Absence of ferromagnetism in Co and Mn substituted polycrystalline ZnO

We discuss the properties of semiconducting bulk ZnO when substituted with the magnetic transition metal ions Mn and Co, with substituent fraction ranging from $x$ = 0.02 to $x$ = 0.15. The magnetic properties were measured as a function of magnetic field and temperature and we find no evidence for magnetic ordering in these systems down to $T$ = 2 K. The magnetization can be fit by the sum of a Curie-Weiss term with a Weiss temperature of $\Theta\gg$100 K and a Curie term. We attribute this behavior to contributions from both \textit{t}M ions with \textit{t}M nearest neighbors and from isolated spins. This particular functional form for the susceptibility is used to explain why no ordering is observed in \textit{t}M substituted ZnO samples despite the large values of the Weiss temperature. We also discuss in detail the methods we used to minimize any impurity contributions to the magnetic signal.Comment: 6 pages, 4 figures (revised

Ionospheric effects of solar eclipses at midlatitudes

The influence of solar eclipses on the ionospheric plasma is considered based of the data of midlatitude vertical sounding stations during the entire period from the beginning of ionospheric studies in Russia. Changes in the electron density in the F and E regions during solar eclipses have been quantitatively estimated. © Pleiades Publishing, Ltd. 2009

Dilute ferrimagnetic semiconductors in Fe-substituted spinel ZnGa2_2O4_4

Solid solutions of nominal composition [ZnGa$_2$O$_4$]$_{1-x}$[Fe$_3$O$_4$]$_x$, of the semiconducting spinel ZnGa$_2$O$_4$ with the ferrimagnetic spinel Fe$_3$O$_4$ have been prepared with $x$ = 0.05, 0.10, and 0.15. All samples show evidence for long-range magnetic ordering with ferromagnetic hysteresis at low temperatures. Magnetization as a function of field for the $x$ = 0.15 sample is S-shaped at temperatures as high as 200 K. M\"ossbauer spectroscopy on the $x$ = 0.15 sample confirms the presence of Fe$^{3+}$, and spontaneous magnetization at 4.2 K. The magnetic behavior is obtained without greatly affecting the semiconducting properties of the host; diffuse reflectance optical spectroscopy indicates that Fe substitution up to $x$ = 0.15 does not affect the position of the band edge absorption. These promising results motivate the possibility of dilute ferrimagnetic semiconductors which do not require carrier mediation of the magnetic moment.Comment: 9 pages and 6 figure

Asymmetry and structural system analysis of the proximal femur meta-epiphysis: osteoarticular anatomical pathology

<p>Abstract</p> <p>Background</p> <p>The human femur is commonly considered as a subsystem of the locomotor apparatus with four conspicuous levels of organization. This phenomenon is the result of the evolution of the locomotor apparatus, which encompasses both constitutional and individual variability. The work therein reported, therefore, underlies the significance of observing anatomical system analysis of the proximal femur meta-epiphysis in normal conditions, according to the anatomic positioning with respect to the right or left side of the body, and the presence of system asymmetry in the meta-epiphysis structure, thus indicating structural and functional asymmetry.</p> <p>Methods</p> <p>A total of 160 femur bones of both sexes were compiled and a morphological study of 15 linear and angulated parameters of proximal femur epiphysis was produced, thus defining the linear/angulated size of tubular bones. The parameters were divided into linear and angulated groups, while maintaining the motion of the hip joint and transmission of stress to the unwanted parts of the limb. Furthermore, the straight and vertical diameters of the femoral head and the length of the femoral neck were also studied. The angle between the neck and diaphysis, the neck antiversion and angle of rotation of the femoral neck were subsequently measured. Finally, the condylo-diaphyseal angle with respect to the axis of extremity was determined. To visualize the force of intersystem ties, we have used the method of correlation galaxy construction.</p> <p>Results</p> <p>The absolute numeral values of each linear parameter were transformed to relative values. The values of superfluity coefficient for each parameter in the right and left femoral bone groups were estimated and Pearson's correlation coefficient has been calculated (> 0.60). Retrospectively, the observed results have confirmed the presence of functional asymmetry in the proximal femur meta-epiphysis. On the basis of compliance or insignificant difference in the confidence interval of the linear parameters, we have revealed, therefore, a discrepancy in values between the neck and the diaphysis angle and the angle of femoral neck rotation (range displacement of confident interval to a greater degree to the right).</p> <p>Conclusion</p> <p>This study assessed the observations of a systemic anatomical study encompassing the proximal femur meta-epiphysis behavior in normal condition. This work has significance in medical practice as the theoretical basis is also required in knowing the decreased frequency and degree of severity of osteoarthritic pathologies in the dominant lower extremity.</p

Louis de La Forge and the ‘Non-Transfer Argument’ for Occasionalism

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Magnetic phase diagram of cubic perovskites SrMn_1-xFe_xO_3

We combine the results of magnetic and transport measurements with Mossbauer spectroscopy and room-temperature diffraction data to construct the magnetic phase diagram of the new family of cubic perovskite manganites SrMn_1-xFe_xO_3. We have found antiferromagnetic ordering for lightly and heavily Fe-substituted material, while intermediate substitution leads to spin-glass behavior. Near the SrMn_0.5Fe_0.5O_3 composition these two types of ordering are found to coexist and affect one another. The spin glass behavior may be caused by competing ferro- and antiferromagnetic interactions among Mn^4+ and observed Fe^3+ and Fe^5+ ions.Comment: 8 pages, 10 figures, revtex, accepted to Phys. Rev.

Возможности патогенетической коррекции гиперкинетических нарушений с учетом состояния кислотно-основного баланса

As a result of analysis of the available scientific data, a significant relationship between hyperkinetic syndromes and changes in the acid-base state has been revealed. The provoking effect of alkalosis on the occurrence and severity of hyperkinetic disorders was confirmed. An own example of effective treatment of patient with essential myoclonus with taking in account his acid-base state has been given. The addition of acetylsalicylic acid to the treatment with clonazepam caused a more significant decrease in the severity of hyperkinetic disorders and improved the patient’s general condition and his quality of life. So that we suggest studying of acid-base balance in patients with hyperkinetic syndromes and syndrome of increased neuromuscular excitability in the outpatient setting and in hospital conditions at the making of initial diagnosis, and also recommend studying of acid-base balance in patients who already have neurological diagnoses, if such a study has not been made previously. Correction of acid-base status in the treatment of patients with hyperkinetic syndromes and the syndrome of increased neuromuscular excitability contributes to greater effectiveness of therapy than just symptomatic treatment of hyperkinetic disorders.В результате анализа имеющихся научных данных выявлена существенная взаимосвязь между гиперкинетическими синдромами и изменениями кислотноосновного состояния. Подтверждено провоцирующее действие алкалоза на возникновение и выраженность гиперкинетических нарушений. Приведен собственный пример эффективного лечения пациента с эссенциальной миоклонус с учетом его кислотно-основного состояния. Авторы предлагают изучать кислотно-основного баланс у пациентов с гиперкинетическими синдромами и синдромом повышенной нервно-мышечной возбудимости в амбулаторных и в стационарных условиях при постановке первоначального диагноза, а также рекомендуют такого рода диагностику для пациентов, уже имеющих неврологические диагнозы. Коррекция кислотноосновного состояния способствует большей эффективности терапии, чем просто симптоматическое лечение таких нарушений