Resonant Ultrasound Spectroscopy for Irregularly Shaped Samples and Its Application to Uranium Ditelluride.

Resonant ultrasound spectroscopy (RUS) is a powerful technique for measuring the full elastic tensor of a given material in a single experiment. Previously, this technique was practically limited to regularly shaped samples such as rectangular parallelepipeds, spheres, and cylinders [W. M. Visscher et al. J. Acoust. Soc. Am. 90, 2154 (1991)JASMAN0001-496610.1121/1.401643]. We demonstrate a new method for determining the elastic moduli of irregularly shaped samples, extending the applicability of RUS to a much larger set of materials. We apply this new approach to the recently discovered unconventional superconductor UTe_{2} and provide its elastic tensor at both 300 and 4 kelvin.

Magnetoresistance Scaling Reveals Symmetries of the Strongly Correlated Dynamics in BaFe_{2}(As_{1-x}P_{x})_{2}.

The phenomenon of T-linear resistivity commonly observed in a number of strange metals has been widely seen as evidence for the breakdown of the quasiparticle picture of metals. This study shows that a recently discovered H/T scaling relationship in the magnetoresistance of the strange metal BaFe_{2}(As_{1-x}P_{x})_{2} is independent of the relative orientations of current and magnetic field. Rather, its magnitude and form depend only on the orientation of the magnetic field with respect to a single crystallographic axis: the direction perpendicular to the magnetic iron layers. This finding suggests that the magnetotransport scaling does not originate from the conventional averaging or orbital velocity of quasiparticles as they traverse a Fermi surface, but rather from dissipation arising from two-dimensional correlations.

Imaging Anomalous Nematic Order and Strain in Optimally Doped BaFe_{2}(As,P)_{2}.

We present the strain and temperature dependence of an anomalous nematic phase in optimally doped BaFe_{2}(As,P)_{2}. Polarized ultrafast optical measurements reveal broken fourfold rotational symmetry in a temperature range above T_{c} in which bulk probes do not detect a phase transition. Using ultrafast microscopy, we find that the magnitude and sign of this nematicity vary on a 50-100 µm length scale, and the temperature at which it onsets ranges from 40 K near a domain boundary to 60 K deep within a domain. Scanning Laue microdiffraction maps of local strain at room temperature indicate that the nematic order appears most strongly in regions of weak, isotropic strain. These results indicate that nematic order arises in a genuine phase transition rather than by enhancement of local anisotropy by a strong nematic susceptibility. We interpret our results in the context of a proposed surface nematic phase.

Orphan high field superconductivity in non-superconducting uranium ditelluride.

Reentrant superconductivity is an uncommon phenomenon in which the destructive effects of magnetic field on superconductivity are mitigated, allowing a zero-resistance state to survive under conditions that would otherwise destroy it. Typically, the reentrant superconducting region derives from a zero-field parent superconducting phase. Here, we show that in UTe2 crystals extreme applied magnetic fields give rise to an unprecedented high-field superconductor that lacks a zero-field antecedent. This high-field orphan superconductivity exists at angles offset between 29o and 42o from the crystallographic b to c axes with applied fields between 37 T and 52 T. The stability of field-induced orphan superconductivity presented in this work defies both empirical precedent and theoretical explanation and demonstrates that high-field superconductivity can exist in an otherwise non-superconducting material.

Evidence for a delocalization quantum phase transition without symmetry breaking in CeCoIn5.

The study of quantum phase transitions that are not clearly associated with broken symmetry is a major effort in condensed matter physics, particularly in regard to the problem of high-temperature superconductivity, for which such transitions are thought to underlie the mechanism of superconductivity itself. Here we argue that the putative quantum critical point in the prototypical unconventional superconductor CeCoIn5 is characterized by the delocalization of electrons in a transition that connects two Fermi surfaces of different volumes, with no apparent broken symmetry. Drawing on established theory of f-electron metals, we discuss an interpretation for such a transition that involves the fractionalization of spin and charge, a model that effectively describes the anomalous transport behavior we measured for the Hall effect.

Enzyme replacement therapy for mucopolysaccharidoses: opinions of patients and families.

OBJECTIVES: To assess the opinions of individuals with mucopolysaccharidoses (MPS) and their parents regarding the use of enzyme replacement therapy (ERT). STUDY DESIGN: A validated questionnaire, including hypothetical clinical scenarios about ERT for MPS, was distributed to members of MPS support groups in the United States and Australia. RESULTS: The questionnaire was completed by 249 MPS support group members. Overall, 92% were in favor of ERT where MPS causes severe physical problems but does not affect intellect, and 69% were in favor of ERT where the physical limitations are mild and intellect is spared. Only 47% were in favor of ERT where severe physical and intellectual problems are well established; however, 77% were in favor of ERT in this situation if treatment begun early prolongs life and improves quality of life. CONCLUSION: Most respondents were in favor of ERT for MPS, even where it would not alter the intellectual deterioration. The medical community has a responsibility to advocate for their patients in situations where ERT is appropriate and recognize the economic burden and "family function burden" ERT can incur.

A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome.

Multinucleate cellular syncytial formation is a hallmark of skeletal muscle differentiation. Myomaker, encoded by Mymk (Tmem8c), is a well-conserved plasma membrane protein required for myoblast fusion to form multinucleated myotubes in mouse, chick, and zebrafish. Here, we report that autosomal recessive mutations in MYMK (OMIM 615345) cause Carey-Fineman-Ziter syndrome in humans (CFZS; OMIM 254940) by reducing but not eliminating MYMK function. We characterize MYMK-CFZS as a congenital myopathy with marked facial weakness and additional clinical and pathologic features that distinguish it from other congenital neuromuscular syndromes. We show that a heterologous cell fusion assay in vitro and allelic complementation experiments in mymk knockdown and mymkinsT/insT zebrafish in vivo can differentiate between MYMK wild type, hypomorphic and null alleles. Collectively, these data establish that MYMK activity is necessary for normal muscle development and maintenance in humans, and expand the spectrum of congenital myopathies to include cell-cell fusion deficits.

Enzyme replacement therapy and extended newborn screening for mucopolysaccharidoses: opinions of treating physicians.

We conducted a survey of physician opinions in relation to enzyme replacement therapy (ERT) and extended newborn screening (ENBS) for mucopolysaccharidoses (MPS). A questionnaire consisting of hypothetical clinical scenarios about ERT and ENBS for MPS was posted on metab-L, a list server for the metabolic community. The questionnaire included similar questions to those used in previous studies that sought the views of individuals and families affected by MPS. Our aim was to compare medical professionals' opinions with that of the individuals and families affected by MPS that they serve. The questionnaire was completed by 35 physicians, most of whom were metabolic physicians. Responses differed significantly between the physician and parent groups when the clinical scenario involved intellectual impairment. In this setting, physicians were significantly less inclined to advocate the use of ERT. Comparison of the responses to the ENBS scenarios revealed that compared to physicians, family of individuals with MPS were more inclined to desire diagnosis at birth, even if no treatment could alter the outcome of the condition. Compared to the family of individuals with MPS, physicians are more likely to advocate the use of ERT and ENBS where there is proven medical benefit to the affected individual.

De novo mutations of SETBP1 cause Schinzel-Giedion syndrome.

Schinzel-Giedion syndrome is characterized by severe mental retardation, distinctive facial features and multiple congenital malformations; most affected individuals die before the age of ten. We sequenced the exomes of four affected individuals (cases) and found heterozygous de novo variants in SETBP1 in all four. We also identified SETBP1 mutations in eight additional cases using Sanger sequencing. All mutations clustered to a highly conserved 11-bp exonic region, suggesting a dominant-negative or gain-of-function effect.

Fryns-Aftimos syndrome with milder clinical manifestations.

Fryns-Aftimos syndrome (MIM 606155) is a rare condition characterised by pachygyria, severe mental retardation, epilepsy and characteristic facies. We report a patient who, unlike previously reported cases, remains seizure free with relatively mild developmental delay and facial phenotype.

Medial temporal lobe dysgenesis in hypochondroplasia.

We describe two patients who have hypochondroplasia with medial temporal lobe dysgenesis. This association has only been reported once before. Both patients had an FGFR3 mutation: 1620C --> A, resulting in Asn540Lys. FGFR3 is expressed in the brain during development and plays a role in hippocampal formation. We suggest FGFR3 mutations might cause cerebral malformations in hypochondroplasia as well as in thanatophoric dysplasia. Further neuroimaging studies of patients with hypochondroplasia and epilepsy or developmental delay may clarify the proportion of patients with hypochondroplasia who have this pattern of central nervous system abnormalities.

Unilateral acheiria and fatal primary pulmonary hypertension in a girl with incontinentia pigmenti.

We describe a newborn girl with incontinentia pigmenti (IP, MIM308300), unilateral acheiria, and fatal primary pulmonary hypertension. Limb deficiency has not been described previously in IP and pulmonary hypertension only on two previous occasions. A review of the cause of IP shows that these rare manifestations may not be unexpected, given the many roles of the underlying gene product.