568 research outputs found
NHX-type Na+(K+)/H+ antiporters are required for TGN/EE trafficking and endosomal ion homeostasis in Arabidopsis thaliana
The regulation of ion and pH homeostasis of endomembrane organelles is critical for functional protein trafficking, sorting and modification in eukaryotic cells. pH homeostasis is maintained through the activity of vacuolar H+-ATPases (V-ATPases) pumping protons (H+) into the endomembrane lumen, and counter-action by cation/proton exchangers, such as the NHX family of Na+(K+)/H+ exchangers. In plants, V-ATPase activity at the trans-Golgi network/early endosome (TGN/EE) is important for secretory and endocytic trafficking; however, the role of the endosomal antiporters NHX5 and NHX6 in endomembrane trafficking is unclear. Here we show through genetic, pharmacological and live-cell imaging approaches that double knockout of NHX5 and NHX6 results in the impairment of endosome motility and protein recycling at the TGN/EE, but not in the secretion of integral membrane proteins. Furthermore, we report that nhx5 nhx6 mutants are partially insensitive to osmotic swelling of TGN/EE induced by the monovalent cation ionophore monensin, and to late endosomal swelling by the phosphatidylinositol 3/4-kinase inhibitor wortmannin, demonstrating that NHX5 and NHX6 function to regulate the luminal cation composition of endosomes
Bayesian model-data synthesis with an application to global Glacio-Isostatic Adjustment
We introduce a framework for updating large scale geospatial processes using
a model-data synthesis method based on Bayesian hierarchical modelling. Two
major challenges come from updating large-scale Gaussian process and modelling
non-stationarity. To address the first, we adopt the SPDE approach that uses a
sparse Gaussian Markov random fields (GMRF) approximation to reduce the
computational cost and implement the Bayesian inference by using the INLA
method. For non-stationary global processes, we propose two general models that
accommodate commonly-seen geospatial problems. Finally, we show an example of
updating an estimate of global glacial isostatic adjustment (GIA) using GPS
measurements
Quantum information can be negative
Given an unknown quantum state distributed over two systems, we determine how
much quantum communication is needed to transfer the full state to one system.
This communication measures the "partial information" one system needs
conditioned on it's prior information. It turns out to be given by an extremely
simple formula, the conditional entropy. In the classical case, partial
information must always be positive, but we find that in the quantum world this
physical quantity can be negative. If the partial information is positive, its
sender needs to communicate this number of quantum bits to the receiver; if it
is negative, the sender and receiver instead gain the corresponding potential
for future quantum communication. We introduce a primitive "quantum state
merging" which optimally transfers partial information. We show how it enables
a systematic understanding of quantum network theory, and discuss several
important applications including distributed compression, multiple access
channels and multipartite assisted entanglement distillation (localizable
entanglement). Negative channel capacities also receive a natural
interpretation
Case report: Surgical repair of a large tracheo-esophageal fistula in a patient with post-transplant esophageal lymphoproliferative disorder
Introduction and importance
The management of large malignant tracheo-esophageal fistulas (TEF) is not standardized. Herein, we report a case with a malignant TEF associated with esophageal post-transplant lymphoproliferative disorder (PTLD) for whom we successfully performed a surgical repair. This contributes to the knowledge on how to treat large acquired malignant TEFs.
Case presentation
A 69-year old male presented with a one-week history of fever, productive cough and bilateral coarse crackles. In addition, he described a weight loss of 10 kg during the past three months. The patient's history included a kidney transplantation twenty years ago. Esophagogastroduodenoscopy with a biopsy of the esophagus was performed nine days before. Histopathology showed a PTLD of diffuse large B-cell lymphoma subtype. Subsequent diagnostics revealed a progressive TEF (approx. 2.0 × 1.5 cm) 3.0 cm above the carina. PET-CT scan showed an esophagus with slight tracer uptake in the middle third (approx. 11.5 cm length, SUV max 7.4). After decision against stenting, transthoracic subtotal esophagectomy with closure of the tracheal mouth of the fistula by a pedicled flap was performed. PTLD was treated with prednisone and rituximab. Tumor progression (brain metastasis) led to death 95 days after surgery.
Clinical discussion
The treatment of a malignant TEF is complex and personalized while both the consequences of the esophago-tracheal connection and those of the underlying responsible diagnosis have to be considered concurrently. In this case, we considered surgery as the best treatment option due to a relatively good prognosis of the underlying diagnosis (PTLD) and a large fistula. Esophageal or dual stenting, the treatment of choice for small malignant TEF, would have been associated with a high risk of failure due to the wide trachea, extensively dilated esophagus, proximal location and large diameter of the fistula.
Conclusion
Surgery can be considered for patients with a large acquired malignant TEF and positive long-term prognosis of the underlying diagnosis. Due to the complexity of TEF management, immediate pre-operative multidisciplinary discussion is advised
Quantum state merging and negative information
We consider a quantum state shared between many distant locations, and define
a quantum information processing primitive, state merging, that optimally
merges the state into one location. As announced in [Horodecki, Oppenheim,
Winter, Nature 436, 673 (2005)], the optimal entanglement cost of this task is
the conditional entropy if classical communication is free. Since this quantity
can be negative, and the state merging rate measures partial quantum
information, we find that quantum information can be negative. The classical
communication rate also has a minimum rate: a certain quantum mutual
information. State merging enabled one to solve a number of open problems:
distributed quantum data compression, quantum coding with side information at
the decoder and sender, multi-party entanglement of assistance, and the
capacity of the quantum multiple access channel. It also provides an
operational proof of strong subadditivity. Here, we give precise definitions
and prove these results rigorously.Comment: 23 pages, 3 figure
Link-Level Access Cloud Architecture Design Based on SDN for 5G Networks
The exponential growth of data traffic and connected devices, and the reduction of latency and costs, are considered major challenges for future mobile communication networks. The satisfaction of these challenges motivates revisiting the architecture of these networks. We propose an SDN-based design of a hierarchical architecture for the 5G packet core. In this article we focus on the design of its access cloud with the goal of providing low latency and scalable Ethernet-like support to terminals and MTC devices including mobility management. We examine and address its challenges in terms of network scalability and support for link-level mobility. We propose a link-level architecture that forwards frames from and to edge network elements (AP and routers) with a label that identifies the APs through which the terminal is reachable. An SDN local controller tracks and updates the users' location information at the edge network elements. Additionally, we propose to delegate in SDN local controllers the handling of non-scalable operations, such as broadcast and multicast messages, and network management procedures.This work is partially supported by the Spanish Ministry of Economy and
Competitiveness (project TIN2013-46223-P), and the Granada
Excellence Network of Innovation Laboratories (projects
GENIL-PYR-2014-20 and GENIL-PYR-2014-18)
The Resource Theory of Quantum States Out of Thermal Equilibrium
The ideas of thermodynamics have proved fruitful in the setting of quantum
information theory, in particular the notion that when the allowed
transformations of a system are restricted, certain states of the system become
useful resources with which one can prepare previously inaccessible states. The
theory of entanglement is perhaps the best-known and most well-understood
resource theory in this sense. Here we return to the basic questions of
thermodynamics using the formalism of resource theories developed in quantum
information theory and show that the free energy of thermodynamics emerges
naturally from the resource theory of energy-preserving transformations.
Specifically, the free energy quantifies the amount of useful work which can be
extracted from asymptotically-many copies of a quantum system when using only
reversible energy-preserving transformations and a thermal bath at fixed
temperature. The free energy also quantifies the rate at which resource states
can be reversibly interconverted asymptotically, provided that a sublinear
amount of coherent superposition over energy levels is available, a situation
analogous to the sublinear amount of classical communication required for
entanglement dilution.Comment: 4.5 pages main text, 12 pages appendix; v3: improvements to
presentation of the main resul
A new global GPS dataset for testing and improving modelled GIA uplift rates
We have produced a global dataset of ~4000 GPS vertical velocities that can be used as observational estimates of glacial isostatic adjustment (GIA) uplift rates. GIA is the response of the solid Earth to past ice loading, primarily, since the Last Glacial Maximum, about 20 K yrs BP. Modelling GIA is challenging because of large uncertainties in ice loading history and also the viscosity of the upper and lower mantle. GPS data contain the signature of GIA in their uplift rates but these also contain other sources of vertical land motion (VLM) such as tectonics, human and natural influences on water storage that can mask the underlying GIA signal.
A novel fully-automatic strategy was developed to post-process the GPS time series and to correct for non-GIA artefacts. Before estimating vertical velocities and uncertainties, we detected outliers and jumps and corrected for atmospheric mass loading displacements. We corrected the resulting velocities for the elastic response of the solid Earth to global changes in ice sheets, glaciers, and ocean loading, as well as for changes in the Earth's rotational pole relative to the 20th century average. We then applied a spatial median filter to remove sites where local effects were dominant to leave approximately 4000 GPS sites.
The resulting novel global GPS dataset shows a clean GIA signal at all post-processed stations and is suitable to investigate the behaviour of global GIA forward models. The results are transformed from a frame with its origin in the centre of mass of the total Earth's system (CM) into a frame with its origin in the centre of mass of the solid Earth (CE) before comparison with 13 global GIA forward model solutions, with best fits with Pur-6-VM5 and ICE-6G predictions. The largest discrepancies for all models were identified for Antarctica and Greenland, which may be due to either uncertain mantle rheology, ice loading history/magnitude and/or GPS errors
A new global GPS dataset for testing and improving modelled GIA uplift rates
We have produced a global dataset of ~4000 GPS vertical velocities that can be used as observational estimates of glacial isostatic adjustment (GIA) uplift rates. GIA is the response of the solid Earth to past ice loading, primarily, since the Last Glacial Maximum, about 20 K yrs BP. Modelling GIA is challenging because of large uncertainties in ice loading history and also the viscosity of the upper and lower mantle. GPS data contain the signature of GIA in their uplift rates but these also contain other sources of vertical land motion (VLM) such as tectonics, human and natural influences on water storage that can mask the underlying GIA signal.
A novel fully-automatic strategy was developed to post-process the GPS time series and to correct for non-GIA artefacts. Before estimating vertical velocities and uncertainties, we detected outliers and jumps and corrected for atmospheric mass loading displacements. We corrected the resulting velocities for the elastic response of the solid Earth to global changes in ice sheets, glaciers, and ocean loading, as well as for changes in the Earth's rotational pole relative to the 20th century average. We then applied a spatial median filter to remove sites where local effects were dominant to leave approximately 4000 GPS sites.
The resulting novel global GPS dataset shows a clean GIA signal at all post-processed stations and is suitable to investigate the behaviour of global GIA forward models. The results are transformed from a frame with its origin in the centre of mass of the total Earth's system (CM) into a frame with its origin in the centre of mass of the solid Earth (CE) before comparison with 13 global GIA forward model solutions, with best fits with Pur-6-VM5 and ICE-6G predictions. The largest discrepancies for all models were identified for Antarctica and Greenland, which may be due to either uncertain mantle rheology, ice loading history/magnitude and/or GPS errors
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