Transforming food waste into animal feeds: an in-depth overview of conversion technologies and environmental benefits.

Food waste is a global concern, with significant quantities of edible food being discarded every day. However, innovative conversion technologies have emerged to effectively transform this waste into valuable animal feed. This review paper provides a comprehensive examination of the conversion technologies used to transform food waste into animal feed, along with an analysis of the environmental benefits associated with these processes. The paper delves into various conversion methods such as anaerobic digestion, insect-based conversion, and microbial fermentation along with exploring their mechanisms and suitability for converting food waste into valuable animal feed resources. Additionally, the environmental benefits, including waste reduction, greenhouse gas emission reduction, and resource conservation, are discussed in detail. The review highlights the potential of these technologies to address the pressing issue of food waste while contributing to a more sustainable and resource-efficient food system. The findings of this review emphasize the importance of adopting and further developing these conversion technologies as a means to mitigate environmental impacts, promote circular economy principles, and enhance the overall sustainability of the food and agriculture sector.

Spectroscopic investigations on fungal aspartic protease as target of gallic acid.

Proteases are a major virulence factor in pathogenic fungi and can serve as a potential therapeutic target. The interaction of gallic acid (GA) with Aspartic fungal protease (PepA) was investigated using biophysical and in silico approaches. UV-Vis and fluorescence spectroscopy showed complex formation and static quenching of PepA by GA with Ka of 7.4 × 105 M-1 and stoichiometric binding site (n) of 1.67. CD-spectroscopy showed marked changes in helical content and synchronous fluorescence spectra measurements indicated significant changes in the microenvironment around tryptophan residues in the GA-PepA complex. Outcomes of Isothermal Titration Calorimetry (ITC) measurement and molecular modelling studies validated the spectroscopic results. The binding of GA to Human Serum albumin (HSA) was moderate (Ka = 1.9 × 103 M-1) and did not cause structural disruption of HSA. To conclude, gallic acid is strongly bound to fungal protease leading to structural disruption and inhibition whereas HSA structure was largely conserved. Gallic acid thus appears to be a potential therapeutic agent against fungal proteases.

Autism spectrum disorder among 16- to 30-month-old children in Bangladesh: Observational cross-sectional study.

LAY ABSTRACT: A nationwide survey was done in Bangladesh to assess autism spectrum disorder prevalence in 16- to 30-month-old children at urban-rural distribution and to determine the association with socioeconomic and demographic conditions. A three-stage cluster sampling method was used where districts from all divisions were selected in the first stage, census enumeration areas as blocks of households were selected in the second stage and households (within the blocks) were selected in the third stage. Thereby, it included 38,440 children from 37,982 households (71% rural, 29% urban) aged 16-30 months from 30 districts of eight divisions of Bangladesh. Screening was done with a 'Red Flag' tool and Modified Checklist for Toddlers and a final diagnosis using Diagnostic and Statistical Manual of Mental Disorders, 5th Edition for autism spectrum disorder. Autism spectrum disorder prevalence was 17 per 10,000 young children - in other words, one in 589 young children. Boys were found at higher risk of autism (one in 423 boys; one in 1026 girls). Prevalence of autism spectrum disorder was higher in urban environments than in rural ones - 25/10,000 and 14/10,000, respectively. More autism spectrum disorder children were found in advanced age groups of parents, especially mothers, and in households with a higher wealth quintile. This survey is significant as it covers both urban and rural areas and specifically targets very young children. The involvement of the Bangladesh Bureau of Statistics, as well as support from the entire healthcare system infrastructure, makes this survey more representative on a national level. Its results will form a database to support the development of an effective early intervention programme in Bangladesh. We hope it will prove useful for researchers, clinicians and frontline healthcare workers, and inform the decisions of policymakers and funders in Bangladesh.

Applications of Phyto-Nanotechnology for the Treatment of Neurodegenerative Disorders.

The strategies involved in the development of therapeutics for neurodegenerative disorders are very complex and challenging due to the existence of the blood-brain barrier (BBB), a closely spaced network of blood vessels and endothelial cells that functions to prevent the entry of unwanted substances in the brain. The emergence and advancement of nanotechnology shows favourable prospects to overcome this phenomenon. Engineered nanoparticles conjugated with drug moieties and imaging agents that have dimensions between 1 and 100 nm could potentially be used to ensure enhanced efficacy, cellular uptake, specific transport, and delivery of specific molecules to the brain, owing to their modified physico-chemical features. The conjugates of nanoparticles and medicinal plants, or their components known as nano phytomedicine, have been gaining significance lately in the development of novel neuro-therapeutics owing to their natural abundance, promising targeted delivery to the brain, and lesser potential to show adverse effects. In the present review, the promising application, and recent trends of combined nanotechnology and phytomedicine for the treatment of neurological disorders (ND) as compared to conventional therapies, have been addressed. Nanotechnology-based efforts performed in bioinformatics for early diagnosis as well as futuristic precision medicine in ND have also been discussed in the context of computational approach.

A systematic review on distribution and antifungal resistance pattern of Candida species in the Indian population.

The emergence of antifungal drug resistance in Candida species has led to increased morbidity and mortality in immunocompromised patients. Understanding species distribution and antifungal drug resistance patterns is an essential step for novel drug development. A systematic review was performed addressing this challenge in India with keywords inclusive of 'Candida', 'Antifungal Drug Resistance', 'Candidemia', 'Candidiasis' and 'India'. A total of 106 studies (January 1978-March 2020) from 20 Indian states were included. Of over 11,429 isolates, Candida albicans was the major species accounting for 37.95% of total isolates followed by C. tropicalis (29.40%), C. glabrata (11.68%) and C. parapsilosis (8.36%). Rates of antifungal resistance were highest in non-albicans Candida (NAC) species - C. haemuloni (47.16%), C. krusei (28.99%), C. lipolytica (28.89%) and C. glabrata (20.69%). Approximately 10.34% isolates of C. albicans were observed to be drug resistant. Candida species were frequently resistant to certain azoles (ketoconazole-22.2%, miconazole-22.1% and fluconazole-21.8%). In conclusion, the present systematic review illustrates the overall distribution and antifungal resistance pattern of Candida species among the Indian population that could be helpful in the future for the formation of treatment recommendations for the region but also elsewhere. LAY SUMMARY: A total of 106 studies were reviewed to define the prevalence, distribution and antifungal resistance pattern of Candida species in India. The presented data could become the point of reference for all reported findings on Candida species in India.

Exploration of Fungal Lipase as Direct Target of Eugenol through Spectroscopic Techniques.

BACKGROUND: Fungal lipase dependent processes are important for their pathogenicity. Lipases can therefore be explored as direct target of promising herbal antifungals. OBJECTIVE: We explored Aspergillus niger lipase as a direct target of eugenol through spectroscopic techniques and compare results with Bovine Serum Albumin and lysozyme to comment on selectivity of eugenol towards lipase. METHODS: In vitro activity assays of lipase are used to determine concentration ranges. UV-Visible, Fluorescence and Circular dichroism spectroscopy were employed to determine binding constant, stoichiometric binding sites and structural changes in Lipase, BSA and lysozyme following incubation with varying concentrations of eugenol. RESULTS: In activity assays 50% inhibition of lipase was obtained at 0.913 mmoles/litre eugenol. UV-vis spectroscopy shows formation of lipase-eugenol, Bovine Serum Albumin-eugenol and lysozyme-eugenol complex well below this concentration of eugenol. Eugenol binding caused blue shift with Bovine Serum Albumin and lysozyme suggestive of compaction, and red shift with lipase. Negative ellipticity decreased with lipase but increased with Bovine Serum Albumineugenol and lysozyme-eugenol complexes suggesting loss of helical structure for lipase and compaction for Bovine Serum Albumin and lysozyme. Binding of eugenol to lipase was strong (Ka= 4.7 x 106 M-1) as compared to Bovine Serum Albumin and lysozyme. The number of stoichiometric eugenol binding sites on lipase was found to be 2 as compared to 1.37 (Bovine Serum Albumin) and 0.32 (lysozyme). Docking results also suggest strong binding of eugenol with lipase followed by Bovine Serum Albumin and lysozyme. CONCLUSION: Eugenol is found to be effective inhibitor and disruptor of secondary and tertiary structure of lipase, whereas its binding to Bovine Serum Albumin and lysozyme is found to be weak and less disruptive of structures suggesting selectivity of eugenol towards lipase.

PeMtb: A Database of MHC Antigenic Peptide of Mycobacterium tuberculosis.

BACKGROUND: For design of a subunit vaccine for tuberculosis, identification of antigenic Tcell epitope is of utmost importance. Several MHC prediction server are available that can accurately predict antigenic peptide of variable lengths. However, peptides predicted from one server not necessarily are predicted form another server, thus creating a confusing situation for scientists to choose a best epitope. METHOD: Keeping the above problem in mind, we developed a comprehensive database of peptides of Mycobacterial proteins. Each protein was taken from PubMed and was run through different MHC prediction servers, with the results being compiled into one database. RESULTS: For each protein, PeMtb generates a set of three different mers of variable lengths (12 mer or 13-mer) based on their ranking; with each mer being predicted for a plethora of MHC alleles. Researcher can choose the peptide (mers) that gives best binding affinity from most of the servers. CONCLUSION: The database relieves the investigators of the painstaking task of searching various MHC prediction servers for the right epitope (T-cell epitope) for a particular Mycobacterial antigen. We trust and anticipate that PeMtb will be a practical platform for trial and computational analyses of antigenic peptides for Mycobacterium tuberculosis. All the resources and information can be accessed by PeMtb home page www.pemtb-amu.org.

Deciphering the interactions between chlorambucil and calf thymus DNA: a multi-spectroscopic and molecular docking study.

Non-covalent interactions of chlorambucil with calf thymus DNA was investigated using multi-spectroscopic techniques and molecular docking study. Binding constant calculated was found to be 1.54×10(4)M(-1) at 290K, significantly lower than various known intercalators. Quenching process was found to be static as evident by biomolecular quenching constant. Thermodynamic parameters revealed the involvement of hydrophobic interactions and hydrogen bonds in the binding. Chlorambucil was found to interact via external binding mode and follow groove binding as it replaces Hoechst (a typical groove binder) from the groove of DNA but does not replace intercalating dyes including ethidium bromide and acridine orange from the DNA helix. These results were further supported by KI quenching experiments, DNA melting studies, CD spectroscopy and molecular docking.

Transfer of learned manipulation following changes in degrees of freedom.

The present study was designed to determine whether manipulation learned with a set of digits can be transferred to grips involving a different number of digits, and possible mechanisms underlying such transfer. The goal of the task was to exert a torque and vertical forces on a visually symmetrical object at object lift onset to balance the external torque caused by asymmetrical mass distribution. Subjects learned this manipulation through consecutive practice using one grip type (two or three digits), after which they performed the same task but with another grip type (e.g., after adding or removing one digit, respectively). Subjects were able to switch grip type without compromising the behavioral outcome (i.e., the direction, timing, and magnitude of the torque exerted on the object was unchanged), despite the use of significantly different digit force-position coordination patterns in the two grip types. Our results support the transfer of learning for anticipatory control of manipulation and indicate that the CNS forms an internal model of the manipulation task independent of the effectors that are used to learn it. We propose that sensory information about the new digit placement--resulting from adding or removing a digit immediately after the switch in grip type--plays an important role in the accurate modulation of new digit force distributions. We discuss our results in relation to studies of manipulation reporting lack of learning transfer and propose a theoretical framework that accounts for failure or success of motor learning generalization.

Association between chronic arsenic exposure and nutritional status among the women of child bearing age: a case-control study in Bangladesh.

The role of nutritional factors in arsenic metabolism and toxicity is yet to be fully elucidated. A low protein diet results in decreased excretion of DMA and increased tissue retention of arsenic in experimental studies. Malnourished women carry a higher risk of adverse pregnancy outcomes. Chronic exposure to high arsenic (>50 microg/L) through drinking water also increases the risk of adverse pregnancy outcomes. The synergistic effects (if any) of malnutrition and chronic arsenic exposure may worsen the adverse pregnancy outcomes. This population based case control study reports the association between chronic arsenic exposure and nutritional status among the rural women in Bangladesh. 348 cases (BMI < 18.5) and 360 controls (BMI 18.5-24.99) were recruited from a baseline survey conducted among 2,341 women. An excess risk for malnutrition was observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for potential confounders such as participant's age, religion, education, monthly household income and history of oral contraceptive pills. Women exposed to arsenic >50 microg/L were at 1.9 times (Odds Ratio = 1.9, 95% CI = 1.1-3.6) increased risk of malnutrition compared to unexposed. The findings of this study suggest that chronic arsenic exposure is likely to contribute to poor nutritional status among women of 20-45 years.

Prevalence and determinants of malnutrition among reproductive aged women of rural Bangladesh.

Malnutrition among the rural Bangladeshi women of reproductive age is still very high. This high prevalence attributes to a range of adverse health consequences on the women and their offspring. A total of 2341 women aged between 20 and 45 years residing in the study area were interviewed in this cross-sectional study. Information on socioeconomic variables, nutritional status, and pregnancy-related history was obtained using interviewer administered questionnaire. A total of 34% of the reproductive aged rural women suffer from malnutrition. A multivariate analysis shows association between malnutrition and monthly household income, history of taking oral contraceptive, current pregnancy status, and history of breastfeeding. The final regression model shows a statistically significant decreasing trend in malnutrition status with increasing income (P for trend <.001). The economic and health consequences of malnutrition in this group of women are enormous. National nutritional program should target this women group for any intervention with a special priority.

Kinetic and kinematic adaptation to anisotropic load.

Different investigators have proposed that multi-joint arm movements are planned with respect to either the path of the hand or the forces and torques acting about the moving joints. In this experiment, we examined the kinematic and kinetic response of the motor system when a load was applied to the forearm, which reduced the natural anisotropy of the arm. We asked two questions: (1) when the movement path changes upon the introduction of the novel load, do muscle torques at the shoulder and elbow remain the same as they were before the load was applied? and (2) when the path is restored partially as the novel load is learned, do changes in muscle torque occur preferentially at one or the other joint? Participants performed rapid arm movements to a target with and without the novel load attached to their arm. Changes in hand path and muscle torque profiles were examined immediately after the application of the load and again following 30 practice trials. The introduction of the load increased the curvature of hand paths for each participant and resulted in changes in the magnitude and time course of muscle torque at both joints, although to a greater extent at the shoulder. After practice with the load, hand paths and elbow muscle torques resembled those produced with no load. Muscle torques produced at the shoulder, however, did not return to pre-load patterns. These observations provide support for the idea that movements are initiated by planned muscle torques and that as the movement proceeds muscle torques are regulated in order to produce hand paths that conform approximately to a kinematic plan.

Resolving kinematic redundancy in target-reaching movements with and without external constraint.

In the context of target-reaching movements that involve the arms, trunk and legs, we have delineated rules for apportioning motions amongst body segments, which would be valid for a range of target locations that require forward bending. We further attempted to determine whether the rules are altered when motion is restricted at the knee, obliging a re-apportioning of segment motions. For each participant moving with unrestricted joints to nine target locations, principal component analysis of the changes in orientation (i.e., excursions) of six chosen segments revealed that their coupling can be described by two effective degrees of freedom (DoFs), whose weighted combinations account for the segmental excursions. Investigating the similarities and differences among individuals, we found that a set of two effective DoFs could account for the segment excursions among the group of participants who flex their knees significantly, and another set of two for the group who do not. Comparing the motions with and without the knee joints braced, we found that for each individual participant a set of two (or in some cases three) effective DoFs derived from the unrestricted segment excursions could account well for the altered segment excursions when the participant reached for the targets with the knees restricted. Our findings imply that the redundancy of kinematic DoFs can be resolved by reliance on a small number of couplings of segmental excursions, and, in light of the robustness of these couplings against mechanical restriction of joint motion, suggest a neural rather than mechanical origin for them.

The effect of movement direction on joint torque covariation.

It has been proposed that unconstrained upper limb movements are coordinated via a kinetic constraint that produces dynamic muscle torques at each moving joint that are a linear function of a single torque command. This constraint has been termed linear synergy (Gottlieb et al. J Neurophysiol 75:1760-1764, 1996). The current study tested two hypotheses: (1) that the extent of covariation between dynamic muscle torques at the shoulder and elbow varied with the direction of movement and (2) that the extent to which muscle torques deviated from linear synergy would be reproduced by a simulation of pointing movements in which the path of the hand was constrained to be straight. Dynamic muscle torques were calculated from sagittal plane pointing movements performed by 12 participants to targets in eight different directions. The results of principal component analyses performed on the muscle torque data demonstrated direction-dependent variation in the extent to which dynamic muscle torques covaried at the shoulder and elbow. Linear synergy was deviated from substantially in movement directions for which the magnitude of muscle torque was low at one joint. A simulation of movements with straight hand paths was able to accurately estimate the amount of covariation between muscle torques at the two joints in many directions. These results support the idea that a kinematic constraint is imposed by the central nervous system during unconstrained pointing movements. Linear synergy may also be applied as a coordinating constraint in circumstances where its application allows the path of the moving endpoint to remain close to a straight line.

Kinematic and kinetic constraints on arm, trunk, and leg segments in target-reaching movements.

We studied target reaching tasks involving not only the arms but also the trunk and legs, which necessitated some trunk flexion. Such tasks can be successfully completed using an infinite number of combinations of segment motions due to the inherent kinematic redundancy with the excessive degrees of freedom (DOFs). Sagittal plane motions of six segments (shank, thigh, pelvis, trunk, humerus, and forearm) and dynamic torques of six joints (ankle, knee, hip, lumbar, shoulder, and elbow) were analyzed separately by principal component (PC) analyses to determine if there was a commonality among the shapes of the respective waveforms. Additionally, PC analyses were used to probe for constraining relationships among the 1) relative magnitudes of segment excursions and 2) the peak-to-peak dynamic joint torques. In summary, at the kinematic level, the tasks are simplified by the use of a single common waveform for all segment excursions with 89.9% variance accounted for (VAF), but with less fixed relationships among the relative scaling of the magnitude of segment excursions (62.2% VAF). However, at the kinetic level, the time course of the dynamic joint torques are not well captured by a single waveform (72.7% VAF), but the tasks are simplified by relatively fixed relationships among the scaling of dynamic joint torque magnitudes across task conditions (94.7% VAF). Taken together, these results indicate that, while the effective DOFs in a multi-joint task are reduced differently at the kinematic and kinetic levels, they both contribute to simplifying the neural control of these tasks.

Chronic arsenic exposure and adverse pregnancy outcomes in bangladesh.

BACKGROUND: Chronic exposure to arsenic through drinking water has the potential to cause adverse pregnancy outcomes, although the association has not been demonstrated conclusively. This cross-sectional study assessed the association between arsenic in drinking water and spontaneous abortion, stillbirth, and neonatal death. METHODS: In this cross-sectional study, 533 women were interviewed. Information on sociodemographic characteristics, drinking water use, and adverse pregnancy outcomes was obtained through a structured pretested interviewer-administered questionnaire. The respondents reported use of a total of 223 tube wells; for 208 wells, water samples were measured using an ultraviolet/visible spectrophotometry method, whereas 15 were measured by flow-injection hydride generation atomic absorption spectrometry (FIHG-AAS). RESULTS: Excess risks for spontaneous abortion and stillbirth were observed among the participants chronically exposed to higher concentrations of arsenic in drinking water after adjusting for participant's height, history of hypertension and diabetes, and (for neonatal death only) age at first pregnancy. Comparing exposure to arsenic concentration of greater than 50 microg/L with 50 microg/L or less, the odds ratios were 2.5 (95% confidence interval=1.5-4.3) for spontaneous abortion, 2.5 (1.3-4.9) for stillbirth, and 1.8 (0.9-3.6) for neonatal death. CONCLUSIONS: These study findings suggest that chronic arsenic exposure may increase the risk of fetal and infant death.

Association between nutritional status and arsenicosis due to chronic arsenic exposure in Bangladesh.

The role of nutritional factors in arsenic metabolism and toxicity is not clear. Provision of certain low protein diets resulted in decreased excretion of DMA and increased tissue retention of arsenic in experimental studies. This paper reports a prevalence comparison study conducted in Bangladesh to assess the nutritional status among the chronic arsenic exposed and unexposed population. 138 exposed individuals diagnosed as arsenicosis patients were selected from three known arsenic endemic villages of Bangladesh and age, sex matched 144 unexposed subjects were randomly selected from three arsenic free villages. The mean arsenic concentration in drinking water for the exposed and unexposed population was 641.15 and 13.5 microg L(-1) respectively. Body Mass Index was found to be lower than 18.5, the cut off point for malnutrition, in 57 (41.31%) out of 138 exposed arsenicosis cases and 31 (21.53%) out of 144 unexposed individuals. The crude prevalence ratio (or risk) was 1.92 (95% CI = 1.33-2.78) for poor nutritional status among the arsenicosis cases compared to the unexposed population. The findings of this study add to the evidence that poor nutritional status may increase an individual's susceptibility to chronic arsenic toxicity, or alternatively that arsenicosis may contribute to poor nutritional status.

Non-cancer effects of chronic arsenicosis in Bangladesh: preliminary results.

A total of 136 patients were studied in three Upazillas of Laxmipur, Barisal and Madaripur districts were selected for health awareness campaign program. According to the existing data, these villages were ranked as high exposure. Demographic data of the patients investigated are showing pigmentation was seen in all--136 cases, keratosis was found only in 110 cases, and skin ulcer was detected in 13 cases. The predominant features are indicating respiratory sign and symptoms followed by conjunctival congestion and redness of eyes. Weakness was predominant symptom, and all most all cases reported weakness. There were few smokers (n = 16) and analyses were confined to non-smokers (n = 94). A total of the 94 subjects participated in this study. The sex ratio was 1:1.3 (male vs. female). The relative risk of chronic cough increased with age (RR=2.12, for 26-50 age group; RR=2.30 for age group more than 51) reflecting chronic exposure, but the 95% confidence intervals included unity. The relative risk of chronic bronchitis increased with age (RR=2.68, for 26-50 age group; RR=2.30 for age group more than 51) reflecting chronic exposure, but the 95% confidence intervals also included unity. The findings presented here provide evidence that ingestion of inorganic arsenic in drinking water may results in increases risk of chronic cough and bronchitis.

Effect of movement speed on limb segment motions for reaching from a standing position.

The performance of a standing reaching task that necessitates some forward bending requires: (1) the coordination of multiple joints (i.e., the trunk and limb segments) to reach the target, and (2) the preservation of postural stability. It has been proposed that the neural control of multijoint reaching tasks can be simplified by time scaling of joint motions while keeping joint excursions the same. To determine if time scaling of joint motions was used in this more complex reaching task, we had 20 healthy subjects (10 male and 10 female) reach for two targets located in a parasagittal plane while standing on a force platform. Subjects reached for the targets at a comfortable speed and a fast paced speed. Sagittal plane motions of the right shank, thigh, pelvis, trunk, humerus, and forearm were measured. At the fast paced movement speeds subjects had significantly larger excursions of the thigh, pelvis, humerus, and forearm compared to the comfortable speed. Thus, segment motions are not simply time scaled for standing multijoint reaches. We explored three possible reasons for not obeying time scaling: (1) to reduce scaling of peak kinetic energy, (2) to reduce scaling of peak horizontal ground reaction force, and (3) a convergence of movement strategies at faster speeds. While subjects modified their movement strategy in relationship to movement speed, these changes had no significant effect on the expected scaling of peak kinetic energy, or peak horizontal ground reaction forces. Given the intersubject differences in movement strategies used to perform these reaching tasks at the fast speeds, a convergence of movement strategies was ruled out. We propose that the increase in segment motions with speed may be a consequence of rules underlying motor output, the increases being greater for segments in which viscoelastic resistance to movement is more significant compared to inertial resistance.

Circle-drawing movements at different speeds: role of inertial anisotropy.

This study investigated the role of inertial anisotropy at the hand in causing distortions in movement. Subjects drew circles in the horizontal plane at four locations in the workspace at three instructed paces using elbow and shoulder movements. Specifically, we tested two hypotheses, which we would expect if the anisotropy of inertia were not completely accounted for by the CNS when generating circle-drawing movements: 1) speed will affect the circularity of figures, with faster movements associated with greater elongation into an oval shape, irrespective of workspace location for configurations with a similar angle between the forearm and upper arm. 2) The elongation of the circle at fast speeds will be in the direction of least inertia. The results showed that despite individual differences in the speed dependence of the relative motions at the elbow and the shoulder, the circularity decreased (distortion increased) with increased speed, and workspace location had no effect on circularity. We also found that the elongation of the circles at fast speeds was in a direction close to but significantly different from the direction of least inertia for three workspace locations and was in the direction of least inertia for the fourth location. We suggest that the elongation results from lack of full accounting by the CNS of the anisotropy of viscosity and inertia.