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1.
Phys Rev Lett ; 119(14): 147201, 2017 Oct 06.
Article in English | MEDLINE | ID: mdl-29053286

ABSTRACT

Inelastic neutron scattering measurements on the itinerant antiferromagnet CaCo_{2-y}As_{2} at a temperature of 8 K reveal two orthogonal planes of scattering perpendicular to the Co square lattice in reciprocal space, demonstrating the presence of effective one-dimensional spin interactions. These results are shown to arise from near-perfect bond frustration within the J_{1}-J_{2} Heisenberg model on a square lattice with ferromagnetic J_{1} and hence indicate that the extensive previous experimental and theoretical study of the J_{1}-J_{2} Heisenberg model on local-moment square spin lattices should be expanded to include itinerant spin systems.

2.
J Phys Condens Matter ; 29(13): 135601, 2017 Apr 05.
Article in English | MEDLINE | ID: mdl-28140348

ABSTRACT

The physical properties of an intermetallic compound CeRh2Ga2 have been investigated by magnetic susceptibility [Formula: see text], isothermal magnetization M(H), heat capacity [Formula: see text], electrical resistivity [Formula: see text], thermal conductivity [Formula: see text] and thermopower S(T) measurements. CeRh2Ga2 is found to crystallize with CaBe2Ge2-type primitive tetragonal structure (space group P4/nmm). No evidence of long range magnetic order is seen down to 1.8 K. The [Formula: see text] data show paramagnetic behavior with an effective moment [Formula: see text]/Ce indicating Ce3+ valence state of Ce ions. The [Formula: see text] data exhibit Kondo lattice behavior with a metallic ground state. The low-T [Formula: see text] data yield an enhanced Sommerfeld coefficient [Formula: see text] mJ/mol K2 characterizing CeRh2Ga2 as a moderate heavy fermion system. The high-T [Formula: see text] and [Formula: see text] show an anomaly near 255 K, reflecting a phase transition. The [Formula: see text] suggests phonon dominated thermal transport with considerably higher values of Lorenz number L(T) compared to the theoretical Sommerfeld value L 0.

3.
J Phys Condens Matter ; 27(43): 436001, 2015 Nov 04.
Article in English | MEDLINE | ID: mdl-26443921

ABSTRACT

Physical properties of partially Ca substituted hole-doped Dy2Ti2O7 have been investigated by ac magnetic susceptibility χ(ac)(T), dc magnetic susceptibility χ(T), isothermal magnetization M(H) and heat capacity C(p)(T) measurements on Dy1.8Ca0.2Ti2O7. The spin-ice system Dy2Ti2O7 exhibits a spin-glass type freezing behavior near 16 K. Our frequency dependent χ(ac)(T) data of Dy1.8Ca0.2Ti2O7 show that the spin-freezing behavior is significantly influenced by Ca substitution. The effect of partial nonmagnetic Ca(2+) substitution for magnetic Dy(3+) is similar to the previous study on nonmagnetic isovalent Y(3+) substituted Dy(2-x)Y(x) Ti2O7 (for low levels of dilution), however the suppression of spin-freezing behavior is substantially stronger for Ca than Y. The Cole-Cole plot analysis reveals semicircular character and a single relaxation mode in Dy1.8Ca0.2Ti2O7 as for Dy2Ti2O7. No noticeable change in the insulating behavior of Dy2Ti2O7 results from the holes produced by 10% Ca(2+) substitution for Dy(3+) ions.

4.
J Phys Condens Matter ; 27(20): 206002, 2015 May 27.
Article in English | MEDLINE | ID: mdl-25950731

ABSTRACT

Antiferromagnetic ordering of EuCu2Sb2 which forms in the tetragonal CaBe2Ge2-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and (151)Eu Mössbauer spectroscopy. The room temperature (151)Eu isomer shift of -12.8(1) mm s(-1) shows the Eu to be divalent, while the (151)Eu hyperfine magnetic field (B(hf)) reaches 28.7(2) T at 2.1 K, indicating a full Eu(2+) magnetic moment. B(hf)(T) follows a smooth S = 7/2 Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. The refined Eu magnetic moment at 0.4 K is 7.08(15) µ(B) which is the full free-ion moment expected for the Eu(2+) ion with S = 7/2 and a spectroscopic splitting factor of g = 2.

5.
J Phys Condens Matter ; 27(1): 016004, 2015 Jan 14.
Article in English | MEDLINE | ID: mdl-25493957

ABSTRACT

A Muon spin relaxation (µSR) study has been performed on the Kondo lattice heavy fermion itinerant ferromagnet CeCrGe3. Recent investigations of bulk properties have revealed a long-range ordering of Cr moments at Tc = 70 K in this compound. Our µSR investigation between 1.2 K and 125 K confirm the bulk magnetic order which is marked by a loss in initial asymmetry below 70 K accompanied with a sharp increase in the muon depolarization rate. Field dependent µSR spectra show that the internal field at the muon site is higher than 0.25 T apparently due to the ferromagnetic nature of ordering. The effect of Ti substitution on the magnetism in CeCrGe3 is presented. A systematic study has been made on polycrystalline CeCr(1-x)Ti(x)Ge3 (0 ⩽ x ⩽ 1) using magnetic susceptibility χ(T), isothermal magnetization M(H), specific heat C(T) and electrical resistivity ρ(T) measurements which clearly reveal that the substitution of Ti for Cr in CeCrGe3 strongly influences the exchange interaction and ferromagnetic ordering of Cr moments. The Cr moment ordering temperature is suppressed gradually with increasing Ti concentration up to x = 0.50 showing Tc = 7 K beyond which Ce moment ordering starts to dominate and a crossover between Cr and Ce moment ordering is observed with a Ce moment ordering Tc = 14 K for x = 1.0. The Kondo lattice behavior is evident from temperature dependence of ρ(T) in all CeCr(1-x)Ti(x)Ge3 samples.

6.
J Phys Condens Matter ; 26(40): 405702, 2014 Oct 08.
Article in English | MEDLINE | ID: mdl-25224494

ABSTRACT

We present the superconducting and normal state properties of CaPd(2)Ge(2) single crystals investigated by magnetic susceptibility χ, isothermal magnetization M, heat capacity Cp, in-plane electrical resistivity ρ and London penetration depth λ versus temperature T and magnetic field H measurements. Bulk superconductivity is inferred from the ρ(T) and Cp(T) data. The ρ(T) data exhibit metallic behavior and a superconducting transition with T(c onset) = 1.98 K and zero resistivity at T(c 0) = 1.67 K. The χ(T) reveals the onset of superconductivity at 2.0 K. For T > 2.0 K, the χ(T) and M(H) are weakly anisotropic paramagnetic with χ(ab) > χ(c). The Cp(T) data confirm the bulk superconductivity below T(c) = 1.69(3) K. The superconducting state electronic heat capacity is analyzed within the framework of a single-band α-model of BCS superconductivity and various normal and superconducting state parameters are estimated. Within the α-model, the Cp(T) data and the ab plane λ(T) data consistently indicate a moderately anisotropic s-wave gap with Δ(0)/k(B)T(c) ≈ 1.6, somewhat smaller than the BCS value of 1.764. The relationship of the heat capacity jump at Tc and the penetration depth measurement to the anisotropy in the s-wave gap is discussed.

7.
J Phys Condens Matter ; 26(30): 306001, 2014 Jul 30.
Article in English | MEDLINE | ID: mdl-24994692

ABSTRACT

We report our comprehensive study of physical properties of a ternary intermetallic compound PrIrSi3 investigated by dc magnetic susceptibility χ(T), isothermal magnetization M(H), thermo-remnant magnetization M(t), ac magnetic susceptibility χac(T), specific heat Cp(T), electrical resistivity ρ(T), muon spin relaxation (µSR) and inelastic neutron scattering (INS) measurements. A magnetic phase transition is marked by a sharp anomaly at Ttr = 12.2 K in χ(T) measured at low applied fields which is also reflected in the Cp(T) data through a weak anomaly at 12 K. An irreversibility between the zero field cooled and field cooled χ(T) data below 12.2 K and a very large relaxation time of M(t) indicates the presence of ferromagnetic correlation. The magnetic part of specific heat shows a broad Schottky-type anomaly near 40 K due to the crystal electric field (CEF) effect. An extremely small value of magnetic entropy below 12 K suggests a CEF-split singlet ground state which is confirmed from our analysis of INS data. The INS spectra show two prominent inelastic excitations at 8.5 meV and 18.5 meV that could be well accounted by a CEF model. The CEF splitting energy between the ground state singlet and the first excited doublet is found to be 92 K. Our µSR data reveal a possible magnetic ordering below 30 K, which is much higher than that found from the specific heat and magnetic susceptibility measurements. This could be due to the presence of short range correlations well above the long range magnetic ordering or due to the electronic changes induced by muons. The induced moment magnetism in the singlet ground state system PrIrSi3 with such a large splitting energy of 92 K is quite surprising.

8.
J Phys Condens Matter ; 26(28): 286002, 2014 Jul 16.
Article in English | MEDLINE | ID: mdl-24945748

ABSTRACT

The physical properties of self-flux grown EuPd2As2 single crystals have been investigated by means of magnetization M, magnetic susceptibility χ, specific heat Cp, and electrical resistivity ρ measurements versus temperature T and magnetic field H. The crystal structure was determined using powder x-ray diffraction measurements, which confirmed the ThCr2Si2-type body-centered tetragonal structure (space group I4/mmm) reported previously. The ρ(T) data indicate that EuPd2As2 is metallic. The χ(T) data indicate that the Eu(+2) moments have spin S = 7/2 with g = 2. Long-range antiferromagnetic (AFM) ordering is apparent from the χ(T), Cp(T), and ρ(T) measurements. For H∥c the χ(T) indicates two transitions at TN1 = 11.0 K and TN2 = 5.5 K, whereas for H⊥c only one transition is observed at TN1 = 11.0 K. Between TN1 and TN2 the anisotropic χ(T) data suggest a planar noncollinear AFM structure, whereas at T < TN2 the χ(T) and M(H, T) data suggest a spin reorientation transition in which equal numbers of spins cant in opposite directions out of the ab plane. We estimate the critical field at 2 K at which all Eu moments become aligned with the field to be about 22 T. An upturn in ρ at T < TN1 suggests superzone energy gap formation below TN1. This behavior of ρ(T < TN1) is not sensitive to applied magnetic fields up to H = 12 T.


Subject(s)
Arsenic/chemistry , Crystallization , Europium/chemistry , Magnetic Fields , Palladium/chemistry , Electric Impedance , Materials Testing , Temperature
9.
Case Rep Otolaryngol ; 2013: 347325, 2013.
Article in English | MEDLINE | ID: mdl-24312739

ABSTRACT

A foreign body in the larynx is an airway emergency that requires urgent evaluation and treatment. Irregular foreign bodies tend to orient in a sagittal plane and may produce only partial obstruction, allowing adequate air movement, hence making them undetectable for a long period of time. We report a case of a laryngotracheal foreign body that remained reclusive for 9 years.

10.
J Phys Condens Matter ; 25(19): 196003, 2013 May 15.
Article in English | MEDLINE | ID: mdl-23604428

ABSTRACT

We have investigated the magnetic and transport properties of a noncentrosymmetric compound PrRhSi3 by dc magnetic susceptibility χ(T), isothermal magnetization M(H), thermoremanent magnetization M(t), specific heat Cp(T), electrical resistivity ρ(T,H) and muon spin relaxation (µSR) measurements. At low fields χ(T) shows two anomalies near 15 and 7 K with an irreversibility between ZFC and FC data below 15 K. In contrast, no anomaly is observed in Cp(T) or ρ(T) data. M(H) data at 2 K exhibit very sharp increase below 0.5 T and a weak hysteresis. M(t) exhibits very slow relaxation, typical for a spin-glass system. Even though the absence of any anomaly in Cp(T) is consistent with the spin-glass type behavior, there is no obvious origin of spin-glass behavior in this structurally well ordered compound. The crystal electric field (CEF) analysis of Cp(T) data indicates a CEF-split singlet ground state lying below a doublet at 81(1) K and a quasi-triplet at 152(2) K. The ρ(T) data indicate a metallic behavior, and ρ(H) exhibits a very high positive magnetoresistance, as high as ~300% in 9 T at 2 K. No long range magnetic order or spin-glass behavior was detected in a µSR experiment down to 1.2 K.


Subject(s)
Magnetic Fields , Praseodymium/chemistry , Rhenium/chemistry , Silicon/chemistry , Electron Transport , Materials Testing
11.
J Phys Condens Matter ; 24(45): 456003, 2012 Nov 14.
Article in English | MEDLINE | ID: mdl-23086193

ABSTRACT

We have investigated the magnetic and electronic transport properties of single crystal Pr(2)Pd(3)Ge(5) grown by the Czochralski method. Complex magnetic behaviour (multiple magnetic transitions) is clearly seen in this compound from the magnetic susceptibility χ(T), isothermal magnetization M(H) and electrical resistivity ρ(T) data. For the magnetic field applied along the crystallographic c-axis (H ‖ [001]) the χ(T) data exhibit two sharp transitions at 6.9 and 6.3 K and a broad hump near 8 K. Four anomalies at 8.0, 7.3, 6.2 and 4.9 K are observed for the magnetic field along both a- and b-directions (H ‖ [100] and H ‖ [010]). Further, the ordered state χ(T) presents a large anisotropy with an easy axis along the c-axis. The presence of magnetocrystalline anisotropy is also inferred from the isothermal M(H) data. The M(H) data measured at 1.9 K for H ‖ [001] exhibit a step-like increase due to field-induced metamagnetic transitions at [Formula: see text] T and [Formula: see text] T. For H ‖ [100] and H ‖ [010] sharp step-like field-induced metamagnetic transitions occur at [Formula: see text] T and [Formula: see text] T which are accompanied by a weak S-shaped spin-flop metamagnetic transition at [Formula: see text] T. We have extracted the H-T phase diagram from the M(H) data collected at different temperatures in the magnetically ordered state which shows the existence of three magnetic phases below T(N) for H ‖ [100] and H ‖ [010], and two magnetic phases for H ‖ [001]. A sharp transition due to the onset of long range antiferromagnetic order is also seen in the ρ(T) data which also exhibit anisotropic behaviour. The observation of an upturn near T(N) in the ρ(T) data suggests the formation of a super-zone gap and hence the existence of incommensurate magnetic structure. Further, in the ordered state, the ρ(T) data present a gap in the excitation spectrum of magnons with a characteristic energy gap Δ âˆ¼ 0.23 meV.

12.
Phys Rev Lett ; 108(8): 087005, 2012 Feb 24.
Article in English | MEDLINE | ID: mdl-22463561

ABSTRACT

The compound BaMn2As2 with the tetragonal ThCr2Si2 structure is a local-moment antiferromagnetic insulator with a Néel temperature T(N)=625 K and a large ordered moment µ=3.9µ(B)/Mn. We demonstrate that this compound can be driven metallic by partial substitution of Ba by K while retaining the same crystal and antiferromagnetic structures together with nearly the same high T(N) and large µ. Ba(1-x)K(x)Mn2As2 is thus the first metallic ThCr2Si2-type MAs-based system containing local 3d transition metal M magnetic moments, with consequences for the ongoing debate about the local-moment versus itinerant pictures of the FeAs-based superconductors and parent compounds. The Ba(1-x)K(x)Mn2As2 class of compounds also forms a bridge between the layered iron pnictides and cuprates and may be useful to test theories of high T(c) superconductivity.

13.
J Phys Condens Matter ; 23(37): 376001, 2011 Sep 21.
Article in English | MEDLINE | ID: mdl-21878715

ABSTRACT

The magnetic and transport properties of PrIr(2)B(2) and PrIr(2)B(2)C have been investigated by dc and ac magnetic susceptibility, specific heat, electrical resistivity and magnetoresistance measurements. PrIr(2)B(2) forms in CaRh(2)B(2)-type orthorhombic crystal structure (space group Fddd). At low fields the dc magnetic susceptibility of PrIr(2)B(2) exhibits a sharp anomaly near 46 K which is followed by an abrupt increase below 10 K with a peak at 6 K, and split-up in ZFC and FC data below 46 K. In contrast, the specific heat exhibits only a broad Schottky type hump near 9 K which indicates that there is no long range magnetic order in this compound. The thermo-remanent magnetization is found to decay very slowly with a mean relaxation time τ = 3917 s. An ac magnetic susceptibility measurement also observes two sharp anomalies; the peak positions strongly depend on the frequency and shift towards high temperature with an increase in frequency, obeying the Vogel-Fulcher law as expected for a canonical spin-glass system. The two spin-glass transitions occur at freezing temperatures T(f1) = 36 K and T(f2) = 3.5 K with shifts in the freezing temperatures per decade of frequency δT(f1) = 0.044 and δT(f2) = 0.09. An analysis of the frequency dependence of the transition temperature with critical slowing down, τ(max)/τ(0) = [(T(f)-T(SG))/T(SG)](-zν), gives τ(0) = 10(-7) s and exponent zν = 8, and the Vogel-Fulcher law gives an activation energy of 84 K for T(f1) and 27.5 K for T(f2). While zν = 8 is typical for spin-glass system, the characteristic relaxation time τ(0) = 10(-7) s is very large and comparable to that of superspin-glass systems. An addition of C in PrIr(2)B(2) leads to PrIr(2)B(2)C which forms in LuNi(2)B(2)C-type tetragonal structure (space group I4/mmm) and remains paramagnetic down to 2 K. The specific heat data show a broad Schottky type anomaly, which could be fairly reproduced with CEF analysis which suggests that the ground state is a CEF-split singlet and the first excited state singlet is situated 15 K above the ground state. The Sommerfeld coefficient γ∼300 mJ mol(-1) K(-2) of PrIr(2)B(2)C is very high and reflects a heavy fermion behaviour in this compound. We believe that the heavy fermion state in PrIr(2)B(2)C has its origin in low lying crystal field excitations as has been observed in PrRh(2)B(2)C.


Subject(s)
Boron/chemistry , Carbon/chemistry , Glass/chemistry , Iridium/chemistry , Praseodymium/chemistry , Crystallography, X-Ray , Magnetics , Models, Molecular , Temperature
14.
J Phys Condens Matter ; 23(27): 276001, 2011 Jul 13.
Article in English | MEDLINE | ID: mdl-21673393

ABSTRACT

We report the magnetic and transport properties of a new ternary intermetallic compound, CeRhSn3, using magnetic susceptibility, magnetization, specific heat, electrical resistivity, muon-spin relaxation (µSR) and neutron diffraction investigations. The dc magnetic susceptibility data reveal two magnetic phase transitions at 0.9 and 4 K. The overall behavior of dc susceptibility and magnetization indicates a ferrimagnetic-type phase transition near 4 K. The specific heat data also exhibit sharp λ-type anomalies at 1 and 4 K. The behavior of the specific heat anomaly under the application of a magnetic field suggests that the 1 K transition is probably related to a transition from a ferri- to a ferromagnetic state. The low temperature specific heat exhibits an enhanced Sommerfeld coefficient γ (~100 mJ mol⁻¹ K⁻²) due to the formation of a moderate heavy fermion state. The resistivity of CeRhSn3 demonstrates an interplay between the RKKY and Kondo interactions which is further modified by the presence of the crystal electric field. Interestingly, the resistivity of the nonmagnetic reference compound, LaRhSn3, is found to increase with decreasing temperature. Further, the onset of long-range magnetic order below 1 K is confirmed from our µSR study on CeRhSn3. However, the 4 K transition is not detected in the µSR and low temperature neutron diffraction data. Analysis of the dc magnetic susceptibility data within the framework of a two-sublattice model of ferrimagnetism supports the ferrimagnetic-type transition at 4 K in CeRhSn3. We have observed an unusual frequency dependence of the peak near 4 K in the ac susceptibility, which shows that the transition temperature shifts toward the lower temperature side with increasing frequency.

15.
Minim Invasive Neurosurg ; 53(4): 191-3, 2010 Aug.
Article in English | MEDLINE | ID: mdl-21132611

ABSTRACT

BACKGROUND: Nasal glioma or glial heterotopia is a rare embryologic anomaly that heralds its presence shortly after birth or in childhood. Nasal glioma in an adult is very rare, often asymptomatic and the occurrence of nasal glioma in Meckel's cave in an adult has not been previously reported. CASE REPORT: The authors encountered a case of an incidentally diagnosed Meckel's cave nasal glioma in a 40-year-old male which was successfully excised by an endonasal endoscopic transmaxillary transpterygoid approach. CONCLUSION: The occurrence of a nasal glioma in Meckel's cave an adult is very rare. Considering the deep skull base location, endonasal endoscopic surgery provides a minimal access technique to reach this location with excellent results.


Subject(s)
Dura Mater/surgery , Endoscopy , Glioma/surgery , Skull Base Neoplasms/surgery , Adult , Dura Mater/pathology , Glioma/pathology , Humans , Incidental Findings , Male , Skull Base Neoplasms/pathology , Treatment Outcome
16.
Minim Invasive Neurosurg ; 52(1): 25-31, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19247901

ABSTRACT

Neuroendoscopic procedures, particularly transnasal skull-base procedures, are currently performed with 2D endoscopes that lack stereoscopic vision and depth of field. In principal, 3D vision should be preferable to the operating surgeon, but the previously existing systems have not been adopted. We evaluated a novel 3D endoscope to compare with 2D endoscopy. 33 neurosurgeons and skull-base otolaryngologists were recruited, and randomized to complete two runs of a task-based simulator paradigm using 2D and/or 3D visualization. After the two trials, each subject completed a questionnaire assessing professional demographics and preferences for visualization. The task paradigm had objective endpoints that measured speed, efficiency, and error rates. 75% of respondents preferred 3D endoscopy, and 87.5% determined that 3D visualization either somewhat or greatly helped with the assigned tasks. In the second run, subjects using 3D demonstrated a significantly higher efficiency than subjects using 2D (p=0.04). Subjects' speed and efficiency improved significantly when moving from 2D to 3D, and speed and efficiency improved significantly from Run 1 to Run 2 for 3D visualization. Subjective and objective outcomes support the utility of 3D visualization for neuroendoscopic techniques. Visualization that provides real-time, high-resolution binocular depth perception has a role in endoscopic skull base surgery and other neuroendoscopic procedures.


Subject(s)
Neuroendoscopy/methods , Neurosurgical Procedures/instrumentation , Neurosurgical Procedures/methods , Stereotaxic Techniques/instrumentation , Endpoint Determination , Humans , Image Enhancement , Imaging, Three-Dimensional , Skull Base/surgery , Surveys and Questionnaires
17.
J Phys Condens Matter ; 21(41): 415602, 2009 Oct 14.
Article in English | MEDLINE | ID: mdl-21693992

ABSTRACT

We report (11)B and (195)Pt NMR Knight shift K and spin-lattice relaxation rate 1/T(1) in CePt(2)B(2)C in the range 4-315 K. The quadrupolar coupling constant, ν(Q) for boron nuclei is 790 ± 10 kHz. The change of hyperfine field, H(hf), is observed below 30 K in the K versus susceptibility, χ, plot. The calculated value of H(hf) at the (11)B ((195)Pt) is 0.156 (6.86) kOe/µ(B) in the range 30-300 K and ∼0 (0.22) kOe/µ(B) below 30 K. The 1/T(1) versus T curve shows some exotic behavior. The Ce 4f spin contribution to the nuclear relaxation rate (1/T(1f)) in each case is obtained by subtracting the T(1K)(-1) estimated from its La analog, i.e. LaPt(2)B(2)C. In the case of (11)B resonance, in the temperature range of 300-100 K, (1/T(1f)) is independent of T, suggesting a Curie-Weiss behavior of the imaginary part of the dynamic susceptibility. It then shows a slow but continuous increment in the range 100-70 K, indicating a signature of the development of short-range magnetic correlation among the Ce 4f spins. Below 70 K, this enhancement of 1/T(1f) is completely suppressed and it decreases sharply, indicating a suppression of the effect of magnetic correlation, due to the dominance of the Kondo effect over the RKKY interaction. 1/T(1f), follows ∼T(α), with an exponent α∼0.7 in the range 4-30 K for (195)Pt and in the range 8-30 K for (11)B resonance. This is a characteristics of a non-Fermi-liquid like behavior. However, in the case of (11)B, there is again a clear change in the slope of the 1/T(1f) versus T curve below 8 K, with the value of α = 1.0, as if the behavior of the conduction electrons approaches towards a Fermi liquid, when probed near the (11)B site.

18.
Minim Invasive Neurosurg ; 51(5): 306-9, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18855298

ABSTRACT

Intrasellar and sellar-suprasellar adenomas are generally removed through a transsphenoidal approach. Giant adenomas with significant suprasellar extension often require a craniotomy or combined "above and below" approach. The use of endoscopes has increased the visualization capacity of the transsphenoidal route and made these surgeries less invasive. In this report, we describe a novel combination of the endoscopic transsphenoidal approach with the endoscopic transventricular approach to remove a giant pituitary macroadenoma extending into the third and lateral ventricles. The tumor was initially removed via an endoscopic transnasal transsphenoidal, transtuberculum, transplanum approach. A second endoscope was then advanced into the lateral ventricle through a pre-coronal burr hole to assist in mobilizing the tumor and assure a complete resection. Multilayer closure and a ventriculo-peritoneal shunt were performed to insure a watertight seal of the skull base. Giant pituitary adenomas have traditionally been removed with staged or combined transsphenoidal and transcranial approaches. We describe the successful implementation of a minimal access endoscopic combined extended transsphenoidal and transventricular approach that avoids craniotomy and brain retraction.


Subject(s)
Craniotomy/methods , Endoscopy/methods , Pituitary Gland/surgery , Pituitary Neoplasms/surgery , Ventriculostomy/methods , Adult , Craniotomy/instrumentation , Humans , Lateral Ventricles/diagnostic imaging , Lateral Ventricles/pathology , Lateral Ventricles/surgery , Magnetic Resonance Imaging , Male , Nasal Cavity/anatomy & histology , Nasal Cavity/surgery , Pituitary Gland/diagnostic imaging , Pituitary Gland/pathology , Pituitary Neoplasms/diagnostic imaging , Pituitary Neoplasms/pathology , Radiography , Sphenoid Bone/anatomy & histology , Sphenoid Bone/surgery , Sphenoid Sinus/pathology , Sphenoid Sinus/surgery , Third Ventricle/diagnostic imaging , Third Ventricle/pathology , Third Ventricle/surgery , Treatment Outcome , Ventriculostomy/instrumentation
19.
Br J Nutr ; 94(3): 437-42, 2005 Sep.
Article in English | MEDLINE | ID: mdl-16176616

ABSTRACT

Anthropometric parameters and catch-up growth were prospectively evaluated in fifty late-diagnosed children with coeliac disease aged 2.25-10 years after 1-4 years of adhering to a strict gluten-free diet (GFD). The anthropometric parameters were expressed as Z scores relative to National Centre for Health Statistics standards using Epi Info 2000 (weight-for-height Z score (WHZ) and height-for-age Z score (HAZ)). Catch-up growth was evaluated by repeated measures. ANOVA, overall significance by an F test and pair-wise comparisons for estimated marginal means using the least significant difference. At the time of enrolment, no significant difference was observed in WHZ and HAZ between children diagnosed before (group 1) or after (group 2) 4 years of age. On follow-up, HAZ was significantly higher in group 1 after the first and third years of the GFD (P=0.04 and 0.02, respectively), with a non-significant increase after completing 4 years of the GFD (P=0.22). Feeding the GFD resulted in an overall significant (F=3.99, P=0.011) increase in HAZ up to 4 years of follow-up. However, the catch-up in height was incomplete, with stunting in sixteen (55.4%) of twenty-nine children after 3 years and in seven (46.6%) of fifteen children after 4 years on the GFD. Pair-wise comparisons demonstrated a linear catch-up growth during the initial follow-up on GFD. Treatment with the GFD did not result in an overall significant increase in WHZ up to 4 years of follow-up (F=1.01, P=0.42). Our results suggest that, in children with late-diagnosed coeliac disease, treatment with a GFD leads to a normalisation of body mass and a significant but incomplete recovery in HAZ during 4 years of follow-up.


Subject(s)
Celiac Disease/physiopathology , Growth , Analysis of Variance , Anthropometry , Body Mass Index , Celiac Disease/diagnosis , Celiac Disease/diet therapy , Child , Child, Preschool , Female , Follow-Up Studies , Glutens , Humans , Male , Prospective Studies
20.
Indian J Pediatr ; 72(1): 85, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15684460

ABSTRACT

Disseminated cryptococcosis is a rare and often fatal disease in children. The majority of cases usually occur in individuals with defective cell-mediated immunity, most commonly due to HIV infection. The authors here in report an 8-year-old girl from Nepal who presented with fever, cough, headache, lymphadenopathy, hepatosplenomegaly and cutaneous lesions. Lymph node biopsy revealed multiple granulomas composed of histiocytes and epitheliold cells along with numerous yeast forms of cryptococcus. Cultures of CSF, sputum and urine yielded cryptococcus neoformans. Surprisingly,the immune function in terms of T-cell number, CD4 : CD8 ratio, serum immunoglobulins and HIV serology was normal. After the diagnosis of disseminated cryptococcosis was established, the patient was treated with 5-fluorocytosine (100 mg/kg/day) for initial two weeks and amphotericin B (1 mg/kg/day) for 13 weeks. Patient responded well to the treatment with disappearance of presenting symptoms, cutaneous lesions, and lymphadenopathy, though she still had hepatosplenomegaly, which also decreased. Unfortunately, she developed loss of vision in 10th week of therapy. The patient was discharged on oral fluconazole (6 mg/kg/day) and no recurrence was found during the follow-up period of more than 9 months. This is the first case of disseminated cryptococcosis with no detectable immune deficit, from India.


Subject(s)
Antifungal Agents/therapeutic use , Cryptococcosis/diagnosis , Flucytosine/therapeutic use , Child , Cryptococcosis/drug therapy , Cryptococcosis/immunology , Female , Humans , Immunocompetence
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