scholarly journals Spatial and temporal characteristics of poloidal waves in the terrestrial plasmasphere: a CLUSTER case study

2007 ◽  
Vol 25 (4) ◽  
pp. 1011-1024 ◽  
Author(s):  
S. Schäfer ◽  
K. H. Glassmeier ◽  
P. T. I. Eriksson ◽  
V. Pierrard ◽  
K. H. Fornaçon ◽  
...  
Keyword(s):  
Energy Transport ◽  
Low Frequency ◽  
Harmonic Oscillation ◽  
Wave Number ◽  
Third Harmonic ◽  
Wave Resonator ◽  
Temporal Structures ◽  
Clear Identification ◽  
Field Lines

Abstract. Oscillating magnetic field lines are frequently observed by spacecraft in the terrestrial and other planetary magnetospheres. The CLUSTER mission is a very suitable tool to further study these Alfvén waves as the four CLUSTER spacecraft provide for an opportunity to separate spatial and temporal structures in the terrestrial magnetosphere. Using a large scaled configuration formed by the four spacecraft we are able to detect a poloidal Ultra-Low-Frequency (ULF) pulsation of the magnetic and electric field in order to analyze its temporal and spatial structures. For this purpose the measurements are transformed into a specific field line related coordinate system to investigate their specific amplitude pattern depending on the path of the CLUSTER spacecraft across oscillating field lines. These measurements are then compared with modeled spacecraft observations across a localized poloidal wave resonator in the dayside plasmasphere. A detailed investigation of theoretically expected poloidal eigenfrequencies allows us to specify the observed 16 mHz pulsation as a third harmonic oscillation. Based on this we perform a case study providing a clear identification of wave properties such as an spatial scale structure of about 0.67 RE, the azimuthal wave number m≈30, temporal evolution, and energy transport in the detected ULF pulsations.

scholarly journals Intermediate-<I>m</I> ULF waves generated by substorm injection: a case study

2010 ◽  
Vol 28 (8) ◽  
pp. 1499-1509 ◽  
Author(s):  
T. K. Yeoman ◽  
D. Yu. Klimushkin ◽  
P. N. Mager
Keyword(s):  
Phase Variation ◽  
Wave Activity ◽  
Wave Number ◽  
Ulf Wave ◽  
Azimuthal Wave ◽  
Azimuthal Wave Number ◽  
Source Particle ◽  
Phase Propagation ◽  
Field Lines

Abstract. A case study of SuperDARN observations of Pc5 Alfvén ULF wave activity generated in the immediate aftermath of a modest-intensity substorm expansion phase onset is presented. Observations from the Hankasalmi radar reveal that the wave had a period of 580 s and was characterized by an intermediate azimuthal wave number (m=13), with an eastwards phase propagation. It had a significant poloidal component and a rapid equatorward phase propagation (~62° per degree of latitude). The total equatorward phase variation over the wave signatures visible in the radar field-of-view exceeded the 180° associated with field line resonances. The wave activity is interpreted as being stimulated by recently-injected energetic particles. Specifically the wave is thought to arise from an eastward drifting cloud of energetic electrons in a similar fashion to recent theoretical suggestions (Mager and Klimushkin, 2008; Zolotukhina et al., 2008; Mager et al., 2009). The azimuthal wave number m is determined by the wave eigenfrequency and the drift velocity of the source particle population. To create such an intermediate-m wave, the injected particles must have rather high energies for a given L-shell, in comparison to previous observations of wave events with equatorward polarization. The wave period is somewhat longer than previous observations of equatorward-propagating events. This may well be a consequence of the wave occurring very shortly after the substorm expansion, on stretched near-midnight field lines characterised by longer eigenfrequencies than those involved in previous observations.

Do different parasite species interact in their effects on host fitness? A case study on parasites of the amphipod Paracalliope fluviatilis

Parasitology ◽  
2011 ◽  
Vol 138 (9) ◽  
pp. 1176-1182 ◽  
Author(s):  
C. A. RAUQUE ◽  
R. A. PATERSON ◽  
R. POULIN ◽  
D. M. TOMPKINS
Keyword(s):  
Parasite Species ◽  
Low Frequency ◽  
Host Population ◽  
Interactive Effects ◽  
Population Means ◽  
Significant Relationships ◽  
Coitocaecum Parvum ◽  
Paracalliope Fluviatilis ◽  
Generally True

SUMMARYThere is a gap in our understanding of the relative and interactive effects of different parasite species on the same host population. Here we examine the effects of the acanthocephalan Acanthocephalus galaxii, an unidentified cyclophyllidean cestode, and the trematodes Coitocaecum parvum and Microphallus sp. on several fitness components of the amphipod Paracalliope fluviatilis, using a combination of infection surveys and both survival and behavioural trials. In addition to significant relationships between specific parasites and measures of amphipod survival, maturity, mating success and behaviour, interactions between parasite species with respect to amphipod photophilia were also significant. While infection by either A. galaxii or C. parvum was associated with increased photophilia, such increases were negated by co-infection with Microphallus sp. We hypothesize that this is due to the more subtle manipulative effect of A. galaxii and C. parvum being impaired by Microphallus sp. We conclude that the low frequency at which such double infections occur in our sampled population means that such interactions are unlikely to be important beyond the scale of the host individual. Whether or not this is generally true, implying that parasitological models and theory based on single parasite species studies do generally hold, requires cross-species meta-analytical studies.

scholarly journals Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

2002 ◽  
Vol 20 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
R. Sridharan ◽  
C. V. Devasia ◽  
N. Jyoti ◽  
Diwakar Tiwari ◽  
K. S. Viswanathan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Solar Eclipse ◽  
Equatorial Ionosphere ◽  
Hf Radar ◽  
F Region ◽  
Large Enhancement ◽  
Temporal Structures ◽  
E Region ◽  
Field Lines ◽  
Electric Fields And Currents

Abstract. The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i) the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii) significant increase in h' F immediately following the eclipse and (iii) distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities)

Donor-acceptor complexes formed by perfluoro-organo bromides and iodides with nitrogenous and other bases. II. Band shapes and widths in the absorption spectrum of gaseous CF3I-N(CH3)3

1971 ◽  
Vol 24 (12) ◽  
pp. 2493 ◽  
Author(s):  
A Mishra ◽  
ADE Pullin
Keyword(s):  
Vibrational Mode ◽  
Low Frequency ◽  
Molecular Complexes ◽  
Wave Number ◽  
Centrifugal Distortion ◽  
Band Shape ◽  
Gaseous Mixtures ◽  
Factors Affecting ◽  
Donor Acceptor ◽  
Vibration Rotation

The absorption band centred at c. 77 cm-1 in gaseous mixtures of CF3I and N(CH3)3 previously reported and attributed to the N-I stretching mode of the complex CF3I-N(CH3)3 has been carefully re-examined. This band is of interest as an example of a low frequency ?dissociative type? vibrational mode of a weak molecular complex. The band is asymmetric and apparently structureless with a half intensity width at room temperature of 28-30 cm-1. The width of the band may be accounted for as arising from transitions vi + vi+1 where vi is the vibrational quantum number of the N-I stretching mode with vi up to c. 10 making appreciable contribution to the intensity on the low wave-number side. Centrifugal distortion in the complex is considered. Centrifugal stretching and consequent weakening of the bond may shift the band envelope 2-3 cm-1 to lower wave numbers. Assessment of these and other factors affecting the band shape suggest that the fundamental frequency is probably c. 90 cm-1. The band shape of the vibrational mode of the complex at c. 272 cm-1 is briefly discussed. Many of the considerations presented in this paper should apply to vibration-rotation band shapes in other weak molecular complexes. Some general consequences of anharmonicity for the interpretation of the spectra of weak molecular complexes are discussed.

scholarly journals Very Low Frequency Electromagnetic Induction Surveys in Hydrogeological Investigations; Case Study from Poland

2016 ◽  
Vol 64 (6) ◽  
pp. 2322-2336 ◽  
Author(s):  
Szymon Oryński ◽  
Marta Okoń ◽  
Wojciech Klityński
Keyword(s):  
Electromagnetic Induction ◽  
Low Frequency ◽  
Very Low Frequency

An Integrated Acoustic/Microseismic Approach to Monitoring Low Frequency Noise & Vibration — A Case Study

2003 ◽  
Vol 10 (1) ◽  
pp. 77-95 ◽  
Author(s):  
Ian Rushforth ◽  
Andy Moorhouse ◽  
Peter Styles
Keyword(s):  
Low Frequency ◽  
Frequency Noise ◽  
Industrial Site ◽  
Low Frequency Noise ◽  
Integrated Method ◽  
Source Determination ◽  
Vibration Problems ◽  
Noise Vibration ◽  
Technique Comparison

It is proposed that low frequency noise/vibration problems are best tackled by a combination of acoustic and microseismic methods, rather than using each method in isolation. A new integrated method was devised and it was demonstrated that ‘the whole is greater than the sum of the parts’. The benefits and versatility of the new method are illustrated with reference to a case study. Unmanned monitoring took place at several houses near to an industrial site, using a multi-channel recording technique. Comparison of various components of the sound and vibration fields in each house was then carried out, which allowed various propagation paths to be distinguished. A range of further signal processing analyses was also employed to aid source determination.

scholarly journals TRANSARCTIC PERSPECTIVES OF IBERO-AMERICA

2020 ◽  
Vol 6 (4(73)) ◽  
pp. 36-39
Author(s):  
E.O. Labeckaya
Keyword(s):  
Russian Federation ◽  
Energy Transport ◽  
The Arctic ◽  
Global Competition ◽  
Arctic Zone ◽  
Case Study Method ◽  
The Russian Federation ◽  
Transnational Space

Through the concept of transnational space and “case-study” method, the prospects for the involvement of Ibero-America in the virtual Trans-Arctic, which is turning into a geoeconomic and geopolitical "bond" of two neighboring spaces – Trans-Atlantic and Trans-Pacific – are considered. The strengthening of Iberoamerican states’ presence in the Trans-Arctic will be a factor in increasing their ratings in the global hierarchy, will provide them with new geopolitical advantages for global competition, will strengthen comprehensive security (economic, environmental, energy, transport and logistics, food, water). In the context of the Arctic interests of Ibero-America, special attention is paid to options for possible "win-win" cooperation in the Arctic zone of the Russian Federation, including taking into account the potential of BRICS and its "outreach" and "BRICS +" platforms. Highlighted fundamental legal differences between Trans-Arctic and Antarctic. The Arctic prospects of Brazil as a channel for the realization of the circumpolar interests of the Iberoamerican states are emphasized

scholarly journals “Parks Not Parkways”: Contesting Automobility in a Small Canadian City

2016 ◽  
Vol 41 (3) ◽  
pp. 399-424
Author(s):  
Jim Conley ◽  
Ole B. Jensen
Keyword(s):  
Urban Development ◽  
Green Space ◽  
Environmental Preservation ◽  
Causal Mechanisms ◽  
Theoretical Approaches ◽  
Orders Of Worth ◽  
Canadian City ◽  
Temporal Structures ◽  
Physical Attributes

This case study of a dispute over a project to construct a road through green space in a small Canadian city brings together two hitherto separate theoretical approaches to mobility disputes: "culture stories" and "regimes of engagement". The stories opponents tell, in interviews and documents, concern their mobilization against the project, the value of environmental preservation, and the costs of expanded automobility, culminating in contrasting visions of urban development. The culture stories approach examines how stories varied on a narrative dimension of informational formats, temporal structures, causal mechanisms, and plot institutionalization, and a place dimension of relational geography and physical attributes. The pragmatic conditions of the different narratives of contestation, and of the challenges faced by opponents are analysed in terms of the relation between regimes of engagement: a regime of familiarity based in slow mobilities, a regime of planned action based in automobility, and the clash of industrial and green orders of worth in a regime of justification

Logic and Effectiveness of Urban Tree Preservation: A Comparative Case Study of Charlotte and San Antonio

2021 ◽  
pp. 0160323X2110382
Author(s):  
Francine S. Romero
Keyword(s):  
San Antonio ◽  
Public Support ◽  
Comparative Case Study ◽  
Tree Protection ◽  
Logical Connection ◽  
Resource Protection ◽  
Public Recognition ◽  
Clear Identification ◽  
Sound Policy

While most U.S. cities have a tree protection policy, the subsequent impact on the reduction of canopy loss is unclear. To rectify this, I utilize a theoretically grounded framework of influence comprised of clear identification of the problem/public support, adequate resources, and sound policy logic. This is then tested in a comparative case study of Charlotte, North Carolina, and San Antonio, Texas. While Charlotte benefits from public recognition of the problem and adequate resources, its regulations are weak, lacking a logical connection to aspirational outcomes. San Antonio's regulations are stronger, but combined with weaker problem identification and resources. Through quantitative and qualitative assessments, I find that San Antonio's strict regulations may have stabilized loss rates, while Charlotte's weaker rules have not. Results highlight the importance of policy logic over other commonly suggested determinants of natural resource protection.

Rough Sea Deghosting Using Wave Heights Derived from Low Frequency Pressure Recordings - A Case Study

2004 ◽  
Author(s):  
J.O.A. Robertsson ◽  
E. Kragh ◽  
R. Laws ◽  
L. Amundsen ◽  
T. Rösten ◽  
...  
Keyword(s):  
Low Frequency ◽  
Wave Heights ◽  
Rough Sea
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