Alternative Sampling Research Articles

Industry influence on firms' R&D and innovation

AbstractThis paper examines the effect of peers on a firm's research and development (R&D) policy. We show that firms do not make R&D decisions in isolation, and that industry dynamics play an important role in defining a firm's R&D intensity. Using a large sample of 54,393 firm‐year observations from 1991 to 2015 in the United States, we find that firms' R&D decisions are mainly driven by their industry peers' R&D policies. Moreover, we find that R&D mimicking is significant only in the presence of strong product market competition, whereas we do not find any evidence of information‐based herding in R&D investments. Our additional analysis shows that our main conclusions remain valid even in the presence of financial constraints, and regardless of the firms' market positions. Finally, we provide evidence that R&D mimicking increases firms' future values, future patent outputs, and estimated patent dollar values. Our findings are robust to endogeneity concerns, and to using alternative sample compositions, R&D intensity proxies, and different industry classifications.

Optimization and Improvement of qPCR Detection Sensitivity of SARS-CoV-2 in Saliva.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major public health threat globally, especially during the beginning of the pandemic in 2020. Reverse transcription-quantitative PCR (RT-qPCR) is utilized for viral RNA detection as part of control measures to limit the spread of COVID-19. Collecting nasopharyngeal swabs for RT-qPCR is a routine diagnostic method for COVID-19 in clinical settings, but its large-scale implementation is hindered by a shortage of trained health professionals. Despite concerns over its sensitivity, saliva has been suggested as a practical alternative sampling approach to the nasopharyngeal swab for viral RNA detection. In this study, we spiked saliva from healthy donors with inactivated SARS-CoV-2 from an international standard to evaluate the effect of saliva on viral RNA detection. On average, the saliva increased the cycle threshold (CT) values of the SARS-CoV-2 RNA samples by 2.64 compared to the viral RNA in viral transport medium. Despite substantial variation among different donors in the effect of saliva on RNA quantification, the outcome of the RT-qPCR diagnosis was largely unaffected for viral RNA samples with CT values of <35 (1.55 log10 IU/mL). The saliva-treated viral RNA remained stable for up to 6 h at room temperature and 24 h at 4°C. Further supplementing protease and RNase inhibitors improved the detection of viral RNA in the saliva samples. Our data provide practical information on the storage conditions of saliva samples and suggest optimized sampling procedures for SARS-CoV-2 diagnosis. IMPORTANCE The primary method for detection of SARS-CoV-2 is using nasopharyngeal swabs, but a shortage of trained health professionals has hindered its large-scale implementation. Saliva-based nucleic acid detection is a widely adopted alternative, due to its convenience and minimally invasive nature, but the detection limit and direct impact of saliva on viral RNA remain poorly understood. To address this gap in knowledge, we used a WHO international standard to evaluate the effect of saliva on SARS-CoV-2 RNA detection. We describe the detection profile of saliva-treated SARS-CoV-2 samples under different storage temperatures and incubation periods. We also found that adding protease and RNase inhibitors could improve viral RNA detection in saliva. Our research provides practical recommendations for the optimal storage conditions and sampling procedures for saliva-based testing, which can improve the efficiency of COVID-19 testing and enhance public health responses to the pandemic.

First-Day-of-Life Rectal Swabs Fail To Represent Meconial Microbiota Composition and Underestimate the Presence of Antibiotic Resistance Genes.

The human gut microbiome plays a vital role in health and disease. In particular, the first days of life provide a unique window of opportunity for development and establishment of microbial community. Currently, stool samples are known to be the most widely used sampling approach for studying the gut microbiome. However, complicated sample acquisition at certain time points, challenges in transportation, and patient discomfort underline the need for development of alternative sampling approaches. One of the alternatives is rectal swabs, shown to be a reliable proxy for gut microbiome analysis when obtained from adults. Here, we compare the usability of rectal swabs and meconium paired samples collected from infants on the first days of life. Our results indicate that the two sampling approaches display significantly distinct patterns in microbial composition and alpha and beta diversity as well as detection of resistance genes. Moreover, the dissimilarity between the two collection methods was greater than the interindividual variation. Therefore, we conclude that rectal swabs are not a reliable proxy compared to stool samples for gut microbiome analysis when collected on the first days of a newborn's life. IMPORTANCE Currently, there are numerous suggestions on how to ease the notoriously complex and error-prone methodological setups to study the gut microbiota of newborns during the first days of life. Especially, meconium samples are regularly failing to yield meaningful data output and therefore have been suggested to be replaced by rectal swabs as done in adults as well. We find this development toward a simplified method to be producing dramatically erroneous results, skewing data interpretation away from the real aspects to be considered for neonatal health during the first days of life. We have put together our knowledge on this critical aspect with careful consideration and identified the failure of rectal swabs to be a replacement for sampling of meconium in term-born newborns.

Dried blood spots for doping controls-Development of a comprehensive initial testing procedure with fully automated sample preparation.

Currently, primarily urine, whole blood and serum samples are analyzed for doping-relevant substances in professional sports, but recently dried blood spots (DBS) have been introduced as complementary matrix, offering advantageous features, e.g. a minimally invasive sampling procedure. In order to cope with the increased application of DBS, a comprehensive initial testing procedure (ITP) was developed, optimized and validated, comprising a total of 233 substances representing all groups on the World Anti-Doping Agency's (WADA's) Prohibited List. The sample preparation was conducted by employing a fully automated system using an efficient flow-through extraction of a 4mm diameter spot followed by LC-HRMS/MS analysis. The procedure was successfully validated in terms of selectivity, limit of detection, reproducibility, carryover and robustness with respect to an alternative manual sample preparation, an alternative dried blood collection device and the sample extract stability, and was thus found to meet the required criteria of the relevant guidelines published by WADA for routine application. As a proof-of-concept, DBS samples were analyzed after the administration of the glucocorticoids prednisone and dexamethasone, as well as the stimulant pseudoephedrine and the beta-blocker propranolol. All substances were detected in post-administration samples for at least 4h and up to 24 h after intake, depending on the collection time period, using the developed testing procedure. In particular, for substances that are only banned in-competition, data obtained from DBS samples can be useful for the interpretation of adverse analytical findings. In conclusion, the developed ITP accounts for the anticipated increasing relevance of DBS in anti-doping analysis in the future and provides a foundation for optimized approaches for specific substance classes.

The influence of institutional pressure on target setting

We examine whether the desire to maintain sociopolitical legitimacy with critical stakeholders affects sales targets set by Chinese firms. Drawing from institutional theory, we argue that enterprises owned by local government (local-SOEs) feel greater pressure to maintain their legitimacy with the local government relative to private firms (non-SOEs), leading to a stronger association between the provincial GDP target (a legitimate benchmark) and firm-level targets. Results from manually collected data support this conjecture and are robust to alternate measures and samples. Increases in the demand for legitimacy -- measured using exogenous shocks and sample characteristics -- strengthen the association. Finally, changes in the coverage in the official press and changes in target achievement rates document the real effects of this strategy. Our findings demonstrate the effects of institutional pressures on corporate decisions and enrich our understanding on the socially constructed as well as instrumental rationality role of management accounting.

In the case of extensively putrefied bodies, the analysis of entomological samples may support and complement the toxicological results obtained with other alternative matrices

Entomotoxicological analysis is not part of routine toxicological analysis. This work aims to present two cases to illustrate the potential of entomological samples as complementary matrices to identify substances in cases of advanced putrefaction. (Case#1) A woman wasexhumed after 14 months to ascertain the exact cause of death. She died after six weeks of hospitalization because of intestinal ischemia followed by multiorgan failure. (Case#2) The corpse of a woman, known to have a psychiatric disorder, was discovered in her apartment. The state of decomposition of the body was consistent with a post-mortem period of several weeks (approximately 6 weeks). Toxicological investigations were performed in the biological and entomological samples of case#1 (hair, adipocere, brain, and pupae) and of case#2 (hair, bone, flies, and pupae) using liquid chromatography with high-resolution mass spectrometry and tandem mass spectrometry detection methods. In case#1, several drugs and metabolites were detected. In particular, the pupae analyses allowed the objectification of morphine administration, whereas morphine was only found in adipocere, but not in hair nor in brain. In case#2, the pupae analyses allowed the detection of three metabolites of quetiapine, and the flies analyses allowed the detection of valpromide, which was only detected in hair. In conclusion, the pupae and flies analyses in these two cases complemented the results obtained in the other alternative biological samples, which may guide hypotheses about the possible causes of death. Nevertheless, additional data and case reports would be of benefit to assess the value of entomotoxicology in routine forensic investigations.

Disentangled oil shocks and stock market volatility in Nigeria and South Africa: A GARCH-MIDAS approach

In this study, we investigate the effects of disentangled oil shocks on the volatility of the stock markets of Nigeria and South Africa using the Mixed Data Sampling variant of the Generalized Autoregressive Conditional Heteroscedasticity (GARCH-MIDAS) model. The disentangled oil shocks involve oil supply shock, economic activity shock, oil consumption demand shock, and oil inventory demand shock covering January 2010 and July 2022. Overall, we find that the stock market volatilities of Nigeria and South Africa respond similarly to oil supply shock and oil consumption demand shock but differently to economic activity shock and oil inventory demand shock. The unusual increase in the volatility of Nigeria’s stock market has been attributed to the loss of investors’ confidence which takes a too long time to be restored. Our results are robust to alternative forecast sampling techniques, particularly fixed and rolling windows.

Effective sampling for drift mitigation in machine learning using scenario selection: A microgrid case study

Predictive modeling is pervasive across a variety of industries (e.g., driving patterns in insurance, fraud detection in finance, and forecasting in energy). However, the deterioration of prediction accuracy for most machine learning (ML) models due to the drift is inevitable despite having acceptable performance in a test setting. Drift is a natural occurrence as cumulative information changes over time but should be regulated to ensure an ML model’s prediction remains relevant in real-time when decisions are being made. This study proposes a drift mitigation framework (DMF) to obtain an effective sample size in a scalable and unbiased manner for sustainable predictive performance from ML models using microgrids (MGs) as a testbed. Scenario selection was used as an alternative sampling technique to obtain an effective sample from historical data contributing to probability theory. These scenarios were evaluated using a quantile-quantile (Q-Q) plot, Welch’s T-test, and relative entropy measures to ensure the obtained sample effectively captures the general population behavior. The results showed two of the three climate factors used in our experiment formed a nearly straight line on their Q-Q plots, suggesting the effective sample retained comparable statistical properties to theoretical distributions fitted to the original population and complete training data. At an alpha equal to 0.05, a hypothesis test was conducted with the null hypothesis claiming the means of reduced and complete data were statistically equivalent for ambient temperature, solar irradiance, and wind speed. The p-values obtained for each stochastic climate factor were 1.01, 0.296, and 4.13 suggesting insufficient evidence to reject the null hypothesis. Similarly, the resulting population stability index (PSI) values for each stochastic climate factor were 0.175, 0.352, and 0.023 respectively. Hence, there was no significant shift between the population data and the effective sample across each factor.

Acceleration of indirect detection 195Pt solid-state NMR experiments by sideband selective excitation or alternative indirect sampling schemes

The measurement of the of chemical shift (CS) tensors via solid-state NMR (ssNMR) spectroscopy has proven to be a powerful probe of structure for organic molecules, biomolecules, and inorganic materials. However, when measuring the NMR spectra of heavy spin-1/2 isotopes the chemical shift anisotropy (CSA) is commonly on the order of thousands of parts per million, which makes acquisition of NMR spectra difficult due to the low NMR sensitivity imposed by the breadth of the signals and challenges in uniformly exciting the NMR spectrum. We have recently shown that complete 195Pt NMR spectra could be rapidly measured by using 195Pt saturation or excitation selective long pulses (SLP) with multiple rotor-cycle durations and RF fields less than 50 kHz into 1H{195Pt} or 1H-31P{195Pt} PE S-RESPDOR, TONE D-HMQC-4, J-resolved, and J-HMQC pulse sequences. The SLP only provide signal or dephasing when they are applied on resonance with a spinning sideband. The magic angle spinning 195Pt NMR spectrum is reconstructed in the sideband selective NMR experiments by acquiring 1D NMR spectra at variable 195Pt pulse offsets. In this work, we present a detailed investigation of the specific pulse conditions required for the ideal performance of sideband selective experiments. Sideband selective experiments are shown to be able to accurately reproduce MAS NMR spectra with minimal distortions of relative sideband intensities. It is also demonstrated that a 195Pt NMR spectrum indirectly detected with HMQC can be rapidly obtained by acquiring a single rotor cycle of indirect dimension evolution points. We dub this method One Rotor Cycle of Acquisition (ORCA) HMQC. Sideband selective experiments and ORCA HMQC experiments are shown to provide a one order of magnitude improvement in experiment times as compared to conventional wideline HMQC experiments.

Surgical mask as an alternative sampling site for gunshot residue analysis

Gunshot residue (GSR) has been identified in the oro-nasal cavities and in various areas of the face. However, there is no study in the literature about the outcome of the analysis if the mouth and nose are covered with a mask. The purpose of this study is to experimentally ascertain whether GSR detection can be made on surgical masks. Twelve civilians wearing facemasks were divided into six groups of two, each consisting of a shooter and an accompanying person. A single shot was fired by the mask wearing shooters of all six groups in an outdoor and indoor shooting range. The inner surface, outer surface, and strap of the mask were the three areas where we investigated for the presence of GSR. GSR particle counts of the shooter were higher than those of accompanying person. Analysis after outdoor range shootings yielded fewer particles than indoor range shootings. The most particles were detected on the outer surface of the masks, and the least on the inner surface. All analyzes performed on the shooters' mask revealed significantly higher number of particles compared to accompanying persons. The results showed a significant difference in the quantity of GSR particles identified, which could aid in distinguishing between the shooter and the accompanying person. The outer surface of the mask has been determined to be the most useful sampling location in this regard, as it is the sample where the difference is most prominent.

Determining the Geogenic Radon Potential in Different Layouts and Numbers of Points

The geogenic radon potential is primarily controlled by the geological characteristics of the site, such as the rock type and structural elements, as well as the permeability of the soil. Depending on the scope of the survey, the geogenic radon potential can be mapped based on measurements conducted in the field at various resolutions. Detailed surveys are generally labour-intensive and time-consuming. Therefore, a balance should be reached between the desired level of precision and the required amount of effort, delivering the best results with the least number of resources. The international literature describes a variety of surveying techniques. This study was undertaken in a region of the central zone of the Poiana Rusca Mountains (Southern Carpathians, Romania) that contains several metamorphic, volcanic, and sedimentary rock types. The primary objective of the study is to compare alternative sampling point configurations, which vary in number and arrangement. The objective was to achieve the most accurate representation of the calculated geogenic radon potential while limiting the number of measurements and the time and effort associated with them. Radon activity concentration and soil permeability data were collected from 34 locations using seven alternative layouts of the sampling points. The proposed layouts were based on various configurations of fifteen, nine, five, and three sampling points. Locally, in some of the metamorphic units and in the regions containing sedimentary deposits with volcanic intercalations, the geogenic radon potential was found to be elevated. The results indicate that the three-measuring-point configuration is acceptable for general geogenic radon potential surveys.

New Trend in Toxicological Screening Using Volumetric Absorptive Microsampling (VAMS) and High-Resolution Mass Spectrometry (HR/MS) Combination.

In toxicology, screenings are routinely performed using chromatographic methods coupled to detection systems such as high-resolution mass spectrometry (HR/MS). The increase in specificity and sensitivity of HRMS is responsible for the development of methods for alternative samples such as Volumetric Adsorptive Micro-Sampling. Whole blood overloaded with 90 drugs was sampled with 20 µL MitraTM to optimize the pre-analytical step as well as to determine the identification limits of drugs. Elution of chemicals was carried out in a solvent mixture through agitation and sonication. After dissolution, 10 μL was injected into the chromatographic system coupled to the OrbitrapTM HR/MS. Compounds were confirmed against the laboratory library. The clinical feasibility was assessed in fifteen poisoned patients using the simultaneous sampling of plasma, whole blood and MitraTM. The optimized extraction procedure allowed us to confirm 87 compounds out of the 90 present in the spiked whole blood. Cannabis derivatives were not detected. For 82.2% of the investigated drugs, the identification limits were below 12.5 ng·mL-1, with the extraction yields ranging from 80.6 to 108.7%. Regarding the patients' analysis, 98% of the compounds in plasma were detected in MitraTM compared to whole blood, with a satisfying concordance (R2 = 0.827). Our novel screening approach opens new insights into different toxicologic fields appropriate for pediatrics, forensics or to perform mass screening.

Political economy of real exchange rate levels

Voluminous theoretical and empirical research shows that real exchange rate (RER) undervaluation could be conducive to economic development. Why do countries then often avoid the pursuit of policies that facilitate undervaluation or even intentionally pursue RER overvaluation? We address this question by investigating economic, institutional, and policy factors that help explain the within-country variation in RER undervaluation in a baseline panel of 68 developing and 39 developed countries between 1989–2013 using OLS and GMM estimators. Our results indicate that increases in the share of non-tradable sector output, imported input intensity of exports, and capital account openness is systematically associated with less undervalued RERs. We also provide evidence that independent central banks and democratic institutions are linked to RER overvaluation. Our key findings are robust to using alternative specifications, measures, estimation techniques, samples, and additional control variables. A preliminary comparison of Latin America and East Asia suggests interesting support for our key findings.

Putting Meat to the Test: Imaging and Mechanical Testing Used to Understand the Properties of Meat Alternatives and How They Mimic Our Typical Meat Sensory Experience

AbstractAn increasing number of consumers incorporate plant-based products and meat alternatives into their diet. Researchers at Reading Scientific Services Ltd. (RSSL) have performed tensile testing on both chicken and plant-based chicken alternative samples. Using a Linkam MFS stage, the team has assessed the failure point and breaking pattern of each of the samples, to determine which plant-protein product behaved most similarly to the chicken sample. This research offers a path for manufacturers in the meat alternatives industry to better understand the textural differences between chicken and alternative products, and can help inform future new product development for manufacturers looking to expand their product offering.

Abstract 5298: Multiplex immunoassay characterization of 48 cytokines, chemokines, and growth factors in colorectal cancer

Abstract Cytokines, chemokines, and growth factors are critical mediators of immune system function capable of signaling through autocrine, paracrine, and endocrine mechanisms. Their pleiotropic immunomodulatory properties allow these biomolecules to react to diverse stimuli and regulate the immune response. We developed a novel immunoassay, using Luminex xMAP technology, for the simultaneous measurement of 48 cytokines, chemokines, and growth factors in serum, plasma, and cell culture supernatant. Many of these proteins have been proposed as biomarkers of colorectal cancer (CRC) and as key regulators of the tumor microenvironment (TME). While this complex milieu can support antitumor immunity, CRC is frequently characterized by chronic inflammation driving disease progression, with the TME serving as a potent reservoir from which the cytokines, chemokines, and growth factors exert their influence. The MILLIPLEX Human Cytokine/Chemokine/Growth Factor Panel B (HCYTB-60K) assays were performed in 96-well plates and run on the Luminex LX200™ instrument. Data was acquired via xPONENT v. 4.3 software. Data analysis was performed for all immunoassays using the Belysa Immunoassay Curve Fitting Software. Commercially available serum samples obtained from colorectal cancer patients and healthy controls were evaluated for cytokine, chemokine, and growth factor expression. Of the 48 analytes tested, statistically significant increases in BAFF, sFas, SCF, and MPIF-1 were observed in colorectal cancer serum. In contrast, IL-20 and ENA-78 decreased relative to healthy controls. While the immunoassay was verified for measurement of serum and plasma samples, additional sample types may be of interest to cancer researchers. Therefore, we evaluated the ability of the 48-plex immunoassay to measure these biomarkers in CSF, urine, milk, tumor samples and exosomal isolates, establishing a profile for these proteins in each sample type. Altogether, this study uses a novel multiplex immunoassay to characterize the immunological profile of colorectal cancer serum, focusing on 48 cytokines, chemokines, and growth factors. Additionally, alternative sample types were evaluated to establish the utility of this technology for applications beyond serum, plasma, and cell culture supernatant. Citation Format: Wen-Rong Lie, Harold Steiner, Sasha Williams, Munmun Banerjee, Anthony Saporita, Brooke Gilliam, Qiang Xiao. Multiplex immunoassay characterization of 48 cytokines, chemokines, and growth factors in colorectal cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5298.

Tradeoff between corporate investment and CSR: The moderating effect of financial slack, workforce slack, and board gender diversity

This paper investigates the existence of a tradeoff between corporate investment (i.e., tangible and intangible) and corporate social responsibility (CSR) in the presence of the moderating effects of financial slack, human resources slack, and board gender diversity. Based on an international sample of 44,129 firm-year observations between 2005 and 2019, we find that corporate investment leads to significantly lower CSR engagement in all three pillars (i.e., environmental, social, and governance). Furthermore, while financial slack positively moderates between corporate investment and CSR, human resources slack and board gender diversity negatively moderate between corporate investment and CSR. This outcome is robust in terms of endogeneity concerns, alternative sampling, alternative investment proxies, CSR regulations, and timing impacts. Hence, we find the dominance of the shareholders' perspective rather than the stakeholders' perspective. The results outline the tradeoff between corporate investment and CSR and the role of contingencies in this tradeoff relationship.

Phonon Sampling Method for Inelastic Thermal Neutron Scattering Events

Accurate representation of thermal neutron scattering in Monte Carlo transport simulations requires that the molecular vibrations of the target material be accounted for. Historically, this has been achieved by precomputing large multidimensional tables that are a function of temperature and the cosine of the scattering angle, as well as incoming and outgoing neutron energy. Most commonly used sampling techniques for thermal neutron scattering rely on large multidimensional tables, where higher resolution results in an increase in required memory and attempts to reduce memory can result in grid coarseness errors. An alternative sampling method is introduced here that is a significant departure from precomputed tables and instead relies on a more physical model of the scattering behavior. The phonon sampling method classifies neutron scattering events by the number of phonons excited/de-excited during the scattering collision. In doing so, energy exchange may be obtained via rejection sampling, and an analytical representation of the momentum exchange is obtained. This sampling method has been tested on graphite, yttrium hydride, and uranium nitride, and preliminary implementation of the phonon sampling method shows accurate results for angular and energy distributions, though resulting in up to a 40% slowdown in overall calculation time. This notable slowdown is countered, however, by a large reduction in storage (over 99% reduction compared to standard multidimensional tables).

Retail investors' accessibility to the internet and firm-specific information flows: Evidence from Google's withdrawal

Internet search is an important channel through which retail investors gather and process information. This paper investigates whether limiting the retail investors' accessibility to the Internet could affect the incorporation of firm-specific information in prices, as measured by stock price synchronicity. Using Google's withdrawal of search services from China as an exogenous shock, I employ the matching-based difference-in-differences design and find an increase in synchronicity after Google's withdrawal, equivalent to a 4.6% growth in R2. Further analysis shows that the synchronicity measure arguably captures firm-specific information rather than noise. In addition, the improved synchronicity is concentrated in subsamples where firms' corporate disclosures are verbose and few, firms are geographically inaccessible, and the managerial entrenchment effect dominates the incentive alignment effect in corporate governance. The results are not driven by alternative explanations and are robust to alternative samples, alternative variable constructions, and the inclusion of more control variables.

The flight to safety during credit recovery: The role of implicit government guarantees

This paper examines the investor flight-to-safety phenomenon during the credit recovery period following corporate bond defaults. We find that implicit government guarantee (IGG) bonds crowd out non-implicit government guarantee (non-IGG) bonds in the Chinese corporate bond market at the provincial level. The crowding-out effect is stronger in a province with scarce bank credit resources. In contrast, the crowding-out effect disappears when the bonds are explicitly guaranteed by a third-party or if the default event is triggered by a state-owned enterprise (SOE). This finding is robust to various maturity terms, alternative samples, propensity score matching and placebo tests. Our evidence highlights the significant role of implicit government guarantees in the crowding-out effect during the credit recovery period.

Bio-efficacy of aluminum phosphide and cypermethrin against some physiological and biochemical aspects of Chrysomya megacephala maggots

Carrion flies play a significant role in forensic entomotoxicology, where they are employed as alternative samples when traditional samples are unavailable. In situations of poisoned death, these toxins disrupt insect development and affect forensic entomology analyses. So, forensic entomotoxicologists must be aware of this impact. The present study aimed to determine the effects of aluminum phosphide (AlP) and cypermethrin (CP) on the biochemical parameters and antioxidant enzymes of the third instar of Chrysomya megacephala maggots. C. megacephala was reared on normal and poisoned rabbit carcasses with aluminum phosphide and cypermethrin. The third larval instar of C. megacephala was studied using by spectrophotometer for detection of total protein, (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione s-transferase (GST), catalase (CAT) and malondialdehyde (MDA). The results indicated to significantly decrease of TP, TAC, SOD, GST and CAT and increase of AST, ALT and MDA in the maggots reared on the poisoned carcasses with AlP or CP compared with control group. In conclusion, the tested insecticides brought about a decrease antioxidant enzyme activity and increase of MDA could be involved in free radicals in C. megacephala larvae leading to oxidative stress by these insecticidal components.