804 research outputs found
Negotiating Agency and Control: Theorizing Human-Machine Communication from a Structurational Perspective
Intelligent technologies have the potential to transform organizations and organizing processes. In particular, they are unique from prior organizational technologies in that they reposition technology as agent rather than a tool or object of use. Scholars studying human-machine communication (HMC) have begun to theorize the dual role played by human and machine agency, but they have focused primarily on the individual level. Drawing on Structuration Theory (Giddens, 1984), we propose a theoretical framework to explain agency in HMC as a process involving the negotiation of control between human and machine agents. This article contributes to HMC scholarship by offering a framework and research agenda to guide future theory-building and research on the use of intelligent technologies in organizational contexts
Resonant Interaction Between a Weak Gravitational Wave and a Microwave Beam in the Double Polarized States Through a Static Magnetic Field
We investigate the resonant interaction to the weak gravitational waves in a
coupling electromagnetic system, which consists of a Gaussian beam with the
double polarized transverse electric modes, a static magnetic field and the
fractal membranes. We find that under the syncroresonance condition a
high-frequency GW (HFGW) of h=10^-30,v_g=3GHz may produce the perturbative
photon flux (PPF) of 2.15*10/s in a surface of 0.01m^2. The PPF can be pumped
out from the background photon fluxes and one might obtain the amplified signal
photon flux of 2.15*10^4s^-1 by cascade fractal membranes. It appears to be
worthwhile to study this effect for the detection of the high-frequency relic
GWs in quintessential inflationary models and the HFGWs expected by possible
laboratory schemes.Comment: 10page
Synthesis of unsymmetrical biphenyls as potent cytotoxic agents
Twenty-six unsymmetrical biphenyls were synthesized and evaluated for cytotoxic activity against DU145, A547, KB and KB-Vin tumor cell lines. Three compounds 27, 35 and 40 showed very potent activity against the HTCL panel with an IC50 value range of 0.04–3.23 µM. In addition, fourteen active compounds were all more potent against the drug-resistant KB-Vin cell line than the parental KB cell line. Preliminary SAR analysis indicated that two bulky substituents on the 2,2′-positions of unsymmetrical biphenyl skeleton are necessary and crucial for in vitro anticancer activity, thus providing a good starting point to develop unsymmetrical biphenyls as novel anticancer agents
The Reproducibility of Lists of Differentially Expressed Genes in Microarray Studies
Reproducibility is a fundamental requirement in scientific experiments and clinical contexts. Recent publications raise concerns about the reliability of microarray technology because of the apparent lack of agreement between lists of differentially expressed genes (DEGs). In this study we demonstrate that (1) such discordance may stem from ranking and selecting DEGs solely by statistical significance (P) derived from widely used simple t-tests; (2) when fold change (FC) is used as the ranking criterion, the lists become much more reproducible, especially when fewer genes are selected; and (3) the instability of short DEG lists based on P cutoffs is an expected mathematical consequence of the high variability of the t-values. We recommend the use of FC ranking plus a non-stringent P cutoff as a baseline practice in order to generate more reproducible DEG lists. The FC criterion enhances reproducibility while the P criterion balances sensitivity and specificity
Cytotoxic calanquinone A from Calanthe arisanensis and its first total synthesis
Calanquinone A (1) was isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Its structure was identified by spectroscopic methods. Compound 1 showed potent cytotoxicity (EC50 < 0.5 µg/mL) against lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KB-VIN) cancer cell lines, and interestingly, showed an improved drug resistance profile compared to paclitaxel. The total synthesis of 1 was also achieved and reported herein
Cytotoxic Phenanthrenequinones and 9,10-Dihydrophenanthrenes from Calanthe arisanensis
Two new phenanthrenequinones, calanquinones B–C (2–3), four new 9,10-dihydrophenanthrenes, calanhydroquinones A–C (4–6), and calanphenanthrene A (7), along with five known compounds (1 and 8–11) were isolated from an EtOAc-soluble extract of Calanthe arisanensis through bioassay-guided fractionation. Their structures were identified from spectroscopic data, and the compounds were tested for in vitro cytotoxic activity against human lung (A549), prostate (PC-3 and DU145), colon (HCT-8), breast (MCF-7), nasopharyngeal (KB), and vincristine-resistant nasopharyngeal (KBVIN) cancer cell lines. Compound 1 showed the highest potency (EC50 < 0.5 μg/mL) against all seven cancer cell lines, with the greatest activity against breast cancer MCF-7 cells (EC50 < 0.02 μg/mL). Generally, except for 7, compounds 2–11 also showed significant cytotoxic activity (EC50 < 4μg/mL) against some cell lines (especially PC-3 and MCF-7) in the panel
Revealing histological and morphological features of female reproductive system in tree shrew (Tupaia belangeri)
The tree shrew has been used as a primate animal model in neuroscience studies but it has only rarely been employed in the study of reproductive systems. This is mainly because we know very little about the histological features of reproductive organs of the tree shrew. In this study, we have systematically analyzed the histology of reproductive organs of tree shrew, in comparison with human organs. The uterus of female tree shrew is uterus biomes unicolis, which is connected with an enveloped ovary through a thin fallopian tube. Histologically, the fallopian tube consists of folded mucosa, muscularis and serosa. Like other mammalian animals, the different developmental stages (primordial, primary, secondary and Graafian follicles) of ovarian follicles including inner oocyte and outer granulosa cells are embedded in the cortex. The luminal endometrium, middle muscular myometrium and serosa constitute the wall of uterus of tree shrew. The uterine endometrium contains simple columnar ciliated cells and goblet cells, and there are rich uterine glands in underlying stroma. Furthermore, these glands of tree shrew are round and smaller during anestrus, and become much longer when they are in estrus. The uterine endometrium in younger animals was less developed when compared to a mature tree shrew. Compared to human uterine endometrium, the histological features of tree shrew are very similar, indicating that it could potentially be good primate animal model for studying the diseases in reproductive system
Mth10b, a Unique Member of the Sac10b Family, Does Not Bind Nucleic Acid
The Sac10b protein family is regarded as a group of nucleic acid-binding proteins that are highly conserved and widely distributed within archaea. All reported members of this family are basic proteins that exist as homodimers in solution and bind to DNA and/or RNA without apparent sequence specificity in vitro. Here, we reported a unique member of the family, Mth10b from Methanobacterium thermoautotrophicum ΔH, whose amino acid sequence shares high homology with other Sac10b family proteins. However, unlike those proteins, Mth10b is an acidic protein; its potential isoelectric point is only 4.56, which is inconsistent with the characteristics of a nucleic acid-binding protein. In this study, Mth10b was expressed in Escherichia coli and purified using a three-column chromatography purification procedure. Biochemical characterization indicated that Mth10b should be similar to typical Sac10b family proteins with respect to its secondary and tertiary structure and in its preferred oligomeric forms. However, an electrophoretic mobility shift analysis (EMSA) showed that neither DNA nor RNA bound to Mth10b in vitro, indicating that either Mth10b likely has a physiological function that is distinct from those of other Sac10b family members or nucleic acid-binding ability may not be a fundamental factor to the actual function of the Sac10b family
Associations between genetic variations in the FURIN gene and hypertension
<p>Abstract</p> <p>Background</p> <p>Hypertension is a complex disease influenced by multiple genetic and environmental factors. The Kazakh ethnic group is characterized by a relatively high prevalence of hypertension. Previous research indicates that the FURIN gene may play a pivotal role in the renin-angiotensin system and maintaining the sodium-electrolyte balance. Because these systems influence blood pressure regulation, we considered FURIN as a candidate gene for hypertension. The purpose of this study was to systematically investigate the association between genetic variations in the FURIN gene and essential hypertension in a Xinjiang Kazakh population.</p> <p>Methods</p> <p>We sequenced all exons and the promoter regions of the FURIN gene in 94 hypertensive individuals to identify genetic variations associated with the disorder. Genotyping was performed using the TaqMan polymerase chain reaction method for four representative common single nucleotide polymorphisms (SNPs, -7315C > T, 1970C > G, 5604C > G, 6262C > T) in 934 Kazakh Chinese people. One SNP (1970C > G) was replicated in 1,219 Uygur Chinese people.</p> <p>Results</p> <p>Nine novel and seven known single nucleotide polymorphisms were identified in the FURIN gene. The results suggest that 1970C > G was associated with a hypertension phenotype in Kazakh Chinese (additive model, <it>P </it>= 0.091; dominant model, <it>P = </it>0.031, allele model, <it>P </it>= 0.030), and after adjustment with logistic regression analysis, ORs were 1.451 (95%CI 1.106-1.905, <it>P </it>= 0.008) and 1.496 (95% 1.103-2.028, <it>P </it>= 0.01) in additive and dominant models, respectively. In addition, the association between 1970C > G and hypertension was replicated in Uygur subjects (additive model, <it>P </it>= 0.042; dominant model, <it>P </it>= 0.102; allele model, <it>P </it>= 0.027) after adjustment in additive and dominant models, ORs were 1.327 (95% 1.07-1.646), <it>P </it>= 0.01 and 1.307 (95%CI 1.015-1.681, <it>P </it>= 0.038), respectively. G allele carriers exhibited significant lower urinary Na<sup>+ </sup>excretion rate than non-carriers in the Kazakh Chinese population (152.45 ± 76.04 uM/min vs 173.33 ± 90.02 uM/min, <it>P </it>= 0.007).</p> <p>Conclusion</p> <p>Our results suggest that the FURIN gene may be a candidate gene involved in human hypertension, and that the G allele of 1970C > G may be a modest risk factor for hypertension in Xinjiang Kazakh and Uygur populations.</p
Deep underground laboratory measurement of C(,)O in the Gamow windows of the - and -processes
The C(,)O reaction is the main neutron source for
the slow-neutron-capture (s-) process in Asymptotic Giant Branch stars and for
the intermediate (i-) process. Direct measurements at astrophysical energies in
above-ground laboratories are hindered by the extremely small cross sections
and vast cosmic-ray induced background. We performed the first consistent
direct measurement in the range of 0.24 MeV to 1.9 MeV using the
accelerators at the China Jinping Underground Laboratory (CJPL) and Sichuan
University. Our measurement covers almost the entire i-process Gamow window in
which the large uncertainty of the previous experiments has been reduced from
60\% down to 15\%, eliminates the large systematic uncertainty in the
extrapolation arising from the inconsistency of existing data sets, and
provides a more reliable reaction rate for the studies of the s- and
i-processes along with the first direct determination of the alpha strength for
the near-threshold state
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