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Background Although the clinical course of spontaneous intracranial hypotension (SIH) is generally benign, in unusual cases it can result in deterioration of consciousness. The exact mechanisms involved have not always been described in previously reported cases. Case Description Herein we describe the case of a 36-year-old man who presented complaining of orthostatic headache. Brain magnetic resonance imaging depicted typical findings associated with SIH. He initially underwent conservative treatments, but he subsequently began to exhibit deterioration of consciousness. Magnetic resonance imaging revealed progressive brain sagging, swelling of the brainstem, and focal hyperintensity in the left side of the thalamus on diffusion-weighted imaging. The vein of Galen was stretched downwards, creating a narrow angle between it and the straight sinus. We concluded that deep venous hypertension had occurred due to functional venous stenosis. He underwent epidural blood patch twice and ultimately recovered without any neurologic deficits. Conclusions SIH should be recognized as a possible cause of coma as a result of deep cerebral vein stagnation due to severe brain sagging. A change in the vein of Galen/straight sinus angle may be an anatomic marker associated with functional venous stenosis.

Background: Arteriovenous malformations (AVMs) of the superior vermis are extremely rare. Although they have a higher rate of hemorrhagic presentations than supratentorial AVMs, the surgical approaches for AVMs at this location remain controversial. Case description: We report the case of a 73-year-old man with a hemorrhagic superior vermian AVM that was treated with surgical resection through the occipital transtentorial approach (OTA). This approach, with a direct perpendicular view of the whole lesion, enabled us to control the feeding arteries safely and to finally accomplish a total resection. Conclusions: The OTA is an elegant approach for the resection of superior vermian AVMs. Detailed assessment of angiographic features is mandatory in selecting an effective and safe surgical approach for posterior fossa AVMs depending on their location. Keywords: Arteriovenous malformation, Occipital transtentorial, Posterior fossa, Superior vermian, Surgical approach

Pr T 2 Al 20 ( T =Ti, V) are ideal systems to study the quadrupole Kondo effect and quantum criticality arising from orbital degrees of freedom. The both systems have the nonmagnetic cubic Γ 3 crystal electric field ground doublet with the well separated excited state. In particular, PrV 2 Al 20 exhibits anomalous metallic behavior above and below the multipolar ordering temperatures, reflecting the even stronger hybridization between f and conduction electrons possibly due to a proximity to an orbital quantum critical point. Here we report the anomalous metallic behaviors found in a pure single crystal of PrV 2 Al 20 . Our detailed analyses revealed that the resistivity indicates power law temperature dependence proportional to T 3 . Furthermore, we pointed out that the 4 f electron contribution to the specific heat also exhibits power law behavior proportional to T 4 . Both observations are in a sharp contrast to the gapped behavior found in PrTi 2 Al 20 and indicate the strong c – f hybridization and strong orbital fluctuations in PrV 2 Al 20 . In addition, the 4 f electron contribution to the entropy in PrV 2 Al 20 reaches only 50% of R ln 2 at an orbital ordering at T =0.75 K, suggesting another 50% of R ln 2 expected for Γ 3 doublet is already released at higher temperature possibly due to quadrupole Kondo effect.

This paper reports a detailed buckling analysis of a free-standing annular sheet subjected to partial shrinkage as one of the strategies of morphing structures, which has received considerable attention lately. The linear buckling problem can be decomposed into in-plane and out-of-plane deformations. The in-plane (Lame) problem is first analysed to determine the stress distribution and show that in-plane hoop compression due to the competition between shrinkage and non-shrinkage zones can induce buckling despite free boundary conditions at the edges of the sheet. Subsequently, buckling analysis is performed to numerically determine buckling strains, to explore the effect of material and geometrical parameters on their buckling thresholds. A simple scaling argument is used to demonstrate that minimised (critical) buckling strain to the shrinkage radius is obtained when the shrinkage area corresponds to the non-shrinkage area. The results demonstrate that critical buckling mode can switch from a saddle to ripple mode when Young’s modulus in the shrinkage zone is approximately ten times that of the non-shrinkage zone, depending on the shrinkage size and radius ratio of the annuli.

Elongation and bending of the basilar artery are frequently observed in both normal and pathological subjects. However, their mechanism of generation remain unclear. In the present study, we measured basilar arteries in patients and normal subjects using magnetic resonance angiography (MRA) and estimated the relationships between these anatomical changes and some factors such as age, sex and vertebral artery dominance. A total of 510 subjects underwent MRA. Basilar artery length (BAL), bending length (BL), or side of bending of basilar artery was estimated on the plain images including the basilar artery in two groups with and without vertebral union. BAL was longer in males than in females (P = 0.0009) and correlated with age (P < 0.0001) in the population with vertebral union, while BL did not differ between genders and was not correlated with age in this population. Both BAL and BL were longer in subjects with vertebral artery dominance than in subjects with equivalent-sized vertebral arteries in the population with vertebral union (P < 0.0001 and P = 0.0005). No difference in the frequency of basilar artery bending was observed between males and females and no correlation was observed between the frequency of basilar artery bending and ages in subjects without vertebral artery union. A significant negative correlation between the side of bending of the basilar artery and dominant side of vertebral arteries was found for group of all patients (P < 0.0001). BAL growth may mainly depend on aging, and the presence of vertebral artery dominance may contribute to the growth of BAL while BL growth may depend on vertebral artery dominance mainly in the contralateral direction.

We determined the pressure dependence of the superconducting transition temperature, Tc, of the organic superconductor κ-(BEDT-TTF)2Cu(SCN)2 for three different isotopic compositions using helium as a pressure medium. These measurements demonstrated that, given identical measurement conditions, the pressure dependence of Tc is independent of the isotopic composition of the material. Assuming that these isotopically different materials have an identical unit cell compressibility, it is found that for all three materials Tc scales linearly with the quasi-two-dimensional unit cell area, and is thus inversely proportional to the quasi-two-dimensional carrier density in κ-(BEDT-TTF)2Cu(SCN)2.

The dependence of the Curie temperature T c on hydrostatic pressure has been determined to 6 kbar for the ferromagnetic molecular magnets [MnR 4 TPP][TCNE] for R=OC 10 H 21 , OC 14 H 29 and F in which the magnetic moments of Mn III -ions and TCNE molecules order ferrimagnetically along chains with the appreciable separations d ≃24.2, 31.2, and 13.7 A, respectively. In all three cases, T c decreases initially with pressure but passes through a sharp minimum near 2 kbar. This anomalous behavior is likely caused by competing effects, including a possible pressure-induced lattice distortion which weakens the ferromagnetic dipolar interaction between chains.

The pseudo-1D charge-transfer salt decamethylferrocenium 2,3-dicyano-1,4-naphthoquinonide, FeCp*2[DCNQ], is an unusual metamagnet that exhibits hysteresis centered on zero applied field in the nominally antiferromagnetically ordered state due to the presence of canting. Measurements of the a.c. susceptibility in a d.c. magnetic field in a He-gas cell up to hydrostatic pressures of 5 kbar have shown an approximately linear increase in both the Neel temperature and the metamagnetic critical field with increasing pressure, consistent with increasing net antiferromagnetic interstack interactions due to decreasing interstack distances.

The magnetization of Mn2−xCoxSb system with 0⩽x⩽0.35 has been measured under high magnetic fields up to 100 T and high pressure up to 12 kbar . Mn 2 Sb is a ferrimagnet and substitution of Co for Mn at 0.18⩽x⩽0.35 results in the appearance of the spontaneous first-order magnetic phase transition from ferrimagnetic (FRI) to antiferromagnetic (AF) state at T=Tt with decreasing temperature at a critical Co concentration. Below Tt a first-order field-induced AF–FRI transition is observed at a critical field Bc. The critical field Bc is found to decrease with increasing pressure applied at T=4.2 K . The AF state which appeared for the compound with the critical concentration x=0.18 can be transformed to the FRI one by the application of the high pressure of about 16 kbar by increasing the amount of FRI phase. Using the experimental data, the magnetic phase diagrams Bc–T–x and Bc–p–x are determined. The observed magnetic properties and magnetic phase diagrams of Mn2−xCoxSb are explained by the itinerant magnetism of d-electrons and by peculiarities of electronic structure. The itinerant nature of AF–FRI transition is confirmed by specific heat measurements in AF- and field-induced FRI states.

Amorphous aluminosilicate xerogels of 9.4 mol% (15 mass%) Al 2 O 3 composition were prepared by coprecipitation under various preparation conditions to investigate their effect on the porous properties of the xerogels. The precipitates were synthesized by coprecipitation of an ethanol solution of aluminium nitrate nonahydrate (ANN) and tetraethylorthosilicate (TEOS) using conc. NH 4 OH as the precipitant. The xerogels were obtained by drying and calcining the precipitate at 300°C for 4 h. Various synthesis conditions were tried, such as changes in the precipitation method, concentration of total (ANN+TEOS), H 2 O/TEOS ratio, the mixing time of the ANN and TEOS solutions, and the amount of NH 4 OH added. Of these experimental parameters, the H 2 O/TEOS ratio and mixing time of the ANN and TEOS solutions exerted the greatest influence on the porous properties. The specific surface area, total pore volume and pore radius of the xerogels ranged from 123 to 455 m 2 g −1 , from 0.31 to 1.17 ml g −1 and from 1.8 to 20 nm, respectively. These porous properties could readily be controlled by controlling the preparation conditions of the xerogels.

The spinel series Cu 1− x Zn x Cr 2 Se 4 has been investigated by AC susceptibility measurements under applied pressures of up to 6 kbar. Applied pressure is found to cause a decrease in the antiferromagnetic ordering temperature T N (∼10% at 6 kbar). We argue that this is evidence for T N being determined by the near-neighbour coupling which in these materials is ferromagnetic, despite the overall antiferromagnetic order.

Resistivity of a Heusler-type intermetallic paramagnetic compound PrInAg2 is measured precisely down to 50 mK. An empirical equation is well determined as Δ ρ∝+ log T between 50 mK and 1 K. The system is expected as an example of the quadrupolar Kondo system, since the Pr 3+ (4f 2 ) ion in the material has a non-magnetic doublet ground state Γ3. The results are not consistent with Δρ∝±T1/2 which is expected from the single impurity quadrupolar Kondo model near the ground state.