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1.
Sensors (Basel) ; 20(5)2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32138331

RESUMO

Damage significantly influences response of a strain sensor only if it occurs in the proximity of the sensor. Thus, two-dimensional (2D) sensing sheets covering large areas offer reliable early-stage damage detection for structural health monitoring (SHM) applications. This paper presents a scalable sensing sheet design consisting of a dense array of thin-film resistive strain sensors. The sensing sheet is fabricated using flexible printed circuit board (Flex-PCB) manufacturing process which enables low-cost and high-volume sensors that can cover large areas. The lab tests on an aluminum beam showed the sheet has a gauge factor of 2.1 and has a low drift of 1.5 µ ϵ / d a y . The field test on a pedestrian bridge showed the sheet is sensitive enough to track strain induced by the bridge's temperature variations. The strain measured by the sheet had a root-mean-square (RMS) error of 7 µ ϵ r m s compared to a reference strain on the surface, extrapolated from fiber-optic sensors embedded within the bridge structure. The field tests on an existing crack showed that the sensing sheet can track the early-stage damage growth, where it sensed 600 µ ϵ peak strain, whereas the nearby sensors on a damage-free surface did not observe significant strain change.

2.
Science ; 366(6467): 838-843, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31672915

RESUMO

The RSC complex remodels chromatin structure and regulates gene transcription. We used cryo-electron microscopy to determine the structure of yeast RSC bound to the nucleosome. RSC is delineated into the adenosine triphosphatase motor, the actin-related protein module, and the substrate recruitment module (SRM). RSC binds the nucleosome mainly through the motor, with the auxiliary subunit Sfh1 engaging the H2A-H2B acidic patch to enable nucleosome ejection. SRM is organized into three substrate-binding lobes poised to bind their respective nucleosomal epitopes. The relative orientations of the SRM and the motor on the nucleosome explain the directionality of DNA translocation and promoter nucleosome repositioning by RSC. Our findings shed light on RSC assembly and functionality, and they provide a framework to understand the mammalian homologs BAF/PBAF and the Sfh1 ortholog INI1/BAF47, which are frequently mutated in cancers.

3.
IEEE Trans Biomed Circuits Syst ; 13(6): 1264-1276, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31634845

RESUMO

Tactile sensing requires form-fitting and dense sensor arrays over large-areas. Hybrid systems, combining Large-Area Electronics (LAE) and silicon-CMOS ICs to respectively provide diverse sensing and high-performance computation/control, enable a platform for such sensing. A key challenge is that hybrid systems require a large number of interfaces between the LAE and CMOS domains, particularly as the number of sensors scales. This paper presents an architecture that exploits the attribute of signal sparsity, commonly exhibited in large-scale tactile-sensing applications, to reduce the interfacing complexity to a level set by the sparsity rather than the number of sensors. This enhances scalability compared to sequential-scanning and active-matrix approaches. The architecture implements compressed sensing via thin-film-transistor (TFT) switches, and is demonstrated in a force-sensing system with 20 force sensors, a TFT die (with 161 ZnO TFTs) per sensor, and a custom CMOS IC for system readout and control. Acquisition error of 0.7 k[Formula: see text] is achieved over a 100 k Ω-20 k Ω sensing range, at energy and rate of 2.46  µ J/frame and 31 fps.

4.
Sensors (Basel) ; 18(6)2018 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-29895727

RESUMO

Sensing sheets based on Large Area Electronics (LAE) and Integrated Circuits (ICs) are novel sensors designed to enable reliable early-stage detection of local unusual structural behaviors. Such a device consists of a dense array of strain sensors, patterned onto a flexible polyimide substrate along with associated electronics. Previous tests performed on steel specimens equipped with sensing sheet prototypes and subjected to fatigue cracking pointed to a potential issue: individual sensors that were on or near a crack would immediately be damaged by the crack, thereby rendering them useless in assessing the size of the crack opening or to monitor future crack growth. In these tests, a stiff adhesive was used to bond the sensing sheet prototype to the steel specimen. Such an adhesive provided excellent strain transfer, but it also caused premature failure of individual sensors within the sheet. Therefore, the aim of this paper is to identify an alternative adhesive that survives minor damage, yet provides strain transfer that is sufficient for reliable early-stage crack detection. A sensor sheet prototype is then calibrated for use with the selected adhesive.

5.
J Clin Diagn Res ; 10(6): PD28-9, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27504355

RESUMO

Inguinal hernia in male is a common problem but having female reproductive organs in hernial sac is rare. It occur because of failure of mullerian duct to regress in a male fetus during embryonic development, result in a syndrome known as Persistent Mullerian Duct Syndrome (PMDS), which is a rare entity of male pseudohermaphroditism. We hereby present a case of 21-year-old male patient reported with complains of cryptorchidism and inguinal hernia. Generally diagnosis of PMDS was established during investigation like ultrasonography, MRI for localization of undescended testis and during surgical exploration for inguinal hernia or cryptorchidism. Our patient was operated by bilateral inguinal incision; hernial sac contained adult size uterus fallopian tube and upper 2/3(rd) of vagina. On karyotyping it was found that he was a case of klinefelter syndrome also. Association of PMDS with klinefelter syndrome is very rare.

6.
IEEE Trans Biomed Circuits Syst ; 9(6): 825-37, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26849205

RESUMO

In wearable and implantable medical-sensor applications, low-energy classification systems are of importance for deriving high-quality inferences locally within the device. Given that sensor instrumentation is typically followed by A-D conversion, this paper presents a system implementation wherein the majority of the computations required for classification are implemented within the ADC. To achieve this, first an algorithmic formulation is presented that combines linear feature extraction and classification into a single matrix transformation. Second, a matrix-multiplying ADC (MMADC) is presented that enables multiplication between an analog input sample and a digital multiplier, with negligible additional energy beyond that required for A-D conversion. Two systems mapped to the MMADC are demonstrated: (1) an ECG-based cardiac arrhythmia detector; and (2) an image-pixel-based facial gender detector. The RMS error over all multiplication performed, normalized to the RMS of ideal multiplication results is 0.018. Further, compared to idealized versions of conventional systems, the energy savings obtained are estimated to be 13× and 29×, respectively, while achieving similar level of performance.


Assuntos
Arritmias Cardíacas/fisiopatologia , Técnicas Biossensoriais/instrumentação , Algoritmos , Eletrocardiografia , Desenho de Equipamento , Humanos
7.
PLoS One ; 8(5): e64798, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23741394

RESUMO

Gene expression is a multi-step process which requires recruitment of several factors to promoters. One of the factors, Sen1p is an RNA/DNA helicase implicated in transcriptional termination and RNA processing in yeast. In the present study, we have identified a novel function of Sen1p that regulates the expression of ribonucleotide reductase RNR1 gene, which is essential for maintaining genomic integrity. Cells with mutation in the helicase domain or lacking N-terminal domain of Sen1p displayed a drastic decrease in the basal level transcription of RNR1 gene and showed enhanced sensitivity to various DNA damaging agents. Moreover, SEN1 mutants [Sen1-1 (G1747D), Sen1-2 (Δ1-975)] exhibited defects in DNA damage checkpoint activation. Surprisingly, CRT1 deletion in Sen1p mutants (Sen1-1, Sen1-2) was partly able to rescue the slow growth phenotype upon genotoxic stress. Altogether, our observations suggest that Sen1p is required for cell protection against DNA damage by regulating the expression of DNA repair gene RNR1. Thus, the misregulation of Sen1p regulated genes can cause genomic instability that may lead to neurological disorders and premature aging.


Assuntos
DNA Helicases/metabolismo , Regulação Fúngica da Expressão Gênica , RNA Helicases/metabolismo , Ribonucleotídeo Redutases/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Núcleo Celular/metabolismo , Cromatina/metabolismo , Dano ao DNA/efeitos dos fármacos , Dano ao DNA/genética , DNA Helicases/genética , Deleção de Genes , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Instabilidade Genômica , Mutagênicos/farmacologia , Mutação , Fenótipo , Ligação Proteica , Inibidores de Proteínas Quinases/farmacologia , Transporte Proteico , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , RNA Helicases/genética , Proteínas Repressoras/genética , Saccharomyces cerevisiae/efeitos dos fármacos , Proteínas de Saccharomyces cerevisiae/antagonistas & inibidores
8.
Nano Lett ; 13(6): 2634-9, 2013 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-23635097

RESUMO

The ability to three-dimensionally interweave biological tissue with functional electronics could enable the creation of bionic organs possessing enhanced functionalities over their human counterparts. Conventional electronic devices are inherently two-dimensional, preventing seamless multidimensional integration with synthetic biology, as the processes and materials are very different. Here, we present a novel strategy for overcoming these difficulties via additive manufacturing of biological cells with structural and nanoparticle derived electronic elements. As a proof of concept, we generated a bionic ear via 3D printing of a cell-seeded hydrogel matrix in the anatomic geometry of a human ear, along with an intertwined conducting polymer consisting of infused silver nanoparticles. This allowed for in vitro culturing of cartilage tissue around an inductive coil antenna in the ear, which subsequently enables readout of inductively-coupled signals from cochlea-shaped electrodes. The printed ear exhibits enhanced auditory sensing for radio frequency reception, and complementary left and right ears can listen to stereo audio music. Overall, our approach suggests a means to intricately merge biologic and nanoelectronic functionalities via 3D printing.


Assuntos
Biônica , Orelha , Engenharia Tecidual , Humanos , Nanopartículas
9.
J Biol Chem ; 288(26): 18743-57, 2013 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-23673664

RESUMO

Clipping of histone tails has been reported in several organisms. However, the significance and regulation of histone tail clipping largely remains unclear. According to recent discoveries H3 clipping has been found to be involved in regulation of gene expression and chromatin dynamics. Earlier we had provided evidence of tissue-specific proteolytic processing of histone H3 in White Leghorn chicken liver nuclei. In this study we identify a novel activity of glutamate dehydrogenase (GDH) as a histone H3-specific protease in chicken liver tissue. This protease activity is regulated by divalent ions and thiol-disulfide conversion in vitro. GDH specifically clips H3 in its free as well as chromatin-bound form. Furthermore, we have found an inhibitor that inhibits the H3-clipping activity of GDH. Like previously reported proteases, GDH too may have the potential to regulate/modulate post-translational modifications of histone H3 by removing the N-terminal residues of the histone. In short, our findings identify an unexpected proteolytic activity of GDH specific to histone H3 that is regulated by redox state, ionic concentrations, and a cellular inhibitor in vitro.


Assuntos
Regulação Enzimológica da Expressão Gênica , Glutamato Desidrogenase/metabolismo , Histonas/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Encéfalo/enzimologia , Galinhas , Cromatina/metabolismo , Cisteína Proteases/metabolismo , Dissulfetos , Epigênese Genética , Glutamato Desidrogenase/sangue , Histonas/sangue , Concentração de Íons de Hidrogênio , Fígado/enzimologia , Espectrometria de Massas , Camundongos , Dados de Sequência Molecular , Ratos , Proteínas Recombinantes/metabolismo , Sais , Compostos de Sulfidrila , Temperatura
10.
Nat Commun ; 3: 763, 2012 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-22453836

RESUMO

Direct interfacing of nanosensors onto biomaterials could impact health quality monitoring and adaptive threat detection. Graphene is capable of highly sensitive analyte detection due to its nanoscale nature. Here we show that graphene can be printed onto water-soluble silk. This in turn permits intimate biotransfer of graphene nanosensors onto biomaterials, including tooth enamel. The result is a fully biointerfaced sensing platform, which can be tuned to detect target analytes. For example, via self-assembly of antimicrobial peptides onto graphene, we show bioselective detection of bacteria at single-cell levels. Incorporation of a resonant coil eliminates the need for onboard power and external connections. Combining these elements yields two-tiered interfacing of peptide-graphene nanosensors with biomaterials. In particular, we demonstrate integration onto a tooth for remote monitoring of respiration and bacteria detection in saliva. Overall, this strategy of interfacing graphene nanosensors with biomaterials represents a versatile approach for ubiquitous detection of biochemical targets.


Assuntos
Técnicas Biossensoriais , Esmalte Dentário/microbiologia , Grafite/farmacologia , Nanotecnologia/métodos , Dente/microbiologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Materiais Biocompatíveis , Escherichia coli/isolamento & purificação , Helicobacter pylori/isolamento & purificação , Humanos , Nanoestruturas , Saliva/microbiologia , Staphylococcus aureus/isolamento & purificação
11.
Artigo em Inglês | MEDLINE | ID: mdl-22254438

RESUMO

Low-power devices that can detect clinically relevant correlations in physiologically-complex patient signals can enable systems capable of closed-loop response (e.g., controlled actuation of therapeutic stimulators, continuous recording of disease states, etc.). In ultra-low-power platforms, however, hardware error sources are becoming increasingly limiting. In this paper, we present how data-driven methods, which allow us to accurately model physiological signals, also allow us to effectively model and overcome prominent hardware error sources with nearly no additional overhead. Two applications, EEG-based seizure detection and ECG-based arrhythmia-beat classification, are synthesized to a logic-gate implementation, and two prominent error sources are introduced: (1) SRAM bit-cell errors and (2) logic-gate switching errors ('stuck-at' faults). Using patient data from the CHB-MIT and MIT-BIH databases, performance similar to error-free hardware is achieved even for very high fault rates (up to 0.5 for SRAMs and 7 × 10(-2) for logic) that cause computational bit error rates as high as 50%.


Assuntos
Arritmias Cardíacas/diagnóstico , Interpretação Estatística de Dados , Fontes de Energia Elétrica , Eletrocardiografia/instrumentação , Eletroencefalografia/métodos , Falha de Equipamento , Convulsões/diagnóstico , Algoritmos , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Processos Estocásticos
12.
Conf Proc IEEE Eng Med Biol Soc ; 2011: 2184-7, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22254772

RESUMO

To make it viable for remote monitoring to scale to large patient populations, the accuracy of detectors used to identify patient states of interests must improve. Patient-specific detectors hold the promise of higher accuracy than generic detectors, but the need to train these detectors individually for each patient using expert labeled data limits their scalability. We explore a solution to this challenge in the context of atrial fibrillation (AF) detection. Using patient recordings from the MIT-BIH AF database, we demonstrate the importance of patient specificity and present a scalable method of constructing a personalized detector based on active learning. Using a generic detector having a sensitivity of 76% and a specificity of 57% as its seed, our active learning approach constructs a detector with a sensitivity of 90% and specificity of 85%. This performance approaches that of a patient-specific detector, which has a sensitivity of 94% and specificity of 85%. By selectively choosing examples for training, the active learning approach reduces the amount of expert labeling needed by almost eight fold (compared to the patient-specific detector) while achieving accuracy within 99%.


Assuntos
Algoritmos , Inteligência Artificial , Fibrilação Atrial/diagnóstico , Diagnóstico por Computador/métodos , Eletrocardiografia/métodos , Reconhecimento Automatizado de Padrão/métodos , Medicina de Precisão/métodos , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
13.
Annu Rev Biomed Eng ; 10: 247-74, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18647116

RESUMO

The electronics of a general biomedical device consist of energy delivery, analog-to-digital conversion, signal processing, and communication subsystems. Each of these blocks must be designed for minimum energy consumption. Specific design techniques, such as aggressive voltage scaling, dynamic power-performance management, and energy-efficient signaling, must be employed to adhere to the stringent energy constraint. The constraint itself is set by the energy source, so energy harvesting holds tremendous promise toward enabling sophisticated systems without straining user lifestyle. Further, once harvested, efficient delivery of the low-energy levels, as well as robust operation in the aggressive low-power modes, requires careful understanding and treatment of the specific design limitations that dominate this realm. We outline the performance and power constraints of biomedical devices, and present circuit techniques to achieve complete systems operating down to power levels of microwatts. In all cases, approaches that leverage advanced technology trends are emphasized.


Assuntos
Engenharia Biomédica/instrumentação , Fontes de Energia Elétrica/tendências , Eletrônica Médica/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Telemetria/instrumentação , Engenharia Biomédica/tendências , Eletrônica Médica/tendências , Transferência de Energia , Desenho de Equipamento , Avaliação da Tecnologia Biomédica , Telemetria/tendências
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