Total Attenuation Research Articles

90-m/560-Mbps underwater wireless optical communication utilizing subband multiple-mode full permutation CAP combined with an SNR-weighted detector and multi-channel DFE.

In this paper, a joint signal processing scheme including a subband multiple-mode full permutation carrierless amplitude phase modulation (SMMP-CAP), signal-to-noise ratio weighted detector (SNR-WD), and multi-channel decision feedback equalizer (MC-DFE) is proposed to mitigate the bandwidth limitation of a high-speed long-reach underwater wireless optical communication (UWOC) system. Referring to the trellis coded modulation (TCM) subset division strategy, 16 quadrature amplitude modulation (QAM) mapping set is divided into four 4-QAM mapping subsets by SMMP-CAP scheme. An SNR-WD and an MC-DFE are employed to enhance the demodulation effect of this system in a fading channel. In a laboratory experiment, the minimal required received optical powers (ROPs) for data rates of 480 Mbps, 600 Mbps, and 720 Mbps, at hard-decision forward error correction (HD-FEC) threshold of 3.80 × 10-3, are -32.7 dBm, -31.3 dBm, and -25.5 dBm, respectively. Moreover, the proposed system successfully achieves a data rate of 560 Mbps in a swimming pool with a transmission distance up to 90 m and a total attenuation measured to be 54.64 dB. To the best of our knowledge, this is the first time to demonstrate a high-speed, long-distance UWOC system by employing an SMMP-CAP scheme.

Assessment of Five Concrete Types as Candidate Shielding Materials for a Compact Radiation Source Based on the IECF

A radiation source based on the inertial electrostatic confinement fusion (IECF) system is being developed for multidisciplinary research applications. The radiation outputs from the IECF system are 2.45 MeV fast neutrons and the associated co-generated X-rays with an energy less than 3 MeV. A radiation shielding study has been performed on five types of concrete to define the most efficient material for the shielding design of the system. The proposed materials were ilmenite-magnetite concrete (IMC), ordinary concrete-1 (OC-1), barite-containing concrete (BC), ordinary concrete-2 (OC-2), and serpentine-containing concrete (SC). A numerical model was applied to determine the effective removal cross-section coefficients (∑Rt) for the fast neutrons and the total mass attenuation coefficients (µm), the half-value layer (HVL), the mean free path (MFP), the effective atomic number (Zeff), and effective electron density (Neff) for photons inside the materials. The model considered the radiation source energy and the material properties of the concrete types. The results revealed that the serpentine-containing concrete exhibited the highest ∑Rt with 12 cm of concrete thickness needed to attenuate an incident neutron flux to 1/100 of its initial value. In addition, the BC shows the highest µm with a 38 cm concrete thickness needed to attenuate the 3 MeV energy X-ray flux to 1/100 of its initial value. This study suggests that a 40 cm thickness of SC or BC adequately shields the radiation generated from an IECF system with a maximum particle production rate of up to 1 × 107 n/s.

A Carrier-Based Low Total Current Ripple Modulation Strategy for Parallel Converters With Leakage Current Attenuation

In order to meet the high performance and low leakage current requirements in high power rating photovoltaic applications, an improved carrier-based modulation (ICBM) for parallel converters is presented in this paper. Different from existing methods which are based on PS-PWM, a proper zero-sequence modulation wave is injected into the three-phase modulation waves to achieve low total current ripple based on the root mean square value analysis of output current ripple. Aside from this, the initial phase shift angles for the carriers in each converter are modified to minimize the excitation source of leakage current, while the quality of total output current is not affected. Furthermore, the proposed ICBM is extended to parallel multilevel converters according to the vector shift principle. By using the proposed ICBM, total current ripple reduction and leakage current attenuation in parallel converters can be achieved simultaneously. Experimental results validated the correctness and effectiveness of the proposed method.

Abstract P3-05-26: Association of muscle mass and density with outcomes in patients with ER positive metastatic breast cancer: correlative analysis of ECOG-ACRIN 2112

Abstract Introduction: Observational data investigating the relationship between body habitus and survival or toxicity in breast cancer has been largely centered in the curative setting and focused on weight- based metrics, with variable and inconsistent results. Muscle is a large, active endocrine organ that affects physical function, drug metabolism, inflammation, and quality of life, but is not adequately measured by body weight alone. Very few studies have evaluated muscle measures in metastatic breast cancer (MBC) and have been focused on patients receiving cytotoxic chemotherapy. Here, we evaluate the impact of muscle mass and muscle density measured on CT scan on outcomes in patients with MBC receiving endocrine- based therapy. Methods: Baseline CT scans done at the time of study enrollment were centrally collected from participants in ECOG-ACRIN E2112, a randomized phase III study of exemestane with or without entinostat in MBC, which ultimately did not impact survival. A transverse cut at the L3 level was extracted and processed using semi-automated SliceOmatic software (Tomovision) by two independent investigators to obtain total body skeletal muscle mass and muscle attenuation. Low muscle mass was defined as skeletal muscle index (SMI, lean muscle area/height, cm2/m2) less than 41 and low skeletal muscle attenuation (SMA) was defined as average muscle density less than 41 HU, or less than 33 HU if the patient is overweight or obese by BMI. Chi-square tests were used to determine the association between SMI and SMA and other clinical characteristics, including body weight, race, and performance status. Multivariable Cox proportional hazard models were used to determine the association between low SMI or low SMA and overall survival (OS), progression free survival (PFS), and patient- reported outcomes. Results: Of the 608 patients randomized in E2112, 546 had analyzable CT scans and follow up data available. 45% (n=246) of participants had obesity by BMI (≥30); 39% (n=212) had low SMI and 56% (n=305) had low SMA. Obese patients were more likely to have higher SMI (p< 0.001); however, 9.5% (n=52) of the study population had both obesity and low SMI. Low SMA was associated with higher rate of obesity and worse performance status (p< 0.001), consistent with muscle quality being a predictor of functional status. Low SMI was not associated with survival outcomes (OS HR 1.04 95%CI 0.83-1.30, PFS HR 1.12 95% CI 0.92-1.36), nor was low SMA (OS HR 1.02 95%CI 0.81-1.28; PFS HR 1.02 95%CI 0.84-1.23). In addition, BMI was not related to survival outcomes. Conclusions: Low muscle mass and low muscle density are prevalent in estrogen receptor positive MBC patients. Muscle measures correlated with obesity and performance status; however, neither low SMI nor low SMA were associated with worse prognosis in this population. Further work is needed to refine body composition measurements and select optimal cutoffs and meaningful endpoints in specific breast cancer populations, particularly in those living with metastatic disease. Citation Format: Tarah J. Ballinger, Gloria Xue, Helga S. Marques, Constantine Gatsonis, Richard Hoffman, Kathy D. Miller, Fengmin Zhao, Joseph Sparano, Roisin Connolly. Association of muscle mass and density with outcomes in patients with ER positive metastatic breast cancer: correlative analysis of ECOG-ACRIN 2112 [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P3-05-26.

A new approach to calculating the ratio of the compton to total, mass attenuation coefficient

X-rays and gamma rays are high-energy radiation that ionize atoms of matter as they pass through them. These rays interact with matter in such a way that secondary rays with energy equal to or lower than the incident photon are produced. The buildup factor is used to estimate the intensity of these secondary rays. One of the methods to calculate the buildup factor is the Geometric Progression formula. To use this formula, the equivalent atomic number must be determined. The ratio of the Compton mass attenuation coefficient to the total mass attenuation coefficient (R) is used to calculate the equivalent atomic number for each compound, element, or mixture. In this research, an equation was introduced to calculate the ratio of the Compton mass attenuation coefficient to the total mass attenuation coefficient (R) for X and gamma rays. This equation was the first of its kind and had good accuracy. It was a two-variable function of energy and atomic number that covered the energy range of 0.015–15 MeV and the range of 4–92 for atomic number. The highest SSE and RMSE fitting errors for the energy component for all calculated elements were equal to 0.000921 and 0.0076, respectively, and the same calculation errors for the atomic number component parameters were equal to 9.5561 and 0.7092, respectively. The maximum relative error of the calculated value with the actual value of water as a composition was less than 6%, and the amount of the same error for lead as an element was less than 9%. This equation can be used in other nuclear codes, as the functions used in it are very straightforward. It reduces the speed of calculations and the volume of calculations for calculating the secondary radiation dose.

Photon attenuations of trichloride of gadolinium by Geant4 and XCom: a comparative study

The total mass attenuation coefficient of trichloride gadolinium has been investigated utilizing Geant4 compared with WinXCom simulation data at energies; 1–10 MeV. The simulated results are used to calculate the total cross section, atomic and electronic cross sections. The aim of this work is to characterize new materials and their interactions with radiation in order to be able for using in shielding or detection. The GdCl3 is applied for super–Kamiokande detector of neutrons. From our comparison study, it is found that the mass attenuation coefficient of GdCl3 with those of two detectors of X-ray (Si and CdTe) is very closed. Also, the total mass transfer attenuation coefficient increases as high energies increases at pairs effect production. From our comparison study, we can predict that GdCl3 can be a good detector of X-ray and concluded that this material has shown good interaction with electromagnetic radiations at high energies.

Ventilated acoustic meta-barrier based on layered Helmholtz resonators

The performance of a multilayer sound attenuating metamaterial with ventilation capacity based on arrays of wall-embedded Helmholtz resonators is investigated analytically, numerically and experimentally. Each cell of the barrier front wall is a Euclidian polygon, such as square or hexagon. One thickness layer of the barrier cell contains a parallel array of 4 (for square cell) or 6 (for hexagon) Helmholtz resonators connected via the axial ventilation duct element. Multiple layers of resonators can be connected in sequence with the extension of the ventilation channel. The sound attenuation performance of the barriers is investigated first using the lumped parameter theory and transfer matrix method (TMM), and numerically using the finite element (FE) simulations solving the Helmholtz equations in frequency domain. These results indicate that the sound attenuation in audible range (300–2000 Hz) can be meaningfully improved using several layers with a unique peak resonance frequency assigned to each corresponding layer, with each additional layer improving the total attenuation. However, it is acknowledged that the previously studied fundamental trade-offs between the total barrier thickness, ventilation capacity, operational frequency range and integral sound attenuation do apply to the proposed design as well. Nevertheless, it is suggested that the simplicity of both structural design and theoretical methods of performance estimations make the suggested barrier a good candidate for applications with a well known desired attenuation spectrum. The impedance tube experiments validate the sound blocking performance and show a reasonable agreement with the numerical predictions.

Sensitivity of seismic attenuation and dispersion to dynamic elastic interactions of connected fractures: Quasi-static finite element modeling study

Prediction of seismic attenuation and dispersion that are inherently sensitive to hydraulic and elastic properties of the medium of interest in the presence of mesoscopic fractures and pores, is of great interest in the characterization of fractured formations. This has been very difficult, however, considering that stress interactions between fractures and pores, related to their spatial distributions, tend to play a crucial role on affecting overall dynamic elastic properties that are largely unexplored. We thus choose to quantitatively investigate frequency-dependent P-wave characteristics in fractured porous rocks at the scale of a representative sample using a numerical scale-up procedure via performing finite element modelling. Based on 2-D numerical quasi-static experiments, effects of fracture and fluid properties on energy dissipation in response to wave-induced fluid flow at the mesoscopic scale are quantified via solving Biot's equations of consolidation. We show that numerical results are sensitive to some key characteristics of probed synthetic rocks containing unconnected and connected fractures, demonstrating that connectivity, aperture and inclination of fractures as well as fracture infills exhibit strong impacts on the two manifestations of WIFF mechanisms in the connected scenario, and on resulting total wave attenuation and phase velocity. This, in turn, illustrates the importance of these two WIFF mechanisms in fractured rocks and thus, a deeper understanding of them may eventually allow for a better characterization of fracture systems using seismic methods. Moreover, this presented work combines rock physics predictions with seismic numerical simulations in frequency domain to illustrate the sensitivity of seismic signatures on the monitoring of an idealized geologic CO2 sequestration in fractured reservoirs. The simulation demonstrates that these two WIFF mechanisms can strongly modify seismic records and hence, indicating that incorporating the two energy dissipation mechanisms in the geophysical interpretation can potentially improving the monitoring and surveying of fluid variations in fractured formations.

Polypropylene/talc/graphene nanoplates (GNP) hybrid composites: Effect of GNP content on the thermal, rheological, mechanical, and electrical properties

AbstractPolypropylene (PP)/talc composites are used extensively in the automotive, aeronautical, and consumer goods industries; however, the increasing demand for more efficient, safe, and less environmentally impact materials makes it necessary to include new reinforcements. In this way, the use of graphene nanoplates (GNP) is a good alternative because this carbon‐based material allows the achievement of new multifunctional nanocomposites with improved properties and process optimization. In this work, PP/talc (80/20) composites were prepared with the addition of 1, 3, 5, and 7 wt% of GNP using the extrusion process and injection molding. Morphological, thermal, rheological, mechanical, electrical, and electromagnetic characterizations were performed. The addition of GNPs led to a linear reduction in the melt flow index (MFI) of the samples. A rheological percolation was observed in the sample with the addition of 7 wt% of GNP. The addition of 5 and 7 wt% of GNP led to significant increases in elastic modulus and Shore D hardness. The electrical and electromagnetic evaluation showed that the increase of GNP in the compositions contributed to improvements in electrical conductivity and permittivity, resulting in a proportional increment in the total attenuation component (SET).

A signal-processing approach to assess viscous-damper absorbing boundary conditions for dry and saturated soils in time domain dynamic problems

For numerical modelling of dynamic problems, absorbing boundary conditions (ABC) are necessary to attenuate reflected waves (’box effect’). Different approaches have been developed for this numerical issue, being the viscous damper (VD-ABC) widely employed. The VD-ABC is not frequency dependent but a total attenuation is never achieved, and hence a tentative enlargement of the computational domain is adopted. Relevant issues on VD-ABC are integrative assessment by a signal processing approach. One and two-phases (dry and saturated soil, respectively) time-domain responses have been considered besides spectral properties and energy content. P-wave velocity has been modified to consider the fluid bulk modulus. ABC affect differently to each variable, being the vertical displacement the less sensible. Higher frequencies present great discrepancies although their energy contribution to the overall signal is not relevant. The results with VD-ABC yield to a feasible reduction of the size of the computational domain, maintaining the required accuracy.

Recent Advances in Attenuation Estimation.

This chapter reviews some of the recent advances in the estimation of the local and the total attenuation, with an emphasis on reducing the bias and variance of the estimates. A special focus is put on describing the effect of power spectrum estimation on bias and variance, the introduction of regularization strategies, as well as on eliminating the need to use reference phantoms for compensating for system dependent effects.

A cascade dead-zone extended state observer for a class of systems with measurement noise

<abstract><p>For high frequency noise, a new $ 2n $-th order cascade extended state observer with dynamic dead-zone structure is proposed in this paper. Dead zone dynamic consists of two parts. One is to "trim" the effect of noise by cutting off the part that falls in the dead zone. The other part pushes the dead zone amplitude to converge to 0 as soon as possible to ensure the convergence of the estimation error. Moreover, in the cascade structure, the high-gain parameter grows only to a second power, thus avoiding excessive amplification of the measurement noise and solving numerical implementation problems. The design procedure ensures that the extended state observer is input-to-state stable. Numerical simulations show the improvement in terms of total disturbance estimation and noise attenuation. The frequency-domain analysis of the proposed ESO using the describing function method investigates the effect of the dead zone nonlinear parameter on the performance of a closed-loop system.</p></abstract>

Loss Tangent Estimation From GPR Data in Complex Medium Scenarios Using Amplitude and Power Spectrum Centroid Frequency Shift Methods

Electromagnetic losses estimation in complex scenarios lacking subsurface continuous reflectors is challenging. We present here a robust approach based on the centroid frequency shift method and Ricker wavelet as the input signal, to compute intrinsic (absorption) losses. The centroid-frequency shift is calculated using the amplitude and power spectrum of records, leading to equations that relate the centroid frequency variation in time to the loss tangent (intrinsic losses). First, the approaches are evaluated and compared by implementation to synthetic Ground Penetrating Radar (GPR) data generated with the gprMax simulator, starting from an inhomogeneous material with spatially smooth dielectric variations. Then, they are applied to real GPR data collected on a fractured basaltic lava flow. The retrieved loss tangent values are compared to the total attenuation estimated from the signal amplitude decay, to evaluate the contribution due to scattering phenomena. The proposed analysis is particularly suitable for GPR data collected in planetary environments, since dielectric losses could be used to constrain the oxide composition of the material as well as scattering losses to determine the amount and distribution of subsurface inhomogeneities.

Effect of Rain Attenuation on Millimeter Wave over Polarization

Millimeter wave has been used in radar applications for a long time, and is increasingly used in new fields, among which high data rate telecommunications is the most prominent. Short wavelength and unique propagation characteristics provide challenges and opportunities for design engineers working in these fields. Millimeter wave has become an indispensable part of 5G mobile communication field due to its excellent spectrum characteristics. In order to help the development of millimeter wave equipment, this paper mainly studies the millimeter wave rain attenuation phenomenon through the combination of theory and simulation. The effects of rainfall rate and polarization mode on millimeter wave propagation attenuation are compared and summarized. In addition, the total attenuation of millimeter wave communication path under different polarization rainfall characteristics is compared. Finally, the total loss of different frequency millimeter wave rainfall links is compared and analyzed. It provides a theoretical basis for the follow-up design and practical application of millimeter wave communication system.

Attenuation and dispersion of leaky Rayleigh wave in polycrystals.

In this work, we use the characteristic equation of leaky Rayleigh waves (LRWs) and a unified approach of bulk waves proposed by Stanke and Kino [J. Acoust. Soc. Am. 75, 665-681 (1984)] to calculate the attenuation and velocity dispersion of LRWs in polycrystals. Numerical results demonstrate that the total attenuation including the leakage attenuation and scattering attenuation is proportional to frequency and independent of grain size in the Rayleigh scattering regime. Meanwhile, the variation of phase velocity in all scattering regimes remains at ∼0.7% according to the theoretical expectation; this means that the velocity dispersion of the LRWs can be ignored, consistent with the conventional viewpoint. Measurements are conducted on stainless steel at different ultrasonic frequencies (all in the Rayleigh scattering regime). The non-paraxial sound field model is used here to eliminate the diffraction loss and to obtain the total attenuation. Experimental results verify that LRWs have very little velocity dispersion. Meanwhile, experimental fitting data reveal that the modified theoretical model can be used to evaluate the total attenuation (only ∼2% discrepancies) of LRWs under the consideration of the diffraction effect. The relative errors between experimental scattering attenuation and theoretical value ranged from 11% to 18%, mainly owing to the effect of surface roughness and measurement inaccuracy.

Determination of microscopic optical properties of agar and Zerdine phantoms at 635 nm using Kubelka-Munk function approach: A numerical study

<p><span>Since the precise and accurate determination of the optical properties of materials is very important for the development and application of optical technology, the investigation of the optical properties of biological tissues with tissue-like phantoms is an important research field in the applications of lasers in medicine. In this study, after directly determining the macroscopic optical properties of the agar and Zerdine phantoms at 635 nm, including the absorbance, transmittance, reflectance, refractive index, and total attenuation coefficient with the single integrating sphere test apparatus; the microscopic optical characterization of these two different soft tissue phantoms were realized at 635 nm by using the Kubelka-Munk function approach. For this, the microscopic optical parameters, which are the absorption coefficient, scattering coefficient, reduced scattering coefficient, and penetration depth, were calculated over these determined macroscopic optical properties.</span></p>

A study for gamma-ray attenuation performances of barite filled polymer composites

In this study, radiation protection efficiency (RPE) for the coded as UP-Ba0, UP-Ba25, UP-Ba50, UP-Ba75 and UP-Ba100 at different sample thicknesses, total mass attenuation coefficient (μ/ρ), linear attenuation coefficients (μ), half value layers (HVL), tenth value layers (TVL), mean free paths (MFP), effective atomic numbers (Zeff) and effective electron densities (NE) were determined at various gamma energies between 59.5 and 1408.0 keV. With the help of the geometric progression (G-P) fitting method, the energy absorption build-up factor (EABF) and exposure build-up factor (EBF) values were calculated in the energy range from 0.015 MeV to 15 MeV for the produced composites. HPGe detector and eight radioactive sources (241Am, 152Eu, 137Cs, 133Ba, 60Co, 57Co, 54Mn and 22Na) were utilized in the experiment. Experimental results were compared with theoretical calculations and it has been observed that there is a good agreement between theoretical and experimental results. It was observed that RPE, μ/ρ, μ, Zeff and NE parameters increased with increasing barite amount and decreased with increasing energy, while the opposite situation was observed in HVL, TVL and MFP parameters. EABF and EBF values increase with increasing penetration depth. As a result, UP-Ba100 is a good radiation absorber according to the other studied barite filled polymer composites.

Generalized formulae for water cooling requirements for the fire safety of hydrocarbon storage tank farms

Cooling water application on hydrocarbon storage tank farms is used to prevent fire propagation between the tanks caused by intense incident radiation on the tanks adjacent to fires. Codes and standards recommendations regarding the spacing between tanks and the cooling water application rate are vague and contradicting. This study investigates a non-traditional technique using Non-Uniform Coolant Application Model (NUCAM) and illustrates the effect of utilizing this technique on coolant and land rationalization in comparison to the traditional uniform application technique. NUCAM investigates the effect of simultaneous fire propagation and domino effect scenarios on the dimensionless incident heat flux in large storage tanks using gasoline and ethanol fires at various Froude Numbers. The cooling water application rate required for total attenuation is investigated based on the rings distribution surrounding the target tank(s) at steady state conditions.Utilizing the non-uniform cooling water application techniques saves up to 59.1% of the cooling water consumption. While the savings in land area reaches 15.6%. NUCAM results regarding single fire scenarios are utilized to develop novel generalized formulae for the incident heat flux and the cooling water application rate taking into consideration the radiation fraction, Froude Number, the relative spacing between the fire and the target tanks and the relative elevation of the target with respect to the fire base. The formulae show flexibility and reliability when applied on large storage tanks range between 42 m and 55 m in diameter. These formulae provide simpler and faster solution approach for investigating the incident heat flux and the cooling water requirements for large atmospheric storage tanks that require complicated computational power for simulation using commercial packages.

Shielding Properties of Glass Samples Containing Li2O, K2O, Na2O, PbO and B2O3 by Geant4, XCOM and Experimental Data

Abstract: In the present work, glass samples containing 10Li2O, 10K2O, 20Na2O. xPbO, (60-x)B2O3 (where x = 0-60) were prepared by the melt quenching method. The shielding parameters of the prepared samples were measured experimentally and calculated theoretically. The measurements have been performed at energies of 356.5, 662, 1173 and 1333 keV to obtain the total mass attenuation coefficient (μm), using a gamma spectrometer containing a shielded NaI (TI) detector. The results of mass attenuation coefficient (μm), half-value layers (HVLs), mean free path (MFP), radiation protection efficiency (RPE), atomic and electronic electron cross-sections (σa and σe), effective atomic number (Zeff) and effective electron number (Neff) were calculated at energies from 1 keV to 100 GeV using the Monte Carlo simulation code Geant4 and XCOM. The calculated results were compared with each other and with the experimental values. Good agreement has been observed. Keywords: Shielding properties, Glass, Photon mass attenuation coefficient, Atomic and electronic cross-sections, Effective atomic and electron numbers, XCOM, Geant4.

What does not kill mesangial cells makes it stronger? The response of the endoplasmic reticulum stress and the O-GlcNAc signaling to ATP depletion

Mesangial cells are modified smooth muscle cells with the ability to modulate glomerular filtration rate (GFR) – a marker of ischemic renal injury. We aimed to determine the role of intracellular O-GlcNAc levels and ER stress in mesangial cells subjected to ATP depletion. Immortalized mouse mesangial cells culture was incubated for 30, 45 and 60 min, or not (control group) with a buffer containing antimycin A and 2-deoxy-d-glucose, inhibitors of ATP synthesis. Mesangial cells subjected to ATPdepletion for 45 min followed by 24 h reperfusion (H45/R24 mesangial cells) promoted 30 % of cell death mainly by necrosis. ATP depletion was sustained throughout reperfusion until 24 h. Resistant H45/R24 mesangial cells presented: (i) low protein content of GFAT, OGT and OGA, however no modification of total O-GlcNAcylation and (ii) attenuation of protein synthesis related to a UPR response mediated by GRP78/PERK/p-eIF2α and a decrease in the protein content of ATF4. The lower activation of apoptosis was related to no alterations in the levels of CHOP and activated caspase 3. We also detected activation of intracellular mediators of necroptosis: IRE1, ATF6, GADD34, ERO1, Mdm2 and P53. The resistant H45/R24 mesangial cells can replenish the cell culture dish indicating that the UPR adaptative response permitted cell survival. Successive ATP depletion induced lower levels O-GlcNAcylation leading to a 30 % cell death in every H/R process. We concluded that lower levels of O-GlcNAcylation and the GRP78/PERK/p-eIF2α UPR response are the molecular mechanisms involved in H45/R24 mesangial cell survival.