523 research outputs found

    When do pieces determine the whole? Extreme marginals of a completely positive map

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    We will consider completely positive maps defined on tensor products of von Neumann algebras and taking values in the algebra of bounded operators on a Hilbert space and particularly certain convex subsets of the set of such maps. We show that when one of the marginal maps of such a map is an extreme point, then the marginals uniquely determine the map. We will further prove that when both of the marginals are extreme, then the whole map is extreme. We show that this general result is the common source of several well-known results dealing with, e.g., jointly measurable observables. We also obtain new insight especially in the realm of quantum instruments and their marginal observables and channels. &copy; 2014 World Scientific Publishing Company.</p

    Quantum measurements on finite dimensional systems: relabeling and mixing

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    Quantum measurements are mathematically described by positive operator valued measures (POVMs). Concentrating on finite dimensional systems, we show that one can limit to extremal rank-1 POVMs if two simple procedures of mixing and relabeling are permitted. We demonstrate that any finite outcome POVM can be obtained from extremal rank-1 POVMs with these two procedures. In particular, extremal POVMs with higher rank are just relabelings of extremal rank-1 POVMs and their structure is therefore clarified

    Complete measurements of quantum observables

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    We define a complete measurement of a quantum observable (POVM) as a measurement of the maximally refined version of the POVM. Complete measurements give information from the multiplicities of the measurement outcomes and can be viewed as state preparation procedures. We show that any POVM can be measured completely by using sequential measurements or maximally refinable instruments. Moreover, the ancillary space of a complete measurement can be chosen to be minimal.Comment: Based on talk given in CEQIP 2012 conferenc

    Dictionary Matching with One Gap

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    The dictionary matching with gaps problem is to preprocess a dictionary DD of dd gapped patterns P1,,PdP_1,\ldots,P_d over alphabet Σ\Sigma, where each gapped pattern PiP_i is a sequence of subpatterns separated by bounded sequences of don't cares. Then, given a query text TT of length nn over alphabet Σ\Sigma, the goal is to output all locations in TT in which a pattern PiDP_i\in D, 1id1\leq i\leq d, ends. There is a renewed current interest in the gapped matching problem stemming from cyber security. In this paper we solve the problem where all patterns in the dictionary have one gap with at least α\alpha and at most β\beta don't cares, where α\alpha and β\beta are given parameters. Specifically, we show that the dictionary matching with a single gap problem can be solved in either O(dlogd+D)O(d\log d + |D|) time and O(dlogεd+D)O(d\log^{\varepsilon} d + |D|) space, and query time O(n(βα)loglogdlog2min{d,logD}+occ)O(n(\beta -\alpha )\log\log d \log ^2 \min \{ d, \log |D| \} + occ), where occocc is the number of patterns found, or preprocessing time and space: O(d2+D)O(d^2 + |D|), and query time O(n(βα)+occ)O(n(\beta -\alpha ) + occ), where occocc is the number of patterns found. As far as we know, this is the best solution for this setting of the problem, where many overlaps may exist in the dictionary.Comment: A preliminary version was published at CPM 201

    Role of Pneumococcal NanA Neuraminidase Activity in Peripheral Blood

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    The most frequent form of hemolytic-uremic syndrome (HUS) is associated with infections caused by Shiga-like toxin-producing Enterohaemorrhagic Escherichia coli (STEC). In rarer cases HUS can be triggered by Streptococcus pneumoniae. While production of Shiga-like toxins explains STEC-HUS, the mechanisms of pneumococcal HUS are less well known. S. pneumoniae produces neuraminidases with activity against cell surface sialic acids that are critical for factor H-mediated complement regulation on cells and platelets. The aim of this study was to find out whether S. pneumoniae neuraminidase NanA could trigger complement activation and hemolysis in whole blood. We studied clinical S. pneumoniae isolates and two laboratory strains, a wild-type strain expressing NanA, and a NanA deletion mutant for their ability to remove sialic acids from various human cells and platelets. Red blood cell lysis and activation of complement was measured ex vivo by incubating whole blood with bacterial culture supernatants. We show here that NanA expressing S. pneumoniae strains and isolates are able to remove sialic acids from cells, and platelets. Removal of sialic acids by NanA increased complement activity in whole blood, while absence of NanA blocked complement triggering and hemolytic activity indicating that removal of sialic acids by NanA could potentially trigger pHUS.Peer reviewe

    Fatal Babesiosis in Man, Finland, 2004

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    We report an unusual case of human babesiosis in Finland in a 53-year-old man with no history of splenectomy. He had a rudimentary spleen, coexisting Lyme borreliosis, exceptional dark streaks on his extremities, and subsequent disseminated aspergillosis. He was infected with Babesia divergens, which usually causes bovine babesiosis in Finland

    Fast Indexes for Gapped Pattern Matching

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    We describe indexes for searching large data sets for variable-length-gapped (VLG) patterns. VLG patterns are composed of two or more subpatterns, between each adjacent pair of which is a gap-constraint specifying upper and lower bounds on the distance allowed between subpatterns. VLG patterns have numerous applications in computational biology (motif search), information retrieval (e.g., for language models, snippet generation, machine translation) and capture a useful subclass of the regular expressions commonly used in practice for searching source code. Our best approach provides search speeds several times faster than prior art across a broad range of patterns and texts.Comment: This research is supported by Academy of Finland through grant 319454 and has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Actions H2020-MSCA-RISE-2015 BIRDS GA No. 69094

    Neurofilament Light Regulates Axon Caliber, Synaptic Activity, and Organelle Trafficking in Cultured Human Motor Neurons

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    Neurofilament light (NFL) is one of the proteins forming multimeric neuron-specific intermediate filaments, neurofilaments, which fill the axonal cytoplasm, establish caliber growth, and provide structural support. Dominant missense mutations and recessive nonsense mutations in the neurofilament light gene (NEFL) are among the causes of Charcot–Marie–Tooth (CMT) neuropathy, which affects the peripheral nerves with the longest axons. We previously demonstrated that a neuropathy-causing homozygous nonsense mutation in NEFL led to the absence of NFL in patient-specific neurons. To understand the disease-causing mechanisms, we investigate here the functional effects of NFL loss in human motor neurons differentiated from induced pluripotent stem cells (iPSC). We used genome editing to generate NEFL knockouts and compared them to patient-specific nonsense mutants and isogenic controls. iPSC lacking NFL differentiated efficiently into motor neurons with normal axon growth and regrowth after mechanical axotomy and contained neurofilaments. Electrophysiological analysis revealed that motor neurons without NFL fired spontaneous and evoked action potentials with similar characteristics as controls. However, we found that, in the absence of NFL, human motor neurons 1) had reduced axonal caliber, 2) the amplitude of miniature excitatory postsynaptic currents (mEPSC) was decreased, 3) neurofilament heavy (NFH) levels were reduced and no compensatory increases in other filament subunits were observed, and 4) the movement of mitochondria and to a lesser extent lysosomes was increased. Our findings elaborate the functional roles of NFL in human motor neurons. NFL is not only a structural protein forming neurofilaments and filling the axonal cytoplasm, but our study supports the role of NFL in the regulation of synaptic transmission and organelle trafficking. To rescue the NFL deficiency in the patient-specific nonsense mutant motor neurons, we used three drugs, amlexanox, ataluren (PTC-124), and gentamicin to induce translational read-through or inhibit nonsense-mediated decay. However, the drugs failed to increase the amount of NFL protein to detectable levels and were toxic to iPSC-derived motor neurons

    The Psoriasis Risk Allele HLA-C*06 : 02 Shows Evidence of Association with Chronic or Recurrent Streptococcal Tonsillitis

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    Pharyngeal tonsillitis is one of the most common upper respiratory tract infections, and group A streptococcus is the most important bacterial pathogen causing it. While most patients experience tonsillitis only rarely, a subset of patients suffers from recurrent or chronic tonsillitis or pharyngitis. The predisposing factors for recurring or chronic forms of this disease are not yet fully understood, but genetic predisposition has been suggested. A genetic association study using Illumina's Immunochip single-nucleotide polymorphism (SNP) array was performed to search for new genetic biomarkers in pharyngeal tonsillitis. More than 100,000 SNPs relevant to immune-mediated diseases were analyzed in a cohort of 95 patients subjected to tonsillectomy due to recurrent/chronic tonsillitis and 504 controls. Genetic association between the cases and controls showed strongest association with two peaks in the HLA locus (odds ratio [OR], 3.7 to 4.7; P = 4.9 x 10(-6) to 5.7 x 10(-6)). Further analysis with imputed classical HLA alleles suggested the known psoriasis risk allele HLA-C*06:02 as a risk factor for tonsillitis (P = 4.8 x 10(-4); OR, 2.3). In addition, the imputed HLA haplotype HLA-C*06:02/HLA-B*57:01, a reported risk haplotype in psoriasis, had the strongest risk for tonsillitis (P = 3.2 x 10(-4); OR, 6.5). These findings further support the previously reported link between streptococcal throat infections and psoriasis.Peer reviewe
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