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Numerical simulations of the two-fluid MHD model describing IAR in a dipole magnetic field geometry with plasma parameters taken from the observations at HAARP during the October-November 2010 experimental campaign reveal that the IAR quality is higher during nighttime conditions, when the ionospheric conductivity is very low. Simulations also reveal that the resonance wave cannot be identified from the magnetic measurements on the ground or at an altitude above 600 km because the magnetic field in this wave has nodes on both ends of the resonator, and the best way to detect IAR modes is by measuring the electric field on low Earth orbit satellites. These theoretical predictions are in good, quantitative agreement with results from observations: In particular, (1) observations from the ground-based magnetometer at the HAARP site demonstrate no significant difference in the amplitudes of the magnetic field generated by HAARP in the frequency range from 0 to 5 Hz, and (2) the DEMETER satellite detected the electric field of the IAR first harmonic at an altitude of 670 km above HAARP during the heating experiment.

SEE Observations of Ionospheric Heating from HAARP Using Orbital Angular Momentum

NASA Astrophysics Data System (ADS)

Briczinski, S. J.; Bernhardt, P. A.; Siefring, C. L.

2013-12-01

High power HF radio waves exciting the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaksa is the world's largest heating facility, providing effective radiated powers in the gigawatt range. Experiments performed at HAARP have allowed researchers to study many non-linear effects of wave-plasma interactions. Stimulated Electromagnetic Emission (SEE) is of interest to the ionospheric community for its diagnostic purposes. Typical SEE experiments at HAARP have focused on characterizing the parametric decay of the electromagnetic pump wave into several different wave modes such as upper and lower hybrid, ion acoustic, ion-Bernstein and electron-Bernstein. These production modes have been extensively studied at HAARP using traditional beam heating patterns and SEE detection. New results are present from HAARP experiments using an excitation mode that attempts to impart orbital angular momentum (OAM) into the heating region. This OAM mode is also referred to as a 'twisted beam.' Previous analysis of twisted beam heating shows that the SEE results obtained are nearly identical to the modes without OAM. Recent twisted beam heating experiments have produced SEE modes not previously characterized. These new modes are presented and discussed. One difference in the twisted beam mode is the heating region produced is in the shape of a ring as opposed to the more traditional 'solid spot' region. The ring heating pattern may be more conducive to the creation of artificial ionization clouds. The results of these runs include artificial ionization creation and evolution as pertaining to the twisted beam pattern.

On the altitude-variation of electron acceleration by HF radio-waves in the F-region

NASA Astrophysics Data System (ADS)

Gustavsson, Bjorn

2016-07-01

I will talk about artificial aurora, the descending layers we have observed at HAARP and the altitude-variations we have observed in enhanced ion and plasma-lines with the EISCAT UHF-radar, and present an empirical model describing these phenomena.

"Twisted Beam" SEE Observations of Ionospheric Heating from HAARP

NASA Astrophysics Data System (ADS)

Briczinski, S. J.; Bernhardt, P. A.; Siefring, C. L.; Han, S.-M.; Pedersen, T. R.; Scales, W. A.

2015-10-01

Nonlinear interactions of high power HF radio waves in the ionosphere provide aeronomers with a unique space-based laboratory capability. The High-Frequency Active Auroral Research Program (HAARP) in Gakona, Alaska is the world's largest heating facility, yielding effective radiated powers in the gigawatt range. New results are present from HAARP experiments using a "twisted beam" excitation mode. Analysis of twisted beam heating shows that the SEE results obtained are identical to more traditional patterns. One difference in the twisted beam mode is the heating region produced is in the shape of a ring as opposed to the more traditional "solid spot" region from a pencil beam. The ring heating pattern may be more conducive to the creation of stable artificial airglow layers because of the horizontal structure of the ring. The results of these runs include artificial layer creation and evolution as pertaining to the twisted beam pattern. The SEE measurements aid the interpretation of the twisted beam interactions in the ionosphere.

Nonlinear Interactions within the D-Region Ionosphere

NASA Astrophysics Data System (ADS)

Moore, Robert

2016-07-01

This paper highlights the best results obtained during D-region modification experiments performed by the University of Florida at the High-frequency Active Auroral Research Program (HAARP) observatory between 2007 and 2014. Over this period, we saw a tremendous improvement in ELF/VLF wave generation efficiency. We identified methods to characterize ambient and modified ionospheric properties and to discern and quantify specific types of interactions. We have demonstrated several important implications of HF cross-modulation effects, including "Doppler Spoofing" on HF radio waves. Throughout this talk, observations are compared with the predictions of an ionospheric HF heating model to provide context and guidance for future D-region modification experiments.

Artificial Ionization and UHF Radar Response Associated with HF Frequencies near Electron Gyro-Harmonics (Invited)

NASA Astrophysics Data System (ADS)

Watkins, B. J.; Fallen, C. T.; Secan, J. A.

2013-12-01

We present new results from O-mode ionospheric heating experiments at the HAARP facility in Alaska to demonstrate that the magnitude of artificial ionization production is critically dependent on the choice of HF frequency near gyro-harmonics. For O-mode heating in the lower F-region ionosphere, typically about 200 km altitude, artificial ionization enhancements are observed in the lower ionosphere (about 150 - 220 km) and also in the topside ionosphere above about 500 km. Lower ionosphere density enhancements are inferred from HF-enhanced ion and plasma-line signals observed with UHF radar. Upper ionospheric density enhancements have been observed with TEC (total electron content) experiments by monitoring satellite radio beacons where signal paths traverse the HF-modified ionosphere. Both density enhancements and corresponding upward plasma fluxes have also been observed in the upper ionosphere via in-situ satellite observations. The data presented focus mainly on observations near the third and fourth gyro-harmonics. The specific values of the height-dependent gyro-harmonics have been computed from a magnetic model of the field line through the HF heated volume. Experiments with several closely spaced HF frequencies around the gyro-harmonic frequency region show that the magnitude of the lower-ionosphere artificial ionization production maximizes for HF frequencies about 1.0 - 1.5 MHz above the gyro-harmonic frequency. The response is progressively larger as the HF frequency is increased in the frequency region near the gyro-harmonics. For HF frequencies that are initially greater than the gyro-harmonic value the UHF radar scattering cross-section is relatively small, and non-existent or very weak signals are observed; as the signal returns drop in altitude due to density enhancements the HF interaction region passes through lower altitudes where the HF frequency is less than the gyro-harmonic value, for these conditions the radar scattering cross-section is significantly increased and strong signals persist while the high-power HF is present . Simultaneous observations of topside TEC measurements and lower-ionosphere UHF radar observations suggest there is an optimum altitude region to heat the lower F-region in order to produce topside ionosphere density enhancements. The observations are dependent on HF power levels and we show several examples where heating results are only observed for the high-power levels attainable with the HAARP facility.

High Power Radio Wave Interactions within the D-Region Ionosphere

NASA Astrophysics Data System (ADS)

Moore, R. C.

2014-12-01

This paper highlights the best results obtained during D-region modification experiments performed by the University of Florida at the High-frequency Active Auroral Research Program (HAARP) observatory between 2007 and 2014. Over this period, we have seen a tremendous improvement in ELF/VLF wave generation efficiency. We have identified methods to characterize ambient and modified ionospheric properties and to discern and quantify specific types of interactions. We have demonstrated several important implications of HF cross-modulation effects, including "Doppler Spoofing" on HF radio waves. Throughout this talk, observations are compared with the predictions of an ionospheric HF heating model to provide context and guidance for future D-region modification experiments.

Investigation of third gyro-harmonic heating at HAARP using stimulated radio emissions and the MUIR and Kodiak radars

NASA Astrophysics Data System (ADS)

Mahmoudian, A.; Scales, W. A.; Watkins, B. J.; Bernhardt, P. A.; Isham, B.; Vega-Cancel, O.; Ruohoniemi, J. M.

2017-01-01

This paper presents data from two campaigns at the High Frequency Active Auroral Research Program facility (HAARP) in 2011 and 2012. The measurements of stimulated radio emissions (often called stimulated electromagnetic emissions or SEE) were conducted 15 km from the HAARP site. The potential of Narrowband SEE (NSEE) as a new diagnostic tool to monitor artificial irregularities excited during HF-pump heating of the ionosphere is the main goal of this paper. This has been investigated using well established diagnostics including the Modular UHF Ionospheric Radar (MUIR) and Kodiak SuperDARN radars as well as Wideband SEE (WSEE). The measured data using these three diagnostics were compared to characterize the ionospheric parameters and study the plasma irregularities generated in the interaction region. Variation of the wideband/narrowband SEE features, SuperDARN echoes, and HF-enhanced ion lines (EHIL) were studied with pump power variation, pump frequency stepping near the third electron gyro-frequency (3fce) as well as changing beam angle relative to the magnetic zenith. In particular, electrostatic plasma waves and associated irregularities excited near the reflection resonance layer as well as the upper-hybrid resonance layer are investigated. The time evolution and growth rate of these irregularities are studied using the experimental observations. Close alignment of narrowband SEE (NSEE) with wideband SEE (WSEE) and EHIL was observed. SuperDARN radar echoes and WSEE also showed alignment as in previous investigations. Correlations between these three measurements underscore potential diagnostics by utilizing the NSEE spectrum to estimate ionospheric parameters such as electron temperature.

High Frequency Resolution TOA Analysis for ELF/VLFWave Generation Experiments at HAARP

NASA Astrophysics Data System (ADS)

Ruddle, J. D.; Moore, R. C.

2014-12-01

Modulated HF heating of the ionosphere in the presence of natural ionospheric current sources has been used as a method to generate electromagnetic ELF/VLF waves since the 1970's. In the ~1-5 kHz band, the amplitude and phase of the received ELF/VLF signal depends on the amplitude and phase of the conductivity modulation generated throughout the HF-heated ionospheric body, as well as on the signal propagation parameters (i.e., the attenuation and phase constants) between each of the current sources and the receiver. Recent signal processing advances have produced an accurate ELF/VLF time-of-arrival (TOA) analysis technique that differentiates line-of-sight and ionospherically-reflected signal components, determining the amplitude and phase of each component observed at the receiver. This TOA method requires a wide bandwidth (> 2.5 kHz) and therefore is relatively insensitive to the frequency-dependent nature of ELF/VLF wave propagation. In this paper, we present an improved ELF/VLF TOA method that is capable of providing high frequency resolution. The new analysis technique is applied to experimental observations of ELF/VLF signals generated by modulated heating at HAARP. We present measurements of the amplitude and phase of the received ELF/VLF signal as a function of frequency and compare the results with the predictions of an HF heating model.

Multi-hop Whistler-Mode ELF/VLF Signals and Triggered Emissions Excited by the HAARP HF Heater

DTIC Science & Technology

2004-12-28

distribution along the field line [ Angerami and Thomas, 1964] to infer the equatorial electron density Neq. This analysis revealed values of L ’ 4.9 and...the ELF/VLF receiver used on RV Tangaroa. References Angerami , J. J., and J. O. Thomas (1964), Studies of planetary atmospheres: 1. The distribution of

Power-Stepped HF Cross-Modulation Experiments: Simulations and Experimental Observations

NASA Astrophysics Data System (ADS)

Greene, S.; Moore, R. C.

2014-12-01

High frequency (HF) cross modulation experiments are a well established means for probing the HF-modified characteristics of the D-region ionosphere. The interaction between the heating wave and the probing pulse depends on the ambient and modified conditions of the D-region ionosphere. Cross-modulation observations are employed as a measure of the HF-modified refractive index. We employ an optimized version of Fejer's method that we developed during previous experiments. Experiments were performed in March 2013 at the High Frequency Active Auroral Research Program (HAARP) observatory in Gakona, Alaska. During these experiments, the power of the HF heating signal incrementally increased in order to determine the dependence of cross-modulation on HF power. We found that a simple power law relationship does not hold at high power levels, similar to previous ELF/VLF wave generation experiments. In this paper, we critically compare these experimental observations with the predictions of a numerical ionospheric HF heating model and demonstrate close agreement.

Stimulated Brillouin scatter in a magnetized ionospheric plasma.

PubMed

Bernhardt, P A; Selcher, C A; Lehmberg, R H; Rodriguez, S P; Thomason, J F; Groves, K M; McCarrick, M J; Frazer, G J

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f(CI)) or an electrostatic ion cyclotron (EIC) wave just above f(CI) can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.

IMPROVING SCIENCE EDUCATION AND CAREER OPPORTUNITIES IN RURAL ALASKA:The Synergistic Connection between Educational Outreach Efforts in the Copper Valley, Alaska.

NASA Astrophysics Data System (ADS)

Solie, D. J.; McCarthy, S.

2004-12-01

The objective of the High frequency Active Auroral Research Program (HAARP) Education Outreach is to enhance the science education opportunities in the Copper Valley region in Alaska. In the process, we also educate local residents about HAARP and its research. Funded jointly by US Air Force and Navy, HAARP is located at Gakona Alaska, a very rural region of central Alaska with a predominantly Native population. The main instrument at HAARP is a vertically directed, phased array RF transmitter which is primarily an ionospheric research tool, however, its geophysical research applications range from terrestrial to near-space. Research is conducted at HAARP in collaboration with scientists and institutions world-wide. The HAARP Education Outreach Program, run through the University of Alaska Geophysical Institute has been active for over six years and in that time has become an integral part of science education in the Copper Valley for residents of all ages. HAARP education outreach efforts are through direct involvement in local schools in the Copper River School District (CRSD) and the Prince William Sound Community College (PWSCC), as well as public lectures and workshops, and intern and student research programs. These outreach efforts require cooperation and coordination between the CRSD, PWSCC, the University of Alaska Fairbanks Physics Department and the NSF sponsored Alaska Native Science & Engineering Program (ANSEP) and HAARP researchers. The HAARP Outreach program also works with other organizations promoting science education in the region, such as the National Park Service (Wrangell- St. Elias National Park) and the Wrangell Institute for Science and Environment (WISE) a newly formed regional non-profit organization. We work closely with teachers in the schools, adapting to their needs and the particular scientific topic they are covering at the time. Because of time and logistic constraints, outreach visits to schools are episodic, occurring roughly four times a year. Even though the in-class time per year is not large, our experience suggests that a long term, multi-year connection enhances learning by the students. We coordinate with HAARP research campaigns so as to utilize the availability of top scientists for public lectures. We do not limit our scope to only ionospheric physics, but try to meet the demands and needs of the region as they arise. Less than two weeks after the November, 2002 Denali Fault Earthquake, we traveled to the villages most strongly effected by the quake and presented basic preliminary information about the quake (Sources: Alaska Earthquake Information Center, Alaska State Geological Survey & USGS). As a teachable moment it was unparalleled, but it was also an example of where even preliminary information on an event can truly help to calm people.

Optimizing an ELF/VLF Phased Array at HAARP

NASA Astrophysics Data System (ADS)

Fujimaru, S.; Moore, R. C.

2013-12-01

The goal of this study is to maximize the amplitude of 1-5 kHz ELF/VLF waves generated by ionospheric HF heating and measured at a ground-based ELF/VLF receiver. The optimization makes use of experimental observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) Observatory in Gakona, Alaska. During these experiments, the amplitude, phase, and propagation delay of the ELF/VLF waves were carefully measured. The HF beam was aimed at 15 degrees zenith angle in 8 different azimuthal directions, equally spaced in a circle, while broadcasting a 3.25 MHz (X-mode) signal that was amplitude modulated (square wave) with a linear frequency-time chirp between 1 and 5 kHz. The experimental observations are used to provide reference amplitudes, phases, and propagation delays for ELF/VLF waves generated at these specific locations. The presented optimization accounts for the trade-off between duty cycle, heated area, and the distributed nature of the source region in order to construct a "most efficient" phased array. The amplitudes and phases generated by modulated heating at each location are combined in post-processing to find an optimal combination of duty cycle, heating location, and heating order.

Lunar Radar Cross Section at Low Frequency

NASA Technical Reports Server (NTRS)

Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V.

2002-01-01

Recent bistatic measurements of the lunar radar cross-section have extended the spectrum to long radio wavelength. We have utilized the HF Active Auroral Research Program (HAARP) radar facility near Gakona, Alaska to transmit high power pulses at 8.075 MHz to the Moon; the echo pulses were received onboard the NASA/WIND spacecraft by the WAVES HF receiver. This lunar radar experiment follows our previous use of earth-based HF radar with satellites to conduct space experiments. The spacecraft was approaching the Moon for a scheduled orbit perturbation when our experiment of 13 September 2001 was conducted. During the two-hour experiment, the radial distance of the satellite from the Moon varied from 28 to 24 Rm, where Rm is in lunar radii.

Stimulated Brillouin Scatter in a Magnetized Ionospheric Plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernhardt, P. A.; Selcher, C. A.; Lehmberg, R. H.

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f{sub CI}) or an electrostatic ion cyclotron (EIC) wave just above f{sub CI} can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves aremore » excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.« less

Artificial Excitation of Schumann Resonance with HAARP

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Chang, C. L.

2014-12-01

We report results from the experiment aimed at the artificial excitation of extremely-low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance (typically, 7.5 - 8.0 Hz frequency range). Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated by the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range of the Schumann resonance, when the ionosphere has a strong F-layer and an electric field greater than 5 mV/m is present in the E-region.

Artificial Ionospheric Turbulence and Radio Wave Propagation (Sura - HAARP)

DTIC Science & Technology

2006-11-01

investigations of AIT features, which have allowed to establish dependences of low-frequency AIT properties on PW power, frequency, and polarization , on...that a powerful HF heater wave of ordinary polarization , injected vertically from the ground into the ionosphere F-region, gives rise to secondary...or in direct proportion to the value of striation k- vector ). Basing on experimental data considered above we can conclude that for both narrow

Determining Energy Distributions of HF-Accelerated Electrons at HAARP

DTIC Science & Technology

2015-11-18

altitude satellites , altitude- resolved side-view optical measurements of artificial airglow emissions combined with full ISR measurements of electron...for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data...3. DATES COVERED. Indicate the time during which the work was performed and the report was written, e.g., Jun 1997 - Jun 1998; 1-10 Jun 1996; May

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-01

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below the upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.

Experiments and theory on parametric instabilities excited in HF heating experiments at HAARP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, Spencer; Snyder, Arnold; Lee, M. C.

2014-06-15

Parametric instabilities excited by O-mode HF heater and the induced ionospheric modification were explored via HAARP digisonde operated in a fast mode. The impact of excited Langmuir waves and upper hybrid waves on the ionosphere are manifested by bumps in the virtual spread, which expand the ionogram echoes upward as much as 140 km and the downward range spread of the sounding echoes, which exceeds 50 km over a significant frequency range. The theory of parametric instabilities is presented. The theory identifies the ionogram bump located between the 3.2 MHz heater frequency and the upper hybrid resonance frequency and the bump below themore » upper hybrid resonance frequency to be associated with the Langmuir and upper hybrid instabilities, respectively. The Langmuir bump is located close to the upper hybrid resonance frequency, rather than to the heater frequency, consistent with the theory. Each bump in the virtual height spread of the ionogram is similar to the cusp occurring in daytime ionograms at the E-F2 layer transition, indicating that there is a small ledge in the density profile similar to E-F2 layer transitions. The experimental results also show that the strong impact of the upper hybrid instability on the ionosphere can suppress the Langmuir instability.« less

Excitation of Earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current

NASA Astrophysics Data System (ADS)

Field, E. C.; Bloom, R. M.

1993-05-01

In this report, the principal of reciprocity is used in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80 to 90 km. The highest efficiency occurs for a source altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 km.

Initial results of stimulated radiation measurements during the HAARP campaign of September 2017

NASA Astrophysics Data System (ADS)

Yellu, A. D.; Scales, W. A.; Mahmoudian, A.; Siefring, C.; Bernhardt, P.

2018-02-01

Initial results of stimulated electromagnetic radiation observed during an ionosphere heating experiment conducted at the High-Frequency Active Auroral Program (HAARP) facility are reported. The frequency of the pump wave used in the heating is in the neighborhood of the third harmonic of the electron cyclotron frequency, and of interest are simulated electromagnetic emissions (SEEs) within ? kHz of the heating frequency known as narrowband SEE (NSEE) and the commonly known wideband SEE (WSEE) which occur within ? kHz of the pump wave frequency. With the transmit power maintained at maximum, and all other conditions of the experiment invariable, the characteristics of NSEE and WSEE as time progresses from the time the transmitter is switched on are detailed in the results. The dependence of the characteristics of the NSEE and WSEE with temporal evolution into the heating cycle are observed to be fundamentally different.

12. Hard HF transmitter antenna, view toward west. Lyon ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. Hard HF transmitter antenna, view toward west. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

Artificial ionospheric layers during pump frequency stepping near the 4th gyroharmonic at HAARP.

PubMed

Sergeev, E; Grach, S; Shindin, A; Mishin, E; Bernhardt, P; Briczinski, S; Isham, B; Broughton, M; LaBelle, J; Watkins, B

2013-02-08

We report on artificial descending plasma layers created in the ionosphere F region by high-power high-frequency (HF) radio waves from High-frequency Active Auroral Research Program at frequencies f(0) near the fourth electron gyroharmonic 4f(ce). The data come from concurrent measurements of the secondary escaping radiation from the HF-pumped ionosphere, also known as stimulated electromagnetic emission, reflected probing signals at f(0), and plasma line radar echoes. The artificial layers appeared only for injections along the magnetic field and f(0)>4f(ce) at the nominal HF interaction altitude in the background ionosphere. Their average downward speed ~0.5 km/s holds until the terminal altitude where the local fourth gyroharmonic matches f(0). The total descent increases with the nominal offset f(0)-4f(ce).

First demonstration of HF-driven ionospheric currents

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Chang, C.-L.; Labenski, J.; Wallace, T.

2011-10-01

The first experimental demonstration of HF driven currents in the ionosphere at low ELF/ULF frequencies without relying in the presence of electrojets is presented. The effect was predicted by theoretical/computational means in a recent letter and given the name Ionospheric Current Drive (ICD). The effect relies on modulated F-region HF heating to generate Magneto-Sonic (MS) waves that drive Hall currents when they reach the E-region. The Hall currents inject ELF waves into the Earth-Ionosphere waveguide and helicon and Shear Alfven (SA) waves in the magnetosphere. The proof-of-concept experiments were conducted using the HAARP heater in Alaska under the BRIOCHE program. Waves between 0.1-70 Hz were measured at both near and far sites. The letter discusses the differences between ICD generated waves and those relying on modulation of electrojets.

Investigation of Third Gyro-harmonic Heating at HAARP Using Stimulated Radio Emissions, the MUIR and SuperDARN Radars

NASA Astrophysics Data System (ADS)

Mahmoudian, Alireza; Bernhardt, Paul; Ruohoniemi, J. Michael; Isham, Brett; Watkins, Brenton; Scales, Wayne

2016-07-01

Use of high frequency (HF) heating experiments has been extended in recent years as a useful methodology for plasma physicists wishing to remotely study the properties and behavior of the ionosphere as well as nonlinear plasma processes. Our recent work using high latitude heating experiments has lead to several important discoveries that have enabled assessment of active geomagnetic conditions, determination of minor ion species and their densities, ion mass spectrometry, electron temperature measurements in the heating ionosphere, as well a deeper understanding of physical processes associated with electron acceleration and formation of field aligned irregularities. The data recorded during two campaigns at HAARP in 2011 and 2012 will be presented. Several diagnostic instruments have been used to detect HAARP heater-generated ionospheric irregularities and plasma waves. These diagnostics include an ionosonde, MUIR (Modular UHF Ionospheric Radar at 446 MHz), SuperDARN HF backscatter radar and ground-based SEE receivers. Variation of the wideband/ narrowband SEE features, SuperDARN echoes, and enhanced ion lines were studied with pump power variation, pump frequency stepping near 3fce as well as changing beam angle relative to the magnetic zenith. In particular, formation of field-aligned irregularities (FAIs) and upper hybrid (UH) waves through oscillating two-stream instability (OSTI) and resonance instability is studied. During heating, Narrowband SEE (NSEE) showed enhancements that correlated with the enhanced MUIR radar ion lines. IA MSBS (Magnetized Stimulated Brillouin Scatter) lines are much narrower than Wideband SEE (WSEE) lines and as a result electron temperature calculated using NSEE line offset has potential to be more accurate. This technique may therefore complement the electron temperature calculation using ISR spectra. Strength of IA MSBS lines correlate with EHIL in the MUIR spectrum during HF pump frequency variation near 3fce. Therefore, NSEE could be used for similar diagnostic information, particularly temperature assessment during heating. More detailed physics-based modeling of such SEE is expected to provide further diagnostic information/capabilities. This work has demonstrated the tremendous future potential of Narrowband SEE (NSEE) as a powerful untapped ionospheric diagnostic which could provide complementary measurements for locations that ISR facilities are not available or as a complementary measurement for the waves and irregularities that cannot be observed by ISR.

Excitation of earth-ionosphere waveguide in the ELF and lower VLF bands by modulated ionospheric current. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Field, E.C.; Bloom, R.M.

1993-05-21

In this report the authors use the principal of reciprocity in conjunction with a full-wave propagation code to calculate ground-level fields excited by ionospheric currents modulated at frequencies between 50 and 100 Hz with HF heaters. Their results show the dependence on source orientation, altitude, and dimension and therefore pertain to experiments using the HIPAS or HAARP ionospheric heaters. In the end-fire mode, the waveguide excitation efficiency of an ELF HED in the ionosphere is up to 20 dB greater than for a ground-based antenna, provided its altitude does not exceed 80-to-90 km. The highest efficiency occurs for a sourcemore » altitude of around 70 km; if that altitude is raised to 100 km, the efficiency drops by about 20 dB in the day and 10 dB at night. That efficiency does not account for the greater conductivity modulation that might be achieved at altitudes greater than 70 km, however. The trade-off between the altitude dependencies of the excitation efficiency and maximum achievable modulation depends on the ERP of the HF heater, the optimum altitude increasing with increasing ERP. For HIPAS the best modulation altitude is around 70 km, whereas for HAARP there might be marginal value in modulating at attitudes as high as 100 Km. Ionospheric modification, Ionospheric currents, Ionospheric heating.« less

High Latitude Scintillation Monitoring at UHF with the COMMX Experiment on TACSat4

NASA Astrophysics Data System (ADS)

Bernhardt, P. A.; Siefring, C. L.; Akins, K.; Nurnberger, M.

2013-12-01

UHF Beacon Transmissions at 253 MHz have provided high latitude scintillation monitoring from Gakona Alaska using the COMMX instrument on TACSat4. TACSat4 was constructed by the Naval Research Laboratory and was launched in September 2011 as an experimental communications satellite. Ground UHF transmissions are uplinked to TACSat4 using the 4 meter diameter antenna deployed to view the earth. These signals are coherently translated to other UHF frequency to be rebroadcast to the ground. Scintillation monitoring is achieved by taking the 401.25 MHz signals from ground DORIS beacons located in Cold Bay, Alaska; Yellowknife, Canada; Kauai, Hawaii; and Soccoro Island, Mexico. These signals are translated to 253 MHz and broadcast with the 4 meter antenna pointed to the UHF receiver located at Gakona, Alaska. The satellite antenna gain is 18 dB in this UHF band and the transmitter power is 2 Watts. The satellite is in an elliptical orbit with an inclination of 63 degrees and a perigee of 12,000 km. Doppler frequency shifts allow separation of each uplink from the ground DORIS beacons. This new scintillation monitoring system has been used to detect natural and artificial field aligned irregularity effects on the amplitude and phase of UHF carriers where typical scintillation amplitudes are 2dB or less. Using the HAARP transmitter in Alaska, TACSat4 was used to discover the artificial ionization clouds produce scintillation with as much as 16 dB and amplitude indices S4 greater than unity. This is the first demonstration of significant effects on radio scintillations using high power HF radio waves to disturb the ionosphere.

Study of HF-induced plasma turbulence by SEE and ISR technique during 2011 HAARP experimental campaign

NASA Astrophysics Data System (ADS)

Grach, Savely; Bernhardt, Paul; Sergeev, Evgeny; Shindin, Alexey; Broughton, Matt; Labelle, James; Bricinsky, Stanley; Mishin, Evgeny; Isham, Brett; Watkins, Brenton

A concise review of the results of the 20 March - 4 April 2011 experimental campaign at the HAARP heating facility, Gakona, Alaska is presented. The campaign goals were to study the physical processes that determine the interaction of high-power HF radio waves with the F-region ionosphere. The stimulated electromagnetic emission (SEE) observational sites A/B/C were located along the magnetic meridian to the south of the HAARP facility at about 11/83/113 km distant. Site A (B) was nearly under the region during injections at vertical (Magnetic Zenith, MZ). Enhanced plasma line (PL) radar echoes were measured by the modular UHF incoherent scatter radar (MUIR) located at HAARP. Specially designed 'diagnostic' regimes of the pump wave radiation were used to account for the characteristic times of the excitation and fading of the plasma waves (Delta t_w ˜ 1-10 ms) and small-scale field-aligned irregularities (FAI, Delta t_{fai} ˜ 1-10 s). They include mainly (I) alternation low-duty cycles consisting of short (a few Delta t_w) pulses with long (Delta t_{fai}) pauses between them and high duty cycles, i.e. long injection pulses (≫ t_w) with a short pauses of 20-30 ms. The low-duty regime is aimed to study the excited Langmuir turbulence and at to specify the evolution of FAI and their scale-lengths related to different SEE spectral features. The main objective of the high-duty regime is to explore the excitation and fading of upper-hybrid and electron Bernstein plasma waves, with FAI fixed. (II) Concurrent injection of the pump wave f_0 in the regime I, and another wave at a frequency f_1≠q f_0 in the low duty cycle. Since these waves reflect/refract at different altitudes, the altitudinal distribution of FAI can be obtained. (III) Fast (within some seconds) sweeping the pump frequency about electron gyroharmonics s f_c (s=2,3,4) in order to determine the contribution of various nonlinear interaction processes to the excitation of the HF part of the pump-excited turbulence as a function of f_0-sf_c at the fixed FAI and background ionosphere parameters. The main results describe (1) the rise and fall of Langmuir turbulence after the start of pumping, which reveal the notable difference in the SEE spectra and reflected PW signals at different receiving cites and the energy transfer of the Langmuir waves over the spectrum; (2) the development of descending layers of artificial ionization during high-duty cycle injections at MZ; (3) the PL generation during the fast sweeping at MZ near the altitude where the PW frequency is close to local multiple electron gyro-frequency; (4) the discovery of a new SEE spectral feature at frequencies below the PW frequency by 50-150 kHz, coined the Broad Downshifted Emission; (5) the specification of the SEE spectra near the second electron gyroharmonic.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noor, Fatimah A., E-mail: fatimah@fi.itb.ac.id; Iskandar, Ferry; Abdullah, Mikrajuddin

In this paper, we discuss the electron transmittance and tunneling current in high-k-based-MOS capacitors with trapping charge by including the off-diagonal effective-mass tensor elements and the effect of coupling between transverse and longitudinal energies represented by an electron velocity in the gate. The HfSiO{sub x}N/SiO{sub 2} dual ultrathin layer is used as the gate oxide in an n{sup +} poly- Si/oxide/Si capacitor to replace SiO{sub 2}. The main problem of using HfSiO{sub x}N is the charge trapping formed at the HfSiO{sub x}N/SiO{sub 2} interface that can influence the performance of the device. Therefore, it is important to develop a modelmore » taking into account the presence of electron traps at the HfSiO{sub x}N/SiO{sub 2} interface in the electron transmittance and tunneling current. The transmittance and tunneling current in n{sup +} poly- Si/HfSiO{sub x}N/trap/SiO2/Si(100) capacitors are calculated by using Airy wavefunctions and a transfer matrix method (TMM) as analytical and numerical approaches, respectively. The transmittance and tunneling current obtained from the Airy wavefunction are compared to those computed by the TMM. The effects of the electron velocity on the transmittance and tunneling current are also discussed.« less

HF-induced airglow structure as a proxy for ionospheric irregularity detection

NASA Astrophysics Data System (ADS)

Kendall, E. A.

2013-12-01

The High Frequency Active Auroral Research Program (HAARP) heating facility allows scientists to test current theories of plasma physics to gain a better understanding of the underlying mechanisms at work in the lower ionosphere. One powerful technique for diagnosing radio frequency interactions in the ionosphere is to use ground-based optical instrumentation. High-frequency (HF), heater-induced artificial airglow observations can be used to diagnose electron energies and distributions in the heated region, illuminate natural and/or artificially induced ionospheric irregularities, determine ExB plasma drifts, and measure quenching rates by neutral species. Artificial airglow is caused by HF-accelerated electrons colliding with various atmospheric constituents, which in turn emit a photon. The most common emissions are 630.0 nm O(1D), 557.7 nm O(1S), and 427.8 nm N2+(1NG). Because more photons will be emitted in regions of higher electron energization, it may be possible to use airglow imaging to map artificial field-aligned irregularities at a particular altitude range in the ionosphere. Since fairly wide field-of-view imagers are typically deployed in airglow campaigns, it is not well-known what meter-scale features exist in the artificial airglow emissions. Rocket data show that heater-induced electron density variations, or irregularities, consist of bundles of ~10-m-wide magnetic field-aligned filaments with a mean depletion depth of 6% [Kelley et al., 1995]. These bundles themselves constitute small-scale structures with widths of 1.5 to 6 km. Telescopic imaging provides high resolution spatial coverage of ionospheric irregularities and goes hand in hand with other observing techniques such as GPS scintillation, radar, and ionosonde. Since airglow observations can presumably image ionospheric irregularities (electron density variations), they can be used to determine the spatial scale variation, the fill factor, and the lifetime characteristics of irregularities. Telescopic imaging of airglow is a technique capable of simultaneously determining the properties of ionospheric irregularities at decameter resolution over a range of several kilometers. The HAARP telescopic imager consists of two cameras, a set of optics for each camera, and a robotic mount that supports and orients the system. The camera and optics systems are identical except for the camera lenses: one has a wide-angle lens (~19 degrees) and the other has a telescopic lens (~3 degrees). The telescopic imager has a resolution of ~20 m in the F layer and ~10 m in the E layer, which allows the observation of decameter- and kilometer-scale features. Analysis of telescopic data from HAARP campaigns over the last five years will be presented.

Characterization of Ionosphere Waveguide Propagation by Monitoring HAARP HF Transmissions in Antarctica

DTIC Science & Technology

2015-04-17

hhh hhhh hh (7а)  .)cos(cos)sincoscos( cos)coscossin( cos 1sin 0 2)(22 0 2)( 00 )( 00 )()( 00 )( 00)(22 0 2 0 )( 2,1         s x i...z i xz si z i xxs xz s hhhh hhh hh   7b) Here the top sign stands for )(1 s , while the lower sign stands for )(2 s . It is also taken into

First artificial periodic inhomogeneity experiments at HAARP

NASA Astrophysics Data System (ADS)

Hysell, D. L.; McCarrick, M. J.; Fallen, C. T.; Vierinen, J.

2015-03-01

Experiments involving the generation and detection of artificial periodic inhomogeneities have been performed at the High Frequency Active Auroral Research Program (HAARP) facility. Irregularities were created using powerful X-mode HF emissions and then probed using short (10 μs) X- and O-mode pulses. Reception was performed using a portable software-defined receiver together with the crossed rhombic antenna from the local ionosonde. Echoes were observed reliably between about 85 and 140 km altitude with signal-to-noise ratios as high as about 30 dB. The Doppler shift of the echoes can be associated with the vertical neutral wind in this altitude range. Small but persistent Doppler shifts were observed. The decay time constant of the echoes is meanwhile indicative of the ambipolar diffusion coefficient which depends on the plasma temperature, composition, and neutral gas density. The measured time constants appear to be consistent with theoretical expectations and imply a methodology for measuring neutral density profiles. The significance of thermospheric vertical neutral wind and density measurements which are difficult to obtain using ground-based instruments by other means is discussed.

Upper Hybrid Effects in Artificial Ionization

NASA Astrophysics Data System (ADS)

Papadopoulos, K.; Eliasson, B. E.

2014-12-01

A most fascinating result of recent ionospheric experiments has been the discovery of artificial ionization by Pedersen et al. (GRL, 37, L02106, 2010). The Artificial Ionospheric Layers (AIL) were the result of F-region O-mode HF irradiation using the HAARP ionospheric heater operating at 3.6 MW power. As demonstrated by Eliasson et al. (JGR, 117, A10321, 2012) the physics controlling the observed phenomenon and its threshold can be summarized as: " Collisional ionization due to high energy (~ 20 eV) electron tails generated by the interaction of strong Langmuir turbulence with plasma heated at the upper hybrid resonance and transported at the reflection height". The objective of the current presentation is to explore the role of the upper hybrid heating in the formation of AIL and its implications to future experiments involving HF heaters operating in middle and equatorial latitudes.

First results from the energetic particle instrument on the OEDIPUS-C sounding rocket

NASA Astrophysics Data System (ADS)

Gough, M. P.; Hardy, D. A.; James, H. G.

The Canadian / US OEDIPUS-C rocket was flown from the Poker Flat Rocket Range November 6th 1995 as a mother-son sounding rocket. It was designed to study auroral ionospheric plasma physics using active wave sounding and prove tether technology. The payload separated into two sections reaching a separation of 1200m along the Earth's magnetic field. One section included a frequency stepped HF transmitter and the other included a synchronised HF receiver. Both sections included Energetic Particle Instruments, EPI, stepped in energy synchronously with the transmitter steps. On-board EPI particle processing in both payloads provided direct measurements of electron heating, wave-particle interactions via particle correlators, and a high resolution measurement of wave induced particle heating via transmitter synchronised fast sampling. Strong electron heating was observed at times when the HF transmitter frequency was equal to a harmonic of the electron gyrofrequency, f_ce, or equal to the upper hybrid frequency, f_uh.

Bistatic radar sea state monitoring

NASA Technical Reports Server (NTRS)

Ruck, G. T.; Barrick, D. E.; Kaliszewski, T.

1972-01-01

Bistatic radar techniques were examined for remote measurement of the two-dimensional surface wave height spectrum of the ocean. One technique operates at high frequencies (HF), 3-30 MHz, and the other at ultrahigh frequencies (UHF), approximately 1 GHz. Only a preliminary theoretical examination of the UHF technique was performed; however the principle underlying the HF technique was demonstrated experimentally with results indicating that an HF bistatic system using a surface transmitter and an orbital receiver would be capable of measuring the two-dimensional wave height spectrum in the vicinity of the transmitter. An HF bistatic system could also be used with an airborne receiver for ground truth ocean wave spectrum measurements. Preliminary system requirements and hardware configurations are discussed for both an orbital system and an aircraft verification experiment.

Generation of whistler waves by continuous HF heating of the upper ionosphere

NASA Astrophysics Data System (ADS)

Vartanyan, A.; Milikh, G. M.; Eliasson, B. E.; Sharma, A.; Chang, C.; Parrot, M.; Papadopoulos, K.

2013-12-01

We report observations of VLF waves by the DEMETER satellite overflying the HAARP facility during ionospheric heating experiments. The detected VLF waves were in the range 8-17 kHz and coincided with times of continuous heating. The experiments indicate whistler generation due to conversion of artificial lower hybrid waves to whistlers on small scale field-aligned plasma density striations. The observations are compared with theoretical models, taking into account both linear and nonlinear processes. Implications of the mode conversion technique on VLF generation with subsequent injection into the radiation belts to trigger particle precipitation are discussed.

Artificial ionosphere layers for pumping-wave frequencies near the fourth electron gyroharmonic in experiments at the HAARP facility

NASA Astrophysics Data System (ADS)

Grach, S. M.; Sergeev, E. N.; Shindin, A. V.; Mishin, E. V.; Watkins, B.

2014-02-01

In this paper we consider the action (in the magnetic-zenith direction) of powerful high frequency (HF) radiation of ordinary polarization on the ionosphere F region. We deal with frequencies f 0 > 4 f ce ( f ce is the electron cyclotron frequency) of 1.7 GW equivalent radiated power. This action results in the appearance in the ionosphere of an artificial ionization layer. The layer descends with respect to the basic (unperturbed) layer at a rate of ˜500 m s-1 down to the altitude, where f 0 ≈ 4 f ce .

Artificial excitation of ELF waves with frequency of Schumann resonance

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Guido, T.; Tulegenov, B.; Labenski, J.; Chang, C.-L.

2014-11-01

We report results from the experiment aimed at the artificial excitation of extremely low-frequency (ELF) electromagnetic waves with frequencies corresponding to the frequency of Schumann resonance. Electromagnetic waves with these frequencies can form a standing pattern inside the spherical cavity formed by the surface of the Earth and the ionosphere. In the experiment the ELF waves were excited by heating the ionosphere with X-mode HF electromagnetic waves generated at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. The experiment demonstrates that heating of the ionosphere can excite relatively large-amplitude electromagnetic waves with frequencies in the range 7.8-8.0 Hz when the ionosphere has a strong F layer, the frequency of the HF radiation is in the range 3.20-4.57 MHz, and the electric field greater than 5 mV/m is present in the ionosphere.

Further Investigations of Ionospheric Total Electron Content and Scintillation Effects on Transionospheric Radiowave Propagation

DTIC Science & Technology

1998-02-12

HAARP ). 14. SUBJECT TERMS Global Positioning System (GPS), High Frequency Active Auroral Research Program ( HAARP ), ionosphere, radiowave...Scintillation Simulation 23 4.10 Automated Calibrations 23 5. HAARP Activities 24 5.1 Development of HAARP Diagnostics 24 5.2 Facilitation of... HAARP Operations and Broader Scientific Collaborations 27 5.3 Public Relations 28 6. Publications 30 References 30 Acronyms and Initials 30 Appendix

Telescopic Imaging of Heater-Induced Airglow at HAARP

DTIC Science & Technology

2007-01-01

03-01-2007 Final1 10-09-2003 - 10-09-2006 4. TITLE AND SUBTITLE Ba. CONTRACT NUMBER Telescopic Imaging of Heater-Induced Airglow at HAARP N00014-03-1... HAARP to optically measure fine structure in the ionosphere and to study airglow sources. In the presence of aurora and a strong blanketing E layer... HAARP was modulated at intervals of several seconds. For several cycles, small bright airglow spots were observed whenever HAARP was on. These spots

Polar azimuth diversity HF propagation experiment

NASA Astrophysics Data System (ADS)

Baker, Kurt A.; Haines, D. M.; Weijers, Bertus

1986-03-01

Presented are the results of an HF Azimuth Diversity Propagation Experiment conducted by RADC over several paths, transauroral and polar, separated in azimuth by 30, 70, and 100 degrees, as part of the RADC Adaptive HF Propagation Program. The data presented give the occurrence of several ionospheric characteristics important to the operation of HF networks in a disturbed environment. The analysis was performed on data collected during the four seasonal periods to obtain statistical samples representative of each season under slightly disturbed as well as quiet conditions. The system used to collect the data was a network of three chirpsounder transmitters and one receiver, each sweeping over a frequency range of 2 to 30 MHz, once every five minutes. The transmitters were located at Ava, N.Y., Grand Forks, N. Dak., and Barter Island, Alaska. The receiving system was located at Thule Air Base, Greenland.

USCG HF SITOR

Science.gov Websites

broadcasts from Boston sharing the same transmitters. See table below for station locations and schedules meteorological observations. Boston(NMF) HF SITOR (NBDP) Broadcast Schedule 6314, 8416.5, 12579 kHz 0140Z3 8416.5

On the Additional Absorption of Radio Emission from Discrete Cosmic Sources Under HF Modification of the Lower Ionosphere

NASA Astrophysics Data System (ADS)

Bezrodny, V. G.; Charkina, O. V.; Yampolski, Yu. M.

2015-12-01

The possibilities of modification of a weakly ionized plasma are investigated theoretically and experimentally within different electron density behavior models. The dependence of the additional absorption of radiation of discreet cosmic sources Cassiopeia A and Cygnus A in the artificially disturbed ionospheric D-region on the amplitude of heating signal during the special measuring campaigns of February and October 2008 has been analyzed. The ionosphere has been modified with using the world most powerful HAARP heater, Alaska, USA. The 64 beam riometer located in the immediate vicinity of the heater was used as the recording system.

Thermal response of the F region ionosphere in artificial modification experiments by HF radio waves

NASA Technical Reports Server (NTRS)

Mantas, G. P.; Lahoz, C. H.; Carlson, H. C., Jr.

1981-01-01

The thermal response of the nighttime F region ionosphere to local heating by HF radio waves has been observed with the incoherent scatter radar at Arecibo, Puerto Rico. The observations consist of high-resolution space and time variation of the electron temperature as a high-power HF transmitter is switched on and off with a period 240 s. As soon as the HF transmitter is turned on, the electron temperature begins to rise rapidly in a narrow altitude region near 300 km, below the F2 layer peak. The electron temperature perturbation subsequently spreads over a broader altitude region. The observations are compared with the anticipated thermal response of the ionosphere based on numerical solutions of the coupled time-dependent heat conduction equations for the electron and composite ion gases and are found to be in good agreement over the entire altitude region covered by the observations.

Optimizing ELF/VLF generation via HF heating utilizing beam motion

NASA Astrophysics Data System (ADS)

Cohen, M. B.; Inan, U. S.; Lehtinen, N. G.; Golkowski, M. A.

2008-12-01

ELF/VLF (300 Hz - 30 kHz) waves are difficult to generate with conventional antennae due to their extraordinary long wavelengths, and the good conductance of the Earth at these frequencies. Recently, ELF and VLF waves have been generated using HF (3-10 MHz) heating of the lower ionosphere, in the presence of natural currents such as the auroral electrojet, which modulates the ionospheric conductivity and therefore turns the lower ionosphere into a large radiating element. The recently upgraded HAARP facility, near Gakona Alaska, utilizes 3.6 MW of HF power, along with an unprecedented ability to steer the HF heating beam over a large area extremely rapidly. Since the completion of the upgrade in 2007, the first successful implementation of techniques such as geometric modulation [Cohen et al. 2008, Borisov et al. 1998], and beam painting [Papadopoulos et al. 1989] have occurred. These results have shown as much as 7-11 dB improvement in the signal strengths, as well as the first ability to direct ELF/VLF signals via an unprecedented ELF/VLF phased array. Here, we use a combination of experimental and theoretical investigations to discuss the optimization of ELF/VLF generation via HF heating, including the effect of HF and ELF frequency on the amplitude and the directional pattern for various generation techniques. The experimental observations occur over an array of receivers across Alaska. The theoretical formulation utilizes a 3D model of the HF heating and subsequent electron cooling processes, leading to spatial structure of modulated ionospheric conductivities, the results of which are input into a model of ELF/VLF propagation in the Earth-ionosphere waveguide.

Vlasov Simulations of Ionospheric Heating Near Upper Hybrid Resonance

NASA Astrophysics Data System (ADS)

Najmi, A. C.; Eliasson, B. E.; Shao, X.; Milikh, G. M.; Papadopoulos, K.

2014-12-01

It is well-known that high-frequency (HF) heating of the ionosphere can excite field- aligned density striations (FAS) in the ionospheric plasma. Furthermore, in the neighborhood of various resonances, the pump wave can undergo parametric instabilities to produce a variety of electrostatic and electromagnetic waves. We have used a Vlasov simulation with 1-spatial dimension, 2-velocity dimensions, and 2-components of fields, to study the effects of ionospheric heating when the pump frequency is in the vicinity of the upper hybrid resonance, employing parameters currently available at ionospheric heaters such as HAARP. We have found that by seeding theplasma with a FAS of width ~20% of the simulation domain, ~10% depletion, and by applying a spatially uniform HF dipole pump electric field, the pump wave gives rise to a broad spectrum of density fluctuations as well as to upper hybrid and lower hybrid oscillating electric fields. We also observe collisionless bulk-heating of the electrons that varies non-linearly with the amplitude of the pump field.

Geometric Aspects of Artificial Ionospheric Layers Driven by High-Power HF-Heating

NASA Astrophysics Data System (ADS)

Milikh, G. M.; Eliasson, B.; Shao, X.; Djordjevic, B.; Mishin, E. V.; Zawdie, K.; Papadopoulos, K.

2013-12-01

We have generalized earlier developed multi-scale dynamic model for the creation and propagation of artificial plasma layers in the ionosphere [Eliasson et al, 2012] by including two dimensional effects in the horizontal direction. Such layers were observed during high-power high frequency HF heating experiments at HAARP [Pedersen et al., 2010]. We have numerically investigated the importance of different angles of incidence of ordinary mode waves on the Langmuir turbulence and the resulting electron acceleration that leads to the formation of artificial ionospheric layers. It was shown that the most efficient electron acceleration and subsequent ionization is obtained at angles between magnetic zenith and the vertical, where strong Langmuir turbulence dominates over weak turbulence. A role played by the heating wave propagation near caustics was also investigated. Eliasson, B. et al. (2012), J. Geophys. Res. 117, A10321, doi:10.1029/2012JA018105. Pedersen, T., et al. (2010), Geophys. Res. Lett., 37, L02106, doi:10.1029/2009GL041895.

The WIND-HAARP-HIPAS Interferometer Experiment

DTIC Science & Technology

1999-04-22

Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6750--99-8349 The WIND- HAARP -HIPAS Interferometer Experiment P. RODRIGUEZ AND M. J...1999 3. REPORT TYPE AND DATES COVERED Interim Report 4. TITLE AND SUBTITLE The WIND- HAARP -HIPAS Interferometer Experiment 5. FUNDING NUMBERS JO...frequency transmitting facilities in a bistatic, interferometer mode. The HAARP and HIPAS facilities in Alaska radiated at 4525 kHz with total combined

Full-Wave Radio Characterization of Ionospheric Modification at HAARP

DTIC Science & Technology

2015-07-26

Full-Wave Radio Characterization of Ionospheric Modification at HAARP We have studied electrostatic and electromagnetic turbulence stimulated by...radio receivers at HAARP in Alaska, and ground-based radio receivers, incoherent scatter radars, and in-situ measurements from Canadian, ESA, and Polish...363255 San Juan, PR 00936 -3255 31-May-2015 ABSTRACT Final Report: Full-Wave Radio Characterization of Ionospheric Modification at HAARP Report Title We

An Artificial Particle Precipitation Technique Using HAARP-Generated VLF Waves

DTIC Science & Technology

2006-11-02

AFRL-VS-HA-TR-2007-1021 An Artificial Particle Precipitation Technique Using HAARP -Generated VLF Waves O o o r- Q M. J. Kosch T. Pedersen J...Artificial Particle Precipitation Technique Using HAARP Generated VLF Waves. 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62101F...model. The frequency-time modulated VLF wave patterns have been successfully implemented at the HAARP ionospheric modification facility in Alaska

Radio Receiver Instrument (RRI) ePOP transionospheric observations from an HF transmitter in Ottawa (45N, 75W)

NASA Astrophysics Data System (ADS)

Hussey, G. C.; Danskin, D. W.; Gillies, R. G.; James, H. G.; Yau, A. W.; Hird, F. C.; Fairbairn, D. T.

2016-12-01

A ground-based HF transmitter operating at 10.422 MHz in Ottawa, Canada (45.4N, 75.6W) was the radio source for reception by the satellite-based Radio Receiver Instrument (RRI) for 5 passes in late April, 2016. The RRI is one of eight instruments on the enhanced Polar Outflow Probe (ePOP) scientific payload portion of the CSA (Canadian Space Agency) CASSIOPE (Cascade Demonstrator Small-Sat and Ionospheric Polar Explorer) satellite mission launched in September, 2013. The crossed-dipole configuration of the RRI allows for complete polarization observations. Initial analysis of the passes indicates reception of a highly polarized signal. South of the transmitter the signal clearly exhibits Faraday rotation of an essentially linearly polarized radio wave in agreement with modeling by Gillies et al. [2007]. This propagation is characterized as quasi-longitudinal (QL) by the Appleton-Hartree equation (electromagnetic wave propagation in a cold magnetized plasma) as the radio waves travel in a direction more along the magnetic field of the Earth. When the satellite moves north of the Ottawa transmitter the radio wave propagation transitions into quasi-transverse (QT). The data indicates favoring circular polarization dependent on the geometry with respect to the transmitter. Surprisingly the Faraday rotation effect is still very pronounced reversing in direction roughly 1000 km north of the transmitter. The model of Gillies et al. [2007] has been extended to explain these observations. This is the first direct observation, by polarimetry, of HF radio wave propagation in near-Earth space plasmas.Gillies, R.G., G.C. Hussey, H.G. James, G.J. Sofko, and D. Andre, Modelling and observation of transionospheric propagation results from ISIS II in preparation for ePOP, Ann. Geophys. 25, 87-97, 2007.

Solar Radiation Alert System

DTIC Science & Technology

2009-03-01

18 December 2007). 19. HAARP , The Hgh Frequency Actve Auroral Research Program. Glossary of Solar and Geophysical Terms. Avalable at...www.haarp.alaska.edu/ haarp /glos.html (accessed: 4 September 2007). 13 20. IZMIRAN. Pushkov Insttute of Terrestral Mag- netsm, Ionosphere and Radowave

Investigations of the Nature and Behavior of Plasma-Density Disturbances That May Impact GPS and Other Transionospheric Systems

DTIC Science & Technology

2002-10-31

association with the High-frequency Active Auroral Research Program ( HAARP ). In addition to a classic riometer and a GPS Total Electron Content (TEC...sensor previously operating at the HAARP site, NWRA also operates a set of Transit receivers for measurements of TEC and scintillation at VHF and UHF...supplementing the receiver at HAARP with a receiver north of the site and an additional receiver installed south of the HAARP site.

Characterization of the Auroral Electrojet and the Ambient and Modified D Region for HAARP Using Long-Path VLF Diagnostics

DTIC Science & Technology

2001-03-15

order to characterize the auroral electrojet and the ambient and modified D-region directly above and near the HAARP (High Frequency Active Auroral...near the HAARP facility and along the west coast of Alaska. In addition in order to characterize the auroral electrojet on a continental scale and to...United States and Canada. Data from the complete array of D-region diagnostic systems was acquired during a number of Fall and Spring HAARP campaigns

A Comparison of Science and Technology Funding for DoD’s Space and Nonspace Programs

DTIC Science & Technology

2008-01-15

Artificial intelligence for HAARP Multispectral signature libraries Environmental conditions that Ionospheric prediction HAARP Weather software for...Hardware and software for solar HAARP Electromagnetic interference for Plasma theory in the space Subproject details were not available Subproject

Equator and High-Latitude Ionosphere-to-Magnetosphere Research

DTIC Science & Technology

2010-12-04

characterizing plasma velocity profile in the heated region above HAARP has been clearly established. Specification of D region absorption from Digisonde...Electron density profile, Ground truth, Cal/Val, Doppler skymap, HAARP , Plasma velocity profile, Ionogram autoscaling, D region absorption...2  3  HAARP INVESTIGATIONS ............................................................................ 5  3.1

Handling Nonlinearities in ELF/VLF Generation Using Modulated Heating at HAARP

NASA Astrophysics Data System (ADS)

Jin, G.; Spasojevic, M.; Cohen, M.; Inan, U. S.

2011-12-01

George Jin Maria Spasojevic Morris Cohen Umran Inan Stanford University Modulated HF heating of the D-region ionosphere near the auroral electrojet can generate extremely low frequency (ELF) waves in the kilohertz range. This process is nonlinear and generates harmonics at integer multiples of the ELF modulation frequency. The nonlinear distortion has implications for any communications applications since the harmonics contain a substantial fraction of the signal power and use up bandwidth. We examine two techniques for handling the nonlinearity. First we modulate the HF heating with a non-sinusoidal envelope designed to create a sinusoidal change in the Hall conductivity at a particular altitude in the ionosphere to minimize any generated harmonics. The modulation waveform is generated by inverting a numerical HF heating model, starting from the desired conductivity time series, and obtaining the HF power envelope that will result in that conductivity. The second technique attempts to use the energy in the harmonics to improve bit error rates when digital modulation is applied to the ELF carrier. In conventional quadrature phase-shift keying (QPSK), where a ELF carrier is phase-shifted by 0°, 90°, 180°, and 270° in order to transmit a pair of bits, the even harmonics cannot distinguish between the four possible shifts. By using different phase values, all the energy in the harmonics can contribute to determining the phase of the carrier and thus improve the bit error rate.

Defense Science and Technology Success Stories

DTIC Science & Technology

2007-01-01

Active Auroral Research Project ( HAARP ) ........................................................................136 Weapons Strategic Illuminator Laser...drawing 136 Service/Agency Background: The High Frequency Active Auroral Research Project ( HAARP ) developed new experimental research capabilities and...Appropriation Act provided funds for the creation of HAARP , jointly managed by the Air Force Research Laboratory and the Office of Naval Research to exploit

Investigation of ionospheric disturbances and associated diagnostic techniques. Final report, 1 January 1992-31 December 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, L.M.

1995-12-12

The objectives of this research and development program were to conduct simulation modeling of the generation and propagation of atmospheric acoustic signals associated with surface and subsurface ground disturbances; to construct an experimental measurement system for exploratory research studies of acoustic generated ionospheric disturbances; to model high power radio wave propagation through the ionosphere, including nonlinear wave plasma interaction effects; and to assist in the assessment of diagnostic systems for observation of ionospheric modification experiments using existing and planned high latitude high power RF transmitting facilities. A computer simulation of ionospheric response to ground launched acoustic pulses was constructed andmore » results compared to observational data associated with HF and incoherent scatter radar measurements of ionospheric effects produced by earthquakes and ground level explosions. These results were then utilized to help define the design, construct and test for an HF Doppler radar system. In addition, an assessment was conducted of ionospheric diagnostic instruments proposed for the Air Force/Navy High Frequency Active Auroral Research Program (HAARP).« less

SATSIN System Manual.

DTIC Science & Technology

1995-01-01

This report outlines the design, functions and operation of the HAARP Diagnostic Satellite Scintillation (SATSIN) system that will be used to...be located so that the propagation path from satellite radio beacons passes through the heated volume created by HAARP . The signal, altered in phase...characteristics of the scintillation. From this information, the strength, shape and motion of the in situ irregularities generated by HAARP can be implied. The

Ionospheric Sensor Developments for the Year-2000 Solar Maximum

DTIC Science & Technology

2000-10-23

locations, work during the year enhanced and exploited several diagnostic instruments deployed for the High frequency Active Aurora Research Program ( HAARP ...Under HAARP , measurements employing both GPS and coherent VHF-UHF signals transmitted from satellites in low-earth polar orbit resulted in time...histories and latitudinal scans of absolute TEC over Maska, and enhanced operation of the HAARP classic riometer resulted in essentially continuous

Ionospheric data assimilation applied to HF geolocation in the presence of traveling ionospheric disturbances

NASA Astrophysics Data System (ADS)

Mitchell, C. N.; Rankov, N. R.; Bust, G. S.; Miller, E.; Gaussiran, T.; Calfas, R.; Doyle, J. D.; Teig, L. J.; Werth, J. L.; Dekine, I.

2017-07-01

Ionospheric data assimilation is a technique to evaluate the 3-D time varying distribution of electron density using a combination of a physics-based model and observations. A new ionospheric data assimilation method is introduced that has the capability to resolve traveling ionospheric disturbances (TIDs). TIDs are important because they cause strong delay and refraction to radio signals that are detrimental to the accuracy of high-frequency (HF) geolocation systems. The capability to accurately specify the ionosphere through data assimilation can correct systems for the error caused by the unknown ionospheric refraction. The new data assimilation method introduced here uses ionospheric models in combination with observations of HF signals from known transmitters. The assimilation methodology was tested by the ability to predict the incoming angles of HF signals from transmitters at a set of nonassimilated test locations. The technique is demonstrated and validated using observations collected during 2 days of a dedicated campaign of ionospheric measurements at White Sands Missile Range in New Mexico in January 2014. This is the first time that full HF ionospheric data assimilation using an ensemble run of a physics-based model of ionospheric TIDs has been demonstrated. The results show a significant improvement over HF angle-of-arrival prediction using an empirical model and also over the classic method of single-site location using an ionosonde close to the midpoint of the path. The assimilative approach is extendable to include other types of ionospheric measurements.

The Energy Spectrum of Accelerated Electrons from Wave-Plasma Interactions in the Ionosphere

DTIC Science & Technology

2012-06-29

STATEMENT Distribution A: Approved for public release; distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT A HAARP ...data was obtained. It was therefore necessary to find the resources to repeat the campaign effort (see budget below). A HAARP campaign was...were highly structured in space and time. This fact, and the lack of electron temperature data at HAARP , made data analysis difficult. It became

Analysis of the backscatter spectrum in an ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Kim, H.

1973-01-01

Predictions of the backscatter spectrum are compared, including effects of ionospheric inhomogeneity with experimental observations of incoherent backscatter from an artificially heated region. Calculations show that the strongest backscatter echo received is not, in fact, from the reflection level, but from a region some distance below (about 0.5 km for an experiment carried out at Arecibo), where the pump wave from a HF transmitter approximately 100 kW) is below the threshold for parametric amplification. By taking the standing wave pattern of the pump into account, asymmetry is explained of the up-shifted and down-shifted plasma lines in the backscatter spectrum, and the several peaks typically observed in the region of the spectrum near the HF transmitter frequency.

Imaging and Forecasting of Ionospheric Structures and Their System Impacts

DTIC Science & Technology

2005-01-27

Radiation Belt Remediation (RBR) studies were done and many of them remain active. The results of two HAARP heating experiments with the digisonde at...LORERS, Plasmasphere, HAARP , Cal/Val, Drift Software, ARTIST 4.5 16. SECURITY CLASSIFICATION OF: 17. UMITATION OF 1. NUMBER 19a. NAME OF RESPONSIBLE...STATION OBSERVATIONS 1 1.3 VLF INDUCED ELECTRON PITCH ANGLE SCATTERING (IEPAS) 2 1.4 HAARP CAMPAIGN 2 1.5 DRIFT SOFTWARE DEVELOPMENT 2 1.6 DISS SUPPORT

The calibration of an HF radar used for ionospheric research

NASA Astrophysics Data System (ADS)

From, W. R.; Whitehead, J. D.

1984-02-01

The HF radar on Bribie Island, Australia, uses crossed-fan beams produced by crossed linear transmitter and receiver arrays of 10 elements each to simulate a pencil beam. The beam points vertically when all the array elements are in phase, and is steerable by up to 20 deg off vertical at the central one of the three operating frequencies. Phase and gain changes within the transmitters and receivers are compensated for by an automatic system of adjustment. The 10 transmitting antennas are, as nearly as possible, physically identical as are the 10 receiving antennas. Antenna calibration using high flying aircraft or satellites is not possible. A method is described for using the ionospheric reflections to measure the polar diagram and also to correct for errors in the direction of pointing.

Development of a Space Flight Prototype Doppler Asymmetric Spatial Heterodyne (DASH) Spectrometer for the Measurement of Upper Atmospheric Winds

DTIC Science & Technology

2011-10-31

required for space flight. Dr. John Hughes and Dr. Abas Sivjee of Embry-Riddle Aeronautical University in Daytona FL and all the staff at the HAARP ...Laboratory, was conducted at the High Frequency Active Auroral Research Program ( HAARP ) facility in Alaska. ARROW was shipped to Anchorage AK from...the Naval Research Laboratory in Washington DC and was delivered, installed, and run at the HAARP facility by ARTEP Inc. personnel. The field

Final Technical Report for ELF/VLF Electromagnetic Detection and Characterization of Deeply Buried Targets

DTIC Science & Technology

1998-06-22

remote (e.g. HAARP /HIPAS), and natural sources (e.g. external noise); b) model the perturbed fields due to the specified underground structures...examined in this study are of three types • Remote man-made sources, e.g. HAARP /HIPAS • Local sources, e.g. metal-detector loop • Natural sources, e.g...The High Power Auroral Stimulation Observatory (HIPAS) and the High Frequency Active Auroral Research Program ( HAARP ) are capable of exciting plasma

Dynamic properties of ionospheric plasma turbulence driven by high-power high-frequency radiowaves

NASA Astrophysics Data System (ADS)

Grach, S. M.; Sergeev, E. N.; Mishin, E. V.; Shindin, A. V.

2016-11-01

A review is given of the current state-of-the-art of experimental studies and the theoretical understanding of nonlinear phenomena that occur in the ionospheric F-layer irradiated by high-power high-frequency ground-based transmitters. The main focus is on the dynamic features of high-frequency turbulence (plasma waves) and low-frequency turbulence (density irregularities of various scales) that have been studied in experiments at the Sura and HAARP heating facilities operated in temporal and frequency regimes specially designed with consideration of the characteristic properties of nonlinear processes in the perturbed ionosphere using modern radio receivers and optical instruments. Experimental results are compared with theoretical turbulence models for a magnetized collisional plasma in a high-frequency electromagnetic field, allowing the identification of the processes responsible for the observed features of artificial ionospheric turbulence.

Artificial plasma cusp generated by upper hybrid instabilities in HF heating experiments at HAARP

NASA Astrophysics Data System (ADS)

Kuo, Spencer; Snyder, Arnold

2013-05-01

High Frequency Active Auroral Research Program digisonde was operated in a fast mode to record ionospheric modifications by the HF heating wave. With the O mode heater of 3.2 MHz turned on for 2 min, significant virtual height spread was observed in the heater off ionograms, acquired beginning the moment the heater turned off. Moreover, there is a noticeable bump in the virtual height spread of the ionogram trace that appears next to the plasma frequency (~ 2.88 MHz) of the upper hybrid resonance layer of the HF heating wave. The enhanced spread and the bump disappear in the subsequent heater off ionograms recorded 1 min later. The height distribution of the ionosphere in the spread situation indicates that both electron density and temperature increases exceed 10% over a large altitude region (> 30 km) from below to above the upper hybrid resonance layer. This "mini cusp" (bump) is similar to the cusp occurring in daytime ionograms at the F1-F2 layer transition, indicating that there is a small ledge in the density profile reminiscent of F1-F2 layer transitions. Two parametric processes exciting upper hybrid waves as the sidebands by the HF heating waves are studied. Field-aligned purely growing mode and lower hybrid wave are the respective decay modes. The excited upper hybrid and lower hybrid waves introduce the anomalous electron heating which results in the ionization enhancement and localized density ledge. The large-scale density irregularities formed in the heat flow, together with the density irregularities formed through the parametric instability, give rise to the enhanced virtual height spread. The results of upper hybrid instability analysis are also applied to explain the descending feature in the development of the artificial ionization layers observed in electron cyclotron harmonic resonance heating experiments.

Artificial periodic irregularities in the high-latitude ionosphere excited by the HAARP facility

NASA Astrophysics Data System (ADS)

Bakhmetieva, N. V.; Grach, S. M.; Sergeev, E. N.; Shindin, A. V.; Milikh, G. M.; Siefring, C. L.; Bernhardt, P. A.; McCarrick, M.

2016-07-01

We present results of the new observations of artificial periodic irregularities (APIs) in the ionosphere using the High Frequency Active Auroral Research Program (HAARP) heating facility carried out in late May and early June 2014.The objective of this work is to detect API using high-latitude facility and analyze possible differences of the temporal and spatial variations of the API echoes in the high (HAARP) and middle (Sura) latitudes. Irregularities were created by the powerful wave of X mode and were sounded using the short probing pulses signals of X mode. API echoes were observed in the D, E, and F regions of the ionosphere. Amplitudes and characteristic times of the API echoes were measured. The API growth and decay times at HAARP (high latitudes) observed were similar to those at the Sura heating facility (midlatitudes).

Low frequency electric field variations during HF transmissions on a mother-daughter rocket

NASA Technical Reports Server (NTRS)

Rosenberg, T. J.; Maynard, M. C.; Holtet, J. A.; Karlsen, N. O.; Egeland, A.; Moe, T. E.; Troim, J.

1977-01-01

HF wave propagation experiments were conducted on Mother-Daughter rockets in the polar ionosphere. Swept frequency transmissions from the Mother, nominally covering the range from 0.5 to 5 MHz in both CW and pulse modes, are received by the Daughter. In the most recent rocket of the series, the Mother also contained an AC electric field spectrometer covering the frequency range from 10 Hz to 100 kHz in four decade bands. The low frequency response of the ionosphere with respect to waves emitted from the onboard HF transmitter is examined.

The Precision Expandable Radar Calibration Sphere (PERCS) With Applications for Laser Imaging and Ranging

NASA Astrophysics Data System (ADS)

Bernhardt, P.; Nicholas, A.; Thomas, L.; Davis, M.; Hoberman, C.; Davis, M.

The Naval Research Laboratory will provide an orbiting calibration sphere to be used with ground-based laser imaging telescopes and HF radio systems. The Precision Expandable Radar Calibration Sphere (PERCS) is a practical, reliable, high-performance HF calibration sphere and laser imaging target to orbit at about 600 km altitude. The sphere will be made of a spherical wire frame with aspect independent radar cross section in the 3 to 35 MHz frequency range. The necessary launch vehicle to place the PERCS in orbit will be provided by the Department of Defense Space Test Program. The expandable calibration target has a stowed diameter of 1 meter and a fully deployed diameter of 10.2 meters. A separate deployment mechanism is provided for the sphere. After deployment, the Precision Expandable Radar Calibration Sphere (PERCS) with 180 vertices will be in a high inclination orbit to scatter radio pulses from a number of ground systems, including (1) over-the-horizon (OTH) radars operated by the United States and Australia; (2) high power HF facilities such as HAARP in Alaska, EISCAT in Norway, and Arecibo in Puerto Rico; (3) the chain of high latitude SuperDARN radars used for auroral region mapping; and (4) HF direction finding for Navy ships. With the PERCS satellite, the accuracy of HF radars can be periodically checked for range, elevation, and azimuth errors. In addition, each of the 360 vertices on the PERCS sphere will support an optical retro-reflector for operations with ground laser facilities used to track satellites. The ground laser systems will be used to measure the precise location of the sphere within one cm accuracy and will provide the spatial orientation of the sphere as well as the rotation rate. The Department of Defense facilities that can use the corner-cube reflectors on the PERCS include (1) the Air Force Maui Optical Site (AMOS), (2) the Starfire Optical Range (SOR), and (3) the NRL Optical Test Facility (OTF).

Technology Transition and Adoption: A Study in Search of Metrics for Evaluating Transition

DTIC Science & Technology

2010-12-01

Coalitions and Agents Project (Fast C2AP) 3 Direct Thermal to Electric Conversion (DTEC) 3 High-Frequency Active Auroral Project ( HAARP ) Instrument...which the technology is disruptive: 40 RAID TEAM SDS M&DC2 LCCMD DTEC AT3 WASP DOTS LASER Boomerang Virtual Autopsy  Program HAARP PCES Ultralog Sticky...RAID SDS Fast C2AP DTEC AT3 WASP Radar Scope DOTS SPEYES LASER Boomerang MAV ACTD HAARP TEAM PCES Ultralog Sticky Flare Active Templates LCCMD VIVID

Multisite Optical Imaging of Artificial Ionospheric Plasmas (Postprint)

DTIC Science & Technology

2011-11-09

Frequency Active Auroral Research Program ( HAARP ) facility in Gakona, Alaska (62.4◦ N 145◦ W) after the trans- mitter reached full 3.6-MW power, these...The experiment was carried out on November 19, 2009, between 02:26 UT and 02:43:50 UT. Optical images were acquired at the HAARP site at 557.7 nm (O 1S...noise and integrated for 5 s at a temperature of −40 ◦C. A second system located 160 km north of the HAARP near Delta Junction used an Apogee Alta

Detection and Characterization of Traveling Ionospheric Disturbances (TIDs) with GPS and HF sensors

NASA Astrophysics Data System (ADS)

Groves, K. M.; Paznukhov, V.; Bullett, T. W.; Mackenzie, E.

2014-12-01

Recently there has been increasing interest and awareness in the coupling between the neutral atmosphere and the ionosphere and specifically in processes that cause wave-like non-stationary perturbations in the bottom-side of the F-region. A class of these perturbations having periods greater than about five minutes and wavelengths greater than a kilometer or so are believed to occur routinely and propagate throughout the ionosphere; they are known as traveling ionospheric disturbances (TIDs). In this study we investigate ground-based techniques for detecting and characterizing TIDs with periods ranging from 30-90 minutes and wavelengths of 10s of km or more. These waves are believed to affect the Doppler and propagation angles of high frequency (HF) radio waves refracting through the affected regions. Wave-like perturbations are also commonly observed in GPS total electron content (TEC) data. In the current study we monitor a number of different commercial HF broadcast transmitters from a station in Wallops Island, VA and collect GPS TEC data from numerous stations along the path between the HF receiver at Wallops and specific HF transmitters. The objective is to understand the relationship between TID signatures on HF and GPS sensors and to possibly characterize TIDs using such observations, including propagation velocity, amplitude, wavelength and potentially source. Given that GPS TEC data are now relatively abundant around the globe, establishing a reliable technique for quantifying TIDs with these measurements would yield an important new technique towards developing a global TID monitoring capability that could support ionosphere-thermosphere coupling science as well as potential monitoring capabilities for natural disasters (e.g., earthquakes, tsunamis, volcanic eruptions) with significant TID signatures.

What Can We Learn About the Ionosphere Using the EISCAT Heating Facility?

DTIC Science & Technology

2006-06-01

1970s to do both plasma physics and geophysical research. At present there are five operating facilities: HIPAS [1] and HAARP [2] in Alaska, Heating...1995: HAARP (Alaska) •2003: SPEAR (Svalbard) World overview 32 (8) 22 (16) 0.19 4-6 (2-3) 78.9 N 78.15 W SPEAR Spitsbergen Norway 150-280180-340...19.2 E 62.39 N 145.15W 65.0 N 147.0 W 18.3 N 66.8 W 40.18 N 104.73 E Geographic Coordinates SURA Russia Tromsø Norway HAARP Alaska USA HIPAS Alaska

Studies of Ionospheric Processes in the Atmosphere and the Laboratory

DTIC Science & Technology

2006-06-01

relevance to HAARP observations, and on vibrationally-excited levels of the O2 ground state [2] and the b1Σ +g excited state [3]. Synergy with the...UT [20] 29.4 (33) 260 0.94 .077 3/24/95 1737 UT 43.4 (44) 278 0.54 0.53 HAARP 62N, 145W 3/20/04 0617 UT [21] 54 (44) 290 0.33 0.54... HAARP 0.62 5.0E8 1.09E8 4.6 Studies of Ionospheric Processes in the Atmosphere and the Laboratory RTO-MP-IST-056 1 - 9 UNCLASSIFIED/UNLIMITED

Time-Reversal Based Range Extension Technique for Ultra-Wideband (UWB) Sensors and Applications in Tactical Communications and Networking

DTIC Science & Technology

2009-07-16

Frequency (MHz) Figure 3.4: CABLE SMA/SMA 24" RG-316DS. CABLE SMA PLUG-PLUG HF -.086 8" 3.1. TRANSMITTER IMPLEMENTATION 13 Length: 8.0" (203.2mm) Color...Gray RG Type: Hand Formable .086 Connector: Type SMA Male to SMA Male Features: Shielded "• JI Figure 3.5: CABLE SMA PLUG-PLUG HF -.086 8...34 . • CABLE SMA PLUG-PLUG HF -.141 8" Length: 8.0" (203.2mm) Color: Gray RG Type: Hand Formable .141 14 CHAPTER 3. 2 BY I MISO SYSTEM DEVELOPMENT

Attenuation of Scintillation of Discrete Cosmic Sources during Nonresonant HF Heating of the Upper Ionosphere

NASA Astrophysics Data System (ADS)

Bezrodny, V. G.; Watkins, B.; Charkina, O. V.; Yampolski, Y. M.

2014-03-01

The aim of the work is to experimentally investigate the response of scintillation spectra and indices of discrete cosmic sources (DCS) to modification of the ionospheric F-region by powerful electromagnetic fields with frequencies exceeding the Langmuir and upper hybrid ones. The results of a special experiment on the scintillations of radiation from DCS Cygnus A observed with using the 64-beam imaging riometer located near the Gakona village (Alaska, USA) are here presented. The ionosphere was artificially disturbed by powerful HAARP heater. Under the studied conditions of nonresonant heating of the ionospheric plasma, an earlier unknown effect of reducing the level of DCS scintillation was discovered. The theoretical interpretation has been given for the discovered effect, which using allowed the proposed technique of solving the inverse problem (recovery deviations of average electron density and temperature in the modified region from their unperturbed values).

Influence of heating experiments on parameters of Schumann resonances

NASA Astrophysics Data System (ADS)

Agranat, Irina; Sivokon, Vladimir

2017-10-01

Recently the significant increase in intensity of researches in the field of the fissile impact on geophysical processes in various environments is noted. Special attention is paid to a research of impact on an ionosphere of a potent short-wave radio emission of heating stands. Today experiments on change of an ionosphere are made generally at stands HAARP, EISCAT in Tromse (Norway). Within the Russian campaign (Tomsk) EISCAT/heating (AARI_HFOX) made from October 19 to October 30, 2016 experiments on impact on an ionosphere F-layer by the radiation potent HF. For assessment of impact of these experiments on geophysical processes mathematical methods carried out the analysis of change of the parameters of the Schumann resonances received on the basis of data from the station of constant observation of the Schumann resonances in the city of Tomsk, the Tomsk State University (Russia).

Multi Station Frequency Response and Polarization of ELF/VLF Signals Generated via Ionospheric Modification

NASA Astrophysics Data System (ADS)

Maxworth, Ashanthi; Golkowski, Mark; University of Colorado Denver Team

2013-10-01

ELF/VLF wave generation via HF modulated ionospheric heating has been practiced for many years as a unique way to generate waves in the ELF/VLF band (3 Hz - 30 kHz). This paper presents experimental results and associated theoretical modeling from work performed at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska, USA. An experiment was designed to investigate the modulation frequency dependence of the generated ELF/VLF signal amplitudes and polarization at multiple sites at distances of 37 km, 50 km and 99 km from the facility. While no difference is observed for X mode versus O mode modulation of the heating wave, it is found that ELF/VLF amplitude and polarization as a function of modulated ELF/VLF frequency is different for each site. An ionospheric heating code is used to determine the primary current sources leading to the observations.

Solar Radar Experiments

DTIC Science & Technology

1998-01-01

communications satellites and electric power grids. RELATED PROJECTS Studies with the HAARP radar facility being constructed in Alaska are conducted with...on wave-plasma interactions and also are assessing the possible use of HAARP as a solar radar. REFERENCES James, J. C., Radar studies of the sun, in

Impact of active geomagnetic conditions on stimulated radiation during ionospheric second electron gyroharmonic heating

NASA Astrophysics Data System (ADS)

Bordikar, M. R.; Scales, W. A.; Mahmoudian, A.; Kim, H.; Bernhardt, P. A.; Redmon, R.; Samimi, A. R.; Brizcinski, S.; McCarrick, M. J.

2014-01-01

Recently, narrowband emissions ordered near the H+ (proton) gyrofrequency (fcH) were reported in the stimulated electromagnetic emission (SEE) spectrum during active geomagnetic conditions. This work presents new observations and theoretical analysis of these recently discovered emissions. These emission lines are observed in the stimulated electromagnetic emission (SEE) spectrum when the transmitter is tuned near the second electron gyroharmonic frequency (2fce) during recent ionospheric modification experiments at the High Frequency Active Auroral Research (HAARP) facility near Gakona, Alaska. The spectral lines are typically shifted below and above the pump wave frequency by harmonics of a frequency roughly 10% less than fcH (≈ 800 Hz) with a narrow emission bandwidth less than the O+ gyrofrequency (≈ 50 Hz). However, new observations and analysis of emission lines ordered by a frequency approximately 10% greater than fcH are presented here for the first time as well. The interaction altitude for the heating for all the observations is in the range of 160 km up to 200 km. As described previously, proton precipitation due to active geomagnetic conditions is considered as the reason for the presence of H+ ions known to be a minor background constituent in this altitude region. DMSP satellite observations over HAARP during the heating experiments and ground-based magnetometer and riometer data validate active geomagnetic conditions. The theory of parametric decay instability in multi-ion component plasma including H+ ions as a minority species described in previous work is expanded in light of simultaneously observed preexisting SEE features to interpret the newly reported observations. Impact of active geomagnetic conditions on the SEE spectrum as a diagnostic tool for proton precipitation event characterization is discussed.

Multiple-Station Observation of Frequency Dependence and Polarization Characteristics of ELF/VLF waves generated via Ionospheric Modification

NASA Astrophysics Data System (ADS)

Maxworth, A. S.; Golkowski, M.; Cohen, M.; Moore, R. C.

2014-12-01

Generation of Extremely Low Frequency (ELF) and Very Low Frequency (VLF) signals through ionospheric modification has been practiced for many years. Heating the lower ionosphere with high power HF waves allows for modulation of natural current systems. Our experiments were carried out at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska, USA. In this experiment, the ionosphere was heated with a vertical amplitude modulating signal and the modulation frequency was changed sequentially within an array of 40 frequencies followed by a frequency ramp. The observed magnetic field amplitude and polarization of the generated ELF/VLF signals were analyzed for multiple sites and as a function of modulation frequency. Our three observation sites: Chistochina, Paxson and Paradise are located within 36km (azimuth 47.7°), 50.2km (azimuth -20°) and 99km (azimuth 80.3°) respectively. We show that the peak amplitudes observed as a function of frequency result from vertical resonance in the Earth-ionosphere waveguide and can be used to diagnose the D-region profile. Polarization analysis showed that out of the three sites Paxson shows the highest circularity in the magnetic field polarization, compared to Chistochina and Paradise which show highly linear polarizations. The experimental results were compared with a theoretical simulation model results and it was clear that in both cases, the modulated Hall current dominates the observed signals at Chistochina and Paradise sites and at Paxson there is an equal contribution from Hall and Pedersen currents. The Chistochina site shows the highest magnetic field amplitudes in both experimental and simulation environments. Depending upon the experimental and simulation observations at the three sites, a radiation pattern for the HAARP ionospheric heater can be mapped

Modeling and design for a new ionospheric modification experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sales, G.S.; Platt, I.G.; Haines, D.M.

1990-10-01

Plans are now underway to carry out new HF oblique ionospheric modification experiments with increased radiated power using a new high gain antenna system and a 1 MW transmitter. The output of this large transmitting system will approach 90 dBW. An important part of this program is to determine the existence of a threshold for non-linear effects by varying the transmitter output. For these experiments we are introducing a new ET probe system, a low power oblique sounder, to be used along the same propagation path as the high power disturbing transmitter. This concept was first used by soviet researchersmore » to insure that this diagnostic signal always passes through the modified region of the ionosphere. The HF probe system will use a low power (150 W) CW signal shifted by approximately 40 kHz from the frequency used by the high power system. The transmitter for the probe system will be at the same location as the high power transmitter while the probe receiver will be 2400 km down range. The probe receiving system uses multiple antennas to measure the the vertical and azimuthal angle of arrival as well the Doppler frequency shift of the arriving probe signal. The three antenna array will be in an L configuration to measure the phase differences between the antennas. At the midpath point a vertical sounder will provide the ionospheric information necessary for the frequency management of the experiment. Real-time signal processing will permit the site operators to evaluate the performance of the system and make adjustments during the experiment. A special ray tracing computer will be used to provide real-time frequencies and elevation beam steering during the experiment. A description of the system and the analysis used in the design of the experiment are presented.« less

Ionospheric very low frequency transmitter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuo, Spencer P.

2015-02-15

The theme of this paper is to establish a reliable ionospheric very low frequency (VLF) transmitter, which is also broad band. Two approaches are studied that generate VLF waves in the ionosphere. The first, classic approach employs a ground-based HF heater to directly modulate the high latitude ionospheric, or auroral electrojet. In the classic approach, the intensity-modulated HF heater induces an alternating current in the electrojet, which serves as a virtual antenna to transmit VLF waves. The spatial and temporal variations of the electrojet impact the reliability of the classic approach. The second, beat-wave approach also employs a ground-based HFmore » heater; however, in this approach, the heater operates in a continuous wave mode at two HF frequencies separated by the desired VLF frequency. Theories for both approaches are formulated, calculations performed with numerical model simulations, and the calculations are compared to experimental results. Theory for the classic approach shows that an HF heater wave, intensity-modulated at VLF, modulates the electron temperature dependent electrical conductivity of the ionospheric electrojet, which, in turn, induces an ac electrojet current. Thus, the electrojet becomes a virtual VLF antenna. The numerical results show that the radiation intensity of the modulated electrojet decreases with an increase in VLF radiation frequency. Theory for the beat wave approach shows that the VLF radiation intensity depends upon the HF heater intensity rather than the electrojet strength, and yet this approach can also modulate the electrojet when present. HF heater experiments were conducted for both the intensity modulated and beat wave approaches. VLF radiations were generated and the experimental results confirm the numerical simulations. Theory and experimental results both show that in the absence of the electrojet, VLF radiation from the F-region is generated via the beat wave approach. Additionally, the beat wave approach generates VLF radiations over a larger frequency band than by the modulated electrojet.« less

Numerical simulation of the structure of the high-latitude ionospheric F region during meridional HF propagation

NASA Astrophysics Data System (ADS)

Andreev, M. Yu.; Mingaleva, G. I.; Mingalev, V. S.

2007-08-01

A previously developed model of the high-latitude ionosphere is used to calculate the distribution of the ionospheric parameters in the polar region. A specific method for specifying input parameters of the mathematical model, using the experimental data obtained by the method of satellite radio tomography, is used in this case. The spatial distributions of the ionospheric parameters characterized by a complex inhomogeneous structure in the high-latitude region, calculated with the help of the mathematical model, are used to simulate the HF propagation along the meridionally oriented radio paths extending from middle to high latitudes. The method for improving the HF communication between a midlatitude transmitter and a polar-cap receiver is proposed.

SuperDARN elevation angle calibration using HAARP-induced backscatter

NASA Astrophysics Data System (ADS)

Shepherd, S. G.; Thomas, E. G.; Palinski, T. J.; Bristow, W.

2017-12-01

SuperDARN radars rely on refraction in the ionosphere to make Doppler measurements of backscatter from ionospheric irregularities or the ground/sea, often to ranges of 4000 km or more. Elevation angle measurements of backscattered signals can be important for proper geolocation, mode identification and Doppler velocity corrections to the data. SuperDARN radars are equipped with a secondary array to make elevation angle measurements, however, calibration is often difficult. One method of calibration is presented here, whereby backscatter from HAARP-induced irregularities, at a known location, is used to independently determine the elevation angle of signals. Comparisons are made for several radars with HAARP in their field-of-view in addition to the results obtained fromray-tracing in a model ionosphere.

Stimulated Brillouin scatter and stimulated ion Bernstein scatter during electron gyroharmonic heating experiments

NASA Astrophysics Data System (ADS)

Fu, H.; Scales, W. A.; Bernhardt, P. A.; Samimi, A.; Mahmoudian, A.; Briczinski, S. J.; McCarrick, M. J.

2013-09-01

Results of secondary radiation, Stimulated Electromagnetic Emission (SEE), produced during ionospheric modification experiments using ground-based high-power radio waves are reported. These results obtained at the High Frequency Active Auroral Research Program (HAARP) facility specifically considered the generation of Magnetized Stimulated Brillouin Scatter (MSBS) and Stimulated Ion Bernstein Scatter (SIBS) lines in the SEE spectrum when the transmitter frequency is near harmonics of the electron gyrofrequency. The heater antenna beam angle effect was investigated on MSBS in detail and shows a new spectral line postulated to be generated near the upper hybrid resonance region due to ion acoustic wave interaction. Frequency sweeping experiments near the electron gyroharmonics show for the first time the transition from MSBS to SIBS lines as the heater pump frequency approaches the gyroharmonic. Significantly far from the gyroharmonic, MSBS lines dominate, while close to the gyroharmonic, SIBS lines strengthen while MSBS lines weaken. New possibilities for diagnostic information are discussed in light of these new observations.

Partnering with law enforcement to deliver good public health: the experience of the HIV/AIDS Asia regional program.

PubMed

Sharma, Mukta; Chatterjee, Anindya

2012-07-09

In the South-East Asia region, the drug control and supply reduction agenda is of high political importance. A multitude of law enforcement agencies are engaged in this work. Nationwide campaigns such as the "Strike- Hard" campaign in China or the "war on drugs" in Thailand dominate the landscape. Viet Nam's response to drug use has historically focused on deterrence through punishment and supply-side measures. This policy environment is further complicated by lack of evidence-based drug dependence treatment in several settings. The public health consequences of this approach have been extremely serious, with some of the highest documented prevalence of preventable blood-borne viral infections, including HIV, and hepatitis B and C. The wider socioeconomic consequences of this have been borne by families, communities and the governments themselves.The HIV/AIDS Asia Regional Program (HAARP) aims to stop the spread of HIV associated with drug use in South-East Asia and parts of southern China. HAARP works across five countries (Cambodia, China Burma, Laos, Viet Nam) chiefly through the Ministries of Health and Social Affairs, National Drug Control Agencies, and Public Security sectors, including prisons. HAARP has also engaged with UN agencies and a wide range of civil society organisations, including organisations of people who use drugs, to ensure their meaningful involvement in matters that directly affect them. We describe the experience of HAARP in implementing a large-scale harm reduction programme in the Sub-Mekong Region. HAARP chose to direct its efforts in three main areas: supporting an enabling environment for effective harm reduction policies, building core capacity among national health and law enforcement agencies, and supporting "universal access" goals by making effective, high-coverage services available to injecting drug users and their partners.The activities supported by HAARP are humble yet important steps. However, a much higher political-level dialogue is needed. The current huge gap of human rights standards in drug control practices also needs to be bridged immediately. Public health that embraces a rights-based approach must be given its fair share of policy space, budget and influence.

Partnering with law enforcement to deliver good public health: the experience of the HIV/AIDS Asia regional program

PubMed Central

2012-01-01

In the South-East Asia region, the drug control and supply reduction agenda is of high political importance. A multitude of law enforcement agencies are engaged in this work. Nationwide campaigns such as the “Strike- Hard” campaign in China or the “war on drugs” in Thailand dominate the landscape. Viet Nam’s response to drug use has historically focused on deterrence through punishment and supply-side measures. This policy environment is further complicated by lack of evidence-based drug dependence treatment in several settings. The public health consequences of this approach have been extremely serious, with some of the highest documented prevalence of preventable blood-borne viral infections, including HIV, and hepatitis B and C. The wider socioeconomic consequences of this have been borne by families, communities and the governments themselves. The HIV/AIDS Asia Regional Program (HAARP) aims to stop the spread of HIV associated with drug use in South-East Asia and parts of southern China. HAARP works across five countries (Cambodia, China Burma, Laos, Viet Nam) chiefly through the Ministries of Health and Social Affairs, National Drug Control Agencies, and Public Security sectors, including prisons. HAARP has also engaged with UN agencies and a wide range of civil society organisations, including organisations of people who use drugs, to ensure their meaningful involvement in matters that directly affect them. We describe the experience of HAARP in implementing a large-scale harm reduction programme in the Sub-Mekong Region. HAARP chose to direct its efforts in three main areas: supporting an enabling environment for effective harm reduction policies, building core capacity among national health and law enforcement agencies, and supporting “universal access” goals by making effective, high-coverage services available to injecting drug users and their partners. The activities supported by HAARP are humble yet important steps. However, a much higher political-level dialogue is needed. The current huge gap of human rights standards in drug control practices also needs to be bridged immediately. Public health that embraces a rights-based approach must be given its fair share of policy space, budget and influence. PMID:22769065

Contrasting O/X-mode Heater Effects on O-Mode Sounding echo and the Generation of Magnetic Pulsations

DTIC Science & Technology

2010-01-06

Micropulsation [10] The induced magnetic field variation was monitored by the fluxgate magnetometer located at Gakona, AK. The 1 sec resolution data...minutes on and 1 minute off, were explored. The experiments were monitored using the digisonde and magnetometer located at the HAARP facility. The...were explored. The experiments were monitored using the digisonde and magnetometer located at the HAARP facility. The results show that the

Transmission and reflection studies of thin films in the vacuum ultraviolet

NASA Technical Reports Server (NTRS)

Peterson, Lennart R.

1989-01-01

Both the transmittance and reflectance of 2 mm thick MgF2 substrates and of thin films of BaF2, CaF2, LaF3, MgF2, Al2O3, HfO2, and SiO2 deposited on these substrates were measured for the wavelength range 120 nm to 230 nm. Results for BaF2, LaF2 and MgF2 show promise as being good materials from which interference filters can be made. The software and related hardware needed to take large amounts of data automatically in future measurements of the transmittance and reflectance was developed.

{A Review of Working Group 2 (Advanced Terrestrial Systems) of the COST 296 Action}

NASA Astrophysics Data System (ADS)

Warrington, E. M.; Tulunay, E.

2009-04-01

E.M. Warrington, E. Tulunay, N.M. Abbasi, J. Azevedo, L. Bertel, A. Bourdillon, E. Benito, C. Bianchi, A. Casimiro, L. Economou, Y. Erhel, S.M. Feeney, S.D. Gunashekar, H. Haralambous, D. Lemur, F. Marie, J.P. Monilie, M. Muriuki, M. Oger M. Pietrella, V. Rannou, H. Rothkaehl, S. Saillant, S. Salous, O. Sari, A.J. Stocker, H.J. Strangeways, Y. Tulunay and N.Y. Zaalov This paper deals with the research undertaken during the COST 296 Action in Working Group 2 on Advanced Terrestrial Systems. The Working Group comprised three work packages covering various topics: Radar and Radiolocation, HF/MF Communications, and Spectrum Management. Results from this Working Group are presented in this paper, and may be summarised as follows. Aspects of HF propagation The propagation characteristics of radio signals are important parameters to consider when designing and operating radio systems. From the point of view Working Group 2 of the COST-296 Action, interest lies with effects associated with propagation via the ionosphere of signals within the HF band. Several aspects were covered: The directions of arrival and times of flight of signals received over a path oriented along the trough have been examined and several types of propagation effects identified. Of particular note, combining the HF observations with satellite measurements has identified the presence of irregularities within the floor of the trough that result in propagation displaced from the great circle direction. An understanding of the propagation effects that result in deviations of the signal path from the great circle direction are of particular relevance to the operation of HF radiolocation systems. Inclusion of the results from the above mentioned measurements into a propagation model of the northerly ionosphere (i.e. those regions of the ionosphere located poleward of, and including, the mid-latitude trough) and the use of this model to predict the coverage expected from transmitters where the signals impinge on the northerly ionosphere. Development of inversion techniques enabling backscatter ionograms obtained by an HF radar to be used to estimate the ionospheric electron density profile. This development facilitates the operation of over the horizon HF radars by enhancing the frequency management aspects of the systems. Various propagation prediction techniques have been tested against measurements made over the trough path mentioned above, and also over a long-range path between Cyprus and the UK. The effect of changes in the levels of ionospheric disturbances on the operational availability at various data throughput rates has been examined for the trough path mentioned earlier. Utilization of antenna arrays in HF systems Various radio systems are based on arrays of antennas and associated signal processing techniques. Classically, radio direction finding operates with a multi-channel receiving system connected to an array of receiving antennas. More recently, MIMO architectures have been proposed to increase the capacity of radio links by the use of antenna arrays at both the transmitter and receiver ends of the link. Several aspects were covered within COST-296: Experimental work carried out to characterise the HF channel from the point of view of HF-MIMO systems. Considering various array geometries and a diversity of the transmitting antennas, the correlation coefficients of the different transmitter-receiver paths were estimated to investigate the effectiveness of a MIMO structure for HF radio links. The dependence of the inter element correlation relatively to the sensors spacing within MIMO systems. Simulations were carried out with a model of the HF channel. Sensitivity analysis of different structures of antenna array for direction finding applications. Better robustness of heterogeneous arrays to model errors by comparison to classical homogeneous structures was demonstrated. Computation of antenna array weighting factors to reduce the sidelobe levels and to create nulls in the direction of interfering signals. HF Spectrum Management A long-term joint UK-Swedish-German project has previously been undertaken on the measurement and analysis of HF spectral occupancy over northern Europe. The results from that research were shared at COST 296 with research focussed in four areas: Procedures for measuring and modelling spectral occupancy, with final stable-day and stable-nighttime models for northern Europe, when using calibrated monopole antennas. Preliminary investigation into the possible application of artificial neural networks to predict spectral occupancy in the HF spectrum. In particular, a study of the development of a single ITU allocation model for the diurnal variation of HF spectral occupancy over Linköping, Sweden was undertaken. Application of Neural Networks as a means of optimising the reliability of HF groundwave communication systems by predicting the detrimental effect of interference from other users. Application of Neural Networks as a means of optimising the reliability of HF communication systems by predicting the detrimental effect of interference from other users and its variability due to the ionosphere. In particular, the development of a long-term interference prediction model for the HF spectrum was developed.

An Experimental Investigation of the Performance of a New Wideband, Directional Receiver/Transmitter Sonar System

DTIC Science & Technology

2009-08-01

caractéristiques directionnelles dépendent beaucoup de la fréquence. Les mesures des courbes de réponse en tension d’émission du projecteur et des diagrammes ...Development Knowledge and Information Management FFT Fast fourier transform HF MMPP High frequency multi-mode pipe projector kHz kilohertz MMPP

Network of Internet-Controlled HF Receivers for Ionospheric Researches

NASA Astrophysics Data System (ADS)

Koloskov, A. V.; Yampolski, Y. M.; Zalizovski, A. V.; Galushko, V. G.; Kascheev, A. S.; La Hoz, C.; Brekke, A.; Beley, V. S.; Rietveld, M. T.

2014-12-01

A network of HF receivers intended for multi-position monitoring of the ionosphere is described. At present, it includes nine observation sites located at high, middle and low latitudes in both hemispheres of the Earth. The basic element of the network is a small- size receiving and measuring units designed at the Institute of Radio Astronomy (IRA) of the National Academy of Sciences of Ukraine (NASU) on the basis of a personal computer equipped with commercial digital receiving modules. Software packages developed by the authors make it possible to remotely control the facilities via the Internet network. The received emissions are HF signals from special transmitters and broadcast radio stations. These are processed using Doppler and pulse selection algorithms. In the Internet-controlled mode, the observation results are transferred to the main server in real time to be automatically processed and visualized at the website of the IRA NASU’s Department of Radiophysics of Geospace. Several examples of using the observation results obtained with the HF receiver network for diagnostics of dynamic processes in the near-Earth plasma are presented. The advantages of the multiposition mode of observations are discussed. The possibility of upgrading the HF facilities to provide measuring angles of arrival of signals is considered.

Band gap and mobility of epitaxial perovskite BaSn1 -xHfxO3 thin films

NASA Astrophysics Data System (ADS)

Shin, Juyeon; Lim, Jinyoung; Ha, Taewoo; Kim, Young Mo; Park, Chulkwon; Yu, Jaejun; Kim, Jae Hoon; Char, Kookrin

2018-02-01

A wide band-gap perovskite oxide BaSn O3 is attracting much attention due to its high electron mobility and oxygen stability. On the other hand, BaHf O3 was recently reported to be an effective high-k gate oxide. Here, we investigate the band gap and mobility of solid solutions of BaS n1 -xH fxO3 (x =0 -1 ) (BSHO) as a basis to build advanced perovskite oxide heterostructures. All the films were epitaxially grown on MgO substrates using pulsed laser deposition. Density functional theory calculations confirmed that Hf substitution does not create midgap states while increasing the band gap. From x-ray diffraction and optical transmittance measurements, the lattice constants and the band-gap values are significantly modified by Hf substitution. We also measured the transport properties of n -type La-doped BSHO films [(Ba ,La ) (Sn ,Hf ) O3 ] , investigating the feasibility of modulation doping in the BaSn O3/BSHO heterostructures. The Hall measurement data revealed that, as the Hf content increases, the activation rate of the La dopant decreases and the scattering rate of the electrons sharply increases. These properties of BSHO films may be useful for applications in various heterostructures based on the BaSn O3 system.

Electromagnetic interference impact of the proposed emitters for the High Frequency Active Auroral Research Program (HAARP). Interim report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertshaw, G.A.; Snyder, A.L.; Weiner, M.M.

1993-05-14

The proposed HAARP emitters at the Gakona (Alaska) preferred site and at the Clear AFS (Alaska) alternative site are the Ionospheric Research Instrument (IRI), the Incoherent Scatter Radar (ISR), and the Vertical Incidence Sounder(VIS). The electromagnetic interference (EMI) impact of those emitters on receiving systems in the vicinity of the sites is estimated in this study. The results are intended for use as an input to the Air Force Environmental Impact Statement as part of the Environmental Impact Analysis Process.

47 CFR 73.757 - System specifications for single-sideband (SSB) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2013 CFR

2013-10-01

... emission is one giving the same audio-frequency signal-to-noise ratio at the receiver output as the... is equally valid for both DSB and SSB emissions. (3) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz with a further slope of...

47 CFR 73.756 - System specifications for double-sideband (DBS) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... Nominal carrier frequencies shall be integral multiples of 5 kHz. (2) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz and the lower... processing. If audio-frequency signal processing is used, the dynamic range of the modulating signal shall be...

47 CFR 73.756 - System specifications for double-sideband (DBS) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2012 CFR

2012-10-01

.... Nominal carrier frequencies shall be integral multiples of 5 kHz. (2) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz and the lower... processing. If audio-frequency signal processing is used, the dynamic range of the modulating signal shall be...

47 CFR 73.757 - System specifications for single-sideband (SSB) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2014 CFR

2014-10-01

... emission is one giving the same audio-frequency signal-to-noise ratio at the receiver output as the... is equally valid for both DSB and SSB emissions. (3) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz with a further slope of...

47 CFR 73.756 - System specifications for double-sideband (DBS) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... Nominal carrier frequencies shall be integral multiples of 5 kHz. (2) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz and the lower... processing. If audio-frequency signal processing is used, the dynamic range of the modulating signal shall be...

47 CFR 73.757 - System specifications for single-sideband (SSB) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2012 CFR

2012-10-01

... emission is one giving the same audio-frequency signal-to-noise ratio at the receiver output as the... is equally valid for both DSB and SSB emissions. (3) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz with a further slope of...

47 CFR 73.756 - System specifications for double-sideband (DBS) modulated emissions in the HF broadcasting service.

Code of Federal Regulations, 2013 CFR

2013-10-01

.... Nominal carrier frequencies shall be integral multiples of 5 kHz. (2) Audio-frequency band. The upper limit of the audio-frequency band (at—3 dB) of the transmitter shall not exceed 4.5 kHz and the lower... processing. If audio-frequency signal processing is used, the dynamic range of the modulating signal shall be...

The role of Upper Hybrid Turbulence on HF Artificial Ionization

NASA Astrophysics Data System (ADS)

Papadopoulos, Konstantinos Dennis; Najmi, Amir; Eliasson, Bengt; Milikh, Gennady

2016-07-01

One of the most fascinating and scientifically interesting phenomena of active space experiments is the discovery of artificial ionization by Todd Pedersen when the HAARP ERP reached the GW level. The phenomenon has been well documented experimentally. A theoretical model based on ionization by energetic electrons accelerated by 50-100 V/m localized electric fields due to Strong Langmuir Turbulence (SLT) near the reflection surface of the HF pump wave, reproduced the observed dynamics of the descending plasma layer quite accurately. A major defect of the model was that the electron temperature in the SLT region was a free parameter. When taken as the 2000 K representing the ambient electron temperature the SLT driven electron flux was insufficient to produce ionization. An equivalent electron temperature of 5000 K or higher was necessary to reproduce the observations. The needed electron heating was attributed to the interaction of the HF at the Upper Hybrid (UH) resonant layer, approximately 5 Km below the reflection region where the HF electric field is perpendicular to the ambient magnetic field. The heated electrons expanded upwards along the magnetic field line and interacted with SLT fields near the resonance region. A consequence of this defect was that the theory could not explain the puzzling double resonance effect. Namely the observation that the ionization level was much stronger when the HF frequency and the UH resonance were a multiple of the electron cyclotron frequency. To remedy this we used a series of Vlasov simulations to explore the HF-plasma interaction in the vicinity of the UH resonance. The simulations followed the evolution of the spectral density of the electric field over a 7.5 MHz frequency band and cm scale lengths and of the electron distribution function over one millisecond for both double resonant and non-resonant cases. Many new features were revealed by the analysis of the simulations such as: 1. Broadening of the wave-number spectral region at the at the UH frequency 2. Excitation of all Bernstein modes associated with cyclotron frequency harmonics both below and above the UH frequency for both the resonant and non0resonant cases. 3. Moderate electron heating, in the form of bulk heating caused by first Bernstein mode, although its wave intensity is more than 20 dB lower than the intensity of the UH branch for all non-resonant cases. 4. Strong generation of non-thermal tails for the resonant cases, by the UH waves downshifted by the lower hybrid frequency when the downshifted frequency was equal to an harmonic of the electron gyro-frequency. The new UH turbulence resolves several f the mysteries associated with artificial ionization and suggests several new observations. Acknowledgment:Work supported by AFOSR MURI grant FA95501410019.

Unique concurrent observations of whistler mode hiss, chorus, and triggered emissions

NASA Astrophysics Data System (ADS)

Hosseini, Poorya; Gołkowski, Mark; Turner, Drew L.

2017-06-01

We present a unique 2 h ground-based observation of concurrent magnetospheric hiss, chorus, VLF triggered emissions as well as ELF/VLF signals generated locally by the High Frequency Active Auroral Research Program (HAARP) facility. Eccentricity of observed wave polarization is used as a criteria to identify magnetospheric emissions and estimate their ionospheric exit points. The observations of hiss and chorus in the unique background of coherent HAARP ELF/VLF waves and triggered emissions allow for more accurate characterization of hiss and chorus properties than in typical ground-based observations. Eccentricity and azimuth results suggest a moving ionospheric exit point associated with a single ducted path at L 5. The emissions exhibit dynamics in time suggesting an evolution of a magnetospheric source from hiss generation to chorus generation or a moving plasmapause location. We introduce a frequency band-limited autocorrelation method to quantify the relative coherency of the emissions. A range of coherency was observed from high order of coherency in local HAARP transmissions and their echoes to lower coherency in natural chorus and hiss emissions.

Artificial Aurora Generated by HAARP (Invited)

NASA Astrophysics Data System (ADS)

Streltsov, A. V.; Kendall, E. A.

2013-12-01

We present results from the ionospheric heating experiment conducted on March 12, 2013 at the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. During the experiment HAARP transmitted X-mode 4.57 MHz waves modulated with the frequency 0.9 mHz and pointed in the direction of the magnetic zenith. The beam was focused to ~20 km spot at the altitude 100 km. The heating produces two effects: First, it generates magnetic field-aligned currents producing D and H components of the magnetic field with frequency 0.9 mHz detected by fluxgate magnetometer in Gakona. Second, the heating produced bright luminous structures in the heated region detected with the SRI telescope in 427.8 nm, 557.7 nm, 630.0 nm wavelengths. We emphasize, that for the best of our knowledge, this is the first experiment where the heating of the ionosphere with X-mode produces luminous structures in the ionosphere. We classify this luminosity as an 'artificial aurora', because it correlate with the intensity of the magnetic field-aligned currents, and such correlation is constantly seen in the natural aurora.

Plasma line overshoot Observations during the July 2017 HF campaign at the Arecibo Observatory

NASA Astrophysics Data System (ADS)

Coster, A. J.; Nossa, E.; Kendall, E. A.; Bhatt, A.

2017-12-01

In the 1970's and 80's, enhanced plasma waves were frequently detected by the 430 MHz radar at the Arecibo Observatory within 2 to 8 msec after the HF heater had been turned on (Showen, 1975). This phenomenon is best described as an increase in the return power level of the plasma line by one or two orders of magnitude, followed by a slow decay back to its steady-state value. The formation of short scale striations has frequently been cited as a plausible explanation of the plasma line overshoot. The idea is that as the striations form, they absorb or scatter energy from the HF heater wave. This diminishes the amount of power available to excite the plasma waves detected. Short scale striations are thought to form at the altitude where the frequency of the HF wave matches the upper hybrid resonance - below the altitude of HF reflection. In 1981, the decay of the plasma line overshoot was correlated with the rise of the short scale striations utilizing an HF pulse rate of 4 seconds on/off, with the HF transmitter tuned to 5.1 MHz, and an estimated E.R.P. of 38 MW (Coster et al., 1984). In July 2017, a new series of experiments were performed using the new Arecibo HF facility to reexamine the enhanced plasma line issue, and utilizing the superior diagnostic capabilities available in 2017. These experiments were designed to study possible mechanisms responsible for the formation and decay of the plasma line overshoot. In the experiment, the HF heater was cycled on and off at various sequences including: 8 min on/off, 4 min on/off, and 2 min on/off. The enhanced plasma line was detected throughout the experiment. We will summarize the observations of this experiment, report on the significant findings, and provide suggestions for future experiments.

Using IRI and GSM TIP model results as environment for HF radio wave propagation model during the geomagnetic storm occurred on September 26-29, 2011

NASA Astrophysics Data System (ADS)

Kotova, D. S.; Klimenko, M. V.; Klimenko, V. V.; Zakharov, V. E.; Ratovsky, K. G.; Nosikov, I. A.; Zhao, B.

2015-11-01

This paper analyses the geomagnetic storm on September 26-29, 2011. We compare the calculation results obtained using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) and IRI-2012 (Bilitza et al., 2014) model with ground-based ionosonde data of stations at different latitudes and longitudes. We examined physical mechanisms responsible for the formation of ionospheric effects during the main phase of geomagnetic storm that occurred at the rising phase of the 24th solar cycle. We used numerical results obtained from IRI-2012 and GSM TIP models as propagation environment for HF signals from an equatorial transmitter during quiet and disturbed conditions. We used the model of HF radio wave propagation developed in I. Kant Baltic Federal University (BFU) that is based on the geometrical optics approximation. We compared the obtained radio paths in quiet conditions and during the main and recovery storm phases and evaluated radio wave attenuation in different media models.

MIKON 94. International Microwave Conference (10th) Held in Ksiaz, Poland on May 30-June 2, 1994. Volume 3. Invited Papers

DTIC Science & Technology

1994-01-01

linear non -differential equations in series. This makes it easier to control the result, and an exact and accurate solution is obtained without...battery operated and controlled by an industry standard computer 1161. The HF unit contains a step-recovery diode transmitter and two quasi -TEM antennas...16]. All of these procedures can take advantage of exact non -linear analysis or experimental power characterization and are therefore "full non

Resonant scattering of energetic electrons in the outer radiation belt by HAARP-induced ELF/VLF waves

NASA Astrophysics Data System (ADS)

Chang, Shanshan; Zhu, Zhengping; Ni, Binbin; Cao, Xing; Luo, Weihua

2016-10-01

Several extremely low-frequency (ELF)/very low-frequency (VLF) wave generation experiments have been performed successfully at High-Frequency Active Auroral Research Program (HAARP) heating facility and the artificial ELF/VLF signals can leak into the outer radiation belt and contribute to resonant interactions with energetic electrons. Based on the artificial wave properties revealed by many of in situ observations, we implement test particle simulations to evaluate the effects of energetic electron resonant scattering driven by the HAARP-induced ELF/VLF waves. The results indicate that for both single-frequency/monotonic wave and multi-frequency/broadband waves, the behavior of each electron is stochastic while the averaged diffusion effect exhibits temporal linearity in the wave-particle interaction process. The computed local diffusion coefficients show that, the local pitch-angle scattering due to HARRP-induced single-frequency ELF/VLF whistlers with an amplitude of ∼10 pT can be intense near the loss cone with a rate of ∼10-2 rad2 s-1, suggesting the feasibility of HAARP-induced ELF/VLF waves for removal of outer radiation belt energetic electrons. In contrast, the energy diffusion of energetic electrons is relatively weak, which confirms that pitch-angle scattering by artificial ELF/VLF waves can dominantly lead to the precipitation of energetic electrons. Moreover, diffusion rates of the discrete, broadband waves, with the same amplitude of each discrete frequency as the monotonic waves, can be much larger, which suggests that it is feasible to trigger a reasonable broadband wave instead of the monotonic wave to achieve better performance of controlled precipitation of energetic electrons. Moreover, our test particle scattering simulation show good agreement with the predictions of the quasi-linear theory, confirming that both methods are applied to evaluate the effects of resonant interactions between radiation belt electrons and artificially generated discrete ELF/VLF waves.

Setups for in vitro assessment of RFID interference on pacemakers

NASA Astrophysics Data System (ADS)

Mattei, E.; Censi, F.; Delogu, A.; Ferrara, A.; Calcagnini, G.

2013-08-01

The aim of this study is to propose setups for in vitro assessment of RFID (radiofrequency identification) interference on pacemakers (PM). The voltage induced at the input stage of the PM by low-frequency (LF) and high-frequency (HF) RFID transmitters has been used to quantify the amount of the interference. A commercial PM was modified in order to measure the voltage at its input stage when exposed to a sinusoidal signal at 125 kHz and 13.56 MHz. At both frequencies, two antennas with different dimensions (diameter = 10 cm and 30 cm, respectively) were used to generate the interfering field, and the induced voltage was measured between the lead tip and the PM case (unipolar voltage), and between the tip and ring electrodes (bipolar voltage). The typical lead configurations adopted in similar studies or proposed by international standards, as well as lead paths closer to actual physiological implants were tested. At 125 kHz, the worst-case condition differs for the two antennas: the 10 cm antenna induced the highest voltage in the two-loop spiral configuration, whereas the 30 cm antenna in the 225 cm2 loop configuration. At 13.56 MHz, the highest voltage was observed for both the antennas in the 225 cm2 loop configuration. Bipolar voltages were found to be lower than the unipolar voltages induced in the same configurations, this difference being not as high as one could expect from theoretical considerations. The worst-case scenario, in terms of the induced voltage at the PM input stage, has been identified both for LF and HF readers, and for two sizes of transmitting antennas. These findings may provide the basis for the definition of a standard implant configuration and a lead path to test the EMI effects of LF and HF RFID transmitters on active implantable devices.

High Frequency Propagation modeling in a disturbed background ionosphere: Results from the Metal Oxide Space Cloud (MOSC) experiment

NASA Astrophysics Data System (ADS)

Joshi, D. R.; Groves, K. M.

2015-12-01

The Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud. A host of diagnostic instruments were used to probe and characterize the cloud including the ALTAIR incoherent scatter radar, multiple GPS and optical instruments, satellite radio beacons, and a dedicated network of high frequency (HF) radio links. Data from ALTAIR incoherent scatter radar and HF radio links have been analyzed to understand the impacts of the artificial ionization on radio wave propagation. During the first release the ionosphere was disturbed, rising rapidly and spread F formed within minutes after the release. To address the disturbed conditions present during the first release, we have developed a new method of assimilating oblique ionosonde data to generate the background ionosphere that can have numerous applications for HF systems. The link budget analysis of the received signals from the HF transmitters explains the missing low frequencies in the received signals along the great circle path. Observations and modeling confirm that the small amounts of ionized material injected in the lower-F region resulted in significant changes to the natural propagation environment.

e-POP RRI provides new opportunities for space-based, high-frequency radio science experiments

NASA Astrophysics Data System (ADS)

Burrell, Angeline G.

2017-04-01

Perry et al. (2016, https://doi.org/10.1002/2017JG003855) present the first results of the Radio Receiver Instrument (RRI), a part of the enhanced Polar Outflow Probe (e-POP) that flies on board the CAScade, Smallsat and IOnospheric Polar Explorer satellite. Using a matched filter technique, e-POP RRI was able to observe individual radio pulses transmitted by a ground-based radar. These results were used to examine the temporal variations in the dispersion, polarization, and power of the pulses, demonstrating the capacity for e-POP RRI to contribute to studies of radio propagation at high-frequency (HF) ranges. Understanding radio propagation in the presence and absence of ionospheric irregularities is crucial for ionospheric physics, as well as commercial and military radio applications. Conjunctions between e-POP RRI and ground- or space-based HF transmitters offer a new opportunity for coherent scatter experiments.

Vacuum ultraviolet thin films. I - Optical constants of BaF2, CaF2, LaF3, MgF2, Al2O3, HfO2, and SiO2 thin films. II - Vacuum ultraviolet all-dielectric narrowband filters

NASA Technical Reports Server (NTRS)

Zukic, Muamer; Torr, Douglas G.; Spann, James F.; Torr, Marsha R.

1990-01-01

An iteration process matching calculated and measured reflectance and transmittance values in the 120-230 nm VUV region is presently used to ascertain the optical constants of bulk MgF2, as well as films of BaF2, CaF2, LaF3, MgF2, Al2O3, HfO2, and SiO2 deposited on MgF2 substrates. In the second part of this work, a design concept is demonstrated for two filters, employing rapidly changing extinction coefficients, centered at 135 nm for BaF2 and 141 nm for SiO2. These filters are shown to yield excellent narrowband spectral performance in combination with narrowband reflection filters.

An overview of high-latitude hf induced aurora from EISCAT

NASA Astrophysics Data System (ADS)

Kosch, M.; Gustavsson, B.; Rietveld, M.

The EISCAT HF facility is capable of transmitting over 200 MW into the ionosphere below 5.423 MHz using the low-gain antenna array. Over 1000 MW above 5.423 MHz is available using the high-gain antenna array. During O-mode pumping in the hours after sunset, F-region electrons can be accelerated sufficiently to excite the oxygen atoms and nitrogen molecules, resulting in observable optical emissions at 844.6 (O), 630 (O1D), 557.7 (O1S) and 427.8 (N2) nm above EISCAT. Initial success came in February 1999 with optical recordings by ALIS (Auroral Large Imaging System) from various Swedish locations south of EISCAT and DASI (Digital All-Sky Imager) from Skibotn, Norway, 50 km south-east of EISCAT. Several observations have features unique to high latitudes. Novel discoveries include: (1) Very large electron temperature enhancements of a few 1000 K, which maximise along the magnetic field line direction (2) Ion temperature enhancements of a few 100 K accompanied by large ion outflows, (3) The optical emission usually appears near the magnetic field line direction regardless of the HF transmitter beam pointing direction, (4) The optical emission appears below the HF pump reflection altitude as well as the upper-hybrid resonance height, (5) The optical emission and HF coherent radar backscatter disappears when pumping on the 3rd, 4th or 5th gyro-harmonic frequency, (6) The first artificial optical observations at 844.6 (O) and 427.8 (N2) nm and (7) Annular optical structures, which subsequently collapse into blobs.

Exploiting LF/MF signals of opportunity for lower ionospheric remote sensing

NASA Astrophysics Data System (ADS)

Higginson-Rollins, Marc A.; Cohen, Morris B.

2017-08-01

We introduce a method to diagnose and track the D region ionosphere (60-100 km). This region is important for long-distance terrestrial communication and is impacted by a variety of geophysical phenomena, but it is traditionally very difficult to detect. Modern remote sensing methods used to study the D region are predominately near the very low frequency (VLF, 3-30 kHz) band, with some work also done in the high-frequency and very high frequency bands (HF/VHF, 3-300 MHz). However, the frequency band between VLF and HF has been largely ignored as a diagnostic tool for the ionosphere. In this paper, we evaluate the use of 300 kHz radio reflections as a diagnostic tool for characterizing the D region of the ionosphere. We present radio receiver data, analyze diurnal trends in the signal from these transmitters, and identify ionospheric disturbances impacting LF/MF propagation. We find that 300 kHz remote sensing may allow a unique method for D region diagnostics compared to both the VLF and HF/VHF frequency bands, due to a more direct ionospheric reflection coefficient calculation method with high temporal resolution without the use of forward modeling.

Radio Hazard Safety Assessment for Marine Ship Transmitters: Measurements Using a New Data Collection Method and Comparison with ICNIRP and ARPANSA Limits

PubMed Central

Halgamuge, Malka N.

2015-01-01

We investigated the levels of radio frequency electromagnetic fields (RF EMFs) emitted from marine ship transmitters. In this study, we recorded the radio frequency (RF) electric field (EF) levels emitted from transmitters from a marine vessel focusing on the areas normally occupied by crew members and passengers. Previous studies considered radiation hazard safety assessment for marine vessels with a limited number of transmitters, such as very high-frequency (VHF) transceivers, radar and communication transmitters. In our investigation, EF levels from seven radio transmitters were measured, including: VHF, medium frequency/high frequency (MF/HF), satellite communication (Sat-Com C), AISnavigation, radar X-band and radar S-band. Measurements were carried out in a 40 m-long, three-level ship (upper deck, bridge deck and bridge roof) at 12 different locations. We developed a new data-collection protocol and performed it under 11 different scenarios to observe and measure the radiation emissions from all of the transmitters. In total, 528 EF field measurements were collected and averaged over all three levels of the marine ship with RF transmitters: the measured electric fields were the lowest on the upper deck (0.82–0.86 V/m), the highest on the bridge roof (2.15–3.70 V/m) and in between on the bridge deck (0.47–1.15 V/m). The measured EF levels were then assessed for compliance with the occupational and general public reference levels of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) standards. The ICNIRP and the ARPANSA limits for the general public were exceeded on the bridge roof; nevertheless, the occupational limits were respected everywhere. The measured EF levels, hence, complied with the ICNIRP guidelines and the ARPANSA standards. In this paper, we provide a new data collection model for future surveys, which could be conducted with larger samples to verify our observations. Furthermore, this new method could be useful as a reference for researchers and industry professionals without direct access to the necessary equipment. PMID:25996887

Origin of high photoconductive gain in fully transparent heterojunction nanocrystalline oxide image sensors and interconnects.

PubMed

Jeon, Sanghun; Song, Ihun; Lee, Sungsik; Ryu, Byungki; Ahn, Seung-Eon; Lee, Eunha; Kim, Young; Nathan, Arokia; Robertson, John; Chung, U-In

2014-11-05

A technique for invisible image capture using a photosensor array based on transparent conducting oxide semiconductor thin-film transistors and transparent interconnection technologies is presented. A transparent conducting layer is employed for the sensor electrodes as well as interconnection in the array, providing about 80% transmittance at visible-light wavelengths. The phototransistor is a Hf-In-Zn-O/In-Zn-O heterostructure yielding a high quantum-efficiency in the visible range. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Numerical study of the generation and propagation of ultralow-frequency waves by artificial ionospheric F region modulation at different latitudes

NASA Astrophysics Data System (ADS)

Xu, Xiang; Zhou, Chen; Shi, Run; Ni, Binbin; Zhao, Zhengyu; Zhang, Yuannong

2016-09-01

Powerful high-frequency (HF) radio waves can be used to efficiently modify the upper-ionospheric plasmas of the F region. The pressure gradient induced by modulated electron heating at ultralow-frequency (ULF) drives a local oscillating diamagnetic ring current source perpendicular to the ambient magnetic field, which can act as an antenna radiating ULF waves. In this paper, utilizing the HF heating model and the model of ULF wave generation and propagation, we investigate the effects of both the background ionospheric profiles at different latitudes in the daytime and nighttime ionosphere and the modulation frequency on the process of the HF modulated heating and the subsequent generation and propagation of artificial ULF waves. Firstly, based on a relation among the radiation efficiency of the ring current source, the size of the spatial distribution of the modulated electron temperature and the wavelength of ULF waves, we discuss the possibility of the effects of the background ionospheric parameters and the modulation frequency. Then the numerical simulations with both models are performed to demonstrate the prediction. Six different background parameters are used in the simulation, and they are from the International Reference Ionosphere (IRI-2012) model and the neutral atmosphere model (NRLMSISE-00), including the High Frequency Active Auroral Research Program (HAARP; 62.39° N, 145.15° W), Wuhan (30.52° N, 114.32° E) and Jicamarca (11.95° S, 76.87° W) at 02:00 and 14:00 LT. A modulation frequency sweep is also used in the simulation. Finally, by analyzing the numerical results, we come to the following conclusions: in the nighttime ionosphere, the size of the spatial distribution of the modulated electron temperature and the ground magnitude of the magnetic field of ULF wave are larger, while the propagation loss due to Joule heating is smaller compared to the daytime ionosphere; the amplitude of the electron temperature oscillation decreases with latitude in the daytime ionosphere, while it increases with latitude in the nighttime ionosphere; both the electron temperature oscillation amplitude and the ground ULF wave magnitude decreases as the modulation frequency increases; when the electron temperature oscillation is fixed as input, the radiation efficiency of the ring current source is higher in the nighttime ionosphere than in the daytime ionosphere.

Remote sensing of mesospheric dust layers using active modulation of PMWE by high-power radio-waves

NASA Astrophysics Data System (ADS)

Cohen, M.; Zhang, X.; Cohen, M.; Mahmoudian, A.; Scales, W.; Kosch, M. J.; M Farahani, M.; Mohebalhojeh, A.

2016-12-01

So-called polar mesospheric winter echoes (PMWE) are radar echoes observed during winter at altitudes around 50-80 km and are much weaker than their PMSE (Polar Mesospheric Summer Echoes) counterpart. Unlike PMSE, PMWE are less studied and understood. Breaking of gravity waves and the associated turbulence are proposed as the major source for PMWE echoes. The action of neutral turbulence alone does not appear to give a good explanation for PMWE. PMWE is also attributed to Bragg scatter from electron irregularities which result from charging of free electrons onto sub-visible particles. The temporal behavior of PMWE response to HF pump heating can be employed to diagnose the charged dust layer. Specifically, the rise and fall time of radar echo strength as well as relaxation and recovery time after heater turn-on and off are distinct parameters that are a function of radar frequency. This work presents the first study of the modulation of PMWE by artificial radiowave heating using computational modeling and experimental observation in different radar frequency bands. Variation of dust plasma parameters associated with PMWE such as dust radius, dust density, recombination rate, electron- and dust-neutral collision frequencies, photo-detachment current and electron temperature enhancement ratio are included. Computational results derived from different sets of parameters are considered and compared with recent observations at EISCAT using 224 MHz and 56 MHz radars. The agreement between the model results and the observations show the high potential of remote sensing of dust and plasma parameters associated with PMWE. Measurement of Te/Ti using ISR and simultaneous observations in two frequency bands may lead to a more accurate estimation of dust density and radius. The enhancement of backscattered signal in the HF band during PMWE heating is predicted for the first time. The required background dust-plasma parameters as well as heater power (Te/Ti) for the observation of turn-on overshoot are investigated. It has been shown that the similarity of the temporal evolution of radar echoes in HF band and average charge on the dust particles can be used to study the fundamental physics associated with the dust charging in the PMWE source region. The possibilities of perusing PMWE heating experiments at HAARP will be discussed.

TID measurement using oblique transmissions of HF pulses

NASA Astrophysics Data System (ADS)

Galkin, Ivan; Reinisch, Bodo; Huang, Xueqin; Paznukhov, Vadym; Hamel, Ryan; Kozlov, Alexander; Belehaki, Anna

2017-04-01

The Traveling Ionospheric Disturbance (TID), a wave-like signature of moving plasma density modulation in the ionosphere, is widely acknowledged for its utility in backtracking the anomalous events responsible for the TID generation, and as a major inconvenience to high-frequency (HF) operational systems because of its deleterious impact on the accuracy of navigation and geolocation. The pilot project "Net-TIDE" for the real-time detection and evaluation of TIDs began its operation in 2016 based on the remote-sensing data from synchronized, network-coordinated HF sounding between pairs of DPS4D ionosondes at five participating observatories in Europe. Measurement of all signal properties (Doppler frequency, angle of arrival, and time-of-flight from transmitter to receiver) proved to be instrumental in detecting the TID and deducing the TID parameters: amplitude, wavelength, phase velocity, and direction of propagation. Processing of the measured HF signal data required a specialized signal processing technique that is capable of consistently extracting different signals that have propagated along different ionospheric paths. The multi-path signal environment proved to be the greatest challenge for the reliable TID specification by Net-TIDE, demanding the development of an intelligent system for "signal tracking". The intelligent system is based on a neural network model of a pre-attentive vision capable of extracting continuous signal tracks from the multi-path signal ensemble. Specific examples of the Net-TIDE algorithm suite operation and its suitability for a fully automated TID warning service are discussed.

Radiation damage effects in far-ultraviolet filters, thin films, and substrates.

PubMed

Keffer, C E; Torr, M R; Zukic, M; Spann, J F; Torr, D G; Kim, J

1994-09-01

Advances in vacuum ultraviolet thin-film filter technology have been made through the use of filter designs with multilayers of materials such as Al(2)O(3), BaF(2), CaF(2), HfO(2), LaF(3), MgF(2), and SiO(2). Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 × 9 R(E) orbit will expose the instrument to approximately 250 krad of radiation. Because to our knowledge no previous studies have been made on the potential radiation damage of these materials in the thin-film format, we report on such an assessment here. Transmittances and reflectances of BaF(2), CaF(2), HfO(2), MgF(2), and SiO(2) thin films on MgF(2) substrates, Al(2)O(3) thin films on fused-silica substrates, uncoated fused silica and MgF(2), and four multilayer filters made from these materials were measured from 120 to 180 nm beforeand after irradiation by 250 krad from a (60)Co gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 to 300 nm indicates 2-5% radiation-induced absorption near 260 nm in some of the samples with MgF(2) substrates. From these measurements we conclude that far-ultraviolet filters made from the materials tested should experience less than 5% change from exposure to up to 250 krad of high-energy radiation in space applications.

Radiation Damage Effects in Far Ultraviolet Filters and Substrates

NASA Technical Reports Server (NTRS)

Keffer, Charles E.; Torr, Marsha R.; Zukic, Muamer; Spann, James F.; Torr, Douglas G.; Kim, Jongmin

1993-01-01

New advances in VUV thin film filter technology have been made using filter designs with multilayers of materials such as Al2O3, BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2. Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 X 9 R(sub E) orbit will expose the instrument to approximately 275 krads of radiation. In view of the fact that no previous studies have been made on potential radiation damage of these materials in the thin film format, we report on such an assessment here. Transmittances and reflectances of BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2 thin films on MgF2 substrates, Al2O3 thin films on fused silica substrates, uncoated fused silica and MgF2, and four multilayer filters made from these materials were measured from 120 nm to 180 nm before and after irradiation by 250 krads from a Co-60 gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 nm to 300 nm indicated a 3 - 5% radiation-induced absorption near 260 nm in some of the samples with MgF2 substrates. From these measurements it is concluded that far ultraviolet filters made from the materials tested should experience less that 5% change from exposure to up to 250 krads of high energy radiation in space applications.

The spatial distribution of VLF transmitters at topside ionosphere and the VLF-induced heating phenomena

NASA Astrophysics Data System (ADS)

Zhang, X.; Zhao, S.; Zhou, C.

2016-12-01

Based on the electric field observation at VLF frequency band onboard DEMETER satellite, the spatial distribution was studied about some VLF transmitters at different latitudes on ground, as while the maximal intensity, the attenuation rate and affected areas, including NWC and GBZ with high power, and some transmitters with low radiated power. As while the full wave propagation model is used to simulate the theoretical results at topside ionosphere. The results show that, (1) the intensity of electromagnetic waves at topside ionosphere with 1000kW radiated power is higher as one or two orders of magnitude than those with 500 kW power; (2) at same station, the amplitudes in electric field are larger with high frequency signals than those lower ones at the same station; (3) at same frequency points, the ionospheric background affected strongly the waves penetrating into the ionosphere, for the intensity of same frequency signals differed apparently at different transmitters. Due to the high energy of VLF transmitters, the heating phenomena were also observed extensively at DEMETER satellite. Here the VLF-induced ionospheric heating perturbations were selected and analyzed during the solar minimum years of 2008-2009. There are three main features in VLF heating, (1) the temperature of electron and ion increased, while the electron density and O+ density at topside ionosphere decreased; (2) the low hybrid waves were excited at 10-20kHz; (3) the plasma frequency was emitted at some points around 1.92MHz; (4) the VLF induced heating phenomena were associated closely with the radiated power of transmitters, while the transmitters with power <500kW are hard to cause the ionospheric disturbances directly. Considering the propagation and heating process of VLF electromagnetic wave, these features above were discussed and compared with HF heating processes. By learning for the man-made signals propagating from ground into ionosphere, it is helpful to further understand the coupling mechanism among different earth spheres. Acknowledgement: This paper is supported by the International Cooperation Project (2014DFR21280).

Fabrication of broadband quasi-omnidirectional antireflective surface on glass for photovoltaic application

NASA Astrophysics Data System (ADS)

Kumar, Arvind; Kumar, Praveen; Srinivas, G.; Jakeer Khan G., H.; Siju, Barshilia, Harish C.

2016-05-01

In this paper, we have demonstrated a simple and cost effective HF-vapor phase etching method to fabricate the broadband quasi-omnidirectional antireflective surface on glass substrate. Both-sides etched sodalime glass substrates under optimized conditions showed a broadband enhancement in the transmittance spectra with maximum transmittance as high as ~97% at 598 nm. FESEM results confirmed the formation of a graded nanoporous surface, which lowers it refractive index. The etched surface exhibited excellent AR property over a wide range of incidence angles (8°-48°), which is attributed due to the formation of graded porosity. Silicon solar cell covered with plain glass showed Isc of 0.123A and efficiency of 8.76%, while it showed Isc of 0.130A and efficiency of 9.2% when it was covered by etched glass. Furthermore, it exhibited an excellent anti-soiling property as compared to plain glass. All these results show its strong potential in the photovoltaic application.

Bottomside Ionospheric Electron Density Specification using Passive High Frequency Signals

NASA Astrophysics Data System (ADS)

Kaeppler, S. R.; Cosgrove, R. B.; Mackay, C.; Varney, R. H.; Kendall, E. A.; Nicolls, M. J.

2016-12-01

The vertical bottomside electron density profile is influenced by a variety of natural sources, most especially traveling ionospheric disturbances (TIDs). These disturbances cause plasma to be moved up or down along the local geomagnetic field and can strongly impact the propagation of high frequency radio waves. While the basic physics of these perturbations has been well studied, practical bottomside models are not well developed. We present initial results from an assimilative bottomside ionosphere model. This model uses empirical orthogonal functions based on the International Reference Ionosphere (IRI) to develop a vertical electron density profile, and features a builtin HF ray tracing function. This parameterized model is then perturbed to model electron density perturbations associated with TIDs or ionospheric gradients. Using the ray tracing feature, the model assimilates angle of arrival measurements from passive HF transmitters. We demonstrate the effectiveness of the model using angle of arrival data. Modeling results of bottomside electron density specification are compared against suitable ancillary observations to quantify accuracy of our model.

HAARP diesel engine-generator(s) noise study

DOT National Transportation Integrated Search

2005-01-07

This document presents the results and corresponding analysis of an outdoor noise measurement program conducted by the John A. Volpe National Transportation Systems Centers Acoustic Facility (Volpe Center) at the United States Air Forces High F...

ULF Generation by Modulated Ionospheric Heating

NASA Astrophysics Data System (ADS)

Chang, C.; Labenski, J.; Wallace, T.; Papadopoulos, K.

2013-12-01

Modulated ionospheric heating experiments designed to generate ULF waves using the HAARP heater have been conducted since 2007. Artificial ULF waves in the Pc1 frequency range were observed from space and by ground induction magnetometers located in the vicinity of the heater as well as at long distances. Two distinct generation mechanisms of artificial ULF waves were identified. The first was electroject modulation under geomagnetically disturbed conditions. The second was pressure modulation in the E and F regions of the ionosphere under quiet conditions. Ground detections of ULF waves near the heater included both Shear Alfven waves and Magnetosonic waves generated by electrojet and/or pressure modulations. Distant ULF detections involved Magnetosonic wave propagation in the Alfvenic duct with pressure modulation as the most likely source. Summary of our observations and theoretical interpretations will be presented at the meeting. We would like to acknowledge the support provided by the staff at the HAARP facility during our ULF experiments.

First results of mapping sporadic E with a passive observing network

NASA Astrophysics Data System (ADS)

Rice, D. D.; Sojka, J. J.; Eccles, J. V.; Raitt, J. W.; Brady, J. J.; Hunsucker, R. D.

2011-12-01

Sporadic E (Es) can have dramatic effects on communications in the HF and low VHF range, producing over-the-horizon propagation for signals normally restricted to line-of-sight, and sometimes blocking F region propagation of signals in the lower HF range. Measuring the E region winds believed to produce Es is difficult, and no practical means of predicting Es occurrence currently exists other than statistical models. We describe a low-cost observing network based on software-controlled receivers that continuously watches for Es in near-real time using oblique HF propagation from existing transmitters. Results from an 11-day pilot campaign in July 2008 demonstrated that even a limited number of receivers in the network can readily determine the presence and extent of Es patches. These observations indicate that Es often develops quickly over regions of several hundred kilometers rather than gradually drifting across an area. These widespread Es “blooms” have been observed near winter solstice and occasionally at other times of the year; their lifetime depends on the season but can be several hours during the summer. The current network allows the extent of Es in portions of North America to be evaluated: the geographical distribution of Es and bounds on the density of the layer are inferred from its effects on the ionospheric maximum usable frequency (MUF). This study demonstrates quantitatively that Es mapping can provide information about Es layer geographical growth and decay. The observed sudden widespread Es blooms are space weather events that can have significant impact on HF/lower VHF communications and propagation model predictions.

Comparison of fabrication methods for microstructured deep UV multimode waveguides based on fused silica

NASA Astrophysics Data System (ADS)

Elmlinger, Philipp; Schreivogel, Martin; Schmid, Marc; Kaiser, Myriam; Priester, Roman; Sonström, Patrick; Kneissl, Michael

2016-04-01

The suitability of materials for deep ultraviolet (DUV) waveguides concerning transmittance, fabrication, and coupling properties is investigated and a fused silica core/ambient air cladding waveguide system is presented. This high refractive index contrast system has far better coupling efficiency especially for divergent light sources like LEDs and also a significantly smaller critical bending radius compared to conventional waveguide systems, as simulated by ray-tracing simulations. For the fabrication of 300-ffm-thick multimode waveguides a hydrouoric (HF) acid based wet etch process is compared to selective laser etching (SLE). In order to fabricate thick waveguides out of 300-ffm-thick silica wafers by HF etching, two masking materials, LPCVD silicon nitride and LPCVD poly silicon, are investigated. Due to thermal stress, the silicon nitride deposited wafers show cracks and even break. Using poly silicon as a masking material, no cracks are observed and deep etching in 50 wt% HF acid up to 180 min is performed. While the masked and unmasked silica surface is almost unchanged in terms of roughness, notching defects occur at the remaining polysilicon edge leading to jagged sidewalls. Using SLE, waveguides with high contour accuracy are fabricated and the DUV guiding properties are successfully demonstrated with propagation losses between 0.6 and 0:8 dB=mm. These values are currently limited by sidewall scattering losses.

Biological satellite scientific devices

NASA Astrophysics Data System (ADS)

Perepech, B. L.; Rumiantsev, V. P.; Galkin, V. M.; Shakhvorostov, S. V.; Rvachev, S. S.

1991-02-01

The paper describes the NA SBS 9 systems developed for the ninth Cosmos-2044 biological test mission. The NA SBS 9 life support systems designed for monkeys and rats follow standard design of BIOS-Vivarium and BIOS-Primate units. The main features of NA SBS 9 include the use of a recently developed HF physiological data recorder Skat-3; the incorporation into BIOS-Primate of two units intended for biorhythmic studies (the BBI-Zh system for studying beetles and the VITALOG developed by NASA for studies on monkeys); and a new version of BIOS-Primate system incorporating a capacitance-link and an inductance-link temperature transmitters and a brain tissue oxygen tension control channel.

Physical property improvement of IZTO thin films using a hafnia buffer layer

NASA Astrophysics Data System (ADS)

Park, Jong-Chan; Kang, Seong-Jun; Choi, Byeong-Gyun; Yoon, Yung-Sup

2018-01-01

Hafnia (HfO2) has excellent mechanical and chemical stability, good transmittance, high dielectric constant, and radiation resistance property; thus, it can prevent impurities from permeating into the depositing films. So, we deposited hafnia films with various thicknesses in the range of 0-60 nm on polyethylene naphthalate (PEN) substrates before depositing indium-zinc-tin oxide (IZTO) thin films on them using RF magnetron sputtering, and their structural, morphological, optical, and electrical properties were evaluated. All IZTO thin films were successfully deposited without cracks or pinholes and had amorphous structures. As the thickness of the hafnia film increased to 30 nm, the overall properties improved; a surface roughness of 2.216 nm, transmittance of 82.59% at 550 nm, resistivity of 5.66 × 10-4 Ω cm, sheet resistance of 23.60 Ω/sq, and figure of merit of 6.26 × 10-3 Ω-1 were realized. These results indicate that the structure and materials studied in this research are suitable for application in flexible transparent electronic devices such as organic light emitting diodes, liquid crystal displays, touch panels, and solar cells.

The NASA B-757 HIRF Test Series: Flight Test Results

NASA Technical Reports Server (NTRS)

Moeller, Karl J.; Dudley, Kenneth L.

1997-01-01

In 1995, the NASA Langley Research Center conducted a series of aircraft tests aimed at characterizing the electromagnetic environment (EME) in and around a Boeing 757 airliner. Measurements were made of the electromagnetic energy coupled into the aircraft and the signals induced on select structures as the aircraft was flown past known RF transmitters. These measurements were conducted to provide data for the validation of computational techniques for the assessment of electromagnetic effects in commercial transport aircraft. This paper reports on the results of flight tests using RF radiators in the HF, VHF, and UHF ranges and on efforts to use computational and analytical techniques to predict RF field levels inside the airliner at these frequencies.

Effects of proton irradiation on thin-film materials for optical filters

NASA Astrophysics Data System (ADS)

Scaglione, Salvatore; Piegari, Angela; Sytchkova, Anna; Jakšić, Milko

2017-11-01

The behaviour of interference optical filters for space applications has been investigated under low energy proton irradiation. In order to understand the behaviour of the interference coating subjected to proton irradiation, the interaction of protons with coating and substrate was simulated by the SRIM code. A beam of protons of 60 KeV with an integrated fluence of 1013 p+/cm2 was used. The spectral transmittances of fused silica, TiO2 and HfO2 single layers and interference coatings were measured before and after irradiation and, according to simulations, no significant effects were detected in the visible-near infrared spectrum, while some variations appeared at shorter wavelengths.

Effects on transionospheric HF propagation observed by ISIS at middle and auroral latitudes

NASA Astrophysics Data System (ADS)

James, H. G.

2006-01-01

In 1978, an experiment on transionospheric HF propagation was carried out using a transmitter at Ottawa and the sounder receivers of the ISIS-I and ISIS-II spacecraft. Over 100 ISIS-II passes were successfully recorded using a fixed frequency of 9.303 MHz. A survey of the data has allowed some reproducible characteristics of transionospheric propagation to be identified. A number of ISIS-II ionograms are published here to illustrate those characteristics. A systematic feature of the pulses is their partial splitting into ordinary (O) and extraordinary (X) parts, producing a tripartite compound pulse at the satellite. Equatorward pulses are comparatively sharp and occasionally exhibit periodic fades with beat frequencies between about 1 and 4 Hz. Features of the fades indicate that focussing of rays is a better explanation for the fades than diffraction. Rays near the limits of the reception zone can result in dispersed pulses, thought to indicate forward scattering. Swept-frequency ionograms interleaved with fixed-frequency measurements allowed two-dimensional density distributions to be modeled in altitude and latitude. Three-dimensional ray tracing plus a Newton’s-iteration algorithm were used to find rays that connected the transmitter with the position of the satellite at any time along its path. The latitudinal extent of the zone irradiated at ISIS-II altitude thus computed is approximately as observed, albeit sensitively dependent upon north south density gradients. Within this “iris” of accessibility, the maximum intensity of waves recorded at the spacecraft is within 10 dB of what is computed with a link calculation based on ray optics, but there are many dropouts of 20 30 dB below this maximum envelope. Toward the equator, propagation directions come to within about 10° of the magnetic-field axis. This research supports planning for coordinated ground-space radio experiments in the upcoming e-POP satellite mission.

Effects on transionospheric HF propagation observed by ISIS at middle and auroral latitudes

NASA Astrophysics Data System (ADS)

James, G.

During the months of May through July 1978, an experiment on transionospheric HF propagation was carried out using a transmitter at Ottawa and the sounder receivers of the ISIS-I and ISIS-II spacecraft. Fixed- and synchronous swept-frequency recordings were made. Over 100 ISIS-II passes were successfully recorded at 9.303 MHz, the highest fixed frequency of receiver operation. Several tens of these passes have been analyzed in an attempt to establish the salient characteristics of the propagation. From these characteristics, the goal is to improve understanding of the processes experienced by waves passing through the ionosphere, e.g., focusing or scattering. This research supports planning for coordinated ground-space radio experiments in the upcoming Enhanced Polar Outflow Probe satellite mission, to be flown for the Canadian Space Agency. Swept-frequency ionograms interleaved with the aforementioned fixed-frequency measurements allowed two-dimensional density distributions to be modeled in altitude and latitude. Computer code was developed for three-dimensional ray tracing. A Newton's-iteration algorithm was used for efficient searches for solution rays that connect the transmitter with the position of the satellite at any time along its path. The latitudinal extent of the zone irradiated at ISIS-II altitude thus computed is approximately as observed, albeit sensitively dependent upon north-south density gradients. Within this "iris" of accessibility, the peak intensity of waves recorded at the spacecraft is within 10 dB of that found with a link calculation based on ray optics. Density inhomogeneities influence the transmitted O and X mode waves, in various ways. Poleward rays result in dispersed pulses, indicating quasi-perpendicular propagation that is forward scattered. Toward the equator, propagation directions come to within about 10 of the magnetic-field axis. Equatorward pulses are comparatively sharp and occasionally exhibit periodic fades with beat frequencies between about 1 and 4 Hz. Features of the fades indicate that focusing of rays is a better explanation for the fades than diffraction.

Space weather and HF propagation along different paths of the Russian chirp sounders network

NASA Astrophysics Data System (ADS)

Kurkin, V. I.; Litovkin, G. I.; Matyushonok, S. M.; Vertogradov, G. G.; Ivanov, V. A.; Poddelsky, I. N.; Rozanov, S. V.; Uryadov, V. P.

This paper presents experimental data obtained on long paths (from 2200 km to 5700 km range) of Russian frequency modulated continues wave (chirp) sounders network for the period from 1998 to 2003. Four transmitters (near Magadan, Khabarovsk, Irkutsk, Norilsk) and four receivers (near Irkutsk, Yoshkar-Ola, Nizhny Novgorod, Rostov-on-Don) were combined into single network to investigate a influence of geomagnetic storms and substorms on HF propagation in Asian region of Russia. In this region the geographic latitudes are in greatest excess of magnetic latitudes. As a consequence, elements of the large-scale structure, such as the main ionospheric trough, and the zone of auroral ionization, are produced in the ionosphere at the background of a low electron ionization. Coordinated experiments were carried out using 3-day Solar-Geophysical activity forecast presented by NOAA Space Environment Center in Internet. Sounding operations were conducted in the frequency band 4 -- 30 MHz on a round-the-clock basis at 15-min intervals. Oblique-incidence sounding (OIS) ionograms were recorded during 5-7 days every season for some years. The comparison between experimental data and simulation of OIS ionograms using International Reference Ionospheric model (IRI-2001) allowed to estimate the forecast of HF propagation errors both under quiet condition and during geomagnetic disturbances. Strong deviations from median values of maximum observed frequencies on mid-latitude paths in daytime present a real challenge to ionospheric forecast. Subauroral and mid-latitude chirp-sounding paths run, respectively, near the northward and southward walls of the main ionospheric trough. This make sit possible to study the dynamics of the trough's boundaries under different geophysical conditions and assess the influence of ionization gradients and small-scale turbulence on HF signal characteristics. The signals off-great circle propagation were registered over a wide frequency range and for long time intervals during a moderate geomagnetic disturbances and storms. .

Study of the morphology of ZnS thin films deposited on different substrates via chemical bath deposition.

PubMed

Gómez-Gutiérrez, Claudia M; Luque, P A; Castro-Beltran, A; Vilchis-Nestor, A R; Lugo-Medina, Eder; Carrillo-Castillo, A; Quevedo-Lopez, M A; Olivas, A

2015-01-01

In this work, the influence of substrate on the morphology of ZnS thin films by chemical bath deposition is studied. The materials used were zinc acetate, tri-sodium citrate, thiourea, and ammonium hydroxide/ammonium chloride solution. The growth of ZnS thin films on different substrates showed a large variation on the surface, presenting a poor growth on SiO2 and HfO2 substrates. The thin films on ITO substrate presented a uniform and compact growth without pinholes. The optical properties showed a transmittance of about 85% in the visible range of 300-800 nm with band gap of 3.7 eV. © Wiley Periodicals, Inc.

HAARP 2011 Summer Student Research Campaign

DTIC Science & Technology

2012-10-16

in order to take advantage of a wide variety of background ionospheric conditions and to provide ample time for each student to investigate...The SSRC expands on the PARS Summer School by providing a significant increase in facility operational time. This has advantages in several areas...in several advantages for scheduling and conducting experiments: (1) Higher ionospheric density yields higher F-region critical frequency (foF2

In-situ Measurements of the Direction of Propagation of Pump Waves

NASA Astrophysics Data System (ADS)

James, H. G.; Bernhardt, P. A.; Leyser, T.; Siefring, C. L.

2017-12-01

In the course of an experiment to modify the ionosphere, the direction of pump wave propagation is affected by density gradients in the horizontal and vertical directions, fundamentally affecting wave-energy transport. Horizontal gradients on various scales may await a modification attempt as a preexisting state of the ionosphere and/or be changed by the deposition of heater radio-frequency energy. In the results from the Radio Receiver Instrument (RRI) in the enhanced Polar Outflow Probe (e-POP), we have recorded on the order of 100 flights over ionospheric heaters revealing a variety of processes that high-frequency pump waves experience in the ionosphere. E-POP flies on the Canadian satellite CASSIOPE in an elliptic (320 x 1400 km), highly-inclined (81°) orbit. High frequency measurements have been/are being made near SPEAR, HAARP, Sura, EISCAT Heating and Arecibo. Electromagnetic waves from ground-based heaters are detected by the two, orthogonal, 6-m dipoles on the RRI. The high input impedance of the RRI means that the dipoles act as voltage probes, from which the electric field of incoming waves can be simply computed. When combined with cold-magnetoplasma electric-field theory, the relationship of voltages on the two orthogonal dipoles is used to deduce the direction of arrival of an incoming wave in three dimensions. We illustrate the technique by its application to analysis of signals from different transmitters. These results show a variety of pump-wave propagation directions, indicating the complexity of density structure within which modification might take place. Such complexity illustrates the importance of three-dimensional models of density in the vicinity of modification.

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wong, Alfred Y.

1999-09-20

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from themore » self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO{sub 2} through the use of ion cyclotron resonant heating.« less

Nonlinear interactions of electromagnetic waves with the auroral ionosphere

NASA Astrophysics Data System (ADS)

Wong, Alfred Y.

1999-09-01

The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field. To take advantage of this giant outdoor laboratory, two facilities HAARP and HIPAS, with frequencies ranging from the radio to optical bands, are now available for active probing of and interaction with this interesting region. The ponderomotive pressures from the self-consistent wave fields have produced significant local perturbations of density and particle distributions at heights where the incident EM frequency matches a plasma resonance. This paper will review theory and experiments covering the nonlinear phenomena of parametric decay instability to wave collapse processes. At HF frequencies plasma lenses can be created by preconditioning pulses to focus what is a normally divergent beam into a high-intensity spot to further enhance nonlinear phenomena. At optical wavelengths a large rotating liquid metal mirror is used to focus laser pulses up to a given height. Such laser pulses are tuned to the same wavelengths of selected atomic and molecular resonances, with resulting large scattering cross sections. Ongoing experiments on dual-site experiments and excitation of ELF waves will be presented. The connection of such basic studies to environmental applications will be discussed. Such applications include the global communication using ELF waves, the ozone depletion and remediation and the control of atmospheric CO2 through the use of ion cyclotron resonant heating.

Space weather effects on airline communications in the high latitude regions

NASA Astrophysics Data System (ADS)

Stocker, Alan; Siddle, Dave; Warrington, Mike; Honary, Farideh; Zaalov, Nikolay; Homam, Mariyam; Boteler, David; Danskin, Donald; de Franceschi, Georgiana; Ascaneus, Svend

2013-04-01

In the polar regions, ground-based VHF facilities for air-traffic control are lacking (and non-existent on the Russian side of the pole) and satellite communication systems either not available or expensive to retrofit to current aircraft and hence there remains a need for HF communication systems. Unfortunately, at these latitudes space weather can significantly affect the propagation of HF radio signals and the forecasting techniques currently employed by the airline industry are somewhat crude. In this paper, a new project that aims to provide forecasting of HF propagation characteristics for use by civilian airlines operating over polar routes will be described and preliminary results presented. Previous work in this area [e.g. Stocker et al., 2007] has focussed on taking HF signal measurements (e.g. SNR, delay and Doppler spread, and direction of arrival) on a limited number of propagation paths and developing an ionospheric model that incorporates high latitude features (e.g. polar patches and arcs) which, when combined with raytracing, allows the broad characteristics of the observations to be reproduced [Warrington et al., 2012]. The new project will greatly extend this work and consists of a number of stages. Firstly, HF measurements from an extensive network of purpose built transmitters and receivers spanning the Arctic regions will be collected and analysed. In order to test a wide variety of scenarios, the propagation paths will have different characteristics, e.g. different lengths and covering different parts of the northern ionosphere (i.e. polar cap paths where both terminals are in the polar cap, trans-auroral paths, and sub-auroral paths) and observations will be taken at a range of HF frequencies for a period covering the current (so far weak) solar maximum and part of the declining phase. Simultaneously, high latitude absorption measurements utilising the Global Riometer Array (GLORIA) will be collected and analysed. Next, the observations of the signal characteristics (i.e. both reflection and absorption properties) will be related to prevailing space weather parameters. Following on from this, an auroral absorption prediction model based on solar wind and interplanetary data will be developed together with the further refinement of the existing ionospheric model taking into account the new observations and adding auroral and polar cap absorption models. Algorithms for nowcasting and forecasting of radio propagation conditions for trans-polar aircraft will then be developed from the ionospheric model. In addition to the approach described above, the benefits of ground station diversity using both the experimental data and the models developed during the project will also be investigated. Stocker A.J., E.M. Warrington, and D.R. Siddle, Comparison between the measured and predicted parameters of HF radio signals propagating along the mid-latitude trough and within the polar cap, Radio Science, 42, RS3019, doi:10.1029/2006RS003557, 2007. Warrington EM, Zaalov NY, Stocker AJ, Naylor JS, HF propagation modelling within the polar ionosphere, Radio Science, 47, Article number RS0L13, doi:10.1029/2011RS004909, 2012.

In-situ Calibration Methods for Phased Array High Frequency Radars

NASA Astrophysics Data System (ADS)

Flament, P. J.; Flament, M.; Chavanne, C.; Flores-vidal, X.; Rodriguez, I.; Marié, L.; Hilmer, T.

2016-12-01

HF radars measure currents through the Doppler-shift of electromagnetic waves Bragg-scattered by surface gravity waves. While modern clocks and digital synthesizers yield range errors negligible compared to the bandwidth-limited range resolution, azimuth calibration issues arise for beam-forming phased arrays. Sources of errors in the phases of the received waves can be internal to the radar system (phase errors of filters, cable lengths, antenna tuning) and geophysical (standing waves, propagation and refraction anomalies). They result in azimuthal biases (which can be range-dependent) and beam-forming side-lobes (which induce Doppler ambiguities). We analyze the experimental calibrations of 17 deployments of WERA HF radars, performed between 2003 and 2012 in Hawaii, the Adriatic, France, Mexico and the Philippines. Several strategies were attempted: (i) passive reception of continuous multi-frequency transmitters on GPS-tracked boats, cars, and drones; (ii) bi-static calibrations of radars in mutual view; (iii) active echoes from vessels of opportunity of unknown positions or tracked through AIS; (iv) interference of unknown remote transmitters with the chirped local oscillator. We found that: (a) for antennas deployed on the sea shore, a single-azimuth calibration is sufficient to correct phases within a typical beam-forming azimuth range; (b) after applying this azimuth-independent correction, residual pointing errors are 1-2 deg. rms; (c) for antennas deployed on irregular cliffs or hills, back from shore, systematic biases appear for some azimuths at large incidence angles, suggesting that some of the ground-wave electromagnetic energy propagates in a terrain-following mode between the sea shore and the antennas; (d) for some sites, fluctuations of 10-25 deg. in radio phase at 20-40 deg. azimuthal period, not significantly correlated among antennas, are omnipresent in calibrations along a constant-range circle, suggesting standing waves or multiple paths in the presence of reflecting structures (buildings, fences), or possibly fractal nature of the wavefronts; (e) amplitudes lack stability in time and azimuth to be usable as a-priori calibrations, confirming the accepted method of re-normalizing amplitudes by the signal of nearby cells prior to beam-forming.

Creating Space Plasma from the Ground

DTIC Science & Technology

2016-05-12

estimated a GW ERP of rf energy would produce an ionosphere half that from an overhead sun, assuming ~15% efficiency conversion of rf energy to...rf energy would produce an ionosphere half that from an overhead sun, assuming ~15% efficiency conversion of rf energy to accelerated electron energy...altitudes along the HAARP field line indicated); images of artificial optical emissions as viewed looking upwards along the magnetic field line from

Preparation and characterizations of SnO2 nanopowder and spectroscopic (FT-IR, FT-Raman, UV-Visible and NMR) analysis using HF and DFT calculations.

PubMed

Ayeshamariam, A; Ramalingam, S; Bououdina, M; Jayachandran, M

2014-01-24

In this work, pure and singe phase SnO2 Nano powder is successfully prepared by simple sol-gel combustion route. The photo luminescence and XRD measurements are made and compared the geometrical parameters with calculated values. The FT-IR and FT-Raman spectra are recorded and the fundamental frequencies are assigned. The optimized parameters and the frequencies are calculated using HF and DFT (LSDA, B3LYP and B3PW91) theory in bulk phase of SnO2 and are compared with its Nano phase. The vibrational frequency pattern in nano phase gets realigned and the frequencies are shifted up to higher region of spectra when compared with bulk phase. The NMR and UV-Visible spectra are simulated and analyzed. Transmittance studies showed that the HOMO-LUMO band gap (Kubo gap) is reduced from 3.47 eV to 3.04 eV while it is heated up to 800°C. The Photoluminescence spectra of SnO2 powder showed a peak shift towards lower energy side with the change of Kubo gap from 3.73 eV to 3.229 eV for as-prepared and heated up to 800°C. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Interface Engineering with MoS2 -Pd Nanoparticles Hybrid Structure for a Low Voltage Resistive Switching Memory.

PubMed

Wang, Xue-Feng; Tian, He; Zhao, Hai-Ming; Zhang, Tian-Yu; Mao, Wei-Quan; Qiao, Yan-Cong; Pang, Yu; Li, Yu-Xing; Yang, Yi; Ren, Tian-Ling

2018-01-01

Metal oxide-based resistive random access memory (RRAM) has attracted a lot of attention for its scalability, temperature robustness, and potential to achieve machine learning. However, a thick oxide layer results in relatively high program voltage while a thin one causes large leakage current and a small window. Owing to these fundamental limitations, by optimizing the oxide layer itself a novel interface engineering idea is proposed to reduce the programming voltage, increase the uniformity and on/off ratio. According to this idea, a molybdenum disulfide (MoS 2 )-palladium nanoparticles hybrid structure is used to engineer the oxide/electrode interface of hafnium oxide (HfO x )-based RRAM. Through its interface engineering, the set voltage can be greatly lowered (from -3.5 to -0.8 V) with better uniformity under a relatively thick HfO x layer (≈15 nm), and a 30 times improvement of the memory window can be obtained. Moreover, due to the atomic thickness of MoS 2 film and high transmittance of ITO, the proposed RRAM exhibits high transparency in visible light. As the proposed interface-engineering RRAM exhibits good transparency, low SET voltage, and a large resistive switching window, it has huge potential in data storage in transparent circuits and wearable electronics with relatively low supply voltage. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An MF/HF radio array for radio and radar imaging of the ionosphere

NASA Astrophysics Data System (ADS)

Isham, Brett; Gustavsson, Bjorn; Belyey, Vasyl; Bullett, Terrence

2016-07-01

The Aguadilla Radio Array will be installed at the Interamerican University Aguadilla Campus, located in northwestern Puerto Rico. The array is intended for broad-band medium and high-frequency (MF/HF, roughly 2 to 25 MHz) radio and bistatic radar observations of the ionosphere. The main array consists of 20 antenna elements, arranged in a semi-random pattern providing a good distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. A relocatable 6-element array is also being developed, in which each element consists of a crossed pair of active electric dipoles and all associated electronics for phase-coherent radio measurements. A primary scientific goal of the array is to create images of the region of ionospheric radio emissions stimulated by the new Arecibo Observatory high-power high-frequency radio transmitter. A second primary goal is the study of ionospheric structure and dynamics via coherent radar imaging of the ionosphere in collaboration with the University of Colorado / NOAA Versatile Interferometric Pulsed Ionospheric Radar (VIPIR), located at the USGS San Juan Observatory in Cayey, Puerto Rico. In addition to ionospheric research in collaboration with the Cayey and Arecibo Observatories, the goals of the project include the development of radio sounding, polarization, interferometry, and imaging techniques, and training of students at the university and high school levels.

Report on the HAARP 2008 Winter Campaign Focusing on Artificial Ionospheric Irregularities

DTIC Science & Technology

2008-07-31

Figure Bl. Magnetic field variations recorded by the fluxgate magnetometer 30 Figure B2. Composite ionogram showing the variation of the reflection...variation was monitored by the Fluxgate Magnetometer . The density irregularities were monitored by the Ionosonde. 20:00 Preliminary Results The...magnetic field variations in three directions (H, D, and Z) recorded by the fluxgate magnetometer from UTC 20:00 to 04:00 are shown in the plots of

Applications of the IRI in Southern Africa

NASA Astrophysics Data System (ADS)

Coetzee, P. J.

2004-01-01

The IRI forms the basis of the Single Site Location Direction Finding networks of the South African Defence Force as well as theNational Intelligence Agency. It is also used in "Path Analysis" applications where the possible transmitter coverage is calculated. Another application of the IRI is in HF frequency predictions, especially for the South African Defence Force involved in peace keeping duties in Africa. The IRI is either used independently or in conjunction with vertical ionosondes. In the latter case the scaled F2 peak parameters (foF2, hmF2) are used as inputs to the IRI. The IRI thus gets "calibrated" to extend the area covered by the ionosonde(s). The IRI has proved to be a very important tool in South Africa and Africa in the fight against crime, drug trafficking, political instability and maintaining the peace in potentially unstable countries.

Novel Stimulated Electromagnetic Emission Observations with Artificial Airglow Using RF Excitation with HAARP

NASA Astrophysics Data System (ADS)

Briczinski, S. J., Jr.; Bernhardt, P. A.; Siefring, C. L.; Michell, R.; Hampton, D. L.; Watkins, B. J.; Bristow, W. A.

2014-12-01

Neutral hydrogen plays an important role in determining the state of the plasmasphere and its response to forcing from geomagnetic storms. Hydrogen's solar cycle variation is counterintuitive: there is more hydrogen at solar minimum at 300 km that there is at solar maximum. Similarly there is more hydrogen in winter than in summer and hydrogen density maximizes in the morning. In this presentation we describe these variations and consider some possible causes for them.

Visual analysis as a method of interpretation of the results of satellite ionospheric measurements for exploratory problems

NASA Astrophysics Data System (ADS)

Korneva, N. N.; Mogilevskii, M. M.; Nazarov, V. N.

2016-05-01

Traditional methods of time series analysis of satellite ionospheric measurements have some limitations and disadvantages that are mainly associated with the complex nonstationary signal structure. In this paper, the possibility of identifying and studying the temporal characteristics of signals via visual analysis is considered. The proposed approach is illustrated by the example of the visual analysis of wave measurements on the DEMETER microsatellite during its passage over the HAARP facility.

Comparisons of Measurements and Modeling of Solar Eclipse Effects on VLF Transmissions

NASA Astrophysics Data System (ADS)

Eccles, J. V.; Rice, D. D.; Sojka, J. J.; Marshall, R. A.; Drob, D. P.; Decena, J. C.

2017-12-01

The solar eclipse of 2017 August 21 provides an excellent opportunity to examine Very Low Frequency (VLF) radio signal propagation through the path of the solar eclipse between Navy VLF transmitters and several VLF receivers. The VLF transmitters available for this study radio signal propagation study are NLK in Jim Creek, Washington (24.8 kHz, 192 kW, 48.20N, 121.90W), NML in LaMour, North Dakota (25.2 kHz, 500 kW 46.37N, 93.34W), and NAA in Cutler, Maine (24.0 kHz, 1000 kW, 44.65N, 67.29W). These VLF transmitters provide propagation paths to three VLF receivers at Utah State University (41.75N, 111.76W), Bear Lake Observatory (41.95N, 111.39W), Salt Lake City (40.76N, 111.89W) and one receiver in Boulder, Colorado (40.02N, 105.27W). The solar eclipse shadow will cross all propagations paths during the day and will modify the D region electron density within the solar shadow. The week prior to the solar eclipse will be used to generate a diurnal baseline of VLF single strength for each transmitter-receiver pair. These will be compared to the day of the solar eclipse to identify VLF propagation differences through the solar eclipse shawdow. Additionally, the electron density effects of the week prior and of the solar eclipse day will be modeled using the Data-Driven D Region (DDDR) model [Eccles et al., 2005] with a detailed eclipse solar flux mask. The Long-Wave Propagation Code and the HASEL RF ray-tracing code will be used to generate VLF signal strength for each measured propagation path through the days prior and the solar eclipse day. Model-measurement comparisons will be presented and the D region electron density effects of the solar eclipse will be examined. The DDDR is a time-dependent D region model, which makes it very suitable for the solar eclipse effects on the electron density for the altitude range of 36 to 130 km. Eccles J. V., R. D. Hunsucker, D. Rice, J. J. Sojka (2005), Space weather effects on midlatitude HF propagation paths: Observations and a data-driven D region model, Space Weather, 3, S01002, doi:10.1029/2004SW000094.

Procedures for the use of aircraft in wildlife biotelemetry studies

USGS Publications Warehouse

Gilmer, David S.; Cowardin, Lewis M.; Duval, Renee L.; Mechlin, Larry M.; Shaiffer, Charles W.; Kuechle, V.B.

1981-01-01

This is a report on the state of the art methodology and on questions that arise while one is preparing to use aircraft in a biotelemetry study. In general the first step in preparing to mount an antenna on an aircraft is to consult with a certified aircraft mechanic. Aircraft certification is discussed to provide background information concerning the role of the Federal Aviation Administration (FAA) in regulating the use of biotelemetry antennas on aircraft. However, approval of any specific design of antenna mount rests with local FAA authority. Airplane and helicopter antenna attachments are described. Performance of the receiving antenna system is discussed with emphasis on how variables as aircraft type and antenna configuration may influence reception. The side-looking vs. front-looking antenna configuration and the VHF vs. HF frequency band are generally recommended for most aerial tracking studies. Characteristics of receivers, transmitters, and antennas that might influence tracking are discussed. Specific topics such as calibration of receivers and transmitter quality control are considered. Suggestions in preparing for and conducting tracking flights that will improve overall efficiency and safety are presented. Search techniques, including procedures for conducting large and specific area surveys as well as methods to improve and evaluate search efficiency, are discussed. A concluding section considers special topics such as low-level operations and the use of helicopters. Diagrams of antenna mounts, equipment check-off lists, and antenna test procedures are included as appendices.

Ionospheric modification at twice the electron cyclotron frequency.

PubMed

Djuth, F T; Pedersen, T R; Gerken, E A; Bernhardt, P A; Selcher, C A; Bristow, W A; Kosch, M J

2005-04-01

In 2004, a new transmission band was added to the HAARP high-frequency ionospheric modification facility that encompasses the second electron cyclotron harmonic at altitudes between approximately 220 and 330 km. Initial observations indicate that greatly enhanced airglow occurs whenever the transmission frequency approximately matches the second electron cyclotron harmonic at the height of the upper hybrid resonance. This is the reverse of what happens at higher electron cyclotron harmonics. The measured optical emissions confirm the presence of accelerated electrons in the plasma.

Environmental Impact Statement. Volume 1. Proposed High Frequency Active Auroral Research Program

DTIC Science & Technology

1993-07-01

Proposed HAARP Facility and Potential Borrow Areas P-1 & P-2 Cultural Resources Survey Areas, 1988 - 1990 ....... 3-97 3.9-3 Potential Borrow Area A -1...Cultural Resou Survey Areas 1988 ..... 3-99 3.9-4 Potential Borrow Area A -4 Cultural Resource Survey Areas 1988 ...... 3-101 3.9-5 Potential Borrow Area A -5...1987 (5 holes) and 1988 (2 holes) (USACOE, 1987a; 1988 ), and a series of additional borings conducted in 1989 (Moolin and Associates, 1989). These

Investigation of Plasma Phenomena in the Ionosphere Under Natural Conditions and Under Conditions Artificially Perturbed by HAARP

DTIC Science & Technology

2008-08-31

fabricated, the concept was tested , and a number of design defects were discovered, a usual occurrence. The test board was modified with cuts and...jumper wires to correct the defects and continue testing until the design was verified. Based on the testing , new artwork was prepared. Note that...mobile data was roughly similar to the fixed station data. It also revealed a circuit design defect that required further testing at the Bellevue

Environmental Impact Analysis Process. Final Environmental Impact Statement. Part 2. Proposed High Frequency Active Auroral Research Program.

DTIC Science & Technology

1993-07-01

there are any. The recent set of articles in gcience (1) on the effects of Electromagnetic Fields (EDF) states quite clearly and accurately that we...gone into the explanation of how the HAARP will impact the areas most closely related to the study subject, associated electromagnetic fields and...during break-up each year. page 4-90. Exposure to Humans . This first paragraph is terrible. Concerned citizens will be looking here first to learn if

Characterization and diagnostic methods for geomagnetic auroral infrasound waves

NASA Astrophysics Data System (ADS)

Oldham, Justin J.

Infrasonic perturbations resulting from auroral activity have been observed since the 1950's. In the last decade advances in infrasonic microphone sensitivity, high latitude sensor coverage, time series analysis methods and computational efficiency have elucidated new types of auroral infrasound. Persistent periods of infrasonic activity associated with geomagnetic sub-storms have been termed geomagnetic auroral infrasound waves [GAIW]. We consider 63 GAIW events recorded by the Fairbanks, AK infrasonic array I53US ranging from 2003 to 2014 and encompassing a complete solar cycle. We make observations of the acoustic features of these events alongside magnetometer, riometer, and all-sky camera data in an effort to quantify the ionospheric conditions suitable for infrasound generation. We find that, on average, the generation mechanism for GAIW is confined to a region centered about ~60 0 longitude east of the anti-Sun-Earth line and at ~770 North latitude. We note furthermore that in all cases considered wherein imaging riometer data are available, that dynamic regions of heightened ionospheric conductivity periodically cross the overhead zenith. Consistent features in concurrent magnetometer conditions are also noted, with irregular oscillations in the horizontal component of the field ubiquitous in all cases. In an effort to produce ionosphere based infrasound free from the clutter and unknowns typical of geophysical observations, an experiment was undertaken at the High Frequency Active Auroral Research Program [HAARP] facility in 2012. Infrasonic signals appearing to originate from a source region overhead were observed briefly on 9 August 2012. The signals were observed during a period when an electrojet current was presumed to have passed overhead and while the facilities radio transmitter was periodically heating the lower ionosphere. Our results suggest dynamic auroral electrojet currents as primary sources of much of the observed infrasound, with modulation of the electrojets due to energetic particle precipitation, dispersion due to coupling with gravity waves, and reflection and refraction effects in the intervening atmosphere all potential factors in the shaping of the waveforms observed.

Active experiments in the ionosphere and geomagnetic field variations

NASA Astrophysics Data System (ADS)

Sivokon, V. P.; Cherneva, N. V.; Khomutov, S. Y.; Serovetnikov, A. S.

2014-11-01

Variations of ionospheric-magnetospheric relation energy, as one of the possible outer climatology factors, may be traced on the basis of analysis of natural geophysical phenomena such as ionosphere artificial radio radiation and magnetic storms. Experiments on active impact on the ionosphere have been carried out for quite a long time in Russia as well. The most modern heating stand is located in Alaska; it has been used within the HAARP Program. The possibility of this stand to affect geophysical fields, in particular, the geomagnetic field is of interest.

Radio Pumping of Ionospheric Plasma with Orbital Angular Momentum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leyser, T. B.; Norin, L.; McCarrick, M.

2009-02-13

Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

Heater-induced ionization inferred from spectrometric airglow measurements

NASA Astrophysics Data System (ADS)

Hysell, D. L.; Miceli, R. J.; Varney, R. H.; Schlatter, N.; Huba, J. D.

2013-12-01

Spectrographic airglow measurements were made during an ionospheric modification experiment at HAARP on March 12, 2013. Artificial airglow enhancements at 427.8, 557.7, 630.0, 777.4, and 844.6 nm were observed. On the basis of these emissions and using a methodology based on the method of Backus and Gilbert [1968, 1970], we estimate the suprathermal electron population and the subsequent equilibrium electron density profile, including contributions from electron impact ionization. We find that the airglow is consistent with significant induced ionization in view of the spatial intermittency of the airglow.

Radio pumping of ionospheric plasma with orbital angular momentum.

PubMed

Leyser, T B; Norin, L; McCarrick, M; Pedersen, T R; Gustavsson, B

2009-02-13

Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

Stimulated electromagnetic emission and plasma line during pump wave frequency stepping near 4th electron gyroharmonic at HAARP

NASA Astrophysics Data System (ADS)

Grach, Savely; Sergeev, Evgeny; Shindin, Alexey; Mishin, Evgeny; Watkins, Brenton

Concurrent observations of stimulated (secondary) electromagnetic emissions (SEE) and incoherent plasma line (PL) backscatter from the MUIR radar during HF pumping of the ionosphere by the HAARP heating facility (62.4(°) °N, 145.15(°) W, magnetic inclination α = 75.8^circ) with the pump wave (PW) frequency sweeps about the fourth electron gyroharmonic (4f_c) are presented. The PW frequency f0 was changed every 0.2 s in a 1-kHz step, i.e. with the rate of r_{f_0}=5 kHz/s. PW was transmitted at the magnetic zenith (MZ). Prior to sweeping, PW was transmitted continuously (CW) during 2 min at f_0 = 5730 kHz <4f_c to create the “preconditioned” ionosphere with small-scale magnetic field-aligned irregularities. During CW pumping, a typical SEE spectrum for f_0<4f_c, containing the prominent downshifted maxiμm (DM) shifted by Delta f_{DM} = f_{DM}-f_0approx-9 kHz, developed in 5-10 s after PW turn on. The PL echoes were observed during 2-3 s from the range dsim 220 km corresponding to the altitude slightly above PW reflection height. After sim5 s the PL echoes descended to dsim 210-212 km corresponding to the height h = d / (sinalpha) by sim 7 km below the height where f_0 = 4f_c. During frequency sweeps, two upshifted features appeared in the SEE spectrum for f_0> 4f_c, namely BUM_S and BUM_D. The former (stationary broad upshifted maxiμm) peaks at Delta f_{BUMs} approx f0 - nfc (d) + 15-20 kHz and is a typical SEE spectral feature. The latter, the dynamic BUM_D at smaller Delta f, is observed only at high pump powers (ERP=1.7 GW) and corresponds to artificial descending plasma layers created in the F-region ionosphere [1]. In the experiment in question, the BUM_D was present for f_0> f^*, where f^* was 5805-5815 kHz during stepping up and sim 10 kHz less for stepping down, and located 8-10 km below the background F-layer. The miniμm DM which indicated that f_0=4f_c=f_{uh} in the background ionospheric plasma, was sim 5760 kHz. The PL was observed only for f_0< f^* and mainly from altitudes h where f_0 <4f_c. The height h decreased with increasing f_0 in accordance with the altitude dependence 4f_c(h), the difference Delta f_g = f_0 - 4f_c was kept constant during either sweeping up [-(4-8 kHz)] or sweeping down [-(18-22 kHz)]. This corresponds to the difference between the altitude where f_0=4f_c and the PL generation altitude by Delta h sim 1.5-3 km and 7-8 km, respectively. During stepping up, the PL was observed also from the ranges where f_0 > 4f_c. In this case we obtained Delta f_g sim 8-13 kHz corresponding to Delta h sim - 4 km. The PL has never been observed for f_0>f^*$. \\ 1. Sergeev E., Grach S., et al. //Phys. Rev. Lett., 110 (2013), 065002.

Fabrication and Atomic Force Microscopy Characterization of Molecular Composites of Fullerenes in Aerogel Matrix for Optical Limiting

NASA Technical Reports Server (NTRS)

Lu, W. J .; Sunkara, H. B.; Shi, D.; Morgan, S. H.; Penn, B.; Frazier, D.; Collins, W. E.

1998-01-01

An optical limiter is a device which exhibits a decrease in the transmittance in a material with an increase in intensity of light. Sol-gel techniques offer many advantages in the fabrication of materials. These materials possess many desirable properties for nonlinear optical (NLO) device applications which include transparency, high thermal and chemical stabilities, very low refractive index and dielectric constants. C60 shows a higher excited state absorption cross section than the ground state absorption cross section over the complete visible spectrum, and the spectrum of the excited state absorption of C60 has the same general shape as the ground state absorption. This fact suggests that fullerenes are ideal optical limiting materials. Aerogels are fabricated by sol-gel processing. One of the key issues is the dispersion of fullerenes into small and uniform pores of silica aerogel host matrices. The aerogel network was characterized by Raman spectroscopy. Atomic force microscopy is a technique with many advantages to characterize the aerogel materials. The morphology of the cleaved surface for a C60/aerogel sample shows that there are long paralleled shaped stripes with 20-30 nm in width and about 500 nm in length on the cleaved surface. The cleaved surface also was etched by 5% HF solution for one minutes, and it became smoother after HF etching. The main feature in on the surface is the spherical particles with the size of few nanometers, and no aggregated fullerenes appear. The fullerenes are well dispersed in the aerogel matrices.

A Mid-Latitude Skywave Propagation Experiment: Overview and Results

NASA Astrophysics Data System (ADS)

Munton, D. C.; Calfas, R. S.; Gaussiran, T., II; Rainwater, D.; Flesichmann, A. M.; Schofield, J. R.

2016-12-01

We will describe a mid-latitude HF skywave propagation experiment conducted during 19-27 January, 2014. There were two primary goals to the experiment. First, we wanted to build an understanding of the impact that medium scale traveling ionospheric disturbances have on the angles of arrival of the HF signals. The second goal was to provide a diverse data set that could serve as a baseline for propagation model development and evaluation. We structured individual tests during the experiment to increase the knowledge of temporal and spatial length scales of various ionospheric features. The experiment was conducted during both day and night periods and spanned a wide range of ionospheric states. We conducted the experiment at White Sands Missile Range, New Mexico and in the surrounding area. As part of the experiment, we deployed a number of active HF transmitters, and an array of dipole antennas to provide angle of arrival measurements. We also deployed a smaller array of more novel compact electro-magnetic vector sensors (EMVSs). Other instrumentation specific to the remote sensing of the ionosphere included digisondes, GNSS receivers, beacon satellite receivers, and optical instruments. We will provide a complete description of the experiment configuration and the data products.Finally, we will provide a discussion of experimental results, focusing on ionospheric conditions during the angle-of-arrival determinations, and the impact ionospheric disturbances can have on these measurements. We use the angle-of-arrival determinations to estimate TID properties, including velocity and direction.This research is based upon work supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via US Navy Contract N00024-07-D-6200. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ODNI, IARPA, US Navy, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon.

Unprecedentedly Strong and Narrow Electromagnetic Emissions Stimulated by High-Frequency Radio Waves in the Ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norin, L.; Leyser, T. B.; Nordblad, E.

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

PubMed

Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

2009-02-13

Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

Modulation of whistlers

NASA Astrophysics Data System (ADS)

Sivokon', V. P.; Bogdanov, V. V.; Druzhin, G. I.; Cherneva, N. V.; Kubyshkin, A. V.; Sannikov, D. V.; Agranat, I. V.

2014-11-01

Analysis of the experimental data obtained at Paratunka observatory (53.02° N, 158.65° E; L = 2.3) has revealed a nonstandard form of whistlers involving spectral lines that are symmetric with respect to the whistler. We have shown that this form is most likely due to the amplitude modulation of whistlers by electromagnetic pulses with a length of around 1 s and carrier frequency of around 1.1 kHz. We have suggested that these pulses could be emitted by the auroral electrojet modified by heating radiation from the HAARP facility (62.30° N, 145.30° W; L > 4.2).

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

NASA Technical Reports Server (NTRS)

Bernhardt, P. A.; Ballenthin, J. O.; Baumgardner, J. L.; Bhatt, A.; Boyd, I. D.; Burt, J. M.; Caton, R. G.; Coster, A.; Erickson, P. J.; Huba, J. D.;

Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y-(HF) n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator.

PubMed

Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

2017-01-01

Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF) n . The HF molecules were ionized in the form of complex ions associated with the negative core ions Y - produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y - (HF) n (Y=F, O 2 ), where larger clusters with n ≥4 were not detected. The mechanisms for the formation of the HF, F - (HF) n , and O 2 - (HF) n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F - (HF) n ( n =1-3), the energies for the loss of HF from F - (HF) 3 , F - (HF) 2 , and F - (HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy ( E CM ). These E CM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O 2 (HF) n ] - ( n =1-4) was discussed on the basis of the bond lengths of O 2 H-F - (HF) n and O 2 - H-F(HF) n obtained by ab initio calculations. The calculations indicated that [O 2 (HF) 4 ] - separated into O 2 H and F - (HF) 3 .

A Heart Failure Management Program Using Shared Medical Appointments.

PubMed

Carroll, Allison J; Howrey, Hillary L; Payvar, Susan; Deshida-Such, Kristen; Kansal, Mayank; Brar, Charanjit K

2017-04-01

Disease management programs for heart failure (HF) effectively reduce HF-related hospitalization rates and mortality. Shared medical appointments (SMAs) offer a cost-effective delivery method for HF disease management programs. However, few studies have evaluated this cost-effective delivery method of HF disease management among Veterans with acute HF. We hypothesized that Veterans who attended a multidisciplinary HF-SMA clinic promoting HF self-management, compared those who only received individual treatment through the HF specialty clinic, would have better 12-month hospitalization outcomes. We completed a retrospective review of the VA electronic health record for HF-SMA clinic appointments (1/1/2012 to 12/31/2013). The multidisciplinary HF-SMA program comprised 4 weekly sessions covering topics including HF disease, HF medications, diet adherence, physical activity, psychological well-being, and stress management. Patients who attended the HF-SMA clinic ( n =54) were compared to patients who were scheduled for an HF-SMA appointment but never attended and were followed only in the HF clinic ( n =37). Outcomes were 12-month HF-related and all-cause hospitalization rates, days in the hospital, and time to first hospitalization. Of 141 patients scheduled for an HF-SMA clinic appointment, 54 met criteria for the HF-SMA clinic group and 37 were included in the HF clinic group. The groups did not significantly differ on any sociodemographic variables. Furthermore, no significant differences were observed between the HF-SMA group and the HF clinic group on demographics or hospitalization outcomes, p >.05 for all comparisons. Our results did not support our hypothesis that offering multidisciplinary, HF-SMAs promoting HF self-management skills, above and beyond the individual disease management care provided in an HF specialty clinic, would improve hospitalization outcomes among Veterans with acute HF. Limitations of the present study and recommendations for HF self-management programs for Veterans are discussed.

Collision-Induced Dissociation Study of Strong Hydrogen-Bonded Cluster Ions Y−(HF)n (Y=F, O2) Using Atmospheric Pressure Corona Discharge Ionization Mass Spectrometry Combined with a HF Generator

PubMed Central

Sakamoto, Kenya; Sekimoto, Kanako; Takayama, Mitsuo

2017-01-01

Hydrogen fluoride (HF) was produced by a homemade HF generator in order to investigate the properties of strong hydrogen-bonded clusters such as (HF)n. The HF molecules were ionized in the form of complex ions associated with the negative core ions Y− produced by atmospheric pressure corona discharge ionization (APCDI). The use of APCDI in combination with the homemade HF generator led to the formation of negative-ion HF clusters Y−(HF)n (Y=F, O2), where larger clusters with n≥4 were not detected. The mechanisms for the formation of the HF, F−(HF)n, and O2−(HF)n species were discussed from the standpoints of the HF generator and APCDI MS. By performing energy-resolved collision-induced dissociation (CID) experiments on the cluster ions F−(HF)n (n=1–3), the energies for the loss of HF from F−(HF)3, F−(HF)2, and F−(HF) were evaluated to be 1 eV or lower, 1 eV or higher, and 2 eV, respectively, on the basis of their center-of-mass energy (ECM). These ECM values were consistent with the values of 0.995, 1.308, and 2.048 eV, respectively, obtained by ab initio calculations. The stability of [O2(HF)n]− (n=1–4) was discussed on the basis of the bond lengths of O2H–F−(HF)n and O2−H–F(HF)n obtained by ab initio calculations. The calculations indicated that [O2(HF)4]− separated into O2H and F−(HF)3. PMID:28966900

VHF Scintillation in an Artificially Heated Ionosphere

NASA Astrophysics Data System (ADS)

Suszcynsky, D. M.; Layne, J.; Light, M. E.; Pigue, M. J.; Rivera, L.

2017-12-01

As part of an ongoing project to characterize very-high-frequency (VHF) radio wave propagation through structured ionospheres, Los Alamos National Laboratory has been conducting a set of experiments to measure the scintillation effects of VHF transmissions under a variety of ionospheric conditions. Previous work (see 2015 Fall AGU poster by D. Suszcynsky et al.) measured the S4 index and ionospheric coherence bandwidth in the 32 - 44 MHz frequency range under naturally scintillated conditions in the equatorial region at Kwajalein Atoll during three separate campaigns centered on the 2014 and 2015 equinoxes. In this paper, we will present preliminary results from the February and September, 2017 High Altitude Auroral Research Project (HAARP) Experimental Campaigns where we are attempting to make these measurements under more controlled conditions using the HAARP ionospheric heater in a twisted-beam mode. Two types of measurements are made by transmitting VHF signals through the heated ionospheric volume to the Radio Frequency Propagation (RFProp) satellite experiment. The S4 scintillation index is determined by measuring the power fluctuations of a 135-MHz continuous wave signal and the ionospheric coherence bandwidth is simultaneously determined by measuring the delay spread of a frequency-modulated continuous wave (FMCW) signal in the 130 - 140 MHz frequency range. Additionally, a spatial Fourier transform of the CW time series is used to calculate the irregularity spectral density function. Finally, the temporal evolution of the time series is used to characterize spread-Doppler clutter effects arising from preferential ray paths to the satellite due to refraction off of isolated density irregularities. All results are compared to theory and scaled for comparison to the 32 - 44 MHz Kwajalein measurements.

L-Band Ionosphere Scintillations Observed by A GNSS Receiver Array at HAARP

NASA Astrophysics Data System (ADS)

Morton, Y.; Pelgrum, W.; van Graas, F.

2011-12-01

As we enter a new solar maximum period, GNSS receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to gain better understandings of scintillation effects on GNSS signals. During the past decade, many GPS receivers have been deployed around the globe to monitor ionosphere scintillations. Most of these GPS receivers are commercial receivers whose tracking mechanisms are not designed to operate under ionosphere scintillation. When strong scintillations occur, these receivers will either generate erroneous outputs or completely lose lock. Even when the scintillation is mild, the tracking loop outputs are not true representation of the signal parameters due the tracking loop transfer function. High quality, unprocessed GNSS receiver front end raw IF samples collected during ionosphere scintillations are necessary to produce realistic scintillation signal parameter estimations. In this presentation, we will update our effort in establishing a unique GNSS receiver array at HAARP, Alaska to collect GPS and GLONASS satellite signals at various stages of the GNSS receiver processing. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array as well as additional on-site diagnostic instrumentation measurements obtained from two active heating experiment campaigns conducted in 2011 will be presented. Additionally, we will also highlight and contrast the artificial heating experiment results with observations of natural scintillation events captured by our receivers using an automatic event trigger mechanism during the past year. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

Clinical presentation at first heart failure hospitalization does not predict recurrent heart failure admission.

PubMed

Kosztin, Annamaria; Costa, Jason; Moss, Arthur J; Biton, Yitschak; Nagy, Vivien Klaudia; Solomon, Scott D; Geller, Laszlo; McNitt, Scott; Polonsky, Bronislava; Merkely, Bela; Kutyifa, Valentina

2017-11-01

There are limited data on whether clinical presentation at first heart failure (HF) hospitalization predicts recurrent HF events. We aimed to assess predictors of recurrent HF hospitalizations in mild HF patients with an implantable cardioverter defibrillator or cardiac resynchronization therapy with defibrillator. Data on HF hospitalizations were prospectively collected for patients enrolled in MADIT-CRT. Predictors of recurrent HF hospitalization (HF2) after the first HF hospitalization were assessed using Cox proportional hazards regression models including baseline covariates and clinical presentation or management at first HF hospitalization. There were 193 patients with first HF hospitalization, and 156 patients with recurrent HF events. Recurrent HF rate after the first HF hospitalization was 43% at 1 year, 52% at 2 years, and 55% at 2.5 years. Clinical signs and symptoms, medical treatment, or clinical management of HF at first HF admission was not predictive for HF2. Baseline covariates predicting recurrent HF hospitalization included prior HF hospitalization (HR = 1.59, 95% CI: 1.15-2.20, P = 0.005), digitalis therapy (HR = 1.58, 95% CI: 1.13-2.20, P = 0.008), and left ventricular end-diastolic volume >240 mL (HR = 1.62, 95% CI: 1.17-2.25, P = 0.004). Recurrent HF events are frequent following the first HF hospitalization in patients with implanted implantable cardioverter defibrillator or cardiac resynchronization therapy with defibrillator. Neither clinical presentation nor clinical management during first HF admission was predictive of recurrent HF. Prior HF hospitalization, digitalis therapy, and left ventricular end-diastolic volume at enrolment predicted recurrent HF hospitalization, and these covariates could be used as surrogate markers for identifying a high-risk cohort. © 2017 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

Evaluation of the performance of spectacle lens "transmittance meters".

PubMed

Stephens, G L; Pitts, D G

1994-03-01

Inexpensive transmittance meters have recently been developed for measuring of mean ultraviolet (UV) radiant transmittance and luminous transmittance of spectacle lenses. Our purpose was to determine how accurately these meters measured transmittance. The mean UV transmittance and the luminous transmittance of a series of lenses were determined using a spectrophotometer. Transmittance meters were then used to measure the same lenses. In general, the meters overestimated total (mean) UV transmittance. Luminous transmittance was relatively accurately measured by those meters which had this capability. Although the meters do not measure UV transmittance accurately, they are still useful for determining if a lens transmits any UV radiation. The relatively narrow response range of the meters, centered at 360 to 380 nm, is responsible for the measurement error of mean UV transmittance.

Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution

USGS Publications Warehouse

Patchett, P.J.

1983-01-01

The 176Lu-176Hf isotope method and its applications in earth sciences are discussed. Greater fractionation of Lu/Hf than Sm/Nd in planetary magmatic processes makes 176Hf 177Hf a powerful geochemical tracer. In general, proportional variations of 176Hf 177Hf exceed those of 143Nd l44Nd by factors of 1.5-3 in terrestrial and lunar materials. Lu-Hf studies therefore have a major contribution to make in understanding of terrestrial and other planetary evolution through time, and this is the principal importance of Lu-Hf. New data on basalts from oceanic islands show unequivocally that whereas considerable divergences occur in 176Hf 177Hf- 87Sr 86Sr and 143Nd l44Nd- 87Sr 86Sr diagrams, 176Hf 177Hf and 143Nd 144Nd display a single, linear isotopic variation in the suboceanic mantle. These discordant 87Sr 86Sr relationships may allow, with the acquisition of further Hf-Nd-Sr isotopic data, a distinction between processes such as mantle metasomatism, influence of seawater-altered material in the magma source, or recycling of sediments into the mantle. In order to evaluate the Hf-Nd isotopic correlation in terms of mantle fractionation history, there is a need for measurements of Hf distribution coefficients between silicate minerals and liquids, and specifically for a knowledge of Hf behavior in relation to rareearth elements. For studying ancient terrestrial Hf isotopic variations, the best quality Hf isotope data are obtained from granitoid rocks or zircons. New data show that very U-Pb discordant zircons may have upwardly-biased 176Hf 177Hf, but that at least concordant to slightly discordant zircons appear to be reliable carriers of initial 176Hf 177Hf. Until the controls on addition of radiogenic Hf to zircon are understood, combined zircon-whole rock studies are recommended. Lu-Hf has been demonstrated as a viable tool for dating of ancient terrestrial and extraterrestrial samples, but because it offers little advantage over existing methods, is unlikely to find wide application in pure chronological studies. ?? 1983.

A Software Defined Radio Based Airplane Communication Navigation Simulation System

NASA Astrophysics Data System (ADS)

He, L.; Zhong, H. T.; Song, D.

2018-01-01

Radio communication and navigation system plays important role in ensuring the safety of civil airplane in flight. Function and performance should be tested before these systems are installed on-board. Conventionally, a set of transmitter and receiver are needed for each system, thus all the equipment occupy a lot of space and are high cost. In this paper, software defined radio technology is applied to design a common hardware communication and navigation ground simulation system, which can host multiple airplane systems with different operating frequency, such as HF, VHF, VOR, ILS, ADF, etc. We use a broadband analog frontend hardware platform, universal software radio peripheral (USRP), to transmit/receive signal of different frequency band. Software is compiled by LabVIEW on computer, which interfaces with USRP through Ethernet, and is responsible for communication and navigation signal processing and system control. An integrated testing system is established to perform functional test and performance verification of the simulation signal, which demonstrate the feasibility of our design. The system is a low-cost and common hardware platform for multiple airplane systems, which provide helpful reference for integrated avionics design.

Observations of enhanced ion line frequency spectrum during Arecibo ionospheric modification experiment

NASA Technical Reports Server (NTRS)

Hagfors, T.; Zamlutti, C. J.

1974-01-01

The Arecibo 430 MHz incoherent scatter radar (ISR) was used to monitor the effects of modifying the ionosphere by a high power HF transmitter feeding the 305 m reflector antenna. When in the ordinary magnetoionic mode parametric instabilities develop in the ionosphere near the reflection level. Manifestations of these instabilities are the strong enhancement of Langmuir oscillations in the direction of the ISR beam at a wavelength of 35 cm and the simultaneous much weaker enhancement of ion oscillations in that direction. The spectral analysis of the enhanced peak with a height resolution of 2.4 km shows that the ionic mode enhancement most often has a double humped frequency spectrum corresponding to up- and down-going ion acoustic waves. The shape of the frequency spectrum is interpreted in terms of a stable oscillation which is driven by a secondary electrostatic field caused by nonlinear interaction of Langmuir waves within a cone centered on the magnetic field and by the scattering of the pump field on stable Langmuir waves travelling along the direction of the ISR.

Investigation of porosity and heterojunction effects of a mesoporous hematite electrode on photoelectrochemical water splitting.

PubMed

Liu, Jingling; Shahid, Muhammad; Ko, Young-Seon; Kim, Eunchul; Ahn, Tae Kyu; Park, Jong Hyeok; Kwon, Young-Uk

2013-06-28

In this paper, we report the porosity and heterojunction effects of hematite (α-Fe2O3) on the photoelectrochemical (PEC) water splitting properties. The worm-like mesoporous hematite thin films (MHFs) with a pore size of ~9 nm and a wall thickness of ~5 nm were successfully obtained through the self-assembly process. MHFs formed on FTO showed much better PEC properties than those of nonporous hematite thin films (NP-HF) owing to the suppression of charge recombination. The PEC data of MHFs under front and back illumination conditions indicated that the porous structure allows the diffusion of electrolyte deep inside the MHF increasing the number of holes to be utilized in the water oxidation reaction. A heterojunction structure was formed by introducing a thin layer of SnO2 (~15 nm in thickness) between the MHF and FTO for a dramatically enhanced PEC response, which is attributed to the efficient electron transfer. Our spectroscopic and electrochemical data show that the SnO2 layer functions as an efficient electron transmitter, but does not affect the recombination kinetics of MHFs.

New Digisonde for research and monitoring applications

NASA Astrophysics Data System (ADS)

Reinisch, B. W.; Galkin, I. A.; Khmyrov, G. M.; Kozlov, A. V.; Bibl, K.; Lisysyan, I. A.; Cheney, G. P.; Huang, X.; Kitrosser, D. F.; Paznukhov, V. V.; Luo, Y.; Jones, W.; Stelmash, S.; Hamel, R.; Grochmal, J.

2009-02-01

The new Digisonde-4D, while preserving the basic principles of the Digisonde family, introduces important hardware and software changes that implement the latest capabilities of new digital radio frequency (RF) circuitry and embedded computers. The "D" refers to digital transmitters and receivers in which no analog circuitry is used for conversion between the baseband and the RF. In conjunction with the new hardware design, new software solutions offer significantly enhanced measurement flexibility, enhanced signal selectivity, and new types of data, e.g., the complete set of time domain samples of all four antenna signals suitable for independent scientific analysis. With the new method of mitigating in-band RF interference, the ionogram running time can be made as short as a couple of seconds. The h'(f) precision ranging technique with an accuracy of better than 1 km can be used on a routine basis. The 4D model runs the new ARTIST-5 ionogram autoscaling software which reports in real time the required data for assimilation in ionospheric models. The paper highlights technical advances of the new Digisonde for research and monitoring applications.

Reduced SIRT1 expression correlates with enhanced oxidative stress in compensated and decompensated heart failure

PubMed Central

Akkafa, Feridun; Halil Altiparmak, Ibrahim; Erkus, Musluhittin Emre; Aksoy, Nurten; Kaya, Caner; Ozer, Ahmet; Sezen, Hatice; Oztuzcu, Serdar; Koyuncu, Ismail; Umurhan, Berrin

2015-01-01

Sirtuin-1 (SIRT1) is a longevity factor in mammals initiating the cell survival mechanisms, and preventing ischemic injury in heart. In the etiopathogenesis of heart failure (HF), impairment in cardiomyocyte survival is a notable factor. Oxidative stress comprises a critical impact on cardiomyocyte lifespan in HF. The aim of the present study was to investigate SIRT1 expression in patients with compensated (cHF) and decompensated HF (dHF), and its correlation with oxidative stress. SIRT1 expression in peripheral leukocytes was examined using quantitative RT-PCR in 163 HF patients and 84 controls. Serum total oxidant status (TOS) and total antioxidant status (TAS) were measured via colorimetric assays, and oxidative stress index (OSI) was calculated. Lipid parameters were also determined by routine laboratory methods. SIRT1 mRNA expression was significantly downregulated in HF with more robust decrease in dHF (p=0.002, control vs cHF; p<0.001, control vs dHF). Markedly increased oxidative stress defined as elevated TOS, OSI and low TAS levels were detected in HF patients comparing with the controls (TAS; p=0.010, control vs cHF, p=0.045 control vs dHF, TOS; p=0.004 control vs cHF; p<0.001 control vs dHF, OSI; p<0.001 for both comparisons, respectively). With SIRT1 expression levels, TAS, TOS, OSI, and high density lipoprotein levels in cHF and dHF were determined correlated. SIRT1 expression were significantly reduced in both HF subtypes, particularly in dHF. SIRT1 expression was correlated with the oxidant levels and antioxidant capacity. Data suggest that SIRT1 may have a significant contribution in regulation of oxidant/antioxidant balance in HF etiology and compensation status. PMID:26233702

Meteorite zircon constraints on the bulk Lu-Hf isotope composition and early differentiation of the Earth.

PubMed

Iizuka, Tsuyoshi; Yamaguchi, Takao; Hibiya, Yuki; Amelin, Yuri

2015-04-28

Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. The (176)Lu-(176)Hf radioactive decay system has been widely used to constrain the timescales and mechanisms of silicate differentiation on Earth, but the data interpretation requires accurate estimation of Hf isotope evolution of the bulk Earth. Because both Lu and Hf are refractory lithophile elements, the isotope evolution can be potentially extrapolated from the present-day (176)Hf/(177)Hf and (176)Lu/(177)Hf in undifferentiated chondrite meteorites. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess (176)Hf due to the accelerated decay of (176)Lu resulting from photoexcitation to a short-lived isomer. If so, the paradigm of a chondritic Earth would be invalid for the Lu-Hf system. Herein we report the first, to our knowledge, high-precision Lu-Hf isotope analysis of meteorite crystalline zircon, a mineral that is resistant to metamorphism and has low Lu/Hf. We use the meteorite zircon data to define the Solar System initial (176)Hf/(177)Hf (0.279781 ± 0.000018) and further to identify pristine chondrites that contain no excess (176)Hf and accurately represent the Lu-Hf system of the bulk Earth ((176)Hf/(177)Hf = 0.282793 ± 0.000011; (176)Lu/(177)Hf = 0.0338 ± 0.0001). Our results provide firm evidence that the most primitive Hf in terrestrial zircon reflects the development of a chemically enriched silicate reservoir on Earth as far back as 4.5 billion years ago.

Meteorite zircon constraints on the bulk Lu−Hf isotope composition and early differentiation of the Earth

PubMed Central

Iizuka, Tsuyoshi; Yamaguchi, Takao; Hibiya, Yuki; Amelin, Yuri

2015-01-01

Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. The 176Lu−176Hf radioactive decay system has been widely used to constrain the timescales and mechanisms of silicate differentiation on Earth, but the data interpretation requires accurate estimation of Hf isotope evolution of the bulk Earth. Because both Lu and Hf are refractory lithophile elements, the isotope evolution can be potentially extrapolated from the present-day 176Hf/177Hf and 176Lu/177Hf in undifferentiated chondrite meteorites. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess 176Hf due to the accelerated decay of 176Lu resulting from photoexcitation to a short-lived isomer. If so, the paradigm of a chondritic Earth would be invalid for the Lu−Hf system. Herein we report the first, to our knowledge, high-precision Lu−Hf isotope analysis of meteorite crystalline zircon, a mineral that is resistant to metamorphism and has low Lu/Hf. We use the meteorite zircon data to define the Solar System initial 176Hf/177Hf (0.279781 ± 0.000018) and further to identify pristine chondrites that contain no excess 176Hf and accurately represent the Lu−Hf system of the bulk Earth (176Hf/177Hf = 0.282793 ± 0.000011; 176Lu/177Hf = 0.0338 ± 0.0001). Our results provide firm evidence that the most primitive Hf in terrestrial zircon reflects the development of a chemically enriched silicate reservoir on Earth as far back as 4.5 billion years ago. PMID:25870298

Reconciliation of the excess 176Hf conundrum in meteorites: Recent disturbances of the Lu-Hf and Sm-Nd isotope systematics

NASA Astrophysics Data System (ADS)

Bast, Rebecca; Scherer, Erik E.; Sprung, Peter; Mezger, Klaus; Fischer-Gödde, Mario; Taetz, Stephan; Böhnke, Mischa; Schmid-Beurmann, Hinrich; Münker, Carsten; Kleine, Thorsten; Srinivasan, Gopalan

2017-09-01

The long-lived 176Lu-176Hf and 147Sm-143Nd radioisotope systems are commonly used chronometers, but when applied to meteorites, they can reveal disturbances. Specifically, Lu-Hf isochrons commonly yield dates up to ∼300 Myr older than the solar system and varying initial 176Hf/177Hf values. We investigated this problem by attempting to construct mineral and whole rock isochrons for eucrites and angrites. Meteorites from different parent bodies exhibit similar disturbance features suggesting that a common process is responsible. Minerals scatter away from isochron regressions for both meteorite classes, with low-Hf phases such as plagioclase and olivine typically being most displaced above (or left of) reference isochrons. Relatively Hf-rich pyroxene is less disturbed but still to the point of steepening Lu-Hf errorchrons. Using our Lu-Hf and Sm-Nd data, we tested various Hf and Lu redistribution scenarios and found that decoupling of Lu/Hf from 176Hf/177Hf must postdate the accumulation of significant radiogenic 176Hf. Therefore early irradiation or diffusion cannot explain the excess 176Hf. Instead, disturbed meteorite isochrons are more likely caused by terrestrial weathering, contamination, or common laboratory procedures. The partial dissolution of phosphate minerals may predominantly remove rare earth elements including Lu, leaving relatively immobile and radiogenic Hf behind. Robust Lu-Hf (and improved Sm-Nd) meteorite geochronology will require the development of chemical or physical methods for removing unsupported radiogenic Hf and silicate-hosted terrestrial contaminants without disturbing parent-daughter ratios.

Cinnamon improves insulin sensitivity and alters the body composition in an animal model of the metabolic syndrome.

PubMed

Couturier, K; Batandier, C; Awada, M; Hininger-Favier, I; Canini, F; Anderson, R A; Leverve, X; Roussel, A M

2010-09-01

Polyphenols from cinnamon (CN) have been described recently as insulin sensitizers and antioxidants but their effects on the glucose/insulin system in vivo have not been totally investigated. The aim of this study was to determine the effects of CN on insulin resistance and body composition, using an animal model of the metabolic syndrome, the high fat/high fructose (HF/HF) fed rat. Four groups of 22 male Wistar rats were fed for 12 weeks with: (i) (HF/HF) diet to induce insulin resistance, (ii) HF/HF diet containing 20 g cinnamon/kg of diet (HF/HF + CN), (iii) Control diet (C) and (iv) Control diet containing 20 g cinnamon/kg of diet (C + CN). Data from hyperinsulinemic euglycemic clamps showed a significant decrease of the glucose infusion rates in rats fed the HF/HF diet. Addition of cinnamon to the HF/HF diet increased the glucose infusion rates to those of the control rats. The HF/HF diet induced a reduction in pancreas weight which was prevented in HF/HF+CN group (p<0.01). Mesenteric white fat accumulation was observed in HF/HF rats vs. control rats (p<0.01). This deleterious effect was alleviated when cinnamon was added to the diet. In summary, these results suggest that in animals fed a high fat/high fructose diet to induce insulin resistance, CN alters body composition in association with improved insulin sensitivity. 2010 Elsevier Inc. All rights reserved.

Neogene volcanism associated with back-arc basin tectonics at the northern Fossa Magna, NE Japan

NASA Astrophysics Data System (ADS)

Okamura, S.; Inaba, M.; Shinjo, R.; Adachi, Y.

2016-12-01

New isotopic and trace element data presented here imply a temporal change in magma sources and thermal conditions beneath the northern Fossa Magna of NE Japan from the Miocene to the Pliocene. Rocks from more sediment melt-rich Early Miocene volcanoes have less radiogenic 176Hf/177Hf and 143Nd/144Nd, high Zr/Hf, and little or no Hf anomaly (Hf/Hf*; ˜1.0). The mantle wedge in the Early Miocene consisted of enriched mantle source. We propose that during the onset of subduction, influx of hot asthenospheric mantle provided sufficient heat to partially melt newly subducting sediment. Geochemical modeling results suggest breakdown of zircon in the slab surface sediments for the Early Miocene lavas in the northern Fossa Magna region. In the Middle Miocene, the injection of hot and depleted asthenospheric material replaced the mantle beneath the northern Fossa Magna region of NE Japan. This caused the isotopic signature of the rocks to change from enriched to depleted. The Middle Miocene lavas characterized by most radiogenic Hf and Nd isotope ratios, have high Zr/Hf, low Lu/Hf, and little or no Hf anomaly. An appropriate working petrogenetic model is that the Middle Miocene lavas were derived from asthenospheric depleted mantle, slightly ( < 1%) contaminated by slab melt accompanied by full dissolution of zircon. All the Late Miocene and Pliocene samples are characterized by distinctly more radiogenic 176Hf/177Hf and 143Nd/144Nd, and more negative Hf anomalies (greater Hf/Hf* variability; ˜0.3). The Pliocene samples are displaced toward lower Hf/Hf* and Zr/Hf, and higher Lu/Hf relative to the Middle Miocene samples, which requires mixing between depleted mantle and a partial melt of subducted metasediment saturated with trace quantity of zircon.

A Polyphenol-Rich Fraction Obtained from Table Grapes Decreases Adiposity, Insulin Resistance, and Markers of Inflammation and Impacts Gut Microbiota in High-Fat Fed Mice

PubMed Central

Collins, Brian; Hoffman, Jessie; Martinez, Kristina; Grace, Mary; Lila, Mary Ann; Cockrell, Chase; Nadimpalli, Anuradha; Chang, Eugene; Chuang, Chia-Chi; Zhong, Wei; Mackert, Jessica; Shen, Wan; Cooney, Paula; Hopkins, Robin; McIntosh, Michael

2016-01-01

The objective of this study was to determine if consuming an extractable or non-extractable fraction of table grapes reduced the metabolic consequences of consuming a high-fat, American-type diet. Male C57BL/6J mice were fed a low fat (LF) diet, a high fat (HF) diet, or a HF diet containing whole table grape powder (5% w/w), an extractable, polyphenol-rich (HF-EP) fraction, a non-extractable, polyphenol-poor (HF-NEP) fraction, or equal combinations of both fractions (HF-EP+NEP) from grape powder for 16 weeks. Mice fed the HF-EP and HF-EP+NEP diets had lower percentages of body fat and amounts of white adipose tissue (WAT) and improved glucose tolerance compared to the HF-fed controls. Mice fed the HF-EP+NEP diet had lower liver weights and triglyceride (TG) levels compared to the HF-fed controls. Mice fed the HF-EP+NEP diets had higher hepatic mRNA levels of hormone sensitive lipase and adipose TG lipase, and decreased expression of c-reactive protein compared to the HF-fed controls. In epididymal (visceral) WAT, the expression levels of several inflammatory genes were lower in mice fed the HF-EP and HF-EP+NEP diets compared to the HF-fed controls. Mice fed the HF diets had increased myeloperoxidase activity and impaired localization of the tight junction protein zonula occludens-1 in ileal mucosa compared to the HF-EP and HF-NEP diets. Several of these treatment effects were associated with alterations in gut bacterial community structure. Collectively, these data demonstrate that the polyphenol-rich, EP fraction from table grapes attenuated many of the adverse health consequences associated with consuming a HF diet. PMID:27133434

Future Perspectives for Management of Stage A Heart Failure.

PubMed

Tanaka, Hidekazu

2018-05-07

Patients with Stage A heart failure (HF) show no HF symptoms but have related comorbid diseases with a high risk of progressing to HF. Screening for comorbid diseases warrants closer attention because of the growing interest in addressing Stage A HF as the best means of preventing eventual progression to overt HF such as Stages C and D. The identification of individuals of Stage A HF is potentially useful for the implementation of HF-prevention strategies; however, not all Stage A HF patients develop left ventricular (LV) structural heart disease or symptomatic HF, which lead to advanced HF stages. Therefore, Stage A HF requires management with the long-term goal of avoiding HF development; likewise, Stage B HF patients are ideal targets for HF prevention. Although the early detection of subclinical LV dysfunction is, thus, essential for delaying the progression to HF, the assessment of subclinical LV dysfunction can be challenging. Global longitudinal strain (GLS) as assessed by speckle-tracking echocardiography has recently been reported to be a sensitive marker of early subtle LV myocardial abnormalities, helpful for the prediction of the outcomes for various cardiac diseases, and superior to conventional echocardiographic indices. GLS reflects LV longitudinal myocardial systolic function, and can be assessed usually by means of two-dimensional speckle-tracking. This article reviews the importance of the assessment of subclinical LV dysfunction in Stage A HF patients by means of GLS, and its current potential to prevent progression to later stage HF.

SEMICONDUCTOR TECHNOLOGY: Wet etching characteristics of a HfSiON high-k dielectric in HF-based solutions

NASA Astrophysics Data System (ADS)

Yongliang, Li; Qiuxia, Xu

2010-03-01

The wet etching properties of a HfSiON high-k dielectric in HF-based solutions are investigated. HF-based solutions are the most promising wet chemistries for the removal of HfSiON, and etch selectivity of HF-based solutions can be improved by the addition of an acid and/or an alcohol to the HF solution. Due to densification during annealing, the etch rate of HfSiON annealed at 900 °C for 30 s is significantly reduced compared with as-deposited HfSiON in HF-based solutions. After the HfSiON film has been completely removed by HF-based solutions, it is not possible to etch the interfacial layer and the etched surface does not have a hydrophobic nature, since N diffuses to the interface layer or Si substrate formation of Si-N bonds that dissolves very slowly in HF-based solutions. Existing Si-N bonds at the interface between the new high-k dielectric deposit and the Si substrate may degrade the carrier mobility due to Coulomb scattering. In addition, we show that N2 plasma treatment before wet etching is not very effective in increasing the wet etch rate for a thin HfSiON film in our case.

47 CFR 74.461 - Transmitter power.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The authorized...

47 CFR 74.461 - Transmitter power.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false Transmitter power. 74.461 Section 74.461....461 Transmitter power. (a) Transmitter power is the power at the transmitter output terminals and.... For the purpose of this Subpart, the transmitter power is the carrier power. (b) The authorized...

A routine high-precision method for Lu-Hf isotope geochemistry and chronology

USGS Publications Warehouse

Patchett, P.J.; Tatsumoto, M.

1981-01-01

A method for chemical separation of Lu and Hf from rock, meteorite and mineral samples is described, together with a much improved mass spectrometric running technique for Hf. This allows (i) geo- and cosmochronology using the176Lu???176Hf+??- decay scheme, and (ii) geochemical studies of planetary processes in the earth and moon. Chemical yields for the three-stage ion-exchange column procedure average 90% for Hf. Chemical blanks are <0.2 ng for Lu and Hf. From 1 ??g of Hf, a total ion current of 0.5??10-11 Ampere can be maintained for 3-5 h, yielding 0.01-0.03% precision on the ratio176Hf/177Hf. Normalisation to179Hf/177Hf=0.7325 is used. Extensive results for the Johnson Matthey Hf standard JMC 475 are presented, and this sample is urged as an international mass spectrometric standard; suitable aliquots, prepared from a single batch of JMC 475, are available from Denver. Lu-Hf analyses of the standard rocks BCR-1 and JB-1 are given. The potential of the Lu-Hf method in isotope geochemistry is assessed. ?? 1980 Springer-Verlag.

Depression Effects on Hospital Cost of Heart Failure Patients in California: An Analysis by Ethnicity and Gender.

PubMed

Husaini, Baqar A; Taira, Deborah; Norris, Keith; Adhish, S Vivek; Moonis, Majaz; Levine, Robert

2018-01-01

Depression often interferes with self-management and treatment of medical conditions. This may result in serious medical complications and escalated health-care cost. Study distribution of heart failure (HF) cases estimates the prevalence of depression and its effects on HF-related hospital costs by ethnicity and gender. Secondary data files of California Hospital Discharge System for he year 2010 were examined. For patients with a HF diagnosis, details regarding depression, demographics, comorbid conditions, and hospital costs were studied. Age-adjusted HF rates and depression were examined for whites, blacks, Hispanics, and Asians/Pacific Islanders (AP) by comparing HF patients with depression (HF +D ) versus HF without depression (HF ND ). HF cases ( n = 62,685; average age: 73) included nearly an equal number of males and females. HF rates were higher ( P < 0.001) among blacks compared to Hispanics, AP, and whites and higher among males than females. One-fifth of HF patients had depression, higher among females and whites compared to males and other ethnic groups. Further, HF hospital costs for blacks and AP were higher ( P < 0.001) compared to other groups. The cost for HF +D was 22% higher compared to HF ND , across all gender and ethnic groups, largely due to higher comorbidities, more admissions, and longer hospitalization. Depression, ethnicity, and gender are all associated with increased hospital costs of HF patients. The higher HF and HF +D costs among blacks, AP, and males reflect additional burden of comorbidities (hypertension and diabetes). Prospective studies to assess if selective screening and treating depression among HF patients can reduce hospital costs are warranted.

Association Between Rheumatoid Arthritis and Risk of Ischemic and Nonischemic Heart Failure.

PubMed

Mantel, Ängla; Holmqvist, Marie; Andersson, Daniel C; Lund, Lars H; Askling, Johan

2017-03-14

It is unknown whether the increased risk of heart failure (HF) in rheumatoid arthritis (RA) is independent of ischemic heart disease (IHD). This study sought to investigate the relative risk of HF overall and by subtype (ischemic and nonischemic HF) in patients with RA and to assess the impact of RA disease factors. Two contemporary cohorts of RA subjects were identified from Swedish patient and rheumatology registries and matched 1:10 to general population comparator subjects. A first-ever HF diagnosis (classified as ischemic HF or nonischemic HF based on the presence of IHD) was assessed through registry linkages. Relative risks for a history of HF before RA onset were calculated through odds ratios. Relative risks of incident HF in RA were calculated as hazard ratios (HRs). By the time of RA onset, a history of HF was not more common in RA. In the new-onset RA cohort, the overall HRs for subsequent HF (any type), ischemic HF, and nonischemic HF were between 1.22 and 1.27. The risk of nonischemic HF increased rapidly after RA onset, in contrast to the risk of ischemic HF. High disease activity was associated with all HF types but was most pronounced for nonischemic HF. In the cohort of patients with RA of any duration, the HRs were between 1.71 and 1.88 for the different HF subtypes. Patients with RA are at increased risk of HF that cannot be explained by their increased risk of IHD. The increased risk of nonischemic HF occurred early and was associated with RA severity. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

THERMODYNAMIC PROPERTIES OF Zr AND Hf HALIDES (in Rumanian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lungu, S.N.

1962-01-01

The following standard heats of formation were found: ZrCl/sub 3/, 178.6 plus or minus 3.2; ZrCl/sub 2/, 124.3 plus or minus 3; ZrBr/sub 3/, 151 plus or minus 7; Zr Br/sbu 2/, 100 plus or minus 6; ZrI/sub 3/, 103 plus or minus 6; ZrI/sub 2/, 68 plus or minus 4; and HfCl/sub 4/, 239.4 plus or minus 5.5; HfCl/sub 3/, 186.6; HfCl/sub 2/, 130; HfBr/sub 4/, 200; HfBr/sub 3/, 157; HfBr / sub 2/, 108; HfI/sub 4/, 140; HfI/sub 3/, 113; and HfI/sub 2/, 72 kcal/mole. (R.V.J.)

Investigation and Development of Data-Driven D-Region Model for HF Systems Impacts

NASA Technical Reports Server (NTRS)

Eccles, J. V.; Rice, D.; Sojka, J. J.; Hunsucker, R. D.

2002-01-01

Space Environment Corporation (SEC) and RP Consultants (RPC) are to develop and validate a weather-capable D region model for making High Frequency (HF) absorption predictions in support of the HF communications and radar communities. The weather-capable model will assimilate solar and earth space observations from NASA satellites. The model will account for solar-induced impacts on HF absorption, including X-rays, Solar Proton Events (SPE's), and auroral precipitation. The work plan includes: I . Optimize D-region model to quickly obtain ion and electron densities for proper HF absorption calculations. 2. Develop indices-driven modules for D-region ionization sources for low, mid, & high latitudes including X-rays, cosmic rays, auroral precipitation, & solar protons. (Note: solar spectrum & auroral modules already exist). 3. Setup low-cost monitors of existing HF beacons and add one single-frequency beacon. 4. Use PENEX HF-link database with HF monitor data to validate D-region/HF absorption model using climatological ionization drivers. 5. Develop algorithms to assimilate NASA satellite data of solar, interplanetary, and auroral observations into ionization source modules. 6. Use PENEX HF-link & HF-beacon data for skill score comparison of assimilation versus climatological D-region/HF absorption model. Only some satellites are available for the PENEX time period, thus, HF-beacon data is necessary. 7. Use HF beacon monitors to develop HF-link data assimilation algorithms for regional improvement to the D-region/HF absorption model.

Automated calibration of multistatic arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Henderer, Bruce

A method is disclosed for calibrating a multistatic array having a plurality of transmitter and receiver pairs spaced from one another along a predetermined path and relative to a plurality of bin locations, and further being spaced at a fixed distance from a stationary calibration implement. A clock reference pulse may be generated, and each of the transmitters and receivers of each said transmitter/receiver pair turned on at a monotonically increasing time delay interval relative to the clock reference pulse. Ones of the transmitters and receivers may be used such that a previously calibrated transmitter or receiver of a givenmore » one of the transmitter/receiver pairs is paired with a subsequently un-calibrated one of the transmitters or receivers of an immediately subsequently positioned transmitter/receiver pair, to calibrate the transmitter or receiver of the immediately subsequent transmitter/receiver pair.« less

Lu-Hf constraints on the evolution of lunar basalts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujimaki, H.; Tatsumoto, M.

1984-02-15

Very low Ti basalts andd green glass samples from the moon show high Lu/Hf ratios and low Hf concentrations. Low-Ti lunar basalts show high and variable Lu/Hf ratios and higher Hf concentrations, whereas high-Ti lunar basalts show low Lu/Hf ratios and high Hf concentrations. KREEP basalts have constant Lu/Hf ratios and high but variable Hf concentrations. Using the Lu-Hf behavior as a constraint, we propose a model for the mare basalts evolution. This constraint requires extensive crystallization of the primary lunar magma ocean prior to formation of the lunar mare basalt sources and the KREEP basalts. Mare basalts are producedmore » by the melting of the cumulate rocks, and KREEP basalts represent the residual liquid of the magma ocean.« less

Zircon U-Pb geochronology, Sr-Nd-Hf isotopic composition and geological significance of the Late Triassic Baijiazhuang and Lvjing granitic plutons in West Qinling Orogen

NASA Astrophysics Data System (ADS)

Duan, Meng; Niu, Yaoling; Kong, Juanjuan; Sun, Pu; Hu, Yan; Zhang, Yu; Chen, Shuo; Li, Jiyong

2016-09-01

The Qinling Orogen was a consequence of continental collision of the South China Craton with the North China Craton in the Triassic and caused widespread granitoid magmatism. However, the petrogenesis of these granitoids remains controversial. In this paper, we choose the Baijiazhuang (BJZ) and Lvjing (LJ) plutons in the West Qinling Orogen for a combined study of the zircon U-Pb geochronology, whole-rock major and trace element compositions and Sr-Nd-Hf isotopic characteristics. We obtained zircon crystallization ages of 216 Ma and 212 Ma for the BJZ and the LJ plutons, respectively. The granitoid samples from both plutons have high K2O metaluminous to peraluminous compositions. They are enriched in large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depleted in high field-strength elements (HFSEs) with significant negative Eu anomalies. The BJZ samples have initial Sr isotopic ratios of 0.7032 to 0.7078, εNd(t) of - 10.99 to - 8.54 and εHf (t) of - 10.22 to - 6.41. The LJ granitoids have initial Sr isotopic ratios of 0.7070 to 0.7080, εNd(t) of - 5.37 to - 4.58 and εHf(t) of - 3.64 to - 1.78. The enriched isotopic characteristics of the two plutons are consistent with their source being dominated by ancient continental crust. However, two BJZ samples show depleted Sr isotope compositions, which may infer possible involvement of mantle materials. Mantle-derived melt, which formed from partial melting of mantle wedge peridotite facilitated by dehydration of the subducted/subducting Mianlue ocean crust, provide the required heat for the crustal melting while also contributing to the compositions of these granitoids. That is, the two granitic plutons are magmatic responses to the closure of the Mianlue ocean basin and the continental collision between the Yangtze and South Qinling crustal terranes. (143Nd/144Nd)i = (143Nd/144Nd) - (147Sm/144Nd) × (eλt - 1), εNd(t) = [(143Nd/144Nd) / (143Nd/144Nd)CHUR(t) - 1] × 104, (143Nd/144Nd)CHUR(t) = 0.512638-0.1967 × (eλt - 1), TDM = 1/λ × ln{1 + [((143Nd/144Nd) - 0.51315) / ((147Sm/144Nd) - 0.21317)]}, λ Sm-Nd = 6.54 × 10- 12a- 1. (176Hf/177Hf)i = [(176Hf/177Hf) - (176Lu/177Hf) × (eλt - 1), εHf(t) = [(176Hf/177Hf) / (176Hf/177Hf)CHUR(t) - 1] × 104, TDM1 = 1/λ × ln[1 + ((176Hf/177Hf)Sample - (176Hf/177Hf)DM)/((176Lu/177Hf)Sample - (176Lu/177Hf)DM)], TDM2 = TDM1 - (TDM1 - t)((fCC - fSample) / (fCC - fDM)), fLu-Hf = (176Lu/177Hf)Sample / (176Lu/177Hf)CHUR-1, (176Lu/177Hf)CHUR = 0.0332, (176Hf/177Hf)CHUR, 0 = 0.282785, (176Lu/177Hf)DM = 0.0384, (176Hf/177Hf)DM = 0.28325, fCC, fSample, fDM are their own fLu-Hf, λ = 1.867 × 10- 11a- 1.

Effects of renal sympathetic denervation on the atrial electrophysiology in dogs with pacing-induced heart failure.

PubMed

Wang, Xiaozhan; Zhao, Qingyan; Deng, Hongping; Wang, Xule; Guo, Zongwen; Dai, Zixuan; Xiao, Jinping; Wan, Peixing; Huang, Congxin

2014-10-01

Heart failure (HF) and atrial fibrillation (AF) are associated with sympathetic activation. Renal sympathetic denervation (RSD) can suppress AF vulnerability. The impact of RSD on atrial electrophysiology in experimental HF is unclear. Twenty-two beagles were randomized into control, HF, and HF + RSD groups. Control dogs were implanted cardiac pacemakers without pacing. Dogs in the HF group underwent right ventricular pacing for 3 weeks at 240 beats/min to induce HF. The dogs in the HF + RSD group received RSD and underwent the same HF-inducing procedure. The P-wave dispersion was higher in HF dogs than in the control and HF + RSD dogs (19 ± 3.1 ms vs 13 ± 2.3 ms, 15 ± 2.9 ms, P = 0.04). Conduction time within the interatrium was significantly longer in the HF dogs than that in the control and HF + RSD dogs (39 ± 4 ms vs 31 ± 3 ms, 33 ± 4 ms; P = 0.03). Window of vulnerability (WOV) of AF was widened in the HF dogs than in the HF + RSD dogs (37 ± 5 ms vs 14 ± 3 ms; P < 0.01), while AF could not be induced (WOV = 0) in the control dogs during S1 S2 stimulation. The voltage in the threshold for AF inducibility was lower during ganglionated plexi stimulation in the HF dogs than in the control and HF + RSD dogs (1.8 ± 0.6 V vs 2.5 ± 0.6 V, 2.4 ± 0.4 V; P = 0.04). RSD could reverse the atrial electrical remodeling and decrease AF inducibility in dogs with pacing-induced HF. ©2014 Wiley Periodicals, Inc.

Hf layer thickness dependence of resistive switching characteristics of Ti/Hf/HfO2/Au resistive random access memory device

NASA Astrophysics Data System (ADS)

Nakajima, Ryo; Azuma, Atsushi; Yoshida, Hayato; Shimizu, Tomohiro; Ito, Takeshi; Shingubara, Shoso

2018-06-01

Resistive random access memory (ReRAM) devices with a HfO2 dielectric layer have been studied extensively owing to the good reproducibility of their SET/RESET switching properties. Furthermore, it was reported that a thin Hf layer next to a HfO2 layer stabilized switching properties because of the oxygen scavenging effect. In this work, we studied the Hf thickness dependence of the resistance switching characteristics of a Ti/Hf/HfO2/Au ReRAM device. It is found that the optimum Hf thickness is approximately 10 nm to obtain good reproducibility of SET/RESET voltages with a small RESET current. However, when the Hf thickness was very small (∼2 nm), the device failed after the first RESET process owing to the very large RESET current. In the case of a very thick Hf layer (∼20 nm), RESET did not occur owing to the formation of a leaky dielectric layer. We observed the occurrence of multiple resistance states in the RESET process of the device with a Hf thickness of 10 nm by increasing the RESET voltage stepwise.

A review of treatment strategies for hydrofluoric acid burns: current status and future prospects.

PubMed

Wang, Xingang; Zhang, Yuanhai; Ni, Liangfang; You, Chuangang; Ye, Chunjiang; Jiang, Ruiming; Liu, Liping; Liu, Jia; Han, Chunmao

2014-12-01

Hydrofluoric acid (HF), a dangerous inorganic acid, can cause severe corrosive effects and systemic toxicity. HF enters the human body via where it contacts, such as skin and mucosa, alimentary and respiratory tracts, and ocular surfaces. In the recent years, the incidence of HF burn has tended to increase over time. The injury mechanism of HF is associated primarily with the massive absorption of HF and the release of hydrogen ions. Correct diagnosis and timely treatment are especially important for HF burns. The critical procedure to treat HF burn is to prevent on-going HF absorption, and block the progressive destruction caused by fluoride ions. Due to the distinct characteristics of HF burns, the topical treatment, as well as systemic support, has been emphasised. Whereas, management of patients with HF burns remains a great challenge in some situations. To date, there has been no widely accepted protocol for the rescue of HF burns, partly due to the diversity of HF burns. This paper overviews the current status and problems of treatment strategies for HF burns, for the purpose of promoting the future researches and improvement. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Resveratrol Prevents the Development of Hypertension Programmed by Maternal Plus Post-Weaning High-Fructose Consumption Through Modulation of Oxidative Stress, Nutrient-Sensing Signals, and Gut Microbiota.

PubMed

Tain, You-Lin; Lee, Wei-Chia; Wu, Kay L H; Leu, Steve; Chan, Julie Y H

2018-04-30

High-fructose (HF) intake, oxidative stress, nutrient-sensing signals, and gut microbiota dysbiosis are closely related to the development of hypertension. We investigated whether resveratrol can prevent hypertension induced by maternal plus post-weaning HF diets in adult offspring via the above-mentioned mechanisms. Female Sprague-Dawley rats received either a normal (ND) or 60% high-fructose (HF) diet during gestation and lactation. Male offspring were assigned to five groups (maternal diet/post-weaning diet; n = 8/group): ND/ND, ND/HF, HF/ND, HF/HF, and HF/HF+ Resveratrol. Resveratrol (50 mg/L) was administered in drinking water from weaning to three months of age. We found that HF/HF induced hypertension in adult offspring. Maternal HF diet altered gut microbiota composition in adult offspring, including decreasing the abundance of genera Bacteroides, Dysgonomonas, and Turicibacter, while increasing phylum Verrucomicrobia and Akkermansia muciniphila. Additionally, HF/HF diets increased oxidative stress and decreased renal mRNA expression of Prkaa2, Prkag2, Ppara, Pparb, Ppargc1a, and Sirt4. Resveratrol reduced renal oxidative stress, activated nutrient-sensing signals, modulated gut microbiota, and prevented associated HF/HF-induced programmed hypertension. Targeting oxidative stress, nutrient-sensing signals, and gut microbiota by resveratrol might be a useful therapeutic strategy for treatment of hypertension induced by excessive consumption of fructose in the adult rat offspring. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Maternal obesity and high-fat diet program offspring metabolic syndrome.

PubMed

Desai, Mina; Jellyman, Juanita K; Han, Guang; Beall, Marie; Lane, Robert H; Ross, Michael G

2014-09-01

We determined the potential programming effects of maternal obesity and high-fat (HF) diet during pregnancy and/or lactation on offspring metabolic syndrome. A rat model of maternal obesity was created using an HF diet prior to and throughout pregnancy and lactation. At birth, pups were cross-fostered, thereby generating 4 paradigms of maternal diets during pregnancy/lactation: (1) control (Con) diet during pregnancy and lactation (Con/Con), (2) HF during pregnancy and lactation (HF/HF), (3) HF during pregnancy alone (HF/Con), and (4) HF during lactation alone (Con/HF). Maternal phenotype during pregnancy and the end of lactation evidenced markedly elevated body fat and plasma corticosterone levels in HF dams. In the offspring, the maternal HF diet during pregnancy alone programmed increased offspring adiposity, although with normal body weight, whereas the maternal HF diet during lactation increased both body weight and adiposity. Metabolic disturbances, particularly that of hyperglycemia, were apparent in all groups exposed to the maternal HF diet (during pregnancy and/or lactation), although differences were apparent in the manifestation of insulin resistant vs insulin-deficient phenotypes. Elevated systolic blood pressure was manifest in all groups, implying that exposure to an obese/HF environment is disadvantageous for offspring health, regardless of pregnancy or lactation periods. Nonetheless, the underlying mechanism may differ because offspring that experienced in utero HF exposure had increased corticosterone levels. Maternal obesity/HF diet has a marked impact on offspring body composition and the risk of metabolic syndrome was dependent on the period of exposure during pregnancy and/or lactation. Copyright © 2014 Mosby, Inc. All rights reserved.

Secure ADS-B authentication system and method

NASA Technical Reports Server (NTRS)

Viggiano, Marc J (Inventor); Valovage, Edward M (Inventor); Samuelson, Kenneth B (Inventor); Hall, Dana L (Inventor)

2010-01-01

A secure system for authenticating the identity of ADS-B systems, including: an authenticator, including a unique id generator and a transmitter transmitting the unique id to one or more ADS-B transmitters; one or more ADS-B transmitters, including a receiver receiving the unique id, one or more secure processing stages merging the unique id with the ADS-B transmitter's identification, data and secret key and generating a secure code identification and a transmitter transmitting a response containing the secure code and ADSB transmitter's data to the authenticator; the authenticator including means for independently determining each ADS-B transmitter's secret key, a receiver receiving each ADS-B transmitter's response, one or more secure processing stages merging the unique id, ADS-B transmitter's identification and data and generating a secure code, and comparison processing comparing the authenticator-generated secure code and the ADS-B transmitter-generated secure code and providing an authentication signal based on the comparison result.

Synthesis of Hf 8O 7, a new binary hafnium oxide, at high pressures and high temperatures

DOE PAGES

Bayarjargal, L.; Morgenroth, W.; Schrodt, N.; ...

2017-01-23

In this paper, two binary phases in the system Hf-O have been synthesized at pressures between 12 and 34 GPa and at temperatures up to 3000 K by reacting Hf with HfO 2 using a laser-heated diamond anvil cell. In situ X-ray diffraction in conjunction with density functional theory calculations has been employed to characterize a previously unreported tetragonal Hf 8O 7 phase. This phase has a structure which is based on an fcc Hf packing with oxygen atoms occupying octahedral interstitial positions. Its predicted bulk modulus is 223(1) GPa. The second phase has a composition close to Hf 6O,more » where oxygen atoms occupy octahedral interstitial sites in an hcp Hf packing. Its experimentally determined bulk modulus is 128(30) GPa. Finally, the phase diagram of Hf metal was further constrained at high pressures and temperatures, where we show that α-Hf transforms to β-Hf around 2160(150) K and 18.2 GPa and β-Hf remains stable up to at least 2800 K at this pressure.« less

Tracking magmatic processes through Zr/Hf ratios in rocks and Hf and Ti zoning in zircons: An example from the Spirit Mountain batholith, Nevada

USGS Publications Warehouse

Lowery, Claiborne L.E.; Miller, C.F.; Walker, B.A.; Wooden, J.L.; Mazdab, F.K.; Bea, F.

2006-01-01

Zirconium and Hf are nearly identical geochemically, and therefore most of the crust maintains near-chondritic Zr/Hf ratios of ???35-40. By contrast, many high-silica rhyolites and granites have anomalously low Zr/Hf (15-30). As zircon is the primary reservoir for both Zr and Hf and preferentially incorporates Zr, crystallization of zircon controls Zr/ Hf, imprinting low Zr/Hf on coexisting melt. Thus, low Zr/Hf is a unique fingerprint of effective magmatic fractionation in the crust. Age and compositional zonation in zircons themselves provide a record of the thermal and compositional histories of magmatic systems. High Hf (low Zr/ Hf) in zircon zones demonstrates growth from fractionated melt, and Ti provides an estimate of temperature of crystallization (TTiZ) (Watson and Harrison, 2005). Whole-rock Zr/Hf and zircon zonation in the Spirit Mountain batholith, Nevada, document repeated fractionation and thermal fluctuations. Ratios of Zr/Hf are ???30-40 for cumulates and 18-30 for high-SiO2 granites. In zircons, Hf (and U) are inversely correlated with Ti, and concentrations indicate large fluctuations in melt composition and TTiZ (>100??C) for individual zircons. Such variations are consistent with field relations and ion-probe zircon geochronology that indicate a >1 million year history of repeated replenishment, fractionation, and extraction of melt from crystal mush to form the low Zr/Hf high-SiO2 zone. ?? 2006 The Mineralogical Society.

Heart failure in a cohort of patients with chronic kidney disease: the GCKD study.

PubMed

Beck, Hanna; Titze, Stephanie I; Hübner, Silvia; Busch, Martin; Schlieper, Georg; Schultheiss, Ulla T; Wanner, Christoph; Kronenberg, Florian; Krane, Vera; Eckardt, Kai-Uwe; Köttgen, Anna

2015-01-01

Chronic kidney disease (CKD) is a risk factor for development and progression of heart failure (HF). CKD and HF share common risk factors, but few data exist on the prevalence, signs and symptoms as well as correlates of HF in populations with CKD of moderate severity. We therefore aimed to examine the prevalence and correlates of HF in the German Chronic Kidney Disease (GCKD) study, a large observational prospective study. We analyzed data from 5,015 GCKD patients aged 18-74 years with an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73m² or with an eGFR ≥60 and overt proteinuria (>500 mg/d). We evaluated a definition of HF based on the Gothenburg score, a clinical HF score used in epidemiological studies (Gothenburg HF), and self-reported HF. Factors associated with HF were identified using multivariable adjusted logistic regression. The prevalence of Gothenburg HF was 43% (ranging from 24% in those with eGFR >90 to 59% in those with eGFR<30 ml/min/1.73m2). The corresponding estimate for self-reported HF was 18% (range 5%-24%). Lower eGFR was significantly and independently associated with the Gothenburg definition of HF (p-trend <0.001). Additional significantly associated correlates included older age, female gender, higher BMI, hypertension, diabetes mellitus, valvular heart disease, anemia, sleep apnea, and lower educational status. The burden of self-reported and Gothenburg HF among patients with CKD is high. The proportion of patients who meet the criteria for Gothenburg HF in a European cohort of patients with moderate CKD is more than twice as high as the prevalence of self-reported HF. However, because of the shared signs, symptoms and medications of HF and CKD, the Gothenburg score cannot be used to reliably define HF in CKD patients. Our results emphasize the need for early screening for HF in patients with CKD.

Biological Therapies: Effects of Proinflammatory Pathways and their Inhibition on the Myocardium of Rheumatoid Athritis Patients.

PubMed

Obermair, Florian; Pieringer, Herwig

2015-01-01

The elevated risk of heart failure (HF) in rheumatoid arthritis (RA) is considered to be partly caused by the chronic low-grade systemic inflammation. As potent suppressors of inflammation, biologics were expected to influence HF development in RA. Unfortunately, case reports of HF in RA patients and non-RA HF studies have suggested that these drugs may even increase HF rates in RA. With this review we want to provide insight into the molecular mechanisms by which elevated cytokines, immune cell alterations and biologics influence myocardial function in RA patients. Beside preclinical data, clinical studies that assess the influence of biologics on HF development are reviewed. Preclinical studies suggest a bidirectional role of the investigated cytokines (TNF-alpha, IL- 1, IL-6) on myocardial function. Common mechanisms of immune cell alterations in HF and RA have been observed in preclinical studies. High doses of infliximab in non-RA patients with HF were found to be harmful. The vast majority of retrospective studies suggest that TNF-alpha inhibitors do not increase the risk of HF development in RA patients. Nevertheless randomized controlled trials are missing and TNF-alpha inhibitors are contraindicated in RA patients with HF NYHA III/IV and should be used with caution in RA patients with HF NYHA I/II based on non-RA HF studies. Due to rare adverse events of HF, rituximab is contraindicated in RA patients with HF NYHA IV. Cytokines seem to have a bidirectional influence on HF development in RA. According to the published evidence it is unlikely that TNFalpha inhibitors substantially increase the risk of HF development in an RA population. Nevertheless they are contraindicated in RA patients with HF NYHA III/IV and should be used with caution in RA patients with HF NYHA I/II. The influence of anakinra, tocilizumab, rituximab and abatacept needs to be investigated in future studies.

Characteristics of high-k gate dielectric formed by the oxidation of sputtered Hf/Zr/Hf thin films on the Si substrate

NASA Astrophysics Data System (ADS)

Kim, H. D.; Roh, Y.; Lee, J. E.; Kang, H.-B.; Yang, C.-W.; Lee, N.-E.

2004-07-01

We have investigated the effects of high temperature annealing on the physical and electrical properties of multilayered high-k gate oxide [HfSixOy/HfO2/intermixed-layer(IL)/ZrO2/intermixed-layer(IL)/HfO2] in metal-oxide-semiconductor device. The multilayered high-k films were formed after oxidizing the Hf/Zr/Hf films deposited directly on the Si substrate. The subsequent N2 annealing at high temperature (>= 700 °C) not only results in the polycrystallization of the multilayered high-k films, but also causes the diffusion of Zr. The latter transforms the HfSixOy/HfO2/IL/ZrO2/IL/HfO2 film into the Zr-doped HfO2 film, and improves electrical properties in general. However, the thin SiOx interfacial layer starts to form if annealing temperature increases over 700 °C, deteriorating the equivalent oxide thickness. .

Influence of the Helicopter Time Domain Electromagnetic System Off-Time Response by the Transmitter Assembly

NASA Astrophysics Data System (ADS)

Vetrov, A.; Mejzr, I.

2010-12-01

While developing a new Helicopter Time Domain Electromagnetic system (P-THEM), Pico Envirotec Inc (PEI) has studied the effect of the transmitter assembly on the acquired data. The P-THEM system consists of a loop-transmitter assembly, powered by a motor generator, 3-axis coil receiver attached at the midpoint of a tow cable and an additional Z-axis (dB/dt) receiver installed on the rear section of the transmitter loop. The system is towed by a helicopter on a 230 foot long tow cable. The transmitter loop is designed to produce a peak magnetic moment of approximately 250,000 NIA with a base frequency of 30 Hz (adjustable to 25Hz) and a quarter length duty cycle (4 ms on-time). The secondary field acquired with a dB/dt receiver coil consists of a ground response and a system response: SF=Rg+Rsys, where SF - the secondary field, Rg - ground response, Rsys - system response. The system itself, especially the transmitter assembly, being a conductor in an induced magnetic field, creates a magnetic anomaly. The influence of the transmitter assembly anomaly on the received signal depends on the position of the receiver coil against the transmitter, the intensity of on-time pulse and transmitter electro-magnetic properties. At the same time, the ground response acquired with a receiver coil depends on the length and the moment of transmitter pulse, as well as the position and distance of the receiver coil from the ground. This can be for vertical field (Z) receiver coil described as RXz(t)=e(t)pz(t)Rgz(t)+d(t)k(t)j(t)TXz(t), where RXz(t) - receiver response, e(t) - elevation of the receiver over the ground, pz(t) - horizontal projection of the receiver coil, Rgz(t) - vertical component of ground response, d(t) - distance (elevation) between the receiver coil and the transmitter loop, k(t) - the position of the receiver in the transmitter field, j(t) - the transmitter assembly electromagnetic properties, TXz(t) -transmitter field (Primary field on-time, and transmitter assembly response off-time). Changes in the electromagnetic properties of the transmitter loop and mechanical vibrations of the transmitter and receiver are much lower frequency in comparison with the base frequency and can be omitted from consideration of a one cycle length period. The transmitter assembly response has to be subtracted from acquired off-time decay for a correct interpretation of ground response. The transmitter influence is very low when the receiving coil is placed far away. However, the transmitter influence is very important when the receiver is close to the transmitter assembly due to the transmitter anomaly decay which then becomes greater than the ground response. The transmitter assembly off-time response can be registered when the system is flown at a sufficiently high altitude and it is not affected by ground conductors. A number of experiments were conducted to determine the transmitter influence content in the acquired data. The secondary dB/dt receiver installed at different elevations over the transmitter loop in test flights It showed the influence change of the transmitter assembly on the acquired secondary field (OFF-time) dependent upon the distance between the transmitter assembly and the receiver loop.

Design for human factors (DfHF): a grounded theory for integrating human factors into production design processes.

PubMed

Village, Judy; Searcy, Cory; Salustri, Filipo; Patrick Neumann, W

2015-01-01

The 'design for human factors' grounded theory explains 'how' human factors (HF) went from a reactive, after-injury programme in safety, to being proactively integrated into each step of the production design process. In this longitudinal case study collaboration with engineers and HF Specialists in a large electronics manufacturer, qualitative data (e.g. meetings, interviews, observations and reflections) were analysed using a grounded theory methodology. The central tenet in the theory is that when HF Specialists acclimated to the engineering process, language and tools, and strategically aligned HF to the design and business goals of the organisation, HF became a means to improve business performance. This led to engineers 'pulling' HF Specialists onto their team. HF targets were adopted into engineering tools to communicate HF concerns quantitatively, drive continuous improvement, visibly demonstrate change and lead to benchmarking. Senior management held engineers accountable for HF as a key performance indicator, thus integrating HF into the production design process. Practitioner Summary: Research and practice lack explanations about how HF can be integrated early in design of production systems. This three-year case study and the theory derived demonstrate how ergonomists changed their focus to align with design and business goals to integrate HF into the design process.

47 CFR 22.625 - Transmitter locations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Transmitter locations. 22.625 Section 22.625... Paging and Radiotelephone Service Point-To-Multipoint Operation § 22.625 Transmitter locations. This... channels will occur. (1) Control transmitter locations. Control transmitter locations must be within 80...

A thermodynamic model for the solubility of HfO2(am) in the aqueous K +– HCO 3 -– CO 3 2-–O -–H 2O system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rai, Dhanpat; Kitamura, Akira; Rosso, Kevin M.

Solubility of HfO2(am) was determined as a function of KHCO3 concentrations ranging from 0.001 mol·kg-1 to 0.1 mol·kg-1. The solubility of HfO2(am) increased dramatically with the increase in KHCO3 concentrations, indicating that Hf(IV) makes strong complexes with carbonate. Thermodynamic equilibrium constants for the formation of Hf-carbonate complexes were determined using both the Pitzer and SIT models. The dramatic increase in Hf concentrations with the increase in KHCO3 concentrations can best be described by the formation of Hf(OH-)2(CO3)22- and Hf(CO3)56-. The log10 K0 values for the reactions [Hf4++2CO32-+2OH-⇌Hf(OH)2(CO3)22-] and [Hf4++5CO32-⇌Hf(CO3)56-], based on the SIT model, were determined to be 44.53±0.46 andmore » 41.53±0.46, respectively, and based on the Pitzer model they were 44.56±0.48 and 40.20±0.48, respectively.« less

Psychometric Analysis of the Heart Failure Somatic Perception Scale as a Measure of Patient Symptom Perception.

PubMed

Jurgens, Corrine Y; Lee, Christopher S; Riegel, Barbara

Symptoms are known to predict survival among patients with heart failure (HF), but discrepancies exist between patients' and health providers' perceptions of HF symptom burden. The purpose of this study is to quantify the internal consistency, validity, and prognostic value of patient perception of a broad range of HF symptoms using an HF-specific physical symptom measure, the 18-item HF Somatic Perception Scale v. 3. Factor analysis of the HF Somatic Perception Scale was conducted in a convenience sample of 378 patients with chronic HF. Convergent validity was examined using the Physical Limitation subscale of the Kansas City Cardiomyopathy Questionnaire. Divergent validity was examined using the Self-care of HF Index self-care management score. One-year survival based on HF Somatic Perception Scale scores was quantified using Cox regression controlling for Seattle HF Model scores to account for clinical status, therapeutics, and lab values. The sample was 63% male, 85% white, 67% functionally compromised (New York Heart Association class III-IV) with a mean (SD) age of 63 (12.8) years. Internal consistency of the HF Somatic Perception Scale was α = .90. Convergent (r = -0.54, P < .0001) and divergent (r = 0.18, P > .05) validities were supported. Controlling for Seattle HF scores, HF Somatic Perception Scale was a significant predictor of 1-year survival, with those most symptomatic having worse survival (hazard ratio, 1.012; 95% confidence interval, 1.001-1.024; P = .038). Perception of HF symptom burden as measured by the HF Somatic Perception Scale is a significant predictor of survival, contributing additional prognostic value over and above objective Seattle HF Risk Model scores. This analysis suggests that assessment of a broad range of HF symptoms, or those related to dyspnea or early and subtle symptoms, may be useful in evaluating therapeutic outcomes and predicting event-free survival.

Impact of sacubitril/valsartan on heart failure admissions: insights from real-world patient prescriptions.

PubMed

Martens, Pieter; Lambeets, Seppe; Lau, Chirikwah; Dupont, Matthias; Mullens, Wilfried

2018-06-17

Sacubitril/valsartan reduced heart failure (HF)-admissions and cardiovascular mortality in the PARADIGM-HF-trial. However, real-world patients are often frailer and less able to tolerate high doses of sacubitril/valsartan. We performed a retrospective analysis of consecutive patients prescribed sacubitril/valsartan in a single tertiary HF-clinic between December 2016 and January 2018. HF-admissions were assessed in a paired fashion, comparing the amount of antecedent HF-episodes with incident HF-episodes after the initiation. Baseline risk for adverse events was assessed by the EMPHASIS-HF-risk-score Results: A total of 201-HF-patients were retrospectively identified (age = 68 ± 11 years, ejection fraction = 29 ± 8%). Real world patients were older, had higher serum creatinine and a higher New-York Heart-Association (NYHA)-class (p < .05 for all) than in the PARADIGM-HF trial. Over a mean duration of 221 ± 114 days after initiation of sacubitril/valsartan a total of 23-individual patients experienced at least one HF-episodes. Over the same time period preceding initiation of sacubitril/valsartan, 51 individual patients experienced a HF-episodes (p < .001). Sacubitril/valsartan significantly reduced the rate of incident vs. antecedent HF-admissions, in patients with low or high baseline NYHA-class (II vs. III and IV; p value = 0.019 respectively p = .004) or patients with an EMPHASIS-HF risk score below or above the mean (p = .002 respectively p = .016). Patients older than 75-years exhibited a trend towards HF-reduction. Higher doses of sacubitril/valsartan were associated with more reduction in incident versus antecedent HF-episodes. Despite being frailer and older, real-world patients exhibit a significant and early reduction in incident HF-hospitalisations following initiation of sacubitril/valsartan. Higher doses might be associated with more reduction in HF-admissions, underscoring the importance of dose uptitration.

Evaluation of 2 methods for sodium intake assessment in cardiac patients with and without heart failure: the confounding effect of loop diuretics.

PubMed

Arcand, JoAnne; Floras, John S; Azevedo, Eduardo; Mak, Susanna; Newton, Gary E; Allard, Johane P

2011-03-01

Twenty-four-hour urine collections are considered the optimal method for sodium intake assessment. Whether a diagnosis of heart failure (HF) or the use of loop diuretic (LD) therapy for HF compromises the validity of 24-h urine collections as a surrogate marker for sodium intake is unknown. The objective was to determine the strength of association between 24-h urine collections and food records for sodium intake assessment in non-HF cardiac patients and in HF patients stratified by LD usage. Food records and 24-h urine collections were simultaneously completed for 2 consecutive days. Correlation coefficients and the Bland-Altman method of agreement described the relation between the techniques. Non-HF cardiac patients (n = 96; mean ± SD age: 65 ± 11 y), HF patients who were not taking an LD (n = 47; 62 ± 11 y), and HF patients who were taking an LD (n = 62; age: 60 ± 12 y) were included. Correlation coefficients for sodium intake between food records and urine collections were r = 0.624 (P < 0.001) for non-HF cardiac patients and r = 0.678 (P < 0.001) for HF patients who were not taking an LD. However, no significant association (r = 0.132, P = 0.312) was observed for HF patients who were taking LDs. The 95% limits of agreement between the non-HF cardiac patients and the HF patients who were not taking LDs were similar but were ≈50% wider for HF patients who were taking LDs. For the assessment of sodium intake, food records agree well with 24-h urine collections in non-HF patients with cardiovascular disease and in HF patients who are not receiving LD but not for HF patients who are taking LDs. Therefore, food records may provide a better estimate of sodium intake in HF patients who are receiving LD therapy.

47 CFR 80.959 - Radiotelephone transmitter.

Code of Federal Regulations, 2010 CFR

2010-10-01

... watts into 50 ohms nominal resistance when operated with its rated supply voltage. The transmitter must... capability of the transmitter, measurements of primary supply voltage and transmitter output power must be... voltage measured at the power input terminals to the transmitter terminated in a matching artificial load...

Composition effects on mechanical properties of tungsten-rhenium-hafnium-carbon alloys

NASA Technical Reports Server (NTRS)

Witzke, W. R.

1973-01-01

The mechanical properties of rod and sheet fabricated from arc melted W-4Re-Hf-C alloys containing up to about 0.8 mol percent hafnium carbide (HfC) were evaluated in the as-worked condition. The DBTT's of electropolished bend and tensile specimens were independent of HfC content in this range but dependent on excess Hf or C above that required for stoichiometric HfC. Low temperature ductility was a maximum at Hf contents slightly in excess of stoichiometric. Variations in high temperature strength were also dependent on excess Hf and C. Maximum creep strengthening also occurred at Hf contents in excess of stoichiometric. Analysis of extracted second phase particles indicated that creep strength was reduced by increasing WC content in the HfC particles.

Forecasting the impact of heart failure in the United States: a policy statement from the American Heart Association.

PubMed

Heidenreich, Paul A; Albert, Nancy M; Allen, Larry A; Bluemke, David A; Butler, Javed; Fonarow, Gregg C; Ikonomidis, John S; Khavjou, Olga; Konstam, Marvin A; Maddox, Thomas M; Nichol, Graham; Pham, Michael; Piña, Ileana L; Trogdon, Justin G

2013-05-01

Heart failure (HF) is an important contributor to both the burden and cost of national healthcare expenditures, with more older Americans hospitalized for HF than for any other medical condition. With the aging of the population, the impact of HF is expected to increase substantially. We estimated future costs of HF by adapting a methodology developed by the American Heart Association to project the epidemiology and future costs of HF from 2012 to 2030 without double counting the costs attributed to comorbid conditions. The model assumes that HF prevalence will remain constant by age, sex, and race/ethnicity and that rising costs and technological innovation will continue at the same rate. By 2030, >8 million people in the United States (1 in every 33) will have HF. Between 2012 and 2030, real (2010$) total direct medical costs of HF are projected to increase from $21 billion to $53 billion. Total costs, including indirect costs for HF, are estimated to increase from $31 billion in 2012 to $70 billion in 2030. If one assumes all costs of cardiac care for HF patients are attributable to HF (no cost attribution to comorbid conditions), the 2030 projected cost estimates of treating patients with HF will be 3-fold higher ($160 billion in direct costs). The estimated prevalence and cost of care for HF will increase markedly because of aging of the population. Strategies to prevent HF and improve the efficiency of care are needed.

Dysbiosis and compositional alterations with aging in the gut microbiota of patients with heart failure

PubMed Central

Kamo, Takehiro; Suda, Wataru; Saga-Kamo, Akiko; Shimizu, Yu; Yagi, Hiroki; Liu, Qing; Nomura, Seitaro; Naito, Atsuhiko T.; Takeda, Norifumi; Harada, Mutsuo; Toko, Haruhiro; Kumagai, Hidetoshi; Ikeda, Yuichi; Takimoto, Eiki; Suzuki, Jun-ichi; Honda, Kenya; Morita, Hidetoshi; Hattori, Masahira; Komuro, Issei

2017-01-01

Emerging evidence has suggested a potential impact of gut microbiota on the pathophysiology of heart failure (HF). However, it is still unknown whether HF is associated with dysbiosis in gut microbiota. We investigated the composition of gut microbiota in patients with HF to elucidate whether gut microbial dysbiosis is associated with HF. We performed 16S ribosomal RNA gene sequencing of fecal samples obtained from 12 HF patients and 12 age-matched healthy control (HC) subjects, and analyzed the differences in gut microbiota. We further compared the composition of gut microbiota of 12 HF patients younger than 60 years of age with that of 10 HF patients 60 years of age or older. The composition of gut microbial communities of HF patients was distinct from that of HC subjects in both unweighted and weighted UniFrac analyses. Eubacterium rectale and Dorea longicatena were less abundant in the gut microbiota of HF patients than in that of HC subjects. Compared to younger HF patients, older HF patients had diminished proportions of Bacteroidetes and larger quantities of Proteobacteria. The genus Faecalibacterium was depleted, while Lactobacillus was enriched in the gut microbiota of older HF patients. These results suggest that patients with HF harbor significantly altered gut microbiota, which varies further according to age. New concept of heart-gut axis has a great potential for breakthroughs in the development of novel diagnostic and therapeutic approach for HF. PMID:28328981

Forecasting the Impact of Heart Failure in the United States

PubMed Central

Heidenreich, Paul A.; Albert, Nancy M.; Allen, Larry A.; Bluemke, David A.; Butler, Javed; Fonarow, Gregg C.; Ikonomidis, John S.; Khavjou, Olga; Konstam, Marvin A.; Maddox, Thomas M.; Nichol, Graham; Pham, Michael; Piña, Ileana L.; Trogdon, Justin G.

2013-01-01

Background Heart failure (HF) is an important contributor to both the burden and cost of national healthcare expenditures, with more older Americans hospitalized for HF than for any other medical condition. With the aging of the population, the impact of HF is expected to increase substantially. Methods and Results We estimated future costs of HF by adapting a methodology developed by the American Heart Association to project the epidemiology and future costs of HF from 2012 to 2030 without double counting the costs attributed to comorbid conditions. The model assumes that HF prevalence will remain constant by age, sex, and race/ethnicity and that rising costs and technological innovation will continue at the same rate. By 2030, >8 million people in the United States (1 in every 33) will have HF. Between 2012 and 2030, real (2010$) total direct medical costs of HF are projected to increase from $21 billion to $53 billion. Total costs, including indirect costs for HF, are estimated to increase from $31 billion in 2012 to $70 billion in 2030. If one assumes all costs of cardiac care for HF patients are attributable to HF (no cost attribution to comorbid conditions), the 2030 projected cost estimates of treating patients with HF will be 3-fold higher ($160 billion in direct costs). Conclusions The estimated prevalence and cost of care for HF will increase markedly because of aging of the population. Strategies to prevent HF and improve the efficiency of care are needed. PMID:23616602

Butter naturally enriched in cis-9, trans-11 CLA prevents hyperinsulinemia and increases both serum HDL cholesterol and triacylglycerol levels in rats.

PubMed

de Almeida, Mariana Macedo; Luquetti, Sheila Cristina Potente Dutra; Sabarense, Céphora Maria; do Amaral Corrêa, José Otávio; dos Reis, Larissa Gomes; Santos da Conceição, Ellen Paula; Lisboa, Patrícia Cristina; de Moura, Egberto Gaspar; Gameiro, Jacy; da Gama, Marco Antônio Sundfeld; Lopes, Fernando César Ferraz; Garcia, Raúl Marcel González

2014-12-22

Evidence from in vitro and animal studies indicates that conjugated linoleic acid (CLA) possesses anti-diabetic properties, which appear to be attributed to cis-9, trans-11 CLA, the major CLA isomer in ruminant fat. However, there is a shortage of studies addressing CLA from natural source. The present study aimed to evaluate the effects of butter naturally enriched in cis-9, trans-11 CLA on parameters related to glucose tolerance, insulin sensitivity and dyslipidemia in rats. Forty male Wistar rats were randomly assigned to the following dietary treatments (n=10/group), for 60 days: 1) Normal fat-Soybean oil (NF-So): diet containing 4.0% soybean oil (SO); 2) High Fat-Control Butter (HF-Cb): diet containing 21.7% control butter and 2.3% SO; 3) High Fat-CLA enriched Butter (HF-CLAb): diet containing 21.7% cis-9, trans-11 CLA-enriched butter and 2.3% SO; and 4) High fat-Soybean oil (HF-So): diet containing 24.0% SO. HF-Cb and HF-CLAb diets contained 0.075% and 0.235% of cis-9, trans-11 CLA, respectively. HF-CLAb-fed rats had lower serum insulin levels at fasting than those fed with the HF-Cb diet, while the PPARγ protein levels in adipose tissue was increased in HF-CLAb-fed rats compared to HF-Cb-fed rats. Furthermore, R-QUICK was lower in HF-Cb than in NF-So group, while no differences in R-QUICK were observed among NF-So, HF-CLAb and HF-So groups. Serum HDL cholesterol levels were higher in HF-CLAb-fed rats than in those fed NF-So, HF-Cb and HF-So diets, as well as higher in NF-So-fed rats than in HF-Cb and HF-So-fed rats. HF-CLAb, HF-Cb and HF-So diets reduced serum LDL cholesterol levels when compared to NF-So, whereas serum triacylglycerol levels were increased in HF-CLAb. Feeding rats on a high-fat diet containing butter naturally enriched in cis-9, trans-11 CLA prevented hyperinsulinemia and increased HDL cholesterol, which could be associated with higher levels of cis-9, trans-11 CLA, vaccenic acid, oleic acid and lower levels of short and medium-chain saturated fatty acids from butter naturally modified compared to control butter. On the other hand CLA-enriched butter also increased serum triacylglycerol levels, which could be associated with concomitant increases in the content of trans-9 and trans-10 C18:1 isomers in the CLA-enriched butter.

Oscillating two-stream instability in a magnetized electron-positron-ion plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tinakiche, Nouara; Faculty of Physics, U.S.T.H.B, Algiers 16111; Annou, R.

2015-04-15

Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed usingmore » the Arecibo and HAARP parameters.« less

Oscillating two-stream instability in a magnetized electron-positron-ion plasma

NASA Astrophysics Data System (ADS)

Tinakiche, Nouara; Annou, R.

2015-04-01

Oscillating two-stream instability (OTSI) in a magnetized electron-ion plasma has been thoroughly studied, e.g., in ionospheric heating experiments [C. S. Liu and V. K. Tripathi, Interaction of Electromagnetic Waves With Electron Beams and Plasmas (World Scientific, 1994); V. K. Tripathi and P. V. Siva Rama Prasad, J. Plasma Phys. 41, 13 (1989); K. Ramachandran and V. K. Tripathi, IEEE Trans. Plasma Sci. 25, 423 (1997)]. In this paper, OTSI is investigated in a magnetized electron-positron-ion plasma. The dispersion relation of the process is established. The pump field threshold, along with the maximum growth rate of the instability is assessed using the Arecibo and HAARP parameters.

The Development and Acceptability of a Mobile Application for Tracking Symptoms of Heart Failure Among Older Adults.

PubMed

Portz, Jennifer Dickman; Vehovec, Anton; Dolansky, Mary A; Levin, Jennifer B; Bull, Sheana; Boxer, Rebecca

2018-02-01

Heart failure (HF) is common in older adults. With increases in technology use among older adults, mobile applications may provide a solution for older adults to self-manage symptoms of HF. This article discusses the development and acceptability of a HF symptom-tracking mobile application (HF app). The HF app was developed to allow patients to track their symptoms of HF. Thirty (N = 30) older adults completed an acceptability survey after using the mobile app. The survey used Likert items and open-ended feedback questions. Overall, the acceptability feedback from users was positive with participants indicating that the HF app was both easy to use and understand. Participants identified recommendations for improvement including additional symptoms to track and the inclusion of instructions and reminders. HF is common in older adults, and acceptability of mobile apps is of key importance. The HF app is an acceptable tool for older patients with HF to self-manage their symptoms, identify patterns, and changes in symptoms, and ultimately prevent HF readmission.

Proposed truncated Cu-Hf tight-binding potential to study the crystal-to-amorphous phase transition

NASA Astrophysics Data System (ADS)

Cui, Yuanyuan; Li, Jiahao; Dai, Ye; Liu, Baixin

2010-09-01

Proposed truncated Cu-Hf tight-binding potential was constructed by fitting the physical properties of Cu, Hf, and their stable compounds, i.e., Cu5Hf, Cu8Hf3, Cu10Hf7, and CuHf2. Based on the constructed potentials, molecular dynamics simulations were carried out to compare the relative stability of the crystalline solid solution and the disordered state. Simulation results not only reveal that the physical origin of crystal-to-amorphous transition is the crystalline lattice collapsing when the solute atoms exceeding the critical concentration, but also predict that the glass forming range (GFR) of the Cu-Hf system is 21-77 at. % Cu, which covers the GFRs determined by various metallic glass-producing techniques. Ion beam mixing experiments of the Cu-Hf system were conducted using 200 keV xenon ions and the results show that a uniform amorphous phase can be obtained in the Cu23Hf77 sample, matching well with the GFR determined by the interatomic potential, which, in turn, provides additional evidence to the relevance of the constructed Cu-Hf potential.

ANMCO/SIC Consensus Document: cardiology networks for outpatient heart failure care

PubMed Central

Gulizia, Michele Massimo; Di Lenarda, Andrea; Mortara, Andrea; Battistoni, Ilaria; De Maria, Renata; Gabriele, Michele; Iacoviello, Massimo; Navazio, Alessandro; Pini, Daniela; Di Tano, Giuseppe; Marini, Marco; Ricci, Renato Pietro; Alunni, Gianfranco; Radini, Donatella; Metra, Marco; Romeo, Francesco

2017-01-01

Abstract Changing demographics and an increasing burden of multiple chronic comorbidities in Western countries dictate refocusing of heart failure (HF) services from acute in-hospital care to better support the long inter-critical out-of- hospital phases of HF. In Italy, as well as in other countries, needs of the HF population are not adequately addressed by current HF outpatient services, as documented by differences in age, gender, comorbidities and recommended therapies between patients discharged for acute hospitalized HF and those followed-up at HF clinics. The Italian Working Group on Heart Failure has drafted a guidance document for the organisation of a national HF care network. Aims of the document are to describe tasks and requirements of the different health system points of contact for HF patients, and to define how diagnosis, management and care processes should be documented and shared among health-care professionals. The document classifies HF outpatient clinics in three groups: (i) community HF clinics, devoted to management of stable patients in strict liaison with primary care, periodic re-evaluation of emerging clinical needs and prompt treatment of impending destabilizations, (ii) hospital HF clinics, that target both new onset and chronic HF patients for diagnostic assessment, treatment planning and early post-discharge follow-up. They act as main referral for general internal medicine units and community clinics, and (iii) advanced HF clinics, directed at patients with severe disease or persistent clinical instability, candidates to advanced treatment options such as heart transplant or mechanical circulatory support. Those different types of HF clinics are integrated in a dedicated network for management of HF patients on a regional basis, according to geographic features. By sharing predefined protocols and communication systems, these HF networks integrate multi-professional providers to ensure continuity of care and patient empowerment. In conclusion, This guidance document details roles and interactions of cardiology specialists, so as to best exploit the added value of their input in the care of HF patients and is intended to promote a more efficient and effective organization of HF services. PMID:28751837

The distribution of zirconium and hafnium in terrestrial rocks, meteorites and the moon

NASA Technical Reports Server (NTRS)

Ehmann, W. D.; Chyi, L. L.; Garg, A. N.; Ali, M. Z.

1979-01-01

It is shown that Zr and Hf are not always fractionated in terrestrial igneous differentiation or regional metamorphism. Data do support a Zr-Hf fractionation in the differentiation of the alkali olivine magma at St. Helena Island. A strong Zr-Hf fractionation exists among lunar rocks and minerals. Ilmenite is an excellent concentrator of Zr and Hf and always exhibits high Zr/Hf ratios. Chondritic meteorites exhibit rather uniform Zr abundances and Zr/Hf ratios but a distinct Zr-Hf fractionation is observed among the eucrite and diogenite achondrites.

A novel ventricular restraint device (ASD) repetitively deliver Salvia miltiorrhiza to epicardium have good curative effects in heart failure management.

PubMed

Naveed, Muhammad; Wenhua, Li; Gang, Wang; Mohammad, Imran Shair; Abbas, Muhammad; Liao, Xiaoqian; Yang, Mengqi; Zhang, Li; Liu, Xiaolin; Qi, Xiaoming; Chen, Yineng; Jiadi, Lv; Ye, Linlan; Zhijie, Wang; Ding, Chen Ding; Feng, Yu; Xiaohui, Zhou

2017-11-01

A novel ventricular restraint is the non-transplant surgical option for the management of an end-stage dilated heart failure (HF). To expand the therapeutic techniques we design a novel ventricular restraint device (ASD) which has the ability to deliver a therapeutic drug directly to the heart. We deliver a Traditional Chinese Medicine (TCM) Salvia miltiorrhiza (Danshen Zhusheye) through active hydraulic ventricular support drug delivery system (ASD) and we hypothesize that it will show better results in HF management than the restraint device and drug alone. SD rats were selected and divided into five groups (n=6), Normal, HF, HF+SM (IV), HF+ASD, HF+ASD+SM groups respectively. Post myocardial infarction (MI), electrocardiography (ECG) showed abnormal heart function in all groups and HF+ASD+SM group showed a significant therapeutic improvement with respect to other treatment HF, HF+ASD, and HF+SM (IV) groups on day 30. The mechanical functions of the heart such as heart rate, LVEDP, and LVSP were brought to normal when treated with ASD+SM and show significant (P value<0.01) compared to other groups. BNP significantly declines in HF+ASD+SM group animals compared with other treatment groups. Masson's Trichrome staining was used to study histopathology of cardiac myocytes and quantification of fibrosis was assessed. The large blue fibrotic area was observed in HF, HF+ASD, and HF+SM (IV) groups while HF+ASD+SM showed negligible fibrotic myocyte at the end of study period (30days). This study proves that novel ASD device augments the therapeutic effect of the drug and delivers Salvia miltiorrhiza to the cardiomyocytes significantly as well as provides additional support to the dilated ventricle by the heart failure. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Heart failure in nursing home residents; a cross-sectional study to determine the prevalence and clinical characteristics.

PubMed

Daamen, Mariëlle A M J; Hamers, Jan P H; Gorgels, Anton P M; Brunner-La Rocca, Hans-Peter; Tan, Frans E S; van Dieijen-Visser, Marja P; Schols, Jos M G A

2015-12-16

Heart failure (HF) is expected to be highly prevalent in nursing home residents, but precise figures are scarce. The aim of this study was to determine the prevalence of HF in nursing home residents and to get insight in the clinical characteristics of residents with HF. The study followed a multi-centre cross-sectional design. Nursing home residents (n = 501) in the southern part of the Netherlands aged over 65 years and receiving long-term somatic or psychogeriatric care were included in the study. The diagnosis of HF and related characteristics were based on data collected from actual clinical examinations (including history, physical examination, ECG, cardiac markers and echocardiography), patient records and questionnaires. A panel of two cardiologists and a geriatrician ultimately judged the data to diagnose HF. The overall prevalence of HF in nursing home residents was 33 %, of which 52 % had HF with preserved ejection fraction. The symptoms dyspnoea and oedema and a cardiac history were more common in residents with HF. Diabetes mellitus, chronic obstructive pulmonary disease (COPD) were also more prevalent in those with HF. Residents with HF had a higher score on the Mini Mental State Examination. 54 % of those with HF where not known before, and in 31 % with a history of HF, this diagnosis was not confirmed by the expert panel. This study shows that HF is highly prevalent in nursing home residents with many unknown or falsely diagnosed with HF. Equal number of HF patients had reduced and preserved left-ventricular ejection fraction. The Netherlands National Trial Register NTR2663 (27-12-2010).

Characteristics and outcomes of heart failure-related hospitalization in adults with congenital heart disease.

PubMed

Moussa, Nidhal Ben; Karsenty, Clement; Pontnau, Florence; Malekzadeh-Milani, Sophie; Boudjemline, Younes; Legendre, Antoine; Bonnet, Damien; Iserin, Laurence; Ladouceur, Magalie

2017-05-01

Heart failure (HF) is the main cause of death in adult congenital heart disease (ACHD). We aimed to characterize HF-related hospitalization of patients with ACHD, and to determine HF risk factors and prognosis in this population. We prospectively included 471 patients with ACHD admitted to our unit over 24 months. Clinical and biological data and HF management were recorded. Major cardiovascular events were recorded for ACHD with HF. HF was the main reason for hospitalization in 13% of cases (76/583 hospitalizations). Patients with HF were significantly older (median age 44±14 years vs. 37±15 years; P<0.01), with more complex congenital heart disease (P=0.04). In the multivariable analysis, pulmonary arterial hypertension (odds ratio [OR] 6.2, 95% confidence interval [CI] 3.5-10.7), history of HF (OR 9.8, 95% CI 5.7-16.8) and history of atrial arrhythmia (OR 3.6, 95% CI 2.2-5.9) were significant risk factors for HF-related admissions (P<0.001). The mean hospital stay of patients with HF was longer (12.2 vs. 6.9 days; P<0.01), and 25% of patients required intensive care. Overall, 11/55 (20%) patients with HF died, 10/55 (18%) were readmitted for HF, and 6/55 (11%) had heart transplantation during the median follow-up of 18 months (95% CI 14-20 months). The risk of cardiovascular events was 19-fold higher after HF-related hospitalization. HF is emerging as a leading cause of morbidity and mortality in the ACHD population. Earlier diagnosis and more active management are required to improve outcomes of HF in ACHD. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Early postweaning exercise improves central leptin sensitivity in offspring of rat dams fed high-fat diet during pregnancy and lactation.

PubMed

Sun, Bo; Liang, Nu-Chu; Ewald, Erin R; Purcell, Ryan H; Boersma, Gretha J; Yan, Jianqun; Moran, Timothy H; Tamashiro, Kellie L K

2013-11-01

Maternal high-fat (HF) diet has long-term consequences on the metabolic phenotype of the offspring. Here, we determined the effects of postweaning exercise in offspring of rat dams fed HF diet during gestation and lactation. Pregnant Sprague-Dawley rats were maintained on chow or HF diet throughout gestation and lactation. All pups were weaned onto chow diet on postnatal day (PND) 21. At 4 wk of age, male pups were given free access to running wheels (RW) or remained sedentary (SED) for 3 wk, after which all rats remained sedentary, resulting in four groups: CHOW-SED, CHOW-RW, HF-SED, and HF-RW. Male HF offspring gained more body weight by PND7 compared with CHOW pups and maintained this weight difference through the entire experiment. Three weeks of postweaning exercise did not affect body weight gain in either CHOW or HF offspring, but reduced adiposity in HF offspring. Plasma leptin was decreased at the end of the 3-wk running period in HF-RW rats but was not different from HF-SED 9 wk after the exercise period ended. At 14 wk of age, intracerebroventricular injection of leptin suppressed food intake in CHOW-SED, CHOW-RW, and HF-RW, while it did not affect food intake in HF-SED group. At death, HF-RW rats also had higher leptin-induced phospho-STAT3 level in the arcuate nucleus than HF-SED rats. Both maternal HF diet and postweaning exercise had effects on hypothalamic neuropeptide and receptor mRNA expression in adult offspring. Our data suggest that postweaning exercise improves central leptin sensitivity and signaling in this model.

Validation of an automated electronic algorithm and "dashboard" to identify and characterize decompensated heart failure admissions across a medical center.

PubMed

Cox, Zachary L; Lewis, Connie M; Lai, Pikki; Lenihan, Daniel J

2017-01-01

We aim to validate the diagnostic performance of the first fully automatic, electronic heart failure (HF) identification algorithm and evaluate the implementation of an HF Dashboard system with 2 components: real-time identification of decompensated HF admissions and accurate characterization of disease characteristics and medical therapy. We constructed an HF identification algorithm requiring 3 of 4 identifiers: B-type natriuretic peptide >400 pg/mL; admitting HF diagnosis; history of HF International Classification of Disease, Ninth Revision, diagnosis codes; and intravenous diuretic administration. We validated the diagnostic accuracy of the components individually (n = 366) and combined in the HF algorithm (n = 150) compared with a blinded provider panel in 2 separate cohorts. We built an HF Dashboard within the electronic medical record characterizing the disease and medical therapies of HF admissions identified by the HF algorithm. We evaluated the HF Dashboard's performance over 26 months of clinical use. Individually, the algorithm components displayed variable sensitivity and specificity, respectively: B-type natriuretic peptide >400 pg/mL (89% and 87%); diuretic (80% and 92%); and International Classification of Disease, Ninth Revision, code (56% and 95%). The HF algorithm achieved a high specificity (95%), positive predictive value (82%), and negative predictive value (85%) but achieved limited sensitivity (56%) secondary to missing provider-generated identification data. The HF Dashboard identified and characterized 3147 HF admissions over 26 months. Automated identification and characterization systems can be developed and used with a substantial degree of specificity for the diagnosis of decompensated HF, although sensitivity is limited by clinical data input. Copyright © 2016 Elsevier Inc. All rights reserved.

System Architecture of Small Unmanned Aerial System for Flight Beyond Visual Line-of-Sight

DTIC Science & Technology

2015-09-17

Signal Strength PT = Transmitter Power GT = Transmitter antenna gain LT = Transmitter loss Lp = Propagation loss GR = Receiver antenna...gain (dBi) LR(db) = Receiver losses (dB) 15 Lm = Link margin (dB) PT = Transmitter Power (dBm) GT = Transmitter antenna gain (dBi) LT... Transmitter loss (dB) The maximum range is determined by four components, 1) Transmission, 2) Propagation, 3) Reception and 4) Link Margin

Heart failure as a general pandemic in Asia.

PubMed

Shimokawa, Hiroaki; Miura, Masanobu; Nochioka, Kotaro; Sakata, Yasuhiko

2015-09-01

Heart failure (HF) is an epidemic in healthcare worldwide, including Asia. It appears that HF will become more serious in the near future, with the epidemiological transition and ageing of the population. However, in contrast to Western countries, information on HF epidemiology is still limited in Asia, particularly in South Asia. In this review, we will briefly summarize available information regarding the current and future burden of HF in Asia, which indicates the importance of both primary prevention of underlying diseases of HF and secondary prevention, including management of ischaemic HF, HF with preserved EF, and HF in the elderly. © 2015 The Authors European Journal of Heart Failure © 2015 European Society of Cardiology.

Hafnium isotope results from mid-ocean ridges and Kerguelen.

USGS Publications Warehouse

Patchett, P.J.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanic rocks representing both extremes of the range of mantle Hf-Nd-Sr isotopic variation. Hf from critical mid-ocean ridge basalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/Sr-Sm/Nd-Lu/Hf fractionation relationships. At the other extreme of mantle isotopic compositions, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of Hf-Nd-Sr isotopic relatonships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean-island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation.-G.R.

Hafnium isotope results from mid-ocean ridges and Kerguelen

USGS Publications Warehouse

Jonathan, Patchett P.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanics representing both extremes of the range of mantle HfNdSr isotopic variation. Hf from critical mid-ocean ridgebasalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/SrSm/NdLu/Hf fractionation relationships. At the other extreme of mantle isotopic composition, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of HfNdSr c relationships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation. ?? 1983.

Electron Microprobe Analysis of Hf in Zircon: Suggestions for Improved Accuracy of a Difficult Measurement

NASA Astrophysics Data System (ADS)

Fournelle, J.; Hanchar, J. M.

2013-12-01

It is not commonly recognized as such, but the accurate measurement of Hf in zircon is not a trivial analytical issue. This is important to assess because Hf is often used as an internal standard for trace element analyses of zircon by LA-ICPMS. The issues pertaining to accuracy revolve around: (1) whether the Hf Ma or the La line is used; (2) what accelerating voltage is applied if Zr La is also measured, and (3) what standard for Hf is used. Weidenbach, et al.'s (2004) study of the 91500 zircon demonstrated the spread (in accuracy) of possible EPMA values for six EPMA labs, 2 of which used Hf Ma, 3 used Hf La, and one used Hf Lb, and standards ranged from HfO2, a ZrO2-HfO2 compound, Hf metal, and hafnon. Weidenbach, et al., used the ID-TIMS values as the correct value (0.695 wt.% Hf.), for which not one of the EPMA labs came close to that value (3 were low and 3 were high). Those data suggest: (1) that there is a systematic underestimation error of the 0.695 wt% Hf (ID-TIMS Hf) value if Hf Ma is used; most likely an issue with the matrix correction, as the analytical lines and absorption edges of Zr La, Si Ka and Hf Ma are rather tightly packed in the electromagnetic spectrum. Mass absorption coefficients are easily in error (e.g., Donovan's determination of the MAC of Hf by Si Ka of 5061 differs from the typically used Henke value of 5449 (Donovan et al, 2002); and (2) For utilization of the Hf La line, however, the second order Zr Ka line interferes with Hf La if the accelerating voltage is greater than 17.99 keV. If this higher keV is used and differential mode PHA is applied, only a portion of the interference is removed (e.g., removal of escape peaks), causing an overestimation of Hf content. Unfortunately, it is virtually impossible to apply an interference correction in this case, as it is impossible to locate Hf-free Zr probe standard. We have examined many of the combinations used by those six EPMA labs and concluded that the optimal EPMA is done with Hf La with the accelerating voltage under 18 keV (e.g. 17 keV is optimal), and also with synthetic stoichiometric hafnon as the standard. We have developed useful standards that are to be distributed to the community for those researchers working on this problem and can be obtained from the second author at jhanchar@mun.ca. The standards include synthetic stoichiometric undoped zircon and hafnon, and synthetic zircon doped with 2 wt. % Hf. Donovan et al. (2002) Probe for Windows: User's Guide and Reference Wiedenbeck, M., et al. (2004) Further characterisation of the 91500 zircon crystal. Geostandards and Geoanatytical Research, 28: 9-39.

The association between atrial fibrillation and cognitive function in patients with heart failure.

PubMed

Yang, Huifeng; Niu, Weihua; Zang, Xiaoying; Lin, Mei; Zhao, Yue

2017-02-01

Atrial fibrillation (AF) is associated with cognitive impairment in heart failure (HF). The purpose of this study was to examine whether AF independently predicted cognitive function in HF patients after controlling for more demographic, medical and psychological characteristics, and whether the timing of AF onset in relation to HF diagnosis independently contributed to cognitive function in HF patients with AF. A total of 188 hospitalized HF patients (62.8% male, age 66.3±10.6 years) completed cognitive function assessment with the Montreal Cognitive Assessment (MoCA). A history of AF, along with other medical characteristics, was ascertained through a review of participants' medical charts. The timing of AF onset in relation to HF diagnosis was categorized into AF occurring prior to HF diagnosis (i.e. prior AF) and AF developing after HF diagnosis (i.e. incident AF). Altogether 72 participants had a positive diagnostic history of AF. Specifically, 41 had prior AF, and 31 developed AF subsequently. In HF patients, AF was associated with poorer performance on cognitive function after controlling for more confounders (β=-0.112, ΔR 2 =0.010, p=0.046). Among HF patients with AF, incident AF independently predicted poorer cognitive function (β=-0.238, ΔR 2 =0.027, p=0.047). AF independently contributes to cognitive function in HF patients after adjusting for more confounding variables. The timing of AF onset in relation to HF diagnosis independently predicts cognitive function in HF patients with AF. Prospective studies are needed to elucidate possible mechanisms for the association between AF and cognitive function in HF populations.

Nocturnal Hot Flashes: Relationship to Objective Awakenings and Sleep Stage Transitions

PubMed Central

Bianchi, Matt T.; Kim, Semmie; Galvan, Thania; White, David P.; Joffe, Hadine

2016-01-01

Study Objectives: While women report sleep interruption secondary to nighttime hot flashes, the sleep disrupting impact of nocturnal hot flashes (HF) is not well characterized. We utilized a model of induced HF to investigate the relationship of nighttime HF to sleep architecture and sleep-stage transitions. Methods: Twenty-eight healthy, premenopausal volunteers received the depot gonadotropin-releasing hormone agonist (GnRHa) leuprolide to rapidly induce menopause, manifesting with HF. Sleep disruption was measured on 2 polysomnograms conducted before and after 4–5 weeks on leuprolide, when HF had developed. Results: 165 HF episodes were recorded objectively during 48 sleep studies (mean 3.4 HF/night). After standardizing to sleep-stage time distribution, the majority of HF were recorded during wake (51.0%) and stage N1 (18.8%). Sixty-six percent of HF occurred within 5 minutes of an awakening, with 80% occurring just before or during the awakening. Objective HF were not associated with sleep disruption as measured by increased transitions to wake or N1, but self-reported nocturnal HF correlated with an increase from pre- to post-leuprolide in the rate of transitions to wake (p = 0.01), and to N1 (p = 0.008). Conclusions: By isolating the effect of HF on sleep in women without the confound of age-related sleep changes associated with natural menopause, this experimental model shows that HF arise most commonly during N1 and wake, typically preceding or occurring simultaneously with wake episodes. Perception of HF, but not objective HF, is linked to increased sleep-stage transitions, suggesting that sleep disruption increases awareness of and memory for nighttime HF events. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT01116401. Citation: Bianchi MT, Kim S, Galvan T, White DP, Joffe H. Nocturnal hot flashes: relationship to objective awakenings and sleep stage transitions. J Clin Sleep Med 2016;12(7):1003–1009. PMID:26951410

Evolution of continental crust and mantle heterogeneity: Evidence from Hf isotopes

USGS Publications Warehouse

Jonathan, Patchett P.; Kouvo, O.; Hedge, C.E.; Tatsumoto, M.

1982-01-01

We present initial 176Hf/177 Hf ratios for many samples of continental crust 3.7-0.3 Gy old. Results are based chiefly on zircons (1% Hf) and whole rocks: zircons are shown to be reliable carriers of essentially the initial Hf itself when properly chosen on the basis of U-Pb studies. Pre-3.0 Gy gneisses were apparently derived from an unfractionated mantle, but both depleted and undepleted mantle are evident as magma sources from 2.9 Gy to present. This mantle was sampled mainly from major crustal growth episodes 2.8, 1.8 and 0.7 Gy ago, all of which show gross heterogeneity of 176Hf/177Hf in magma sources from ??Hf=0 to +14, or about 60% of the variability of the present mantle. The approximate ??Hf=2??Nd relationship in ancient and modern igneous rocks shows that 176Lu/177Hf fractionates in general twice as much as 147Sm/144Nd in mantle melting processes. This allows an estimation of the relative value of the unknown bulk solid/liquid distribution coefficient for Hf. DLu/DHf=??? 2.3 holds for most mantle source regions. For garnet to be an important residual mantle phase, it must hold Hf strongly in order to preserve Hf-Nd isotopic relationships. The ancient Hf initials are consistent with only a small proportion of recycled older cratons in new continental crust, and with quasi-continuous, episodic growth of the continental crust with time. However, recycling of crust less than 150 My old cannot realistically be detected using Hf initials. The mantle shows clearly the general positive ??Hf resulting from a residual geochemical state at least back to 2.9 Gy ago, and seems to have repeatedly possessed a similar degree of heterogeneity, rather than a continuously-developing depletion. This is consistent with a complex dynamic disequilibrium model for the creation, maintenance and destruction of heterogeneity in the mantle. ?? 1981 Springer-Verlag.

Sleepiness and activity in heart failure patients with reduced ejection fraction and central sleep-disordered breathing.

PubMed

Atalla, Angela; Carlisle, Thomas W; Simonds, Anita K; Cowie, Martin R; Morrell, Mary J

2017-06-01

Patients with heart failure (HF) and sleep disordered breathing (SDB) are typically not sleepy, unlike patients without heart failure. Previous work in HF patients with obstructive SDB suggested that sleepiness was associated with a reduction in daytime activity. The consequences of predominately central SDB on sleepiness in HF are less well understood. The aim of this study was to test the hypothesis that subjective sleepiness is associated with reduced daytime activity in HF patients with central SDB, compared to those without SDB. The Epworth Sleepiness Scale (ESS), nocturnal polysomnography, and 14 days of wrist watch actigraphy were used to assess subjective daytime sleepiness, nocturnal sleep and breathing, and 24-h activity levels, respectively. A total of 54 patients with HF were studied, nine had obstructive SDB and were removed from further analysis. Of the patients, 23 had HF with predominantly central SDB (HF-CSA; apnea-hypopnea index (AHI) median 20.6 (IQR 12.9-40.2)/h), and 22 had noSDB (HF-noSDB; AHI 3.7 (2.5-5.9)/h). The median patient age was 68 years (range 59-73 years). There were no significant differences either in ESS score (HF-CSA; 8 [4-10] vs. HF-noSDB; 8 (6-12); p = 0.49) or in duration of daytime activity (HF-CSA 14.5 (14.1-15.2) and HF-noSDB 15.1 (14.4-15.3) hours; p = 0.10) between the groups. HF patients with predominately central SDB are not subjectively sleepy compared to those without SDB, despite reduced sleep quality. We speculate that the lack of sleepiness (based on ESS score) may be due to increased sympathetic nerve activity, although further studies are needed due to the small number (n = 5) of sleepy HF-CSA patients. Daytime activity was not different between HF-noSDB and HF-CSA patients. Copyright © 2017. Published by Elsevier B.V.

Suomi NPP VIIRS solar diffuser screen transmittance model and its applications.

PubMed

Lei, Ning; Xiong, Xiaoxiong; Mcintire, Jeff

2017-11-01

The visible infrared imaging radiometer suite on the Suomi National Polar-orbiting Partnership satellite calibrates its reflective solar bands through observations of a sunlit solar diffuser (SD) panel. Sunlight passes through a perforated plate, referred to as the SD screen, before reaching the SD. It is critical to know whether the SD screen transmittance measured prelaunch is accurate. Several factors such as misalignments of the SD panel and the measurement apparatus could lead to errors in the measured transmittance and thus adversely impact on-orbit calibration quality through the SD. We develop a mathematical model to describe the transmittance as a function of the angles that incident light makes with the SD screen, and apply the model to fit the prelaunch measured transmittance. The results reveal that the model does not reproduce the measured transmittance unless the size of the apertures in the SD screen is quite different from the design value. We attribute the difference to the orientation alignment errors for the SD panel and the measurement apparatus. We model the alignment errors and apply our transmittance model to fit the prelaunch transmittance to retrieve the "true" transmittance. To use this model correctly, we also examine the finite source size effect on the transmittance. Furthermore, we compare the product of the retrieved "true" transmittance and the prelaunch SD bidirectional reflectance distribution function (BRDF) value to the value derived from on-orbit data to determine whether the prelaunch SD BRDF value is relatively accurate. The model is significant in that it can evaluate whether the SD screen transmittance measured prelaunch is accurate and help retrieve the true transmittance from the transmittance with measurement errors, consequently resulting in a more accurate sensor data product by the same amount.

Robust low-frequency spread-spectrum navigation system

DOEpatents

Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

2012-01-03

Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

Robust low-frequency spread-spectrum navigation system

DOEpatents

Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

2011-01-25

Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

Robust low-frequency spread-spectrum navigation system

DOEpatents

Smith, Stephen F; Moore, James A

2012-10-30

Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

Robust low-frequency spread-spectrum navigation system

DOEpatents

Smith, Stephen F [Loudon, TN; Moore, James A [Powell, TN

2009-12-01

Methods and apparatus are described for a navigation system. A process includes providing a plurality of transmitters distributed throughout a desired coverage area; locking the plurality of transmitters to a common timing reference; transmitting a signal from each of the plurality of transmitters. An apparatus includes a plurality of transmitters distributed throughout a desired coverage area; wherein each of the plurality of transmitters comprises a packet generator; and wherein the plurality of transmitters are locked to a common timing reference.

Pathologic and physiologic effects associated with long-term intracoelomic transmitters in captive Siberian sturgeon

USGS Publications Warehouse

Boone, S. Shaun; Divers, Stephen J.; Camus, Alvin C.; Peterson, Douglas C.; Jennings, Cecil A.; Shelton, James L.; Hernandez, Sonia M.

2015-01-01

Intracoelomic transmitters are commonly used to evaluate migratory patterns, distribution, and habitat use of many species of fish. Currently, transmitter implantation relies mostly on the assumption that transmitters do not cause any adverse physiological or pathological effects on the animal. To investigate these effects, we surgically implanted 60 Siberian Sturgeon Acipenser baeri with transmitters that weighed less than 2% of their body weight. Postoperative assessments were conducted at 1, 2, 8, 12, 26, and 55 weeks to evaluate surgical healing and transmitter retention. Blood samples were collected before and after the 55-week study for serum cortisol analysis. Overall transmitter loss was 32%. Minor to moderate adhesions were noted at necropsy but did not appear to affect organ function. One fish was noted to have an intraintestinal transmitter at necropsy, but the fish was in overall good health. Long-term transmitter presence does not appear to increase serum cortisol levels or affect overall growth more than nontransmitter fish. Although long-term telemetry studies can be undertaken with minimal concern for negative physiological or pathological effects from transmitters, researchers should be aware that transmitter loss rates may be higher than previously thought. Mechanisms for transmitter loss may include expulsion through the surgical incision, expulsion through the mucocutaneous junction between the large intestine and the vent, or intraintestinal capture and expulsion through the vent. Received February 10, 2013; accepted June 10, 2013

47 CFR 22.573 - Use of base transmitters as repeaters.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 2 2013-10-01 2013-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point regardless...

47 CFR 22.573 - Use of base transmitters as repeaters.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 2 2011-10-01 2011-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point regardless...

47 CFR 22.573 - Use of base transmitters as repeaters.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point regardless...

47 CFR 22.573 - Use of base transmitters as repeaters.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 2 2010-10-01 2010-10-01 false Use of base transmitters as repeaters. 22.573... of base transmitters as repeaters. As an additional function, base transmitters may be used as repeaters. Licensees must be able to turn the base transmitter on or off from the control point regardless...

Effects of C and Hf concentration on phase relations and microstructure of a wrought powder-metallurgy superalloy

NASA Technical Reports Server (NTRS)

Miner, R. V., Jr.

1977-01-01

NASA IIB-11, a candidate alloy for advanced temperature turbine engine disks, and four modifications with varying C and Hf concentrations were produced from prealloyed powders. Several notable effects of C and Hf concentration in the alloys were observed. Both the amount of the gamma-prime phase and its solvus temperature increased with decreasing C, but only the gamma-prime solvus was affected by Hf, increasing with increasing Hf. Hf also promoted a cellular gamma-prime precipitation. Hf was, however, about equally distributed between gamma-prime and gamma. Hf and C both affected the carbides formed. Increasing both promoted formation of an MC relative to that of an M6C.

Hardness and Second Phase Percentage of Ni-Ti-Hf Compounds After Heat Treatment at 700C

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2017-01-01

The Vickers hardness and second phase precipitation of three ternary intermetallic Ni-Ti-Hf compounds containing either 1, 3 or 5 at.% Hf were compared to 60-Nitinol (55 at.% Ni - 45 at.% Ti). Heat treatment either at 700 C or with a subsequent aging step, hardened the 3 and 5 at.% Hf-containing ternaries to approximately 620 HV (56 HRC). Heat treatment increased the hardness of the 1 at.% Hf compound by more than 25 percent. Average hardness of the 3 and 5 at.% Hf ternaries, though higher than that of the binary Ni-Ti or the Ni-Ti-Hf compound containing 1 at.% Hf, appeared to be fairly insensitive to the different heat treatments. There was a drastic reduction of fatigue-enhancing second phase precipitates for the 5 at.% Hf ternaries compared to the other compounds. These results should guide materials selection for development of aerospace componentry.

Clinical trials update from the Heart Failure Society of America Meeting 2009: FAST, IMPROVE-HF, COACH galectin-3 substudy, HF-ACTION nuclear substudy, DAD-HF, and MARVEL-1.

PubMed

Lainscak, Mitja; Coletta, Alison P; Sherwi, Nasser; Cleland, John G F

2010-02-01

This article presents findings and a commentary on late-breaking trials presented during the meeting of the Heart Failure Society of America in September 2009. Unpublished reports should be considered as preliminary, since analyses may change in the final publication. The FAST trial showed somewhat better performance of intrathoracic impedance for prediction of deterioration in patients with heart failure (HF) when compared with daily weighing. The IMPROVE-HF study reported the benefits of education on the management of patients with systolic HF. Galectin-3 appeared a useful method for improving risk stratification of patients with chronic HF in a substudy of the COACH trial. A nuclear substudy of the HF-ACTION trial failed to demonstrate that resting myocardial perfusion imaging, a measure of myocardial scar and viability, was clinically useful. A small randomized controlled trial (DAD-HF) suggested that the use of low-dose dopamine in patients with acutely decompensated HF was associated with less deterioration in renal function and less hypokalaemia. The MARVEL-1 trial raises further concerns about the safety of myoblast transplantation in ischaemic HF.

The rotational excitation of HF by H

NASA Astrophysics Data System (ADS)

Desrousseaux, Benjamin; Lique, François

2018-06-01

The HF molecule is a key tracer of molecular hydrogen in diffuse interstellar medium (ISM). Accurate modelling of the HF abundance in such media requires one to model its excitation by both radiation and collisions. In diffuse ISM, the dominant collisional partners are atomic and molecular hydrogen. We report quantum time-independent calculations of collisional cross-sections and rate coefficients for the rotational excitation of HF by H. The reactive hydrogen exchange channels are taken into account in the scattering calculations. For the first time, HF-H rate coefficients are provided for temperature ranging from 10 to 500 K. The strongest collision-induced rotational HF transitions are those with Δj = 1, and the order of magnitude of the new HF-H rate coefficients is similar to that of the HF-H2 ones previously computed. As a first application, we simulate the excitation of HF by both H and H2 in typical diffuse ISM. We show that, depending on the rotational transition, hydrogen atoms increase or decrease the simulated excitation temperatures compared to collisional excitation only due to H2 molecules. Such results suggest that the new HF-H collisional data have to be used for properly modelling the abundance of HF in diffuse ISM.

Predictors of memory performance among Taiwanese postmenopausal women with heart failure.

PubMed

Chou, Cheng-Chen; Pressler, Susan J; Giordani, Bruno

2014-09-01

There are no studies describing the nature of memory deficits among women with heart failure (HF). The aims of this study were to examine memory performance among Taiwanese women with HF compared with age- and education-matched healthy women, and to evaluate factors that explain memory performance in women with HF. Seventy-six women with HF and 64 healthy women were recruited in Taiwan. Women completed working, verbal, and visual memory tests; HF severity was collected from the medical records. Women with HF performed significantly worse than healthy women on tests of working memory and verbal memory. Among women with HF, older age explained poorer working memory, and older age, higher HF severity, more comorbidities, and systolic HF explained poorer verbal memory. Menopausal symptoms were not associated with memory performance. Results of the study validate findings of memory loss in HF patients from the United States and Europe in a culturally different sample of women. Working memory and verbal memory were worse in Taiwanese women with HF compared with healthy participants. Studies are needed to determine mechanisms of memory deficits in these women and develop interventions to improve memory. Copyright © 2014 Elsevier Inc. All rights reserved.

Influence of oxygen vacancies in ALD HfO2-x thin films on non-volatile resistive switching phenomena with a Ti/HfO2-x/Pt structure

NASA Astrophysics Data System (ADS)

Sokolov, Andrey Sergeevich; Jeon, Yu-Rim; Kim, Sohyeon; Ku, Boncheol; Lim, Donghwan; Han, Hoonhee; Chae, Myeong Gyoon; Lee, Jaeho; Ha, Beom Gil; Choi, Changhwan

2018-03-01

We report a modulation of oxygen vacancies profile in atomic layer deposition (ALD) HfO2-x thin films by reducing oxidant pulse time (0.7 s-0.1 s) and study its effect on resistive switching behavior with a Ti/HfO2-x/Pt structure. Hf 4f spectra of x-ray photoelectron microscopy (XPS) and depth profile confirm varied oxygen vacancies profiles by shifts of binding energies of Hf 4f5/2 and Hf 4f7/2 main peaks and its according HfO2-x sub-oxides for each device. The ultraviolet photoelectron spectroscopy (UPS) confirms different electron affinity (χ) of HfO2 and HfO2-x thin films, implying that barrier height at Ti/oxide interface is reduced. Current transport mechanism is dictated by Ohmic conduction in fully oxidized HfO2 thin films - Device A (0.7 s) and by Trap Filled Space Charge Limited Conduction (TF-SCLC) in less oxidized HfO2-x thin films - Device B (0.3 s) and Device C (0.1 s). A switching mechanism related to the oxygen vacancies modulation in Ti/HfO2-x/Pt based resistive random access memory (RRAM) devices is used to explain carefully notified current transport mechanism variations from device-to-device. A proper endurance and long-time retention characteristics of the devices are also obtained.

Small Volume Isotopic Analysis of Zircon Using LA-MC-ICP-MS U-Pb and Lu-Hf and Sub-ng Amounts of Hf in Solution

NASA Astrophysics Data System (ADS)

Bauer, A.; Horstwood, M. S.

2016-12-01

Crust-mantle evolution studies are greatly informed by zircon U-Pb and Lu-Hf isotopic datasets and the ease with which these data can now be acquired has seen their application become commonplace. In order to deconvolute geochemical change and interpret geologic variation in complexly zoned zircons, this information is most ideally obtained on the smallest volume of zircon by successive SIMS U-Pb and LA-MC-ICP-MS Lu-Hf isotopic analyses. However, due to variations in zircon growth zone geometry at depth, the Lu-Hf analysis may not relate to the lower volume U-Pb analysis, potentially causing inaccuracy of the resultant age-corrected Hf isotope signature. Laser ablation split-stream methods are applied to be certain that U-Pb and Lu-Hf data represent the same volume of zircon, however, the sampling volume remains relatively large at 40x30µm1. Coupled ID-TIMS U-Pb and solution MC-ICP-MS Lu-Hf work traditionally utilize whole-zircon dissolution ( 10-50ng Hf), which has the potential to homogenize different zones of geologic significance within an analysis. Conversely, modern ID-TIMS U-Pb methods utilize microsampling of zircon grains, often providing < 5ng Hf, thereby challenging conventional Lu-Hf acquisition protocols to achieve the required precision. In order to obtain usable precision on minimal zircon volumes, we developed laser ablation methods using successive 25um spot U-Pb and Lu-Hf ablation pits with a combined depth of 18um, and low-volume solution introduction methods without Hf-REE separation utilizing Hf amounts as low as 0.4ng, while retaining an uncertainty level of ca. 1 ɛHf for both methods. We investigated methods of Yb interference correction and the potential for matrix effects, with a particular focus on the accurate quantification of 176Lu/177Hf. These improvements reduce the minimum amount of material required for U-Pb and Hf isotopic analysis of zircon by about an order of magnitude. 1Ibanez-Mejia et al (2015). PreRes, 267, 285-310.

The initial Hf isotopic composition of the Earth

NASA Astrophysics Data System (ADS)

Bouvier, A.; Boyet, M. M.; Vervoort, J. D.; Patchett, P. J.

2011-12-01

One area of considerable activity in trying to understand the formation and evolution of Earth's crust is the isotopic analysis of Hf in parallel with Sm-Nd and U-Pb zircon studies, either to constrain early crustal growth and evolution [1], or as a complement to detrital zircon studies [2]. The 176Lu decay constant deduced from early planetary and Earth materials have different values. It has been suggested that a period of irradiation in the early Solar System affected the 176Hf production rate in meteoritic and planetary materials [3,4]. In this scenario, the initial Hf isotopic composition of the Solar System and the Earth would be ~4 ∈Hf units lower, affecting tremendously the interpretation of the differentiation history of the early Earth. We investigated Lu-Hf compositions of calcium-aluminum-rich inclusions, the oldest known objects of the Solar System dated at 4568 Ma [5], to assess the possibility of neutrino irradiation in the solar nebula. Here we report high-precision 176Lu-176Hf systematics of leached and unleached, and spiked and unspiked, bulk fractions and mineral separates of 6 individual CAIs from 2 CV3 chondrites. Isotopic analyses were carried out by Neptune MC-ICPMS at ASU. Analytical details are in [6,7]. The unspiked Hf fractions reveal stable isotope anomalies of μ178Hf= 20 ± 6 and μ180Hf= 31 ± 9 (2SD) for the CAI B4 fractions (n=3) and μ178Hf= -4 ± 10 and μ180Hf= 2 ± 10 (n=2) for BCR-2 relative to the JMC 475 Hf standard. Further high-precision analysis of unspiked Sm and Nd fractions of the samples will be made to correct from nucleosynthetic or neutron capture anomalies [8]. Such Hf stable isotopic anomalies predict no more than 50ppm correction on 176Hf/177Hf. At this stage, we have thus regressed together the spiked and unspiked Hf compositions of CAI fractions (n=13) for isochron calculations. The slope of the Lu-Hf isochron is 0.0882 ± 0.0026 (2SD) which corresponds to a 176Lu decay constant value of 1.852 (± 0.052) ×10-11×y-1 consistent with the "terrestrial" determination [9,10]. We do not find evidence of 176Hf excesses in the CAI Lu-Hf systematics which excludes the possibility of neutrino irradiation to explain the anomalous Lu-Hf isochron ages of eucrite and angrite meteorites [3]. The initial 176Hf/177Hf of the CAIs and thus of the Solar System is 0.28286 ± 0.00011 which is consistent with the estimates of 0.28279 ± 0.00002 obtained using the modern CHUR composition [6] and the terrestrial decay constant [9,10]. This last composition remains the best estimate for the initial 176Hf/177Hf of the Earth. [1] Harrison. AREP Sci. 2009 37, 479. [2] Sun et al. Prec. Res. 2009 172, 99. [3] Albarède et al. GCA 2006 70, 1261. [4] Thrane et al. Astrophys. J. 2010 717, 861-867. [5] Bouvier & Wadhwa. Nat. Geosci. 2010 3, 637. [6] Bouvier et al. EPSL 2008 273, 48. [7] Münker et al. G3 2001 2. [8] Sprung et al. EPSL 2010 295, 1. [9] Scherer et al. Science 2001 293, 683. [10] Söderlund et al. EPSL 2004 219, 311.

Influence of Etching Protocol and Silane Treatment with a Universal Adhesive on Lithium Disilicate Bond Strength.

PubMed

Kalavacharla, V K; Lawson, N C; Ramp, L C; Burgess, J O

2015-01-01

To measure the effects of hydrofluoric acid (HF) etching and silane prior to the application of a universal adhesive on the bond strength between lithium disilicate and a resin. Sixty blocks of lithium disilicate (e.max CAD, Ivoclar Vivadent) were sectioned into coupons and polished. Specimens were divided into six groups (n=10) based on surface pretreatments, as follows: 1) no treatment (control); 2) 5% HF etch for 20 seconds (5HF); 3) 9.5% HF etch for 60 seconds (9.5HF); 4) silane with no HF (S); 5) 5% HF for 20 seconds + silane (5HFS); and 6) 9.5% HF for 60 seconds + silane (9.5HFS). All etching was followed by rinsing, and all silane was applied in one coat for 20 seconds and then dried. The universal adhesive (Scotchbond Universal, 3M ESPE) was applied onto the pretreated ceramic surface, air thinned, and light cured for 10 seconds. A 1.5-mm-diameter plastic tube filled with Z100 composite (3M ESPE) was applied over the bonded ceramic surface and light cured for 20 seconds on all four sides. The specimens were thermocycled for 10,000 cycles (5°C-50°C/15 s dwell time). Specimens were loaded until failure using a universal testing machine at a crosshead speed of 1 mm/min. The peak failure load was used to calculate the shear bond strength. Scanning electron microscopy images were taken of representative e.max specimens from each group. A two-way analysis of variance (ANOVA) determined that there were significant differences between HF etching, silane treatment, and the interaction between HF and silane treatment (p<0.01). Silane treatment provided higher shear bond strength regardless of the use or concentration of the HF etchant. Individual one-way ANOVA and Tukey post hoc analyses were performed for each silane group. Shear bond strength values for each etch time were significantly different (p<0.01) and could be divided into significantly different groups based on silane treatment: no silane treatment: 0 HF < 5% HF < 9.5% HF; and RelyX silane treatment: 0 HF < 5% HF and 9.5% HF. Both HF and silane treatment significantly improved the bond strength between resin and lithium disilicate when used with a universal adhesive.

Mango Supplementation Modulates Gut Microbial Dysbiosis and Short-Chain Fatty Acid Production Independent of Body Weight Reduction in C57BL/6 Mice Fed a High-Fat Diet.

PubMed

Ojo, Babajide; El-Rassi, Guadalupe Davila; Payton, Mark E; Perkins-Veazie, Penelope; Clarke, Stephen; Smith, Brenda J; Lucas, Edralin A

2016-08-01

High-fat (HF) diet-induced obesity is associated with changes in the gut microbiota. Fiber and other bioactive compounds in plant-based foods are suggested to prevent gut dysbiosis brought on by HF feeding. Mango is high in fiber and has been reported to have anti-obesogenic, hypoglycemic, and immunomodulatory properties. We investigated the effects of freeze-dried mango pulp combined with an HF diet on the cecal microbial population and its relation to body composition, lipids, glucose parameters, short-chain fatty acid (SCFA) production, and gut inflammatory markers in a mouse model of diet-induced obesity. Six-wk-old male C57BL/6 mice were randomly assigned to 1 of 4 dietary treatment groups: control (AIN-93M, 10% fat kcal), HF (60% fat kcal), and HF + 1% or 10% mango (HF+1%M or HF+10%M, wt:wt) for 12 wk. The cecal microbial population was assessed by use of 16S rDNA sequencing. Body composition, plasma glucose and lipids, cecal and fecal SCFAs, and mRNA abundance of inflammatory markers in the ileum and colonic lamina propria were assessed. Compared with the control group, HF feeding significantly reduced (P < 0.05) 1 operational taxonomic unit (OTU) of the genus Bifidobacteria (64-fold) and 5 OTUs of the genus Akkermansia (≥16-fold). This reduction was prevented in the HF+10%M group, members of which had 10% higher final body weight compared with the HF group (P = 0.01) and similar fasting blood glucose concentrations (P = 0.24). The HF+10%M group had 135% (P = 0.004) and 133% (P < 0.0001) greater fecal acetic and n-butyric acids concentrations than the HF group, suggesting greater microbial fermentation. Furthermore, a 59% greater colonic interleukin 10 (Il10) gene expression was observed in the HF+10%M group than in the HF group (P = 0.048), indicating modulation of gut inflammation. The HF+1%M group generally did not differ from the HF group. The addition of mango to an HF diet modulated the gut microbiota and production of SCFAs in C57BL/6 mice; these changes may improve gut tolerance to the insult of an HF diet. © 2016 American Society for Nutrition.

Examining mortality among formerly homeless adults enrolled in Housing First: An observational study.

PubMed

Henwood, Benjamin F; Byrne, Thomas; Scriber, Brynn

2015-12-04

Adults who experience prolonged homelessness have mortality rates 3 to 4 times that of the general population. Housing First (HF) is an evidence-based practice that effectively ends chronic homelessness, yet there has been virtually no research on premature mortality among HF enrollees. In the United States, this gap in the literature exists despite research that has suggested chronically homeless adults constitute an aging cohort, with nearly half aged 50 years old or older. This observational study examined mortality among formerly homeless adults in an HF program. We examined death rates and causes of death among HF participants and assessed the timing and predictors of death among HF participants following entry into housing. We also compared mortality rates between HF participants and (a) members of the general population and (b) individuals experiencing homelessness. We supplemented these analyses with a comparison of the causes of death and characteristics of decedents in the HF program with a sample of adults identified as homeless in the same city at the time of death through a formal review process. The majority of decedents in both groups were between the ages of 45 and 64 at their time of death; the average age at death for HF participants was 57, compared to 53 for individuals in the homeless sample. Among those in the HF group, 72% died from natural causes, compared to 49% from the homeless group. This included 21% of HF participants and 7% from the homeless group who died from cancer. Among homeless adults, 40% died from an accident, which was significantly more than the 14% of HF participants who died from an accident. HIV or other infectious diseases contributed to 13% of homeless deaths compared to only 2% of HF participants. Hypothermia contributed to 6% of homeless deaths, which was not a cause of death for HF participants. Results suggest HF participants face excess mortality in comparison to members of the general population and that mortality rates among HF participants are higher than among those reported among members of the general homeless population in prior studies. However, findings also suggest that causes of death may differ between HF participants and their homeless counterparts. Specifically, chronic diseases appear to be more prominent causes of death among HF participants, indicating the potential need for integrating medical support and end-of-life care in HF.

Organization of heart failure management in European Society of Cardiology member countries: survey of the Heart Failure Association of the European Society of Cardiology in collaboration with the Heart Failure National Societies/Working Groups.

PubMed

Seferovic, Petar M; Stoerk, Stefan; Filippatos, Gerasimos; Mareev, Viacheslav; Kavoliuniene, Ausra; Ristic, Arsen D; Ponikowski, Piotr; McMurray, John; Maggioni, Aldo; Ruschitzka, Frank; van Veldhuisen, Dirk J; Coats, Andrew; Piepoli, Massimo; McDonagh, Theresa; Riley, Jillian; Hoes, Arno; Pieske, Burkert; Dobric, Milan; Papp, Zoltan; Mebazaa, Alexandre; Parissis, John; Ben Gal, Tuvia; Vinereanu, Dragos; Brito, Dulce; Altenberger, Johann; Gatzov, Plamen; Milinkovic, Ivan; Hradec, Jaromír; Trochu, Jean-Noel; Amir, Offer; Moura, Brenda; Lainscak, Mitja; Comin, Josep; Wikström, Gerhard; Anker, Stefan

2013-09-01

The aim of this document was to obtain a real-life contemporary analysis of the demographics and heart failure (HF) statistics, as well as the organization and major activities of the Heart Failure National Societies (HFNS) in European Society of Cardiology (ESC) member countries. Data from 33 countries were collected from HFNS presidents/representatives during the first Heart Failure Association HFNS Summit (Belgrade, Serbia, 29 October 2011). Data on incidence and/or prevalence of HF were available for 22 countries, and the prevalence of HF ranged between 1% and 3%. In five European and one non-European ESC country, heart transplantation was reported as not available. Natriuretic peptides and echocardiography are routinely applied in the management of acute HF in the median of 80% and 90% of centres, respectively. Eastern European and Mediterranean countries have lower availability of natriuretic peptide testing for acute HF patients, compared with other European countries. Almost all countries have organizations dealing specifically with HF. HFNS societies for HF patients exist in only 12, while in 16 countries HF patient education programmes are active. Most HFNS reported that no national HF registry exists in their country. Fifteen HFNS produced national HF guidelines, while 19 have translated the ESC HF guidelines. Most HFNS (n = 23) participated in the organization of the European HF Awareness Day. This document demonstrated significant heterogeneity in the organization of HF management, and activities of the national HF working groups/associations. High availability of natriuretic peptide and echocardiographic measurements was revealed, with differences between developed countries and countries in transition.

NT-proBNP and Heart Failure Risk Among Individuals With and Without Obesity: The ARIC Study

PubMed Central

Ndumele, Chiadi E.; Matsushita, Kunihiro; Sang, Yingying; Lazo, Mariana; Agarwal, Sunil K.; Nambi, Vijay; Deswal, Anita; Blumenthal, Roger S.; Ballantyne, Christie M.; Coresh, Josef; Selvin, Elizabeth

2016-01-01

Background Obesity is a risk factor for heart failure (HF), but is associated with lower N-terminal of pro-Brain Natriuretic Peptide (NT-proBNP) levels. It is unclear whether the prognostic value and implications of NT-proBNP levels for HF risk differ across body mass index (BMI) categories. Methods and Results We followed 12,230 ARIC participants free of prior HF at baseline (visit 2, 1990–1992) with BMI ≥18.5 kg/m2. We quantified and compared the relative and absolute risk associations of NT-proBNP with incident HF across BMI categories. There were 1,861 HF events during a median 20.6 years of follow-up. Despite increased HF risk in obesity, a weak inverse association was seen between baseline BMI and NT-proBNP levels (r = −0.10). Nevertheless, higher baseline NT-proBNP was associated with increased HF risk in all BMI categories. NT-proBNP improved HF risk prediction overall and even among those with severe obesity (BMI ≥35 kg/m2; improvement in c-statistic +0.032 [95% CI 0.011–0.053]). However, given higher HF rates among those with obesity, at each NT-proBNP level, higher BMI was associated with greater absolute HF risk. Indeed, among those with NT-proBNP 100 to < 200 pg/ml, the average 10-year HF risk was <5% among normal weight individuals but >10% if severely obese. Conclusions Despite its inverse relationship with BMI, NT-proBNP provides significant prognostic information regarding the risk of developing HF even among individuals with obesity. Given the higher baseline HF risk among persons with obesity, even slight elevations in NT-proBNP may have implications for increased absolute HF risk in this population. PMID:26746175

Real-world heart failure management in 10,910 patients with chronic heart failure in the Netherlands : Design and rationale of the Chronic Heart failure ESC guideline-based Cardiology practice Quality project (CHECK-HF) registry.

PubMed

Brugts, J J; Linssen, G C M; Hoes, A W; Brunner-La Rocca, H P

2018-05-01

Data from patient registries give insight into the management of patients with heart failure (HF), but actual data from unselected real-world HF patients are scarce. Therefore, we performed a cross sectional study of current HF care in the period 2013-2016 among more than 10,000 unselected HF patients at HF outpatient clinics in the Netherlands. In 34 participating centres, all 10,910 patients with chronic HF treated at cardiology centres were included in the CHECK-HF registry. Of these, most (96%) were managed at a specific HF outpatient clinic. Heart failure was typically diagnosed according to the ESC guidelines 2012, based on signs, symptoms and structural and/or functional cardiac abnormalities. Information on diagnostics, treatment and co-morbidities were recorded, with specific focus on drug therapy and devices. In our cohort, the mean age was 73 years (SD 12) and 60% were male. Frequent co-morbidities reported in the patient records were diabetes mellitus 30%, hypertension 43%, COPD 19%, and renal insufficiency 58%. In 47% of the patients, ischaemia was the origin of HF. In our registry, the prevalence of HF with preserved ejection fraction was 21%. The CHECK-HF registry will provide insight into the current, real world management of patient with chronic HF, including HF with reduced ejection fraction, preserved ejection fraction and mid-range ejection fraction, that will help define ways to improve quality of care. Drug and device therapy and guideline adherence as well as interactions with age, gender and co-morbidities will receive specific attention.

Influence of Prior Heart Failure Hospitalization on Cardiovascular Events in Patients with Reduced and Preserved Ejection Fraction

PubMed Central

Bello, Natalie A.; Claggett, Brian; Desai, Akshay S.; McMurray, John J.V.; Granger, Christopher B.; Yusuf, Salim; Swedberg, Karl; Pfeffer, Marc A.; Solomon, Scott D.

2014-01-01

Background Hospitalization for acute heart failure (HF) is associated with high rates of subsequent mortality and readmission. We assessed the influence of the time interval between prior HF hospitalization and randomization in the CHARM trials on clinical outcomes in patients with both reduced and preserved ejection fraction. Methods and Results CHARM enrolled 7,599 patients with NYHA class II-IV heart failure, of whom 5,426 had a history of prior HF hospitalization. Cox proportional hazards regression models were utilized to assess the association between time from prior HF hospitalization and randomization and the primary outcome of cardiovascular death or unplanned admission to hospital for the management of worsening HF over a median of 36.6 months. For patients with HF and reduced (HFrEF) or preserved (HFpEF) ejection fraction, rates of CV mortality and HF hospitalization were higher among patients with prior HF hospitalization than those without. The risk for mortality and hospitalization varied inversely with the time interval between hospitalization and randomization. Rates were higher for HFrEF patients within each category. Event rates for those with HFpEF and a HF hospitalization in the 6 months prior to randomization were comparable to the rate in HFrEF patients with no prior HF hospitalization. Conclusions Rates of CV death or HF hospitalization are greatest in those who have been previously hospitalized for HF. Independent of EF, rates of death and readmission decline as time from HF hospitalization to trial enrollment increased. Recent HF hospitalization identifies a high risk population for future clinical trials in HFrEF and HFpEF. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT00634400. PMID:24874200

[Type B natriuretic peptide in the diagnosis of heart failure with preserved systolic function].

PubMed

Castro, A; Dias, P; Pereira, M; Pimenta, J; Friões, F; Rodrigues, R; Ferreira, A; Bettencourt, P

2001-11-01

Heart failure (HF) with preserved left ventricular systolic function (LVSF) is observed in up to 50% patients with HF. There is no consensus on non-invasive diagnosis of this entity. Evaluation of B-type natriuretic peptide (BNP) in the diagnosis of HF with preserved left ventricular systolic function. Prospective study. One hundred and seventy-six consecutive patients with suspected HF were evaluated. Patients were classified as having HF with preserved LVSF, if they had symptoms and signs of HF, an ejection fraction greater than 40% and an abnormal Doppler pattern of the mitral inflow or atrial fibrilation and no other causes for the symptoms. All patients had a 12-lead EKG, chest roentgenogram, simple spirometry, M-mode and 2D echocardiogram with pulsed Doppler study of transmitral inflow and determination of plasma BNP levels. Of the 176 patients, 65 had ejection fraction greater than 40%. Of these patients 46 were classified as having HF with preserved LVSF and 19 as not having HF. Patients with HF and preserved LVSF were older, had a higher systolic blood pressure (SBP), less pathologic Q waves on ECG and higher left ventricular ejection fraction and plasma BNP than patients without HF. Multivariate analysis revealed that BNP and SBP were independently associated with the diagnosis of HF. The accuracy of BNP in the diagnosis of HF with preserved LVSF evaluated by the area under the receiver operating characteristic curve was 0.94. These results suggest that the measurement of BNP levels can help clinicians in the diagnosis of HF with preserved LVSF. Whether BNP levels might be used in clinical practice as a test for the diagnosis of HF with preserved LVSF is a question that merits further studies.

Heart failure in pregnant women with cardiac disease: data from the ROPAC.

PubMed

Ruys, Titia P E; Roos-Hesselink, Jolien W; Hall, Roger; Subirana-Domènech, Maria T; Grando-Ting, Jennifer; Estensen, Mette; Crepaz, Roberto; Fesslova, Vlasta; Gurvitz, Michelle; De Backer, Julie; Johnson, Mark R; Pieper, Petronella G

2014-02-01

Heart failure (HF) is one of the most important complications in pregnant women with heart disease, causing maternal and fetal mortality and morbidity. This is an international observational registry of patients with structural heart disease during pregnancy. Sixty hospitals in 28 countries enrolled 1321 women between 2007 and 2011. Pregnant women with valvular heart disease, congenital heart disease, ischaemic heart disease, or cardiomyopathy could be included. Main outcome measures were onset and predictors of HF and maternal and fetal death. In total, 173 (13.1%) of the 1321 patients developed HF, making HF the most common major cardiovascular complication during pregnancy. Baseline parameters associated with HF were New York Heart Association class ≥ 3, signs of HF, WHO category ≥ 3, cardiomyopathy or pulmonary hypertension. HF occurred at a median time of 31 weeks gestation (IQR 23-40) with the highest incidence at the end of the second trimester (34%) or peripartum (31%). Maternal mortality was higher in patients with HF (4.8% in patients with HF and 0.5% in those without HF p<0.001). Pre-eclampsia was strongly related to HF (OR 7.1, 95% CI 3.9 to 13.2, p<0.001). Fetal death and the incidence of preterm birth were higher in women with HF compared to women without HF (4.6% vs 1.2%, p=0.001; and 30% vs 13%, p=0.001). HF was the most common complication during pregnancy, and occurred typically at the end of the second trimester, or after birth. It was most common in women with cardiomyopathy or pulmonary hypertension and was strongly associated with pre-eclampsia and an adverse maternal and perinatal outcome.

Contemporary Epidemiology of Heart Failure in Fee-For-Service Medicare Beneficiaries Across Healthcare Settings.

PubMed

Khera, Rohan; Pandey, Ambarish; Ayers, Colby R; Agusala, Vijay; Pruitt, Sandi L; Halm, Ethan A; Drazner, Mark H; Das, Sandeep R; de Lemos, James A; Berry, Jarett D

2017-11-01

To assess the current landscape of the heart failure (HF) epidemic and provide targets for future health policy interventions in Medicare, a contemporary appraisal of its epidemiology across inpatient and outpatient care settings is needed. In a national 5% sample of Medicare beneficiaries from 2002 to 2013, we identified a cohort of 2 331 939 unique fee-for-service Medicare beneficiaries ≥65-years-old followed for all inpatient and outpatient encounters over a 10-year period (2004-2013). Preexisting HF was defined by any HF encounter during the first year, and incident HF with either 1 inpatient or 2 outpatient HF encounters. Mean age of the cohort was 72 years; 57% were women, and 86% and 8% were white and black, respectively. Within this cohort, 518 223 patients had preexisting HF, and 349 826 had a new diagnosis of HF during the study period. During 2004 to 2013, the rates of incident HF declined 32%, from 38.7 per 1000 (2004) to 26.2 per 1000 beneficiaries (2013). In contrast, prevalent (preexisting + incident) HF increased during our study period from 162 per 1000 (2004) to 172 per 1000 beneficiaries (2013) ( P trend <0.001 for both). Finally, the overall 1-year mortality among patients with incident HF is high (24.7%) with a 0.4% absolute decline annually during the study period, with a more pronounced decrease among those diagnosed in an inpatient versus outpatient setting ( P interaction <0.001) CONCLUSIONS: In recent years, there have been substantial changes in the epidemiology of HF in Medicare beneficiaries, with a decline in incident HF and a decrease in 1-year HF mortality, whereas the overall burden of HF continues to increase. © 2017 American Heart Association, Inc.

Heart failure in patients admitted for acute coronary syndromes: A report from a large national registry.

PubMed

Jeger, Raban V; Pfister, Otmar; Radovanovic, Dragana; Eberli, Franz R; Rickli, Hans; Urban, Philip; Pedrazzini, Giovanni; Stauffer, Jean-Christophe; Nossen, Jörg; Erne, Paul

2017-10-01

Data on temporal trends of heart failure (HF) in acute coronary syndrome (ACS) are scarce. Improved treatment options may have led to lower case-fatality rates (CFRs) during the last years in ACS complicated by HF. Patients of the nationwide Acute Myocardial Infarction in Switzerland (AMIS)-Plus ACS registry were analyzed from 2000 to 2014. Of 36 366 ACS patients, 3376 (9.3%) had acute or chronic HF, 2111 (5.8%) de novo acute HF (AHF), 964 (2.7%) chronic HF (CHF), and 301 (0.8%) acute decompensated CHF (ADCHF). In-hospital CFRs were highest in patients with ADCHF (32.6%) and de novo AHF (29.7%), followed by patients with CHF (12.9%) and without HF (3.2%, P < 0.001). Although in-hospital CFRs gradually decreased in CHF patients (14.3% to 4.5%, P = 0.003) and patients without HF (3.5% to 2.2%, P < 0.001), they remained high in patients with ADCHF (36.4% to 40.0%, P = 0.45) and de novo AHF (50.0% to 29.4%, P = 0.37). Although there was an increase in specific ACS therapies in the cohort over time, ACS patients with HF received significantly less pharmacological and interventional ACS therapies than patients without HF. There was no significant change in HF medication rates except less frequent use of β-blockers and diuretics in de novo AHF patients in recent years. HF is present in 1 out of 10 patients presenting with ACS and is associated with high in-hospital CFRs, particularly in acute HF. Although advances in ACS therapy improved in-hospital CFRs in patients with no HF or CHF, CFRs remained unchanged and high in patients with acute HF and ACS over the last decade. © 2017 Wiley Periodicals, Inc.

The pecan nut (Carya illinoinensis) and its oil and polyphenolic fractions differentially modulate lipid metabolism and the antioxidant enzyme activities in rats fed high-fat diets.

PubMed

Domínguez-Avila, Jesús A; Alvarez-Parrilla, Emilio; López-Díaz, José A; Maldonado-Mendoza, Ignacio E; Gómez-García, María Del Consuelo; de la Rosa, Laura A

2015-02-01

Tree nuts such as pecans (Carya illinoinensis) contain mostly oil but are also a source of polyphenols. Nut consumption has been linked to a reduction in serum lipid levels and oxidative stress. These effects have been attributed to the oil while overlooking the potential contribution of the polyphenols. Because the evidence regarding each fraction's bioactivity is scarce, we administered high-fat (HF) diets to male Wistar rats, supplementing them with pecan oil (HF+PO), pecan polyphenols (HF+PP) or whole pecans (HF+WP), and analysed the effects of each fraction. The HF diet increased the serum leptin and total cholesterol (TC) with respect to the control levels. The HF+WP diet prevented hyperleptinemia and decreased the TC compared with the control. The HF+WP diet upregulated the hepatic expression of apolipoprotein B and LDL receptor mRNAs with respect to the HF levels. The HF+PO diet reduced the level of triacylglycerols compared with the control. The HF+PP diet stimulated the hepatic expression of liver X receptor alpha mRNA. The HF+WP diet increased the activities of hepatic catalase, glutathione peroxidase and glutathione S transferase compared with the control, and decreased the degree of lipid peroxidation compared with the HF diet. The most bioactive diet was the WP diet. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficacy of using radio transmitters to monitor least tern chicks

USGS Publications Warehouse

Whittier, Joanna B.; Leslie, David M.

2005-01-01

Little is known about Least Tern (Sterna antillarum) chicks from the time they leave the nest until fledging because they are highly mobile and cryptically colored. We evaluated the efficacy of using radiotelemetry to monitor Interior Least Tern (S. a. athalassos) chicks at Salt Plains National Wildlife Refuge, Oklahoma. In 1999, we attached radio transmitters to 26 Least Tern chicks and tracked them for 2-17 days. No adults abandoned their chicks after transmitters were attached. Transmitters did not appear to alter growth rates of transmittered chicks (P = 0.36) or prevent feather growth, although dermal irritation was observed on one chick. However, without frequent reattachment, transmitters generally did not remain on chicks <1 week old for more than 2 days because of feather growth and transmitter removal, presumably by adult terns. Although the presence of transmitters did not adversely affect Least Tern chicks, future assessments should investigate nonintrusive methods to improve retention of transmitters on young chicks and reduce the number of times that chicks need to be handled.

Subcutaneous implantation of satellite transmitters with percutaneous antennae into male polar bears (Ursus maritimus)

USGS Publications Warehouse

Mulcahy, Daniel M.; Garner, Gerald W.

1999-01-01

Male polar bears (Ursus maritimus) have not been successfully instrumented with satellite transmitters because they readily shed collar-mounted transmitters. Seven male polar bears were captured on the pack ice off the northern coast of Alaska and surgically implanted with satellite transmitters with percutaneous antennae into the subcutaneous space of the dorsal cervical region. Transmitters failed prematurely with lifetimes of 30-161 days (x̄ = 97 days). Efforts to relocate implanted bears after transmitters failed were not successful. The mean number of location solutions per transmitter was 204 (range 118-369). An average of 10% and 19% of the locations were accurate to <150 m and to 150-350 m, respectively. Our successful tracking of male polar bears, the high quality of locations obtained from transmitters with percutaneous antennae implanted in the subcutaneous space, and the low visibility of such units make further technical development worthwhile if the reason for premature failure of the transmitters can be determined.

Lu-Hf total-rock age for the Amîtsoq gneisses, West Greenland

USGS Publications Warehouse

Pettingill, H.S.; Patchett, P.J.

1981-01-01

Lu-Hf total-rock data for the Amîtsoq gneisses of West Greenland yield an age of 3.55±0.22Gy(2σ), based on the decay constant λ176Lu=1.96×10−11y−1, and an initial176Hf/177Hf ratio of 0.280482±33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9 Gy, zircons from two of the samples have remained on the total-rock line, and define points close to the initial Hf ratio. The initial176Hf/177Hf lies close to a chondritic Hf isotopic evolution curve from 4.55 Gy to present. This is consistent with the igneous precursors to the Amîtsoq gneisses having been derived from the mantle at or shortly before 3.6 Gy. Anomalous relationships between Hf concentration and the176Lu/177Hf ratio may suggest that trace element abundances in the Amîtsoq gneisses are partly controlled by processes related to metamorphism.

Lu-Hf total-rock age for the Amitsoq gneisses, West Greenland

NASA Technical Reports Server (NTRS)

Pettingill, H. S.; Patchett, P. J.

1981-01-01

Lu-Hf total-rock data for the Amitsoq gneisses of West Greenland yield an age of 3.55 + or - 0.22 billion years, based on the decay constant for Lu-176 of 1.96 x 10 to the -11th/year, and an initial Hf-176/Hf-177 ratio of 0.280482 + or - 33. The result is in good agreement with Rb-Sr total-rock and U-Pb zircon ages. In spite of severe metamorphism of the area at 2.9 billion years, zircons from two of the samples have remained on the total-rock line, and define points close to the initial Hf ratio. The initial Hf-176/Hf-177 lies close to a chondritic Hf isotopic evolution curve from 4.55 billion years to present. This is consistent with the igneous precursors to the Amitsoq gneisses having been derived from the mantle at or shortly before 3.6 billion years. Anomalous relationships between Hf concentration and the Lu-176/Hf-177 ratio may suggest that trace element abundances in the Amitsoq gneisses are partly controlled by processes related to metamorphism.

Anticoagulant therapy and outcomes in patients with prior or acute heart failure and acute coronary syndromes: Insights from the APixaban for PRevention of Acute ISchemic Events 2 trial.

PubMed

Cornel, Jan H; Lopes, Renato D; James, Stefan; Stevens, Susanna R; Neely, Megan L; Liaw, Danny; Miller, Julie; Mohan, Puneet; Amerena, John; Raev, Dimitar; Huo, Yong; Urina-Triana, Miguel; Gallegos Cazorla, Alex; Vinereanu, Dragos; Fridrich, Viliam; Harrington, Robert A; Wallentin, Lars; Alexander, John H

2015-04-01

Clinical outcomes and the effects of oral anticoagulants among patients with acute coronary syndrome (ACS) and either a history of or acute heart failure (HF) are largely unknown. We aimed to assess the relationship between prior HF or acute HF complicating an index ACS event and subsequent clinical outcomes and the efficacy and safety of apixaban compared with placebo in these populations. High-risk patients were randomly assigned post-ACS to apixaban 5.0 mg or placebo twice daily. Median follow-up was 8 (4-12) months. The primary outcome was cardiovascular death, myocardial infarction, or stroke. The main safety outcome was thrombolysis in myocardial infarction major bleeding. Heart failure was reported in 2,995 patients (41%), either as prior HF (2,076 [28%]) or acute HF (2,028 [27%]). Patients with HF had a very high baseline risk and were more often managed medically. Heart failure was associated with a higher rate of the primary outcome (prior HF: adjusted hazard ratio [HR] 1.73, 95% CI 1.42-2.10, P < .0001, acute HF: adjusted HR 1.65, 95% CI 1.35-2.01, P < .0001) and cardiovascular death (prior HF: HR 2.54, 95% CI 1.82-3.54, acute HF: adjusted HR 2.52, 95% CI 1.82-3.50). Patients with acute HF also had significantly higher rates of thrombolysis in myocardial infarction major bleeding (prior HF: adjusted HR 1.22, 95% CI 0.65-2.27, P = .54, acute HF: adjusted HR 1.78, 95% CI 1.03-3.08, P = .04). There was no statistical evidence of a differential effect of apixaban on clinical events or bleeding in patients with or without prior HF; however, among patients with acute HF, there were numerically fewer events with apixaban than placebo (14.8 vs 19.3, HR 0.76, 95% CI 0.57-1.01, interaction P = .13), a trend that was not seen in patients with prior HF or no HF. In high-risk patients post-ACS, both prior and acute HFs are associated with an increased risk of subsequent clinical events. Apixaban did not significantly reduce clinical events and increased bleeding in patients with and without HF; however, there was a tendency toward fewer clinical events with apixaban in patients with acute HF. Copyright © 2015 Elsevier Inc. All rights reserved.

Determination of elemental carbon in lake sediments using a thermal-optical transmittance (TOT) method

NASA Astrophysics Data System (ADS)

Khan, A. J.; Swami, Kamal; Ahmed, Tanveer; Bari, A.; Shareef, Akhtar; Husain, Liaquat

2009-12-01

An improved chemical oxidation pretreatment method has been developed for the determination of elemental carbon (EC) [also known as black carbon (BC) or soot] in lake sediments, using a thermal-optical transmittance (TOT) carbon analyzer. The method employs six steps: (1) removal of carbonates by treatment with HCl; (2) removal of silicates by treatment with HF + HCl; (3) removal of any remaining carbonates by treatment with HCl; (4) removal of humic acids by treatment with NaOH; and (5) oxidation of kerogens by K 2Cr 2O 7 + H 2SO 4. A critical step of zinc chloride treatment was added; this apparently changes EC's morphology and enhances retention on quartz fiber filter, resulting in several-fold increased chemical yield. EC was determined using the TOT method with modified combustion timings. Carbon black (acetylene) and four NIST standard reference materials (SRMs) were used for quality control, and to assess the precision of the analysis. The EC recoveries from 18 carbon black samples varied from 90 to 111%, with a mean value of 99 ± 6%. The high EC recoveries confirmed the validity of the method. Char reference materials (i.e. chestnut wood and grass char) were used to determine potential contribution to EC in our measurements. The char references containing about 700 mg total organic carbon (OC) contributed ˜1.5% EC. The measured EC values from four NIST standards were 17.0 ± 0.6, 24.2 ± 3.2, 5.6, and 1.9 ± 0.1 mg g dw-1 for SRM-1648, SRM-1649a, SRM-1941b and SRM-8704, respectively. These values in SRMs were in agreement (<±4%) with the previously reported values. The method was applied to determine the EC in sediment cores from an urban lake and a remote mountain lake in the Northeastern United States. The EC concentrations in two lakes mimic the model EC emissions from the industrial revolution in United States.

Physical exercise counteracts the increase in velocity of propagation of cortical spreading depression imposed by early over-nutrition in rats.

PubMed

Monteiro, Heloísa Mirelle Costa; de Mendonça, Débora Carneiro; Sousa, Mariana Séfora Bezerra; Amancio-Dos-Santos, Angela

2018-06-01

This investigation studied whether physical exercise could modulate cortical spreading depression (CSD) propagation velocity in adult rat offspring from dams that had received a high-fat (HF) diet during lactation. Wistar male rats suckled by dams fed either control (C) or HF diet ad libitum. After weaning, pups received standard laboratory chow. From 40 to 60 days of life, half of the animals exercised on a treadmill (group E); the other half remained sedentary (group S). Two additional HF groups (E and S) received fluoxetine (F; 10 mg/kg/day, orogastrically) from 40 to 60 days of life (groups HF/EF and HF/F). At 40 days of life, rats from the maternal HF diet presented higher weight, thoracic circumference, and Lee Index than C animals and remained heavier at 60 days of life. Physical exercise decreased abdominal circumference. HF diet increased CSD propagation velocity (mean ± SD; mm/min) in sedentaries (HF/S 3.47 ± 0.31 versus C/S 3.24 ± 0.26). Treadmill exercise decelerated CSD propagation in both groups C/E (2.94 ± 0.28) and HF/E (2.97 ± 0.40). Fluoxetine alone decreased CSD propagation (HF/F 2.88 ± 0.45) compared with HF/S group. The combination of fluoxetine + exercise under HF condition (2.98 ± 0.27) was similar to HF/E group. Physical exercise is able to reduce CSD propagation velocity in rat adult brains even when they have suffered over-nourishing during lactation. The effects of exercise alone or fluoxetine alone on CSD were similar to the effects of fluoxetine + exercise, under the HF condition. Data reinforce malnutrition during lactation modifies cortical electrophysiology even when the HF condition no longer exists.

The effect of statin therapy on heart failure events: a collaborative meta-analysis of unpublished data from major randomized trials

PubMed Central

Preiss, David; Campbell, Ross T.; Murray, Heather M.; Ford, Ian; Packard, Chris J.; Sattar, Naveed; Rahimi, Kazem; Colhoun, Helen M.; Waters, David D.; LaRosa, John C.; Amarenco, Pierre; Pedersen, Terje R.; Tikkanen, Matti J.; Koren, Michael J.; Poulter, Neil R.; Sever, Peter S.; Ridker, Paul M.; MacFadyen, Jean G.; Solomon, Scott D.; Davis, Barry R.; Simpson, Lara M.; Nakamura, Haruo; Mizuno, Kyoichi; Marfisi, Rosa M.; Marchioli, Roberto; Tognoni, Gianni; Athyros, Vasilios G.; Ray, Kausik K.; Gotto, Antonio M.; Clearfield, Michael B.; Downs, John R.; McMurray, John J.

2015-01-01

Aims The effect of statins on risk of heart failure (HF) hospitalization and HF death remains uncertain. We aimed to establish whether statins reduce major HF events. Methods and results We searched Medline, EMBASE, and the Cochrane Central Register of Controlled Trials for randomized controlled endpoint statin trials from 1994 to 2014. Collaborating trialists provided unpublished data from adverse event reports. We included primary- and secondary-prevention statin trials with >1000 participants followed for >1 year. Outcomes consisted of first non-fatal HF hospitalization, HF death and a composite of first non-fatal HF hospitalization or HF death. HF events occurring <30 days after within-trial myocardial infarction (MI) were excluded. We calculated risk ratios (RR) with fixed-effects meta-analyses. In up to 17 trials with 132 538 participants conducted over 4.3 [weighted standard deviation (SD) 1.4] years, statin therapy reduced LDL-cholesterol by 0.97 mmol/L (weighted SD 0.38 mmol/L). Statins reduced the numbers of patients experiencing non-fatal HF hospitalization (1344/66 238 vs. 1498/66 330; RR 0.90, 95% confidence interval, CI 0.84–0.97) and the composite HF outcome (1234/57 734 vs. 1344/57 836; RR 0.92, 95% CI 0.85–0.99) but not HF death (213/57 734 vs. 220/57 836; RR 0.97, 95% CI 0.80–1.17). The effect of statins on first non-fatal HF hospitalization was similar whether this was preceded by MI (RR 0.87, 95% CI 0.68–1.11) or not (RR 0.91, 95% CI 0.84–0.98). Conclusion In primary- and secondary-prevention trials, statins modestly reduced the risks of non-fatal HF hospitalization and a composite of non-fatal HF hospitalization and HF death with no demonstrable difference in risk reduction between those who suffered an MI or not. PMID:25802390

Heart Failure Increases the Risk of Adverse Renal Outcomes in Patients With Normal Kidney Function.

PubMed

George, Lekha K; Koshy, Santhosh K G; Molnar, Miklos Z; Thomas, Fridtjof; Lu, Jun L; Kalantar-Zadeh, Kamyar; Kovesdy, Csaba P

2017-08-01

Heart failure (HF) is associated with poor cardiac outcomes and mortality. It is not known whether HF leads to poor renal outcomes in patients with normal kidney function. We hypothesized that HF is associated with worse long-term renal outcomes. Among 3 570 865 US veterans with estimated glomerular filtration rate (eGFR) ≥60 mL min -1 1.73 m -2 during October 1, 2004 to September 30, 2006, we identified 156 743 with an International Classification of Diseases , Ninth Revision , diagnosis of HF. We examined the association of HF with incident chronic kidney disease (CKD), the composite of incident CKD or mortality, and rapid rate of eGFR decline (slopes steeper than -5 mL min -1 1.73 m -2 y -1 ) using Cox proportional hazard analyses and logistic regression. Adjustments were made for various confounders. The mean±standard deviation baseline age and eGFR of HF patients were 68±11 years and 78±14 mL min -1 1.73 m -2 and in patients without HF were 59±14 years and 84±16 mL min -1 1.73 m -2 , respectively. HF patients had higher prevalence of hypertension, diabetes mellitus, cardiac, peripheral vascular and chronic lung diseases, stroke, and dementia. Incidence of CKD was 69.0/1000 patient-years in HF patients versus 14.5/1000 patient-years in patients without HF, and 22% of patients with HF had rapid decline in eGFR compared with 8.5% in patients without HF. HF patients had a 2.12-, 2.06-, and 2.13-fold higher multivariable-adjusted risk of incident CKD, composite of CKD or mortality, and rapid eGFR decline, respectively. HF is associated with significantly higher risk of incident CKD, incident CKD or mortality, and rapid eGFR decline. Early diagnosis and management of HF could help reduce the risk of long-term renal complications. © 2017 American Heart Association, Inc.

A Consistency Evaluation and Calibration Method for Piezoelectric Transmitters.

PubMed

Zhang, Kai; Tan, Baohai; Liu, Xianping

2017-04-28

Array transducer and transducer combination technologies are evolving rapidly. While adapting transmitter combination technologies, the parameter consistencies between each transmitter are extremely important because they can determine a combined effort directly. This study presents a consistency evaluation and calibration method for piezoelectric transmitters by using impedance analyzers. Firstly, electronic parameters of transmitters that can be measured by impedance analyzers are introduced. A variety of transmitter acoustic energies that are caused by these parameter differences are then analyzed and certified and, thereafter, transmitter consistency is evaluated. Lastly, based on the evaluations, consistency can be calibrated by changing the corresponding excitation voltage. Acoustic experiments show that this method accurately evaluates and calibrates transducer consistencies, and is easy to realize.

Effects of harness-attached transmitters on premigration and reproduction of Brant

USGS Publications Warehouse

Ward, David H.; Flint, Paul L.

1995-01-01

Radio transmitters are an important tool in waterfowl ecology studies, but little is known about their effects on free-ranging geese. We attached transmitters to female brant (Branta bernicla nigricans) to investigate migration schedules at a fall staging area, return rates to nesting grounds, and nesting rates of returning females in subsequent breeding seasons. Radio-tagged females (n = 62) carried either 35-g back-mounted transmitters attached with ribbon harnesses, or 26- or 32-g back-mounted transmitters affixed with plastic-coated wire harnesses (Dwyer 1972). Arrival and departure schedules at Izembek Lagoon, Alaska, did not differ (P > 0.05) between radio-tagged females and the entire population in 1987-89. Color-banded females with transmitters returned to the breeding colony in subsequent nesting seasons (1988-92) at a lower (P ≤ 0.003) rate (≤4%) than color-banded females without transmitters (57-83%). The 1 returning color-banded female with a transmitter did not breed, while an average 90% of the returning color-banded females without transmitters nested in subsequent breeding seasons (P = 0.005). Back-mounted, harness-attached transmitters may bias data in studies of waterfowl behavior, productivity, and survival.

Influence of LVAD function on mechanical unloading and electromechanical delay: a simulation study.

PubMed

Heikhmakhtiar, Aulia Khamas; Ryu, Ah Jin; Shim, Eun Bo; Song, Kwang-Soup; Trayanova, Natalia A; Lim, Ki Moo

2018-05-01

This study hypothesized that a left ventricular assist device (LVAD) shortens the electromechanical delay (EMD) by mechanical unloading. The goal of this study is to examine, by computational modeling, the influence of LVAD on EMD for four heart failure (HF) cases ranging from mild HF to severe HF. We constructed an integrated model of an LVAD-implanted cardiovascular system, then we altered the Ca 2+ transient magnitude, with scaling factors 1, 0.9, 0.8, and 0.7 representing HF1, HF2, HF3, and HF4, respectively, in order of increasing HF severity. The four HF conditions are classified into two groups. Group one is the four HF conditions without LVAD, and group two is the conditions treated with continuous LVAD pump. The single-cell mechanical responses showed that EMD was prolonged with the higher load. The findings indicated that in group one, the HF-induced Ca2 + transient remodeling prolonged the mechanical activation time (MAT) and decreased the contractile tension, which reduced the left ventricle (LV) pressure, and increased the end-diastolic strain. In group two, LVAD shortened MAT of the ventricles. Furthermore, LVAD reduced the contractile tension, and end-diastolic strain, but increased the aortic pressure. The computational study demonstrated that LVAD shortens EMD by mechanical unloading of the ventricle.

LU-HF Age and Isotope Systematics of ALH84001

NASA Technical Reports Server (NTRS)

Righter, M.; Lapen, T. J.; Brandon, A. D.; Beard, B. L.; Shafer, J. T.; Peslier, A. H.

2009-01-01

Allan Hills (ALH) 84001 is an orthopyroxenite that is unique among the Martian meteorites in having the oldest inferred crystallization age (approx..4.5 to 4.0 Gyr) [e.g., 1-6 and references therein 7]. Its ancient origin makes this stone a critical constraint on early history of Mars, in particular the evolution of different planetary crust and mantle reservoirs. However, because there is significant variability in reported crystallization ages, determination of initial isotope compositions is imprecise making assessment of planetary reservoirs difficult. Here we report a new Lu-Hf mineral isochron age, initial Hf-176/Hf-177 isotope composition, and inferred Martian mantle source compositions for ALH84001 that place constraints on longlived source reservoirs for the enriched shergottite suite of Martian meteorites including Shergotty, Zagami, NWA4468, NWA856, RBT04262, LAR06319, and Los Angeles. Sm-Nd isotope analyses are under way for the same mineral aliquots analyzed for Lu-Hf. The Lu-Hf system was utilized because Lu and Hf are both lithophile and refractory and are not easily redistributed during short-lived thermal pulses associated with shock metamorphism. Moreover, chromite has relatively modest Hf concentrations with very low Lu/Hf ratios [9] yielding tight constraints on initial Hf-176/Hf-177 isotope compositions

Evolution of the mechanical and tribological properties of DLC thin films doped with low-concentration hafnium on 316L steel

NASA Astrophysics Data System (ADS)

Qi, Meng; Xiao, Jianrong; Gong, Chenyang; Jiang, Aihua; Chen, Yong

2018-01-01

Low concentrations (<1 at%) of hafnium doped into diamond-like thin films (Hf-DLC) were deposited on 316L stainless steel and silicon (1 0 0) substrates by magnetron sputtering to attain superior mechanical and tribological properties. Ar and CH4 were used as source gases. The microstructure, chemical composition, and morphology of the Hf-DLC thin films in various concentrations were analyzed using x-ray diffraction, Raman spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Results showed that Hf species transferred from the particulate microstructure to Hf carbide phases, and the surface roughness increased monotonically with increasing Hf concentration. Moreover, the hardness and elastic modulus exhibited high values when the doped Hf concentration was 0.42 at%. Similarly, the tribological behaviors and wear life of Hf-DLC thin films had a low friction coefficient and excellent wear resistance at 0.42 at% Hf concentration. Therefore, 0.42 at% Hf is an optimal doping concentration to improve the mechanical and tribological properties of DLC thin films. Generally, the use of low-concentration Hf doping into DLC thin films is novel, and the present results provide guidance for the selection of suitable and effective concentration to optimize Hf-DLC thin films with superior performance.

Meditation-induced changes in high-frequency heart rate variability predict smoking outcomes

PubMed Central

Libby, Daniel J.; Worhunsky, Patrick D.; Pilver, Corey E.; Brewer, Judson A.

2012-01-01

Background: High-frequency heart rate variability (HF-HRV) is a measure of parasympathetic nervous system (PNS) output that has been associated with enhanced self-regulation. Low resting levels of HF-HRV are associated with nicotine dependence and blunted stress-related changes in HF-HRV are associated with decreased ability to resist smoking. Meditation has been shown to increase HF-HRV. However, it is unknown whether tonic levels of HF-HRV or acute changes in HF-HRV during meditation predict treatment responses in addictive behaviors such as smoking cessation. Purpose: To investigate the relationship between HF-HRV and subsequent smoking outcomes. Methods: HF-HRV during resting baseline and during mindfulness meditation was measured within two weeks of completing a 4-week smoking cessation intervention in a sample of 31 community participants. Self-report measures of smoking were obtained at a follow up 17-weeks after the initiation of treatment. Results: Regression analyses indicated that individuals exhibiting acute increases in HF-HRV from resting baseline to meditation smoked fewer cigarettes at follow-up than those who exhibited acute decreases in HF-HRV (b = −4.89, p = 0.008). Conclusion: Acute changes in HF-HRV in response to meditation may be a useful tool to predict smoking cessation treatment response. PMID:22457646

Prognostic significance of anaemia in patients with heart failure with preserved and reduced ejection fraction: results from the MAGGIC individual patient data meta-analysis.

PubMed

Berry, C; Poppe, K K; Gamble, G D; Earle, N J; Ezekowitz, J A; Squire, I B; McMurray, J J V; McAlister, F A; Komajda, M; Swedberg, K; Maggioni, A P; Ahmed, A; Whalley, G A; Doughty, R N; Tarantini, L

2016-06-01

Anaemia is common among patients with heart failure (HF) and is an important prognostic marker. We sought to determine the prognostic importance of anaemia in a large multinational pooled dataset of prospectively enrolled HF patients, with the specific aim to determine the prognostic role of anaemia in HF with preserved and reduced ejection fraction (HF-PEF and HF-REF, respectively). Individual person data meta-analysis. Patients with haemoglobin (Hb) data from the MAGGIC dataset were used. Anaemia was defined as Hb < 120 g/l in women and <130 g/l in men. HF-PEF was defined as EF ≥ 50%; HF-REF was EF < 50%. Cox proportional hazard modelling, with adjustment for clinically relevant variables, was undertaken to investigate factors associated with 3-year all-cause mortality. Thirteen thousand two hundred and ninety-five patients with HF from 19 studies (9887 with HF-REF and 3408 with HF-PEF). The prevalence of anaemia was similar among those with HF-REF and HF-PEF (42.8 and 41.6% respectively). Compared with patients with normal Hb values, those with anaemia were older, were more likely to have diabetes, ischaemic aetiology, New York Heart Association class IV symptoms, lower estimated glomerular filtration rate and were more likely to be taking diuretic and less likely to be taking a beta-blocker. Patients with anaemia had higher all-cause mortality (adjusted hazard ratio [aHR] 1.38, 95% confidence interval [CI] 1.25-1.51), independent of EF group: aHR 1.67 (1.39-1.99) in HF-PEF and aHR 2.49 (2.13-2.90) in HF-REF. Anaemia is an adverse prognostic factor in HF irrespective of EF. The prognostic importance of anaemia was greatest in patients with HF-REF. © The Author 2015. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Modulation of hepatic stellate cells and reversibility of hepatic fibrosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yu, E-mail: 1293363632@QQ.com; Deng, Xin, E-mail: Hendly@163.com; Liang, Jian, E-mail: lj99669@163.com

Hepatic fibrosis (HF) is the pathological component of a variety of chronic liver diseases. Hepatic stellate cells (HSC) are the main collagen-producing cells in the liver and their activation promotes HF. If HSC activation and proliferation can be inhibited, HF occurrence and development can theoretically be reduced and even reversed. Over the past ten years, a number of studies have addressed this process, and here we present a review of HSC modulation and HF reversal. - Highlights: • We present a review of the modulation of hepatic stellate cells (HSC) and reversibility of hepatic fibrosis (HF). • HSC are themore » foci of HF occurrence and development, HF could be prevented and treated by modulating HSC. • If HSC activation and proliferation can be inhibited, HF could theoretically be inhibited and even reversed. • Prevention or reversal of HSC activation, or promotion of HSC apoptosis, immune elimination, and senescence may prevent, inhibit or reverse HF.« less

Hafnium Isotopic Variations in Central Atlantic Intraplate Volcanism

NASA Astrophysics Data System (ADS)

Geldmacher, J.; Hanan, B. B.; Hoernle, K.; Blichert-Toft, J.

2008-12-01

Although one of the geochemically best investigated volcanic regions on Earth, almost no Hf isotopic data have been published from the broad belt of intraplate seamounts and islands in the East Atlantic between 25° and 36° N. This study presents 176Hf/177Hf ratios from 61 representative samples from the Canary, Selvagen and Madeira Islands and nearby large seamounts, encompassing the full range of different evolutionary stages and geochemical endmembers. The majority of samples have mafic, mainly basaltic compositions with Mg-numbers within or near the range of magmas in equilibrium with mantle olivine (68-75). No correlation was found between Mg-number and 176Hf/177Hf ratios in the data set. In comparison to observed Nd isotope variations published for this volcanic province (6 ɛNd units), 176Hf/177Hf ratios span a larger range (14 ɛHf units). Samples from the Madeira archipelago have the most radiogenic compositions (176Hf/177Hfm= 0.283132-0.283335), widely overlapping the field for central Atlantic N-MORB. They form a relatively narrow, elongated trend (stretching over >6 ɛHf units) between a radiogenic MORB-like endmember and a composition located on the Nd-Hf mantle array. In contrast, all Canary Islands samples plot below the mantle array (176Hf/177Hfm = 0.282943-0.283067) and, despite being from an archipelago that stretches over a much larger geographic area, form a much denser cluster with less compositional variation (~4 ɛHf units). All samples from the seamounts NE of the Canaries, proposed to belong to the same Canary hotspot track (e.g. Geldmacher et al., 2001, JVGR 111; Geldmacher et al., 2005, EPSL 237), fall within the Hf isotopic range of this cluster. The cluster largely overlaps the composition of the proposed common mantle endmember 'C' (Hanan and Graham, 1996, Science 272) but spans a space between a more radiogenic (depleted) composition and a HIMU-type endmember. Although samples of Seine and Unicorn seamounts, attributed to the Madeira hotspot track, show less radiogenic Hf and Nd isotope ratios than Madeira, their isotopic compositions lie along an extension of the Madeira trend in plots of Hf versus Sr, Nd, Pb isotopes. The new Hf isotope ratios confirm the existence of at least two geochemically distinct volcanic provinces (Canary and Madeira) in the East Atlantic as previously proposed.

Lu-Hf and Sm-Nd isotope systematics of Korean spinel peridotites: A case for metasomatically induced Nd-Hf decoupling

NASA Astrophysics Data System (ADS)

Choi, Sung Hi; Mukasa, Samuel B.

2012-12-01

We determined the Lu-Hf and Sm-Nd isotope compositions of spinel peridotite xenoliths in alkali basalts from Baengnyeong and Jeju islands, South Korea, to constrain the timing of melt-depletion events and stabilization of the lithospheric mantle beneath the region. Equilibration temperatures estimated by two-pyroxene thermometry range from 780 to 950 °C, and from 960 to 1010 °C for Baengnyeong and Jeju peridotites, respectively. The Baengnyeong peridotite clinopyroxenes are characterized by extremely radiogenic Hf in association with isotopically less extreme Nd, resulting in strong Nd-Hf decoupling referenced to the mantle array. This is in stark contrast to the well-correlated isotopic compositions of Hf and Nd in the Jeju peridotite clinopyroxenes, which plot along the Nd-Hf mantle array. The Hf abundances and isotopic compositions of the Baengnyeong clinopyroxenes were less affected by relatively recent secondary enrichments that overprinted the light rare earth element abundances and Nd isotopes, causing the decoupling of the Nd-Hf isotopes. The Nd-Hf isotopic compositions of the Jeju peridotites appear to have been re-equilibrated, probably as a result of efficient diffusion at the relatively higher temperatures of the Jeju peridotites. Lu-Hf tie lines for clinopyroxene and orthopyroxene from four of the Korean peridotites have negative slopes on a Lu-Hf isochron diagram, yielding negative ages. This is interpreted to indicate recent isotopic exchange in orthopyroxene by reaction with metasomatic agents having low 176Hf/177Hf components. Secondary overprinting in orthopyroxene was facilitated by the considerably lower Hf concentrations than in co-located clinopyroxene. Baengnyeong lherzolite clinopyroxenes yield a Lu-Hf errorchron age of 1.9 ± 0.1 Ga, which is independently supported by a model Os age (based on Re depletion or TRD) of 1.8 Ga on a refractory Baengnyeong peridotite. We interpret this age range to mark the time of stabilization of the mantle section beneath this area by major melt extraction. This Proterozoic melt removal coincided in time with widespread ca. 2.1 to 1.8 Ga tectonothermal events documented throughout the Korean Peninsula. These observations indicate that the Lu-Hf system can be used to date mantle melting events recorded in lherzolite xenoliths.

Lu-Hf and Sm-Nd isotope systematics of Korean spinel peridotites: A case for metasomatically induced Nd-Hf decoupling

NASA Astrophysics Data System (ADS)

Choi, S.; Mukasa, S. B.

2012-12-01

We determined the Lu-Hf and Sm-Nd isotope compositions of spinel peridotite xenoliths in alkali basalts from Baengnyeong and Jeju islands, South Korea, to constrain the timing of melt-depletion events and stabilization of the lithospheric mantle beneath the region. Equilibration temperatures estimated by two-pyroxene thermometry range from 780 to 950°C, and from 960 to 1010°C for Baengnyeong and Jeju peridotites, respectively. The Baengnyeong peridotite clinopyroxenes are characterized by extremely radiogenic Hf in association with isotopically less extreme Nd, resulting in strong Nd-Hf decoupling referenced to the mantle array. This is in stark contrast to the well-correlated isotopic compositions of Hf and Nd in the Jeju peridotite clinopyroxenes, which plot along the Nd-Hf mantle array. The Hf abundances and isotopic compositions of the Baengnyeong clinopyroxenes were less affected by relatively recent secondary enrichments that overprinted the light rare earth element abundances and Nd isotopes, causing the decoupling of the Nd-Hf isotopes. The Nd-Hf isotopic compositions of the Jeju peridotites appear to have been re-equilibrated, probably as a result of efficient diffusion at the relatively higher temperatures of the Jeju peridotites. Lu-Hf tie lines for clinopyroxene and orthopyroxene from four of the Korean peridotites have negative slopes on a Lu-Hf isochron diagram, yielding negative ages. This is interpreted to indicate recent isotopic exchange in orthopyroxene by reaction with metasomatic agents having low 176Hf/177Hf components. Secondary overprinting in orthopyroxene was facilitated by the considerably lower Hf concentrations than in co-located clinopyroxene. Baengnyeong lherzolite clinopyroxenes yield a Lu-Hf errorchron age of 1.9 ± 0.1 Ga, which is independently supported by a model Os age (based on Re depletion or TRD) of 1.8 Ga on a refractory Baengnyeong peridotite. We interpret this age range to mark the time of stabilization of the mantle section beneath this area by major melt extraction. This Proterozoic melt removal coincided in time with widespread ca. 2.1 to 1.8 Ga tectonothermal events documented throughout the Korean Peninsula. These observations indicate that the Lu-Hf system can be used to date mantle melting events recorded in lherzolite xenoliths.

Modified method for external attachment of transmitters to birds using two subcutaneous anchors

USGS Publications Warehouse

Lewis, T.L.; Flint, Paul L.

2008-01-01

Of the transmitter attachment techniques for birds, the subcutaneous anchor provides a secure attachment that yields relatively few secondary effects. However, the use of subcutaneous anchors has been limited by transmitter size and retention time. Using a modified method of attachment that utilized two subcutaneous anchors, we deployed 69 GPS transmitters, plus 13 VHF transmitters that were similar in size and weight to GPS models, on Pacific Black Brant (Branta bernicla nigricans). Prior to our study, only harnesses were used for attaching GPS transmitters on birds, mainly because GPS transmitters are too large for other external attachment techniques and implantation in the body cavity attenuates the GPS signal. Thus, to increase the size capacity of anchor attachment and to avoid the well-documented negative effects of harnesses on behavior and survival, we added a second anchor at the transmitter's posterior end. The double-anchor attachment technique was quickly and easily accomplished in the field, requiring bird handling times of <10 min. Incidental recoveries of tagged Brant indicate a high degree of transmitter retention. Five recaptured birds (4-6 weeks after deployment) and eight killed by hunters (3-6 mo after deployment) retained their GPS transmitters. For studies involving the use of relatively large transmitters, the double-anchor method appears to provide a viable alternative for external attachment. ?? 2008 Association of Field Ornithologists.

Lu-Hf and Sm-Nd Isotopic Studies of Shergottites and Nakhlites: Implications for Martian Mantle Sources

NASA Technical Reports Server (NTRS)

Debaille, V.; Yin, Q.-Z.; Brandon, A. D.; Jacobsen, B.; Treiman, A. H.

2007-01-01

We present a new Lu-Hf and Sm-Nd isotope systematics study of four enriched shergottites (Zagami, Shergotty, NWA856 and Los Angeles), and three nakhlites (Nakhla, MIL03346 and Yamato 000593) in order to further understand processes occurring during the early differentiation of Mars and the crystallization of its magma ocean. Two fractions of the terrestrial petrological analogue of nakhlites, the Archaean Theo's flow (Ontario, Canada) were also measured. The coupling of Nd and Hf isotopes provide direct insights on the mineralogy of the melt sources. In contrast to Sm/Nd, Lu/Hf ratios can be very large in minerals such as garnet. Selective partial melting of garnet bearing mantle sources can therefore lead to characteristic Lu/Hf signatures that can be recognized with Hf-176/Hf-177Hf ratios.

Sleep Disordered Breathing in Heart Failure: Identifying and Treating an Important but Often Unrecognized Comorbidity in Heart Failure Patients

PubMed Central

Khayat, Rami; Small, Roy; Rathman, Lisa; Krueger, Steven; Gocke, Becky; Clark, Linda; Yamokoski, Laura; Abraham, William T.

2013-01-01

Sleep disordered breathing (SDB) is the most common co-morbidity in patients with heart failure (HF) and has a significant impact on quality of life, morbidity, and mortality. A number of therapeutic options have become available in recent years that can improve quality of life and potentially the outcomes of HF patients with SDB. Unfortunately, SDB is not part of the routine evaluation and management of HF, thus it remains untreated in most HF patients. While recognition of the role of SDB in HF is increasing, clinical guidelines for the management of SDB in HF patients continue to be absent. In this article we provide an overview of SDB in HF and propose a clinical care pathway to help clinicians better recognize and treat SDB in their HF patients. PMID:23743494

Do Hf isotopes in magmatic zircons represent those of their host rocks?

NASA Astrophysics Data System (ADS)

Wang, Di; Wang, Xiao-Lei; Cai, Yue; Goldstein, Steven L.; Yang, Tao

2018-04-01

Lu-Hf isotopic system in zircon is a powerful and widely used geochemical tracer in studying petrogenesis of magmatic rocks and crustal evolution, assuming that zircon Hf isotopes can represent initial Hf isotopes of their parental whole rock. However, this assumption may not always be valid. Disequilibrium partial melting of continental crust would preferentially melt out non-zircon minerals with high time-integrated Lu/Hf ratios and generate partial melts with Hf isotope compositions that are more radiogenic than those of its magma source. Dissolution experiments (with hotplate, bomb and sintering procedures) of zircon-bearing samples demonstrate this disequilibrium effect where partial dissolution yielded variable and more radiogenic Hf isotope compositions than fully dissolved samples. A case study from the Neoproterozoic Jiuling batholith in southern China shows that about half of the investigated samples show decoupled Hf isotopes between zircons and the bulk rocks. This decoupling could reflect complex and prolonged magmatic processes, such as crustal assimilation, magma mixing, and disequilibrium melting, which are consistent with the wide temperature spectrum from ∼630 °C to ∼900 °C by Ti-in-zircon thermometer. We suggest that magmatic zircons may only record the Hf isotopic composition of their surrounding melt during crystallization and it is uncertain whether their Hf isotopic compositions can represent the primary Hf isotopic compositions of the bulk magmas. In this regard, using zircon Hf isotopic compositions to trace crustal evolution may be biased since most of these could be originally from disequilibrium partial melts.

Ab initio theoretical study of dipole-bound anions of molecular complexes: (HF)3- and (HF)4- anions

NASA Astrophysics Data System (ADS)

Ramaekers, Riet; Smith, Dayle M. A.; Smets, Johan; Adamowicz, Ludwik

1997-12-01

Ab initio calculations have been performed to determine structures and vertical electron detachment energy (VDE) of the hydrogen fluoride trimer and tetramer anions, (HF)3- and (HF)4-. In these systems the excess electron is bound by the dipole field of the complex. It was determined that, unlike the neutral complexes which prefer the cyclic structures, the equilibrium geometries of the anions have "zig-zag" shapes. For both complexes the predicted VDEs are positive [210 meV and 363 meV for (HF)3- and (HF)4-, respectively], indicating that the anions are stable systems with respect to the vertical electron detachment. These results were obtained at the coupled-cluster level of theory with single, double and triple excitations [CCSD(T) method; the triple-excitation contribution in this method is calculated approximately using the perturbation approach] with the anion geometries obtained using the second-order Møller-Plesset perturbation theory (MP2) method. The same approach was also used to determine the adiabatic electron affinities (AEA) of (HF)3 and (HF)4. In addition to the electronic contribution, we also calculated the contributions (using the harmonic approximation) resulting from different zero-point vibration energies of the neutral and anionic clusters. The calculations predicted that while the AEA of (HF)3 is positive (44 meV), the AEA for (HF)4 is marginally negative (-16 meV). This suggests that the (HF)3- anion should be a stable system, while the (HF)4- is probably metastable.

Educational needs for improving self-care in heart failure patients with diabetes.

PubMed

Cha, EunSeok; Clark, Patricia C; Reilly, Carolyn Miller; Higgins, Melinda; Lobb, Maureen; Smith, Andrew L; Dunbar, Sandra B

2012-01-01

To explore the need for self-monitoring and self-care education in heart failure patients with diabetes (HF- DM patients) by describing cognitive and affective factors to provide guidance in developing effective self-management education. A cross-sectional correlation design was employed using baseline patient data from a study testing a 12-week patient and family dyad intervention to improve dietary and medication-taking self-management behaviors in HF patients. Data from 116 participants recruited from metropolitan Atlanta area were used. Demographic and comorbidities, physical function, psychological distress, relationship with health care provider, self-efficacy (medication taking and low sodium diet), and behavioral outcomes (medications, dietary habits) were assessed. Descriptive statistics and a series of chi-square tests, t tests, or Mann-Whitney tests were performed to compare HF patients with and without DM. HF-DM patients were older and heavier, had more comorbidities, and took more daily medications than HF patients. High self-efficacy on medication and low-sodium diet was reported in both groups with no significant difference. Although HF-DM patients took more daily medications than HF, both groups exhibited high HF medication-taking behaviors. The HF-DM patients consumed significantly lower total sugar than HF patients but clinically higher levels of sodium. Diabetes educators need to be aware of potential conflicts of treatment regimens to manage 2 chronic diseases. Special and integrated diabetes self-management education programs that incorporate principles of HF self-management should be developed to improve self-management behavior in HF-DM patients.

A Low Cost TDRSS Compatible Transmitter Option

NASA Technical Reports Server (NTRS)

Whiteman, Don

2005-01-01

The NASA Space-based Telemetry and Range Safety (STARS) program has developed and tested a low cost Ku-Band transmitter alternative for TDRSS applications based on an existing IRIG shaped offset quaternary phase shift keying (SOQPSK) transmitter. This paper presents information related to the implementation of this low cost system, as well as performance measurements of the alternative TDRSS transmitter system compared with an existing QPSK TDRSS transmitter.

Nature, nurture or nutrition? Impact of maternal nutrition on maternal care, offspring development and reproductive function

PubMed Central

Connor, K L; Vickers, M H; Beltrand, J; Meaney, M J; Sloboda, D M

2012-01-01

We have previously reported that offspring of mothers fed a high fat (HF) diet during pregnancy and lactation enter puberty early and are hyperleptinaemic, hyperinsulinaemic and obese as adults. Poor maternal care and bonding can also impact offspring development and disease risk. We therefore hypothesized that prenatal nutrition would affect maternal care and that an interaction may exist between a maternal HF diet and maternal care, subsequently impacting on offspring phenotype. Wistar rats were mated and randomized to control dams fed a control diet (CON) or dams fed a HF diet from conception until the end of lactation (HF). Maternal care was assessed by observing maternal licking and grooming of pups between postnatal day (P)3 and P8. Postweaning (P22), offspring were fed a control (–con) or HF (–hf) diet. From P27, pubertal onset was assessed. At ∼P105 oestrous cyclicity was investigated. Maternal HF diet reduced maternal care; HF-fed mothers licked and groomed pups less than CON dams. Maternal fat:lean ratio was higher in HF dams at weaning and was associated with higher maternal plasma leptin and insulin concentrations, but there was no effect of maternal care on fat:lean ratio or maternal hormone levels. Both female and male offspring of HF dams were lighter from birth to P11 than offspring of CON dams, but by P19, HF offspring were heavier than controls. Prepubertal retroperitoneal fat mass was greater in pups from HF-fed dams compared to CON and was associated with elevated circulating leptin concentrations in females only, but there was neither an effect of maternal care, nor an interaction between maternal diet and care on prepubertal fat mass. Pups from HF-fed dams went into puberty early and this effect was exacerbated by a postweaning HF diet. Maternal and postweaning HF diets independently altered oestrous cyclicity in females: female offspring of HF-fed mothers were more likely to have prolonged or persistent oestrus, whilst female offspring fed a HF diet postweaning were more likely to have irregular oestrous cycles and were more likely to have prolonged or persistent oestrus. These data indicate that maternal HF nutrition during pregnancy and lactation results in a maternal obese phenotype and has significant impact on maternal care during lactation. Maternal and postweaning nutritional signals, independent of maternal care, alter offspring body fat pre-puberty and female reproductive function in adulthood, which may be associated with advanced ovarian ageing and altered fertility. PMID:22411006

Genetics of common forms of heart failure: challenges and potential solutions.

PubMed

Rau, Christoph D; Lusis, Aldons J; Wang, Yibin

2015-05-01

In contrast to many other human diseases, the use of genome-wide association studies (GWAS) to identify genes for heart failure (HF) has had limited success. We will discuss the underlying challenges as well as potential new approaches to understanding the genetics of common forms of HF. Recent research using intermediate phenotypes, more detailed and quantitative stratification of HF symptoms, founder populations and novel animal models has begun to allow researchers to make headway toward explaining the genetics underlying HF using GWAS techniques. By expanding analyses of HF to improved clinical traits, additional HF classifications and innovative model systems, the intractability of human HF GWAS should be ameliorated significantly.

Hf thickness dependence of spin-orbit torques in Hf/CoFeB/MgO heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramaswamy, Rajagopalan; Qiu, Xuepeng; Dutta, Tanmay

We have studied the spin-orbit torques in perpendicularly magnetized Hf/CoFeB/MgO system, by systematically varying the thickness of Hf underlayer. We have observed a sign change of effective fields between Hf thicknesses of 1.75 and 2 nm, indicating that competing mechanisms, such as the Rashba and spin Hall effects, contribute to spin-orbit torques in our system. For larger Hf thicknesses (>2 nm), both the components of spin-orbit torques arise predominantly from the bulk spin Hall effect. We have also confirmed these results using spin-orbit torque induced magnetization switching measurements. Our results could be helpful in designing Hf based SOT devices.

Vibration-Rotation Bands of HF and DF

DTIC Science & Technology

1977-09-23

98 IZa. Comparison of Observed and Calculated Line Positions of HF, Av = I Sequence ........................... 99 f2b. Comparison of Observed and...Calculated Line Positions of HF, Av = 2 Sequence ........................... 102 12c. Comparison of Observed and Calculated Line Positions of HF, Av = 3...Sequence ........................... 107 i2d. Comparison of Observed and Calculated Line Positions ofHF, Av = 4 Sequence ........................... fi

[Complementary treatment of acute heart failure in patients with diabetes, chronic obstructive pulmonary disease or anemia].

PubMed

Carrasco Sánchez, Francisco Javier; Recio Iglesias, Jesús; Grau Amorós, Jordi

2014-03-01

Diabetes, chronic obstructive pulmonary disease (COPD) and anemia are comorbidities with a high prevalence and impact in heart failure (HF). The presence of these comorbidities considerably worsens the prognosis of HF. Diabetic patients have a higher likelihood of developing symptoms of HF and both the treatment of diabetes and that of acute HF are altered by the coexistence of both entities. The glycemic targets in patients with acute HF are not well-defined, but could show a U-shaped relationship. Stress hyperglycemia in non-diabetic patients with HF could also have a deleterious effect on the medium-term prognosis. The inter-relationship between COPD and HF hampers diagnosis due to the overlap between the symptoms and signs of both entities and complementary investigations. The treatment of acute HF is also altered by the presence of COPD. Anemia is highly prevalent and is often the direct cause of decompensated HF, the most common cause being iron deficiency anemia. Iron replacement therapy, specifically intravenous forms, has helped to improve the prognosis of acute HF. Copyright © 2014 Elsevier España, S.L. All rights reserved.

The Juvenile Hafnium Isotope Signal as a Record of Supercontinent Cycles.

PubMed

Gardiner, Nicholas J; Kirkland, Christopher L; Van Kranendonk, Martin J

2016-12-07

Hf isotope ratios measured in igneous zircon are controlled by magmatic source, which may be linked to tectonic setting. Over the 200-500 Myr periodicity of the supercontinent cycle - the principal geological phenomenon controlling prevailing global tectonic style - juvenile Hf signals, i.e. most radiogenic, are typically measured in zircon from granites formed in arc settings (crustal growth), and evolved zircon Hf signals in granites formed in continent-collision settings (crustal reworking). Interrogations of Hf datasets for excursions related to Earth events commonly use the median value, however this may be equivocal due to magma mixing. The most juvenile part of the Hf signal is less influenced by crustal in-mixing, and arguably a more sensitive archive of Earth's geodynamic state. We analyze the global Hf dataset for this juvenile signal, statistically correlating supercontinent amalgamation intervals with evolved Hf episodes, and breakup leading to re-assembly with juvenile Hf episodes. The juvenile Hf signal is more sensitive to Pangaea and Rodinia assembly, its amplitude increasing with successive cycles to a maximum with Gondwana assembly which may reflect enhanced subduction-erosion. We demonstrate that the juvenile Hf signal carries important information on prevailing global magmatic style, and thus tectonic processes.

The Juvenile Hafnium Isotope Signal as a Record of Supercontinent Cycles

NASA Astrophysics Data System (ADS)

Gardiner, Nicholas J.; Kirkland, Christopher L.; van Kranendonk, Martin J.

2016-12-01

Hf isotope ratios measured in igneous zircon are controlled by magmatic source, which may be linked to tectonic setting. Over the 200-500 Myr periodicity of the supercontinent cycle - the principal geological phenomenon controlling prevailing global tectonic style - juvenile Hf signals, i.e. most radiogenic, are typically measured in zircon from granites formed in arc settings (crustal growth), and evolved zircon Hf signals in granites formed in continent-collision settings (crustal reworking). Interrogations of Hf datasets for excursions related to Earth events commonly use the median value, however this may be equivocal due to magma mixing. The most juvenile part of the Hf signal is less influenced by crustal in-mixing, and arguably a more sensitive archive of Earth’s geodynamic state. We analyze the global Hf dataset for this juvenile signal, statistically correlating supercontinent amalgamation intervals with evolved Hf episodes, and breakup leading to re-assembly with juvenile Hf episodes. The juvenile Hf signal is more sensitive to Pangaea and Rodinia assembly, its amplitude increasing with successive cycles to a maximum with Gondwana assembly which may reflect enhanced subduction-erosion. We demonstrate that the juvenile Hf signal carries important information on prevailing global magmatic style, and thus tectonic processes.

Interfacial structure and electrical properties of ultrathin HfO2 dielectric films on Si substrates by surface sol-gel method

NASA Astrophysics Data System (ADS)

Gong, You-Pin; Li, Ai-Dong; Qian, Xu; Zhao, Chao; Wu, Di

2009-01-01

Ultrathin HfO2 films with about ~3 nm thickness were deposited on n-type (1 0 0) silicon substrates using hafnium chloride (HfCl4) source by the surface sol-gel method and post-deposition annealing (PDA). The interfacial structure and electrical properties of ultrathin HfO2 films were investigated. The HfO2 films show amorphous structures and smooth surface morphologies with a very thin interfacial oxide layer of ~0.5 nm and small surface roughness (~0.45 nm). The 500 °C PDA treatment forms stronger Hf-O bonds, leading to passivated traps, and the interfacial layer is mainly Hf silicate (HfxSiyOz). Equivalent oxide thickness of around 0.84 nm of HfO2/Si has been obtained with a leakage current density of 0.7 A cm-2 at Vfb + 1 V after 500 °C PDA. It was found that the current conduction mechanism of HfO2/Si varied from Schottky-Richardson emission to Fowler-Nordheim tunnelling at an applied higher positive voltage due to the activated partial traps remaining in the ultrathin HfO2 films.

Study of Direct-Contact HfO2/Si Interfaces

PubMed Central

Miyata, Noriyuki

2012-01-01

Controlling monolayer Si oxide at the HfO2/Si interface is a challenging issue in scaling the equivalent oxide thickness of HfO2/Si gate stack structures. A concept that the author proposes to control the Si oxide interface by using ultra-high vacuum electron-beam HfO2 deposition is described in this review paper, which enables the so-called direct-contact HfO2/Si structures to be prepared. The electrical characteristics of the HfO2/Si metal-oxide-semiconductor capacitors are reviewed, which suggest a sufficiently low interface state density for the operation of metal-oxide-semiconductor field-effect-transistors (MOSFETs) but reveal the formation of an unexpected strong interface dipole. Kelvin probe measurements of the HfO2/Si structures provide obvious evidence for the formation of dipoles at the HfO2/Si interfaces. The author proposes that one-monolayer Si-O bonds at the HfO2/Si interface naturally lead to a large potential difference, mainly due to the large dielectric constant of the HfO2. Dipole scattering is demonstrated to not be a major concern in the channel mobility of MOSFETs. PMID:28817060

A Consistency Evaluation and Calibration Method for Piezoelectric Transmitters

PubMed Central

Zhang, Kai; Tan, Baohai; Liu, Xianping

2017-01-01

Array transducer and transducer combination technologies are evolving rapidly. While adapting transmitter combination technologies, the parameter consistencies between each transmitter are extremely important because they can determine a combined effort directly. This study presents a consistency evaluation and calibration method for piezoelectric transmitters by using impedance analyzers. Firstly, electronic parameters of transmitters that can be measured by impedance analyzers are introduced. A variety of transmitter acoustic energies that are caused by these parameter differences are then analyzed and certified and, thereafter, transmitter consistency is evaluated. Lastly, based on the evaluations, consistency can be calibrated by changing the corresponding excitation voltage. Acoustic experiments show that this method accurately evaluates and calibrates transducer consistencies, and is easy to realize. PMID:28452947

Predictors of heart failure in patients with stable coronary artery disease: a PEACE study.

PubMed

Lewis, Eldrin F; Solomon, Scott D; Jablonski, Kathleen A; Rice, Madeline Murguia; Clemenza, Francesco; Hsia, Judith; Maggioni, Aldo P; Zabalgoitia, Miguel; Huynh, Thao; Cuddy, Thomas E; Gersh, Bernard J; Rouleau, Jean; Braunwald, Eugene; Pfeffer, Marc A

2009-05-01

Heart failure (HF) is a disease commonly associated with coronary artery disease. Most risk models for HF development have focused on patients with acute myocardial infarction. The Prevention of Events with Angiotensin-Converting Enzyme Inhibition population enabled the development of a risk model to predict HF in patients with stable coronary artery disease and preserved ejection fraction. In the 8290, Prevention of Events with Angiotensin-Converting Enzyme Inhibition patients without preexisting HF, new-onset HF hospitalizations, and fatal HF were assessed over a median follow-up of 4.8 years. Covariates were evaluated and maintained in the Cox regression multivariable model using backward selection if P<0.05. A risk score was developed and converted to an integer-based scoring system. Among the Prevention of Events with Angiotensin-Converting Enzyme Inhibition population (age, 64+/-8; female, 18%; prior myocardial infarction, 55%), there were 268 cases of fatal and nonfatal HF. Twelve characteristics were associated with increased risk of HF along with several baseline medications, including older age, history of hypertension, and diabetes. Randomization to trandolapril independently reduced the risk of HF. There was no interaction between trandolapril treatment and other risk factors for HF. The risk score (range, 0 to 21) demonstrated excellent discriminatory power (c-statistic 0.80). Risk of HF ranged from 1.75% in patients with a risk score of 0% to 33% in patients with risk score >or=16. Among patients with stable coronary artery disease and preserved ejection fraction, traditional and newer factors were independently associated with increased risk of HF. Trandolopril decreased the risk of HF in these patients with preserved ejection fraction.

Growth, microstructure and electrical properties of sputter-deposited hafnium oxide (HfO2) thin films grown using HfO2 ceramic target

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aguirre, B.; Vemuri, R. S.; Zubia, David

2011-01-01

Hafnium oxide (HfO₂) thin films have been made by radio-frequency (rf) magnetron-sputtering onto Si(100) substrates under varying growth temperature (Ts). HfO₂ ceramic target has been employed for sputtering while varying the Ts from room temperature to 500⁰C during deposition. The effect of Ts on the growth and microstructure of deposited HfO₂ films has been studied using grazing incidence x-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), and high-resolution scanning electron microscopy (HR-SEM) coupled with energy dispersive x-ray spectrometry (EDS). The results indicate that the effect of Ts is significant on the growth, surface and interface structure, morphology and chemical composition ofmore » the HfO₂ films. Structural characterization indicates that the HfO₂ films grown at Ts<200 ⁰C are amorphous while films grown at Ts>200 ⁰C are nanocrystalline. An amorphous-to-crystalline transition occurs at Ts=200 ⁰C. Nanocrystalline HfO₂ films crystallized in a monoclinic structure with a (-111) orientation. XPS measurements indicated the high surface-chemical quality and stoichiometric nature of the grown HfO₂ films. An interface layer (IL) formation occurs due to reaction at the HfO₂-Si interface for HfO₂ films deposited at Ts>200 ⁰C. The thickness of IL increases with increasing Ts. XPS and EDS at the HfO₂-Si cross-section indicate the IL is a (Hf, Si)-O compound. The electrical characterization using capacitance-voltage measurements indicate that the dielectric constant decreases from 25 to 16 with increasing Ts.« less

Probability of Accurate Heart Failure Diagnosis and the Implications for Hospital Readmissions.

PubMed

Carey, Sandra A; Bass, Kyle; Saracino, Giovanna; East, Cara A; Felius, Joost; Grayburn, Paul A; Vallabhan, Ravi C; Hall, Shelley A

2017-04-01

Heart failure (HF) is a complex syndrome with inherent diagnostic challenges. We studied the scope of possibly inaccurately documented HF in a large health care system among patients assigned a primary diagnosis of HF at discharge. Through a retrospective record review and a classification schema developed from published guidelines, we assessed the probability of the documented HF diagnosis being accurate and determined factors associated with HF-related and non-HF-related hospital readmissions. An arbitration committee of 3 experts reviewed a subset of records to corroborate the results. We assigned a low probability of accurate diagnosis to 133 (19%) of the 712 patients. A subset of patients were also reviewed by an expert panel, which concluded that 13% to 35% of patients probably did not have HF (inter-rater agreement, kappa = 0.35). Low-probability HF was predictive of being readmitted more frequently for non-HF causes (p = 0.018), as well as documented arrhythmias (p = 0.023), and age >60 years (p = 0.006). Documented sleep apnea (p = 0.035), percutaneous coronary intervention (p = 0.006), non-white race (p = 0.047), and B-type natriuretic peptide >400 pg/ml (p = 0.007) were determined to be predictive of HF readmissions in this cohort. In conclusion, approximately 1 in 5 patients documented to have HF were found to have a low probability of actually having it. Moreover, the determination of low-probability HF was twice as likely to result in readmission for non-HF causes and, thus, should be considered a determinant for all-cause readmissions in this population. Copyright © 2017 Elsevier Inc. All rights reserved.

Premorbid Body-Mass Index and Mortality after Incident Heart Failure: The Atherosclerosis Risk in Communities Study

PubMed Central

Khalid, Umair; Ather, Sameer; Bavishi, Chirag; Chan, Wenyaw; Loehr, Laura R.; Wruck, Lisa M.; Rosamond, Wayne D.; Chang, Patricia P.; Coresh, Joe; Virani, Salim S.; Nambi, Vijay; Bozkurt, Biykem; Ballantyne, Christie M.; Deswal, Anita

2014-01-01

BACKGROUND Although obesity is an independent risk factor for heart failure (HF), once HF is established, obesity is associated with lower mortality. It is unclear if the weight loss due to advanced HF leads to this paradoxical finding. OBJECTIVES We sought to evaluate the prognostic impact of pre-morbid obesity in patients with HF. METHODS In the Atherosclerosis Risk in Communities (ARIC) study, we used body mass index (BMI) measured ≥6 months before incident HF (pre-morbid BMI) to evaluate the association of overweight (BMI 25 to <30 kg/m2) and obesity (≥30 kg/m2) compared to normal BMI (18.5 to <25 kg/m2) with mortality after incident HF. RESULTS Among 1,487 patients with incident HF, 35% were overweight and 47% were obese by pre-morbid BMI measured 4.3 ± 3.1 years before HF diagnosis. Over 10-year follow-up after incident HF, 43% of patients died. After adjustment for demographics and comorbidities, being premorbidly overweight (hazard ratio [HR]: 0.72; 95% confidence interval [CI[]: 0.58 to 0.90; p = 0.004) or obese (HR: 0.70; 95% CI: 0.56 to 0.87; p = 0.001) had a protective association with survival compared to normal BMI. The protective effect of overweight and obesity was consistent across subgroups based on a history of cancer, smoking, and diabetes. CONCLUSIONS Our results, for the first time, demonstrate that individuals who were overweight or obese before HF development have lower mortality once they have HF compared with normal BMI individuals. Thus, weight loss due to advanced HF may not completely explain the protective effect of higher BMI in HF patients. PMID:25541126

Sardine protein diet increases plasma glucagon-like peptide-1 levels and prevents tissue oxidative stress in rats fed a high-fructose diet.

PubMed

Madani, Zohra; Sener, Abdullah; Malaisse, Willy J; Dalila, Ait Yahia

2015-11-01

The current study investigated whether sardine protein mitigates the adverse effects of fructose on plasma glucagon‑like peptide-1 (GLP-1) and oxidative stress in rats. Rats were fed casein (C) or sardine protein (S) with or without high‑fructose (HF) for 2 months. Plasma glucose, insulin, GLP‑1, lipid and protein oxidation and antioxidant enzymes were assayed. HF rats developed obesity, hyperglycemia, hyperinsulinemia, insulin resistance and oxidative stress despite reduced energy and food intakes. High plasma creatinine and uric acid levels, in addition to albuminuria were observed in the HF groups. The S‑HF diet reduced plasma glucose, insulin, creatinine, uric acid and homeostasis model assessment‑insulin resistance index levels, however increased GLP‑1 levels compared with the C‑HF diet. Hydroperoxides were reduced in the liver, kidney, heart and muscle of S‑HF fed rats compared with C‑HF fed rats. A reduction in liver, kidney and heart carbonyls was observed in S‑HF fed rats compared with C‑HF fed rats. Reduced levels of nitric oxide (NO) were detected in the liver, kidney and heart of the S‑HF fed rats compared with C‑HF fed rats. The S diet compared with the C diet reduced levels of liver hydroperoxides, heart carbonyls and kidney NO. The S‑HF diet compared with the C‑HF diet increased the levels of liver and kidney superoxide dismutase, liver and muscle catalase, liver, heart and muscle glutathione peroxidase and liver ascorbic acid. The S diet prevented and reversed insulin resistance and oxidative stress, and may have benefits in patients with metabolic syndrome.

Distribution and abundance of human-specific Bacteroides and relation to traditional indicators in an urban tropical catchment

PubMed Central

Nshimyimana, J P; Ekklesia, E; Shanahan, P; Chua, L H C; Thompson, J R

2014-01-01

Aims The study goals were to determine the relationship between faecal indicator bacteria (FIB), the HF183 marker and land use, and the phylogenetic diversity of HF183 marker sequences in a tropical urban watershed. Methods and Results Total coliforms, Escherichia coli, and HF183 were quantified in 81 samples categorized as undeveloped, residential and horticultural from the Kranji Reservoir and Catchment in Singapore. Quantitative-PCR for HF183 followed by analysis of variance indicated that horticultural areas had significantly higher geometric means for marker levels (4·3 × 104 HF183-GE 100 ml−1) than nonhorticultural areas (3·07 × 103 HF183-GE 100 ml−1). E. coli and HF183 were moderately correlated in horticultural areas (R = 0·59, P = 0·0077), but not elsewhere in the catchment. Initial upstream surveys of candidate sources revealed elevated HF183 in a wastewater treatment effluent but not in aquaculture ponds. The HF183 marker was cloned, sequenced and determined by phylogenetic analysis to match the original marker description. Conclusion We show that quantification of the HF183 marker is a useful tool for mapping the spatial distribution and potential sources of human sewage contamination in tropical environments such as Singapore. Significance and Impact A major challenge for assessment of water quality in tropical environments is the natural occurrence and nonconservative behaviour of FIB. The HF183 marker has been employed in temperate environments as an alternative indicator for human sewage contamination. Our study supports the use of the HF183 marker as an indicator for human sewage in Singapore and motivates further work to determine HF183 marker levels that correspond to public health risk in tropical environments. PMID:24460587

Elevated pulmonary artery systolic pressure predicts heart failure admissions in African Americans: Jackson Heart Study.

PubMed

Choudhary, Gaurav; Jankowich, Matthew; Wu, Wen-Chih

2014-07-01

Although elevated pulmonary artery systolic pressure (PASP) is associated with heart failure (HF), whether PASP measurement can help predict future HF admissions is not known, especially in African Americans who are at increased risk for HF. We hypothesized that elevated PASP is associated with increased risk of HF admission and improves HF prediction in African American population. We conducted a longitudinal analysis using the Jackson Heart Study cohort (n=3125; 32.2% men) with baseline echocardiography-derived PASP and follow-up for HF admissions. Hazard ratio for HF admission was estimated using Cox proportional hazard model adjusted for variables in the Atherosclerosis Risk in Community (ARIC) HF prediction model. During a median follow-up of 3.46 years, 3.42% of the cohort was admitted for HF. Subjects with HF had a higher PASP (35.6±11.4 versus 27.6±6.9 mm Hg; P<0.001). The hazard of HF admission increased with higher baseline PASP (adjusted hazard ratio per 10 mm Hg increase in PASP: 2.03; 95% confidence interval, 1.67-2.48; adjusted hazard ratio for highest [≥33 mm Hg] versus lowest quartile [<24 mm Hg] of PASP: 2.69; 95% confidence interval, 1.43-5.06) and remained significant irrespective of history of HF or preserved/reduced ejection fraction. Addition of PASP to the ARIC model resulted in a significant improvement in model discrimination (area under the curve=0.82 before versus 0.84 after; P=0.03) and improved net reclassification index (11-15%) using PASP as a continuous or dichotomous (cutoff=33 mm Hg) variable. Elevated PASP predicts HF admissions in African Americans and may aid in early identification of at-risk subjects for aggressive risk factor modification. © 2014 American Heart Association, Inc.

Developmental conditioning of endothelium-derived hyperpolarizing factor-mediated vasorelaxation

PubMed Central

Stead, Rebecca; Musa, Moji G.; Bryant, Claire L.; Lanham, Stuart A.; Johnston, David A.; Reynolds, Richard; Torrens, Christopher; Fraser, Paul A.; Clough, Geraldine F.

2016-01-01

Objectives: The endothelium maintains vascular homeostasis through the release of endothelium-derived relaxing factors (EDRF) and endothelium-derived hyperpolarization (EDH). The balance in EDH : EDRF is disturbed in cardiovascular disease and may also be susceptible to developmental conditioning through exposure to an adverse uterine environment to predispose to later risk of hypertension and vascular disease. Methods: Developmentally conditioned changes in EDH : EDRF signalling pathways were investigated in cremaster arterioles (18–32 μm diameter) and third-order mesenteric arteries of adult male mice offspring of dams fed either a fat-rich (high fat, HF, 45% energy from fat) or control (C, 10% energy from fat) diet. After weaning, offspring either continued on high fat or were placed on control diets to give four dietary groups (C/C, HF/C, C/HF, and HF/HF) and studied at 15 weeks of age. Results: EDH via intermediate (IKCa) and small (SKca) conductance calcium-activated potassium channels contributed less than 10% to arteriolar acetylcholine-induced relaxation in in-situ conditioned HF/C offspring compared with ∼60% in C/C (P < 0.01). The conditioned reduction in EDH signalling in HF/C offspring was reversed in offspring exposed to a high-fat diet both before and after weaning (HF/HF, 55%, P < 0.01 vs. HF/C). EDH signalling was unaffected in arterioles from C/HF offspring. The changes in EDH : EDRF were associated with altered endothelial cell expression and localization of IKCa channels. Conclusion: This is the first evidence that EDH-mediated microvascular relaxation is susceptible to an adverse developmental environment through down-regulation of the IKCa signalling pathway. Conditioned offspring exposed to a ‘second hit’ (HF/HF) exhibit adaptive vascular mechanisms to preserve dilator function. PMID:26682783

Developmental conditioning of endothelium-derived hyperpolarizing factor-mediated vasorelaxation.

PubMed

Stead, Rebecca; Musa, Moji G; Bryant, Claire L; Lanham, Stuart A; Johnston, David A; Reynolds, Richard; Torrens, Christopher; Fraser, Paul A; Clough, Geraldine F

2016-03-01

The endothelium maintains vascular homeostasis through the release of endothelium-derived relaxing factors (EDRF) and endothelium-derived hyperpolarization (EDH). The balance in EDH : EDRF is disturbed in cardiovascular disease and may also be susceptible to developmental conditioning through exposure to an adverse uterine environment to predispose to later risk of hypertension and vascular disease. Developmentally conditioned changes in EDH : EDRF signalling pathways were investigated in cremaster arterioles (18-32  μm diameter) and third-order mesenteric arteries of adult male mice offspring of dams fed either a fat-rich (high fat, HF, 45% energy from fat) or control (C, 10% energy from fat) diet. After weaning, offspring either continued on high fat or were placed on control diets to give four dietary groups (C/C, HF/C, C/HF, and HF/HF) and studied at 15 weeks of age. EDH via intermediate (IKCa) and small (SKca) conductance calcium-activated potassium channels contributed less than 10% to arteriolar acetylcholine-induced relaxation in in-situ conditioned HF/C offspring compared with ∼60% in C/C (P < 0.01). The conditioned reduction in EDH signalling in HF/C offspring was reversed in offspring exposed to a high-fat diet both before and after weaning (HF/HF, 55%, P < 0.01 vs. HF/C). EDH signalling was unaffected in arterioles from C/HF offspring. The changes in EDH : EDRF were associated with altered endothelial cell expression and localization of IKCa channels. This is the first evidence that EDH-mediated microvascular relaxation is susceptible to an adverse developmental environment through down-regulation of the IKCa signalling pathway. Conditioned offspring exposed to a 'second hit' (HF/HF) exhibit adaptive vascular mechanisms to preserve dilator function.

Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography.

PubMed

Nagai, Yuichiro; Yokoyama, Tetsuya

2014-05-20

A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

Effect of Light-Cured Resin Cement Application on Translucency of Ceramic Veneers and Light Transmission of LED Polymerization Units.

PubMed

Zhang, Lei; Luo, Xiao Ping; Tan, Ren Xiang

2018-05-31

To evaluate the effect of light-cured resin cement application based on etching and silanization on the translucent property of ceramic veneers in different thicknesses, testing the hypothesis that the surface treatment and subsequent resin cement application could influence the translucency of ceramic veneers. The relationship between translucency of ceramic veneers and light transmission irradiated by LED polymerization units was also determined. 40 specimens (10 mm diameter) were fabricated from IPS e.max Press HT A2 ceramic ingots, and polished to 0.3 ± 0.01 mm, 0.5 ± 0.01 mm, 0.7 ± 0.01 mm, 1.0 ± 0.01 mm, and 1.5 ± 0.01 mm thick (n = 8/group). One surface of each disc was etched with HF acid, silanized with Monobond-S, and applied with a light-cured resin cement (Variolink N Transparent Base). Before and after the above procedure, the total luminous transmittance (τ) of all specimens was assessed by a spectrophotometer in a wavelength range of 380-780 nm. A handheld radiometer was used to measure the light intensity irradiated by three LED polymerization units. Light transmission (LT) through ceramic specimens after resin cement application was calculated. Data were statistically analyzed using two-way ANOVA (p = 0.05) and Tukey's test. The correlation between translucency (τ) of ceramic veneers after resin cement application and light transmission (LT) of curing units was statistically evaluated using Spearman correlation test (p = 0.05). With the increase of ceramic thickness, the transmittance decreased significantly (p < 0.05). For the 0.3-mm, 0.5-mm, and 0.7-mm-thick groups, the transmittance of ceramic specimens was statistically significantly lower after resin cement application (p < 0.05). The r value of Bluephase C8 was 0.988, 0.977 for Bluphase, and 0.883 for Bluephase 20i, indicating that the light transmission (LT%) was positively correlated to the translucency of ceramic veneers, regardless of the type of curing units. After the light-cured resin cement application based on etching and silanization, the ceramic veneers (less than 0.7-mm thick) were less translucent, and the translucency decreased when the thickness increased. Because of the lower translucency of ceramic veneers, the light intensity of LED units transmitted to resin layer would decrease when curing. © 2018 by the American College of Prosthodontists.

Metabolism of halofantrine to its equipotent metabolite, desbutylhalofantrine, is decreased when orally administered with ketoconazole.

PubMed

Khoo, S M; Porter, J H; Edwards, G A; Charman, W N

1998-12-01

Halofantrine (Hf) is a highly lipophilic antimalarial with poor and erratic absorption. Published data indicates that the oral bioavailability of Hf was increased 3-fold in humans and 12-fold in dogs when administered postprandially; however, the proportional formation of the active desbutyl metabolite (desbutylhalofantrine, Hfm) decreased 2.4-fold in humans and 6.8-fold in dogs (Milton et al., Br. J. Clin. Pharmacol. 1989, 28, 71-77; Humberstone et al., J. Pharm. Sci. 1996, 85, 525-529). The current study was undertaken to confirm the putative involvement of CYP3A4 in the N-dealkylation of Hf to Hfm by administering Hf with and without ketoconazole (KC), a specific CYP3A4 inhibitor, and measuring the resulting plasma concentration profiles of Hf and Hfm. The plasma Hfm/Hf AUC(0-72 h) ratio after fasted oral administration of Hf without KC was 0.56, whereas the ratio after fasted oral administration with KC was less than 0.05. It is likely that both hepatic and prehepatic (enterocyte-based) CYP3A4 contributed to metabolism of Hf to Hfm after oral administration. Interestingly, the low plasma Hfm/Hf AUC ratios observed after fasted administration of Hf with KC were similar to the low values previously observed when Hf was administered postprandially (despite increased Hf absorption). The mechanism(s) by which postprandial administration of Hf led to a decrease in its metabolism are unknown, but based on the current data, could include inhibition of CYP3A4-mediated metabolism by components of the ingested meal. Other possibilities include a lipid-induced postprandial recruitment of intestinal lymphatic transport or avoidance of metabolism during transport through the enterocyte into the portal blood. Further studies are required to determine the relative contributions by which these different processes may decrease the presystemic metabolism of Hf.

Loss of ovarian function in the VCD mouse-model of menopause leads to insulin resistance and a rapid progression into the metabolic syndrome.

PubMed

Romero-Aleshire, Melissa J; Diamond-Stanic, Maggie K; Hasty, Alyssa H; Hoyer, Patricia B; Brooks, Heddwen L

2009-09-01

Factors comprising the metabolic syndrome occur with increased incidence in postmenopausal women. To investigate the effects of ovarian failure on the progression of the metabolic syndrome, female B(6)C(3)F(1) mice were treated with 4-vinylcyclohexene diepoxide (VCD) and fed a high-fat (HF) diet for 16 wk. VCD destroys preantral follicles, causing early ovarian failure and is a well-characterized model for the gradual onset of menopause. After 12 wk on a HF diet, VCD-treated mice had developed an impaired glucose tolerance, whereas cycling controls were unaffected [12 wk AUC HF mice 13,455 +/- 643 vs. HF/VCD 17,378 +/- 1140 mg/dl/min, P < 0.05]. After 16 wk on a HF diet, VCD-treated mice had significantly higher fasting insulin levels (HF 5.4 +/- 1.3 vs. HF/VCD 10.1 +/- 1.4 ng/ml, P < 0.05) and were significantly more insulin resistant (HOMA-IR) than cycling controls on a HF diet (HF 56.2 +/- 16.7 vs. HF/VCD 113.1 +/- 19.6 mg/dl x microU/ml, P < 0.05). All mice on a HF diet gained more weight than mice on a standard diet, and weight gain in HF/VCD mice was significantly increased compared with HF cycling controls. Interestingly, even without a HF diet, progression into VCD-induced menopause caused a significant increase in cholesterol and free fatty acids. Furthermore, in mice fed a standard diet (6% fat), insulin resistance developed 4 mo after VCD-induced ovarian failure. Insulin resistance following ovarian failure (menopause) was prevented by estrogen replacement. Studies here demonstrate that ovarian failure (menopause) accelerates progression into the metabolic syndrome and that estrogen replacement prevents the onset of insulin resistance in VCD-treated mice. Thus, the VCD model of menopause provides a physiologically relevant means of studying how sex hormones influence the progression of the metabolic syndrome.

N-Terminal Pro-Brain Natriuretic Peptide and Heart Failure Risk Among Individuals With and Without Obesity: The Atherosclerosis Risk in Communities (ARIC) Study.

PubMed

Ndumele, Chiadi E; Matsushita, Kunihiro; Sang, Yingying; Lazo, Mariana; Agarwal, Sunil K; Nambi, Vijay; Deswal, Anita; Blumenthal, Roger S; Ballantyne, Christie M; Coresh, Josef; Selvin, Elizabeth

2016-02-16

Obesity is a risk factor for heart failure (HF) but is associated with lower N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. It is unclear whether the prognostic value and implications of NT-proBNP levels for HF risk differ across body mass index (BMI) categories. We followed up 12 230 ARIC participants free of prior HF at baseline (visit 2, 1990-1992) with BMI ≥18.5 kg/m(2). We quantified and compared the relative and absolute risk associations of NT-proBNP with incident HF across BMI categories. There were 1861 HF events during a median 20.6 years of follow-up. Despite increased HF risk in obesity, a weak inverse association was seen between baseline BMI and NT-proBNP levels (r=-0.10). Nevertheless, higher baseline NT-proBNP was associated with increased HF risk in all BMI categories. NT-proBNP improved HF risk prediction overall, even among those with severe obesity (BMI ≥35 kg/m(2); improvement in C statistic, 0.032; 95% confidence interval, 0.011-0.053). However, given the higher HF rates among those with obesity, at each NT-proBNP level, higher BMI was associated with greater absolute HF risk. Indeed, among those with NT-proBNP of 100 to <200 pg/mL, the average 10-year HF risk was <5% among normal-weight individuals but >10% among the severely obese. Despite its inverse relationship with BMI, NT-proBNP provides significant prognostic information on the risk of developing HF even among individuals with obesity. Given the higher baseline HF risk among persons with obesity, even slight elevations in NT-proBNP may have implications for increased absolute HF risk in this population. © 2016 American Heart Association, Inc.

The very low-frequency band of heart rate variability represents the slow recovery component after a mental stress task.

PubMed

Usui, Harunobu; Nishida, Yusuke

2017-01-01

The very low-frequency (VLF) band of heart rate variability (HRV) has different characteristics compared with other HRV components. Here we investigated differences in HRV changes after a mental stress task. After the task, the high-frequency (HF) band and ratio of high- to low-frequency bands (LF/HF) immediately returned to baseline. We evaluated the characteristics of VLF band changes after a mental stress task. We hypothesized that the VLF band decreases during the Stroop color word task and there would be a delayed recovery for 2 h after the task (i.e., the VLF change would exhibit a "slow recovery"). Nineteen healthy, young subjects were instructed to rest for 10 min, followed by a Stroop color word task for 20 min. After the task, the subjects were instructed to rest for 120 min. For all subjects, R-R interval data were collected; analysis was performed for VLF, HF, and LF/HF ratio. HRV during the rest time and each 15-min interval of the recovery time were compared. An analysis of the covariance was performed to adjust for the HF band and LF/HF ratio as confounding variables of the VLF component. HF and VLF bands significantly decreased and the LF/HF ratio significantly increased during the task compared with those during rest time. During recovery, the VLF band was significantly decreased compared with the rest time. After the task, the HF band and LF/HF ratio immediately returned to baseline and were not significantly different from the resting values. After adjusting for HF and LF/HF ratio, the VLF band had significantly decreased compared with that during rest. The VLF band is the "slow recovery" component and the HF band and LF/HF ratio are the "quick recovery" components of HRV. This VLF characteristic may clarify the unexplained association of the VLF band in cardiovascular disease prevention.

Choline supplementation protects against liver damage by normalizing cholesterol metabolism in Pemt/Ldlr knockout mice fed a high-fat diet.

PubMed

Al Rajabi, Ala; Castro, Gabriela S F; da Silva, Robin P; Nelson, Randy C; Thiesen, Aducio; Vannucchi, Helio; Vine, Donna F; Proctor, Spencer D; Field, Catherine J; Curtis, Jonathan M; Jacobs, René L

2014-03-01

Dietary choline is required for proper structure and dynamics of cell membranes, lipoprotein synthesis, and methyl-group metabolism. In mammals, choline is synthesized via phosphatidylethanolamine N-methyltransferase (Pemt), which converts phosphatidylethanolamine to phosphatidylcholine. Pemt(-/-) mice have impaired VLDL secretion and developed fatty liver when fed a high-fat (HF) diet. Because of the reduction in plasma lipids, Pemt(-/-)/low-density lipoprotein receptor knockout (Ldlr(-/-)) mice are protected from atherosclerosis. The goal of this study was to investigate the importance of dietary choline in the metabolic phenotype of Pemt(-/-)/Ldlr(-/-) male mice. At 10-12 wk of age, Pemt(+/+)/Ldlr(-/-) (HF(+/+)) and half of the Pemt(-/-)/Ldlr(-/-) (HF(-/-)) mice were fed an HF diet with normal (1.3 g/kg) choline. The remaining Pemt(-/-)/Ldlr(-/-) mice were fed an HF diet supplemented (5 g/kg) with choline (HFCS(-/-) mice). The HF diet contained 60% of calories from fat and 1% cholesterol, and the mice were fed for 16 d. HF(-/-) mice lost weight and developed hepatomegaly, steatohepatitis, and liver damage. Hepatic concentrations of free cholesterol, cholesterol-esters, and triglyceride (TG) were elevated by 30%, 1.1-fold and 3.1-fold, respectively, in HF(-/-) compared with HF(+/+) mice. Choline supplementation normalized hepatic cholesterol, but not TG, and dramatically improved liver function. The expression of genes involved in cholesterol transport and esterification increased by 50% to 5.6-fold in HF(-/-) mice when compared with HF(+/+) mice. Markers of macrophages, oxidative stress, and fibrosis were elevated in the HF(-/-) mice. Choline supplementation normalized the expression of these genes. In conclusion, HF(-/-) mice develop liver failure associated with altered cholesterol metabolism when fed an HF/normal choline diet. Choline supplementation normalized cholesterol metabolism, which was sufficient to prevent nonalcoholic steatohepatitis development and improve liver function. Our data suggest that choline can promote liver health by maintaining cholesterol homeostasis.

Prevalence and outcome of Middle-eastern Arab and South Asian patients hospitalized with heart failure: insight from a 20-year registry in a Middle-eastern country (1991-2010).

PubMed

Al Suwaidi, Jassim; Asaad, Nidal; Al-Qahtani, Awad; Al-Mulla, Abdul Wahid; Singh, Rajvir; Albinali, Hajar A

2012-06-01

The clinical characteristics and outcome of patients hospitalized with heart failure vary according to ethnicities. Limited epidemiologic data are available about the clinical characteristics and outcome of heart failure (HF) patients among non-Caucasian populations. Between 1 January 1991 and 31 December 2010; 41 453 consecutive patients were hospitalized at Hamad General Hospital, Doha, Qatar for cardiac reasons. Patients were into two groups; hospitalized with HF (n = 7069) and hospitalized for non-HF (no-HF). Among HF patients Sub-analysis was made according to ethnicity; Middle-eastern Arabs (MEA) (n = 5227) versus South Asian (SA) (n = 1289) patients. HF patients were older and more likely to be female when compared to non-HF patients. HF patients were also more likely to have diabetes mellitus (DM), hypertension (HTN), atrial fibrillation (AF) and renal impairment when compared to non-HF patients. SA HF patients younger and less likely to have DM, HTN and AF when compared to MEA patients. Over the 20-years period there was decrease in in-hospital mortality and stroke rates regardless of ethnicity (death; 8.3% to 4.8%, stroke; 0.8% to 0.1%; all P = 0.001). HF patients in the Middle East present at relatively younger age regardless of ethnicity. In-hospital mortality and stroke rates decreased significantly over the 20-years.

New Oxide Materials for an Ultra High Temperature Environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perepezko, John H.

In this project, a new oxide material, Hf 6Ta 2O 17 has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf 6Ta 2O 17 with amore » complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf 6Ta 2O 17 superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO 2 and Ta 2O 5 and verified the low thermal conductivity of Hf 6Ta 2O 17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf 6Ta 2O 17, which shows an initial parabolic oxidation kinetics.« less

Effects of Gibbs free energy of interfacial metal oxide on resistive switching characteristics of solution-processed HfOx films

NASA Astrophysics Data System (ADS)

Hsu, Chih-Chieh; Sun, Jhen-Kai; Tsao, Che-Chang; Chuang, Po-Yang

2017-08-01

Effects of bottom electrodes (BEs) of Al, Mo, and Pt on resistive switching characteristics of sol-gel HfOx films were investigated in this work. To avoid influences of plasma or thermal energy on HfOx RS characteristic, the top electrodes were formed by pressing indium balls onto the HfOx surface rather than by using a sputter or an evaporator. When using Mo as the BE, the as-deposited HfOx film can give a forming-free resistive switching behavior with low set/reset voltages of 0.28 V / - 0.54 V. In contrast, non-switching characteristics of the HfOx films were observed when using Al and Pt as the BEs. The HfOx conduction current was found to be highly dependent on the BE. However, when an annealing process at 350 °C in an oxygen ambient was performed to the HfOx films on different BEs, the resistive switching behavior of the HfOx/Mo was absent while it can be found in the HfOx/Al sample. Differences in I-V characteristics of the HfOx films on different BEs were explained by considering Gibbs free energies of interfacial oxide layers. X-ray photoelectron spectroscopy (XPS) depth profile was used to examine the interfacial oxide layer. The resistive switching mechanism was also studied.

Electron holography on HfO2/HfO2-x bilayer structures with multilevel resistive switching properties

NASA Astrophysics Data System (ADS)

Niu, G.; Schubert, M. A.; Sharath, S. U.; Zaumseil, P.; Vogel, S.; Wenger, C.; Hildebrandt, E.; Bhupathi, S.; Perez, E.; Alff, L.; Lehmann, M.; Schroeder, T.; Niermann, T.

2017-05-01

Unveiling the physical nature of the oxygen-deficient conductive filaments (CFs) that are responsible for the resistive switching of the HfO2-based resistive random access memory (RRAM) devices represents a challenging task due to the oxygen vacancy related defect nature and nanometer size of the CFs. As a first important step to this goal, we demonstrate in this work direct visualization and a study of physico-chemical properties of oxygen-deficient amorphous HfO2-x by carrying out transmission electron microscopy electron holography as well as energy dispersive x-ray spectroscopy on HfO2/HfO2-x bilayer heterostructures, which are realized by reactive molecular beam epitaxy. Furthermore, compared to single layer devices, Pt/HfO2/HfO2-x /TiN bilayer devices show enhanced resistive switching characteristics with multilevel behavior, indicating their potential as electronic synapses in future neuromorphic computing applications.

New diagnostic modalities in the diagnosis of heart failure.

PubMed Central

Mitchell, Judith E.; Palta, Sanjeev

2004-01-01

Heart failure (HF) is the one cardiovascular disease that is increasing in prevalence in the United States. As the population continues to age, the incidence will certainly be amplified. However, some studies have shown that HF is correctly diagnosed initially in only 50% of affected patients. Despite the use of history, physical examination, echocardiogram, and chest x-ray, the percentage of correct initial diagnosis of HF is low. Recognizing the symptoms of HF decompensations is often problematic because other diagnoses can mimic them. There are two new diagnostic modalities that offer promise in improving HF diagnostic accuracy and identifying early HF decompensations. These diagnostic modalities include tests utilizing impedance cardiography and the B-type natriuretic peptide assay. They have the potential of increasing the accuracy of HF diagnosis and guide pharmacological treatment in the inpatient and outpatient settings. They may also assist in the recognition (or prediction) of acute HF decompensations. Images Figure 2 PMID:15586645

The effect of statin therapy on heart failure events: a collaborative meta-analysis of unpublished data from major randomized trials.

PubMed

Preiss, David; Campbell, Ross T; Murray, Heather M; Ford, Ian; Packard, Chris J; Sattar, Naveed; Rahimi, Kazem; Colhoun, Helen M; Waters, David D; LaRosa, John C; Amarenco, Pierre; Pedersen, Terje R; Tikkanen, Matti J; Koren, Michael J; Poulter, Neil R; Sever, Peter S; Ridker, Paul M; MacFadyen, Jean G; Solomon, Scott D; Davis, Barry R; Simpson, Lara M; Nakamura, Haruo; Mizuno, Kyoichi; Marfisi, Rosa M; Marchioli, Roberto; Tognoni, Gianni; Athyros, Vasilios G; Ray, Kausik K; Gotto, Antonio M; Clearfield, Michael B; Downs, John R; McMurray, John J

2015-06-21

The effect of statins on risk of heart failure (HF) hospitalization and HF death remains uncertain. We aimed to establish whether statins reduce major HF events. We searched Medline, EMBASE, and the Cochrane Central Register of Controlled Trials for randomized controlled endpoint statin trials from 1994 to 2014. Collaborating trialists provided unpublished data from adverse event reports. We included primary- and secondary-prevention statin trials with >1000 participants followed for >1 year. Outcomes consisted of first non-fatal HF hospitalization, HF death and a composite of first non-fatal HF hospitalization or HF death. HF events occurring <30 days after within-trial myocardial infarction (MI) were excluded. We calculated risk ratios (RR) with fixed-effects meta-analyses. In up to 17 trials with 132 538 participants conducted over 4.3 [weighted standard deviation (SD) 1.4] years, statin therapy reduced LDL-cholesterol by 0.97 mmol/L (weighted SD 0.38 mmol/L). Statins reduced the numbers of patients experiencing non-fatal HF hospitalization (1344/66 238 vs. 1498/66 330; RR 0.90, 95% confidence interval, CI 0.84-0.97) and the composite HF outcome (1234/57 734 vs. 1344/57 836; RR 0.92, 95% CI 0.85-0.99) but not HF death (213/57 734 vs. 220/57 836; RR 0.97, 95% CI 0.80-1.17). The effect of statins on first non-fatal HF hospitalization was similar whether this was preceded by MI (RR 0.87, 95% CI 0.68-1.11) or not (RR 0.91, 95% CI 0.84-0.98). In primary- and secondary-prevention trials, statins modestly reduced the risks of non-fatal HF hospitalization and a composite of non-fatal HF hospitalization and HF death with no demonstrable difference in risk reduction between those who suffered an MI or not. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Atmospheric chemistry of hydrogen fluoride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Meng -Dawn

In this study, the atmospheric chemistry, emissions, and surface boundary layer transport of hydrogen fluoride (HF) is summarized. Although HF is known to be chemically reactive and highly soluble, both factors affect transport and removal in the atmosphere, we suggest that the chemistry can be ignored when the HF concentration is at a sufficiently low level (e.g., 10 ppmv). At a low concentration, the capability for HF to react in the atmosphere is diminished and therefore the species can be mathematically treated as inert during the transport. At a sufficiently high concentration of HF (e.g., kg/s release rate and thousandsmore » of ppm), however, HF can go through a series of rigorous chemical reactions including polymerization, depolymerization, and reaction with water to form molecular complex. As such, the HF species cannot be considered as inert because the reactions could intimately influence the plume s thermodynamic properties affecting the changes in plume temperature and density. The atmospheric residence time of HF was found to be less than four (4) days, and deposition (i.e., atmosphere to surface transport) is the dominant mechanism that controls the removal of HF and its oligomers from the atmosphere. The literature data on HF dry deposition velocity was relatively high compared to many commonly found atmospheric species such as ozone, sulfur dioxide, nitrogen oxides, etc. The global average of wet deposition velocity of HF was found to be zero based on one literature source. Uptake of HF by rain drops is limited by the acidity of the rain drops, and atmospheric particulate matter contributes negligibly to HF uptake. Finally, given that the reactivity of HF at a high release rate and elevated mole concentration cannot be ignored, it is important to incorporate the reaction chemistry in the near-field dispersion close to the proximity of the release source, and to incorporate the deposition mechanism in the far-field dispersion away from the release source. In other words, a hybrid computational scheme may be needed to address transport and atmospheric chemistry of HF in a range of applications. The model uncertainty will be limited by the precision of boundary layer parameterization and ability to accurately model the atmospheric turbulence.« less

Atmospheric chemistry of hydrogen fluoride

DOE PAGES

Cheng, Meng -Dawn

2017-04-11

In this study, the atmospheric chemistry, emissions, and surface boundary layer transport of hydrogen fluoride (HF) is summarized. Although HF is known to be chemically reactive and highly soluble, both factors affect transport and removal in the atmosphere, we suggest that the chemistry can be ignored when the HF concentration is at a sufficiently low level (e.g., 10 ppmv). At a low concentration, the capability for HF to react in the atmosphere is diminished and therefore the species can be mathematically treated as inert during the transport. At a sufficiently high concentration of HF (e.g., kg/s release rate and thousandsmore » of ppm), however, HF can go through a series of rigorous chemical reactions including polymerization, depolymerization, and reaction with water to form molecular complex. As such, the HF species cannot be considered as inert because the reactions could intimately influence the plume s thermodynamic properties affecting the changes in plume temperature and density. The atmospheric residence time of HF was found to be less than four (4) days, and deposition (i.e., atmosphere to surface transport) is the dominant mechanism that controls the removal of HF and its oligomers from the atmosphere. The literature data on HF dry deposition velocity was relatively high compared to many commonly found atmospheric species such as ozone, sulfur dioxide, nitrogen oxides, etc. The global average of wet deposition velocity of HF was found to be zero based on one literature source. Uptake of HF by rain drops is limited by the acidity of the rain drops, and atmospheric particulate matter contributes negligibly to HF uptake. Finally, given that the reactivity of HF at a high release rate and elevated mole concentration cannot be ignored, it is important to incorporate the reaction chemistry in the near-field dispersion close to the proximity of the release source, and to incorporate the deposition mechanism in the far-field dispersion away from the release source. In other words, a hybrid computational scheme may be needed to address transport and atmospheric chemistry of HF in a range of applications. The model uncertainty will be limited by the precision of boundary layer parameterization and ability to accurately model the atmospheric turbulence.« less

High Frequency Active Auroral Research Program (HAARP) Imager

DTIC Science & Technology

1993-09-30

T-3 HCTL!; *WR-EN HCTL@ F- 3 HC7L! ; * HACK H(TL-@ F-4 HCTL!; ]NIiT-HOST 00 HB! F8 HCrL!; DSP-RESET INIT-HOST HCTL@ DUP F-6 HCTh! T-6 HCTU! DSP-IRQB...CONSTANTPS2 PI_HI P2-11 OR 3_-1O OR TG..LO OR CONSTANT PS3 P1I.,O P2_.i OR P3..LO OR TG_.LO OR CONSTANT PS4 PlLO P21-1I OR P3_H1 OR TGIIl OR CONSTANTPS5 P1_LO...CONSTANT PSTATEI PS2 SER-IDLE OR CONSTANT PSTATE2 PS3 SERIDLE OR CONSTANT PSTATE3 PS4 SERIDLE OR CONSTANT PSTATE4 PS5 SERIDLE OR CONSTANT PSTATES PS6

Full-Scale Numerical Modeling of Turbulent Processes in the Earth's Ionosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eliasson, B.; Stenflo, L.; Department of Physics, Linkoeping University, SE-581 83 Linkoeping

2008-10-15

We present a full-scale simulation study of ionospheric turbulence by means of a generalized Zakharov model based on the separation of variables into high-frequency and slow time scales. The model includes realistic length scales of the ionospheric profile and of the electromagnetic and electrostatic fields, and uses ionospheric plasma parameters relevant for high-latitude radio facilities such as Eiscat and HAARP. A nested grid numerical method has been developed to resolve the different length-scales, while avoiding severe restrictions on the time step. The simulation demonstrates the parametric decay of the ordinary mode into Langmuir and ion-acoustic waves, followed by a Langmuirmore » wave collapse and short-scale caviton formation, as observed in ionospheric heating experiments.« less

High Frequency Active Auroral Research Program (HAARP) imager. Final report, 29 August 1991-29 August 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lance, C.; Eather, R.

1993-09-30

A low-light-level monochromatic imaging system was designed and fabricated which was optimized to detect and record optical emissions associated with high-power rf heating of the ionosphere. The instrument is capable of detecting very low intensities, of the order of 1 Rayleigh, from typical ionospheric atomic and molecular emissions. This is achieved through co-adding of ON images during heater pulses and subtraction of OFF (background) images between pulses. Images can be displayed and analyzed in real time and stored in optical disc for later analysis. Full image processing software is provided which was customized for this application and uses menu ormore » mouse user interaction.« less

Educational Needs for Improving Self-care in Heart Failure Patients with Diabetes

PubMed Central

Cha, Eun Seok; Clark, Patricia C.; Reilly, Carolyn Miller; Higgins, Melinda; Lobb, Maureen; Smith, Andrew L.; Dunbar, Sandra B.

2013-01-01

Purpose To explore the need for self-monitoring and self-care education in heart failure patients with diabetes (HF-DM patients) by describing cognitive and affective factors to provide guidance in developing effective self- management education. Method A cross-sectional correlation design was employed using baseline patient data from a study testing a 12 week patient and family dyad intervention to improve dietary and medication-taking self-management behaviors in HF patients. Data from 116 participants recruited from metropolitan Atlanta area were used. Demographic and co-morbidities, physical function, psychological distress, relationship with health care provider, self-efficacy (medication taking and low sodium diet), and behavioral outcomes (medications, dietary habits) were assessed. Descriptive statistics and a series of chi-square tests, t-tests or Mann Whitney tests were performed to compare HF patients with and without DM. Results HF-DM patients were older, heavier, had more co- morbidities, and took more daily medications than HF patients. High self-efficacy on medication and low sodium diet was reported in both groups with no significant difference. Although HF-DM patients took more daily medications than HF, both groups exhibited high HF medication taking behaviors. The HF-DM patients consumed significantly lower total sugar than HF patients, but clinically higher levels of sodium. Conclusions Diabetes educators need to be aware of potential conflicts of treatment regimens to manage two chronic diseases. Special and integrated diabetes self-management education programs which incorporate principles of HF self-management should be developed to improve self-management behavior in HF-DM patients. PMID:22722611

Real world heart failure epidemiology and outcome: A population-based analysis of 88,195 patients

PubMed Central

Vela, Emili; Clèries, Montse; Bustins, Montse; Cainzos-Achirica, Miguel; Enjuanes, Cristina; Moliner, Pedro; Ruiz, Sonia; Verdú-Rotellar, José María; Comín-Colet, Josep

2017-01-01

Background Heart failure (HF) is frequent and its prevalence is increasing. We aimed to evaluate the epidemiologic features of HF patients, the 1-year follow-up outcomes and the independent predictors of those outcomes at a population level. Methods and results Population-based longitudinal study including all prevalent HF cases in Catalonia (Spain) on December 31st, 2012. Patients were divided in 3 groups: patients without a previous HF hospitalization, patients with a remote (>1 year) HF hospitalization and patients with a recent (<1 year) HF admission. We analyzed 1year all-cause and HF hospitalizations, and all-cause mortality. Logistic regression was used to identify the independent predictors of each of those outcomes. A total of 88,195 patients were included. Mean age was 77 years, 55% were women. Comorbidities were frequent. Fourteen percent of patients had never been hospitalized, 71% had a remote HF hospitalization and 15% a recent hospitalization. At 1-year follow-up, all-cause and HF hospitalization were 53% and 8.8%, respectively. One-year all-cause mortality rate was 14%, and was higher in patients with a recent HF hospitalization (24%). The presence of diabetes mellitus, atrial fibrillation or chronic kidney disease was independently associated with all-cause and HF hospitalization and all-cause mortality. Hospital admissions and emergency department visits the previous year were also found to be independently associated with the three study outcomes. Conclusions Outcomes are different depending on the HF population studied. Some comorbidity, an all-cause hospitalization or emergency department visit the previous year were associated with a worse outcome. PMID:28235067

Real world heart failure epidemiology and outcome: A population-based analysis of 88,195 patients.

PubMed

Farré, Núria; Vela, Emili; Clèries, Montse; Bustins, Montse; Cainzos-Achirica, Miguel; Enjuanes, Cristina; Moliner, Pedro; Ruiz, Sonia; Verdú-Rotellar, José María; Comín-Colet, Josep

2017-01-01

Heart failure (HF) is frequent and its prevalence is increasing. We aimed to evaluate the epidemiologic features of HF patients, the 1-year follow-up outcomes and the independent predictors of those outcomes at a population level. Population-based longitudinal study including all prevalent HF cases in Catalonia (Spain) on December 31st, 2012. Patients were divided in 3 groups: patients without a previous HF hospitalization, patients with a remote (>1 year) HF hospitalization and patients with a recent (<1 year) HF admission. We analyzed 1year all-cause and HF hospitalizations, and all-cause mortality. Logistic regression was used to identify the independent predictors of each of those outcomes. A total of 88,195 patients were included. Mean age was 77 years, 55% were women. Comorbidities were frequent. Fourteen percent of patients had never been hospitalized, 71% had a remote HF hospitalization and 15% a recent hospitalization. At 1-year follow-up, all-cause and HF hospitalization were 53% and 8.8%, respectively. One-year all-cause mortality rate was 14%, and was higher in patients with a recent HF hospitalization (24%). The presence of diabetes mellitus, atrial fibrillation or chronic kidney disease was independently associated with all-cause and HF hospitalization and all-cause mortality. Hospital admissions and emergency department visits the previous year were also found to be independently associated with the three study outcomes. Outcomes are different depending on the HF population studied. Some comorbidity, an all-cause hospitalization or emergency department visit the previous year were associated with a worse outcome.

Effects of HfB2 and HfN Additions on the Microstructures and Mechanical Properties of TiB2-Based Ceramic Tool Materials

PubMed Central

An, Jing; Song, Jinpeng; Liang, Guoxing; Gao, Jiaojiao; Xie, Juncai; Cao, Lei; Wang, Shiying; Lv, Ming

2017-01-01

The effects of HfB2 and HfN additions on the microstructures and mechanical properties of TiB2-based ceramic tool materials were investigated. The results showed that the HfB2 additive not only can inhibit the TiB2 grain growth but can also change the morphology of some TiB2 grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB2-HfB2 ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB2 and Ni. The decrease of the flexural strength and Vickers hardness of the TiB2-HfN ceramics was due to the increase of defects such as TiB2 coarse grains and HfN agglomeration; the enhancement of fracture toughness was mainly attributed to the decrease of the pore number and the increase of the rim phase and TiB2 coarse grains. The toughening mechanisms of TiB2-HfB2 ceramics mainly included crack bridging and transgranular fracture, while the toughening mechanisms of TiB2-HfN ceramics mainly included crack deflection, crack bridging, transgranular fracture, and the core-rim structure. PMID:28772821

Effect of Intraperitoneal Radiotelemetry Instrumentation on Voluntary Wheel Running and Surgical Recovery in Mice

PubMed Central

Helwig, Bryan G; Ward, Jermaine A; Blaha, Michael D; Leon, Lisa R

2012-01-01

Radiotelemetry transmitters support tracking of physiologic variables in conscious animals, but the size of the transmitter may alter animal health and behavior. We hypothesized that the size of the device adversely affects body weight, food intake, water intake, circadian core temperature, activity, voluntary running patterns, and the health of internal organs and that these negative effects can be minimized with smaller transmitter devices. Male C57BL/6J mice (weight, 20 to 24 g) were implanted with small (1.1 g, 0.52 mL) or large (3.5 g, 1.75 mL) radiotransmitters. Recovery of presurgical body weight, food intake, and water intake occurred within 3 d in mice implanted with small transmitter and 9 d in those with large transmitters. Mice with small transmitters displayed robust circadian core body temperature and activity patterns within 1 d after surgery, whereas activity was depressed in mice with large transmitters throughout experimentation. The most robust effects of the large transmitter included significantly reduced voluntary running, which never recovered to baseline, and inflammation of the diaphragm, large intestine, and duodenum. These results demonstrate that the large transmitter delayed surgical recovery, disrupted normal growth, reduced voluntary running, and induced inflammatory reactions of the internal organs of mice. The choice of radiotelemetry transmitter can significantly affect the health and wellbeing of experimental mice as well as data quality, such that the smallest transmitter device available and appropriate to the situation should be chosen for experimentation. PMID:23312089

46 CFR 113.35-7 - Electric engine order telegraph systems; operations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... transmitter handle automatically connects that transmitter electrically to the engineroom indicator and simultaneously disconnects electrically all other transmitters. The reply pointers of all transmitters must... manually operated transfer switch which will disconnect the system in the unattended navigating bridge must...

47 CFR 90.203 - Certification required.

Code of Federal Regulations, 2013 CFR

2013-10-01

... controls. (f) Except as provided in paragraph (g) of this section, transmitters designed to operate above... external controls, to program the transmitter's operating frequencies, shall not be manufactured in, or... such transmitters: (1) Is such that transmitters with external controls normally available to the...

What Hf isotopes in zircon tell us about crust-mantle evolution

NASA Astrophysics Data System (ADS)

Iizuka, Tsuyoshi; Yamaguchi, Takao; Itano, Keita; Hibiya, Yuki; Suzuki, Kazue

2017-03-01

The 176Lu-176Hf radioactive decay system has been widely used to study planetary crust-mantle differentiation. Of considerable utility in this regard is zircon, a resistant mineral that can be precisely dated by the U-Pb chronometer and record its initial Hf isotope composition due to having low Lu/Hf. Here we review zircon U-Pb age and Hf isotopic data mainly obtained over the last two decades and discuss their contributions to our current understanding of crust-mantle evolution, with emphasis on the Lu-Hf isotope composition of the bulk silicate Earth (BSE), early differentiation of the silicate Earth, and the evolution of the continental crust over geologic history. Meteorite zircon encapsulates the most primitive Hf isotope composition of our solar system, which was used to identify chondritic meteorites best representative of the BSE (176Hf/177Hf = 0.282793 ± 0.000011; 176Lu/177Hf = 0.0338 ± 0.0001). Hadean-Eoarchean detrital zircons yield highly unradiogenic Hf isotope compositions relative to the BSE, providing evidence for the development of a geochemically enriched silicate reservoir as early as 4.5 Ga. By combining the Hf and O isotope systematics, we propose that the early enriched silicate reservoir has resided at depth within the Earth rather than near the surface and may represent a fractionated residuum of a magma ocean underlying the proto-crust, like urKREEP beneath the anorthositic crust on the Moon. Detrital zircons from world major rivers potentially provide the most robust Hf isotope record of the preserved granitoid crust on a continental scale, whereas mafic rocks with various emplacement ages offer an opportunity to trace the Hf isotope evolution of juvenile continental crust (from εHf[4.5 Ga] = 0 to εHf[present] = + 13). The river zircon data as compared to the juvenile crust composition highlight that the supercontinent cycle has controlled the evolution of the continental crust by regulating the rates of crustal generation and intra-crustal reworking processes and the preservation potential of granitoid crust. We use the data to explore the timing of generation of the preserved continental crust. Taking into account the crustal residence times of continental crust recycled back into the mantle, we further propose a model of net continental growth that stable continental crust was firstly established in the Paleo- and Mesoarchean and significantly grew in the Paleoproterozoic.

Inter-individual Differences in Heart Rate Variability Are Associated with Inter-individual Differences in Empathy and Alexithymia.

PubMed

Lischke, Alexander; Pahnke, Rike; Mau-Moeller, Anett; Behrens, Martin; Grabe, Hans J; Freyberger, Harald J; Hamm, Alfons O; Weippert, Matthias

2018-01-01

In the present study, we investigated whether inter-individual differences in vagally mediated heart rate variability (vmHRV) would be associated with inter-individual differences in empathy and alexithymia. To this end, we determined resting state HF-HRV in 90 individuals that also completed questionnaires assessing inter-individual differences in empathy and alexithymia. Our categorical and dimensional analyses revealed that inter-individual differences in HF-HRV were differently associated with inter-individual differences in empathy and alexithymia. We found that individuals with high HF-HRV reported more empathy and less alexithymia than individuals with low HF-HRV. Moreover, we even found that an increase in HF-HRV was associated with an increase in empathy and a decrease in alexithymia across all participants. Taken together, these findings indicate that individuals with high HF-HRV are more empathetic and less alexithymic than individuals with low HF-HRV. These differences in empathy and alexithymia may explain why individuals with high HF-HRV are more successful in sharing and understanding the mental and emotional states of others than individuals with low HF-HRV.

A reevaluation of the costs of heart failure and its implications for allocation of health resources in the United States.

PubMed

Voigt, Jeff; Sasha John, M; Taylor, Andrew; Krucoff, Mitchell; Reynolds, Matthew R; Michael Gibson, C

2014-05-01

The annual cost of heart failure (HF) is estimated at $39.2 billion. This has been acknowledged to underestimate the true costs for care. The objective of this analysis is to more accurately assess these costs. Publicly available data sources were used. Cost calculations incorporated relevant factors such as Medicare hospital cost-to-charge ratios, reimbursement from both government and private insurance, and out-of-pocket expenditures. A recently published Atherosclerosis Risk in Communities (ARIC) HF scheme was used to adjust the HF classification scheme. Costs were calculated with HF as the primary diagnosis (HF in isolation, or HFI) or HF as one of the diagnoses/part of a disease milieu (HF syndrome, or HFS). Total direct costs for HF were calculated at $60.2 billion (HFI) and $115.4 billion (HFS). Indirect costs were $10.6 billion for both. Costs attributable to HF may represent a much larger burden to US health care than what is commonly referenced. These revised and increased costs have implications for policy makers.

PATHOPHYSIOLOGY AND THE CARDIORENAL CONNECTION IN HEART FAILURE. CIRCULATING HORMONES: BIOMARKERS OR MEDIATORS

PubMed Central

BUGLIONI, ALESSIA; BURNETT, JOHN C.

2014-01-01

Heart failure (HF) is a syndrome characterized by a complex pathophysiology which involves multiple organ systems, with the kidney playing a major role. HF can present with reduced ejection fraction (EF), HFrEF, or with preserved EF (HFpEF). The interplay between diverse organ systems contributing to HF is mediated by the activation of counteracting neurohormonal pathways focused to re-establishing hemodynamic homeostasis. During early stages of HF, these biochemical signals, consisting mostly of hormones and neurotransmitters secreted by a variety of cell types, are compensatory and the patient is asymptomatic. However, with disease progression, the attempt to reverse or delay cardiac dysfunction is deleterious, leading to multi-organ congestion, fibrosis and decompensation and finally symptomatic HF. In conclusion, these neurohormonal pathways mediate the evolution of HF and have become a way to monitor HF. Specifically, these mediators have become important in the diagnosis and prognosis of this highly fatal cardiovascular disease. Finally, while these multiple neurohumoral factors serve as important HF biomarkers, they can also be targeted for more effective and curative HF treatments. PMID:25445413

Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}: Two stannide intermetallics with low-dimensional iron sublattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calta, Nicholas P.; Kanatzidis, Mercouri G., E-mail: m-kanatzidis@northwestern.edu; Materials Science Division, Argonne National Laboratory

This article reports two new Hf-rich intermetallics synthesized using Sn flux: Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}. Hf{sub 3}Fe{sub 4}Sn{sub 4} adopts an ordered variant the Hf{sub 3}Cu{sub 8} structure type in orthorhombic space group Pnma with unit cell edges of a=8.1143(5) Å, b=8.8466(5) Å, and c=10.6069(6) Å. Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}, on the other hand, adopts a new structure type in Cmc2{sub 1} with unit cell edges of a=5.6458(3) Å, b=35.796(2) Å, and c=8.88725(9) Å for x=0. It exhibits a small amount of phase width in which Sn substitutes on one of the Fe sites. Bothmore » structures are fully three-dimensional and are characterized by pseudo one- and two-dimensional networks of Fe–Fe homoatomic bonding. Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} exhibits antiferromagnetic order at T{sub N}=46(2) K and its electrical transport behavior indicates that it is a normal metal with phonon-dictated resistivity. Hf{sub 3}Fe{sub 4}Sn{sub 4} is also an antiferromagnet with a rather high ordering temperature of T{sub N}=373(5) K. Single crystal resistivity measurements indicate that Hf{sub 3}Fe{sub 4}Sn{sub 4} behaves as a Fermi liquid at low temperatures, indicating strong electron correlation. - Graphical abstract: Slightly different growth conditions in Sn flux produce two new intermetallic compounds: Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x}. - Highlights: • Single crystals of both Hf{sub 3}Fe{sub 4}Sn{sub 4} and Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} were grown using Sn flux. • The crystal structures were determined using single crystal X-ray diffraction. • The Fe moments in Hf{sub 3}Fe{sub 4}Sn{sub 4} display AFM order below T{sub N}=373 K. • The Fe moments in Hf{sub 9}Fe{sub 4−x}Sn{sub 10+x} display AFM order below T{sub N}=46 K.« less

Halofuginone suppresses growth of human uterine leiomyoma cells in a mouse xenograft model.

PubMed

Koohestani, Faezeh; Qiang, Wenan; MacNeill, Amy L; Druschitz, Stacy A; Serna, Vanida A; Adur, Malavika; Kurita, Takeshi; Nowak, Romana A

2016-07-01

Does halofuginone (HF) inhibit the growth of human uterine leiomyoma cells in a mouse xenograft model? HF suppresses the growth of human uterine leiomyoma cells in a mouse xenograft model through inhibiting cell proliferation and inducing apoptosis. Uterine leiomyomas are the most common benign tumors of the female reproductive tract. HF can suppress the growth of human uterine leiomyoma cells in vitro. The mouse xenograft model reflects the characteristics of human leiomyomas. Primary leiomyoma smooth muscle cells from eight patients were xenografted under the renal capsule of adult, ovariectomized NOD-scid IL2Rγ(null) mice (NSG). Mice were treated with two different doses of HF or vehicle for 4 weeks with six to eight mice per group. Mouse body weight measurements and immunohistochemical analysis of body organs were carried out to assess the safety of HF treatment. Xenografted tumors were measured and analyzed for cellular and molecular changes induced by HF. Ovarian steroid hormone receptors were evaluated for possible modulation by HF. Treatment of mice carrying human UL xenografts with HF at 0.25 or 0.50 mg/kg body weight for 4 weeks resulted in a 35-40% (P < 0.05) reduction in tumor volume. The HF-induced volume reduction was accompanied by increased apoptosis and decreased cell proliferation. In contrast, there was no significant change in the collagen content either at the transcript or protein level between UL xenografts in control and HF groups. HF treatment did not change the expression level of ovarian steroid hormone receptors. No adverse pathological effects were observed in other tissues from mice undergoing treatment at these doses. While this study did test the effects of HF on human leiomyoma cells in an in vivo model, HF was administered to mice whose tolerance and metabolism of the drug may differ from that in humans. Also, the longer term effects of HF treatment are yet unclear. The results of this study showing the effectiveness of HF in reducing UL tumor growth by interfering with the main cellular processes regulating cell proliferation and apoptosis are in agreement with previous studies on the effects of HF on other fibrotic diseases. HF can be considered as a candidate for reducing the size of leiomyomas, particularly prior to surgery. This project was funded by NIH PO1HD057877 and R01 HD064402. Authors report no competing interests. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, Thomas J.; Myjak, Mitchell J.

At the request of the U.S. Army Corps of Engineers, Portland District, researchers from Pacific Northwest National Laboratory investigated the use of an application-specific integrated circuit (ASIC) to reduce the weight and volume of Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters while retaining current functionality. Review of the design of current JSATS transmitters identified components that could be replaced by an ASIC while retaining the function of the current transmitter and offering opportunities to extend function if desired. ASIC design alternatives were identified that could meet transmitter weight and volume targets of 200 mg and 100 mm3. If alternatives tomore » the cylindrical batteries used in current JSATS transmitters can be identified, it could be possible to implant ASIC-based JSATS transmitters by injection rather than surgery. Using criteria for the size of fish suitable for surgical implantation of current JSATS transmitters, it was concluded that fish as small as 70 mm in length could be implanted with an ASIC-based transmitter, particularly if implantation by injection became feasible.« less

Effect of relative volume on radio transmitter expulsion in subadult common carp

USGS Publications Warehouse

Penne, C.R.; Ahrens, N.L.; Summerfelt, R.C.; Pierce, C.L.

2007-01-01

Expulsion of surgically implanted radio transmitters is a problem in some fish telemetry studies. We conducted a 109-d experiment to test the hypothesis that variation in relative volume of transmitters surgically implanted in subadult common carp Cyprinus carpio would affect transmitter expulsion. We also necropsied fish at the end of the experiment to evaluate histological evidence for the mechanism of expulsion. Survival rate was high during our experiment; all control fish and 88% of the fish subjected to the implantation surgery survived. Expulsion rate was low; of the 23 fish that received transmitters and survived the experiment, only two (9%) expelled the transmitters. One of these expulsions occurred through a rupture of the incision and the other occurred via the intestine. Retained transmitters were all encapsulated by tissue, and most exhibited multiple adhesions to the intestine, gonads, and body wall. Adhesions were more numerous in fish that received larger transmitters. ?? Copyright by the American Fisheries Society 2007.

Predictive value of high sensitivity CRP in patients with diastolic heart failure.

PubMed

Michowitz, Yoav; Arbel, Yaron; Wexler, Dov; Sheps, David; Rogowski, Ori; Shapira, Itzhak; Berliner, Shlomo; Keren, Gad; George, Jacob; Roth, Arie

2008-04-25

C-reactive protein (CRP) has been tested in patients with systolic heart failure (HF) and mixed results have been obtained with regards to its potential predictive value. However, the role of C-reactive protein (CRP) in patients with diastolic HF is not established. We studied the predictive role of high sensitivity CRP (hsCRP) in patients with diastolic HF. HsCRP levels were measured in a cohort of CHF outpatients, 77 patients with diastolic HF and 217 patients with systolic HF. Concentrations were compared to a large cohort of healthy population (n=7701) and associated with the HF admissions and mortality of the patients. Levels of hsCRP did not differ between patients with systolic and diastolic HF and were significantly elevated compared to the cohort of healthy subjects even after adjustment to various clinical parameters (p<0.0001). In patients with diastolic HF, hsCRP levels associated with New York Heart Association functional class (NYHA-FC) (r=0.31 p=0.01). On univariate Cox regression model hsCRP levels independently predicted hospitalizations in patients with systolic but not diastolic HF (p=0.047). HsCRP concentrations are elevated in patients with diastolic HF and correlate with disease severity; their prognostic value in this patient population should be further investigated.

QishenYiqi Dripping Pill Improves Heart Failure by Up-Regulation of β2-Adrenergic Receptor Expression.

PubMed

Sun, Junfeng; Qian, Hua; Li, Xiaoguang; Tang, Xianling

2017-03-01

QishenYiqi Dripping Pill (QYDP) is a Chinese herbal medicine that originally was used for the treatment of coronary artery disease. Recently, QYDP was used as a complementary treatment for heart failure (HF) in China. An HF rat model was used to clarify the possible therapeutic effects of QYDP on HF. The HF rats were allocated to two groups, HF and HF+QYDP, while normal rats served as a negative control. Cardiac functions were evaluated echocardiographically and hemodynamically. Cardiac apoptosis and the expression of β-adrenergic receptors were also investigated. Compared to the HF group, rats in the HF+QYDP group had a significantly higher fraction shortening (p<0.05), ejection fraction (p<0.05), left ventricular systolic pressure (p<0.05), maximum positive derivatives of left ventricular pressure (p<0.05), maximum negative derivatives of left ventricular pressure (p<0.05), and β2-adrenergic receptor expression (p<0.05), and lower left ventricular end-diastolic pressure (p<0.05) and apoptotic index (p<0.05). The study results indicated that QYDP could efficiently improve HF, possibly by an inhibition of cardiac apoptosis via the β2-adrenergic receptor signaling pathway. Hence, QYDP might be a promising candidate drug for HF therapy.

Differentiation of hepatocytes from induced pluripotent stem cells derived from human hair follicle mesenchymal stem cells.

PubMed

Shi, Xu; Lv, Shuang; He, Xia; Liu, Xiaomei; Sun, Meiyu; Li, Meiying; Chi, Guangfan; Li, Yulin

2016-10-01

Due to the limitations of organ donors and immune rejection in severe liver diseases, stem cell-based therapy presents a promising application for tissue repair and regeneration. As a novel cell source, mesenchymal stem cells separated from human hair follicles (HF-MSCs) are convenient to obtain and have no age limit. To date, the differentiation of HF-MSCs into hepatocytes has not been reported. In this study, we explored whether HF-MSCs and HF-MSC-derived-induced pluripotent stem cells (HF-iPS) could differentiate into hepatocytes in vitro. Flow cytometry, Oil Red O stain and Alizarin Red stain were used to identify the characteristics of HF-MSCs. The expression of liver-specific gene was detected by immunofluorescence and Quantitative Polymerase Chain Reaction. Periodic Acid-Schiff stain, Indocyanine Green stain and Low-Density Lipoprotein stain were performed to evaluate the functions of induced hepatocyte-like cells (HLCs). HF-MSCs were unable to differentiate into HLCs using previously reported procedures for MSCs from other tissues. However, HF-iPS efficiently induced the generation of HLCs that expressed hepatocyte markers and drug metabolism-related genes. HF-iPS can be used as novel and alternative cellular tools for inducing hepatocytes in vitro, simultaneously benefiting from utilizing HF-MSCs as a noninvasive and convenient cell source for reprogramming.

The effect of adaptive servo ventilation (ASV) on objective and subjective outcomes in Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF): A systematic review.

PubMed

Yang, Hyunju; Sawyer, Amy M

2016-01-01

To summarize the current evidence for adaptive servo ventilation (ASV) in Cheyne-Stokes respiration (CSR) with central sleep apnea (CSA) in heart failure (HF) and advance a research agenda and clinical considerations for ASV-treated CSR-CSA in HF. CSR-CSA in HF is associated with higher overall mortality, worse outcomes and lower quality of life (QOL) than HF without CSR-CSA. Five databases were searched using key words (n = 234). Randomized controlled trials assessed objective sleep quality, cardiac, and self-reported outcomes in adults (≥18 years) with HF (n = 10). ASV has a beneficial effect on the reduction of central sleep apnea in adult patients with CSR-CSA in HF, but it is not be superior to CPAP, bilevel PPV, or supplemental oxygen in terms of sleep quality defined by polysomnography, cardiovascular outcomes, subjective daytime sleepiness, and quality of life. ASV is not recommended for CSR-CSA in HF. It is important to continue to refer HF patients for sleep evaluation to clearly discern OSA from CSR-CSA. Symptom management research, inclusive of objective and subjective outcomes, in CSR-CSA in HF adults is needed. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of the annealing temperature and ion-beam bombardment on the properties of solution-derived HfYGaO films as liquid crystal alignment layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Hong-Gyu; Lee, Yun-Gun; Jang, Sang Bok

2015-11-15

Hafnium yttrium gallium oxide (HfYGaO) films were applied to liquid crystal displays (LCDs) as liquid crystal (LC) alignment layers, replacing conventional polyimide (PI) layers. The HfYGaO alignment layers were prepared by fabricating solution-processed HfYGaO films, annealing them, and treating them with ion-beam (IB) irradiation. The authors studied the effects of annealing temperature and IB irradiation of the solution-derived HfYGaO films on the orientation of LC molecules. The LC molecules on the solution-derived HfYGaO films were homogeneously and uniformly aligned by IB irradiation, irrespective of the annealing temperature. Atomic force microscopy analyses revealed that the surface reformation of the HfYGaO filmsmore » induced by IB irradiation strengthened the van der Waals force between the LC molecules and the HfYGaO films, leading to uniform LC alignment. Enhanced electro-optical characteristics were observed in the twisted-nematic (TN) LCDs based on IB-irradiated HfYGaO films compared with those of TN-LCDs based on PI layers, demonstrating the high application potential of the proposed solution-derived HfYGaO films as LC alignment layers.« less

The Palliative Care in Heart Failure (PAL-HF) Trial: Rationale and Design

PubMed Central

Mentz, Robert J.; Tulsky, James A.; Granger, Bradi B.; Anstrom, Kevin J.; Adams, Patricia A.; Dodson, Gwen C.; Fiuzat, Mona; Johnson, Kimberly S.; Patel, Chetan B.; Steinhauser, Karen E.; Taylor, Donald H.; O’Connor, Christopher M.; Rogers, Joseph G.

2014-01-01

Background The progressive nature of heart failure (HF) coupled with high mortality and poor quality of life mandates greater attention to palliative care as a routine component of advanced HF management. Limited evidence exists from randomized, controlled trials supporting the use of interdisciplinary palliative care in HF. Methods The Palliative Care in Heart Failure trial (PAL-HF) is a prospective, controlled, unblinded, single-center study of an interdisciplinary palliative care intervention in 200 patients with advanced HF estimated to have a high likelihood of mortality or re-hospitalization in the ensuing 6 months. The 6-month PAL-HF intervention focuses on physical and psychosocial symptom relief, attention to spiritual concerns and advanced care planning. The primary endpoint is health-related quality of life measured by the Kansas City Cardiomyopathy Questionnaire and the Functional Assessment of Chronic Illness Therapy with Palliative Care Subscale score at 6 months. Secondary endpoints include changes in anxiety/depression, spiritual well-being, caregiver satisfaction, cost and resource utilization, and a composite of death, HF hospitalization and quality of life. Conclusions PAL-HF is a randomized, controlled clinical trial that will help evaluate the efficacy and cost-effectiveness of palliative care in advanced HF using a patient-centered outcome as well as clinical and economic endpoints. PMID:25440791

The Juvenile Hafnium Isotope Signal as a Record of Supercontinent Cycles

PubMed Central

Gardiner, Nicholas J.; Kirkland, Christopher L.; Van Kranendonk, Martin J.

2016-01-01

Hf isotope ratios measured in igneous zircon are controlled by magmatic source, which may be linked to tectonic setting. Over the 200–500 Myr periodicity of the supercontinent cycle - the principal geological phenomenon controlling prevailing global tectonic style - juvenile Hf signals, i.e. most radiogenic, are typically measured in zircon from granites formed in arc settings (crustal growth), and evolved zircon Hf signals in granites formed in continent-collision settings (crustal reworking). Interrogations of Hf datasets for excursions related to Earth events commonly use the median value, however this may be equivocal due to magma mixing. The most juvenile part of the Hf signal is less influenced by crustal in-mixing, and arguably a more sensitive archive of Earth’s geodynamic state. We analyze the global Hf dataset for this juvenile signal, statistically correlating supercontinent amalgamation intervals with evolved Hf episodes, and breakup leading to re-assembly with juvenile Hf episodes. The juvenile Hf signal is more sensitive to Pangaea and Rodinia assembly, its amplitude increasing with successive cycles to a maximum with Gondwana assembly which may reflect enhanced subduction-erosion. We demonstrate that the juvenile Hf signal carries important information on prevailing global magmatic style, and thus tectonic processes. PMID:27924946

Effect of exercise and caloric restriction on DMBA induced mammary tumorigenesis and plasma lipids in rats fed high fat diets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magrane, D.

1991-03-15

Female Sprague-Dawley rats were given a single 10 mg dose of 7, 12-Dimethylbenz(a)anthracene (DMBA) and grouped as follows: (1) low fat-sedentary (LF-SED), (2) low fat-exercised (LF-EX), (3) high fat-sedentary (HF-SED), (4) high fat-exercised (HF-EX), (5) high fat-caloric restricted (HF-RES). Diets were isocaloric and contained 3.9% (LF) and 19.4% (HF) of corn oil. Group 5 was fed a 25% caloric restricted diet but with 24.6% fat content to equalize fat intake to HF-SED. After 12 weeks of diet or treadmill exercise, tumor data and plasma lipid profiles were determined. Results show that rats on HF-EX had more total tumors, % ofmore » tumors and tumors per tumor bearing rat than rats on HF-SED. The effect of exercise was also evident in LF-EX rats, when compared to LF-SED. Average tumor size and tumor volumes were not affected. The HF-RES group showed reduced tumor profiles compared to HF-SED. HDL, LDL, triglycerides and total cholesterol were unaffected by HF or LF diets or exercise. These data suggest that tumorigenesis is increased by moderate and constant exercise.« less

Use of oviduct-inserted acoustic transmitters and positional telemetry to estimate timing and location of spawning: a feasibility study in lake trout, Salvelinus namaycush

USGS Publications Warehouse

Binder, Thomas R.; Holbrook, Christopher M.; Miehls, Scott M.; Thompson, Henry T.; Krueger, Charles C.

2014-01-01

Our results satisfied the three assumptions of oviduct tagging and suggested that oviduct transmitters can be used with positional telemetry to estimate time and location of spawning in lake trout and other species. In situations where oviduct transmitters may be difficult to position once expelled into substrate, pairing oviduct transmitters with a normal-sized fish transmitter that remains in the fish is recommended, with spawning inferred when the two tags separate in space. Optimal transmitter delay will depend on expected degree of spawning site residency and swim speed.

Transmittance and Tunneling Current through a Trapezoidal Barrier under Spin Polarization Consideration

NASA Astrophysics Data System (ADS)

Noor, F. A.; Nabila, E.; Mardianti, H.; Ariani, T. I.; Khairurrijal

2018-04-01

The transmittance and tunneling current in heterostructures under spin polarization consideration were studied by employing a zinc-blended structure for the heterostructures. An electron tunnels through a potential barrier by applying a bias voltage to the barrier, which is called the trapezoidal potential barrier. In order to study the transmittance, an Airy wave function approach was employed to find the transmittance. The obtained transmittance was then utilized to compute the tunneling current by using a Gauss quadrature method. It was shown that the transmittances were asymmetric with the incident angle of the electron. It was also shown that the tunneling currents increased as the bias voltage increased.

Empirical Study of the Multiaxial, Thermomechanical Behavior of NiTiHf Shape Memory Alloys

NASA Technical Reports Server (NTRS)

Shukla, Dhwanil; Noebe, Ronald D.; Stebner Aaron P.

2013-01-01

An empirical study was conducted to characterize the multiaxial, thermomechanical responses of new high temperature NiTiHf alloys. The experimentation included loading thin walled tube Ni(sub 50.3)Ti(sub 29.7)Hf(sub 20) alloy samples along both proportional and nonproportional axial-torsion paths at different temperatures while measuring surface strains using stereo digital image correlation. A Ni(sub 50.3)Ti(sub 33.7)Hf(sub 16) alloy was also studied in tension and compression to document the effect of slightly depleting the Hf content on the constitutive responses of NiTiHf alloys. Samples of both alloys were made from nearly texture free polycrystalline material processed by hot extrusion. Analysis of the data shows that very small changes in composition significantly alter NiTiHf alloy properties, as the austenite finish (Af) temperature of the 16-at Hf alloy was found to be approximately 60 C less than the 20-at Hf alloy (approximately 120 C vs. 180 C). In addition, the 16-at Hf alloy exhibited smaller compressive transformation strains (2 vs. 2.5 percent). Multi-axial characterization of the 20-at % Hf alloy showed that while the random polycrystal transformation strains in tension (4 percent) and compression (2.5 percent) are modest in comparison with binary NiTi (6 percent, 4 percent), the torsion performance is superior (7 vs. 4 shear strain width to the pseudoelastic plateau).

Hf 3 Fe 4 Sn 4 and Hf 9 Fe 4-x Sn 10+x : Two stannide intermetallics with low-dimensional iron sublattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calta, Nicholas P.; Kanatzidis, Mercouri G.

2016-04-01

This article reports two new Hf-rich intermetallics synthesized using Sn flux: Hf 3Fe 4Sn 4 and Hf 9Fe 4-xSn 10+x. Hf 3Fe 4Sn 4 adopts an ordered variant the Hf 3Cu 8 structure type in orthorhombic space group Pnma with unit cell edges of a=8.1143(5) Å, b=8.8466(5) Å, and c=10.6069(6) Å. Hf 9Fe 4-xSn 10+x, on the other hand, adopts a new structure type in Cmc21 with unit cell edges of a=5.6458(3) Å, b=35.796(2) Å, and c=8.88725(9) Å for x=0. It exhibits a small amount of phase width in which Sn substitutes on one of the Fe sites. Both structuresmore » are fully three-dimensional and are characterized by pseudo one- and two-dimensional networks of Fe–Fe homoatomic bonding. Hf 9Fe 4-xSn 10+x exhibits antiferromagnetic order at TN=46(2) K and its electrical transport behavior indicates that it is a normal metal with phonon-dictated resistivity. Hf 3Fe 4Sn 4 is also an antiferromagnet with a rather high ordering temperature of TN=373(5) K. Single crystal resistivity measurements indicate that Hf 3Fe 4Sn 4 behaves as a Fermi liquid at low temperatures, indicating strong electron correlation.« less

Structure and properties of a model conductive filament/host oxide interface in HfO2-based ReRAM

NASA Astrophysics Data System (ADS)

Padilha, A. C. M.; McKenna, K. P.

2018-04-01

Resistive random-access memory (ReRAM) is a promising class of nonvolatile memory capable of storing information via its resistance state. In the case of hafnium oxide-based devices, experimental evidence shows that a conductive oxygen-deficient filament is formed and broken inside of the device by oxygen migration, leading to switching of its resistance state. However, little is known about the nature of this conductive phase, its interface with the host oxide, or the associated interdiffusion of oxygen, presenting a challenge to understanding the switching mechanism and device properties. To address these problems, we present atomic-scale first-principles simulations of a prototypical conductive phase (HfO), the electronic properties of its interface with HfO2, as well as stability with respect to oxygen diffusion across the interface. We show that the conduction-band offset between HfO and HfO2 is 1.3 eV, smaller than typical electrode-HfO2 band offsets, suggesting that positive charging and band bending should occur at the conductive filament-HfO2 interface. We also show that transfer of oxygen across the interface, from HfO2 into HfO, costs around 1.2 eV per atom and leads to a gradual opening of the HfO band gap, and hence disruption of the electrical conductivity. These results provide invaluable insights into understanding the switching mechanism for HfO2-based ReRAM.

Evaluation of Quality of Life in Patients with and without Heart Failure in Primary Care.

PubMed

Jorge, Antonio José Lagoeiro; Rosa, Maria Luiza Garcia; Correia, Dayse Mary da Silva; Martins, Wolney de Andrade; Ceron, Diana Maria Martinez; Coelho, Leonardo Chaves Ferreira; Soussume, William Shinji Nobre; Kang, Hye Chung; Moscavitch, Samuel Datum; Mesquita, Evandro Tinoco

2017-09-01

Heart failure (HF) is a major public health issue with implications on health-related quality of life (HRQL). To compare HRQL, estimated by the Short-Form Health Survey (SF-36), in patients with and without HF in the community. Cross-sectional study including 633 consecutive individuals aged 45 years or older, registered in primary care. The subjects were selected from a random sample representative of the population studied. They were divided into two groups: group I, HF patients (n = 59); and group II, patients without HF (n = 574). The HF group was divided into HF with preserved ejection fraction (HFpEF - n = 35) and HF with reduced ejection fraction (HFrEF - n = 24). Patients without HF had a mean SF-36 score significantly greater than those with HF (499.8 ± 139.1 vs 445.4 ± 123.8; p = 0.008). Functional capacity - ability and difficulty to perform common activities of everyday life - was significantly worse (p < 0.0001) in patients with HF independently of sex and age. There was no difference between HFpEF and HFrEF. Patients with HF had low quality of life regardless of the syndrome presentation (HFpEF or HFrEF phenotype). Quality of life evaluation in primary care could help identify patients who would benefit from a proactive care program with more emphasis on multidisciplinary and social support. (Arq Bras Cardiol. 2017; [online].ahead print, PP.0-0).

47 CFR 22.809 - Transmitting power limits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Transmitting power limits. The transmitting power of ground and airborne mobile transmitters operating on the... Watts, except as provided in § 22.811. (b) Airborne mobile transmitters. The transmitter power output of airborne mobile transmitters must not exceed 25 Watts and must not be less than 4 Watts. ...

47 CFR 101.513 - Transmitter power.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis demonstrating...

47 CFR 22.1013 - Effective radiated power limitations.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... The effective radiated power (ERP) of transmitters in the Offshore Radiotelephone Service must not exceed the limits in this section. (a) Maximum power. The ERP of transmitters in this service must not exceed 1000 Watts under any circumstances. (b) Mobile transmitters. The ERP of mobile transmitters must...

47 CFR 73.315 - FM transmitter location.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false FM transmitter location. 73.315 Section 73.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.315 FM transmitter location. (a) The transmitter location shall be chosen so that...

47 CFR 73.315 - FM transmitter location.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false FM transmitter location. 73.315 Section 73.315 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES FM Broadcast Stations § 73.315 FM transmitter location. (a) The transmitter location shall be chosen so that...

47 CFR 101.513 - Transmitter power.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 5 2011-10-01 2011-10-01 false Transmitter power. 101.513 Section 101.513... SERVICES 24 GHz Service and Digital Electronic Message Service § 101.513 Transmitter power. The transmitter power will be governed by § 101.113. Further, each application must contain an analysis demonstrating...

47 CFR 22.507 - Number of transmitters per station.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 2 2012-10-01 2012-10-01 false Number of transmitters per station. 22.507... PUBLIC MOBILE SERVICES Paging and Radiotelephone Service § 22.507 Number of transmitters per station. This section concerns the number of transmitters licensed under each station authorization in the...

Lessons learned in acute heart failure.

PubMed

Cheema, Baljash; Ambrosy, Andrew P; Kaplan, Rachel M; Senni, Michele; Fonarow, Gregg C; Chioncel, Ovidiu; Butler, Javed; Gheorghiade, Mihai

2018-04-01

Acute heart failure (HF) is a global pandemic with more than one million admissions to hospital annually in the US and millions more worldwide. Post-discharge mortality and readmission rates remain unchanged and unacceptably high. Although recent drug development programmes have failed to deliver novel therapies capable of reducing cardiovascular morbidity and mortality in patients hospitalized for worsening chronic HF, hospitalized HF registries and clinical trial databases have generated a wealth of information improving our collective understanding of the HF syndrome. This review will summarize key insights from clinical trials in acute HF and hospitalized HF registries over the last several decades, focusing on improving the management of patients with HF and reduced ejection fraction. © 2017 The Authors. European Journal of Heart Failure © 2017 European Society of Cardiology.

Comparison of spontaneous vs. metronome-guided breathing on assessment of vagal modulation using RR variability.

PubMed

Bloomfield, D M; Magnano, A; Bigger, J T; Rivadeneira, H; Parides, M; Steinman, R C

2001-03-01

R-R interval variability (RR variability) is increasingly being used as an index of autonomic activity. High-frequency (HF) power reflects vagal modulation of the sinus node. Since vagal modulation occurs at the respiratory frequency, some investigators have suggested that HF power cannot be interpreted unless the breathing rate is controlled. We hypothesized that HF power during spontaneous breathing would not differ significantly from HF power during metronome-guided breathing. We measured HF power during spontaneous breathing in 20 healthy subjects and 19 patients with heart disease. Each subject's spontaneous breathing rate was determined, and the calculation of HF power was repeated with a metronome set to his or her average spontaneous breathing rate. There was no significant difference between the logarithm of HF power measured during spontaneous and metronome-guided breathing [4.88 +/- 0.29 vs. 5.29 +/- 0.30 ln(ms(2)), P = 0.32] in the group as a whole and when patients and healthy subjects were examined separately. We did observe a small (9.9%) decrease in HF power with increasing metronome-guided breathing rates (from 9 to 20 breaths/min). These data indicate that HF power during spontaneous and metronome-guided breathing differs at most by very small amounts. This variability is several logarithmic units less than the wide discrepancies observed between healthy subjects and cardiac patients with a heterogeneous group of cardiovascular disorders. In addition, HF power is relatively constant across the range of typical breathing rates. These data indicate that there is no need to control breathing rate to interpret HF power when RR variability (and specifically HF power) is used to identify high-risk cardiac patients.

Renal dysfunction in patients with heart failure with preserved versus reduced ejection fraction: impact of the new Chronic Kidney Disease-Epidemiology Collaboration Group formula.

PubMed

McAlister, Finlay A; Ezekowitz, Justin; Tarantini, Luigi; Squire, Iain; Komajda, Michel; Bayes-Genis, Antoni; Gotsman, Israel; Whalley, Gillian; Earle, Nikki; Poppe, Katrina K; Doughty, Robert N

2012-05-01

Prior studies in heart failure (HF) have used the Modification of Diet in Renal Disease (MDRD) equation to calculate estimated glomerular filtration rate (eGFR). The Chronic Kidney Disease-Epidemiology Collaboration Group (CKD-EPI) equation provides a more-accurate eGFR than the MDRD when compared against the radionuclide gold standard. The prevalence and prognostic import of renal dysfunction in HF if the CKD-EPI equation is used rather than the MDRD is uncertain. We used individual patient data from 25 prospective studies to stratify patients with HF by eGFR using the CKD-EPI and the MDRD equations and examined survival across eGFR strata. In 20 754 patients (15 962 with HF with reduced ejection fraction [HF-REF] and 4792 with HF with preserved ejection fraction [HF-PEF]; mean age, 68 years; deaths per 1000 patient-years, 151; 95% CI, 146-155), 10 589 (51%) and 11 422 (55%) had an eGFR <60 mL/min using the MDRD and CKD-EPI equations, respectively. Use of the CKD-EPI equation resulted in 3760 (18%) patients being reclassified into different eGFR risk strata; 3089 (82%) were placed in a lower eGFR category and exhibited higher all-cause mortality rates (net reclassification improvement with CKD-EPI, 3.7%; 95% CI, 1.5%-5.9%). Reduced eGFR was a stronger predictor of all-cause mortality in HF-REF than in HF-PEF. Use of the CKD-EPI rather than the MDRD equation to calculate eGFR leads to higher estimates of renal dysfunction in HF and a more-accurate categorization of mortality risk. Renal function is more closely related to outcomes in HF-REF than in HF-PEF.

Differing prognostic value of pulse pressure in patients with heart failure with reduced or preserved ejection fraction: results from the MAGGIC individual patient meta-analysis.

PubMed

Jackson, Colette E; Castagno, Davide; Maggioni, Aldo P; Køber, Lars; Squire, Iain B; Swedberg, Karl; Andersson, Bert; Richards, A Mark; Bayes-Genis, Antoni; Tribouilloy, Christophe; Dobson, Joanna; Ariti, Cono A; Poppe, Katrina K; Earle, Nikki; Whalley, Gillian; Pocock, Stuart J; Doughty, Robert N; McMurray, John J V

2015-05-07

Low pulse pressure is a marker of adverse outcome in patients with heart failure (HF) and reduced ejection fraction (HF-REF) but the prognostic value of pulse pressure in patients with HF and preserved ejection fraction (HF-PEF) is unknown. We examined the prognostic value of pulse pressure in patients with HF-PEF [ejection fraction (EF) ≥ 50%] and HF-REF. Data from 22 HF studies were examined. Preserved left ventricular ejection fraction (LVEF) was defined as LVEF ≥ 50%. All-cause mortality at 3 years was evaluated in 27 046 patients: 22 038 with HF-REF (4980 deaths) and 5008 with HF-PEF (828 deaths). Pulse pressure was analysed in quintiles in a multivariable model adjusted for the previously reported Meta-Analysis Global Group in Chronic Heart Failure prognostic variables. Heart failure and reduced ejection fraction patients in the lowest pulse pressure quintile had the highest crude and adjusted mortality risk (adjusted hazard ratio 1.68, 95% confidence interval 1.53-1.84) compared with all other pulse pressure groups. For patients with HF-PEF, higher pulse pressure was associated with the highest crude mortality, a gradient that was eliminated after adjustment for other prognostic variables. Lower pulse pressure (especially <53 mmHg) was an independent predictor of mortality in patients with HF-REF, particularly in those with an LVEF < 30% and systolic blood pressure <140 mmHg. Overall, this relationship between pulse pressure and outcome was not consistently observed among patients with HF-PEF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Plasma urocortin in human systolic heart failure.

PubMed

Ng, Leong L; Loke, Ian W; O'Brien, Russell J; Squire, Iain B; Davies, Joan E

2004-04-01

Urocortin (UCN), a member of the corticotrophin-releasing factor family, is expressed in heart, brain and gut. UCN has potent cardiostimulatory, cardioprotective, vasodilator and diuretic/natriuretic effects, and cardiac UCN expression is increased in heart failure (HF). In the present study, we investigated plasma levels of UCN in 119 patients with HF and 212 age- and gender-matched controls to clarify its relationship with gender and disease severity. UCN was elevated in HF [normal males, 19.5 (3.9-68.8) pmol/l and HF males, 50.2 (6.9-108.2) pmol/l, P < 0.0005; normal females, 14.2 (3.9-53.5) pmol/l and HF females, 21.8 (3.9-112.5) pmol/l, P < 0.001; values are medians (range)]. The relative increase was greater in males than females ( P < 0.03). UCN fell with increasing age, especially in HF patients ( r(s) = -0.56, P < 0.0005) and with increasing New York Heart Association (NYHA) class ( r(s) = -0.55, P < 0.0005). The fall in UCN levels with increasing NYHA class was reinforced by a significant correlation between UCN and ejection fraction ( r(s) = 0.45, P < 0.0005) in HF patients. Although receiver operating characteristic (ROC) curves for diagnosis of all HF cases yielded an area under the curve (AUC) of 0.76, ROC AUCs for patients with early HF (NYHA class I and II) were better (0.91). ROC AUCs for logistic models incorporating N-terminal probrain natriuretic peptide (N-BNP) and UCN were better than either peptide alone. In conclusion, plasma UCN is elevated in HF, especially in its early stages. Its decline with increasing HF severity may expedite disease progression due to diminished cardioprotective/anti-inflammatory effects. UCN measurement may also complement N-BNP in the diagnosis of early HF.

Crystallography of the NiHfSi Phase in a NiAl (0.5 Hf) Single-Crystal Alloy

NASA Technical Reports Server (NTRS)

Garg, A.; Noebe, R. D.; Darolia, R.

1996-01-01

Small additions of Hf to conventionally processed NiAl single crystals result in the precipitation of a high density of cuboidal G-phase along with a newly identified silicide phase. Both of these phases form in the presence of Si which is not an intentional alloying addition but is a contaminant resulting from contact with the ceramic shell molds during directional solidification of the single-crystal ingots. The morphology, crystal structure and Orientation Relationship (OR) of the silicide phase in a NiAl (0.5 at.%Hf) single-crystal alloy have been determined using transmission electron microscopy, electron microdiffraction and energy dispersive X-ray spectroscopy. Qualitative elemental analysis and indexing of the electron microdiffraction patterns from the new phase indicate that it is an orthorhombic NiHfSi phase with unit cell parameters, a = 0.639 nm, b = 0.389 nm and c = 0.72 nm, and space group Pnma. The NiHfSi phase forms as thin rectangular plates on NiAl/111/ planes with an OR that is given by NiHfSi(100))(parallel) NiAl(111) and NiHfSi zone axes(010) (parallel) NiAl zone axes (101). Twelve variants of the NiHfSi phase were observed in the alloy and the number of variants and rectangular morphology of NiHfSi plates are consistent with symmetry requirements. Quenching experiments indicate that nucleation of the NiHfSi phase in NiAI(Hf) alloys is aided by the formation of NiAl group of zone axes (111) vacancy loops that form on the NiAl /111/ planes.

Risk of Incident Heart Failure in Patients With Diabetes and Asymptomatic Left Ventricular Systolic Dysfunction.

PubMed

Rørth, Rasmus; Jhund, Pardeep S; Mogensen, Ulrik M; Kristensen, Søren L; Petrie, Mark C; Køber, Lars; McMurray, John J V

2018-06-01

Although diabetes is well known to be common in prevalent heart failure (HF) and portends a poor prognosis, the role of diabetes in the development of incident HF is less well understood. We studied the role of diabetes in the transition from asymptomatic left ventricular systolic dysfunction (ALVSD) to overt HF in the prevention arm of the Studies of Left Ventricular Dysfunction (SOLVD-P). We examined the development of symptomatic HF, HF hospitalization, and cardiovascular death according to diabetes status at baseline in patients in SOLVD-P. These outcomes were analyzed by using cumulative incidence curves and Cox regression models adjusted for age, sex, and other prognostic factors, including randomized treatment, HF severity, and comorbidity. Of the 4,223 eligible participants, 647 (15%) had diabetes at baseline. Patients with diabetes were older and had a higher average weight, systolic blood pressure, and heart rate. During the median follow-up of 36 months, 861 of the 3,576 patients without diabetes (24%) developed HF compared with 214 of the 647 patients with diabetes (33%). In unadjusted analyses, patients with diabetes had a higher risk of development of HF (hazard ratio 1.53 [95% CI 1.32-1.78]; P < 0.001), HF hospitalization (2.04 [1.65-2.52]; P < 0.0001), and the composite outcome of development of HF or cardiovascular death (1.48 [1.30-1.69]; P < 0.001). The effect of enalapril on outcomes was not modified by diabetes status. In patients with ALVSD, diabetes is associated with an increased risk of developing HF. Development of HF is associated with an increased risk of death irrespective of diabetes status. © 2018 by the American Diabetes Association.

Early activation of deleterious molecular pathways in the kidney in experimental heart failure with atrial remodeling.

PubMed

Ichiki, Tomoko; Huntley, Brenda K; Harty, Gail J; Sangaralingham, S Jeson; Burnett, John C

2017-05-01

Heart failure (HF) is a major health problem with worsening outcomes when renal impairment is present. Therapeutics for early phase HF may be effective for cardiorenal protection, however the detailed characteristics of the kidney in early-stage HF (ES-HF), and therefore treatment for potential renal protection, are poorly defined. We sought to determine the gene and protein expression profiles of specific maladaptive pathways of ES-HF in the kidney and heart. Experimental canine ES-HF, characterized by de-novo HF with atrial remodeling but not ventricular fibrosis, was induced by right ventricular pacing for 10 days. Kidney cortex (KC), medulla (KM), left ventricle (LV), and left atrial (LA) tissues from ES-HF versus normal canines ( n  = 4 of each) were analyzed using RT-PCR microarrays and protein assays to assess genes and proteins related to inflammation, renal injury, apoptosis, and fibrosis. ES-HF was characterized by increased circulating natriuretic peptides and components of the renin-angiotensin-aldosterone system and decreased sodium and water excretion with mild renal injury and up-regulation of CNP and renin genes in the kidney. Compared to normals, widespread genes, especially genes of the inflammatory pathways, were up-regulated in KC similar to increases seen in LA Protein expressions related to inflammatory cytokines were also augmented in the KC Gene and protein changes were less prominent in the LV and KM The ES-HF displayed mild renal injury with widespread gene changes and increased inflammatory cytokines. These changes may provide important clues into the pathophysiology of ES-HF and for therapeutic molecular targets in the kidney of ES-HF. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Low-carbohydrate, high-fat diets have sex-specific effects on bone health in rats.

PubMed

Zengin, Ayse; Kropp, Benedikt; Chevalier, Yan; Junnila, Riia; Sustarsic, Elahu; Herbach, Nadja; Fanelli, Flaminia; Mezzullo, Marco; Milz, Stefan; Bidlingmaier, Martin; Bielohuby, Maximilian

2016-10-01

Studies in humans suggest that consumption of low-carbohydrate, high-fat diets (LC-HF) could be detrimental for growth and bone health. In young male rats, LC-HF diets negatively affect bone health by impairing the growth hormone/insulin-like growth factor axis (GH/IGF axis), while the effects in female rats remain unknown. Therefore, we investigated whether sex-specific effects of LC-HF diets on bone health exist. Twelve-week-old male and female Wistar rats were isoenergetically pair-fed either a control diet (CD), "Atkins-style" protein-matched diet (LC-HF-1), or ketogenic low-protein diet (LC-HF-2) for 4 weeks. In females, microcomputed tomography and histomorphometry analyses were performed on the distal femur. Sex hormones were analysed with liquid chromatography-tandem mass spectrometry, and endocrine parameters including GH and IGF-I were measured by immunoassay. Trabecular bone volume, serum IGF-I and the bone formation marker P1NP were lower in male rats fed both LC-HF diets versus CD. LC-HF diets did not impair bone health in female rats, with no change in trabecular or cortical bone volume nor in serum markers of bone turnover between CD versus both LC-HF diet groups. Pituitary GH secretion was lower in female rats fed LC-HF diet, with no difference in circulating IGF-I. Circulating sex hormone concentrations remained unchanged in male and female rats fed LC-HF diets. A 4-week consumption of LC-HF diets has sex-specific effects on bone health-with no effects in adult female rats yet negative effects in adult male rats. This response seems to be driven by a sex-specific effect of LC-HF diets on the GH/IGF system.

Parallel evolution of circulating FABP4 and NT-proBNP in heart failure patients

PubMed Central

2013-01-01

Background Circulating adipocyte fatty acid-binding protein (FABP4) levels are considered to be a link between obesity, insulin resistance, diabetes, and cardiovascular (CV) diseases. In vitro, FABP4 has exhibited cardiodepressant activity by suppressing cardiomyocyte contraction. We have explored the relationship between FABP4 and the N-terminal fragment of pro-B-type natriuretic peptide (NT-proBNP) as a clinical parameter of heart failure (HF). Methods We included 179 stable HF patients who were referred to a specialized HF unit, 108 of whom were prospectively followed for up to 6 months. A group of 163 non-HF patients attending a CV risk unit was used as the non-HF control group for the FABP4 comparisons. Results In the HF patients, FABP4 and NT-proBNP were assayed, along with a clinical and functional assessment of the heart at baseline and after 6 months of specialized monitoring. The FABP4 levels were higher in the patients with HF than in the non-HF high CV risk control group (p<0.001). The FABP4 levels were associated with the NT-proBNP levels in patients with HF (r=0.601, p<0.001), and this association was stronger in the diabetic patients. FABP4 was also associated with heart rate and the results of the 6-minute walk test. After the follow-up period, FABP4 decreased in parallel to NT-proBNP and to the clinical parameters of HF. Conclusions FABP4 is associated with the clinical manifestations and biomarkers of HF. It exhibits a parallel evolution with the circulating levels of NT-proBNP in HF patients. PMID:23642261

Parallel evolution of circulating FABP4 and NT-proBNP in heart failure patients.

PubMed

Cabré, Anna; Valdovinos, Pilar; Lázaro, Iolanda; Bonet, Gil; Bardají, Alfredo; Masana, Lluís

2013-05-04

Circulating adipocyte fatty acid-binding protein (FABP4) levels are considered to be a link between obesity, insulin resistance, diabetes, and cardiovascular (CV) diseases. In vitro, FABP4 has exhibited cardiodepressant activity by suppressing cardiomyocyte contraction. We have explored the relationship between FABP4 and the N-terminal fragment of pro-B-type natriuretic peptide (NT-proBNP) as a clinical parameter of heart failure (HF). We included 179 stable HF patients who were referred to a specialized HF unit, 108 of whom were prospectively followed for up to 6 months. A group of 163 non-HF patients attending a CV risk unit was used as the non-HF control group for the FABP4 comparisons. In the HF patients, FABP4 and NT-proBNP were assayed, along with a clinical and functional assessment of the heart at baseline and after 6 months of specialized monitoring. The FABP4 levels were higher in the patients with HF than in the non-HF high CV risk control group (p<0.001). The FABP4 levels were associated with the NT-proBNP levels in patients with HF (r=0.601, p<0.001), and this association was stronger in the diabetic patients. FABP4 was also associated with heart rate and the results of the 6-minute walk test. After the follow-up period, FABP4 decreased in parallel to NT-proBNP and to the clinical parameters of HF. FABP4 is associated with the clinical manifestations and biomarkers of HF. It exhibits a parallel evolution with the circulating levels of NT-proBNP in HF patients.

Soluble Fermentable Dietary Fibre (Pectin) Decreases Caloric Intake, Adiposity and Lipidaemia in High-Fat Diet-Induced Obese Rats

PubMed Central

Adam, Clare L.; Thomson, Lynn M.; Williams, Patricia A.; Ross, Alexander W.

2015-01-01

Consumption of a high fat diet promotes obesity and poor metabolic health, both of which may be improved by decreasing caloric intake. Satiety-inducing ingredients such as dietary fibre may be beneficial and this study investigates in diet-induced obese (DIO) rats the effects of high or low fat diet with or without soluble fermentable fibre (pectin). In two independently replicated experiments, young adult male DIO rats that had been reared on high fat diet (HF; 45% energy from fat) were given HF, low fat diet (LF; 10% energy from fat), HF with 10% w/w pectin (HF+P), or LF with 10% w/w pectin (LF+P) ad libitum for 4 weeks (n = 8/group/experiment). Food intake, body weight, body composition (by magnetic resonance imaging), plasma hormones, and plasma and liver lipid concentrations were measured. Caloric intake and body weight gain were greatest in HF, lower in LF and HF+P, and lowest in the LF+P group. Body fat mass increased in HF, was maintained in LF, but decreased significantly in LF+P and HF+P groups. Final plasma leptin, insulin, total cholesterol and triglycerides were lower, and plasma satiety hormone PYY concentrations were higher, in LF+P and HF+P than in LF and HF groups, respectively. Total fat and triglyceride concentrations in liver were greatest in HF, lower in LF and HF+P, and lowest in the LF+P group. Therefore, the inclusion of soluble fibre in a high fat (or low fat) diet promoted increased satiety and decreased caloric intake, weight gain, adiposity, lipidaemia, leptinaemia and insulinaemia. These data support the potential of fermentable dietary fibre for weight loss and improving metabolic health in obesity. PMID:26447990

Supply Chain Modeling for Fluorspar and Hydroflouric Acid and Implications for Further Analyses

DTIC Science & Technology

2015-04-01

Critical Materials, Volume 1 Chapter 2. Fluorspar-HF Supply Chain 4 Foreign Supply Other usesUS Supply Fluorspar Mining HF Production Downstream...analysis are listed across the top: Fluorspar Mining , HF Production, and (pro- duction of) Downstream Products (using HF). • U.S. supply is represented by...material flows from fluorspar mining , to HF production, to downstream fluorine-containing products. – Black lines are material flows included in the supply

Systolic Blood Pressure and Incident Heart Failure in the Elderly

PubMed Central

Butler, Javed; Kalogeropoulos, Andreas P.; Georgiopoulou, Vasiliki V.; Bibbins-Domingo, Kirsten; Najjar, Samer S.; Sutton-Tyrrell, Kim C.; Harris, Tamara B.; Kritchevsky, Stephen B.; Lloyd-Jones, Donald M.; Newman, Anne B.; Psaty, Bruce M.

2013-01-01

Objectives The exact form of the association between systolic blood pressure (SBP) and heart failure (HF) risk in the elderly remains incompletely defined, especially in individuals not receiving antihypertensive medications. Our aim was to examine the association between SBP and HF risk in the elderly. Design Competing-risks proportional hazards modeling of incident HF risk, utilizing 10-year follow-up data from two NIH-sponsored cohort studies; the Cardiovascular Health Study (inception: 1989-90 and 1992-93) and the Health ABC Study (inception: 1997-98). Setting Community-based cohorts. Participants 4408 participants (age, 72.8 [4.9] years; 53.1% women, 81.7% white; 18.3% black) without prevalent HF and not receiving antihypertensive medications at baseline. Main outcome measures Incident HF, defined as first adjudicated hospitalisation for HF. Results Over 10 years, 493 (11.1%) participants developed HF. Prehypertension (120-139 mmHg), stage 1 (140-159 mmHg), and stage 2 (≥160 mmHg) hypertension were associated with escalating HF risk; hazard ratios vs. optimal SBP (<120 mmHg) in competing-risks models controlling for clinical characteristics were 1.63 (95% CI, 1.23-2.16; P=0.001), 2.21 (95% CI, 1.65-2.96; P<0.001), and 2.60 (95% CI, 1.85-364; P<0.001), respectively. Overall 255 of 493 (51.7%) HF events occurred in participants with SBP <140 mm Hg at baseline. Increasing SBP was associated with higher HF risk in women than men; no race-SBP interaction was observed. In analyses with continuous SBP, HF risk had a continuous positive association with SBP to levels as low as 113 mmHg in men and 112 mmHg in women. Conclusions There is a continuous positive association between SBP and HF risk in the elderly for levels of SBP as low as <115 mmHg; over half of incident HF events occur in individuals with SBP <140 mmHg. PMID:21636845

Heart Failure Is Common and Under-Recognized in Patients With Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia.

PubMed

Gilotra, Nisha A; Bhonsale, Aditya; James, Cynthia A; Te Riele, Anneline S J; Murray, Brittney; Tichnell, Crystal; Sawant, Abhishek; Ong, Chin Siang; Judge, Daniel P; Russell, Stuart D; Calkins, Hugh; Tedford, Ryan J

2017-09-01

Heart failure (HF) prevalence in arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) varies depending on study cohort and is not well characterized. This study sought to determine prevalence and predictors of HF in ARVC/D. Clinical HF, defined as at least 1 HF sign or symptom, was retrospectively adjudicated for 289 patients meeting ARVC/D Task Force Criteria. HF was present in 142 patients (49%): 113 had isolated RV involvement and 29 had evidence of LV dysfunction. Average age of HF onset was 40±14 years. Most commonly reported symptoms were exertional dyspnea (78%) and fatigue (73%). Only 40% (n=57/142) had signs of volume overload. Left-sided HF signs were rare. Patients with clinical HF before ARVC/D diagnosis (n=31) were older ( P =0.005) and met fewer Task Force Criteria ( P =0.013) than those who developed HF after ARVC/D presentation. Female sex (odds ratio, 2.2; 95% confidence interval, 1.21-4.01; P =0.01) and lateral precordial T-wave inversions (odds ratio, 9.87; 95% confidence interval, 1.07-91.1; P =0.043) were associated with increased odds of HF. Additionally, patients with symptomatic LV dysfunction had higher odds of lateral precordial T-wave inversions (odds ratio, 18.4; 95% confidence interval, 2.92-116.18; P =0.002). Patients with HF were more likely to undergo heart transplantation (15/142 versus 1/147; P <0.001) or die during study follow-up period (7 versus 0; P =0.007). HF symptoms, especially exertional dyspnea, are common in ARVC/D; yet, classic left-sided signs are typically absent and less than half have evidence of volume overload. Given the unique predominately right-sided phenotype, a large portion of patients with HF may be under-recognized. © 2017 American Heart Association, Inc.

Long-term follow-up in optimally treated and stable heart failure patients: primary care vs. heart failure clinic. Results of the COACH-2 study.

PubMed

Luttik, Marie Louise A; Jaarsma, Tiny; van Geel, Peter Paul; Brons, Maaike; Hillege, Hans L; Hoes, Arno W; de Jong, Richard; Linssen, Gerard; Lok, Dirk J A; Berge, Marjolein; van Veldhuisen, Dirk J

2014-11-01

It has been suggested that home-based heart failure (HF) management in primary care may be an alternative to clinic-based management in HF patients. However, little is known about adherence to HF guidelines and adherence to the medication regimen in these home-based programmes. The aim of the current study was to determine whether long-term follow-up and treatment in primary care is equally effective as follow-up at a specialized HF clinic in terms of guideline adherence and patient adherence, in HF patients initially managed and up-titrated to optimal treatment at a specialized HF clinic. We conducted a multicentre, randomized, controlled study in 189 HF patients (62% male, age 72 ± 11 years), who were assigned to follow-up either in primary care (n = 97) or in a HF clinic (n = 92). After 12 months, no differences between guideline adherence, as estimated by the Guideline Adherence Indicator (GAI-3), and patient adherence, in terms of the medication possession ratio (MPR), were found between treatment groups. There was no difference in the number of deaths (n = 12 in primary care and n = 8 in the HF clinic; P = 0.48), and hospital readmissions for cardiovascular (CV) reasons were also similar. The total number of unplanned non-CV hospital readmissions, however, tended to be higher in the primary care group (n = 22) than in the HF clinic group (n = 10; P = 0.05). Patients discharged after initial management in a specialized HF clinic can be discharged to primary care for long-term follow-up with regard to maintaining guideline adherence and patient adherence. However, the complexity of the HF syndrome and its associated co-morbidities requires continuous monitoring. Close collaboration between healthcare providers will be crucial in order to provide HF patients with optimal, integrated care. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

Mitochondrial ROS Drive Sudden Cardiac Death and Chronic Proteome Remodeling in Heart Failure.

PubMed

Dey, Swati; DeMazumder, Deeptankar; Sidor, Agnieszka; Foster, D B; O'Rourke, Brian

2018-06-13

Rationale: Despite increasing prevalence and incidence of heart failure (HF), therapeutic options remain limited. In early stages of HF, sudden cardiac death (SCD) from ventricular arrhythmias claims many lives. Reactive oxygen species (ROS) have been implicated in both arrhythmias and contractile dysfunction. However, little is known about how ROS in specific subcellular compartments contribute to HF or SCD pathophysiology. The role of ROS in chronic proteome remodeling has not been explored. Objective: We will test the hypothesis that elevated mitochondrial ROS (mROS) is a principal source of oxidative stress in HF and in vivo reduction of mROS mitigates SCD. Methods and Results: Using a unique guinea pig model of non-ischemic HF that recapitulates important features of human HF, including prolonged QT interval and high incidence of spontaneous arrhythmic SCD. Compartment-specific ROS sensors revealed increased mROS in resting and contracting left ventricular (LV) myocytes in failing hearts. Importantly, mitochondrially-targeted antioxidant (MitoTEMPO) normalized global cellular ROS. Further, in vivo MitoTEMPO treatment of HF animals prevented and reversed HF; eliminated SCD by decreasing dispersion of repolarization and ventricular arrhythmias; suppressed chronic HF-induced remodeling of the expression proteome; and prevented specific phosphoproteome alterations. Pathway analysis of mROS-sensitive networks indicated that increased mROS in HF disrupts the normal coupling between cytosolic signals and nuclear gene programs driving mitochondrial function, antioxidant enzymes, Ca2+ handling and action potential repolarization, suggesting new targets for therapeutic intervention. Conclusions: mROS drive both acute emergent events, such as electrical instability responsibly for SCD, and those that mediate chronic HF remodeling, characterized by suppression or altered phosphorylation of metabolic, antioxidant and ion transport protein networks. In vivo reduction of mROS prevents and reverses electrical instability, SCD and HF. Our findings support the feasibility of targeting the mitochondria as a potential new therapy for HF and SCD while identifying new mROS-sensitive protein modifications.

Prognostic Significance of Interleukin-34 (IL-34) in Patients With Chronic Heart Failure With or Without Renal Insufficiency.

PubMed

Tao, Rong; Fan, Qin; Zhang, Hang; Xie, Hongyang; Lu, Lin; Gu, Gang; Wang, Fang; Xi, Rui; Hu, Jian; Chen, Qiujing; Niu, Wenquan; Shen, Weifeng; Zhang, Ruiyan; Yan, Xiaoxiang

2017-04-01

Renal dysfunction, commonly associated with cardiac dysfunction, has predictive value for adverse long-term outcomes in heart failure (HF). We previously identified a novel renal biomarker, interleukin-34 (IL-34), elevated in HF patients and associated with kidney dysfunction and coronary artery disease during HF. However, the prognostic value of IL-34 in HF remains unclear, so that the present study aimed to determine it. This prospective, observational study included 510 consecutive HF patients with their serum IL-34 as well as other variables measured at baseline, and they were followed up for 2 years. The primary end point was a composite of cardiovascular death or a first HF hospitalization, with cardiovascular death, HF hospitalization, and all-cause mortality as secondary outcomes. There was a significant and gradual increase in risk as IL-34 increased, determined by log-rank tests with Kaplan-Meier curves. Serum IL-34 was also a significant prognostic predictor of the primary end point (1.301 [1.115-1.518]; P =0.001), cardiovascular death (1.347 [1.096-1.655]; P =0.005), HF hospitalization (1.234 [1.018-1.494]; P =0.032), and all-cause mortality (1.343 [1.115-1.618]; P =0.002) in HF as per SD increase in the log IL-34 level after adjusting for age, sex, traditional risk factors, and N-terminal pro-brain natriuretic peptide. Especially, IL-34 had a more-significant prognostic value in HF patients with kidney impairment than those without. IL-34 is a significant predictor of cardiovascular death, HF hospitalization, and all-cause mortality in chronic HF, especially when concomitant with renal dysfunction. Serum IL-34 measurement may provide new insights linking kidney impairment to poor HF outcomes beyond other renal markers. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Kansas City Cardiomyopathy Questionnaire Score Is Associated With Incident Heart Failure Hospitalization in Patients With Chronic Kidney Disease Without Previously Diagnosed Heart Failure: Chronic Renal Insufficiency Cohort Study.

PubMed

Mishra, Rakesh K; Yang, Wei; Roy, Jason; Anderson, Amanda H; Bansal, Nisha; Chen, Jing; DeFilippi, Christopher; Delafontaine, Patrice; Feldman, Harold I; Kallem, Radhakrishna; Kusek, John W; Lora, Claudia M; Rosas, Sylvia E; Go, Alan S; Shlipak, Michael G

2015-07-01

Chronic kidney disease is a risk factor for heart failure (HF). Patients with chronic kidney disease without diagnosed HF have an increased burden of symptoms characteristic of HF. It is not known whether these symptoms are associated with occurrence of new onset HF. We studied the association of a modified Kansas City Cardiomyopathy Questionnaire with newly identified cases of hospitalized HF among 3093 participants enrolled in the Chronic Renal Insufficiency Cohort (CRIC) Study who did not report HF at baseline. The annually updated Kansas City Cardiomyopathy Questionnaire score was categorized into quartiles (Q1-4) with the lower scores representing the worse symptoms. Multivariable-adjusted repeated measure logistic regression models were adjusted for demographic characteristics, clinical risk factors for HF, N-terminal probrain natriuretic peptide level and left ventricular hypertrophy, left ventricular systolic and diastolic dysfunction. Over a mean (±SD) follow-up period of 4.3±1.6 years, there were 211 new cases of HF hospitalizations. The risk of HF hospitalization increased with increasing symptom quartiles; 2.62, 1.85, 1.14, and 0.74 events per 100 person-years, respectively. The median number of annual Kansas City Cardiomyopathy Questionnaire assessments per participant was 5 (interquartile range, 3-6). The annually updated Kansas City Cardiomyopathy Questionnaire score was independently associated with higher risk of incident HF hospitalization in multivariable-adjusted models (odds ratio, 3.30 [1.66-6.52]; P=0.001 for Q1 compared with Q4). Symptoms characteristic of HF are common in patients with chronic kidney disease and are associated with higher short-term risk for new hospitalization for HF, independent of level of kidney function, and other known HF risk factors. © 2015 American Heart Association, Inc.

The obesity paradox in men with coronary heart disease and heart failure: the role of muscle mass and leptin.

PubMed

Wannamethee, S Goya; Shaper, A Gerald; Whincup, Peter H; Lennon, Lucy; Papacosta, Olia; Sattar, Naveed

2014-01-15

We have investigated the role of muscle mass, natriuretic peptides and adipokines in explaining the obesity paradox. The obesity paradox relates to the association between obesity and increased survival in patients with coronary heart disease (CHD) or heart failure (HF). Prospective study of 4046 men aged 60-79 years followed up for a mean period of 11 years, during which 1340 deaths occurred. The men were divided according to the presence of doctor diagnosed CHD and HF: (i) no CHD or HF ii), with CHD (no HF) and (iii) with HF. Overweight (BMI 25-9.9 kg/m(2)) and obesity (BMI ≥ 30 kg/m(2)) were associated with lower mortality risk compared to men with normal weight (BMI 18.5-24.9 kg/m(2)) in those with CHD [hazards ratio (HR) 0.71 (0.56,0.91) and 0.77 (0.57,1.04); p=0.04 for trend] and in those with HF [HR 0.57 (0.28,1.16) and 0.41 (0.16,1.09; p=0.04 for trend). Adjustment for muscle mass and NT-proBNP attenuated the inverse association in those with CHD (no HF) [HR 0.78 (0.61,1.01) and 0.96 (0.68,1.36) p=0.60 for trend) but made minor differences to those with HF [p=0.05]. Leptin related positively to mortality in men without HF but inversely to mortality in those with HF; adjustment for leptin abolished the BMI mortality association in men with HF [HR 0.82 (0.31,2.20) and 0.99 (0.27,3.71); p=0.98 for trend]. The lower mortality risk associated with excess weight in men with CHD without HF may be due to higher muscle mass. In men with HF, leptin (possibly reflecting cachexia) explain the inverse association. Copyright © 2013. Published by Elsevier Ireland Ltd.

Type 2 diabetes mellitus and heart failure: a position statement from the Heart Failure Association of the European Society of Cardiology.

PubMed

Seferović, Petar M; Petrie, Mark C; Filippatos, Gerasimos S; Anker, Stefan D; Rosano, Giuseppe; Bauersachs, Johann; Paulus, Walter J; Komajda, Michel; Cosentino, Francesco; de Boer, Rudolf A; Farmakis, Dimitrios; Doehner, Wolfram; Lambrinou, Ekaterini; Lopatin, Yuri; Piepoli, Massimo F; Theodorakis, Michael J; Wiggers, Henrik; Lekakis, John; Mebazaa, Alexandre; Mamas, Mamas A; Tschöpe, Carsten; Hoes, Arno W; Seferović, Jelena P; Logue, Jennifer; McDonagh, Theresa; Riley, Jillian P; Milinković, Ivan; Polovina, Marija; van Veldhuisen, Dirk J; Lainscak, Mitja; Maggioni, Aldo P; Ruschitzka, Frank; McMurray, John J V

2018-05-01

The coexistence of type 2 diabetes mellitus (T2DM) and heart failure (HF), either with reduced (HFrEF) or preserved ejection fraction (HFpEF), is frequent (30-40% of patients) and associated with a higher risk of HF hospitalization, all-cause and cardiovascular (CV) mortality. The most important causes of HF in T2DM are coronary artery disease, arterial hypertension and a direct detrimental effect of T2DM on the myocardium. T2DM is often unrecognized in HF patients, and vice versa, which emphasizes the importance of an active search for both disorders in the clinical practice. There are no specific limitations to HF treatment in T2DM. Subanalyses of trials addressing HF treatment in the general population have shown that all HF therapies are similarly effective regardless of T2DM. Concerning T2DM treatment in HF patients, most guidelines currently recommend metformin as the first-line choice. Sulphonylureas and insulin have been the traditional second- and third-line therapies although their safety in HF is equivocal. Neither glucagon-like preptide-1 (GLP-1) receptor agonists, nor dipeptidyl peptidase-4 (DPP4) inhibitors reduce the risk for HF hospitalization. Indeed, a DPP4 inhibitor, saxagliptin, has been associated with a higher risk of HF hospitalization. Thiazolidinediones (pioglitazone and rosiglitazone) are contraindicated in patients with (or at risk of) HF. In recent trials, sodium-glucose co-transporter-2 (SGLT2) inhibitors, empagliflozin and canagliflozin, have both shown a significant reduction in HF hospitalization in patients with established CV disease or at risk of CV disease. Several ongoing trials should provide an insight into the effectiveness of SGLT2 inhibitors in patients with HFrEF and HFpEF in the absence of T2DM. © 2018 The Authors. European Journal of Heart Failure © 2018 European Society of Cardiology.

Effects of nitrogen incorporation in HfO(2) grown on InP by atomic layer deposition: an evolution in structural, chemical, and electrical characteristics.

PubMed

Kang, Yu-Seon; Kim, Dae-Kyoung; Kang, Hang-Kyu; Jeong, Kwang-Sik; Cho, Mann-Ho; Ko, Dae-Hong; Kim, Hyoungsub; Seo, Jung-Hye; Kim, Dong-Chan

2014-03-26

We investigated the effects of postnitridation on the structural characteristics and interfacial reactions of HfO2 thin films grown on InP by atomic layer deposition (ALD) as a function of film thickness. By postdeposition annealing under NH3 vapor (PDN) at 600 °C, an InN layer formed at the HfO2/InP interface, and ionized NHx was incorporated in the HfO2 film. We demonstrate that structural changes resulting from nitridation of HfO2/InP depend on the film thickness (i.e., a single-crystal interfacial layer of h-InN formed at thin (2 nm) HfO2/InP interfaces, whereas an amorphous InN layer formed at thick (>6 nm) HfO2/InP interfaces). Consequently, the tetragonal structure of HfO2 transformed into a mixture structure of tetragonal and monoclinic because the interfacial InN layer relieved interfacial strain between HfO2 and InP. During postdeposition annealing (PDA) in HfO2/InP at 600 °C, large numbers of oxidation states were generated as a result of interfacial reactions between interdiffused oxygen impurities and out-diffused InP substrate elements. However, in the case of the PDN of HfO2/InP structures at 600 °C, nitrogen incorporation in the HfO2 film effectively blocked the out-diffusion of atomic In and P, thus suppressing the formation of oxidation states. Accordingly, the number of interfacial defect states (Dit) within the band gap of InP was significantly reduced, which was also supported by DFT calculations. Interfacial InN in HfO2/InP increased the electron-barrier height to ∼0.6 eV, which led to low-leakage-current density in the gate voltage region over 2 V.

Association of electrocardiogram abnormalities and incident heart failure events.

PubMed

Gencer, Baris; Butler, Javed; Bauer, Douglas C; Auer, Reto; Kalogeropoulos, Andreas; Marques-Vidal, Pedro; Applegate, William B; Satterfield, Suzanne; Harris, Tamara; Newman, Anne; Vittinghoff, Eric; Rodondi, Nicolas

2014-06-01

Unless effective preventive strategies are implemented, aging of the population will result in a significant worsening of the heart failure (HF) epidemic. Few data exist on whether baseline electrocardiographic (ECG) abnormalities can refine risk prediction for HF. We examined a prospective cohort of 2,915 participants aged 70 to 79 years without preexisting HF, enrolled between April 1997 and June 1998 in the Health, Aging, and Body Composition (Health ABC) study. Minnesota Code was used to define major and minor ECG abnormalities at baseline and at year 4 follow-up. Using Cox models, we assessed (1) the association between ECG abnormalities and incident HF and (2) the incremental value of adding ECG to the Health ABC HF Risk Score using the net reclassification index. At baseline, 380 participants (13.0%) had minor, and 620 (21.3%) had major ECG abnormalities. During a median follow-up of 11.4 years, 485 participants (16.6%) developed incident HF. After adjusting for the Health ABC HF Risk Score variables, the hazard ratio (HR) was 1.27 (95% CI 0.96-1.68) for minor and 1.99 (95% CI 1.61-2.44) for major ECG abnormalities. At year 4, 263 participants developed new and 549 had persistent abnormalities; both were associated with increased subsequent HF risk (HR 1.94, 95% CI 1.38-2.72 for new and HR 2.35, 95% CI 1.82-3.02 for persistent ECG abnormalities). Baseline ECG correctly reclassified 10.5% of patients with HF events, 0.8% of those without HF events, and 1.4% of the overall population. The net reclassification index across the Health ABC HF risk categories was 0.11 (95% CI 0.03-0.19). Among older adults, baseline and new ECG abnormalities are independently associated with increased risk of HF. The contribution of ECG screening for targeted prevention of HF should be evaluated in clinical trials. Copyright © 2014 Mosby, Inc. All rights reserved.

QAPP for Analysis of Data Received from Nine Hydraulic Fracturing (HF) Service Companies

EPA Pesticide Factsheets

This QAPP provides information concerning the Water Acquisition, Chemical Mixing, Well Injection, and Flowback and Produced Water stages of the HF water cycle as found in Figure 1 of the HF QMP and as described in HF Study Plan.

Study on Brewster angle thin film polarizer using hafnia-silica mixture as high-refractive-index material

NASA Astrophysics Data System (ADS)

Xu, Nuo; Zhu, Meiping; Sun, Jian; Chai, Yingjie; Kui, Yi; Zhao, Yuanan; Shao, Jianda

2018-02-01

Two kinds of polarizer coatings were prepared by electron beam evaporation, using HfO2-SiO2 mixture and HfO2 as the high-refractive-index materials, respectively. The HfO2-SiO2 mixture layer was implemented by coevaporating SiO2 and metal Hf, the materials were deposited at an oxygen atmosphere to achieve stoichiometric coatings. The certain HfO2 and SiO2 content ratio is controlled by adjusting the deposition rate of HfO2 and SiO2 using individual quartz crystal monitor. The spectral performance, surface and interfacial properties, as well as the laser-induced damage performance were studied and compared. Comparing with polarizer coating using HfO2 as high-refractive-index material, the polarizer coating using HfO2-SiO2 mixture as high-refractive-index material shows better performance with broader polarizing bandwidth, lower surface roughness, better interfacial property while maintaining high laser-induced damage threshold.

Impact of the implementation of telemanagement on a disease management program in an elderly heart failure cohort.

PubMed

Gambetta, Miguel; Dunn, Patrick; Nelson, Dawn; Herron, Bobbi; Arena, Ross

2007-01-01

The purpose of the present investigation is to examine the impact of a telemanagement component on an outpatient disease management program in patients with heart failure (HF). A total of 282 patients in whom HF was diagnosed and who were enrolled in an outpatient HF program were included in this analysis. One hundred fifty-eight patients additionally participated in a self-directed telemanagement component. The remaining 124 patients received care at an HF clinic but declined telemanagement. During the 7-month tracking period, 19 patients in the HF clinic plus telemanagement group and 53 patients in the HF clinic only group were hospitalized for cardiac reasons (log rank, 36.0; P<.001). The HF clinic only group had a significantly higher risk for hospitalization (hazard ratio, 4.0; 95% confidence interval, 2.4-6.7; P<.001). The results of the present study indicate that telemanagement is an important component of a disease management program in patients with HF.

Influence of atrial fibrillation on plasma von willebrand factor, soluble E-selectin, and N-terminal pro B-type natriuretic peptide levels in systolic heart failure.

PubMed

Freestone, Bethan; Gustafsson, Finn; Chong, Aun Yeong; Corell, Pernille; Kistorp, Caroline; Hildebrandt, Per; Lip, Gregory Y H

2008-05-01

Endothelial dysfunction is present in patients with heart failure (HF) due to left ventricular systolic dysfunction, as well as in patients with atrial fibrillation (AF) who have normal cardiac function. It is unknown whether AF influences the degree of endothelial dysfunction in patients with systolic HF. We measured levels of plasma von Willebrand factor (vWF) and E-selectin (as indexes of endothelial damage/dysfunction and endothelial activation, respectively; both enzyme-linked immunosorbent assay) in patients with AF and HF (AF-HF), who were compared to patients with sinus rhythm and HF (SR-HF), as well as in age-matched, healthy, control subjects. We also assessed the relationship of vWF and E-selectin to plasma N-terminal pro B-type natriuretic peptide (NTpro-BNP), a marker for HF severity and prognosis. One hundred ninety patients (73% men; mean age, 69.0 +/- 10.1 years [+/- SD]) with systolic HF were studied, who were compared to 117 healthy control subjects: 52 subjects (27%) were in AF, while 138 subjects (73%) were in sinus rhythm. AF-HF patients were older than SR-HF patients (p = 0.046), but left ventricular ejection fraction and New York Heart Association class were similar. There were significant differences in NT-proBNP (p < 0.0001) and plasma vWF (p = 0.003) between patients and control subjects. On Tukey post hoc analysis, AF-HF patients had significantly increased NT-proBNP (p < 0.001) and vWF (p = 0.0183) but not E-selectin (p = 0.071) levels when compared to SR-HF patients. On multivariate analysis, the presence of AF was related to plasma vWF levels (p = 0.018). Plasma vWF was also significantly correlated with NT-proBNP levels (Spearman r = 0.139; p = 0.017). There is evidence of greater endothelial damage/dysfunction in AF-HF patients when compared to SR-HF patients. The clinical significance of this is unclear but may have prognostic value.

Lipophilic versus hydrophilic statin therapy for heart failure: a protocol for an adjusted indirect comparison meta-analysis

PubMed Central

2013-01-01

Background Statins are known to reduce cardiovascular morbidity and mortality in primary and secondary prevention studies. Subsequently, a number of nonrandomised studies have shown statins improve clinical outcomes in patients with heart failure (HF). Small randomised controlled trials (RCT) also show improved cardiac function, reduced inflammation and mortality with statins in HF. However, the findings of two large RCTs do not support the evidence provided by previous studies and suggest statins lack beneficial effects in HF. Two meta-analyses have shown statins do not improve survival, whereas two others showed improved cardiac function and reduced inflammation in HF. It appears lipophilic statins produce better survival and other outcome benefits compared to hydrophilic statins. But the two types have not been compared in direct comparison trials in HF. Methods/design We will conduct a systematic review and meta-analysis of lipophilic and hydrophilic statin therapy in patients with HF. Our objectives are: 1. To determine the effects of lipophilic statins on (1) mortality, (2) hospitalisation for worsening HF, (3) cardiac function and (4) inflammation. 2. To determine the effects of hydrophilic statins on (1) mortality, (2) hospitalisation for worsening HF, (3) cardiac function and (4) inflammation. 3. To compare the efficacy of lipophilic and hydrophilic statins on HF outcomes with an adjusted indirect comparison meta-analysis. We will conduct an electronic search of databases for RCTs that evaluate statins in patients with HF. The reference lists of all identified studies will be reviewed. Two independent reviewers will conduct the search. The inclusion criteria include: 1. RCTs comparing statins with placebo or no statin in patients with symptomatic HF. 2. RCTs that employed the intention-to-treat (ITT) principle in data analysis. 3. Symptomatic HF patients of all aetiologies and on standard treatment. 4. Statin of any dose as intervention. 5. Placebo or no statin arm as control. The exclusion criteria include: 1. RCTs involving cerivastatin in HF patients. 2. RCTs with less than 4 weeks of follow-up. Discussion We will perform an adjusted indirect comparison meta-analysis of lipophilic versus hydrophilic statins in patients with HF using placebo or no statin arm as common comparator. PMID:23618535

Study of {sup 179}Hf{sup m2} excitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vishnevsky, I. N.; Zheltonozhsky, V. A., E-mail: zhelton@kinr.kiev.ua; Savrasov, A. N.

Isomeric ratios of {sup 179}Hf{sup m2,g} yields in the (γ, n) reaction and the cross section for the {sup 179}Hf{sup m2} population in the (α, p) reaction are measured for the first time at the end-point energies of 15.1 and 17.5 MeV for bremsstrahlung photons and 26 MeV for alpha particles. The results are σ = (1.1 ± 0.11) × 10{sup −27} cm{sup 2} for the {sup 176}Lu(α, p){sup 179}Hf{sup m2} reaction and Y{sub m2}/Y{sub g} = (6.1 ± 0.3) × 10{sup −6} and (3.7 ± 0.2) × 10{sup −6} for the {sup 180}Hf(γ, n){sup 179}Hf{sup m22} reaction at E{submore » ep} =15.1 and 17.5 MeV, respectively. The experimental data on the relative {sup 179}Hf{sup m2} yield indicate a single-humped shape of the excitation function for the {sup 180}Hf(γ, n){sup 179}Hf{sup m2} reaction. Simulation is performed using the TALYS-1.4 and EMPIRE-3.2 codes.« less

Shelf-life extension of preservative-free hydrated feed using gamma pasteurization and its effect on growth performance of eel

NASA Astrophysics Data System (ADS)

Kim, Dongho; Song, Hyunpa; Lim, Sangyong; Jo, Minho; Song, Duseop; Jo, Cheorun

2012-08-01

Hydrated feed (HF) promotes the growth performance and shortens the feeding time of fish by increasing the efficiency of digestion. However, the shelf-life of HF is a concern due to its relatively higher water content. In this study, radiation pasteurization was applied to improve the shelf-life and microbiological quality of HF for fish farming. Preservative-free HF containing 25% moisture was gamma-irradiated and its microbiological and nutritional properties evaluated in addition to a practical feeding trial carried out using eel. The viable counts of bacteria and fungi in HF were 106 and 104 CFU/g, respectively. All coliform bacteria and yeast in HF were eliminated by irradiation at a dose of 5 kGy, and total aerobic bacteria were eliminated at 10 kGy. The shelf-life of the preservative-free and irradiated (10 kGy) HF was estimated as 6 months under ambient conditions. The nutritional composition of HF was stable up to 10 kGy of irradiation. Based on a feeding trial, it was proven that eel fed HF had about 20% higher growth rate than that fed dried feed.

Evaluation of cermet materials suitable for lithium lubricated thrust bearings for high temperature operation

NASA Technical Reports Server (NTRS)

Sinclair, J. H.; Hendrixson, W. H.

1974-01-01

Cerment materials (HfC - 10 wt% W; HfC - 10 wt% TaC - 10 wt%W; HfC - 2 wt% CbC - 8 wt% Mo;Hfn - 10 wt% W; Hfn - 10 wt% TaN - 10 wt% W; and ZrC - 17 wt% W) were evaluated for possible use as lithium-lubricated bearings in the control system of a nuclear reactor. Tests of compatibility with lithium were made in T-111 (Ta-8W-2Hf) capsules at temperatures up to 1090 C. The tendencies of HfC-TaC-W, HfC-CbC-Mo, and HfN-W to bond to themselves and to the refractory alloys T-111 and TZM when enclosed in lithium-filled capsules under a pressure of 2000 psi at 980 and 1200 C for 1933 hours were evaluated. Thermal expansion characteristics were determined for the same three materials from room temperature to 1200 C. On the basis of these tests, HfC-10 TaC-10W and HfN-10W were selected as the best and second best candidates, respectively, of the materials tested for the bearing application.

The Unimolecular Reactions of CF3CHF2 Studied by Chemical Activation: Assignment of Rate Constants and Threshold Energies to the 1,2-H Atom Transfer, 1,1-HF and 1,2-HF Elimination Reactions, and the Dependence of Threshold Energies on the Number of F-Atom Substituents in the Fluoroethane Molecules.

PubMed

Smith, Caleb A; Gillespie, Blanton R; Heard, George L; Setser, D W; Holmes, Bert E

2017-11-22

The recombination of CF 3 and CHF 2 radicals in a room-temperature bath gas was used to prepare vibrationally excited CF 3 CHF 2 * molecules with 101 kcal mol -1 of vibrational energy. The subsequent 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions were observed as a function of bath gas pressure by following the CHF 3 , CF 3 (F)C: and C 2 F 4 product concentrations by gas chromatography using a mass spectrometer as the detector. The singlet CF 3 (F)C: concentration was measured by trapping the carbene with trans-2-butene. The experimental rate constants are 3.6 × 10 4 , 4.7 × 10 4 , and 1.1 × 10 4 s -1 for the 1,2-H atom transfer and 1,1-HF and 1,2-HF elimination reactions, respectively. These experimental rate constants were matched to statistical RRKM calculated rate constants to assign threshold energies (E 0 ) of 88 ± 2, 88 ± 2, and 87 ± 2 kcal mol -1 to the three reactions. Pentafluoroethane is the only fluoroethane that has a competitive H atom transfer decomposition reaction, and it is the only example with 1,1-HF elimination being more important than 1,2-HF elimination. The trend of increasing threshold energies for both 1,1-HF and 1,2-HF processes with the number of F atoms in the fluoroethane molecule is summarized and investigated with electronic-structure calculations. Examination of the intrinsic reaction coordinate associated with the 1,1-HF elimination reaction found an adduct between CF 3 (F)C: and HF in the exit channel with a dissociation energy of ∼5 kcal mol -1 . Hydrogen-bonded complexes between HF and the H atom migration transition state of CH 3 (F)C: and the F atom migration transition state of CF 3 (F)C: also were found by the calculations. The role that these carbene-HF complexes could play in 1,1-HF elimination reactions is discussed.

The effects of maternal and post-weaning diet interaction on glucose metabolism and gut microbiota in male mice offspring

PubMed Central

Zheng, Jia; Xiao, Xinhua; Zhang, Qian; Yu, Miao; Xu, Jianping; Qi, Cuijuan; Wang, Tong

2016-01-01

Substantial studies demonstrated that maternal nutrition can significantly determine the susceptibility to developing some metabolic diseases in offspring. However, investigations into the later-life effects of these diets on gut microbiota in the offspring are limited. Our objective was to explore the effects of maternal and post-weaning diet interaction on offspring's gut microbiota and glucose metabolism in later life. The male offspring of dams fed on either a high-fat (HF) diet or control (C) diet and then weaned to either a HF or C diet, generating four groups: C–C, HF–C, C–HF and HF–HF (n=8 in each group). The C–C offspring had lower body weight than C–HF group at 16 weeks of age (P<0.01) and both C–HF and HF–HF offspring had higher body weight than C–C group at 24 and 32 weeks of age (P<0.001 respectively). The blood glucose (BG) levels of the male offspring from the C and HF dams weaned HF diet were significantly higher at 30 min, 60 min and 120 min (P<0.001) after intraperitoneal glucose administration compared with those of the C–C group. The C–HF group had higher BG at 30 min than HF–HF group (P<0.01). Furthermore, area under the curve (AUC) in C–HF and HF–HF groups was also significantly larger than C–C group (P<0.001). Fasting BG and homoeostasis model assessment of insulin resistance (HOMA-IR) of the offspring were significantly higher in C–HF and HF–HF groups than C–C group at 32 weeks of age (P<0.05). Operational taxonomic unit (OTU), Chao and Shannon indexes showed a significantly lower diversity in C–HF offspring compared with HF–C and C–C groups (P<0.05). The dominant phyla of all the groups were Bacteroidetes, Firmicutes and Proteobacteria, which also showed significantly different percentages in the group (P<0.05). Furthermore, it is indicated that Lactobacillus and Bacteroides were significantly associated with glucose response to a glucose load (P<0.05). In conclusion, maternal and post-weaning diet interaction predisposes the offspring to aberrant glucose metabolism and alterations of gut microbiota in later life. Our study is novel in focusing on the effects of maternal and post-weaning diet interaction on offspring gut microbiota and glucose metabolism in later life. PMID:27129301

Eicosapentaenoic acid reduces adipocyte hypertrophy and inflammation in diet-induced obese mice in an adiposity-independent manner.

PubMed

LeMieux, Monique J; Kalupahana, Nishan S; Scoggin, Shane; Moustaid-Moussa, Naima

2015-03-01

Obesity is associated with an overexpansion of adipose tissue, along with increases in blood pressure, glycemia, inflammation, and thrombosis. Research to develop nutritional interventions to prevent or treat obesity and its associated diseases is greatly needed. Previously, we demonstrated the ability of eicosapentaenoic acid (EPA) to prevent high-fat (HF) diet-induced obesity, insulin resistance, and inflammation in mice. The objective of the current study was to determine the mechanisms mediating the anti-inflammatory and antilipogenic actions of EPA. In a previous study, male C57BL/6J mice were fed a low-fat diet (10% of energy from fat), an HF diet (45% of energy from fat), or an HF diet supplemented with EPA (45% of energy from fat; 36 g/kg EPA; HF+EPA) for 11 wk or an HF diet for 6 wk and then switched to the HF+EPA diet for 5 wk. In this study, we used histology/immunohistochemistry, gene expression, and metabolomic analyses of white adipose tissue from these mice. In addition, cultured mouse 3T3-L1 adipocytes were treated with 100 μM EPA for 48 h and then used for extracellular flux assays with untreated 3T3-L1 adipocytes used as a control. Compared with the HF diet, the HF+EPA diet significantly reduced body weight, adiposity, adipocyte size, and macrophage infiltration into adipose tissue. No significant differences in overall body weight or fat pad weights were observed between HF-fed mice vs. those fed the HF+EPA diet for a short time after first inducing obesity with the HF diet. Interestingly, both histology and immunohistochemistry results showed a significantly lower mean adipocyte size and macrophage infiltration in mice fed the HF diet and then switched to the HF+EPA diet vs. those fed HF diets only. This indicated that EPA was able to prevent as well as reverse HF-diet-induced adipocyte inflammation and hypertrophy and that some of the metabolic effects of EPA were independent of body weight or adiposity. In addition, adipose tissue metabolomic data and cultured adipocyte extracellular flux bioenergetic assays indicated that EPA also regulated mitochondrial function by increasing fatty acid oxidation and oxygen consumption, respectively. With the use of mice and cultured adipocytes, we showed that EPA ameliorates HF-diet effects at least in part by increasing oxygen consumption and fatty acid oxidation and reducing adipocyte size, adipogenesis, and adipose tissue inflammation, independent of obesity. © 2015 American Society for Nutrition.

ID ICPMS Lu-Hf Geochronology of Apatite from Iron-Oxide Apatite (IOA) Deposits, Northern Chilean Iron Belt.

NASA Astrophysics Data System (ADS)

Zhang, C.; Vervoort, J. D.; Barra, F.; Palma, G.

2017-12-01

Determining the age of mineralization of ore deposits is important for understanding the mechanisms and timing of ore formation. In many cases, however, conventional dateable mineral phases (e.g., zircon, monazite) are lacking in the ore mineral assemblages. For example, Iron Oxide Apatite (IOA) and Iron Oxide Gold Copper Gold (IOCG) deposits have the remaining fundamental question as to whether they have formed by hydrothermal or magmatic processes, or some combination of the two. In these deposits, the mineralization of iron oxide is often accompanied by the growth of apatites, which typically have REE concentrations of tens to several thousand ppm and which makes them potentially amenable to dating by the Lu-Hf isochron method. These apatites, however, also have very low concentrations of Hf, which makes determination of precise Hf isotope compositions challenging. In this study, we attempted to date these deposits using the apatite Lu-Hf isochron method, using procedures modified from that of Münker et al., 2001 and Barfod et al., 2003 and report the first Lu-Hf ages for apatites from Carmen, Fresia, and Mariela IOA deposits in northern Chilean Iron Belt. The concentration of Hf in analyzed apatite is 0.001 ppm. To ensure at least 0.5ng of Hf is collected for MS analysis, 0.5g apatite was dissolved for each sample. A single stage of Ln-spec resin chromatographic columns was used to separate Hf from REEs as multi stages of separation columns would decrease the Hf yield considerably. Using these procedures, we determined a Lu-Hf apatite age for the Carmen deposit of 130.0±1.7 Ma, which is in accordance with a previously published U-Pb apatite age of 131.0±1.0 Ma (Gelcich et al., 2005). The apatites from Fresia and Mariela yield Lu-Hf ages of 132.8±5.3 Ma and 117.3±0.4 Ma respectively. The lower points on the isochrons are either a low Lu/Hf phase (actinolite, magnetite) or bulk earth ratios. These are some of the first Lu-Hf ages of directly dating apatite in the ore mineralization, and show the potential in apatite Lu-Hf geochronology. However, further work needs to be done on the chemical procedure to improve the Hf yield and lower the interferences in order to make this a more routine technique of dating ore deposits.

Usefulness of Iron Deficiency Correction in Management of Patients With Heart Failure [from the Registry Analysis of Iron Deficiency-Heart Failure (RAID-HF) Registry].

PubMed

Wienbergen, Harm; Pfister, Otmar; Hochadel, Matthias; Michel, Stephan; Bruder, Oliver; Remppis, Björn Andrew; Maeder, Micha Tobias; Strasser, Ruth; von Scheidt, Wolfgang; Pauschinger, Matthias; Senges, Jochen; Hambrecht, Rainer

2016-12-15

Iron deficiency (ID) has been identified as an important co-morbidity in patients with heart failure (HF). Intravenous iron therapy reduced symptoms and rehospitalizations of iron-deficient patients with HF in randomized trials. The present multicenter study investigated the "real-world" management of iron status in patients with HF. Consecutive patients with HF and ejection fraction ≤40% were recruited and analyzed from December 2010 to October 2015 by 11 centers in Germany and Switzerland. Of 1,484 patients with HF, iron status was determined in only 923 patients (62.2%), despite participation of the centers in a registry focusing on ID and despite guideline recommendation to determine iron status. In patients with determined iron status, a prevalence of 54.7% (505 patients) for ID was observed. Iron therapy was performed in only 8.5% of the iron-deficient patients with HF; 2.6% were treated with intravenous iron therapy. The patients with iron therapy were characterized by a high rate of symptomatic HF and anemia. In conclusion, despite strong evidence of beneficial effects of iron therapy on symptoms and rehospitalizations, diagnostic and therapeutic efforts on ID in HF are low in the actual clinical practice, and the awareness to diagnose and treat ID in HF should be strongly enforced. Copyright © 2016 Elsevier Inc. All rights reserved.

Solar radio-transmitters on snail kites in Florida

USGS Publications Warehouse

Snyder, N.F.R.; Beissinger, S.R.; Fuller, M.R.

1989-01-01

The effectiveness and safety of one- and two-stage solar radio-transmitters in tracking the movements and survival of adult and fledgling Snail Kites (Rostrhamus sociabilis) were evaluated between 1979 and 1983 in southern Florida. Transmitters were attached to birds with back-pack arrangements using teflon ribbon straps. Accessory plastic shields minimized feather coverage of the solar cells. Intact transmitters were seen on birds up to 47 mo after installation. Operating lives ranged from 8 to 21 mo for one-stage, and 10 to 14 mo for two-stage transmitters. Because survival of adult and nestling radio-marked kites was high, we conclude that our transmitter-attachment method had little effect on the birds.

Nutritional Interventions in Heart Failure: Challenges and Opportunities.

PubMed

Kerley, Conor P

2018-06-01

There is a growing body of evidence that nutritional factors influence the incidence of heart failure (HF). The current manuscript aims to collate evidence relating to nutritional intervention in the treatment of HF as well as to provide context regarding challenges and opportunities in the field. Despite the accepted importance of nutritional factors relating to cardiovascular disease severity, there is surprisingly little human intervention research regarding dietary intake and HF. Further, existing nutritional interventions in HF were mostly pilot studies with small samples and short follow-up. There is consistent evidence that nutritional factors majorly influence HF. Despite limited research, there is evidence that nutritional modification can rapidly and profoundly influence multiple aspects of HF. There is an urgent need for well-conducted research to ascertain if nutritional modification can alter the long-term course of HF.

An improved method for emergent decontamination of ocular and dermal hydrofluoric acid splashes.

PubMed

Soderberg, Kjell; Kuusinen, Petri; Mathieu, Laurence; Hall, Alan H

2004-08-01

Accidental hydrofluoric acid (HF) splashes often occur in industrial settings. HF easily penetrates into tissues by initial acid action allowing fluoride ions to penetrate deeply, chelating calcium and magnesium. Resultant hypocalcemia and hypomagnesemia can be fatal. This report describes the utilization of Hexafluorine--a hypertonic, amphoteric, chelating decontamination solution--in workplaces where water decontamination followed by calcium gluconate inunction failed to prevent HF burns and systemic toxicity. Between 1998 and 1999, 16 cases of ocular and dermal HF splashes with either 70% HF or 6% HF/15% nitric acid (HNO3) were decontaminated with Hexafluorine at the worksite. HF burns did not develop and medical treatment other than initial decontamination was not reQuired in 12/16 (75%). In 7/16 (44%) cases, lost work time corresponded to duration of hospital observation (mean < 1 d).

Bardoxolone methyl prevents the development and progression of cardiac and renal pathophysiologies in mice fed a high-fat diet.

PubMed

Camer, Danielle; Yu, Yinghua; Szabo, Alexander; Wang, Hongqin; Dinh, Chi H L; Huang, Xu-Feng

2016-01-05

Obesity caused by the consumption of a high-fat (HF) diet is a major risk factor for the development of associated complications, such as heart and kidney failure. A semi-synthetic triterpenoid, bardoxolone methyl (BM) was administrated to mice fed a HF diet for 21 weeks to determine if it would prevent the development of obesity-associated cardiac and renal pathophysiologies. Twelve week old male C57BL/6J mice were fed a lab chow (LC), HF (40% fat), or a HF diet supplemented with 10 mg/kg/day BM in drinking water. After 21 weeks, the left ventricles of hearts and cortex of kidneys of mice were collected for analysis. Histological analysis revealed that BM prevented HF diet-induced development of structural changes in the heart and kidneys. BM prevented HF diet-induced decreases in myocyte number in cardiac tissue, although this treatment also elevated cardiac endothelin signalling molecules. In the kidneys, BM administration prevented HF diet-induced renal corpuscle hypertrophy and attenuated endothelin signalling. Furthermore, in both the hearts and kidneys of mice fed a HF diet, BM administration prevented HF diet-induced increases in fat accumulation, macrophage infiltration and tumour necrosis factor alpha (TNFα) gene expression. These findings suggest that BM prevents HF diet-induced developments of cardiac and renal pathophysiologies in mice fed a chronic HF diet by preventing inflammation. Moreover, these results suggest that BM has the potential as a therapeutic for preventing obesity-induced cardiac and renal pathophysiologies. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Wheel running decreases palatable diet preference in Sprague-Dawley rats.

PubMed

Moody, Laura; Liang, Joy; Choi, Pique P; Moran, Timothy H; Liang, Nu-Chu

2015-10-15

Physical activity has beneficial effects on not only improving some disease conditions but also by preventing the development of multiple disorders. Experiments in this study examined the effects of wheel running on intakes of chow and palatable diet e.g. high fat (HF) or high sucrose (HS) diet in male and female Sprague-Dawley rats. Experiment 1 demonstrated that acute wheel running results in robust HF or HS diet avoidance in male rats. Although female rats with running wheel access initially showed complete avoidance of the two palatable diets, the avoidance of the HS diet was transient. Experiment 2 demonstrated that male rats developed decreased HF diet preferences regardless of the order of diet and wheel running access presentation. Running associated changes in HF diet preference in females, on the other hand, depended on the testing schedule. In female rats, simultaneous presentation of the HF diet and running access resulted in transient complete HF diet avoidance whereas running experience prior to HF diet access did not affect the high preference for the HF diet. Ovariectomy in females resulted in HF diet preference patterns that were similar to those in male rats during simultaneous exposure of HF and wheel running access but similar to intact females when running occurred before HF exposure. Overall, the results demonstrated wheel running associated changes in palatable diet preferences that were in part sex dependent. Furthermore, ovarian hormones play a role in some of the sex differences. These data reveal complexity in the mechanisms underlying exercise associated changes in palatable diet preference. Published by Elsevier Inc.

Implication of fermentable carbohydrates targeting the gut microbiota on conjugated linoleic acid production in high-fat-fed mice.

PubMed

Druart, Céline; Neyrinck, Audrey M; Dewulf, Evelyne M; De Backer, Fabienne C; Possemiers, Sam; Van de Wiele, Tom; Moens, Frédéric; De Vuyst, Luc; Cani, Patrice D; Larondelle, Yvan; Delzenne, Nathalie M

2013-09-28

In vitro experiments have shown that isolated human gut bacteria are able to metabolise PUFA into conjugated PUFA like conjugated linoleic acids (CLA). The hypothesis of the present paper was that high-fat (HF) diet feeding and supplementation with fermentable carbohydrates that have prebiotic properties modulate the in vivo production of CLA by the mouse gut microbiota. Mice were treated for 4 weeks as follows: control (CT) groups were fed a standard diet; HF groups were fed a HF diet rich in linoleic acid (18 : 2n-6); the third groups were fed with the HF diet supplemented with either inulin-type fructans (HF-ITF) or arabinoxylans (HF-Ax). HF diet feeding increased rumenic acid (cis-9,trans-11-18 : 2 CLA) content both in the caecal and liver tissues compared with the CT groups. ITF supplementation had no major effect compared with the HF diet whereas Ax supplementation increased further rumenic acid (cis-9,trans-11-18 : 2 CLA) in the caecal tissue. These differences between both prebiotics may be linked to the high fat-binding capacity of Ax that provides more substrates for bacterial metabolism and to differential modulation of the gut microbiota (specific increase in Roseburia spp. in HF-Ax v. HF). In conclusion, these experiments supply the proof of concept that the mouse gut microbiota produces CLA in vivo, with consequences on the level of CLA in the caecal and liver tissues. We postulate that the CLA-producing bacteria could be a mediator to consider in the metabolic effects of both HF diet feeding and prebiotic supplementation.

Long-term feeding of red algae (Gelidium amansii) ameliorates glucose and lipid metabolism in a high fructose diet-impaired glucose tolerance rat model.

PubMed

Liu, Hshuan-Chen; Chang, Chun-Ju; Yang, Tsung-Han; Chiang, Meng-Tsan

2017-07-01

This study was designed to investigate the effect of Gelidium amansii (GA) on carbohydrate and lipid metabolism in rats with high fructose (HF) diet (57.1% w/w). Five-week-old male Sprague-Dawley rats were fed a HF diet to induce glucose intolerance and hyperlipidemia. The experiment was divided into three groups: (1) control diet group (Con); (2) HF diet group (HF); and (3) HF with GA diet group (HF + 5% GA). The rats were fed the experimental diets and drinking water ad libitum for 23 weeks. The results showed that GA significantly decreased retroperitoneal fat mass weight of HF diet-fed rats. Supplementation of GA caused a decrease in plasma glucose, insulin, tumor necrosis factor-α, and leptin. HF diet increased hepatic lipid content. However, intake of GA reduced the accumulation of hepatic lipids including total cholesterol (TC) and triglyceride contents. GA elevated the excretion of fecal lipids and bile acid in HF diet-fed rats. Furthermore, GA significantly decreased plasma TC, triglyceride, low density lipoprotein plus very low density lipoprotein cholesterol, and TC/high density lipoprotein cholesterol ratio in HF diet-fed rats. HF diet induced an in plasma glucose and an impaired glucose tolerance, but GA supplementation decreased homeostasis model assessment equation-insulin resistance and improved impairment of glucose tolerance. Taken together, these results indicate that supplementation of GA can improve the impairment of glucose and lipid metabolism in an HF diet-fed rat model. Copyright © 2016. Published by Elsevier B.V.

Nurse-led Multidisciplinary Heart Failure Group Clinic Appointments: Methods, Materials and Outcomes Used in the Clinical Trial

PubMed Central

Smith, C. E.; Piamjariyakul, U.; Dalton, K. M.; Russell, C.; Wick, J.; Ellerbeck, E.F.

2015-01-01

Background The Self-Management and Care of Heart Failure through Group Clinics Trial (SMAC-HF) evaluated the effects of multidisciplinary group clinic appointments on self-care skills and rehospitalizations in high risk heart failure (HF) patients. Objective The purpose of this article is to: (1) describe key SMAC-HF group clinic interactive learning strategies; (2) describe resources and materials used in the group clinic appointment; and (3) present results supporting this patient-centered group intervention. Methods This clinical trial included 198 HF patients (randomized to either group clinical appointments or to standard care). Data were collected from 72 group clinic appointments via patients’: (1) group clinic session evaluations; (2) HF Self-Care Behaviors Skills; (3) HF related discouragement and quality of life scores and (4) HF related reshopitalizations during the 12 month follow-up. Also the costs of delivery of the group clinical appointments were tabulated. Results Overall, patients rated group appointments as 4.8 out of 5 on the “helpfulness” in managing HF score. The statistical model showed a 33% decrease in the rate of rehospitalizations (incidence rate ratio (IRR) = 0.67) associated with the intervention over the 12-month follow-up period when compared with control patients (χ2(1) = 3.9, p = 0.04). The total cost for implementing five group appointments was $243.58 per patient. Conclusion The intervention was associated with improvements in HF self-care knowledge and home care behavior skills and managing their for HF care. In turn, better self-care was associated with reductions in HF related hospitalizations. PMID:25774836

Development of a practice tool for community-based nurses: the Heart Failure Palliative Approach to Care (HeFPAC).

PubMed

Strachan, Patricia H; Joy, Cathy; Costigan, Jeannine; Carter, Nancy

2014-04-01

Patients living with advanced heart failure (HF) require a palliative approach to reduce suffering. Nurses have described significant knowledge gaps about the disease-specific palliative care (PC) needs of these patients. An intervention is required to facilitate appropriate end-of-life care for HF patients. The purpose of this study was to develop a user-friendly, evidence-informed HF-specific practice tool for community-based nurses to facilitate care and communication regarding a palliative approach to HF care. Guided by the Knowledge to Action framework, we identified key HF-specific issues related to advanced HF care provision within the context of a palliative approach to care. Informed by current evidence and subsequent iterative consultation with community-based and specialist PC and HF nurses, a pocket guide tool for community-based nurses was created. We developed the Heart Failure Palliative Approach to Care (HeFPAC) pocket guide to promote communication and a palliative approach to care for HF patients. The HeFPAC has potential to improve the quality of care and experiences for patients with advanced HF. It will be piloted in community-based practice and in a continuing education program for nurses. The HeFPAC pocket guide offers PC nurses a concise, evidence-informed and practical point-of care tool to communicate with other clinicians and patients about key HF issues that are associated with improving disease-specific HF palliative care and the quality of life of patients and their families. Pilot testing will offer insight as to its utility and potential for modification for national and international use.

Ginsenoside Rb1 inhibits autophagy through regulation of Rho/ROCK and PI3K/mTOR pathways in a pressure-overload heart failure rat model.

PubMed

Yang, Tianrui; Miao, Yunbo; Zhang, Tong; Mu, Ninghui; Ruan, Libo; Duan, Jinlan; Zhu, Ying; Zhang, Rongping

2018-06-01

This study was designed to explore the relationship between ginsenoside Rb1 (Grb1) and high-load heart failure (HF) in rats. The parameters of cardiac systolic function (left ventricular posterior wall thickness (LVPWT), left ventricular internal diastolic diameter (LVID), fraction shortening (FS) and mitral valves (MVs)) of rat hearts in each group were inspected by echocardiogram. The expressions of rat myocardial contractile proteins, autophagy-related proteins and the activation of Rho/ROCK and PI3K/mTOR pathways were detected by Western blot. LVPWT, FS, MVs and the expression of myocardial contractile proteins α-MHC, apoptosis-related proteins Bcl-2 and signalling pathway involved proteins pAkt and mTOR were significantly reduced in the HF, HF+5 mg/kg Grb1 (HF+Grb1-5) and HF+Grb1+arachidonic acid (AA) groups with LVID, β-MHC, cell apoptosis, cell autophagy and Rho/ROCK significantly increased compared with the control group, of which the tendency was contrary to the HF+20 mg/kg Grb1 (HF+Grb1-20) group compared with the HF group (P < 0.05). In the HF+Grb1+AA group, there was no significant change in the above indexes compared with the HF group. The results indicated that Grb1 can exert anti-HF function by inhibiting cardiomyocyte autophagy of rats through regulation of Rho/ROCK and PI3K/mTOR pathways. © 2018 Royal Pharmaceutical Society.