Content delivery success in wireless caching helper networks depends mainly on cache-based channel selection diversity and network interference. For given channel fading and network geometry, both ...channel selection diversity and network interference dynamically vary according to what and how the caching helpers cache at their finite storage space. We study probabilistic content placement (or caching placement) to desirably control cache-based channel selection diversity and network interference in a stochastic wireless caching helper network, with sophisticated considerations of wireless fading channels, interactions among multiple users, such as interference and loads at caching helpers, and arbitrary memory size. Using stochastic geometry, we derive optimal caching probabilities in the closed form to maximize the average success probability of content delivery and propose an efficient algorithm to find the solution in a noise-limited network. In an interference-limited network, based on a lower bound of the average success probability of content delivery, we find near-optimal caching probabilities in the closed form to control the channel selection diversity and the network interference. We numerically verify that the proposed content placement is superior to other comparable content placement strategies.
Distributed antenna systems (DAS) have been widely implemented in state-of-the art cellular communication systems to cover dead spots. Recent academic studies have shown that in addition to coverage ...improvements, DAS can also have potential advantages such as reduced power and increased system capacity in a single cell environment. This paper analytically quantifies downlink capacity of multicell DAS for two different transmission strategies: selection diversity (where just one or two of the distributed antennas are used) and blanket transmission (where all antennas in the cell broadcast data). Simple repeaters are a special case of our analysis. A generalized information theoretic analysis is provided to illuminate the fundamental limits of such systems in the cellular context. The results show that DAS reduces other-cell interference in a multicell environment and hence significantly improves capacity (by about 2x), with particularly large improvements for users near cell boundaries. Less obviously, from a communication theory standpoint, it is shown that selection diversity is preferable to blanket transmission in terms of achievable ergodic capacity. For blanket transmission, we show that the optimal transmission strategy is just phase steering due to the per antenna module power constraints in DAS
Multi-antenna transmission and reception (known as MIMO) is widely touted as the key technology for enabling wireless broadband services, whose widespread success will require 10 times higher ...spectral efficiency than current cellular systems, at 10 times lower cost per bit. Spectrally efficient, inexpensive cellular systems are by definition densely populated and interference-limited. But spatial multiplexing MIMO systems- whose principal merit is a supposed dramatic increase in spectral efficiency- lose much of their effectiveness in high levels of interference. This article overviews several approaches to handling interference in multicell MIMO systems. The discussion is applicable to any multi-antenna cellular network, including 802.16e/WiMAX, 3GPP (HSDPA and 3GPP LTE), and 3GPP2 (lxEVDO). We argue that many of the traditional interference management techniques have limited usefulness (or are even counterproductive) when viewed in concert with MIMO. The problem of interference in MIMO systems is too large in scope to be handled with a single technique: in practice a combination of complementary countermeasures will be needed. We overview emerging system-level interference-reducing strategies based on cooperation, which will be important for overcoming interference in future spatial multiplexing cellular systems.
Ginseng (Panax ginseng C.A. Meyer) is one of the most popular medicinal herbs, and the root of this plant contains pharmacologically active components, called ginsenosides. Ginsenosides, a class of ...tetracyclic triterpene saponins, are synthesized from dammarenediol-II after hydroxylation by cytochrome P450 (CYP) and then glycosylation by a glycosyltransferase. Protopanaxadiol synthase, which is a CYP enzyme (CYP716A47) that catalyzes the hydroxylation of dammarenediol-II at the C-12 position to yield protopanaxadiol, was recently characterized. Here, we isolated two additional CYP716A subfamily genes (CYP716A52v2 and CYP716A53v2) and determined that the gene product of CYP716A53v2 is a protopanaxadiol 6-hydroxylase that catalyzes the formation of protopanaxatriol from protopanaxadiol during ginsenoside biosynthesis in P. ginseng. Both CYP716A47 and CYP716A53v2 mRNAs accumulated ubiquitously in all organs of ginseng plants. In contrast, CYP716A52v2 mRNA accumulated only in the rhizome. Methyl jasmonate (MeJA) treatment resulted in the obvious accumulation of CYP716A47 mRNA in adventitious roots. However, neither CYP716A52v2 nor CYP716A53v2 mRNA was affected by MeJA treatment during the entire culture period. The ectopic expression of CYP716A53v2 in recombinant WAT21 yeast resulted in protopanaxatriol production after protopanaxadiol was added to the culture medium. In vitro enzymatic activity assays revealed that CYP716A53v2 catalyzed the oxidation of protopanaxadiol to produce protopanaxatriol. The chemical structures of the protopanaxatriol products were confirmed using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC/APCIMS). Our results indicate that the gene product of CYP716A53v2 is a protopanaxadiol 6-hydroxylase that produces protopanaxatriol from protopanaxadiol, which is an important step in the formation of dammarane-type triterpene aglycones in ginseng saponin biosynthesis.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The capacity and robustness of cellular MIMO systems is very sensitive to other-cell interference which will in practice necessitate network level interference reduction strategies. As an alternative ...to traditional static frequency reuse patterns, this paper investigates intercell scheduling among neighboring base stations. We show analytically that cooperatively scheduled transmission, which is well within the capability of present systems, can achieve an expanded multiuser diversity gain in terms of ergodic capacity as well as almost the same amount of interference reduction as conventional frequency reuse. This capacity gain over conventional frequency reuse is O ( M t square-root of log Ns) for dirty paper coding and O (min (M r , M t ) square-root of log N s) for time division, where N s is the number of cooperating base stations employing opportunistic scheduling in an M t x M r MIMO system. From a theoretical standpoint, an interesting aspect of this analysis comes from an altered view of multiuser diversity in the context of a multi-cell system. Previously, multiuser diversity capacity gain has been known to grow as O(log log K ), from selecting the maximum of K exponentially-distributed powers. Because multicell considerations such as the positions of the users, lognormal shadowing, and pathless affect the multiuser diversity gain, we find instead that the gain is O (square-root of 2logic K ), from selecting the maximum of a compound Iognormal-exponential distribution. Finding the maximum of such a distribution is an additional contribution of the paper.
Multi-user diversity in a spectrum sharing system TAE WON BAN; CHOI, Wan; BANG CHUL JUNG ...
IEEE transactions on wireless communications,
2009-Jan., 2009, 2009-01-00, 20090101, Volume:
8, Issue:
1
Journal Article
Peer reviewed
Open access
We investigate the effects of multi-user diversity in a spectrum sharing system where secondary users restrictively utilize a spectrum licensed to primary users only if interference perceived at ...primary users is regulated below a predetermined level. This interference regulation affects the characteristics of multiuser diversity gains previously known in non-spectrum sharing systems. Our numerical and analytical results show that the multiuser diversity gain in a spectrum sharing system increases differently according to conditions given by the transmit power of secondary users, P, and a predetermined interference temperature, Q - if P is sufficiently larger than Q, the multiuser diversity gain in terms of capacity scales like log 2 (W (N s )) similarly to a previously known scaling law in the non-spectrum sharing systems, where W(middot) and N s denote a Lambert W function and the number of secondary transmitters, respectively. However, the scaling law of multiuser diversity gain becomes log 2 (N s ) as P becomes sufficiently larger such that P Gt QN s .
Abstract
Elastin‐like polypeptides (ELPs) are stimulus‐responsive protein‐based biopolymers, and some ELP block copolymers can assemble into spherical nanoparticles with thermosensitivity. In this ...study, three differently charged‐neutral diblock ELPs with different ratios of (1:8, 1:4, and 1:2) and one neutral ELP were synthesized, and the dependence of their physical properties on ELP concentration, pH, temperature, and salt concentration was investigated. In deionized water, all ELPs showed one‐step transition behavior from soluble single chains below the transition temperature (
T
t
), to macroscopic aggregates above the
T
t
. In NaCl solutions, while neutral ELP still aggregated above the
T
t
, the charged‐neutral diblock ELPs (1:4 and 1:2) formed hydrophobic core micelles by self‐assembly above certain NaCl concentration and would not aggregate due to the repulsive force between the same charged molecules on the surface. The temperature‐triggered self‐assembly behavior of each ELP as a function of block ratio, temperature, and salt concentration was investigated using analytical instruments that included a turbidimeter, dynamic light scattering, and transmission electron microscopy.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Doxorubicin (DOX) is a chemotherapeutic agent that has been reported to cause nephrotoxicity in rodent models and to a lesser degree in cancer patients. Female rodents have been shown to be protected ...against several features of DOX-induced nephrotoxicity. Nevertheless, the underlying mechanisms of this sexual dimorphism are not fully elucidated. Therefore, in the current study, we investigated the sex and time-dependent changes in pathological lesions as well as apoptotic and fibrotic markers in response to acute DOX-induced nephrotoxicity. We also determined the effect of acute DOX treatment on the renal expression of the sexually dimorphic enzyme, soluble epoxide hydrolase (sEH), since inhibition of sEH has been shown to protect against DOX-induced nephrotoxicity. Acute DOX-induced nephrotoxicity was induced by a single intra-peritoneal injection of 20 mg/kg DOX to male and female adult C57Bl/6 mice. The kidneys were isolated 1, 3 and 6 days after DOX administration. Histopathology assessment, gene expression of the apoptotic marker, BAX, protein expression of the fibrotic marker, transforming growth factor-β (TGF-β), and gene and protein expression of sEH were assessed. DOX administration caused more severe pathological lesions as well as higher induction of the apoptotic and fibrotic markers in kidneys of male than in female mice. Intriguingly, DOX inhibited sEH protein expression in kidneys of male mice sacrificed at 3 and 6 days following administration, suggesting that induction of sEH is not necessary for acute DOX-induced nephrotoxicity. However, DOX-induced inhibition of renal sEH in male mice may protect the kidney from further DOX-induced injury in a negative feedback mechanism. We also observed lower constitutive expressions of TGF-β and sEH in the kidney of female mice which may contribute, at least in part, to sexual dimorphism of DOX-induced nephrotoxicity.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The estrogen-related receptor (ERR) family of orphan nuclear receptor is composed of ERRα, ERRβ, and ERRγ, which are known to regulate various isoform-specific functions under normal and ...pathophysiological conditions. Here, we investigate the involvement of ERRs in the pathogenesis of osteoarthritis (OA) in mice. Among ERR family members, ERRγ is markedly upregulated in cartilage from human OA patients and various mouse models of OA. Adenovirus-mediated overexpression of ERRγ in mouse knee joint or transgenic expression of ERRγ in cartilage leads to OA. ERRγ overexpression in chondrocytes directly upregulates matrix metalloproteinase (MMP)-3 and MMP13, which are known to play crucial roles in cartilage destruction in OA. In contrast, genetic ablation of Esrrg or shRNA-mediated downregulation of Esrrg in joint tissues abrogates experimental OA in mice. Our results collectively indicate that ERRγ is a novel catabolic regulator of OA pathogenesis.
Abstract
Background
Polygenic risk score (PRS) analyses have become an integral part of biomedical research, exploited to gain insights into shared aetiology among traits, to control for genomic ...profile in experimental studies, and to strengthen causal inference, among a range of applications. Substantial efforts are now devoted to biobank projects to collect large genetic and phenotypic data, providing unprecedented opportunity for genetic discovery and applications. To process the large-scale data provided by such biobank resources, highly efficient and scalable methods and software are required.
Results
Here we introduce PRSice-2, an efficient and scalable software program for automating and simplifying PRS analyses on large-scale data. PRSice-2 handles both genotyped and imputed data, provides empirical association P-values free from inflation due to overfitting, supports different inheritance models, and can evaluate multiple continuous and binary target traits simultaneously. We demonstrate that PRSice-2 is dramatically faster and more memory-efficient than PRSice-1 and alternative PRS software, LDpred and lassosum, while having comparable predictive power.
Conclusion
PRSice-2's combination of efficiency and power will be increasingly important as data sizes grow and as the applications of PRS become more sophisticated, e.g., when incorporated into high-dimensional or gene set–based analyses. PRSice-2 is written in C++, with an R script for plotting, and is freely available for download from http://PRSice.info.
PDF
