Delay-rate tradeoff for ergodic interference alignment in the Gaussian case

In interference alignment, users sharing a wireless channel are each able to achieve data rates of up to half of the non-interfering channel capacity, no matter the number of users. In an ergodic setting, this is achieved by pairing complementary channel realizations in order to amplify signals and cancel interference. However, this scheme has the possibility for large delays in decoding message symbols. We show that delay can be mitigated by using outputs from potentially more than two channel realizations, although data rate may be reduced. We further demonstrate the tradeoff between rate and delay via a time-sharing strategy. Our analysis considers Gaussian channels; an extension to finite field channels is also possible.Comment: 7 pages, 2 figures, presented at 48th Allerton Conference on Communication Control and Computing, 2010. Includes appendix detailing Markov chain analysi

The adrenal cortex and the kidney

The adrenal cortex regulates renal function in a number of important ways; indeed, normal renal function cannot be understood without recognition of such regulation. Well-recognized examples of such regulation are the control of body fluid tonicity through regulation of urinary solute concentration-a function controlled “primarily” by vasopressin, but secondarily and importantly by the adrenal cortex-and control of body sodium-a function controlled primarily by renal tubular sodium reabsorption but regulated by sodium-retaining steroids.The kidney can regulate adrenal function by changing reabsorption of sodium and secretion of potassium, and also by release of renin. The primary target of such regulation is the secretion of aldosterone, which may be influenced by body fluid volume, potassium ion and angiotensin II.Because of these interrelationships, the pathophysiology of certain disease states may be described as aberrations in feedback loops between adrenal cortex and kidney. In this paper we will consider this “system” in some detail, and attempt to explain four disorders as examples of errors in control.In the form of “primary” aldosteronism resulting from hyperplasia of all adrenal cortical tissue, overproduction of aldosterone persists in the absence of all known stimulatory factors. In renovascular hypertension, angiotensin and aldosterone production may persist despite systemic hypertension. In the non-salt-losing form of the adrenogenital syndrome of congenital adrenal hyperplasia without treatment, failure of feedback inhibition by Cortisol may result in overproduction of adrenocorticotropic hormone (ACTH) which, in turn, may lead to overproduction of progesterone. Progesterone may cause sodium loss and overproduction of renin and aldosterone while blocking their effects. In the syndrome of juxtaglomerular hyperplasia with normal blood pressure, overproduction of renin may result from unresponsiveness of blood vessels leading to a lack of feedback inhibition by pressure rise. Under certain circumstances sodium loss can potentiate both the overproduction and the unresponsiveness. Excessive renin leads to aldosteronism and potassium loss

In situ formation of silk-gelatin hybrid hydrogels for affinity-based growth factor sequestration and release

Silk fibroin (SF) and gelatin are natural polymers suitable for biomedical applications, including controlled protein release. SF offers high mechanical strength and slow enzymatic degradability, whereas gelatin contains bioactive motifs that can provide biomimicry to the resulting scaffolds. Owing to their complementary material properties, SF and gelatin are increasingly being used together to afford hybrid scaffolds with adjustable properties. Here, we report the use of in situ crosslinked SF/gelatin hydrogels as a platform for tunable growth factor sequestration and delivery. We demonstrate that the physical assembly of SF into insoluble networks could be accelerated by sonication even in the presence of gelatin. However, the processing conditions from which to prepare SF aqueous solution (e.g., heating duration and number of processing steps) drastically altered the resulting hydrogel physical properties. Furthermore, the stiffness of SF/gelatin hybrid gels displayed temperature dependency. Specifically, incorporation of gelatin increased gel stiffness at 25 °C but decreases hydrogel mechanical stability at 37 °C. The thermostability of SF/gelatin gels can be restored by using a low concentration of genipin, a naturally derived chemical crosslinker. We also incorporate heparin-conjugated gelatin (GH) into the hydrogels to create a hybrid matrix capable of sequestering growth factors, such as basic fibroblast growth factor (bFGF). Both sonicated SF (SSF) and hybrid SSF-GH gels exhibit moderate bFGF sequestration, but only SSF-GH gels afford slow release of bFGF. On the other hand, genipin-stabilized network exhibited the highest retention and sustained release of bFGF, suggesting the suitability of this particular formulation as a scaffold for tissue engineering applications

Intravenous digital subtraction angiography in the assessment of patients with left to right shunts before and after surgical correction

Pre- and postoperative structural changes and pulmonary to systemic flow (QP/QS) ratios were assessed using digital angiography in 34 patients documented to have a left to right shunt at cardiac catheterization. There were 16 men and 18 women whose ages ranged from 4 months to 60 years. The radiographic single mask mode was used for all digital subtraction angiographic studies with a typical radiographic sequence being 80 to 100 kV, 5 to 10 mA/frame at six frames/s for 15 seconds. Renografin-76 was used as a bolus injection at 0.5 to 1.0 ml/kg via an arm vein in most patients. The level of the left to right shunt and any associated anomalies were noted and compared with results from cardiac catheterization. Digital subtraction angiographic flow curves were generated from the pulmonary arteries, and QP/QS ratios were calculated pre- and postoperatively using the gamma variate fit method and compared with the QP/QS ratio from first pass radionuclide studies.A strong correlation between preoperative digital subtraction angiographically derived QP/QS ratio and radionuclide-derived QP/QS ratio was found, with an r value equal to 0.89, p < 0.0001. Postoperatively, all patients had a QP/QS ratio less than 1.2:1.0 for both digital subtraction angiography and radionuclide studies. The level of left to right shunt was accurately assessed in all patients, and its absence observed postoperatively. Associated anomalies, such as a persistent left superior vena cava, coarctation of the aorta and partial anomalous venous return, were identified in all cases.Intravenous digital subtraction angiography provides accurate quantitative and anatomic data in patients with a left to right shunt, is potentially an important outpatient method to assess adequate surgical correction and may suffice preoperatively to proceed to cardiac surgery without preoperative cardiac catheterization

A single H/ACA small nucleolar RNA mediates tumor suppression downstream of oncogenic RAS.

Small nucleolar RNAs (snoRNAs) are a diverse group of non-coding RNAs that direct chemical modifications at specific residues on other RNA molecules, primarily on ribosomal RNA (rRNA). SnoRNAs are altered in several cancers; however, their role in cell homeostasis as well as in cellular transformation remains poorly explored. Here, we show that specific subsets of snoRNAs are differentially regulated during the earliest cellular response to oncogenic RASG12V expression. We describe a novel function for one H/ACA snoRNA, SNORA24, which guides two pseudouridine modifications within the small ribosomal subunit, in RAS-induced senescence in vivo. We find that in mouse models, loss of Snora24 cooperates with RASG12V to promote the development of liver cancer that closely resembles human steatohepatitic hepatocellular carcinoma (HCC). From a clinical perspective, we further show that human HCCs with low SNORA24 expression display increased lipid content and are associated with poor patient survival. We next asked whether ribosomes lacking SNORA24-guided pseudouridine modifications on 18S rRNA have alterations in their biophysical properties. Single-molecule Fluorescence Resonance Energy Transfer (FRET) analyses revealed that these ribosomes exhibit perturbations in aminoacyl-transfer RNA (aa-tRNA) selection and altered pre-translocation ribosome complex dynamics. Furthermore, we find that HCC cells lacking SNORA24-guided pseudouridine modifications have increased translational miscoding and stop codon readthrough frequencies. These findings highlight a role for specific snoRNAs in safeguarding against oncogenic insult and demonstrate a functional link between H/ACA snoRNAs regulated by RAS and the biophysical properties of ribosomes in cancer

Flexible access to conformationally-locked bicyclic morpholines

A preparatively accessible route to a series of conformationally-locked bicyclic morpholines has been developed. This flexible approach allows for diversification in order for a small array of lead-like scaffolds to be synthesised from readily available key building blocks

Molecular characterization of articular cartilage from young adults with femoroacetabular impingement

BACKGROUND: Femoroacetabular impingement is a frequent cause of hip pain and may lead to secondary osteoarthritis, yet little is known about the molecular events linking mechanical hip impingement and articular cartilage degeneration. The first goal of this study was to quantify the expression of inflammatory cytokine and chemokine, matrix-degrading, and extracellular matrix genes in articular cartilage harvested from control hips and hips with femoroacetabular impingement and end-stage osteoarthritis. The second goal was to analyze the relative expression of these genes in articular cartilage harvested at various stages of osteoarthritis. METHODS: Cartilage samples were obtained from thirty-two hips undergoing hip preservation surgery for femoroacetabular impingement or hip arthroplasty. Three control cartilage samples were also analyzed. Specimens were graded intraoperatively with regard to the severity of cartilage damage, the radiographic osteoarthritis grade was recorded, and quantitative RT-PCR (real-time polymerase chain reaction) was performed to determine relative gene expression. RESULTS: Except for interleukin-1β (IL-1β) and CXCL2, the mRNA (messenger RNA) expression of all other chemokine (IL-8, CXCL1, CXCL3, CXCL6, CCL3, and CCL3L1), matrix-degrading (matrix metalloproteinase [MMP]-13 and ADAMTS-4), and structural matrix (COL2A1 [collagen, type II, alpha] and ACAN [aggregan]) genes was higher overall in cartilage from hips with femoroacetabular impingement compared with hips with osteoarthritis and normal controls. The differences reached significance (p ≤ 0.05) for seven of these ten quantified genes, with CXCL3, CXCL6, and COL2A1 being elevated in the femoroacetabular impingement group compared with only the control group and IL-8, CCL3L1, ADAMTS-4, and ACAN being elevated compared with both the osteoarthritis and control groups. When samples were grouped according to the stage of the degenerative cascade, mRNA expression was relatively higher in one of the two middle stages of femoroacetabular impingement (chondromalacia or cleavage/thinning), with the difference reaching significance for IL-8, CXCL2, CXCL3, CCL3L1, and ACAN. ACAN expression was diminished in hips with osteoarthritis compared with femoroacetabular impingement but elevated compared with the control articular cartilage. CONCLUSIONS: Articular cartilage from the impingement zone of hips with femoroacetabular impingement (and particularly those hips in the cleavage/thinning stage) expressed higher levels of certain inflammatory, anabolic, and catabolic genes, representing a heightened metabolic state. CLINICAL RELEVANCE: The articular cartilage from the impingement zone of hips with femoroacetabular impingement was metabolically hyperactive, supporting the concept that such impingement is a structural precursor to hip osteoarthritis

Differential roles of two homologous cyclin-dependent kinase inhibitor genes in regulating cell cycle and innate immunity in arabidopsis\u3csup\u3e1[OPEN]\u3c/sup\u3e

© 2016 American Society of Plant Biologists. All Rights Reserved. Precise cell-cycle control is critical for plant development and responses to pathogen invasion. Two homologous cyclindependent kinase inhibitor genes, SIAMESE (SIM) and SIM-RELATED 1 (SMR1), were recently shown to regulate Arabidopsis (Arabidopsis thaliana) defense based on phenotypes conferred by a sim smr1 double mutant. However, whether these two genes play differential roles in cell-cycle and defense control is unknown. In this report, we show that while acting synergistically to promote endoreplication, SIM and SMR1 play different roles in affecting the ploidy of trichome and leaf cells, respectively. In addition, we found that the smr1-1 mutant, but not sim-1, was more susceptible to a virulent Pseudomonas syringae strain, and this susceptibility could be rescued by activating salicylic acid (SA)-mediated defense. Consistent with these results, smr1-1 partially suppressed the dwarfism, high SA levels, and cell death phenotypes in acd6-1, a mutant used to gauge the change of defense levels. Thus, SMR1 functions partly through SA in defense control. The differential roles of SIM and SMR1 are due to differences in temporal and spatial expression of these two genes in Arabidopsis tissues and in response to P. syringae infection. In addition, flow-cytometry analysis of plants with altered SA signaling revealed that SA is necessary, but not sufficient, to change cell-cycle progression. We further found that a mutant with three CYCD3 genes disrupted also compromised disease resistance to P. syringae. Together, this study reveals differential roles of two homologous cyclin-dependent kinase inhibitors in regulating cell-cycle progression and innate immunity in Arabidopsis and provides insights into the importance of cell-cycle control during host-pathogen interactions

Accuracy of prospective two-dimensional/Doppler echocardiography in the assessment of reparative surgery

Between January 1987 and January 1989, all 129 patients (aged 11 days to 25 years, median 39 months) undergoing both an echocardiographic examination and cardiac catheterization after reparative surgery were prospectively included in a study to assess the accuracy of combined two-dimensional and Doppler color flow imaging. The patient diagnoses were transposition of the great arteries (n = 20), tetralogy of Fallot (n = 38), coarctation of the aorta (n = 24), complete atrioventricular (AV) canal (n = 15), atrial septal defect (n = 8), ventricular septal defects (n = 3), pulmonary stenosis (n = 4), aortic stenosis (n = 8) and subaortic stenosis (n = 9).In arterial tract stenosis, there was high correlation between Doppler estimates and catheterization-derived measurements of residual right ventricular outflow tract obstruction in patients after the arterial switch operation for transposition of the great arteries (r = 0.95) as well as in patients after corrective repair of tetralogy of Fallot (r = 0.84).In semilunar/AV valve regurgitation, graded as none, mild, moderate or severe, echocardiographic estimates correlated exactly with angiographic grading in 84% and differed by one angiographic grade in the other 16%.In residual left to right shunting, no hemodynamically significant shunt was missed by echocardiography. For residual shunts at the ventricular level (n = 32), addition of Doppler color flow imaging improved the sensitivity (from 63% to 94%) and the negative predictive value (from 88% to 98%).In elevated right ventricular pressure, Doppler-derived right ventricular-right atrial pressure estimates in 24 patients correlated well with catheterization measurements (r = 0.93).Combined two-dimensional and Doppler color flow echocardiography was highly accurate in the prospective evaluation of these four types of postoperative residua