Simulating short-term light responses of photosynthesis and water use efficiency in sweet sorghum under varying temperature and CO2 conditions.

Climate change, characterized by rising atmospheric CO2 levels and temperatures, poses significant challenges to global crop production. Sweet sorghum, a prominent C4 cereal extensively grown in arid areas, emerges as a promising candidate for sustainable bioenergy production. This study investigated the responses of photosynthesis and leaf-scale water use efficiency (WUE) to varying light intensity (I) in sweet sorghum under different temperature and CO2 conditions. Comparative analyses were conducted between the A n-I, g s-I, T r-I, WUEi-I, and WUEinst-I models proposed by Ye et al. and the widely utilized the non-rectangular hyperbolic (NRH) model for fitting light response curves. The Ye's models effectively replicated the light response curves of sweet sorghum, accurately capturing the diminishing intrinsic WUE (WUEi) and instantaneous WUE (WUEinst) trends with increasing I. The fitted maximum values of A n, g s, T r, WUEi, and WUEinst and their saturation light intensities closely matched observations, unlike the NRH model. Despite the NRH model demonstrating high R 2 values for A n-I, g s-I, and T r-I modelling, it returned the maximum values significantly deviating from observed values and failed to generate saturation light intensities. It also inadequately represented WUE responses to I, overestimating WUE. Across different leaf temperatures, A n, g s, and T r of sweet sorghum displayed comparable light response patterns. Elevated temperatures increased maximum A n, g s, and T r but consistently declined maximum WUEi and WUEinst. However, WUEinst declined more sharply due to the disproportionate transpiration increase over carbon assimilation. Critically, sweet sorghum A n saturated at current atmospheric CO2 levels, with no significant gains under 550 µmol mol-1. Instead, stomatal closure enhanced WUE under elevated CO2 by coordinated g s and T r reductions rather than improved carbon assimilation. Nonetheless, this response diminished under simultaneously high temperature, suggesting intricate interplay between CO2 and temperature in modulating plant responses. These findings provide valuable insights into photosynthetic dynamics of sweet sorghum, aiding predictions of yield and optimization of cultivation practices. Moreover, our methodology serves as a valuable reference for evaluating leaf photosynthesis and WUE dynamics in diverse plant species.

Addressing the long-standing limitations of double exponential and non-rectangular hyperbolic models in quantifying light-response of electron transport rates in different photosynthetic organisms under various conditions.

The models used to describe the light response of electron transport rate in photosynthesis play a crucial role in determining two key parameters i.e., the maximum electron transport rate (J max) and the saturation light intensity (I sat). However, not all models accurately fit J-I curves, and determine the values of J max and I sat. Here, three models, namely the double exponential (DE) model, the non-rectangular hyperbolic (NRH) model, and a mechanistic model developed by one of the coauthors (Z-P Ye) and his coworkers (referred to as the mechanistic model), were compared in terms of their ability to fit J-I curves and estimate J max and I sat. Here, we apply these three models to a series of previously collected Chl a fluorescence data from seven photosynthetic organisms, grown under different conditions. Our results show that the mechanistic model performed well in describing the J-I curves, regardless of whether photoinhibition/dynamic down-regulation of photosystem II (PSII) occurs. Moreover, both J max and I sat estimated by this model are in very good agreement with the measured data. On the contrary, although the DE model simulates quite well the J-I curve for the species studied, it significantly overestimates both the J max of Amaranthus hypochondriacus and the I sat of Microcystis aeruginosa grown under NH4 +-N supply. More importantly, the light intensity required to achieve the potential maximum of J (J s) estimated by this model exceeds the unexpected high value of 105 µmol photons m-2 s-1 for Triticum aestivum and A. hypochondriacus. The NRH model fails to characterize the J-I curves with dynamic down-regulation/photoinhibition for Abies alba, Oryza sativa and M. aeruginosa. In addition, this model also significantly overestimates the values of J max for T. aestivum at 21% O2 and A. hypochondriacus grown under normal condition, and significantly underestimates the values of J max for M. aeruginosa grown under NO3 -N supply. Our study provides evidence that the 'mechanistic model' is much more suitable than both the DE and NRH models in fitting the J-I curves and in estimating the photosynthetic parameters. This is a powerful tool for studying light harvesting properties and the dynamic down-regulation of PSII/photoinhibition.

A review on light response model of photosynthesis under different environmental conditions.

Light response curve of photosynthesis (An-I curve) is a useful modeling tool to investigate how photosynthesis reacts with different abiotic factors, which would help quantify the response of photosynthetic rate to photosynthetically active radiation. Based on the mathematical characteristics of photosynthesis An-I models, we reviewed the advantages of using these model in practice and the potential caveats. We proposed the development of new mechanistic photosynthesis An-I models based on the primary light response and discussed its advantages in the field of plant ecology and physiology. Photosynthesis has three main steps, including the primary reaction, the assimilatory power forms, and the carbon assimilation. Changes in each step could directly affect the photochemical efficiency and carbon assimilation in photosynthesis. The primary reaction consists of a series of physical processes that are related to light energy absorption and utilization, including the absorption of light energy, the change of quantum state, and the transfer and de-excitation of exciton resonance of light-trapping pigment molecules. How-ever, the empirical photosynthesis An-I models can not explain some scenarios. For example, the non-photochemical quenching in plants increases with increasing light intensity in a non-linear manner. Further, the life-time of singlet chlorophyll molecules can be extended when plant light-harvesting pigment molecules absorb excessive light energy but would not be immediately used for the photochemical reaction. Meanwhile, the parameters obtained by fitting the mechanistic An-I curve model can not only reflect the primary photochemical reaction characteristics of plants, but also describe the physical characteristics of plant light harvesting pigment molecules, such as the number of light harvesting pigment molecules in the excited state (Nk) and effective light energy absorption cross-section (σik'). This can be used to further investigate the physical characteristics of light harvesting pigment molecules, including the light-response of Nk and σik' and the average life time of light harvesting pigment molecules in the lowest exciting state (τmin). In addition, it would be necessary to determine how to incorporate abiotic factors, such as temperature and CO2 concentration, into the mechanistic An-I curve model, as well as to determine the association between the abiotic factors and light harvesting pigment molecules, such as Nk, σik', and τmin.

Investigation on absorption cross-section of photosynthetic pigment molecules based on a mechanistic model of the photosynthetic electron flow-light response in C3, C4 species and cyanobacteria grown under various conditions.

Investigation on intrinsic properties of photosynthetic pigment molecules participating in solar energy absorption and excitation, especially their eigen-absorption cross-section (σ ik) and effective absorption cross-section (σ ' ik), is important to understand photosynthesis. Here, we present the development and application of a new method to determine these parameters, based on a mechanistic model of the photosynthetic electron flow-light response. The analysis with our method of a series of previously collected chlorophyll a fluorescence data shows that the absorption cross-section of photosynthetic pigment molecules has different values of approximately 10-21 m2, for several photosynthetic organisms grown under various conditions: (1) the conifer Abies alba Mill., grown under high light or low light; (2) Taxus baccata L., grown under fertilization or non-fertilization conditions; (3) Glycine max L. (Merr.), grown under a CO2 concentration of 400 or 600 µmol CO2 mol-1 in a leaf chamber under shaded conditions; (4) Zea mays L., at temperatures of 30°C or 35°C in a leaf chamber; (5) Osmanthus fragrans Loureiro, with shaded-leaf or sun-leaf; and (6) the cyanobacterium Microcystis aeruginosa FACHB905, grown under two different nitrogen supplies. Our results show that σ ik has the same order of magnitude (approximately 10-21 m2), and σ ' ik for these species decreases with increasing light intensity, demonstrating the operation of a key regulatory mechanism to reduce solar absorption and avoid high light damage. Moreover, compared with other approaches, both σ ik and σ ' ik can be more easily estimated by our method, even under various growth conditions (e.g., different light environment; different CO2, NO2, O2, and O3 concentrations; air temperatures; or water stress), regardless of the type of the sample (e.g., dilute or concentrated cell suspensions or leaves). Our results also show that CO2 concentration and temperature have little effect on σ ik values for G. max and Z. mays. Consequently, our approach provides a powerful tool to investigate light energy absorption of photosynthetic pigment molecules and gives us new information on how plants and cyanobacteria modify their light-harvesting properties under different stress conditions.

Modeling Light Response of Electron Transport Rate and Its Allocation for Ribulose Biphosphate Carboxylation and Oxygenation.

Accurately describing the light response curve of electron transport rate (J-I curve) and allocation of electron flow for ribulose biphosphate (RuBP) carboxylation (J C-I curve) and that for oxygenation (J O-I curve) is fundamental for modeling of light relations of electron flow at the whole-plant and ecosystem scales. The non-rectangular hyperbolic model (hereafter, NH model) has been widely used to characterize light response of net photosynthesis rate (A n; A n-I curve) and J-I curve. However, NH model has been reported to overestimate the maximum A n (A nmax) and the maximum J (J max), largely due to its asymptotic function. Meanwhile, few efforts have been delivered for describing J C-I and J O-I curves. The long-standing challenge on describing A n-I and J-I curves have been resolved by a recently developed A n-I and J-I models (hereafter, Ye model), which adopt a nonasymptotic function. To test whether Ye model can resolve the challenge of NH model in reproducing J-I, J C-I and J O-I curves over light-limited, light-saturated, and photoinhibitory I levels, we compared the performances of Ye model and NH model against measurements on two C3 crops (Triticum aestivum L. and Glycine max L.) grown in field. The results showed that NH model significantly overestimated the A nmax and J max for both species, which can be accurately obtained by Ye model. Furthermore, NH model significantly overestimated the maximum electron flow for carboxylation (J C-max) but not the maximum electron flow for oxygenation (J O-max) for both species, disclosing the reason underlying the long-standing problem of NH model-overestimation of J max and A nmax.

Involvement of NADPH oxidase isoforms in the production of O2- manipulated by ABA in the senescing leaves of early-senescence-leaf (esl) mutant rice (Oryza sativa).

In this study, the differences in reactive oxygen species (ROS) generation and abscisic acid (ABA) accumulation in senescing leaves were investigated by early-senescence-leaf (esl) mutant and its wild type, to clarify the relationship among ABA levels, ROS generation, and NADPH oxidase (Nox) in senescing leaves of rice (Oryza sativa). The temporal expression levels of OsNox isoforms in senescing leaves and their expression patterns in response to ABA treatment were determined through quantitative real-time reverse transcription PCR (qRT-PCR). Results showed that the flag leaf of the esl mutant generated more O2- concentrations and accumulated higher ABA levels than the wild-type cultivar did in the grain-filling stage. Exogenous ABA treatment induced O2- generation; however, it was depressed by diphenyleneiodonium chloride (DPI) pretreatment in the detached leaf segments. This finding suggested the involvement of NADPH oxidase in ABA-induced O2- generation. The esl mutant exhibited significantly higher expression of OsNox2, OsNox5, OsNox6, and OsNox7 in the initial of grain-filling stage, followed by sharply decrease. The transcriptional levels of OsNox1, OsNox3, and OsFR07 in the flag leaf of the esl mutant were significantly lower than those in the wild-type cultivar. The expression levels of OsNox2, OsNox5, OsNox6, and OsNox7 were significantly enhanced by exogenous ABA treatments. The enhanced expression levels of OsNox2 and OsNox6 were dependent on the duration of ABA treatment. The inducible expression levels of OsNox5 and OsNox7 were dependent on ABA concentrations. By contrast, exogenous ABA treatment severely repressed the transcripts of OsNox1, OsNox3, and OsFR07 in the detached leaf segments. Therefore, OsNox2, OsNox5, OsNox6, and OsNox7 were probably involved in the ABA-induced O2- generation in the initial stage of leaf senescence. Subsequently, other oxidases activated in deteriorating cells were associated with ROS generation and accumulation in the senescing leaves of the esl mutant. Conversely, OsNox1, OsNox3, and OsFR07 were not associated with ABA-induced O2- generation during leaf senescence.

Senescence-specific change in ROS scavenging enzyme activities and regulation of various SOD isozymes to ROS levels in psf mutant rice leaves.

To clarify the interaction between different antioxidant enzymes for monitoring oxidative stress and ROS burst in rice senescent leaves, we investigated the genotype-dependent alteration in temporal patterns of the O2•- production rate, H2O2 content, and ROS-scavenging enzyme activities during leaf senescence in two rice genotypes, namely, the premature senescence of flag leaf (psf) mutant and its wild type. Results showed that the psf mutant differed obviously from its wild type in leaf O2•- generation rate and H2O2 content accumulation, and the decreased activities of SOD, CAT, and APX in the psf leaves were strongly responsible for the increased ROS level and the accelerated leaf senescence. By contrast, the increase in POD activity was positively correlated with the senescence-related enhancement in O2•- generation in rice leaves. Among various SOD isoforms, Mn-SOD responded sensitively to the increasing O2•- generation rate, whereas Cu/Zn-SOD remained stable with the progression of leaf senescence. These findings suggest that the senescence-related decline in total SOD activity was mostly attributable to the downregulation of both the translation and transcription of Mn-SOD isoform. This occurrence finally resulted in the collapse of SOD defense system and accelerated leaf senescence for the psf mutant. Furthermore, we presented the possible contribution of several Cu/Zn-SOD expression patterns to the senescence-related O2•- detoxification in different cell compartments.

Involvement of Abscisic Acid in PSII Photodamage and D1 Protein Turnover for Light-Induced Premature Senescence of Rice Flag Leaves.

D1 protein in the PSII reaction center is the major target of photodamage, and it exhibits the highest turnover rate among all the thylakoid proteins. In this paper, rice psf (premature senescence of flag leaves) mutant and its wild type were used to investigate the genotype-dependent alteration in PSII photo-damage and D1 protein turnover during leaf senescence and its relation to ABA accumulation in senescent leaves. The symptom and extent of leaf senescence of the psf mutant appeared to be sunlight-dependent under natural field condition. The psf also displayed significantly higher levels of ABA accumulation in senescent leaves than the wild type. However, the premature senescence lesion of psf leaves could be alleviated by shaded treatment, concomitantly with the strikingly suppressed ABA level in the shaded areas of flag leaves. The change in ABA concentration contributed to the regulation of shade-delayed leaf senescence. The participation of ABA in the timing of senescence initiation and in the subsequent rate of leaf senescence was closely associated with PSII photodamage and D1 protein turnover during leaf senescence, in which the transcriptional expression of several key genes (psbA, psbB, psbC and OsFtsH2) involved in D1 protein biosynthesis and PSII repair cycle was seriously suppressed by the significantly increased ABA level. This response resulted in the low rate of D1 protein synthesis and impaired repair recovery in the presence of ABA. The psf showed evidently decreased D1 protein amount in the senescent leaves. Both the inhibition of de novo synthesized D1 protein and the slow rate of proteolytic removal for the photodamaged D1 protein was among the most crucial steps for the linkage between light-dependent leaf senescence and the varying ABA concentration in psf mutant leaves. OsFtsH2 transcriptional expression possibly played an important role in the regulation of D1 protein turnover and PSII repair cycle in relation to ABA mediated leaf senescence.

[Integration and demonstration of key techniques in surveillance and forecast of schistosomiasis in Jiangsu Province III Development of a machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding].

OBJECTIVE: To develop a machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding and to evaluate its effectiveness of field application, so as to provide a novel Oncomelania hupensis snail control technique in the large-scale marshlands. METHODS: The machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding, which was suitable for use in complex marshland areas, was developed according to the mechanization and automation principles, and was used for O. hupensis snail control in the marshland. The effect of the machine on environmental cleaning and plough was evaluated, and the distribution of living snails was observed at various soil layers following plough. The snail control effects of plough alone and plough followed by mollusciciding were compared. RESULTS: The machine could simultaneously complete the procedures of getting vegetation down and cut vegetation into pieces, plough and snail control by spraying niclosamide. After plough, the constituent ratios of living snails were 36.31%, 25.60%, 22.62% and 15.48% in the soil layers at depths of 0-5, 6-10, 11-15 cm and 16-20 cm respectively, and 61.91% living snails were found in the 0-10 cm soil layers. Seven and fifteen days after the experiment, the mortality rates of snails were 9.38% and 8.29% in the plough alone group, and 63.04% and 80.70% in the plough + mollusciciding group respectively (χ²7 d = 42.74, χ²15 d = 155.56, both P values < 0.01). Thirty days after the experiment, the densities of snails were 3.02 snails/0.1 m² and 0.53 snails/ 0.1 m² in the soil surface of the plough alone group and the plough + mollusciciding group, which decreased by 64.92% and 93.60%, respectively, and the decrease rate of snail density was approximately 30% higher in the plough + mollusciciding group than that in the plough alone group. CONCLUSIONS: The machine simultaneously integrating mechanized environmental cleaning and automatic mollusciciding achieves the integration of mechanical environmental cleaning and automatic niclosamide spraying in the complex marshland areas, which provides a novel technique of field snail control in the large-scale setting in China.

Transcriptional profile of genes involved in ascorbate glutathione cycle in senescing leaves for an early senescence leaf (esl) rice mutant.

To clarify the complex relationship between ascorbate-glutathione (AsA-GSH) cycle and H2O2-induced leaf senescence, the genotype-dependent difference in some senescence-related physiological parameters and the transcript levels and the temporal patterns of genes involved in the AsA-GSH cycle during leaf senescence were investigated using two rice genotypes, namely, the early senescence leaf (esl) mutant and its wild type. Meanwhile, the triggering effect of exogenous H2O2 on the expression of OsAPX genes was examined using detached leaves. The results showed that the esl mutant had higher H2O2 level than its wild type at the initial stage of leaf senescence. At transcriptional level, the association of expression of various genes involved in the AsA-GSH cycle with leaf senescence was isoform dependent. For OsAPXs, the transcripts of two cytosolic OsAPX genes (OsAPX1 and OsAPX2), thylakoid-bound OsAPX8, chloroplastic OsAPX7 and peroxisomal OsAPX4 exhibited remarkable genotype-dependent variation in their expression levels and temporal patterns during leaf senescence, there were significantly increasing transcripts of OsAXP1 and OsAPX7, severely repressed transcripts of OsAPX4 and OsAPX8 for the esl rice at the initial leaf senescence. In contrast, the repressing transcript of OsAPX8 was highly sensitive to the increasing H2O2 level in the senescing rice leaves, while higher H2O2 concentration resulted in the enhancing transcripts of two cytosolic OsAPX genes, OsAPX7 transcript was greatly variable with different H2O2 concentrations and incubating duration, suggesting that the different OsAPXs isoforms played a complementary role in perceiving and scavenging H2O2 accumulation at various H2O2 concentrations during leaf senescence. Higher H2O2 level, increased AsA level, higher activities of APX and glutathione reductase (GR), and relatively stable GSH content during the entire sampling period in the leaves of esl mutant implied that a close interrelationship existed between AsA level and APX activity in the ongoing senescence of rice leaves. The GSH supply in rice leaves was not the limiting factor for the efficient maintenance of AsA-GSH cycle, despite the senescence-related change in GR activity between the two rice genotypes.

[Integration and demonstration of key techniques in the surveillance and forecast of schistosomiasis in Jiangsu Province II Molluscicidal effect of 5% niclosamide ethanolamine granules in large-scale settings].

OBJECTIVE: To evaluate the field molluscicidal effect of 5% niclosamide ethanolamine granules, so as to provide a novel Oncomelania hupensis snail control approach for emergency treatment of high-risk settings. METHODS: Snail control tests with spraying of 5% niclosamide ethanolamine granules were conducted in two settings of 2 counties, and the dose-, time- and setting-specific field molluscicidal effects were tested. RESULTS: In the small-scale setting, spraying of 5% niclosamide ethanolamine granules at doses of 30, 40 and 50 g/m2 resulted in 54.55%, 68.41% and 73.45% 1-day snail mortality, 57.27%, 68.59% and 80.28% 3-day snail mortality, and 63.49%, 77.58% and 85.55% 7-day snail mortality, respectively, and no significant differences were detected in 1- and 3-day snail mortality caused by spraying of 5% niclosamide ethanolamine granules at doses of 30 and 40 g/m2 (all P > 0.05), while significant difference was found in the 7-day snail mortality (χ2 = 4.549, P < 0.05). In addition, spraying of 5% niclosamide ethanolamine granules at doses of 40 and 50 g/m2 resulted in comparable 1-, 3- and 7-day snail mortality (all P > 0.05). In the large-scale setting, spraying of 5% niclosamide ethanolamine granules at a dose of 40 g/m2 resulted in 85.29% and 87.70% 3-day snail mortality, 83.89% and 91.02% 7-day snail mortality, and 83.41% and 91.84% 15-day snail mortality in the environment-cleaning group and non-cleaning group, respectively. The overall snail mortality was 90.02% in the environment-cleaning group 3 to 15 days after spraying, which was significantly higher than that (84.28%) in the non-cleaning group (χ2 = 9.950, P < 0.05). After 15 days of spraying with 5% niclosamide ethanolamine granules at a dose of 40 g/m2, the densities of living snails reduced from 19.90 and 19.83 snails/0.1 m2 to 0.60 and 2.60 snails/0.1 m2 in the environment-cleaning group and non-cleaning group, with 96.98% and 86.89% reductions, respectively. CONCLUSION: The appropriate dose of 5% niclosamide ethanolamine granules is 40 g/m2 for snail control in the field, and environment cleaning of vegetation with a height of more than 50 cm may improve the molluscicidal efficacy.

Positional variation in grain mineral nutrients within a rice panicle and its relation to phytic acid concentration.

Six japonica rice genotypes, differing in panicle type, grain density, and phytic acid (PA) content, were applied to investigate the effect of grain position on the concentrations of major mineral nutrients and its relation to PA content and grain weight within a panicle. Grain position significantly affected the concentrations of the studied minerals in both the vertical and horizontal axes of a rice panicle. Heavy-weight grains, located on primary rachis and top rachis, generally had higher mineral concentrations, but were lower in PA concentration and molar ratios of PA/Zn, compared with the small-weight grains located on secondary rachis and bottom rachis, regardless of rice genotypes. However, on the basis of six rice genotypes, no significant correlations were found among mineral elements, PA, and grain weight. These results suggested that some desired minerals, like Zn and Fe, and their bioavailability, can be enhanced simultaneously by the modification of panicle patterns, and it will be helpful in the selection of rice genotypes with low PA and high mineral nutrients for further breeding strategy without sacrificing their high yields.

[Evaluation of effect of prevention and control system for imported falciparum malaria in Hanjiang District].

OBJECTIVE: To analyze the current situation of the comprehensive prevention and control system for imported falciparum malaria in Hanjiang District and evaluate its effect. METHODS: According to the Management Scheme on Control of Imported Falciparum Malaria in Yangzhou City, the comprehensive prevention and control system for imported falciparum malaria was implemented, and the relevant malaria data were collected and analyzed statistically. The data included plasmodium blood test ratio of fever patients among exported labors and those returned, the ratio of laboratory-confirmed cases among all reported cases of falciparum malaria, the ratio of falciparum malaria patients who received the standard treatment within 24 hours after onset, etc from 2010 to 2012. RESULTS: After the implementation of the comprehensive prevention and control system, the confirmation ratio of falciparum malaria cases within 24 hours following first visit has reached 60.47%, the average time from first visit to confirmation has shortened to 1.8 d, and the average time from onset to confirmation has shortened to 3.7 d. The health education coverage ratio was 100%, the health knowledge awareness ratio was 95.56%, the ratio of patients seeking treatment on own initiative was 100%, the laboratory-confirmed ratio was 100%, and the ratio of standard treatment after malaria diagnosis was 100%. CONCLUSION: The comprehensive prevention and control system carried out by Hanjiang District has made remarkable achievements.

[Establishment and application of imported falciparum malaria control system in Yangzhou City].

To aim at the characteristics of epidemic situation that the imported falciparum malaria cases increased year by year in Yangzhou City, an imported falciparum malaria control system was established. This control system was based on enhancing the management of returned labor service export persons from falciparum malaria endemic areas, the active medical remind service, the diagnostic capability and health education, and the cooperation of medical personnel and patients, and also avoiding diagnosis delay and misdiagnosis and promoting the treatment in time so as to decrease the serious patients and prevent them from death. After the application of the control system, there were 164 imported falciparum malaria cases from the returned persons of labor service export. The time from the attack of the disease to the diagnosis confirmed decreased from 6.8 days before the application of the system to 2.7 days after the application, and the rate of serious patients was 1.8% and there were no death cases.

[Surveillance of schistosomiasis in Yanjiang Village, Hanjiang District, 2005-2010].

The endemic situation of schistosomiasis and Oncomelania snail status in Yanjiang Village, Hanjiang District decreased significantly from 2005 to 2010. However, the surveillance in key population such as fishmen and boatmen still needs to be strengthened.