DeepGSEA: explainable deep gene set enrichment analysis for single-cell transcriptomic data.

MOTIVATION: Gene set enrichment (GSE) analysis allows for an interpretation of gene expression through pre-defined gene set databases and is a critical step in understanding different phenotypes. With the rapid development of single-cell RNA sequencing (scRNA-seq) technology, GSE analysis can be performed on fine-grained gene expression data to gain a nuanced understanding of phenotypes of interest. However, with the cellular heterogeneity in single-cell gene profiles, current statistical GSE analysis methods sometimes fail to identify enriched gene sets. Meanwhile, deep learning has gained traction in applications like clustering and trajectory inference in single-cell studies due to its prowess in capturing complex data patterns. However, its use in GSE analysis remains limited, due to interpretability challenges. RESULTS: In this paper, we present DeepGSEA, an explainable deep gene set enrichment analysis approach which leverages the expressiveness of interpretable, prototype-based neural networks to provide an in-depth analysis of GSE. DeepGSEA learns the ability to capture GSE information through our designed classification tasks, and significance tests can be performed on each gene set, enabling the identification of enriched sets. The underlying distribution of a gene set learned by DeepGSEA can be explicitly visualized using the encoded cell and cellular prototype embeddings. We demonstrate the performance of DeepGSEA over commonly used GSE analysis methods by examining their sensitivity and specificity with four simulation studies. In addition, we test our model on three real scRNA-seq datasets and illustrate the interpretability of DeepGSEA by showing how its results can be explained. AVAILABILITY AND IMPLEMENTATION: https://github.com/Teddy-XiongGZ/DeepGSEA.

Which individual components of a colorectal surgery enhanced recovery program are associated with improved surgical outcomes?

BACKGROUND: Enhanced recovery programs improve surgical outcomes. However, the association of adherence to individual components and outcomes in a comprehensive enhanced recovery program remains unclear. METHODS: We performed a retrospective study of all elective colorectal surgery patients at our institution from 2019 to 2022 (n = 1,175). Data were acquired from our institution's enhanced recovery program dashboard and American College of Surgeons National Surgical Quality Improvement Program database. Traditional analyses and machine-learning classification trees were used to identify enhanced recovery program components associated with length of stay, readmissions, and complication rates. RESULTS: The average length of stay was 5.0 days, readmission rate was 12.3%, and complication rate was 32.6%. On linear regression analysis, adherence to preoperative education, regional analgesia, pre- and postoperative multimodal analgesia, no nasogastric tube, early mobilization, early regular diet, early discontinuation of maintenance intravenous fluids, postoperative venous thromboembolism prophylaxis, and early Foley catheter removal were associated with an decrease in length of stay by 0.7-7.1 days (P < .05). Patients who adhered to no prolonged fasting had a 4.1% decrease in readmission rate (P = .04). Patients who adhered to no nasogastric tube, early mobilization, early regular diet, postoperative multimodal analgesia, and discontinuation of maintenance intravenous fluids had decreases in complication rates ranging from 7.0 to 28.2% (P < .001). Machine learning demonstrated that no nasogastric tube and discontinuation of maintenance intravenous fluids were significant predictors of shorter length of stay and no nasogastric tube and early mobilization were significant predictors of reduced complication rates. CONCLUSIONS: Although multiple components were associated outcomes, no nasogastric tube, early mobilization, early regular diet, postoperative multimodal analgesia, and early discontinuation of maintenance intravenous fluids were associated with more than 1 outcome. Focusing on these components may make enhanced recovery program implementation more feasible for resource-limited hospitals.

Beetroot in deep waters: Navigating the risks of supplement-induced blackouts in aquatic training.

Beetroot powder, a popular athletic supplement high in nitrates, purportedly enhances exercise performance. However, recent incidents during breath-hold swims in Air Force Special Warfare training, associated with beetroot powder use, raise safety concerns. Two cases of hypoxic events prompt discussion on interactions between beetroot supplementation and cardiovascular responses to breath-hold diving, suggesting a risk for blackout. Beetroot-induced vasodilation may counteract normal cardiovascular responses during swimming, emphasizing the need for further research to quantify risks. With inconsistent dosing and lack of standardized recommendations, heightened awareness of these risks is crucial for informed decision-making regarding beetroot supplements, especially in tactical athletes.

Birth Outcomes Among First Nations Birthing Parents Incarcerated While Pregnant: A Linked Administrative Data Study From Manitoba, Canada.

BACKGROUND: In Canada, colonial policies have resulted in health inequities between First Nations and other Canadians. These policies contribute to overrepresentation of First Nations in the criminal legal system, where incarcerated people and their infants face elevated health risks. We investigated the association between prenatal incarceration and adverse birth outcomes among First Nations and other birthing parents in Manitoba, Canada. METHODS: Using linked whole-population administrative data, we identified all live births (2004-2017) in which the birthing parent (First Nations n = 1,449; other Manitoban n = 278) was prenatally incarcerated and compared them to birthing parents who were postnatally incarcerated (First Nations n = 5,290; other Manitoban n = 790) or not incarcerated (First Nations n = 19,950; other Manitoban n = 3,203). We used generalized linear models adjusted for measured confounders with propensity score weighting to calculate risk differences and 95% confidence intervals for adverse birth outcomes among those prenatally versus postnatally incarcerated in each group. RESULTS: Low birthweight births were more likely among First Nations birthing parents who were prenatally (vs. postnatally) incarcerated (risk difference 1.59, 95% CI [.79, 2.38]) but less likely among other Manitoban birthing parents (risk difference -2.33, 95% CI [-4.50, -.16]) who were prenatally (vs. postnatally) incarcerated. Among First Nations, prenatal incarceration was also associated with large-for-gestational-age births, low Apgar scores, and no breastfeeding (vs. postnatal incarceration), as well as preterm births (vs. no incarceration). Among other Manitobans, prenatal incarceration was also associated with small-for-gestational-age births, low Apgar scores, and no breastfeeding (vs. postnatal incarceration), as well as preterm births (vs. no incarceration). CONCLUSIONS: The findings suggest that incarceration may contribute to intergenerational systems of oppression by compromising birth outcomes among First Nations and other birthing parents in Canada and underscore the need to both improve care for pregnant people who are incarcerated and invest in alternatives to incarceration.

Fast clustering and cell-type annotation of scATAC data using pre-trained embeddings.

Data from the single-cell assay for transposase-accessible chromatin using sequencing (scATAC-seq) are now widely available. One major computational challenge is dealing with high dimensionality and inherent sparsity, which is typically addressed by producing lower dimensional representations of single cells for downstream clustering tasks. Current approaches produce such individual cell embeddings directly through a one-step learning process. Here, we propose an alternative approach by building embedding models pre-trained on reference data. We argue that this provides a more flexible analysis workflow that also has computational performance advantages through transfer learning. We implemented our approach in scEmbed, an unsupervised machine-learning framework that learns low-dimensional embeddings of genomic regulatory regions to represent and analyze scATAC-seq data. scEmbed performs well in terms of clustering ability and has the key advantage of learning patterns of region co-occurrence that can be transferred to other, unseen datasets. Moreover, models pre-trained on reference data can be exploited to build fast and accurate cell-type annotation systems without the need for other data modalities. scEmbed is implemented in Python and it is available to download from GitHub. We also make our pre-trained models available on huggingface for public use. scEmbed is open source and available at https://github.com/databio/geniml. Pre-trained models from this work can be obtained on huggingface: https://huggingface.co/databio.

Developmental origins of parkinson's disease risk: perinatal exposure to the organochlorine pesticide dieldrin leads to sex-specific DNA modifications in critical neurodevelopmental pathways in the mouse midbrain.

Epidemiological studies show that exposure to the organochlorine pesticide dieldrin is associated with increased risk of Parkinson's disease (PD). Animal studies support a link between developmental dieldrin exposure and increased neuronal susceptibility in the α-synuclein preformed fibril (α-syn PFF) and MPTP models in adult male C57BL/6 mice. In a previous study, we showed that developmental dieldrin exposure was associated with sex-specific changes in DNA modifications within genes related to dopaminergic neuron development and maintenance at 12 weeks of age. Here, we used capture hybridization-sequencing with custom baits to interrogate DNA modifications across the entire genetic loci of the previously identified genes at multiple time points-birth, 6 weeks, 12 weeks, and 36 weeks old. We identified largely sex-specific dieldrin-induced changes in DNA modifications at each time point that annotated to pathways important for neurodevelopment, potentially related to critical steps in early neurodevelopment, dopaminergic neuron differentiation, synaptogenesis, synaptic plasticity, and glial-neuron interactions. Despite large numbers of age-specific DNA modifications, longitudinal analysis identified a small number of DMCs with dieldrin-induced deflection of epigenetic aging. The sex-specificity of these results adds to evidence that sex-specific responses to PD-related exposures may underly sex-specific differences in disease. Overall, these data support the idea that developmental dieldrin exposure leads to changes in epigenetic patterns that persist after the exposure period and disrupt critical neurodevelopmental pathways, thereby impacting risk of late life diseases, including PD.

Inhibition of Renin Expression Is Regulated by an Epigenetic Switch From an Active to a Poised State.

BACKGROUND: Renin-expressing cells are myoendocrine cells crucial for the maintenance of homeostasis. Renin is regulated by cAMP, p300 (histone acetyltransferase p300)/CBP (CREB-binding protein), and Brd4 (bromodomain-containing protein 4) proteins and associated pathways. However, the specific regulatory changes that occur following inhibition of these pathways are not clear. METHODS: We treated As4.1 cells (tumoral cells derived from mouse juxtaglomerular cells that constitutively express renin) with 3 inhibitors that target different factors required for renin transcription: H-89-dihydrochloride, PKA (protein kinase A) inhibitor; JQ1, Brd4 bromodomain inhibitor; and A-485, p300/CBP inhibitor. We performed ATAC-seq, single-cell RNA sequencing, CUT&Tag, and chromatin immunoprecipitation sequencing for H3K27ac and p300 binding on biological replicates of treated and control As4.1 cells. RESULTS: In response to each inhibitor, Ren1 expression was significantly reduced and reversible upon washout. Chromatin accessibility at the Ren1 locus did not markedly change but was globally reduced at distal elements. Inhibition of PKA led to significant reductions in H3K27ac and p300 binding specifically within the Ren1 super-enhancer region. Further, we identified enriched TF (transcription factor) motifs shared across each inhibitory treatment. Finally, we identified a set of 9 genes with putative roles across each of the 3 renin regulatory pathways and observed that each displayed differentially accessible chromatin, gene expression, H3K27ac, and p300 binding at their respective loci. CONCLUSIONS: Inhibition of renin expression in cells that constitutively synthesize and release renin is regulated by an epigenetic switch from an active to poised state associated with decreased cell-cell communication and an epithelial-mesenchymal transition. This work highlights and helps define the factors necessary for renin cells to alternate between myoendocrine and contractile phenotypes.

Diagnostic Prediction Model for Tuberculous Meningitis: An Individual Participant Data Meta-Analysis.

No accurate and rapid diagnostic test exists for tuberculous meningitis (TBM), leading to delayed diagnosis. We leveraged data from multiple studies to improve the predictive performance of diagnostic models across different populations, settings, and subgroups to develop a new predictive tool for TBM diagnosis. We conducted a systematic review to analyze eligible datasets with individual-level participant data (IPD). We imputed missing data and explored three approaches: stepwise logistic regression, classification and regression tree (CART), and random forest regression. We evaluated performance using calibration plots and C-statistics via internal-external cross-validation. We included 3,761 individual participants from 14 studies and nine countries. A total of 1,240 (33%) participants had "definite" (30%) or "probable" (3%) TBM by case definition. Important predictive variables included cerebrospinal fluid (CSF) glucose, blood glucose, CSF white cell count, CSF differential, cryptococcal antigen, HIV status, and fever presence. Internal validation showed that performance varied considerably between IPD datasets with C-statistic values between 0.60 and 0.89. In external validation, CART performed the worst (C = 0.82), and logistic regression and random forest had the same accuracy (C = 0.91). We developed a mobile app for TBM clinical prediction that accounted for heterogeneity and improved diagnostic performance (https://tbmcalc.github.io/tbmcalc). Further external validation is needed.

Dopamine Release Dynamics in the Nucleus Accumbens Are Modulated by the Timing of Electrical Stimulation Pulses When Applied to the Medial Forebrain Bundle and Medial Prefrontal Cortex.

Electrical brain stimulation has been used in vivo and in vitro to investigate neural circuitry. Historically, stimulation parameters such as amplitude, frequency, and pulse width were varied to investigate their effects on neurotransmitter release and behavior. These experiments have traditionally employed fixed-frequency stimulation patterns, but it has previously been found that neurons are more precisely tuned to variable input. Introducing variability into the interpulse interval of stimulation pulses will inform on how dopaminergic release can be modulated by variability in pulse timing. Here, dopaminergic release in rats is monitored in the nucleus accumbens (NAc), a key dopaminergic center which plays a role in learning and motivation, by fast-scan cyclic voltammetry. Dopaminergic release in the NAc could also be modulated by stimulation region due to differences in connectivity. We targeted two regions for stimulation─the medial forebrain bundle (MFB) and the medial prefrontal cortex (mPFC)─due to their involvement in reward processing and projections to the NAc. Our goal is to investigate how variable interpulse interval stimulation patterns delivered to these regions affect the time course of dopamine release in the NAc. We found that stimulating the MFB with these variable stimulation patterns saw a highly responsive, frequency-driven dopaminergic response. In contrast, variable stimulation patterns applied to the mPFC were not as sensitive to the variable frequency changes. This work will help inform on how stimulation patterns can be tuned specifically to the stimulation region to improve the efficiency of electrical stimulation and control dopamine release.

PEPhub: a database, web interface, and API for editing, sharing, and validating biological sample metadata.

BACKGROUND: As biological data increase, we need additional infrastructure to share them and promote interoperability. While major effort has been put into sharing data, relatively less emphasis is placed on sharing metadata. Yet, sharing metadata is also important and in some ways has a wider scope than sharing data themselves. RESULTS: Here, we present PEPhub, an approach to improve sharing and interoperability of biological metadata. PEPhub provides an API, natural-language search, and user-friendly web-based sharing and editing of sample metadata tables. We used PEPhub to process more than 100,000 published biological research projects and index them with fast semantic natural-language search. PEPhub thus provides a fast and user-friendly way to finding existing biological research data or to share new data. AVAILABILITY: https://pephub.databio.org.

Infectious Diseases Physician Management of Cryptococcal Meningitis in North America-Is Single High-Dose Liposomal Amphotericin B Being Used?

Background: Several recent randomized trials have been conducted in resource-limited settings for cryptococcal meningitis that have rapidly innovated international guidelines. The 2010 Infectious Diseases Society of America (IDSA) cryptococcal meningitis guideline has not been updated with recent trials. The 2022 AMBITION-cm trial found that a single 10-mg/kg dose of liposomal amphotericin B plus daily flucytosine and fluconazole for 2 weeks was noninferior to 1 week of amphotericin B deoxycholate with flucytosine. It is unknown whether physicians in high-resource settings are using this regimen or more traditional regimens. Methods: We developed an electronic survey in June 2023 to better understand whether physician members of the IDSA Emerging Infections Network (EIN) and Mycoses Study Group Education and Research Consortium (MSG-ERC) had used the AMBITION-cm induction regimen, would use the regimen in hypothetical clinical scenarios, and what perceived barriers to use existed. Results: A total of 242 of 561 (43%) physicians responded to the survey, of whom 205 provided care for persons with cryptococcal meningitis in the last year. Overall, 29 (14%) had used the AMBITION-cm regimen, and 176 (86%) had not. In various hypothetical clinical scenarios, only ∼10% of 209 respondents selected the AMBITION-cm regimen as preferred. Perceived barriers to uptake included the applicability of trials performed in low-resource settings to high-resource settings, that the regimen is not recommended in the 2010 IDSA guidelines, and the applicability to persons without HIV. Conclusions: Most respondents had not used the single-dose liposomal amphotericin B regimen, but the regimen is being used. Further study of this regimen in other patient populations and settings is necessary.

Cyanobacteriochromes: A Rainbow of Photoreceptors.

Widespread phytochrome photoreceptors use photoisomerization of linear tetrapyrrole (bilin) chromophores to measure the ratio of red to far-red light. Cyanobacteria also contain distantly related cyanobacteriochrome (CBCR) proteins that share the bilin-binding GAF domain of phytochromes but sense other colors of light. CBCR photocycles are extremely diverse, ranging from the near-UV to the near-IR. Photoisomerization of the bilin triggers photoconversion of the CBCR input, thereby modulating the biochemical signaling state of output domains such as histidine kinase bidomains that can interface with cellular signal transduction pathways. CBCRs thus can regulate several aspects of cyanobacterial photobiology, including phototaxis, metabolism of cyclic nucleotide second messengers, and optimization of the cyanobacterial light-harvesting apparatus. This review examines spectral tuning, photoconversion, and photobiology of CBCRs and recent developments in understanding their evolution and in applying them in synthetic biology.

Vascular Endothelial Growth Factor C and D Signaling Pathways as Potential Targets for the Treatment of Neovascular Age-Related Macular Degeneration: A Narrative Review.

The development of treatments targeting the vascular endothelial growth factor (VEGF) signaling pathways have traditionally been firstly investigated in oncology and then advanced into retinal disease indications. Members of the VEGF family of endogenous ligands and their respective receptors play a central role in vasculogenesis and angiogenesis during both development and physiological homeostasis. They can also play a pathogenic role in cancer and retinal diseases. Therapeutic approaches have mostly focused on targeting VEGF-A signaling; however, research has shown that VEGF-C and VEGF-D signaling pathways are also important to the disease pathogenesis of tumors and retinal diseases. This review highlights the important therapeutic advances and the remaining unmet need for improved therapies targeting additional mechanisms beyond VEGF-A. Additionally, it provides an overview of alternative VEGF-C and VEGF-D signaling involvement in both health and disease, highlighting their key contributions in the multifactorial pathophysiology of retinal disease including neovascular age-related macular degeneration (nAMD). Strategies for targeting VEGF-C/-D signaling pathways will also be reviewed, with an emphasis on agents currently being developed for the treatment of nAMD.

Comparison of early fungicidal activity and mortality between daily liposomal amphotericin B and daily amphotericin B deoxycholate among patients with HIV-associated cryptococcal meningitis.

BACKGROUND: Limited data exist on the antifungal activity of daily liposomal amphotericin B with flucytosine induction regimens for cryptococcal meningitis, which are recommended in high-income countries. Liposomal amphotericin B monotherapy at 3 mg/kg previously failed to meet non-inferiority criteria compared to amphotericin B deoxycholate in its registrational clinical trial. We aimed to compare the quantitative antifungal activity and mortality between daily amphotericin B deoxycholate and daily liposomal amphotericin among persons with HIV-related cryptococcal meningitis receiving adjunctive flucytosine 100 mg/kg/day. METHODS: We analyzed data from three clinical studies involving participants with HIV-associated cryptococcal meningitis receiving either daily liposomal amphotericin B at 3 mg/kg/day with flucytosine (N = 94) or amphotericin B deoxycholate at 0.7-1.0 mg/kg/day with flucytosine (N = 404) as induction therapy. We compared participant baseline characteristics, CSF early fungicidal activity (EFA), and 10-week mortality. RESULTS: We included 498 participants in this analysis, of whom 201 had available EFA data (N = 46 liposomal amphotericin; N = 155 amphotericin deoxycholate). Overall, there is no statistical evidence that the antifungal activity of liposomal amphotericin B (mean EFA = 0.495 log10 CFU/mL/day; 95%CI, 0.355-0.634) differ from amphotericin B deoxycholate (mean EFA = 0.402 log10 CFU/mL; 95%CI, 0.360-0.445) (P = 0.13). Mortality at 10 weeks trended lower for liposomal amphotericin (28.2%) vs amphotericin B deoxycholate (34.6%) but was not statistically different when adjusting for baseline characteristics (adjusted Hazard Ratio = 0.74; 95%CI, 0.44-1.25; P = 0.26). CONCLUSIONS: Daily liposomal amphotericin B induction demonstrated a similar rate of CSF fungal clearance and 10-week mortality as amphotericin B deoxycholate when combined with flucytosine for the treatment of HIV-associated cryptococcal meningitis.

Providers' and survivors' perspectives on the availability and accessibility of surgery in gastrointestinal cancer care.

BACKGROUND: Surgery is essential for gastrointestinal (GI) cancer treatment. Many patients lack access to surgical care that optimizes outcomes. Scarce availability and/or low accessibility of appropriate resources may be the reason for this, especially in economically disadvantaged areas. This study aimed to investigate providers' and survivors' perspectives on barriers and facilitators to the availability and accessibility of surgical care. METHODS: Semistructured interviews informed by surgical disparities and access-to-care conceptual frameworks with purposively selected GI cancer providers and survivors in Alabama and Mississippi were conducted. Survivors were within 3 years of diagnosis of stage I to III esophageal, pancreatic, or colorectal cancer. Transcripts were analyzed using inductive thematic and content analysis techniques. Intercoder agreement was reached at 90 %. RESULTS: The 27 providers included surgeons (n = 11), medical oncologists (n = 2), radiation oncologists (n = 2), a primary care physician (n = 1), nurses (n = 8), and patient navigators (n = 3). This study included 36 survivors with ages ranging from 44 to 87 years. Of the 36 survivors, 21 (58.3 %) were male, and 11 (30.6 %) identified as Black. Responses were grouped into 3 broad categories: (i) transportation/geographic location, (ii) specialized care/testing, and (iii) patient-/provider-related factors. The barriers included lack and cost of transportation, reluctance to travel because of uneasiness with urban centers, low availability of specialized care, overburdened referral centers, provider-related referral biases, and low health literacy. Facilitators included availability of charitable aid, centralizing multidisciplinary care, and efficient appointment scheduling. CONCLUSION: In the Deep South, barriers and facilitators to the availability and accessibility of GI surgical cancer care were identified at the health system, provider, and patient levels, especially for rural residents. Our data suggest targets for improving the use of surgery in GI cancer care.

Hearing preservation outcomes using direct cranial nerve eight and auditory brainstem response neuromonitoring in the resection of vestibular schwannomas.

OBJECTIVE: Advancements in microsurgical technique and technology continue to improve outcomes in patients with skull base tumor. The primary cranial nerve eight monitoring systems used in hearing preservation surgery for vestibular schwannomas (VSs) are direct cranial nerve eight monitoring (DCNEM) and auditory brainstem response (ABR), although current guidelines are unable to definitively recommend one over the other due to limited literature on the topic. Thus, further research is needed to determine the utility of DCNEM and ABR. The authors performed a retrospective cohort study and created an interactive model that compares hearing preservation outcomes based on tumor size in patients receiving ABR+DCNEM and ABR-only monitoring. METHODS: Twenty-eight patients received ABR+DCNEM and 72 patients received ABR-only monitoring during VS hearing preservation surgery at a single tertiary academic medical center between January 2008 and November 2022. Inclusion criteria consisted of adult patients with a preoperative American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) hearing classification of A or B. Tumor size was measured as the maximal medial to lateral length, including the internal auditory canal component. RESULTS: Overall hearing preservation (word recognition score [WRS] > 0%) was achieved in 31 patients with ABR-only monitoring (43.1%) and in 18 patients with ABR+DCNEM (64.3%). Serviceable hearing preservation (AAO-HNS class A or B) was attained in 19 patients with ABR-only monitoring (26.4%) and in 11 patients with ABR+DCNEM (39.3%). There was no difference in overall hearing preservation between the two groups (p = 0.13). Change in tumor size was not associated with the odds of serviceable hearing preservation for the ABR-only group (p = 0.89); however, for ABR+DCNEM, there was some indication of an interaction between tumor size and the association of ABR+DCNEM versus ABR-only monitoring, with the odds of serviceable hearing preservation at p = 0.089. Furthermore, with ABR+DCNEM, every 0.5-cm increase in tumor size was associated with a decreased odds of serviceable hearing preservation on multivariable analysis (p = 0.05). For both overall and serviceable hearing preservation, a worse preoperative AAO-HNS classification was associated with a decreased odds of preservation (OR 0.43, 95% CI 0.19-0.97, p = 0.042; OR 0.17, 95% CI 0.053-0.55, p = 0.0031, respectively). CONCLUSIONS: The result of this interactive model study proposes that there may be a higher chance of hearing preservation when using ABR+DCNEM rather than ABR alone for smaller tumors, with that relationship reversing as tumor size increases.

Improving the direct air capture capacity of grafted amines via thermal treatment.

This study investigates the effects of elevated temperature thermal treatments on the direct air capture of CO2 by aminosilane-grafted SBA-15 silica sorbents. Exposing samples to high temperatures (200-250 °C compared to 80-120 °C) in an inert environment resulted in improved CO2 capacity (5-21%) that was sustained over multiple adsorption/desorption cycles.