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We report $^{51}\mathrm{V}$ NMR and inelastic neutron scattering (INS) measurements on a quasi-1D antiferromagnet ${\mathrm{BaCo}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$ under transverse field along the [010] direction. The scaling behavior of the spin-lattice relaxation rate above the N\'eel temperatures unveils a 1D quantum critical point (QCP) at ${H}_{c}^{1\mathrm{D}}\ensuremath{\approx}4.7\text{ }\text{ }\mathrm{T}$, which is masked by the 3D magnetic order. With the aid of accurate analytical analysis and numerical calculations, we show that the zone center INS spectrum at ${H}_{c}^{1\mathrm{D}}$ is precisely described by the pattern of the 1D quantum Ising model in a magnetic field, a class of universality described in terms of the exceptional ${E}_{8}$ Lie algebra. These excitations are nondiffusive over a certain field range when the system is away from the 1D QCP. Our results provide an unambiguous experimental realization of the massive ${E}_{8}$ phase in the compound, and open a new experimental route for exploring the dynamics of quantum integrable systems as well as physics beyond integrability.

We present a model compound with a spin-1/2 spatially anisotropic frustrated square lattice, in which three antiferromagnetic interactions and one ferromagnetic interaction are competing. We observe an unconventional gradual increase in the low-temperature magnetization curve reminiscent of the quantum critical behavior between gapped and gapless phases. In addition, the specific heat and electron spin resonance signals indicate one-dimensional characteristics. These results demonstrate quantum critical behavior associated with one dimensionalization caused by frustrated interactions in the spin-1/2 spatially anisotropic square lattice., Comment: 6 pages, 4 figures

The magnetic properties of ${\mathrm{Cs}}_{3}{\mathrm{Fe}}_{2}{\mathrm{Cl}}_{9}$ single crystals were investigated by magnetic and thermal measurements. The crystal structure of ${\mathrm{Cs}}_{3}{\mathrm{Fe}}_{2}{\mathrm{Cl}}_{9}$ consists of a bilayer triangular lattice of ${\mathrm{Fe}}^{3+}$ ions. The analysis of magnetic susceptibility clarified that the intra- and interdimer interactions are comparable with each other, and ${\mathrm{Cs}}_{3}{\mathrm{Fe}}_{2}{\mathrm{Cl}}_{9}$ is regarded as a spin-5/2 ${J}_{1}\text{\ensuremath{-}}{J}_{2}$ buckled honeycomb antiferromagnet with the ferromagnetic interlayer interaction ${J}_{3}$. The susceptibility for the magnetic field $H||c$ axis exhibits a sudden drop at the N\'eel temperature ${T}_{\mathrm{N}}=5.4\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, indicating a first-order magnetic phase transition. One of the characteristic features is the linear temperature dependence below ${T}_{\mathrm{N}}$. Furthermore, ${\mathrm{Cs}}_{3}{\mathrm{Fe}}_{2}{\mathrm{Cl}}_{9}$ undergoes successive magnetic phase transitions in high magnetic fields along the $c$ axis. We obtained a rich H-T phase diagram in which the ${M}_{\mathrm{s}}/2$ magnetization-plateau phase is included. These unique magnetic behaviors probably originate from the competition of magnetic interactions and the easy-axis anisotropy in the antiferromagnetic ${J}_{1}\text{\ensuremath{-}}{J}_{2}$ buckled honeycomb network.

Effects of disease progression on healthcare resource utilization (HRU) and costs among multiple myeloma (MM) patients with ≥1 line of therapy (LOT) who received their first stem cell transplant (SCT) within 1 year of initial MM diagnosis were estimated using a large US claims database. Disease progression was defined as advancement to the next LOT, bone metastasis, hypercalcemia, soft tissue plasmacytoma, skeletal related events, acute kidney disease, or death within 12 months of LOT initiation. Annual HRU and costs in the first three LOTs (L1–L3) were compared for patients with versus without disease progression using inverse probability of treatment weighting to adjust for differences between groups in baseline characteristics. In all LOTs, mean annual hospitalizations and healthcare costs were greater for patients with versus without progression. Total incremental annual costs among patients with versus without progression in L1–L3 were $18,359, $87,055, and $71,917, respectively, among LOTs initiated between 2006 and 2018. In LOTs initiated between 2013 and 2018, the figures were $46,024, $100,329, and $101,942 in L1–L3, respectively. The economic burden of disease progression is substantial in this population of MM patients who underwent SCT and received systemic anti-myeloma therapy.

Introduction Copeptin, the C-terminal fragment of antidiuretic hormone (ADH), is a biomarker which has been reported to be increased in cardiovascular and cerebrovascular diseases, thus playing a role in predicting their prognosis. Patients with obstructive sleep apnea syndrome (OSA) have been demonstrated to have a high risk for developing these vascular diseases. However, there have been no authentic reports concerning the effect of continuous positive airway pressure (CPAP) on serum copeptin levels in OSA patients. Purpose We hypothesis that CPAP treatment substantially modifies copeptin levels in OSA patients. Methods A total of 60 OSA patients confirmed by polysomnographic examinations was divided into two groups: a mild-moderate OSA (apnea-hypopnea index: AHI Results Twenty-one patients (age: 54.7±12.4 y, male: 17, NT-proBNP: 45.3±44.2 pg/mL) were diagnosed as having mild-moderate OSA (AHI: 16.5±8.4/h), while 39 patients (age: 57.8±11.4y, male: 29, NT-proBNP: 73.7±87.3 pg/mL) were diagnosed as severe OSA (AHI: 49.5±21.1/h). As a whole, there were no significant differences in copeptin and ADH levels between mild-moderate OSA and severe OSA groups (copeptin: 2.1±1.4 pmol/L vs. 1.9±1.4, ADH: 2.3±2.6 pg/dL vs. 2.0±0.7). In 26 severe OSA patients (age: 55.9±12.9y, male: 23, NT-proBNP: 63.3±85.2 pg/mL), these hormones were again evaluated after CPAP initiation. AHI was significantly improved after CPAP treatment (45.5±20.8/h vs. 5.0±5.0, P Conclusions Serum copeptin levels decreased after CPAP treatment in patients with severe OSA. Copeptin, but not ADH, can be considered as a new biomarker for predicting cardio/cerebrovascular events in severe OSA patients. Figure 1 Funding Acknowledgement Type of funding source: None

We report ^{51}V NMR and inelastic neutron scattering (INS) measurements on a quasi-1D antiferromagnet BaCo_{2}V_{2}O_{8} under transverse field along the [010] direction. The scaling behavior of the spin-lattice relaxation rate above the Néel temperatures unveils a 1D quantum critical point (QCP) at H_{c}^{1D}≈4.7 T, which is masked by the 3D magnetic order. With the aid of accurate analytical analysis and numerical calculations, we show that the zone center INS spectrum at H_{c}^{1D} is precisely described by the pattern of the 1D quantum Ising model in a magnetic field, a class of universality described in terms of the exceptional E_{8} Lie algebra. These excitations are nondiffusive over a certain field range when the system is away from the 1D QCP. Our results provide an unambiguous experimental realization of the massive E_{8} phase in the compound, and open a new experimental route for exploring the dynamics of quantum integrable systems as well as physics beyond integrability.

We present studies on the low-energy magnetic excitations in the Lieb-Mattis (LM) ferrimagnetic phase. We investigate the low-energy magnetic excitations in the mixed spin-($\frac{1}{2},\frac{5}{2}$) chain $(4\ensuremath{-}\mathrm{Br}\ensuremath{-}o\ensuremath{-}\mathrm{Me}\mathrm{Py}\ensuremath{-}\mathrm{V})\mathrm{Fe}{\mathrm{Cl}}_{4}$ based on low-temperature specific heat and multifrequency electron spin resonance (ESR) measurements. A clear $\sqrt{T}$ term is observed in the specific heat, which indicates a contribution of the low-energy magnetic excitation with a ferromagnetic quadratic dispersion expected in the LM ferrimagnetic state. Through the ESR mode analysis, we examine the effects of magnetic anisotropy on the excited states in the LM plateau phase.

We present an $S=2$ antiferromagnet composed of a Mn-verdazyl complex $[\mathrm{Mn}{(\mathrm{hfac})}_{2}]\phantom{\rule{0.16em}{0ex}}[o\text{\ensuremath{-}}\mathrm{Py}\text{\ensuremath{-}}\mathrm{V}\text{\ensuremath{-}}{(4\text{\ensuremath{-}}\mathrm{F})}_{2}]$. An analysis of the magnetic behavior reveals that the strong antiferromagnetic intramolecular interaction between spins on ${\mathrm{Mn}}^{2+}$ and the verdazyl radical forms an $S=2$ hybrid spin below approximately 100 K. In the low-temperature regions, the magnetic susceptibility and the specific heat indicate a phase transition to the three-dimensional order of the $S$ = 2 system. Below the transition temperature, the magnetization curve exhibits a metamagnetic phase transition. From the analysis of electron spin resonance modes, we evaluate the on-site biaxial anisotropy responsible for the anisotropic magnetic behavior.

We report experimental and theoretical evidence that Rb$_2$Cu$_2$Mo$_3$O$_{12}$ has a nonmagnetic tetramer ground state of a two-leg ladder comprising antiferromagnetically coupled frustrated spin-$1/2$ chains and exhibits a Haldane spin gap of emergent spin-1 pairs. Three spin excitations split from the spin-1 triplet by a Dzyaloshinskii-Moriya interaction are identified in inelastic neutron-scattering and electron spin resonance spectra. A tiny magnetic field generates ferroelectricity without closing the spin gap, indicating a novel class of ferroelectricity induced by a vector spin chirality order., Comment: main text (6 pages, 5 figures) + supplemental material (10 pages, 8 figures), to appear in Phys. Rev. B (R)

Unconventional features of relativistic Dirac/Weyl quasi-particles in topological materials are most evidently manifested in the 2D quantum Hall effect (QHE), whose variety is further enriched by their spin and/or valley polarization. Although its extension to three dimensions has been long-sought and inspired theoretical proposals, material candidates have been lacking. Here we have discovered valley-contrasting spin-polarized Dirac fermions in a multilayer form in bulk antiferromagnet BaMnSb$_2$, where the out-of-plane Zeeman-type spin splitting is induced by the in-plane inversion symmetry breaking and spin-orbit coupling (SOC) in the distorted Sb square net. Furthermore, we have observed well-defined quantized Hall plateaus together with vanishing interlayer conductivity at low temperatures as a hallmark of the half-integer QHE in a bulk form. The Hall conductance of each layer is found to be nearly quantized to $2(N+1/2)e^2/h$ with $N$ being the Landau index, which is consistent with two spin-polarized Dirac valleys protected by the strong spin-valley coupling., 14 pages, 4 figures. Accepted in Phys. Rev. B (Rapid Communication)

EuCo2Ge2 with the tetragonal structure is a Eu-divalent antiferromagnet with the Neel temperature T N = 23 K. The magnetic easy-axis corresponds to the [100] direction (a-axis), while the [001] direction (c-axis) is a hard-axis. The magnetization for H ∥ [ 100 ] indicates a metamagnetic transition at 25 kOe and saturates above 75 kOe. On the other hand, the hard-axis magnetization increases approximately linearly and saturates above 110 kOe. The magnetic phase diagram was constructed. A characteristic feature in EuCo2Ge2 is known as a valence transition under pressure, from Eu 2 + δ to Eu 3 − δ ′ ( δ , δ ′ 1 ). We also clarified the valence transition by measuring the electrical resistivity under pressure. The valence transition occurs at 3 GPa, with a hysteresis, and terminates at about 4.5 GPa. Further increasing pressure, the electronic state is changed into a moderate heavy fermion state and approaches the nearly trivalent electronic state.

We successfully synthesized a verdazyl-based charge-transfer salt $[o\text{\ensuremath{-}}\mathrm{MePy}\text{\ensuremath{-}}\mathrm{V}\text{\ensuremath{-}}{(p\text{\ensuremath{-}}\mathrm{Br})}_{2}]{\mathrm{FeCl}}_{4}$, which has ${S}_{\mathrm{V}}=1/2$ on the radical $o\text{\ensuremath{-}}\mathrm{MePy}\text{\ensuremath{-}}\mathrm{V}\text{\ensuremath{-}}{(p\text{\ensuremath{-}}\mathrm{Br})}_{2}$ and ${S}_{\mathrm{Fe}}=5/2$ on the ${\mathrm{FeCl}}_{4}$ anion. Ab initio molecular orbital calculations indicate the formation of an ${S}_{\mathrm{V}}=1/2$ honeycomb lattice composed of three types of exchange interaction with two types of inequivalent sites. Further, the ${S}_{\mathrm{V}}=1/2$ at one site is sandwiched by ${S}_{\mathrm{Fe}}=5/2$ spins through antiferromagnetic (AF) interactions. The magnetic properties indicate that the dominant AF interactions between the ${S}_{\mathrm{V}}=1/2$ spins form a gapped singlet state, and the remaining ${S}_{\mathrm{Fe}}=5/2$ spins cause an AF order. The magnetization curve exhibits a linear increase up to approximately 7 T, and an unconventional 5/6 magnetization plateau appears between 7 and 40 T. We discuss the differences between the effective interactions associated with the magnetic properties of the present compound and ($o$-MePy-V)${\mathrm{FeCl}}_{4}$. We explain the low-field linear magnetization curve through a mean-field approximation of an ${S}_{\mathrm{Fe}}=5/2$ spin model. At higher field regions, the 5/6 magnetization plateau and subsequent nonlinear increase are reproduced by the ${S}_{\mathrm{V}}=1/2$ AF dimer, in which a particular internal field is applied to one of the spin sites. The ESR signals in the low-temperature and low-field regime are explained by conventional two-sublattice AF resonance modes with easy-axis anisotropy. These results demonstrate that exchange interactions between ${S}_{\mathrm{V}}=1/2$ and ${S}_{\mathrm{Fe}}=5/2$ spins in $[o\text{\ensuremath{-}}\mathrm{MePy}\text{\ensuremath{-}}\mathrm{V}\text{\ensuremath{-}}{(p\text{\ensuremath{-}}\mathrm{Br})}_{2}]{\mathrm{FeCl}}_{4}$ realize unconventional magnetic properties with low-field classical behavior and field-induced quantum behavior.

We present a new model compound with the $S=1/2$ frustrated square lattice composed of the charge-transfer salt ($o$-MePy-V)${\mathrm{PF}}_{6}$. $Ab\phantom{\rule{4pt}{0ex}}initio$ calculations indicate the formation of an $S=1/2$ square lattice, in which six types of nearest-neighbor ferromagnetic and antiferromagnetic interactions cause frustration. By applying a magnetic field, we observe an unusually gradual increase of magnetization and a subsequent 1/2-plateau-like behavior. A numerical analysis using the tensor network method qualitatively demonstrates such behaviors and suggests a collinear ordered state and a field-enhanced quantum fluctuation. Furthermore, the local magnetization and ${T}_{1}^{\ensuremath{-}1}$ probed by nuclear magnetic resonance measurements support these findings.

International audience; Magnetisation measurements and electron spin resonance (ESR) spectra of a doped quasi two dimensional (2D) antiferromagnet on a triangular lattice Rb1-xKxFe(MoO4)(2) reveal a crucial change of the ground state spin configuration and a disappearance of a characteristic 1/3-magnetisation plateau at x = 0.15. According to theory for triangular antiferromagnets with a weak random modulation of the exchange bonds, this is a result of the competition between the structural and dynamic disorders. The dynamic zero-point or thermal fluctuations are known to lift the degeneracy of the mean field ground state of a triangular antiferromagnet and cause the spin configuration to be the most collinear, while the static disorder provides another selection of the ground state, with the least collinear structure. Low-level doping (x

We present a model compound for the $S=2$ antiferromagnetic (AF) spin chain composed of the salt ($o$-MePy-$\mathrm{V}){\mathrm{FeCl}}_{4}$. Ab initio molecular-orbital calculations indicate the formation of a partially stacked two-dimensional (2D) spin model comprising five types of exchange interactions between $S=1/2$ and $S=5/2$ spins, which locate on verdazyl radical and Fe ion, respectively. The magnetic properties of the synthesized crystals indicate that the dominant interaction between the $S=1/2$ and $S=5/2$ spins stabilizes an $S=2$ spin in the low-temperature region, and an effective $S=2$ AF chain is formed for $T\ensuremath{\ll}10$ K and $Hl4$ T. We explain the magnetization curve and electron-spin-resonance modes quantitatively based on the $S=2$ AF chain. At higher fields above quantitatively 4 T, the magnetization curve assumes two-thirds of the full saturation value for fields between 4 and 20 T, and approaches saturation at $\ensuremath{\sim}40$ T. The spin model in the high-field region can be considered as a quasi-2D $S=1/2$ honeycomb lattice under an effective internal field caused by the fully polarized $S=5/2$ spin.

We have performed electron spin resonance (ESR) measurements in the low temperature magnetic-ordered state of polycrystalline samples of CdYb2S4. This material is one of the rare-earth spinel compounds in which Yb3+ ions form the pyrochlore lattice, and consequently, CdYb2S4 possesses anomalous properties caused by geometrical frustration and anisotropic terms. Some ESR signals have been detected, and their resonance fields are well-fitted by linear lines in the frequency vs. magnetic-field plane. One of the ESR modes appears to intersect the origin of this plane, suggesting a nearly gapless feature in the magnetically ordered state of this material. Two additional ESR modes appear above H c = 2.6 T, indicating that there is a field-induced phase transition at H c. Given the nearly gapless feature of CdYb2S4, we expect that the ground state of CdYb2S4 must be either the Palmer–Chalker state or the ψ 2 state.

${\mathrm{BaCo}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$ consists of Co chains in which a ${\mathrm{Co}}^{2+}$ ion carries a fictitious spin $\frac{1}{2}$ with Ising anisotropy. We performed elastic and inelastic neutron scattering experiments in ${\mathrm{BaCo}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{8}$ in a magnetic field perpendicular to the $c$ axis which is the chain direction. With applying magnetic field along the $a$ axis at 3.5 K, the antiferromagnetic order with the easy axis along the $c$ axis, observed in zero magnetic field, is completely suppressed at 8 T, while the magnetic field gradually induces an antiferromagnetic order with the spin component along the $b$ axis. We also studied magnetic excitations as a function of transverse magnetic field. The lower boundary of the spinon excitations splits gradually with increasing magnetic field. The overall feature of the magnetic excitation spectra in the magnetic field is reproduced by the theoretical calculation based on the spin $\frac{1}{2} XXZ$ antiferromagnetic chain model, which predicts that the dynamic magnetic structure factor of the spin component along the chain direction is enhanced and that along the field direction has clear incommensurate correlations.

We observe a disappearance of the 1/3 magnetization plateau and a striking change of the magnetic configuration under a moderate doping of the model triangular antiferromagnet RbFe(MoO_{4})_{2}. The reason is an effective lifting of degeneracy of mean-field ground states by a random potential of impurities, which compensates, in the low-temperature limit, the fluctuation contribution to free energy. These results provide a direct experimental confirmation of the fluctuation origin of the ground state in a real frustrated system. The change of the ground state to a least collinear configuration reveals an effective positive biquadratic exchange provided by the structural disorder. On heating, doped samples regain the structure of a pure compound, thus allowing for an investigation of the remarkable competition between thermal and structural disorder.

Phonon transport is an essential property of thermoelectric materials. Although the phonon carries heat, which reduces the thermoelectric efficiency, it contributes positively to the Seebeck coefficient S through the phonon-drag effect, as typified by the high-purity semiconductors, which show fairly large S at cryogenic temperatures. Although such a large S is attractive in terms of Peltier cooling, a clear guiding principle for designing thermoelectric materials enriched by the phonon-drag effect remains to be established. Here we demonstrate that a correlated semiconductor, FeSb2, is a promising thermoelectric material featuring quasi-ballistic phonons dragging d electrons with large effective mass. By changing the sample size within the sub-millimetre order for high-purity single crystals, we succeed in substantially increasing S to as much as −27 mV K−1 at low temperatures. Our results exemplify a strategy for exploring phonon-drag-based thermoelectric materials, the performance of which can be maximized by combining heavy electrons with ballistic phonons., Thermoelectric performances depend on phonon and electron transport. Here, Takahashi et al. show that the large Seebeck coefficient observed in high-purity single-crystal FeSb2 is due to the phonon-drag effect and to the high effective mass of d electrons interacting with quasi-ballistic phonons.

For ESR spectroscopy covering sub THz to THz region, we have developed a frequency-step tunable Gyrotron FU II as a radiation source. A pulse magnet is used for high field ESR spectroscopy. The pulse width is around 50 ms. In order to cover this pulse width, the gyrotron can operate during more than 100 ms in pulse length.

We present the first experimental realization of an $S=2$ ferromagnetic-antiferromagnetic (F-AF) alternating chain in a new Mn-verdazyl complex [Mn(hfac)$_2$]$\cdot$($o$-Py-V) [hfac=1,1,1,5,5,5-hexafluoroacetylacetonate; $o$-Py-V=3-(2-pyridyl)-1,5-diphenylverdazyl]. Through the $ab$ $initio$ molecular orbital calculation, magnetization, and ESR measurements, this compound is confirmed to form an $S=2$ F-AF alternating chain with Ising anisotropy below about 100 K. Furthermore, we find an anomalous change in magnetization at 1/4 of the saturation value, which is probably a manifestation of the quantum nature of the system.

We have performed magnetic susceptibility and high-field magnetization measurements on powder samples of Cu(DEP)Br2 (DEP=2,3-diethyl-pyrazine) and Cu(DMP)Cl2 (DMP=2,3-dimethyl-pyrazine) which are regarded as spin-1/2 two-leg spin-ladders in which the exchange constants are given by J ∥ along the leg and J ⊥ along the rung. The temperature dependences of magnetic susceptibilities of these compounds show a round peak at 11 and 18 K, respectively, and are compared with those calculated with a density matrix renormalization group method for α=J ∥/J ⊥=0.45–0.55. The exchange constants of the former and the latter compounds are evaluated to be \(J/k_{\rm B}=16.5~\mathrm{K}\) and \(J/k_{\rm B}=28.4~\mathrm{K}\), respectively. No magnetization at 1.3 K appears in magnetic fields of up to about 5 T for Cu(DEP)Br2 and about 14 T for Cu(DMP)Cl2, and then the magnetization increases monotonically to saturate at around 25 T and 38 T for respective compounds. Both magnetization curves are also compared with those calculated for α=0.45–0.55 using the same exchange parameter values as in the susceptibilities.

We have performed electron spin resonance (ESR) and magnetization measurements on single crystals of K-Fe-jarosite along the a-axis (in the kagome-plane). We have calculated the resonance branches and the magnetization curve using a spin Hamiltonian including the interlayer exchange and the Dzyaloshinsky-Moriya (DM) interactions. By putting the same parameter values for the analyses along the c-axis (normal to the kagome plane), the calculated results show satisfactory agreement with the experimental ones. As a result, we have successfully explained all the experimental results with one set of the intra- and the inter-plane exchange and the DM interaction parameters.

We have investigated the resistive upper critical field (μ 0 H c2) of the iron-based superconductor SrFe2(As1−x P x )2 (x=0.35, T c∼29 K) in pulsed high magnetic fields of up to 52 T. For H∥ab, $\mu_{0}H_{\mathrm{c}2}^{ab}(T)$ exhibits the Werthamer-Helfand-Hohenberg (WHH) like behavior. While, for H∥c, $\mu_{0}H_{\mathrm {c}2}^{c}(T)$ is almost linear against T and exhibits a slightly upward curvature near T c. The anisotropy of μ 0 H c2 decreases from 2.5 near T c to ∼1.2 at T=0 K monotonically. Similar isotropic behavior of μ 0 H c2 at low temperatures has also been observed in the Fe1+δ (Te,Se). We demonstrate the results of the two-band analysis for μ 0 H c2(T) on the present sample and discuss the anisotropy of μ 0 H c2 by comparing with those in some kinds of iron-based superconductors.

BACKGROUND AND PURPOSE: There are few articles characterizing cerebellar lesions in patients with TSC and no published series documenting longitudinal evaluation of these lesions, to our knowledge. Recent suggestion of a correlation between autism and cerebellar lesions in patients with TSC heightens the importance of understanding these lesions. Our purpose was to characterize cerebellar lesions in a cohort of young patients with TSC with specific interest in assessing longitudinal changes. MATERIALS AND METHODS: We retrospectively reviewed MR images from 145 pediatric and young adult patients with tuberous sclerosis (mean age, 7.6 years). A number of imaging characteristics of cerebellar tubers were recorded, and patients were evaluated for SGAs. Patients with follow-up scans >3 months from the original scan were further analyzed for longitudinal tuber characterization. RESULTS: There were 24.1% of patients with focal cerebellar lesions; 52.4% of patients with cerebellar lesions demonstrated change in imaging characteristics during longitudinal analysis. Fifty-one percent of the lesions were enhanced after gadolinium administration. Twenty percent of the patients with cerebellar lesions had pathologically confirmed SGAs compared with the incidence of 11% in the 145 patients with TSC reviewed. CONCLUSIONS: In our large cohort of young patients with TSC, cerebellar tubers were common and 52% of patients had tubers that changed with time. A higher percentage of patients with cerebellar lesions developed SGAs than patients with TSC without cerebellar lesions. Because this is the first reported longitudinal study of cerebellar lesions in TSC, further investigation may provide additional insight into TSC pathology and associated clinical manifestations, such as autism, developmental delay, and seizures.