On the suitability of baked clay for archaeomagnetic studies as deduced from detailed rock-magnetic studies

Extensive rock-magnetic investigations have been carried out on baked clays from four kilns (two from Bulgaria and two from Switzerland) found in archaeological sites of different age. Knowledge of the magnetic characteristics of the grains responsible for the archaeomagnetic signal enables us to determine which baked clays have the stablest magnetization and why this is so. This is important in directional studies, but even more so in painstaking palaeointensity studies that require a very careful evaluation of the suitability of the burnt clay material. The proposed rock-magnetic experiments enable the identification of the carriers responsible for the remanence and an adequate interpretation of the experimental results connected with the palaeointensity evaluation. The experimental methods employed are illustrated with the particular results obtained from each of the four kilns studied. The preliminary elucidation of the magnetic mineralogy of the archaeological samples helps first by obtaining a more reliable palaeointensity result, and secondly by explaining some of the discrepancies in the palaeodirectional results. Examples of successful and failed palaeointensity experiments are given in relation to the magnetic properties previously established for each oven. The burnt-clay materials in this present study satisfy the essential condition of carrying a thermoremanence. In spite of that, it is shown that there are many factors that can produce undesirable magnetic properties and thus restrict the suitability of these materials for archaeomagnetic analysis. The most important factors influencing the magnetic behaviour during magneto-diagnostic experiments are: the degree of heating in antiquity, the initial composition of the unbaked material and the burial conditions. The large difference in heating temperatures within a particular archaeological feature is a major cause of variation in magnetic behaviour amongst individual specimens, and so preventing a successful pre-selection of specimens for palaeointensity experiments. Nevertheless, the study has shown a very good coincidence between the determined rock-magnetic characteristics and the success rate in palaeointensity evaluatio

Modeling ring current ion and electron dynamics and plasma instabilities during a high‐speed stream driven storm

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94593/1/jgra21840.pd

Simulations of inner magnetosphere dynamics with an expanded RAM-SCB model and comparisons with Van Allen Probes observations

Abstract Simulations from our newly expanded ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB), now valid out to 9 R E, are compared for the first time with Van Allen Probes observations. The expanded model reproduces the storm time ring current buildup due to the increased convection and inflow of plasma from the magnetotail. It matches Magnetic Electron Ion Spectrometer (MagEIS) observations of the trapped high-energy (\u3e50 keV) ion flux; however, it underestimates the low-energy (\u3c10 keV) Helium, Oxygen, Proton, and Electron (HOPE) observations. The dispersed injections of ring current ions observed with the Energetic particle, Composition, and Thermal plasma (ECT) suite at high (\u3e20 keV) energy are better reproduced using a high-resolution convection model. In agreement with Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations, RAM-SCB indicates that the large-scale magnetic field is depressed as close as ∼4.5 RE during even a moderate storm. Regions of electromagnetic ion cyclotron instability are predicted on the duskside from ∼6 to ∼9 RE, indicating that previous studies confined to geosynchronous orbit may have underestimated their scattering effect on the energetic particles. Key Points Expanded RAM-SCB model reproduces well high-energy (\u3e50 keV) MagEIS observations The magnetic field is depressed as close as ∼4.5 RE during even a moderate storm EMIC wave growth extends on duskside from ∼6 to ∼9 RE during storm main phase

Psychophysiological Characteristics of Children with Dyslexia

Dyslexia is a specific learning disorder that involves difficulty reading due to decoding problems for letters and words. Statistics shows that 5-10% of the general population has dyslexia. The aetiology of reading disorder supposes some biological causes and morphological markers useful in the classification and early identification of the problem.The aim of this article is to find appropriate parameters, which will be useful for early diagnosis and finding the right modalities for treatment.Our findings about QEEG characteristics are not conclusive. However, slowing of brain activity in dyslexic children appeared to be confirmed. These findings lead to the possible hypothesis of delay in neurological development of these children. Significant theta/beta ratio suggest possible comorbidity with ADHD.Further research with more children included is proposed

Extended and revised archaeomagnetic database and secular variation curves from Bulgaria for the last eight millennia

International audienceThe efforts of geophysicists to describe geomagnetic field behaviour in the past lead to creation of different geomagnetic field models. On the other hand, the established regional palaeosecular variations of geomagnetic elements are increasingly used for dating purposes in archaeology. Both of these goals can be achieved if sufficient amounts of long archaeomagnetic data sets exist for different geographical regions. The accumulation of archaeomagnetic determinations began at the middle of the last century, parallel with the progressive development of experimental methodology and acceptance criteria. The presence of great number of old determinations requires their critical assessment. The important question about the reliability of the associated dating intervals should be also re-assessed. All this requires the continuous refinement and extension of the accumulated databases. This paper presents the last synthesis of Bulgarian archaeomagnetic database and the local palaeosecular variation curves obtained using a statistical treatment based on Bayesian approach (RenCurve software). The rock-magnetic characteristics of the newly included, non-published results are summarized

Global, collisional model of high‐energy photoelectrons

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95539/1/grl8976.pd

Ring current simulations of the 90 intense storms during solar cycle 23

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94717/1/jgra19539.pd

Continued convection and the initial recovery of Dst

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94856/1/grl16086.pd

Monitoring the effect of therapy on a patient with a neuroendocrine tumor of the pancreas with PET/CT, 68Ga-DOTATATE - case report

Neuroendocrine tumors (NET) are a rare diagnosis, often without symptoms or mimicking other different symptoms. Тhey are a heterogeneous group of tumors derived from neuroendocrine cells, most commonly of the gastrointestinal tract, but may originate also from other organs including the pancreas, lungs, ovaries, thyroid, pituitary, and adrenal glands (3). Due to the difficult diagnosis, NET‘s are detected at a late stage in their development, often already locally advanced or metastasized. PET/CT with 68Gallium DOTATATE proved to be an effective imaging method not only for the primary diagnosis of NET and subsequent therapeutic behavior, but also for evaluating the effect of the treatment. (1) We present a case of a positive PET/CT scan, performed with Ga-68 DOTATATE in the topical location of the tail of the pancreas after therapy with Sandostain lar