TREM2 dependent and independent functions of microglia in Alzheimer\u27s disease

Microglia are central players in brain innate immunity and have been the subject of extensive research in Alzheimer\u27s disease (AD). In this review, we aim to summarize the genetic and functional discoveries that have advanced our understanding of microglia reactivity to AD pathology. Given the heightened AD risk posed by rare variants of the microglial triggering receptor expressed on myeloid cells 2 (TREM2), we will focus on the studies addressing the impact of this receptor on microglia responses to amyloid plaques, tauopathy and demyelination pathologies in mouse and human. Finally, we will discuss the implications of recent discoveries on microglia and TREM2 biology on potential therapeutic strategies for AD

Adult Acute Lymphoid Leukemia Survival in patients receiving treatment with HyperCVAD at the Instituto Nacional de Cancerología (Colombia), January 2001 to June 2005

Introducción: La leucemia linfoide aguda (LLA) en adultos es una enfermedad agresiva y frecuentemente mortal; a pesar del progreso en su tratamiento, la tasa de remisión completa (RC) es del 75%, y la supervivencia libre de enfermedad (SLE) a largo plazo, del 30%. Objetivos: Describir las variables demográficas y desenlaces clínicos de 83 adultos con LLA tratados con el esquema HyperCVAD (HCVAD) en el Instituto Nacional de Cancerología (INC). Materiales y métodos: Se revisaron las historias clínicas de 180 pacientes con leucemias agudas; de éstos, se seleccionaron 83 sujetos mayores de 15 años con diagnóstico de novo de LLA tratada con el esquema HCVAD. Resultados: La media de edad fue 24 años; la mayoría fueron hombres y sólo el 17% tenía más de 50 años; el 74% tuvo inmunofenotipo compatible con LLA de tipo común, el 41% tuvo cariotipo normal y el 8,4% presentó t(9:22). La tasa de RC fue del 61%, y la mortalidad durante la inducción, del 24%. La mediana de supervivencia global (SG) fue 11,3 meses, y la de SLE, 7,34 meses. La toxicidad evaluada durante el inicio de la quimioterapia mostró 92% de neutropenia febril después del primer ciclo y 24% de toxicidad no hematológica. Se encontraron diferencias en la SG y en la SLE respecto de la presencia de la t(9:22), por compromiso en el sistema nervioso central y por leucocitosis.Introduction: Acute lymphoid leukaemia (ALL) is an aggressive disease in adults. In spite of the progress on treatment of haematological neoplasms, adults with ALL have a 75% complete remission rate (CR), and long-term disease-free survival (DFS) no greater than 30%. Objectives: Describe demographic variables and clinical outcomes in 83 adults suffering from ALL treated with HyperCVAD (HCVAD) at the Instituto Nacional de Cancerología (INC) in Bogotá, Colombia. Materials and methods: Clinical histories of 180 patients suffering from acute leukaemia were reviewed; 83 of them were selected who fulfilled the study’s inclusion criteria: being aged more than 15 and having been diagnosed as suffering from ALL treated under the HCVAD scheme. Results: The age of patients participating in the study ranged from 15 to 65 (average 24); most were male and only 17% being older than 50. 74% had common ALL-compatible immuno-phenotype, 41% presented a normal karyotype and 8.4% had t(9:22). The complete remission rate was 61% and the mortality found during induction was 24%. Mean overall survival (OS) was 11.3 months and DFS was 7.34 months. Toxicity evaluated during the first chemotherapy cycle revealed 92% febrile neutropenia and 24% non-haematological toxicity. Differences were found in OS and DFS regarding the presence of t(9:22), CVS compromise and leukocyte count. Conclusions: The results obtained with INC patients following the HCVAD scheme were not equivalent to those which have been previously reported in the literature

Mortalidad y factores sociales del cáncer de próstata para la gestión de políticas públicas. Veracruz, México

Introducción: las elevadas tasas de mortalidad por cáncer de próstata en Veracruz indican la necesidad de gestionar políticas públicas equitativas para su control. Por ello, es necesario analizar las tendencias de mortalidad y los factores sociales relacionados con la salud de la población.Métodos: cálculo de las tasas de mortalidad a nivel nacional y estatal por edad, y en Veracruz, por regiones económicas; en relación con su grado de rezago social.Resultados: La tasa de mortalidad por cáncer de próstata en Veracruz es mayor que la tasa nacional. Dentro del estado, la región del Papaloapan presentó la mayor mortalidad, y un grado de rezago social medio

Readout of a quantum processor with high dynamic range Josephson parametric amplifiers

We demonstrate a high dynamic range Josephson parametric amplifier (JPA) in which the active nonlinear element is implemented using an array of rf-SQUIDs. The device is matched to the 50 $\Omega$ environment with a Klopfenstein-taper impedance transformer and achieves a bandwidth of 250-300 MHz, with input saturation powers up to -95 dBm at 20 dB gain. A 54-qubit Sycamore processor was used to benchmark these devices, providing a calibration for readout power, an estimate of amplifier added noise, and a platform for comparison against standard impedance matched parametric amplifiers with a single dc-SQUID. We find that the high power rf-SQUID array design has no adverse effect on system noise, readout fidelity, or qubit dephasing, and we estimate an upper bound on amplifier added noise at 1.6 times the quantum limit. Lastly, amplifiers with this design show no degradation in readout fidelity due to gain compression, which can occur in multi-tone multiplexed readout with traditional JPAs.Comment: 9 pages, 8 figure

Measurement-Induced State Transitions in a Superconducting Qubit: Within the Rotating Wave Approximation

Superconducting qubits typically use a dispersive readout scheme, where a resonator is coupled to a qubit such that its frequency is qubit-state dependent. Measurement is performed by driving the resonator, where the transmitted resonator field yields information about the resonator frequency and thus the qubit state. Ideally, we could use arbitrarily strong resonator drives to achieve a target signal-to-noise ratio in the shortest possible time. However, experiments have shown that when the average resonator photon number exceeds a certain threshold, the qubit is excited out of its computational subspace, which we refer to as a measurement-induced state transition. These transitions degrade readout fidelity, and constitute leakage which precludes further operation of the qubit in, for example, error correction. Here we study these transitions using a transmon qubit by experimentally measuring their dependence on qubit frequency, average photon number, and qubit state, in the regime where the resonator frequency is lower than the qubit frequency. We observe signatures of resonant transitions between levels in the coupled qubit-resonator system that exhibit noisy behavior when measured repeatedly in time. We provide a semi-classical model of these transitions based on the rotating wave approximation and use it to predict the onset of state transitions in our experiments. Our results suggest the transmon is excited to levels near the top of its cosine potential following a state transition, where the charge dispersion of higher transmon levels explains the observed noisy behavior of state transitions. Moreover, occupation in these higher energy levels poses a major challenge for fast qubit reset

Overcoming leakage in scalable quantum error correction

Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale.Comment: Main text: 7 pages, 5 figure

Suppressing quantum errors by scaling a surface code logical qubit

Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation.Comment: Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table I

Measurement-induced entanglement and teleportation on a noisy quantum processor

Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time that go beyond established paradigms for characterizing phases, either in or out of equilibrium. On present-day NISQ processors, the experimental realization of this physics is challenging due to noise, hardware limitations, and the stochastic nature of quantum measurement. Here we address each of these experimental challenges and investigate measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping, to avoid mid-circuit measurement and access different manifestations of the underlying phases -- from entanglement scaling to measurement-induced teleportation -- in a unified way. We obtain finite-size signatures of a phase transition with a decoding protocol that correlates the experimental measurement record with classical simulation data. The phases display sharply different sensitivity to noise, which we exploit to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realize measurement-induced physics at scales that are at the limits of current NISQ processors

Non-Abelian braiding of graph vertices in a superconducting processor

Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well developed mathematical description of non-Abelian anyons and numerous theoretical proposals, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of employing the anyons for quantum computation and utilize braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and - through the future inclusion of error correction to achieve topological protection - could open a path toward fault-tolerant quantum computing