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The specific heat of a layered single crystal, , was measured in the temperature range 0.45 K-6.5 K in zero magnetic field. A -type anomaly found at is associated with a phase transition into the ordered state. The experimental values of the magnetic entropy indicate deviations from two-dimensional behaviour of the magnetic system. Honmura's model of a 2D assembly of coupled S = 1/2 Ising ferromagnetic chains was used for the specific heat data analysis. The estimated value of the intrachain interaction is and that of the interchain interaction is ; these were obtained from the fitting procedure for the ordered phase. The fit for the paramagnetic phase yields and . The comparison of the results of the analysis with theoretical calculations made on the assumption of a pure dipolar character of the magnetic correlations is discussed.

Carrageenan-induced knee joint inflammation evoked a transient spinal FOS protein expression in neurons localized in the apical region of laminae I-III with peak activity observed 2 h after inflammation. Consistent with previously published observations, paw formalin injection evoked a distinct pattern of FOS protein expression in L3-L5 spinal segments. The majority of FOS-positive neurons were localized in the superficial dorsal horn (laminae I-II). Laminae V and VI contained moderate numbers of labeled neurons and only a few labeled nuclei were visible in laminae VII-X. In contrast, ipsilateral paw formalin injection, if administered 4 h after carrageenan-induced knee inflammation, evoked significantly fewer FOS positive neurons in all laminar and segmental levels analyzed as compared with formalin injected animals but without previous knee joint inflammation. These data indicate that primary acute or subacute nociceptive input may evoke central processes that are characterized by an inducible form of central inhibition which then may serve to modulate the subsequent spinal effect of superimposed nociceptive peripheral stimulation.

The dynamic properties of the dipolar magnet CsGd(MoO4)2 have been studied. The frequency and temperature dependence of the AC susceptibility investigated in the paramagnetic region above 2 K revealed the co-existence of magnetic field induced slow and fast relaxation channels with a timescale differing by three orders of magnitude. The slow relaxation is determined by the properties of the first coordination sphere of the Gd(3+) ion and has the character of a two-phonon Orbach process. The fast relaxation is potentially attributed to a two-phonon Raman process realized via a localized phonon mode associated with the layered crystal structure. The temperature dependence of the phonon mean free path in zero magnetic field indicates significant phonon scattering below 1 K resulting from the combined effect of magnetic correlations and the scattering of dominant phonons with energies corresponding to the crystal-field levels.

The alternating susceptibility of Ho 2 Ti 2 O 7 and Ho 1.9 La 0.1 Ti 2 O 7 and specific heat of Dy 2 Ti 2 O 7 and Dy 1.9 Y 0.1 Ti 2 O 7 are reported. Temperature dependence of the relaxation time obtained from susceptibility data of both Ho 2 Ti 2 O 7 and Ho 1.9 La 0.1 Ti 2 O 7 can be described assuming thermally activated relaxation. No indication of λ -like anomaly is observed in specific heat of Dy 1.9 Y 0.1 Ti 2 O 7 . The obtained results suggest that although 5% magnetic dilution reduces the relaxation time it is not sufficient to induce long-range ordering at least down to 100 mK.

Specific-heat and susceptibility studies of powdered Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{N}}_{2}$${)}_{2}$Ni(CN${)}_{4}$ have been performed from 50 mK to 20 K, and magnetization measurements have been conducted at 4.3 K in magnetic fields up to 6 T. The results show that Ni(${\mathrm{C}}_{2}$${\mathrm{H}}_{8}$${\mathrm{N}}_{2}$${)}_{2}$Ni(CN${)}_{4}$ is an S=1 antiferromagnetic Heisenberg chain with a strong planar anisotropy. The low-temperature specific-heat data show a contribution due to magnetic excitations which are interpreted within the framework of a strong coupling theory of (anti)excitons.

We report on the specific heat, magnetization and ac susceptibility measurements of single crystals of hybrid frustrated magnets Gd(1.8)Tb(0.2)Ti(2)O(7) and Gd(1.5)Tb(0.5)Ti(2)O(7). The analysis of experimental data revealed that, although partial replacing of the Gd(3+) ions by the Tb(3+) ions in the Gd(2)Ti(2)O(7) host lattice slightly enhances antiferromagnetic coupling, as inferred from the evolution of the paramagnetic Curie-Weiss temperature, the ordering temperature gradually decreases. Paramagnetic correlations introduced by the Tb(3+) ions cause this perturbation, altering the effective further neighbor interactions and destabilizing the ground state in Gd(2)Ti(2)O(7). In addition, the low-energy states of Gd(2-x)Tb(x)Ti(2)O(7) are suggested to possess a nature different from those in parent members Tb(2)Ti(2)O(7) and Gd(2)Ti(2)O(7). Finally, the frequency-dependent magnetic susceptibility behavior in Gd(1.5)Tb(0.5)Ti(2)O(7) is consistent with the formation of a spin-glass-like state indicating a pronounced slowing down of the dynamical response of the studied hybrid magnets.

The angular dependence of electron paramagnetic resonance spectra of Cu(en)(H2O)2SO4 single crystals was studied in the X-band frequency range at temperatures 4 and 300 K. Analysis of the linewidth at 300 K revealed nice agreement with the angular variation of the g-factor. This coincidence is the manifestation of the symmetric and antisymmetric exchange coupling, as main broadening mechanisms in Cu(en)(H2O)2SO4 at high temperatures. The radical change of the angular dependence of the linewidth observed at 4 K can be ascribed to dipolar coupling.

We have transplanted encapsulated dorsal root ganglia (DRG) from adult Wistar albino rats unilaterally into partially bulbectomized (n = 20) neonatal (P3-5) rats of the same strain. Three months postoperatively the animals were perfused and their brains processed by direct thiocholine method for cholinesterases (Ch), specific acetylcholinesterase (AChE) and nonspecific butyrylcholinesterase (BuChE) or stained by Cresyl violet. Selected sections were immunohistochemically stained for olfactory marker protein (OMP). In 17 cases we found surviving transplanted DRG. Fifteen transplants were well integrated with the spared portion of the olfactory bulb (OB) as clearly demonstrated by AChE and BuChE histochemistry, while two did not integrate. Regenerated OMP positive olfactory axons originating from neuroepithelium and AChE positive fibres from OB remnant penetrated into the transplants. In one case, fibers connected with BuChE positive Schwann cells grew from the transplanted DRG into the host OB. Individual sensory neurons of the transplants revealed variable intensity of the AChE staining, thus resembling the pattern of AChE activity in normal DRG. BuChE activity was mostly localized on the surface of sensory neurons in the ring of satellite cells. Some BuChE positive blood vessels penetrated into the DRG, and were observed around sensory neurons. The results showed a considerable viability and adaptability of the sensory neurons in the new environment after a long-term transplantation.

Neutron and EPR Study of Cu(tn)Cl2 a Two-Dimensional Spatially Anisotropic Triangular-Lattice Antiferromagnet R. Tarasenkoa,∗, A. Orenda£ova, E. ƒiomar, S. Ma a2, M. Orenda£, V. Zele¬ak, V. Pavlik, K. Siemensmeyer, S. Zvyagin, J. Wosnitza, A. Feher Institute of Physics, Faculty of Science, P.J. ’afarik University, Park Angelinum 9, 041 54 Ko2ice, Slovakia Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, D-14109 Berlin, Germany Institute of Chemistry, Faculty of Science, P.J. ’afarik University, Moyzesova 11, 041 54 Ko2ice, Slovakia Institute of Experimental Physics SAS, Watsonova 47, 040 01 Ko2ice, Slovakia Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf and TU Dresden, D-01314 Dresden, Germany

The Rare-earth Based Single-ion Magnet CsNd(MoO4)2 V. Tka£a,∗, K. Tibenska, A. Orenda£ova, M. Orenda£, A. G. Anders, V. Pavlik, A. Feher Institute of Physics, Faculty of Sciences, P. J. ’afarik University, Park Angelinum 9, 041 54 Ko2ice, Slovakia Faculty of Aeronautics, Technical University, Rampova 7, 041 21 Ko2ice, Slovakia Institute of Low Temperature Physics and Engineering, Lenin Av. 47, 3 101 64 Kharkov, Ukraine Institute of Experimental Physics SAS, Watsonova 47, 040 01 Ko2ice, Slovakia

The magnetic properties of the two-dimensional Ising antiferromagnet KEr(MoO{sub 4}){sub 2} have been investigated below and above transition temperature T{sub N}{approx}0.95 K in zero field and in fields up to 6.5 T by means of elastic neutron-diffraction, heat-capacity, and magnetization measurements. The low-temperature signal recorded at 0.34 K by neutron diffraction is explained within a noncollinear magnetic structure model. However, additional contribution is also present when applying the external magnetic field along the c axis even at temperatures well above the magnetic transition temperature T{sub N}. Various explanations are discussed.

Selective neuronal vulnerability of the motor cortex, basal ganglia, brainstem, medulla, cerebellum, C6 and L6 segments of the spinal cord were studied after 15 min of cardiac arrest followed by 1 h of normoxic or hyperoxic resuscitation using the suppressive Nauta method in dogs. Hyperoxic resuscitation causes characteristic somatodendritic argyrophilia of the interneuronal pool in the spinal cord and lower medulla. Cuneate, lateral reticular, supraspinal, and caudal trigeminal nuclei as well as the dorsal and ventral respiratory neuronal groups were heavily involved. Similarly, the Purkinje cells, neurons in the middle and deep portions of the mesencephalic tectum, perirubral, pretectal, posterior commissure, middle-sized striatal and giant pyramidal (Betz's) neurons in the motor cortex became argyrophilic. Hyperoxic resuscitation versus normoxic resuscitation causes statistically significant somatodendritic argyrophilia of the dorsal respiratory group, cuneate, dorsal lateral geniculate and thalamic reticular nuclei.

The olfactory bulb is one of a few brain structures characterized by high plasticity due to the fact that new neurons are continually integrated into the olfactory bulb circuit throughout life. The new cells originate from the subventricular zone of the forebrain and migrate through the rostral migratory stream (RMS) to the olfactory bulb that also represents the first synaptic relay of the olfactory system. Data accumulating in recent years have confirmed that sensory inputs can influence the level of postnatal neurogenesis in the olfactory bulb. In this study, we studied neurogenesis in the rostral migratory stream of Wistar albino rat pups after exposure to an odor-enriched environment. The rats were olfactory stimulated twice daily with different odorants from the day of their birth up to 1, 2 or 3 weeks, respectively. Using bromodeoxyuridine, a marker of cell proliferation, we found an increased number of proliferating cells in the rostral migratory stream of rat pups submitted to olfactory stimulation. Conversely, the number of dying cells, labeled with the fluorescent dye Fluoro Jade-C, was down-regulated in groups of rats exposed to an odor-enriched environment.

Specific heat and ac magnetic susceptibility measurements, spanning low temperatures $(T\ensuremath{\ge}40\text{ }\text{mK})$ and high-magnetic fields $(B\ensuremath{\le}14\text{ }\text{T})$, have been performed on a two-dimensional (2D) antiferromagnet $\text{Cu}(\text{tn}){\text{Cl}}_{2}$ $(\text{tn}=1,3\text{-diaminopropane}={\text{C}}_{3}{\text{H}}_{10}{\text{N}}_{2})$. The compound represents a $S=1/2$ spatially anisotropic triangular antiferromagnet realized by a square lattice with nearest-neighbor $(J/{k}_{B}=3\text{ }\text{K})$, frustrating next-nearest-neighbor $(0l{J}^{\ensuremath{'}}/Jl0.6)$, and interlayer $(|{J}^{\ensuremath{''}}/J|\ensuremath{\approx}{10}^{\ensuremath{-}3})$ interactions. The absence of long-range magnetic order down to $T=60\text{ }\text{mK}$ in $B=0$ and the ${T}^{2}$ behavior of the specific heat for $T\ensuremath{\le}0.4\text{ }\text{K}$ and $B\ensuremath{\ge}0$ are considered evidence of a high degree of 2D magnetic order. In fields lower than the saturation field, ${B}_{\text{sat}}=6.6\text{ }\text{T}$, a specific heat anomaly, appearing near 0.8 K, is ascribed to bound vortex-antivortex pairs stabilized by the applied magnetic field. The resulting magnetic phase diagram is remarkably consistent with the one predicted for a square lattice without a frustrating interaction, expect that ${B}_{\text{sat}}$ is shifted to values lower than expected. Potential explanations for this observation, as well as the possibility of a Berezinski-Kosterlitz-Thouless (BKT) phase transition in a spatially anisotropic triangular magnet with the collinear N\'eel ground state, are discussed.

Temperature dependence of the heat capacity of 1ayered rare earth molybdates was measured in the temperature range from 0.4 K to 23 K. It is shown that the temperature dependence of the 1attice heat capacity can be described by the "T", where n Ο 3. It is shown that differently from KDy(ΜoO4)2 and CsDyEu(MoO4)2 for CsDy(ΜoO4)2 and CsGd(MoO4)2 we obtained the temperature term with n < 3, which can be connected with the 2D behaviour, manifested also in the so-called membrane effect.

Main goal of the diploma thesis is to describe household consumption and its survey in the Czech Republic not only from the macroeconomic but mainly from the microeconomic standpoint. Consumption expenditures are the main subject of many long-term analysis and forecasts which help by implementation of economic and politcal precautions. In connection with the historical development of statistic as a scientific disciplin there is also a significant stress on a methodical development of household budget surveys which examine consumption expenditures of different social groups and household types. After the analysis of development and structure of household consumption surveyed by National Accounts and Household Budget Surveys the attention is given also to household consumption in member states of the European Union among which is also the Czech Republic.

The concept of point-contact spectroscopy was used for a dielectric crystal (NaCl) for the first time and existence of the ballistic regime of phonons was observed. Observed peculiarities of the heat flux across the point contact can be connected with the anomalies in the phonon spectrum of NaCl.

Minocycline (MC), a second-generation tetracycline and anti-inflammatory agent reportedly provides neuroprotection following CNS injury. The objective of this study was to examine the neuroprotective effects of short and long-term MC treatment using balloon-compression spinal cord injury (SCI) in the rat. Rats subjected to SCI were treated with MC for 1 day (1DMC group; total dose 180 mg/kg) or 5 days (5DMC group; total dose 450 mg/kg) or placebo. The effects of MC treatment on locomotor recovery (BBB scale) and spinal cord white and gray matter sparing were evaluated for up to 28 days. Morphometric analysis showed that while MC treatment spared spinal cord white and gray matter rostral to the lesion epicenter in both, 1DMC and 5DMC groups, sparing of white and gray matter areas was not observed caudal to the traumatic lesion. In addition, MC treatment had no effect on final locomotor recovery. Limited improvement of spinal cord post-compression consequences raises questions about the neuroprotection efficiency of MC treatment following compression SCI in the rat.

This review surveys the main data published at the Institute of Neurobiology, Slovak Republic, pertaining to both morphological and functional observations in the olfactory bulbectomy model. The review utilized this experimental approach in homo- and heterotopic transplantations, in experiments for studying neurodegenaration/regeneration and phenomena of adult neurogenesis. The results, discussed in context of relevant literary data, indicate that the model of olfactory bulbectomy can be utilized to investigate problems not only related to the olfactory system but it can also address the problems of neuronal development, neuronal plasticity and interaction concerning the nervous system as a whole.

Crystal structure, thermodynamic properties and electron spin resonance spectra of Cu(NH3)2Ag2(CN)4 have been studied. The structure of the studied compound consists of interpenetrating wave-shaped two-dimensional (2d) arrays, in which CuN4N2 octahedra axially elongated due to the Jahn–Teller effect are linked by diamagnetic [Ag(CN)2]− anions forming a square lattice. Although the susceptibility and specific heat data confirm the existence of short-range order at about 2 K, quantitative analysis of the experimental data reveals that the magnetic behavior differs from that of the crystal structure expected for 2d Heisenberg magnet on the square lattice. Structural features responsible for the observed difference are discussed. In addition, it is suggested, that additional degrees of freedom contribute to the thermodynamic equilibrium properties in the millikelvin temperature range.

The magnetocaloric effect of polycrystalline samples of pure and Y-doped dipolar spin ice ${\mathrm{Dy}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ was investigated at temperatures from nominally $0.3\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}6\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and in magnetic fields of up to $2\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. As well as being of intrinsic interest, it is proposed that the magnetocaloric effect may be used as an appropriate tool for the qualitative study of slow relaxation processes in the spin ice regime. In the high-temperature regime the temperature change on adiabatic demagnetization was found to be consistent with previously published entropy vs temperature curves. At low temperatures $(Tl0.4\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ cooling by adiabatic demagnetization was followed by an irreversible rise in temperature that persisted after the removal of the applied field. The relaxation time derived from this temperature rise was found to increase rapidly down to $0.3\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The data near $0.3\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ indicated a transition into a metastable state with much slower relaxation, supporting recent neutron-scattering results. In addition, magnetic dilution of 50% concentration was found to significantly prolong the dynamical response in the mK temperature range, in contrast with results reported for higher temperatures at which the spin correlations are suppressed. These observations are discussed in terms of defects and loop correlations in the spin ice state.

In the current report, we summarize our findings related to the involvement of nitric oxide (NO) in the pathology of spinal cord trauma. We initially studied the distribution of nitric oxide synthase (NOS)-immunolabeled and/or nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd; which is highly colocalized with NOS)-stained somata and fibers in the spinal cord of the rabbit. Segmental and laminar distribution of NADPHd-stained neurons in the rabbit revealed a large number of NADPHd-stained neurons in the spinal cord falling into six categories, N1-N6, while others could not be classified. Large numbers of NADPHd-stained neurons were identified in the superficial dorsal horn and around the central canal. Four morphologically distinct kinds of NADPHd-stained axons 2.5-3.5 microm in diameter were identified throughout the white matter in the spinal cord. Moreover, a massive occurrence of axonal NADPHd-staining was detected in the juxtagriseal layer of the ventral funiculus along the rostrocaudal axis. The prominent NADPHd-stained fiber bundles were identified in the mediobasal and central portion of the ventral funiculus. The sulcomarginal fasciculus was found in the basal and medial portion of the ventral funiculus in all cervical and thoracic segments. Since the discovery that NO may act as a neuronal transmitter, an increasing interest has focused on its ability to modulate synaptic function. NO passes through cell membranes without specific release or uptake mechanisms inducing changes in signal-related functions by several means. In particular, the activation of the soluble guanylyl cyclases (sGC), the formation of cyclic guanosine 3',5'-monophosphate (cGMP) and the action of cGMP-dependent protein kinases has been identified as the main signal transduction pathways of NO in the nervous system including spinal cord. It is known that the intracellular level of cGMP is strictly controlled by its rate of synthesis via guanylyl cyclases (GC) and/or by the rate of its degradation via 3',5'-cyclic nucleotide phosphodiesterases (PDE). GC can be divided into two main groups, i.e., the membrane-bound or particular guanylyl cyclase (pGC) and the cytosolic or sGC. In the spinal cord, the activation of pGC has only been demonstrated for natriuretic peptides, which stimulate cGMP accumulation in GABA-ergic structures in laminae I-III of the rat cervical spinal cord. These neurons are involved in controlling the action of the locomotor circuit. In view of the abundance of NO-responsive structures in the brain, it is proposed that NO-cGMP signaling will be part of neuronal information processing at many levels. In relation to this, we found that surgically induced Th7 constriction of 24 h duration stimulated both the constitutive NOS activity and cGMP level by 120 and 131%, respectively, in non-compartmentalized white matter of Th8-Th9 segments, located just caudally to the site of injury. NO-mediated cGMP formation was only slightly increased in the dorsal funiculus of Th5-Th9 segments. There are some other sources that may influence the NO-mediated cGMP formation in spinal cord. A high level of glutamate produced at the site of the lesion and an excessive accumulation of intracellular Ca2+ may stimulate NOS activity and create suitable conditions for NO synthesis and its adverse effect on white matter. An increased interest has focused on the role of NO at the site of injury and in areas located close to the epicenter of the impact site and, in these connections an upregulation of NOS was noted in neurons and interneurons. However, the upregulation of NOS expression was also seen in interneurons located just rostrally and caudally to the lesion. A quantitative analysis of laminar distribution of multiple cauda equina constriction (MCEC) induced NADPHd-stained neurons revealed a considerable increase in these neurons in laminae VIII-IX 8h postconstriction, and a highly statistically significant increase of such neurons in laminae VII-X 5 days postconstriction in the lumbosacral segments. Concurrently, the number of NADPHd-stained neurons on laminae I-II in LS segments was greatly reduced. It is concluded that a greater understanding of NO changes after spinal cord trauma is essential for the possibility of targeting this pathway therapeutically.

Centre de Recherche en Physique du Solide, De ´partement de Physique, Universite de Sherbrooke, Que´bec, Canada J1K 2R1~Received 9 September 2003; revised manuscript received 19 December 2003; published 6 May 2004!Experimental and numerical studies of the magnetic-field dependence of the specific heat and magnetizationof single crystals of CsNiF

The specific heat of Cu(C2H8N2)Ni(CN)4 measured in the temperature range from 80 mK to 2 K revealed significant deviations from the assumed one-dimensional (1D) magnetic behaviour. The behaviour of short range correlations was described by a S = 1 2 quadratic Heisenberg antiferromagnetic model with the exchange constant J k =−180 mk . Intrachain covalent bonds are completed by bifurcated hydrogen bonds of the NH…N(C)…HN type connecting adjacent chains and creating a 2D net of exchange paths. The origin of the λ-like anomaly in the specific heat observed at 128 ± 2 mk was ascribed to the 2D–3D crossover in magnetic lattice dimensionality activated by the interlayer dipolar interaction.

We have characterized segmental and laminar distribution patterns of Fos-immunopositive (Fos-IP) neurons in spinal cord segments L3-L6 after carrageenan treatment. A large number of Fos-IP neurons was found in the medial region of the ipsilateral dorsal horn laminae I-II at 4 and 6 h postinjection (pi). At one day pi, the number of Fos-IP neurons was decreased significantly, which correlated with suppression of inflammation in the affected hind paw. Bilaterally, Fos-IP neurons reappeared in the L3-L6 spinal cord segments at 3-4 days pi, mainly in the deep laminae LV-LVI. However, signs of inflammation had distinctly attenuated. Our data indicate a biphasic trend in Fos-IP in this experimental model of inflammation.

Specific heat measurements on Ni(en)/sub 2/Ni(CN)/sub 4/ (where en=C/sub 2/H/sub 8/N/sub 2/) and Ni(en)/sub 2/Ni(CN)/sub 4//spl middot/2.51H/sub 2/O in the temperature region from 60 mK to 10 K are presented. No indication of a three-dimensional ordering is observed down to 60 mK. Both compounds appear to be good representatives of antiferromagnetic S=1 Heisenberg linear chain systems with D/k=6 K, D/|J|=10 and D/k=6.3 K, D/|J|=50, respectively. >

The results of differential scanning calorimetry (DSC) from 320 K to 870 K and specific heat measurements from 0.1 K to 2 K are reported. DSC revealed "ortho(P/mmm)-para(P4/nmm)" structural phase transition at 690 K. The /spl lambda/ like anomaly in the specific heat curve at T/sub m/=0.72 K is attributed to the antiferromagnetic ordering of Dy/sup 3+/ ions and the crystalline field effect. >

Исследована температурная зависимость резонансного спектра монокристаллов [Cu(en)2H₂O]SO₄ в интервале температур 2,3-60 К на частоте ~ 73 ГГц. При температуре T > 15 К угловая зависимость спектра описывается спин-гамильтонианом аксиальной симметрии. Понижение симметрии до ромбической и расщепление резонансной линии при ориентации поля H||b, наблюдаемые при T < 15 K, обсуждаются в модели двух неэквивалентных ян-теллеровских центров, динамические искажения которых взаимно связаны в ячейке. Низкотемпературное поведение резонансной линии определяется критическим уширением в области ближнего магнитного порядка. Remove selected Досліджено температурну залежність резонансного спектра монокристалів [Cu(en)2H₂O]SO₄ в інтервалі температур 2,3–60 К на частоті ~ 73 ГГц. При температурі Т > 15 К кутова залежність спектра описується спін-гамільтоніаном аксіальної симетрії. Пониження симетрії до ромбічної і розщеплення резонансної лінії при орієнтації поля H||b, які спостерігалися при T < 15 К, обговорюються в моделі двох нееквівалентних ян-теллірівських центрів, динамічні спотворення яких взаємно зв’язані в комірці. Низько- температурна поведінка резонансної лінії визначається критичним уширенням в області ближнього магнітного порядку. The temperature dependence of the resonance spectrum of [Cu(en)2H₂O]SO₄ single crystals is investigated in the temperature range 2.3–60 K at a frequency of ∼73 GHz. At a temperature T>15 K the angular dependence of the spectrum is described by a spin Hamiltonian of axial symmetry. At T

The magnetic phase diagram of $\mathrm{KEr}({\mathrm{MoO}}_{4}{)}_{2}$ a dipolar magnetic system with strong tetragonal distortion is investigated. The analysis of the experimental results indicates that the dipolar magnet with strong tetragonal distortion in external magnetic field applied along the easy axis resembles the behavior of the $S=1/2$ two-dimensional Ising model on the rectangular lattice in $B\ensuremath{\Vert}z$ with the nearest neighbor interactions only. The Monte Carlo studies of the corresponding critical ${B}_{c}\ensuremath{-}{T}_{c}$ line revealed the second order character of the phase transitions down to the critical temperature $\ensuremath{\approx}0.7 \mathrm{K}$ and critical field ${B}_{c}\ensuremath{\approx}50 \mathrm{mT}.$ The behavior of experimental and numerical data at lower critical temperatures suggests the vicinity of a tricritical point ${T}_{T}$ characteristic for metamagnets.

Single or double-level compression of the lumbosacral nerve roots located in the dural sac results in a polyradicular symptomatology clinically diagnosed as cauda equina syndrome. The cauda equina nerve roots provide the sensory and motor innervation of most of the lower extremities, the pelvic floor and the sphincters. Therefore, in a fully developed cauda equina syndrome, multiple signs of sensory disorders may appear. These disorders include low-back pain, saddle anesthesia, bilateral sciatica, then motor weakness of the lower extremities or chronic paraplegia and, bladder dysfunction. Multiple etiologies can cause the cauda equina syndrome. Among them, non-neoplastic compressive etiologies such as herniated lumbosacral discs and spinal stenosis and spinal neoplasms play a significant role in the development of the cauda equina syndrome. Non-compressive etiologies of the cauda equina syndrome include ischemic insults, inflammatory conditions, spinal arachnoiditis and other infectious etiologies. The use of canine, porcine and rat models mimicking the cauda equina syndrome enabled discovery of the effects of the compression on nerve root neural and vascular anatomy, the impairment of impulse propagation and the changes of the neurotransmitters in the spinal cord after compression of cauda equina. The involvement of intrinsic spinal cord neurons in the compression-induced cauda equina syndrome includes anterograde, retrograde and transneuronal degeneration in the lumbosacral segments. Prominent changes of NADPH diaphorase exhibiting, Fos-like immunoreactive and heat shock protein HSP72 were detected in the lumbosacral segments in a short-and long-lasting compression of the cauda equina in the dog. Developments in the diagnosis and treatment of patients with back pain, sciatica and with a herniated lumbar disc are mentioned, including many treatment options available.

Segmental and laminar distribution of Fos-like immunoreactive, reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd)-exhibiting and double-labeled (Fos-like immunoreactive and NADPHd-exhibiting) neurons was examined in lower lumbar and sacral segments of the dog spinal cord using the model of multiple cauda equina constrictions. NADPHd histochemistry was used as marker of nitric oxide synthase-containing neurons. The appearance and the time-course of Fos-like immunoreactive, NADPHd and double-labeled neurons was studied at 2 h and 8 h postconstriction characterized as the incipient phase of cauda equina syndrome. The occurrence of Fos-like immunoreactive and NADPHd-exhibiting neurons in fully developed cauda equina syndrome was studied at five days postconstriction. An increase in Fos-like immunoreactivity in superficial laminae (I-II) and an enhanced NADPHd staining of lamina VIII neurons were found. A statistically significant increase in Fos-like immunoreactive neurons was found in laminae I-II and VIII-X 8 h postconstriction, and in contrast, a prominent decrease in Fos-like immunoreactive neurons was found in laminae I-II, accompanied by a statistically significant increase in Fos-like immunoreactive neurons in more ventrally located laminae VII-X at five days postconstriction. Quantitative analysis of laminar distribution of constriction-induced NADPHd-exhibiting neurons revealed a considerable increase in these neurons in laminae VIII-IX 8 h postconstriction and a statistically highly significant increase in NADPHd-exhibiting neurons in laminae VII-X five days postconstriction. Concurrently, the number of NADPHd-exhibiting neurons in laminae I-II was greatly reduced. While a low number of double-labeled neurons was found throughout the gray matter of lower lumbar and sacral segments at 2 h postconstriction, a statistically significant number of double-labeled neurons was found in lamina X 8 h and in laminae VII-X five days postconstriction. The course and distribution of anterograde degeneration resulting five days after multiple cauda equina constrictions are compared with segmental and laminar distribution of Fos-like immunoreactive and NADPHd-exhibiting neurons. Prominent involvement of the spinal cord neurons appearing in the lumbosacral segments at the early beginning and in fully developed cauda equina syndrome results in a Fos-like immunoreactivity and strongly enhanced NADPHd staining of some neuronal pools. Under such circumstances, an early cauda equina decompression surgery is advisable aimed at decreasing or preventing the derangement of the neural circuits in the lumbosacral segments.