11,970 research outputs found
Design of a New Step-like Frame FBAR for Suppression of Spurious Resonances
Film bulk acoustic wave resonators (FBARs) are of great interest for wireless applications due to its inherent advantages at microwave frequencies. However, the presence of spurious modes near the main resonance degrades the performance of resonators and requires development of new methods to suppress such unwanted modes. Different techniques are used to suppress these spurious modes. In this paper, we present design of a new step-like frame structure film bulk acoustic wave resonator operating near 1.5 GHz. The simulated results are compared with simple frame-like structure. The spurious resonances are eliminated effectively and smooth pass band is obtained with effective coupling coefficient of 5.68% and quality factor of 1800. The equivalent electrical mBVD model of the FBAR based on impedance response is also presented. These highly smooth phase response and passband skirt steepness resonators are most demanding for the design of low cost, small size and high performance filters, duplexers and oscillators for wireless systems
Co- and counter-helicity interaction between two adjacent laboratory prominences
The interaction between two side-by-side solar prominence-like plasmas has been studied using a four-electrode magnetized plasma source that can impose a wide variety of surface boundary conditions. When the source is arranged to create two prominences with the same helicity (co-helicity), it is observed that helicity transfer from one prominence to the other causes the receiving prominence to erupt sooner and faster than the transmitting prominence. When the source is arranged to create two prominences with opposite helicity (counter-helicity), it is observed that upon merging, prominences wrap around each other to form closely spaced, writhing turns of plasma. This is followed by appearance of a distinct bright region in the middle and order of magnitude higher emission of soft x rays. The four-electrode device has also been used to change the angle of the neutral line and so form more pronounced S-shapes
Modified 2D Proca Theory: Revisited Under BRST and (Anti-)Chiral Superfield Formalisms
Within the framework of Becchi-Rouet-Stora-Tyutin (BRST) approach, we discuss
mainly the fermionic (i.e. off-shell nilpotent) (anti-)BRST, (anti-)co-BRST and
some discrete dual-symmetries of the appropriate Lagrangian densities for a two
(1+1)-dimensional (2D) modified Proca (i.e. a massive Abelian 1-form) theory
without any interaction with matter fields. One of the novel observations of
our present investigation is the existence of some kinds of restrictions in the
case of our present St\"{u}ckelberg-modified version of the 2D Proca theory
which is not like the standard Curci-Ferrari (CF)-condition of a non-Abelian
1-form gauge theory. Some kinds of similarities and a few differences between
them have been pointed out in our present investigation. To establish the
sanctity of the above off-shell nilpotent (anti-)BRST and (anti-)co-BRST
symmetries, we derive them by using our newly proposed (anti-)chiral superfield
formalism where a few specific and appropriate sets of invariant quantities
play a decisive role. We express the (anti-)BRST and (anti-)co-BRST conserved
charges in terms of the superfields that are obtained after the applications of
(anti-)BRST and (anti-)co-BRST invariant restrictions and prove their off-shell
nilpotency and absolute anticommutativity properties, too. Finally, we make
some comments on (i) the novelty of our restrictions/obstructions, and (ii) the
physics behind the negative kinetic term associated with the pseudo-scalar
field of our present theory.Comment: LaTeX file, 58 pages, Journal reference give
Search for d^* Dibaryon by Double-radiative Capture on Pionic Deuterium
We report a search for d^* dibaryon production by double-radiative capture on
pionic deuterium. The experiment was conducted at the TRIUMF cyclotron using
the RMC cylindrical pair spectrometer, and detected gamma-ray coincidences
following pion stops in liquid deuterium. We found no evidence for narrow
dibaryons, and obtained a branching ratio upper limit, BR < 6.7 times 10^{-6}
(90% C.L.), for narrow d^* production in the mass range from 1920 to 1980 MeV.
Replaced with Physics Letter B accepted version and corrected normalization.Comment: 9 pages, 4 figure
Gender-based comparison of nutritional status in tribal and non-tribal populations: a study in the Udaipur region
Background: It is imperative to examine the nutritional quality of adult populations, both tribal and non-tribal, in the Udaipur region of Rajasthan in order to comprehend the health dynamics of these societies. Tribal communities frequently encounter particular difficulties with regard to healthcare access, socioeconomic standing, and cultural customs that may have an impact on their nutritional well-being that is distinct from that of non-tribal communities.
Methods: Our study group consisted of 300 tribals and 300 non tribals. The blood was tested to determine various nutritional parameters like minerals iron, calcium, phosphorus, magnesium, and vitamins like vitamin, vitamin A, vitamin D, and vitamin B12.
Results: Comparable levels of parameters like calcium, magnesium, phosphorus, vitamin A, and vitamin D3 were found in both non-tribal and tribal people, suggesting that both groups' nutritional statuses were generally similar. Non-tribal males and females exhibited significantly higher iron levels compared to their tribal counterparts. Both non-tribal males and females had considerably higher levels of vitamin C and B12 compared to tribal peers.
Conclusions: The study highlights the differences in iron, vitamin C, and vitamin B12 levels that occur in the Udaipur region between non-tribal and tribal individuals
Laboratory simulations of astrophysical jets and solar coronal loops: new results
An experimental program underway at Caltech has produced plasmas where the shape is neither fixed by the vacuum chamber nor fixed by an external coil set, but instead is determined by self-organization. The plasma dynamics is highly reproducible and so can be studied in considerable detail even though the morphology of the plasma is both complex and time-dependent. A surprising result has been the observation that self-collimating MHD-driven plasma jets are ubiquitous and play a fundamental role in the self-organization. The jets can be considered lab-scale simulations of astrophysical jets and in addition are intimately related to solar coronal loops. The jets are driven by the combination of the axial component of the JĂ—B force and the axial pressure gradient resulting from the non-uniform pinch force associated with the flared axial current density. Behavior is consistent with a model showing that collimation results from axial non-uniformity of the jet velocity. In particular, flow stagnation in the jet frame compresses frozen-in azimuthal magnetic flux, squeezes together toroidal magnetic field lines, thereby amplifying the embedded toroidal magnetic field, enhancing the pinch force, and hence causing collimation of the jet
Observational Evidence of Sausage-Pinch Instability in Solar Corona by SDO/AIA
We present the first observational evidence of the evolution of sausage-pinch
instability in Active Region 11295 during a prominence eruption using data
recorded on 12 September 2011 by the Atmospheric Imaging Assembly (AIA) onboard
the Solar Dynamics Observatory (SDO). We have identified a magnetic flux tube
visible in AIA 304 \AA\ that shows curvatures on its surface with variable
cross-sections as well as enhanced brightness. These curvatures evolved and
thereafter smoothed out within a time-scale of a minute. The curved locations
on the flux tube exhibit a radial outward enhancement of the surface of about
1-2 Mm (factor of 2 larger than the original thickness of the flux tube) from
the equilibrium position. AIA 193 \AA\ snapshots also show the formation of
bright knots and narrow regions inbetween at the four locations as that of 304
\AA\ along the flux tube where plasma emission is larger compared to the
background. The formation of bright knots over an entire flux tube as well as
the narrow regions in < 60 s may be the morphological signature of the sausage
instability. We also find the flows of the confined plasma in these bright
knots along the field lines, which indicates the dynamicity of the flux tube
that probably causes the dominance of the longitudinal field component over
short temporal scales. The observed longitudinal motion of the plasma frozen in
the magnetic field lines further vanishes the formed curvatures and plasma
confinements as well as growth of instability to stablize the flux tube.Comment: 12 pages, 5 figure
Recent trends in Molecular Imaging : PET/CT in Neurology
PET/CT is an important molecular imaging technique for the assessment ofneurological disorders. The most widely used radiopharmaceutical for both clinical and research purposes is [18F] 2-fluoro-2-deoxy-D-glucose (FDG). It is extensively used owing to its favourable physical characteristics. It enables depiction of cerebral glucose metabolism, and has thus been used to study various pathological states. Despite this, FDG has its own limitations. This is owing to its limited specificity and high cortical uptake. This has paved the way for the development of several non-FDG PET radiopharmaceuticals. We present the insights gained at our institution, using these radiotracers in the assessment of neurological disease. Our study shows that the use of FDG and non-FDG novel PET radiopharmaceuticals facilitates the early diagnosis, delineation of extent, prognostication and monitoring of therapeutic response in several neuropathological states.PET/CT is an important molecular imaging technique for the assessment ofneurological disorders. The most widely used radiopharmaceutical for both clinicaland research purposes is [18F] 2-fluoro-2-deoxy-D-glucose (FDG). It is extensivelyused owing to its favourable physical characteristics. It enables depiction of cerebralglucose metabolism, and has thus been used to study various pathological states.Despite this, FDG has its own limitations. This is owing to its limited specificity andhigh cortical uptake. This has paved the way for the development of several non-FDGPET radiopharmaceuticals. We present the insights gained at our institution, usingthese radiotracers in the assessment of neurological disease. Our study shows that theuse of FDG and non-FDG novel PET radiopharmaceuticals facilitates the earlydiagnosis, delineation of extent, prognostication and monitoring of therapeuticresponse in several neuropathological states
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