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1 |
Modulation of Frequency Preference in Heterogeneous Populations of Theta-resonant Neurons
مدولاسیون اولویت فرکانس در جمعیت ناهمگن نورون های تتا-رزونانس-2020 Abstract—Neurons from several brain regions resonate in the theta frequency range (4–12 Hz), displaying a higher
voltage response to oscillatory currents at a preferred ‘resonant’ frequency (fR). Subthreshold resonance could
influence spiking and contribute to the selective entrainment of neurons during the network oscillatory activity
that accompanies several cognitive processes. Neurons from different regions display resonance in specific theta
subranges, suggesting a functional specialization. Further experimental work is needed to characterize this diversity
and explore how frequency preference could be dynamically modulated. Theoretical studies have shown that
the fine-tuning of resonance depends in a complex way on a variety of intrinsic factors and input properties, but
their specific influence is difficult to dissect in cells. We performed slice electrophysiology, dynamic clamping
and modelling to assess the differential frequency preference of rat entorhinal stellate neurons, hippocampal
CA1 pyramidal neurons and cortical amygdala neurons, which share a hyperpolarization-activated current (Ih)-
dependent resonance mechanism. We found heterogeneous resonance properties among the different types of
theta-resonant neurons, as well as in each specific group. In all the neurons studied, fR inversely correlated with
the effective input resistance (Rin), a measurable variable that depends on passive and active membrane features.
We showed that resonance can be adjusted by manipulations mimicking naturally occurring processes, as the
incorporation of a virtual constant conductance or cell depolarization, in a way that preserves the fR-Rin relationship.
The modulation of frequency selectivity influences firing by shifting spike frequency and timing, which
could influence neuronal communication in an active network. 2019 IBRO. Published by Elsevier Ltd. All rights
reserved. Key words: theta-frequency resonance | frequency modulation | input resistance | resonant frequency | phase-lag | spike timing |
مقاله انگلیسی |
2 |
Modeling dopaminergic modulation of clustered gamma rhythms
مدل سازی مدولاسیون دوپامینرژیک ریتم گاما خوشه ای-2020 Gamma rhythm (20–100 Hz) plays a key role in numerous cognitive tasks: working mem- ory, sensory processing and in routing of information across neural circuits. In compar- ison with lower frequency oscillations in the brain, gamma-rhythm associated firing of the individual neurons is sparse and the activity is locally distributed in the cortex. Such “weak”gamma rhythm results from synchronous firing of pyramidal neurons in an inter- play with the local inhibitory interneurons in a "pyramidal-interneuron gamma" or PING. Experimental evidence shows that individual pyramidal neurons during such oscillations tend to fire at rates below gamma, with the population showing clear gamma oscillations and synchrony. One possible way to describe such features is that this gamma oscilla- tion is generated within local synchronous neuronal clusters. The number of such syn- chronous clusters defines the overall coherence of the rhythm and its spatial structure. The number of clusters in turn depends on the properties of the synaptic coupling and the intrinsic properties of the constituent neurons. We previously showed that a slow spike frequency adaptation current in the pyramidal neurons can effectively control cluster numbers. These slow adaptation currents are modulated by endogenous brain neuromod- ulators such as dopamine, whose level is in turn related to cognitive task requirements. Hence we postulate that dopaminergic modulation can effectively control the clustering of weak gamma and its coherence. In this paper we study how dopaminergic modulation of the network and cell properties impacts the cluster formation process in a PING network model. Keywords: Gamma oscillations | Spike frequency adaptation | Cluster syncronization | Dopamine modulation | Multiple timer scales |
مقاله انگلیسی |
3 |
Modulation of Coordinated Activity across Cortical Layers by Plasticity of Inhibitory Synapses
مدولاسیون فعالیت های هماهنگ در سراسر لایه های قشر با انعطاف پذیری سیناپس های بازدارنده-2020 In the neocortex, synaptic inhibition shapes all forms
of spontaneous and sensory evoked activity. Importantly,
inhibitory transmission is highly plastic, but
the functional role of inhibitory synaptic plasticity is
unknown. In the mouse barrel cortex, activation of
layer (L) 2/3 pyramidal neurons (PNs) elicits strong
feedforward inhibition (FFI) onto L5 PNs. We find
that FFI involving parvalbumin (PV)-expressing cells
is strongly potentiated by postsynaptic PN burst
firing. FFI plasticity modifies the PN excitation-to-inhibition
(E/I) ratio, stronglymodulates PN gain, and alters
information transfer across cortical layers. Moreover,
our LTPi-inducing protocol modifies firing of L5
PNs and alters the temporal association of PN spikes
to g-oscillations both in vitro and in vivo. All of these
effects are captured by unbalancing the E/I ratio in a
feedforward inhibition circuit model. Altogether, our
results indicate that activity-dependent modulation
of perisomatic inhibitory strength effectively influences
the participation of single principal cortical
neurons to cognition-relevant network activity. |
مقاله انگلیسی |
4 |
Deep learning-assisted adaptive modulation level assignment for video communication over an elastic optical network
تخصیص سطح مدولاسیون انطباقی با کمک یادگیری عمیق برای ارتباط تصویری از طریق شبکه نوری الاستیک-2019 In this paper, we present a user-oriented adaptive modulation level assignment scheme for an elastic optical
network (EON) with a focus on video streaming services. Our objective is to maximize total spectral efficiency
providing the user quality-of-experience (QoE). The proposed adaptive modulation level assignment for video
communication has three stages: network quality-of-transmission (QoT) estimation, extracting the received
video quality based on a proposed utility function and finally applying deep learning to select an appropriate
modulation level that guarantees user QoE with minimum bandwidth utilization. Simulation results show the
efficiency of this approach in increasing the spectral efficiency of the network, especially for long source-destination
distances. This increase in EON spectral efficiency leads to a remarkable decrease in blocking probability
of the network. Keywords: Elastic optical network | Optical fiber | Video communication | Deep learning | Modulation |
مقاله انگلیسی |
5 |
تحلیل لبه ای مبتنی بر موجک چند جهته برای تشخیص سطح توسط پروفیلومتری نوری
سال انتشار: 2019 - تعداد صفحات فایل pdf انگلیسی: 10 - تعداد صفحات فایل doc فارسی: 18 دانشمندان، مهندسان و تولید کنندگان نیاز ضروری به تکنیک های بهتر تشخیص و کنترل کیفیت دارند. مترولوژی نوری با استفاده از علوم نور و علوم کامپیوتر به دنبال شبیه سازی، طراحی، محاسبات و بازرسی برای بسیاری از برنامه های کاربردی علمی و صنعتی مانند اپتیک، مکانیک، هواپیما، الکترونیک و … است. آنالیز الگوی fringe روشی برای انجام برخی عملیات در تصاویر نوری و به منظور دریافت نقشه فاز اینترفرومتری و سپس استخراج برخی اطلاعات مفید از آن است. در این مقاله، بهبود محرک الگوریتم دمدولاسیون fringe محلی ارائه شده است، که بر اساس موجک جدید چند جهته است. کارهای عددی و تجربی در مقایسه با سایر الگوریتم های استاندارد، سود جالبی را نشان می دهد. رویکرد ما به سرعت به عنوان فاز روش های بازیابی پرطرفدار اجرا می شود، اما با دقت قابل توجهی دمدولاسیون fringe های نویز را بهبود می دهد. همه این مسائل بدون هیچ پیش پردازش توسط فیلتر کردن مدل ها رخ می دهد.
کليدواژه ها: تصویربرداری نوری | علوم کامپیوتر | پردازش تصویر | موجک چند جهته | فاز بازیابی | طرح ریزی fringe . |
مقاله ترجمه شده |
6 |
یک آرایه سنسور مبتنی بر پروب برای اثر انگشت بیوتولیول در سرم و ادرار از طریق استراتژی مدولاسیون سورفاکتانت-2019 Enormous efforts have been paid to detection of various biothiols due to their involvements in many physiological
processes. In the present work, we reported a simple fluorescent sensor array for fingerprinting four
different biothiols based on the same probe. The probe was a dual-fluorophore containing pyrene-pyronine FRET
pair and its fluorescence emission could be easily modulated by CTAB surfactant assemblies. The three-element
sensor array was built by simply varying CTAB concentration in the sensor elements that contained the same
probe. The array can produce unique fluorescence fingerprints for four different biothiols and be applied to
discriminate them even in biofluids like serum and urine. This study demonstrates the surfactant modulation
strategy associated with using a FRET dual-fluorophore can offer an opportunity to build simple and effective
fingerprinting sensing platform for multiple biothiols. Keywords: Pyrene | CTAB | Fluorescent sensor array | Biothiols | Pattern recognition |
مقاله انگلیسی |
7 |
In silico and in vivo studies of Astragalus glycyphylloides saponin(s) with relevance to metabolic syndrome modulation
در مطالعات سیلیکون و داخل بدن از گلیسفیلوئیدهای ساپونین آستراگال گلیسفیلوئیدها با ارتباط با مدولاسیون سندرم متابولیک-2019 Triterpenoids are well known modulators of metabolic syndrome. One of the suggested modes of action (MoAs)
involves peroxisome proliferator-activated receptor gamma (PPARγ) binding.
In this study we aimed to: (i) evaluate in silico potential metabolites and PPARγ-mediated MoA of the sapogenin
of the main saponin present in a purified saponins mixture (PSM) from Astragalus glycyphylloides; (ii)
estimate in silico and in vivo PSMs toxicity; and (iii) investigate in vivo antihyperglycaemic, hypolipidaemic,
antioxidant and hepatoprotective effects of PSM.
Metabolites and toxicity were predicted using Meteor and Derek Nexus expert systems (Lhasa Limited) and
PPARγ binding was investigated using the software MOE (CCG Inc.). PSMs acute oral toxicity was evaluated in
mice and the pharmacological effects were assessed in streptozotocin-induced diabetic spontaneously hypertensive
rats (SHRs). Liver histopathology was studied as well.
PPARγ weak partial agonism was predicted in silico for 24 probable/plausible Phase I metabolites which
docking poses were clustered in 12 different binding modes with characteristic protein-ligand interactions. PSMs
beneficial effects on the levels of blood glucose, triglycerides, and total cholesterol, on oxidative stress markers
and liver histology in diabetic SHRs were comparable to those of the PPARγ ligand pioglitazone. PSMs safety
profile was confirmed in silico and in vivo. Keywords: Metabolic syndrome | Saponins | Metabolites | PPARγ | Pharmacophore-based docking | Diabetic spontaneously hypertensive rats |
مقاله انگلیسی |
8 |
Intratumoural immunotherapy: activation of nucleic acid sensing pattern recognition receptors
سیستم ایمنی درمانی داخل رحمی: فعال سازی گیرنده های تشخیص الگوی سنجش اسید نوکلئیک-2019 Recently, it has become clear that the tumour microenvironment (TME) is important in cancer immunotherapy.
While immune checkpoint inhibitors are effective for some patients, the heterogeneous nature and status of the
TME (‘cold’ tumours) play a critical role in suppressing antitumour immunity in non-responding patients. Converting
‘cold’ to ‘hot’ tumours through modulation of the TME may enable expansion of the therapeutic efficacy of
immunotherapy to a broader patient population. This paper describes advances in intratumoural immunotherapy,
specifically activation of nucleic acid sensing pattern recognition receptors to modulate the TME. Keywords: Intratumoral immunotherapy | Modulation of tumour microenvironment | Nucleic acid recognising pattern recognition | receptors | RIG-I | STING | Toll-like receptors |
مقاله انگلیسی |
9 |
Examining redox modulation pathways in the post-mortem frontal cortex in patients with bipolar disorder through data mining of microRNA expression datasets
بررسی مسیرهای مدولاسیون ردوکس پس از مرگ قشر فرونتال بیماران اختلال دو قطبی از طریق داده کاوی میکرو RNA مجموعه داده های بیان -2018 The etiology of redox (reduction and oxidation) alterations in bipolar disorder (BD) is largely unknown. To
explore whether microRNAs targeting redox enzymes may have a role in BD, we examined 3 frontal cortex
microRNA expression datasets (Perkins [2007], Vladimirov [2009], and Miller [2009]; N for BD = 30–36 per
dataset, N for controls = 28–34 per dataset) from the Stanley Neuropathology Consortium. Each dataset was
analyzed separately because they were generated using different high-throughput platforms. Following the se
lection of only redox modulator-targeting microRNAs, microRNAs in the top 10th percentile in feature selection
could together discriminate BD and controls at a greater frequency than expected by chance in classification
analysis. In pathway enrichment analysis of all three datasets, these classifying microRNAs targeted the cellular
nitrogen compound metabolic process pathway, which includes redox enzymes of the mitochondrial electron
transport chain and the glutathione system. To see if this pathway would still emerge as significant if all
microRNAs (not just redox-targeting) were analyzed, all analyses were repeated with the complete set of
microRNAs. Cellular nitrogen compound metabolic process pathway was enriched in all 3 datasets in this
analysis as well, demonstrating that preselection of redox microRNAs was not a requirement to identify this
pathway for the discrimination of BD and controls. While preliminary, our findings suggest that microRNAs that
target redox enzymes in this pathway may be good candidates for the exploration of causative factors con
tributing to redox alterations in BD. Future studies validating these findings in a separate set of central and
peripheral samples are warranted.
Keywords: Bipolar disorder ، microRNA ، Redox modulation ، Data mining ، Oxidative stress ، Mitochondria |
مقاله انگلیسی |
10 |
Market performance implications of modularization: Evidence from global auto firms operating in China
پیامدهای عملکرد بازار از مدولاسیون: شواهد جهانی شرکت های خودرو سازی در چین-2018 Auto firms play an increasingly important role in national economies. However, their internationalization
strategies, especially the trend towards modularization has been underexplored in the international business
literature. Drawing on the resource based theory, we develop hypotheses on the link between modularization
and market performance. Analyzing a sample of 262 auto parts suppliers in China, the study shows the positive
influence of modularization on firm performance and the moderating role of knowledge sharing tools and
physical proximity in this relationship. In addition, these relationships are channeled by firms’ strategic actions
to maintain superior business performance against competitors (firm positional advantage).
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مقاله انگلیسی |