Left Main Percutaneous Coronary Intervention Versus Coronary Artery Bypass Grafting in Patients With Prior Cerebrovascular Disease: Results From the EXCEL Trial

Objectives

The aim of this study was to determine whether high-risk patients with left main coronary artery disease (LMCAD) and prior cerebrovascular disease (CEVD) preferentially benefit from revascularization by percutaneous coronary intervention (PCI) compared with coronary artery bypass grafting (CABG).

Pre‐discharge and early post‐discharge troponin elevation among patients hospitalized for heart failure with reduced ejection fraction: findings from the ASTRONAUT trial

Aims

Troponin levels are commonly elevated among patients hospitalized for heart failure (HF), but the prevalence and prognostic significance of early post‐discharge troponin elevation are unclear. This study sought to describe the frequency and prognostic value of pre‐discharge and post‐discharge troponin elevation, including persistent troponin elevation from the inpatient to outpatient settings.

Methods and results

The ASTRONAUT trial (NCT00894387; http://www.clinicaltrials.gov ) enrolled hospitalized HF patients with ejection fraction ≤40% and measured troponin I prior to discharge (i.e. study baseline) and at 1‐month follow‐up in a core laboratory (elevation defined as >0.04 ng/mL). This analysis included 1469 (91.0%) patients with pre‐discharge troponin data. Overall, 41.5% and 29.9% of patients had elevated pre‐discharge [median: 0.09 ng/mL; interquartile range (IQR): 0.06–0.19 ng/mL] and 1‐month (median: 0.09 ng/mL; IQR: 0.06–0.15 ng/mL) troponin levels, respectively. Among patients with pre‐discharge troponin elevation, 60.4% had persistent elevation at 1 month. After adjustment, pre‐discharge troponin elevation was not associated with 12‐month clinical outcomes. In contrast, 1‐month troponin elevation was independently predictive of increased all‐cause mortality [hazard ratio (HR) 1.59, 95% confidence interval (CI) 1.18–2.13] and cardiovascular mortality or HF hospitalization (HR 1.28, 95% CI 1.03–1.58) at 12 months. Associations between 1‐month troponin elevation and outcomes were similar among patients with newly elevated (i.e. normal pre‐discharge) and persistently elevated levels (interaction P ≥ 0.16). The prognostic value of 1‐month troponin elevation for 12‐month mortality was driven by a pronounced association among patients with coronary artery disease (interaction P = 0.009).

Conclusions

In this hospitalized HF population, troponin I elevation was common during index hospitalization and at 1‐month follow‐up. Elevated troponin I level at 1 month, but not pre‐discharge, was independently predictive of increased clinical events at 12 months. Early post‐discharge troponin I measurement may offer a practical means of risk stratification and should be investigated as a therapeutic target.

     

Low‐dose anti‐CD20 veltuzumab given intravenously or subcutaneously is active in relapsed immune thrombocytopenia: a phase I study

Low doses of the humanized anti‐CD20 monoclonal antibody, veltuzumab, were evaluated in 41 patients with immune thrombocytopenia (ITP), including 9 with ITP ≤1 year duration previously treated with steroids and/or immunoglobulins, and 32 with ITP >1 year and additional prior therapies. They received two doses of 80–320 mg veltuzumab 2 weeks apart, initially by intravenous (IV) infusion (N = 7), or later by subcutaneous (SC) injections (N = 34), with only one Grade 3 infusion reaction and no other safety issues. Thirty‐eight response‐assessable patients had 21 (55%) objective responses (platelet count ≥30 × 10⁹/l and ≥2 × baseline), including 11 (29%) complete responses (CRs) (platelet count ≥100 × 10⁹/l). Responses (including CRs) occurred with both IV and SC administration, at all veltuzumab dose levels, and regardless of ITP duration. Responders with ITP ≤1 year had a longer median time to relapse (14·4 months) than those with ITP >1 year (5·8 months). Three patients have maintained a response for up to 4·3 years. SC injections resulted in delayed and lower peak serum levels of veltuzumab, but B‐cell depletion occurred after first administration even at the lowest doses. Eight patients, including 6 responders, developed anti‐veltuzumab antibodies following treatment (human anti‐veltuzumab antibody, 19·5%). Low‐dose SC veltuzumab appears convenient, well‐tolerated, and with promising clinical activity in relapsed ITP.( Clinicaltrials.gov identifier: NCT00547066.)     

Interplay between superconductivity and magnetism in Fe1?xPdxTe

The attractive/repulsive relationship between superconductivity and magnetic ordering has fascinated the condensed matter physics community for a century. In the early days, magnetic impurities doped into a superconductor were found to quickly suppress superconductivity. Later, a variety of systems, such as cuprates, heavy fermions, and Fe pnictides, showed superconductivity in a narrow region near the border to antiferromagnetism (AFM) as a function of pressure or doping. However, the coexistence of superconductivity and ferromagnetic (FM) or AFM ordering is found in a few compounds [RRh₄B₄ (R = Nd, Sm, Tm, Er), R′Mo₆X₈ (R′ = Tb, Dy, Er, Ho, and X = S, Se), UMGe (M = Ge, Rh, Co), CeCoIn₅, EuFe₂(As_1−xP_x)₂, etc.], providing evidence for their compatibility. Here, we present a third situation, where superconductivity coexists with FM and near the border of AFM in Fe_1−xPd_xTe. The doping of Pd for Fe gradually suppresses the first-order AFM ordering at temperature T_N/S, and turns into short-range AFM correlation with a characteristic peak in magnetic susceptibility at T′_N. Superconductivity sets in when T′_N reaches zero. However, there is a gigantic ferromagnetic dome imposed in the superconducting-AFM (short-range) cross-over regime. Such a system is ideal for studying the interplay between superconductivity and two types of magnetic (FM and AFM) interactions.Since the first discovery of superconductivity (SC) a century ago, the effects of magnetic impurities and the possibility of magnetic ordering in superconductors has been a central topic of condensed matter physics. Due to strong spin scattering (1, 2), it has generally been believed that the conduction electrons cannot be both magnetically ordered and superconducting. Even though it is thought that Cooper pairs in cuprates, heavy fermions, and Fe-based compounds are mediated by spin fluctuations (3–5), SC generally occurs after suppressing the magnetic ordering either through chemical doping or the application of hydrostatic pressure (6–10). However, there is growing evidence for the coexistence of superconductivity with either ferromagnetic (FM) (11–20) or antiferromagnetic (AFM) ordering (21–24). With the decrease of temperature (T), some of these systems show magnetic ordering before the superconducting transition (T_c) (14–17, 20), some are ordered in a reversed sequence (11–13, 18, 19, 22), some have the two orderings occur concomitantly (22, 25), and some show reentrant superconductivity (partially) overlapping with a magnetically ordered phase (11–13, 26). Despite extensive investigations of interaction between SC and magnetic moments, there is so far no unified theory for the coexistence of SC and magnetism. With the lack of theoretic guidance, the existing experimental findings lead to two schools of thought: one is that both orders result from the same conduction electrons as evidenced by their synchronized magnetic and superconducting orders (22), and the other is that there are two separate sets of electrons responsible for magnetic ordering and superconductivity, respectively (19, 21, 25). What remains incomprehensible is the case where superconductivity and magnetic ordering coexist but are in competition with each other, as seen in Fe-based systems (23, 24, 27).The discovery of superconductivity in Fe-based compounds has sparked enormous interest in the scientific community. Although Fe is the most well known ferromagnet, all parent compounds of Fe-based superconductors exhibit AFM ordering. Though superconductivity is induced after suppressing the AFM ordering, it can coexist with either remaining AFM ordering (23, 24, 27) or new FM ordering (18, 19), and this provides an ideal platform for studying the interplay between superconductivity and magnetism. Among the Fe-based superconductors, the chalcogenide FeTe_1−xSe_x is unique in several aspects: (i) it is the only compound composed of slabs of Fe(Te/Se)₄ stacked together without an interlayer spacer; (ii) it becomes superconducting via isovalent doping of Se for Te, with the highest T_c occurring at the 50% doping level; and (iii) the parent compound Fe_1+yTe shows nonmetallic electrical conduction and forms (π, π)-type AFM ordering with a large magnetic moment (28, 29), in contrast to the (π, 0)-type ordering with a small magnetic moment seen in Fe pnictides. The unusual AFM order in Fe_1+yTe cannot be explained by a simple Fermi-surface nesting picture, thus leading to arguments for a correlated local-moment scenario (27). Because of these differences, the application of hydrostatic pressure or partial doping on the Fe site, such as with Co or Ni, does not generate the generic phase diagram as seen for other Fe-based superconductors (30–33).To gain insight into the relationship between magnetism and superconductivity, we choose to substitute Pd for Fe in FeTe. This decision is motivated by the following: (i) Pd is known to exhibit FM instability (34, 35) even though it is paramagnetic in bulk, and (ii) PdTe is a superconductor with T_c ∼4.5 K (36–42). The partial replacement of Fe by Pd will allow us to understand the roles of Fe, Pd, and Te in both magnetism and superconductivity. Based on electrical transport, and magnetic and thermodynamic property measurements, we show that the ground state of Fe_1−xPd_xTe varies from AFM to FM ordering, to a superconducting state; this is one of rare cases where superconductivity flirts with both AFM and FM.Single crystals of Fe_1−xPd_xTe were grown via high-temperature melting, with the procedure described in SI Text. The crystal structure and the phase purity were measured by both powder and single-crystal X-ray diffraction. Fig. 1 shows powder X-ray diffraction patterns (Fig. 1A) and lattice parameters obtained from single-crystal X-ray refinement (Fig. 1B) for different doping levels; it confirms that the undoped FeTe forms a tetragonal structure, belonging to the P4/nmm space group. At room temperature, the lattice parameters are a = 3.8202 Å and c = 6.2686 Å. Similar to previous observations (43), our single-crystal refinement result indicates that there are ∼9% extra Fe atoms (T2 site of Fig. 1B) incorporated at interstitial sites of the Te layers. As soon as Pd is introduced into the system, the interstitial sites of Fe_1−xPd_xTe are occupied by Pd atoms (i.e., T2 = Pd when x > 0); though it remains in the same tetragonal space group, its lattice parameters a and c both increase with increasing Pd doping concentration for x ≤ x_s ∼0.6 (Fig. 1B). This finding indicates that Pd doping creates negative pressure, which is surprising because Pd²⁺ (∼0.80 Å) has a nearly identical ionic radius as that of Fe²⁺ (∼0.77 Å). The crystal structure of Fe_1−xPd_xTe remains tetragonal up to x_s (∼0.6). Above x_s, Fe_1−xPd_xTe crystallizes in a hexagonal structure (space group P6₃/mmc), and its lattice parameters also increase with increasing x (Fig. 1B); this results in an increase of the unit cell volume with increasing x in the entire doping range (Fig. 1B). In the hexagonal structure, the system no longer incorporates any interstitial sites (Tables S1–S4). Though the hexagonal structure at x > x_s can be regarded as a deformed FeTe structure, the local environment of Fe/Pd is transformed from a tetrahedron (x < x_s) to an octahedron (x > x_s) (44).Open in a separate windowFig. 1.Fe_1−xPd_xTe: (A) Powder X-ray diffraction patterns and (B) its unit cell parameters at room temperature obtained from single-crystal X-ray refinement.To correlate the structural information with physical properties, we show, in Fig. 2, the doping dependence of structural, electrical, and magnetic properties of Fe_1−xPd_xTe, with specifics presented later. The undoped (x = 0) Fe_1.09Te undergoes both an AFM ordering and a structural transition from paramagnetic (PM) tetragonal (high temperatures) to an AFM-ordered monoclinic (low temperatures) phase at T_N/S ∼70 K, with the first-order characteristic. Upon Pd doping, T_N/S is suppressed (solid circles), reaching zero at x = x_N/S ∼0.15 (dash line). In this doping region, the electrical resistivity (ρ) changes from nonmetallic (NM) character (dρ/dT < 0) above T_N/S to metallic (M) behavior (dρ/dT > 0) below T_N/S. When the characteristic feature for the first-order transition is absent at x_N/S, the magnetic susceptibility of Fe_1−xPd_xTe exhibits a peak at T^′_N. The value of T^′_N decreases with increasing x (Fig. 2, open circles), which eventually reaches zero at x_c ∼0.88. The magnetic susceptibility peak is a signature for short-range (SR) AFM correlation developed below T^′_N, with no obvious fingerprint in the electrical resistivity. Above x_c, superconductivity appears (Fig. 2, solid diamonds). The transition temperature T_c increases with increasing x. Remarkably, the system shows ferromagnetism (Fig. 2, solid squares) in the doping range of 0.78 ≤ x ≤ 0.98 with the maximum T_FM (∼190 K) at x_c, where AFM and SC vanish. In addition to the variable magnetic phases, there is doping-induced structural phase transition, being tetragonal at x < x_s ∼0.6 (Fig. 2, dark blue) and hexagonal at x > x_s (light blue). Such a structural transition is responsible for a change of electronic structure, manifested by NM behavior at x < x_s and a metallic character at x > x_s.Open in a separate windowFig. 2.Phase diagram of Fe_1−xPd_xTe. AFM, antiferromagnetic; AFM-M, antiferromagnetically ordered metallic state; FM, ferromagnetically ordered state; M, metallic; NM, nonmetal; PM, paramagnetic; PM-M, paramagnetic metal; SC, superconductivity; SR, short-range; SR-AFM, short-range AFM correlation.We now present the detailed experimental results in support of the phase diagram. Fig. 3A shows the temperature dependence of ρ of Fe_1−xPd_xTe for 0 ≤ x ≤ 0.5 (the experimental technique is described in SI Text). Similar to previous observations (45), the electrical resistivity of undoped (x = 0) Fe_1.09Te increases with decreasing temperature at high temperatures, but sharply decreases below T_N/S ∼70 K; this is caused by the first-order coupled structural and AFM phase transition (45, 46). Below T_N/S, the structure of Fe_1.09Te becomes monoclinic. Upon Pd doping, T_N/S is suppressed, and the first-order transition is no longer observed at x = 0.2. The smooth and monotonic temperature dependence of ρ indicates the absence of both structural and AFM transitions at 0.1 < x < 0.2. Though it sustains a nonmetallic temperature dependence (dρ/dT < 0) down to 2 K, the magnitude of the electrical resistivity deceases with increasing x in the entire doping range above T_N/S (Fig. 3 A and C). For 0.5 < x ≤ 1.0, the electrical resistivity of Fe_1−xPd_xTe continues to decrease with increasing x, as shown in Fig. 3B. More interesting is that ρ shows metallic behavior (dρ/dT > 0) in the entire temperature range measured for 0.5 < x ≤ 1.0. We believe that the cross-over from nonmetallic to metallic character is associated with the structural change at x_s. Furthermore, there is a sharp drop of resistivity at low temperatures for 0.88 < x ≤ 1.0, as shown in Fig. 3D. This drop is due to the emergence of superconductivity because the magnetic susceptibility shows diamagnetism as well in the temperature range (Fig. 3H). Note that the superconducting transition temperature T_c increases with increasing x.Open in a separate windowFig. 3.(A and B) Temperature dependence of the electrical resistivity (ρ) of Pd_1−xFe_xTe at the indicated compositions. (C and D) Temperature dependence of ρ near the first-order AFM/structural transition in the low-doping region, and the superconducting transition in the high-doping region plotted as ρ/ρ(5 K) vs. T, respectively. (E–G) Temperature dependence of the magnetic susceptibility (χ) of Fe_1−xPd_xTe measured at a magnetic field of 1 T. G Inset shows χ vs. x = 0.99 and 1.0; H is the χ(T) measured at 20 oersted (Oe) for 0.97 ≤ x ≤ 1.0.With Pd doping, the magnetic properties of Fe_1−xPd_xTe also change. Fig. 3 E–H shows the temperature dependence of the magnetic susceptibility, χ, at indicated values x. For 0 ≤ x < 0.2, χ initially increases with decreasing temperature, and then drops steeply at T_S/N (Fig. 3E); this confirms the first-order nature of the structural/AFM transition at 0 ≤ x < 0.2. Such a feature is absent for x ≥ x_N/S ∼0.15. Instead, there is a characteristic peak in magnetic susceptibility at T^′_N (Fig. 3F). Because there is no anomaly in electrical resistivity (Fig. 3 A–C) or specific heat, the susceptibility peak cannot be due to a true phase transition, but rather marks the onset of SR AFM correlation as seen in other materials (47). With increasing x, T^′_N moves to lower temperatures, and the magnitude of χ decreases as well (Fig. 3F). Though the characteristic peak is expected to completely vanish around x = x_c ∼0.88, the magnetic susceptibility reveals a dramatic increase below another characteristic temperature T_FM at x ≥ 0.78, as shown in Fig. 3G, which indicates the onset of ferromagnetic ordering at T_FM. With increasing x, T_FM initially increases then decreases after reaching the maximum (∼190 K) at x = x_c ∼0.88. Interestingly, the low-temperature susceptibility peak is still present for samples with x = 0.78, 0.80, 0.83, and 0.88, which suggests the coexistence of FM ordering and AFM interactions in this doping region. Above x_c, χ(T) continues to show FM behavior at high temperatures, but becomes negative at low temperatures (below T_c) under low magnetic fields, as depicted in Fig. 3H. The negative χ below T_c indicates the emergence of superconductivity, because their electrical resistivities also drop sharply (Fig. 3D). Whereas T_FM decreases, T_c increases with increasing x (above x_c). As shown Fig. 3G Inset, χ(T) exhibits paramagnetic behavior above T_c for x = 0.99 and 1.0, indicating the complete suppression of FM. However, T_c continues to increase with x (Fig. 3H).Clearly, there is a coexistence of AFM and FM ordering at 0.78 ≤ x ≤ 0.88, and of FM ordering and SC at 0.88 ≤ x ≤ 0.98 at low temperatures for Fe_1−xPd_xTe, which is further supported by the following results. First, the high-temperature magnetic susceptibility data allows us to extract both Curie–Weiss temperature (θ_CW) and effective magnetic moment (μ_eff) by fitting our experimental data to the Curie–Weiss law , where N_A is the Avogadro’s constant and k_B is Boltzmann’s constant. The x dependences of θ_CW and μ_eff are shown in Fig. 4 A and B, respectively. Note that θ_CW < 0 for x ≤ 0.8, indicating that the dominant magnetic interaction is AFM in this doping region. The fact that | θ_CW | >> T_N/S implies 2D AFM ordering for x < 0.2, whereas a small θ_CW value at 0.2 ≤ x ≤ 0.8 is consistent with our interpretation that there is short-range AFM correlation. And θ_CW > 0 for 0.8 ≤ x < 0.98, which confirms the ferromagnetic interaction in this doping range. Although θ_CW is comparable to the corresponding transition temperature T_FM, the effective magnetic moment is small, as shown in Fig. 4B, which implies that the FM ordering results mainly from Fe, even though Pd has to be the vehicle of coupling between Fe atoms (see discussion below). According to the single-crystal X-ray refinement results (Tables S1–S3), the actual Fe concentration is very close to the nominal value for 0.8 ≤ x ≤ 0.98. We thus estimate the effective magnetic moment of Fe using the nominal Fe concentrations; this gives μ_eff = 1.60μ_B/Fe (x = 0.80), 2.42μ_B/Fe (x = 0.83), 3.79μ_B/Fe (x = 0.88), 4.21μ_B/Fe (x = 0.92), 3.53μ_B/Fe (x = 0.95), and 2.52μ_B/Fe (x = 0.98). Note that the highest magnetic moment for x = 0.92 is close to the Fe moment in Fe_1.09Te (∼ 4.65μ_B/Fe), as plotted in Fig. 4B. In the latter case, the actual ordered magnetic moment is ∼3.31μ_B/Fe (28), smaller than that obtained from the Curie–Weiss constant; this is explained as due to the itinerant nature of the electrons in FeTe (28). For Fe_1−xPd_xTe, we may estimate the ordered magnetic moment from the magnetization. Fig. 4C shows the field dependence (H) of magnetization (M) at T = 3 K for x between 0.80 and 0.98. Note that M(H) reveals a well-defined hysteresis loop, confirming the nature of FM ordering for 0.8 ≤ x ≤ 0.98. Though M(H) is not saturated up to 6 T, we may estimate the lower bound of the ordered magnetic moment using M(H = 6 T) data shown in Fig. 4B. At T = 3 K, μ ∼0.33μ_B/Fe (x = 0.80), 0.48μ_B/Fe (x = 0.83), 1.49μ_B/Fe (x = 0.88), 1.85μ_B/Fe (x = 0.92), 1.67μ_B/Fe (x = 0.95), and 0.22μ_B/Fe (x = 0.98). In addition to the fact that M (H = 6 T) < M_sat, the small ordered magnetic moment could result from (i) the itinerant nature of the electrons and (ii) the reduced concentration of Fe in the highly Pd doped region. Nevertheless, the specific heat reveals anomalies in the compounds with high T_FM (Fig. 4D), indicating a true phase transition at T_FM.Open in a separate windowFig. 4.Fe1-xPdxTe (A) Doping dependence of Curie–Weiss temperature. (B) Doping dependence of the effective magnetic moment and magnetization at 6 T. (C) Magnetization vs. magnetic field at 3 K for x = 0.8, 0.88, 0.92, 0.95, and 0.98. (D) Specific heat vs. temperature for x = 0.92 and 0.88.From the results presented here, it is most likely that the FM dome is intrinsic, due to the ordering of the Fe magnetic moments. Within the dome, our single-crystal X-ray refinement indicates that the structure remains the same as that of pure PdTe with actual Fe concentration close to the nominal value, and there are no interstitial sites of either Pd or Fe, which strongly suggests that the FM ordering is not due to the formation of Fe clusters. In early studies, FM was detected in alloys of Fe in Pd (i.e., Pd_1−xFe_x) at compositions down to 0.08% Fe (48), because magnetic moments on the Fe sites polarize the surrounding Pd matrix (48–51). It seems that Fe doping in PdTe compound gives rise to a similar effect, i.e., Pd matrix mediates the magnetic interactions between Fe atoms.The central question is, how can both FM ordering and superconductivity coexist in the region of 0.88 ≤ x ≤ 0.98? Having excluded the possibility of structural phase separation, one may consider the scenario of electronic phase separation with either macroscopic coexistence of singlet SC and FM in different regions or microscopic coexistence of triplet SC and FM (11, 21, 52). If Fe_1−xPd_xTe were a triplet superconductor, a small amount of impurity or disorder would completely suppress superconductivity, as seen in Sr₂RuO₄ (53). Though we observe anomalous specific heat below T_c of PdTe (42), the insensitivity to Fe doping does not support triplet SC. For the former case, further experimental investigations are necessary, such as combined scanning electron microscopy and tunneling microscopy to directly probe both SC and FM regions. Theoretically, almost all Pd d orbitals in PdTe are occupied due to the covalency of the Pd–Te bonding, according to recent first-principle calculations (44), and this leads to a strong suppression of the local magnetic moment (44). As shown in Fig. 3G (Inset), the magnetic susceptibility of PdTe (x = 1) indeed exhibits paramagnetic behavior above T_c. Upon substitution of Pd by Fe, T_c decreases nearly linearly with increasing Fe concentration (1 − x; Fig. 2). As Fe concentration reaches ∼3% (1 − x = 0.03), both SC and FM ordering coexist. The fact that FM ordering does not immediately kill superconductivity is likely due to the unique electronic structure of PdTe. First-principles calculations indicate that the states in the proximity of the Fermi level consist mainly of Te p electrons, which are weakly hybridized with Pd e_g orbitals (44); this is in dramatic contrast to the electronic structure of FeTe, in which the states near the Fermi level derived from Fe with direct Fe–Fe interactions, and the Te p states lie well below the Fermi level and hybridized weakly with the Fe d states (54). For PdTe, the partial doping of Fe may lead to an even weaker hybridization between Te p and Pd e_g orbitals, due to the shift of Fermi level. Our experimental observation is in support of this scenario: with increasing Fe concentration, superconductivity is gradually suppressed to zero, at which the FM ordering reaches the maximum (Figs. 2 and ​and4).4). After T_c reaches zero at x_c, the disappearance of the superconducting energy gap allows the rearrangement of electronic structure, which is in favor of antiferromagnetic interaction; the latter apparently competes with the existing FM interaction, thus leading to the complete suppression of FM at x < 0.78.In summary, the substitution of Fe by Pd results in an extremely rich phase diagram for Fe_1−xPd_xTe. Powder and single-crystal X-ray diffraction measurements both indicate that there is doping-induced structural transition from a tetragonal phase at x < x_s ∼0.6 to a hexagonal phase at x > x_s. Correspondingly, the electrical resistivity changes from nonmetallic character at x < x_s to metallic behavior at x > x_s. Magnetically, the system undergoes a first-order AFM transition at T_N/S for x ≤ x_N/S ∼0.15, with the structure transition occurring at the same temperature from tetragonal to monoclinic. When T_N/S approaches zero at x_N/S, there is no longer a temperature-induced structural transition, whereas short-range AFM correlation exists for x_N/S < x ≤ 0.88. Superconductivity sets in at x ≥ x_c ∼0.88. In addition, a gigantic FM dome with 0.78 ≤ x ≤ 0.98 is centered at the critical concentration x_c, where both AFM and SC vanish. The coexistence of FM ordering with either SR AFM or SC results most likely from the unique electronic structure of Fe_1−xPd_xTe. With the low Pd concentration, both electrical conduction and magnetism of Fe_1−xPd_xTe are determined by Fe/Pd d electrons, because they are near the Fermi level. Due to the ferromagnetic instability and the extended orbitals of 4d electrons of Pd, both AFM interactions and electrical resistivity in Fe_1−xPd_xTe decrease with increasing x. Before the complete suppression of SR AFM, FM ordering occurs due to the Fe magnetic moment polarization in the Pd matrix. However, the hexagonal structure at x > x_s with Pd/Fe in an octahedral environment leads to more localized d electrons from Pd/Fe but itinerant p electrons from Te. It seems that the weak hybridization between p–d electrons allows for the magnetic ordering of Fe/Pd moments and superconducting ordering of p conduction electrons. Nevertheless, these two orderings compete with each other. Hence, the physics of Fe_1−xPd_xTe in the hexagonal phase is in contrast to known Fe-based superconductors, in which physical properties are mainly determined by Fe d states. Fe_1−xPd_xTe provides another and rare example for studying the interplay between SC, FM, and AFM ordering, where two separate sets of electrons are responsible for FM ordering and superconductivity, respectively.     

Increased arterial stiffness in children on haemodialysis.

BACKGROUND: Measures of aortic stiffness--aortic pulse wave velocity (PWV) and augmentation index (AIx)--have been shown to be powerful predictors of survival in adult haemodialysis (HD) patients. Very few data have been reported regarding arterial stiffness in paediatric renal populations. METHODS: PWV and aortic AIx were determined from contour analysis of arterial waveforms recorded by applanation tonometry using a SphygmoCor device in 14 children on HD (age = 14.1 years) and in 15 age, height matched children controls. RESULTS: Pre-HD AIx (29.7 +/- 15.4%) and PWV (6.6 +/- 1.0 m/s) were significantly higher compared with children controls (8.3 +/- 8.0% and 5.4 +/- 0.6 m/s, respectively, P < 0.0001). The only significant difference between normal and HD children was BP level: 103/61 vs 114/72 mmHg, P < 0.05. In children of HD patients, a multiple linear regression model including BP, age, height, weight, Ca and P levels as independent variables accounted for 57% of the variability in AIx. Dialysis had no impact on AIx (post-HD: 28.5 +/- 12.7%) or on PWV (post-HD: 6.7 +/- 0.8 m/s). CONCLUSIONS: We show, in this first-ever report of increased arterial stiffness in children on dialysis, that end-stage renal disease is associated with abnormalities in arterial wall elastic properties, comparable with adult levels, even in childhood. Most importantly, the absence of a discernible amelioration with dialysis implies that purely structural and not functional alterations lie behind the increased arterial stiffness.     

Ecotoxicological screening of Kenyan tannery dust using a luminescent-based bacterial biosensor

Ecotoxicological screening of dust sampled throughout a Kenyan tannery was conducted using a luminescence (lux)-based bacterial biosensor for both solid and liquid assays. This was complemented by chemical analysis in an attempt to identify possible causative toxic components. The biosensor results showed a highly significant (p < 0.001) difference in both solid and liquid phase toxicity in samples collected from various identified sampling points in the tannery. A positive correlation was observed between results of the solid and liquid phase techniques, for most of the sampling points indicating that the toxic contaminants were bioavailable both in the solid and liquid state. However, the results generally indicated toxicity associated with liquid phase except certain areas in solid phase such as chemical handling, buffing area and weighing. The most toxic tannery area identified was the weighing area (p < 0.001), showing the lowest bioluminescence for both the solid (0.38 +/- 2.21) and liquid phases (0.01 +/- 0.001). Chromium was the metal present in the highest concentration indicating levels higher than the stipulated regulatory requirement of 0.5 mg Cr/m3 for total Cr (highest Cr concentration was at chemical handling at 209.24 mg l(-1)) in all dust samples. The weighing area had the highest Ni concentration (1.87 mg l(-1)) and the chemical handling area showed the highest Zn concentration (31.9 mg l(-1)). These results raise environmental health concerns, as occupational exposure to dust samples from this site has been shown to give rise to elevated concentrations (above the stipulated levels) of chromium in blood, urine and some body tissues, with inhalation being the main route. Health and Safety Executive (HSE), UK, and American Conference of Governmental Industrial Hygienist (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), USA stipulates an occupational exposure limit of 0.5 mg Cr/m3 (8 h TWA) for total chromium. However, schedule 1 of Controls of substances hazardous to health (COSHH) regulations developed by HSE, indicate 0.05 mg m3 (8 h TWA reference periods) to be the limit for Cr (VI) exposure. The exposure limit for individual (e.g., Cr, Zn, Ni etc.) contaminants (homogeneity) was not exceeded, but potential impact of heterogeneity (multi-element synergistic effect) on toxicity requires application of the precautionary principle.     

Enhanced (hydrodynamic) transport induced by population growth in reaction-diffusion systems with application to population genetics

We consider a system made up of different physical, chemical, or biological species undergoing replication, transformation, and disappearance processes, as well as slow diffusive motion. We show that for systems with net growth the balance between kinetics and the diffusion process may lead to fast, enhanced hydrodynamic transport. Solitary waves in the system, if they exist, stabilize the enhanced transport, leading to constant transport speeds. We apply our theory to the problem of determining the original mutation position from the current geographic distribution of a given mutation. We show that our theory is in good agreement with a simulation study of the mutation problem presented in the literature. It is possible to evaluate migratory trajectories from measured data related to the current distribution of mutations in human populations.