80 research outputs found

    Ordered Level Planarity, Geodesic Planarity and Bi-Monotonicity

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    We introduce and study the problem Ordered Level Planarity which asks for a planar drawing of a graph such that vertices are placed at prescribed positions in the plane and such that every edge is realized as a y-monotone curve. This can be interpreted as a variant of Level Planarity in which the vertices on each level appear in a prescribed total order. We establish a complexity dichotomy with respect to both the maximum degree and the level-width, that is, the maximum number of vertices that share a level. Our study of Ordered Level Planarity is motivated by connections to several other graph drawing problems. Geodesic Planarity asks for a planar drawing of a graph such that vertices are placed at prescribed positions in the plane and such that every edge is realized as a polygonal path composed of line segments with two adjacent directions from a given set SS of directions symmetric with respect to the origin. Our results on Ordered Level Planarity imply NPNP-hardness for any SS with S4|S|\ge 4 even if the given graph is a matching. Katz, Krug, Rutter and Wolff claimed that for matchings Manhattan Geodesic Planarity, the case where SS contains precisely the horizontal and vertical directions, can be solved in polynomial time [GD'09]. Our results imply that this is incorrect unless P=NPP=NP. Our reduction extends to settle the complexity of the Bi-Monotonicity problem, which was proposed by Fulek, Pelsmajer, Schaefer and \v{S}tefankovi\v{c}. Ordered Level Planarity turns out to be a special case of T-Level Planarity, Clustered Level Planarity and Constrained Level Planarity. Thus, our results strengthen previous hardness results. In particular, our reduction to Clustered Level Planarity generates instances with only two non-trivial clusters. This answers a question posed by Angelini, Da Lozzo, Di Battista, Frati and Roselli.Comment: Appears in the Proceedings of the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

    Resolving the timescales of magmatic and hydrothermal processes associated with porphyry deposit formation using zircon U–Pb petrochronology

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    Understanding the formation of economically important porphyry Cu–Au deposits requires knowledge of the magmatic-to-hydrothermal processes that act within the much larger magmatic system and the timescales on which they occur. We apply high-precision zircon geochronology (chemical abrasion–isotope dilution–thermal ionisation mass spectrometry; CA–ID–TIMS) and spatially resolved zircon geochemistry (laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) to constrain the magmatic evolution of the underlying magma reservoir at the Pliocene Batu Hijau porphyry Cu–Au deposit. We then use this extensive dataset to assess the accuracy and precision of different U–Pb dating methods of the same zircon crystals. Emplacement of the oldest pre- to syn-ore tonalite (3.736±0.023&thinsp;Ma) and the youngest tonalite porphyry to cross-cut economic Cu–Au mineralisation (3.646±0.022&thinsp;Ma) is determined by the youngest zircon grain from each sample, which constrains the duration of metal precipitation to fewer than 90±32&thinsp;kyr. Overlapping spectra of single zircon crystallisation ages and their trace element distributions from the pre-, syn and post-ore tonalite porphyries reveal protracted zircon crystallisation together with apatite and plagioclase within the same magma reservoir over &gt;300&thinsp;kyr. The presented petrochronological data constrain a protracted early &gt;200&thinsp;kyr interval of melt differentiation and cooling within a large heterogeneous magma reservoir, followed by magma storage in a highly crystalline state and chemical and thermal stability over several tens of thousands of years during which fluid expulsion formed the ore deposit. Irregular trace element systematics suggest magma recharge or underplating during this final short time interval. The comparison of high-precision CA–ID–TIMS results with in situ LA-ICP-MS and a sensitive high-resolution ion microprobe (SHRIMP) U–Pb geochronology data from the same zircon grains allows a comparison of the applicability of each technique as a tool to constrain dates and rates on different geological timescales. All techniques provide accurate dates but with different precision. Highly precise dates derived by the calculation of the weighted mean and standard error of the mean of the zircon dates obtained by in situ techniques can lead to ages of unclear geological significance that are older than the maximum ages of emplacement given by the CA–ID–TIMS ages of the youngest zircons in each sample. This lack of accuracy of the weighted means is due to the protracted nature of zircon crystallisation in upper crustal magma reservoirs, suggesting that standard errors should not be used as a means to describe the uncertainty in those circumstances. We conclude from this and similar published studies that the succession of magma and fluid pulses forming a single porphyry deposit and similarly rapid geological events are too fast to be reliably resolved by in situ U–Pb geochronology and that assessing the tempo of ore formation requires CA–ID–TIMS geochronology.</p

    The Function of Hypoxia-Inducible Factor (HIF) Is Independent of the Endoplasmic Reticulum Protein OS-9

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    The protein “amplified in osteosarcoma-9” (OS-9) has been shown previously to interact with the prolyl hydroxylases PHD2 and PHD3. These enzymes initiate oxygen-dependent degradation of the α-subunit of hypoxia-inducible factor (HIF), a transcription factor that adapts cells to insufficient oxygen supply (hypoxia). A new model has been proposed where OS-9 triggers PHD dependent degradation of HIF-α. It was the aim of our study to define the molecular mode of action of OS-9 in the regulation of PHD and HIF activity. Although initial co-immunoprecipitation experiments confirmed physical interaction between OS-9 and PHD2, neither overexpression nor lentiviral inhibition of OS-9 expression affected HIF regulation. Subcellular localization experiments revealed a distinct reticular staining pattern for OS-9 while PHD2 was mainly localized in the cytoplasm. Further cell fractionation experiments and glycosylation tests indicated that OS-9 is a luminal ER protein. In vivo protein interaction analysis by fluorescence resonance energy transfer (FRET) showed no significant physical interaction of overexpressed PHD2-CFP and OS-9-YFP. We conclude that OS-9 plays no direct functional role in HIF degradation since physical interaction of OS-9 with oxygen sensing HIF prolyl hydroxylases cannot occur in vivo due to their different subcellular localization

    Oxygen-Independent Stabilization of Hypoxia Inducible Factor (HIF)-1 during RSV Infection

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    BACKGROUND: Hypoxia-inducible factor 1 (HIF)-1alpha is a transcription factor that functions as master regulator of mammalian oxygen homeostasis. In addition, recent studies identified a role for HIF-1alpha as transcriptional regulator during inflammation or infection. Based on studies showing that respiratory syncytial virus (RSV) is among the most potent biological stimuli to induce an inflammatory milieu, we hypothesized a role of HIF-1alpha as transcriptional regulator during infections with RSV. METHODOLOGY, PRINCIPAL FINDINGS: We gained first insight from immunohistocemical studies of RSV-infected human pulmonary epithelia that were stained for HIF-1alpha. These studies revealed that RSV-positive cells also stained for HIF-1alpha, suggesting concomitant HIF-activation during RSV infection. Similarly, Western blot analysis confirmed an approximately 8-fold increase in HIF-1alpha protein 24 h after RSV infection. In contrast, HIF-1alpha activation was abolished utilizing UV-treated RSV. Moreover, HIF-alpha-regulated genes (VEGF, CD73, FN-1, COX-2) were induced with RSV infection of wild-type cells. In contrast, HIF-1alpha dependent gene induction was abolished in pulmonary epithelia following siRNA mediated repression of HIF-1alpha. Measurements of the partial pressure of oxygen in the supernatants of RSV infected epithelia or controls revealed no differences in oxygen content, suggesting that HIF-1alpha activation is not caused by RSV associated hypoxia. Finally, studies of RSV pneumonitis in mice confirmed HIF-alpha-activation in a murine in vivo model. CONCLUSIONS/SIGNIFICANCE: Taking together, these studies suggest hypoxia-independent activation of HIF-1alpha during infection with RSV in vitro and in vivo

    Extreme enrichment of Se, Te, PGE and Au in Cu sulfide microdroplets: evidence from LA-ICP-MS analysis of sulfides in the Skaergaard Intrusion, east Greenland

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    The Platinova Reef, in the Skaergaard Intrusion, east Greenland, is an example of a magmatic Cu–PGE–Au sulfide deposit formed in the latter stages of magmatic differentiation. As is characteristic with such deposits, it contains a low volume of sulfide, displays peak metal offsets and is Cu rich but Ni poor. However, even for such deposits, the Platinova Reef contains extremely low volumes of sulfide and the highest Pd and Au tenor sulfides of any magmatic ore deposit. Here, we present the first LA-ICP-MS analyses of sulfide microdroplets from the Platinova Reef, which show that they have the highest Se concentrations (up to 1200 ppm) and lowest S/Se ratios (190–700) of any known magmatic sulfide deposit and have significant Te enrichment. In addition, where sulfide volume increases, there is a change from high Pd-tenor microdroplets trapped in situ to larger, low tenor sulfides. The transition between these two sulfide regimes is marked by sharp peaks in Au, and then Te concentration, followed by a wider peak in Se, which gradually decreases with height. Mineralogical evidence implies that there is no significant post-magmatic hydrothermal S loss and that the metal profiles are essentially a function of magmatic processes. We propose that to generate these extreme precious and semimetal contents, the sulfides must have formed from an anomalously metal-rich package of magma, possibly formed via the dissolution of a previously PGE-enriched sulfide. Other processes such as kinetic diffusion may have also occurred alongside this to produce the ultra-high tenors. The characteristic metal offset pattern observed is largely controlled by partitioning effects, producing offset peaks in the order Pt+Pd>Au>Te>Se>Cu that are entirely consistent with published D values. This study confirms that extreme enrichment in sulfide droplets can occur in closed-system layered intrusions in situ, but this will characteristically form ore deposits that are so low in sulfide that they do not conform to conventional deposit models for Cu–Ni–PGE sulfides which require very high R factors, and settling of sulfide liquids

    Generation of first-order expressions from a broad coverage HPSG grammar

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    This paper describes an application for computing first-order semantic representations of English texts. It is based on a combination of hybrid shallow-deep components arranged within the middleware framework Heart of Gold. The shallowdeep semantic analysis employs Robust Minimal Recursion Semantics (RMRS) as a common semantic underspecification formalism for natural language processing components. In order to compute efficiently first-order representations of the input text, the intermediate RMRS results of the shallow-deep analysis are transformed into the dominance constraints formalism and resolved by the underspecification resolver UTool. First-order expressions can serve as a formal knowledge representation of natural text and thus can be utilized in knowledge engineering or textual reasoning. At the end of this paper, we describe their application for recognizing textual entailment

    Linking the thermal evolution and emplacement history of an upper-crustal pluton to its lower-crustal roots using zircon geochronology and geochemistry (southern Adamello batholith, N. Italy)

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    The Val Fredda igneous complex in the southern Adamello batholith (N. Italy) consists of dioritic to gabbroic sills and dykes that were injected at 6-10km depth into partly crystallized tonalites and granodiorites. High-precision U-Pb age determinations by chemical abrasion-isotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) show very similar dispersion of zircon U-Pb dates over 90-200ka and identical age distributions with a dominant mode at 42.5Ma for six samples ranging in composition from gabbro to granodiorite. The co-variation of the probability density curves of zircon dates from mafic and felsic units suggests that they shared a common thermal history with periods of enhanced and reduced zircon growth, reflecting lowered and increased magma temperatures, respectively. However, trace element compositions, Ti-in-zircon temperatures and Hf isotopic compositions of zircon from mafic lithologies are distinctly different from those in felsic zircon and suggest their crystallization occurred in isotopically and chemically diverse magma batches. These magma batches formed in the lower crust from mingling and mixing of residual melts (derived from fractional crystallization of mainly amphibole from basaltic melt) with crustal partial melts at high temperatures above zircon saturation. Zircons crystallized during incipient cooling of these magmas and were entrained into the ascending melts, which were emplaced and rapidly solidified in the upper crust. The reported age dispersions imply that fractional crystallization and hybridization in the lower-to-middle crust, ascent into the upper crust and solidification did not last for more than 200ka. The small magma volumes and flux also preclude significant zircon crystallization at the upper crustal emplacement level

    Development of an open prospective observational multicentre cohort study to determine the impact of standardization of laparoscopic intraperitoneal onlay mesh repair (IPOM) for incisional hernia on clinical outcome and quality of life (LIPOM-Trial)

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    Background: Incisional hernias are one of the most frequent complications in abdominal surgery. Laparoscopic repair has been widely used since its first description but has not been standardized. A panel of hernia experts with expertise on the subject “incisional hernia” was established to review existing literature and define a standard approach to laparoscopic IPOM-repair for incisional hernia. All involved surgeons agreed to perform further IPOM-repairs of incisional hernia according to the protocol. Methods/design: This article summarizes the development of an open prospective observational multicentre cohort study to analyse the impact of a standardization of laparoscopic IPOM-repair for incisional hernia on clinical outcome and quality of life (health care research study). Discussion: Our literature search found that there is a lack of standardization in the surgical approach to incisional hernia and the use of medical devices. The possibility of different surgical techniques, various meshes and a variety of mesh fixation techniques means that the results on outcome after incisional hernia repair are often not comparable between different studies. We believe there is a need for standardization of the surgical procedure and the use of medical devices in order to make the results more comparable and eliminate confounding factors in interpreting the results of surgical hernia repair. This approach, in our view, will also illustrate the influence of the operative technique on the general quality of surgical treatment of incisional hernias better than a “highly selective” study and will indicate the “reality” of surgical treatment not only in specialist centres. Trial registration: The LIPOM-trial is registered at www.clinicaltrials.gov, with identifier: NCT02089958
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