Future Research
The primary field of research that DMT Quest will be focusing on facilitating is regarding endogenous dimethyltryptamine (DMT). However, many of the proposed studies will also need to include research into 5-MEO-DMT (5-methoxy-N,N-dimethyltryptamine), bufotenine (5-HO-DMT) as well as endogenous monoamine oxidase inhibitors (tribulin, neurocatin, tryptoline, harmine, and pinoline). A comprehensive research program including the entire “Endohuasca” system is in order to better understand the dynamic interplay between these complementary biochemicals. In order to avoid redundancy, we preface this section by stating that it is inherently implied that all of the following proposed studies will also include future research into the complementary molecules cited. We also add a short section of exogenous DMT studies at the end of this list although it is not the primary focus of DMT Quest.
*We will be updating this list regularly to include additional ongoing studies from the advisory panel.
Endogenous DMT Research
1. Establishing definitively whether DMT is a neurotransmitter or not. At this point it is clear that DMT is produced throughout the mammalian brain based on the 2019 study published in Scientific Reports. In our interview with Dr. Jimo Borjigin from the University of Michigan she states that a specific study of establishing DMT as a neurotransmitter is her primary focus in 2019/2020.
2. Researching the mechanisms of DMT synthesis and how it’s release is regulated. Well studied neurotransmitters such as serotonin, dopamine, and norepinephrine have all been observed to follow a pattern of excretion based on circadian rhythm, various levels of stress, and fluctuating levels of sedation. It seems reasonable to hypothesize that DMT synthesis and excretion follow similar patterns.
3. Identifying the cells in the brain that synthesize DMT (neurons and/or astrocytes). While Dr. Jimo Borjigin hypothesizes that DMT is synthesized in the D-neurons that potentially contain the 2 enzymes (INMT/AADC) necessary for synthesis, we respectfully include neuroglia cells named astrocytes. We believe that periphery evidence indicates that astrocytes could be a reasonable neural cell of inquiry based on the research showing that astrocytes synthesize other neurotransmitters glutamate, GABA, Nitric Oxide, and even melatonin.
4. A human brain PET scan for DMT measurement. Positron-emission tomography (PET) is a nuclear medicine functional imaging technique that is used to observe metabolic processes in the body. The scan captures images of the activity of the brain after radioactive “tracers” have been absorbed into the bloodstream. These tracers are “attached” to compounds and used to measure glucose metabolism, blood–brain barrier transport, and neurotransmitter release. Due to the invasive and risky nature of research involving microdialysis probes in live human brains, PET offers a non-invasive method to measure for DMT. Some researchers claim that this methodology is the only manner in which live human brains can be directly measured for neurotransmitter synthesis rates.
5. The role of DMT in Near Death Experiences (NDE’s) following cardiac arrest. While the recent 2019 study by the University of Michigan observed a 2-fold increase of DMT in the visual cortex following cardiac arrest, this wasn’t immediately following cardiac arrest. A replication of the 2015 study which measured the fluctuation of many different neurotransmitters, but this time to include DMT measurement is necessary.
6. The role of DMT during dream states and dream lucidity. It’s long been hypothesized that endogenous DMT correlates with the dream state being that DMT is a known hallucinogen and that dreams are essentially nocturnal, closed-eye hallucinations. In light of the recent 2019 study regarding the levels of endogenous DMT in comparison to other neurotransmitters (serotonin, dopamine, norepinephrine), it would hardly be surprising if DMT contributed to the visions experienced during dreams.
7. The relationship between dream lucidity, DMT and the externally derived stimulation of 40 Hz gamma waves. A 2014 study published in Nature Neuroscience observed that dream lucidity (self-awareness) could be induced by transcranial alternating current stimulation (tACs) in the lower gamma frequency range (25 to 40 Hz). Stimulating the fronto-temporal region of the brain at slower (2, 6, & 12Hz) and faster frequencies (70 & 100 Hz) failed to induce such effects. Replicating this study while measuring visual cortex and cerebral cortex DMT levels would add additional insight into the role DMT plays in modulating gamma wave activity as well as higher order consciousness.
8. The role of DMT in modulating gamma wave activity. There are 5 main brain waves that have been categorized when measuring brain activity using electroencephalography (EEG) and/or magnetoencephalography (MEG). The slowest to fastest… delta (0 to 4 Hz), theta (4 to 8 Hz), alpha (8 to 12 Hz), beta (12 to 25 Hz), and gamma (25 to 100 Hz (or more)). The research regarding exogenous DMT and Ayahuasca indicates that gamma wave activity increases during the visionary experiences alongside a decrease in slower wave activity. Additional research regarding meditation, rem sleep (dreams), lucid dreams, and hypnosis have also observed increases in gamma wave activity. There are various ways to measure DMT correlations with gamma activity. The first one being INMT-KO animal studies in which circulating DMT levels are suppressed compared to wild-type animals and whether researchers observe any change in gamma wave activity. The second one is based on the study proposed above where 40 Hz gamma is induced in the brain and circulating DMT levels are measured (via PET scan?) to verify whether a correlation exists.
9. The role of DMT in the placebo effect. While this will undoubtedly be a difficult area of research to quantify, it’s possible that DMT plays a role as a biochemical correlate of the effect of intent as well as autonomic nervous system influence. The subtleties and nuanced effects of “placebo” create challenges to research and measure the phenomena but it’s a worthwhile endeavor nonetheless.
10. The role of DMT in visual/mental imagery, autonomic signaling and effects. While DMT is known for it’s “hallucinatory” effects, visual/mental imagery is the process of visualizing something in one’s imagination. In essence, it could be considered a form of “conscious hallucination”. One of the more intriguing aspects of “conscious hallucinations” is that they have the ability to effect a person’s own physiology. An example of this is the 2014 fMRI-EEG study (video summary below) which observed that visual imagery of a person’s hand immersed in ice cold water coupled with hypnosis induced a measurable drop in temperature of the visualized hand. Whether DMT is upregulated during in the brain and/or periphery during these moments of visualization should be investigated.
11. The fluctuations of endogenous DMT correlating with 24 hour circadian rhythms. Many other biochemicals utilized in the brain exude a certain rhythm based on the dark-light cycle. Currently there are no studies in regards to measuring brain DMT level fluctuations based on this cycle which is needed.
12. The interaction and fluctuations between endogenous monoamine oxidase inhibitors (MAOI’s) tribulin, tryptoline, harman, neurocatin, pinoline and DMT(s). In the 1980’s and early 1990’s, the endogenous MAOI tribulin generated notable interest as over 50 individual studies were carried out on this compound. Much like past DMT studies indicate that increased stress coincides with an increase in DMT release, stress studies have also observed increases in tribulin release. This alludes to a potential interplay between endogenous DMT and endogenous MAOI which would not be surprising considering the preservative effects of MAOI on monoamine neurotransmitter deamination. A future study exploring the interactions between multiple endogenous MAO-A inhibitors and DMT synthesis/release is necessary.
13. The potential upregulation of DMT synthesis based on cannabis ingestion. While the chemical compounds found in cannabis stimulate cannabinoid receptors directly rather than the serotonergic receptors deemed predominantly responsible for the effects of DMT, there have been many reports of DMT-like experiences in some people following cannabis ingestion. A 2018 study in Neuropsychopharmacology found that chronic cannabis usage promotes pro-hallucinogenic signaling of 5-HT2A receptors through Akt/mTOR pathway. Another 2018 study published in Molecular Neurobiology observed that cannabis users showed enhanced expression of CB1-5HT2A receptor heteromers in olfactory neuroepithelium cells. A study measuring the acute effects of cannabis (both inhaled and orally ingested) on endogenous DMT release as well as long-term cannabis use on baseline DMT levels is in order.
14. The potential upregulation of DMT synthesis based on LSD ingestion. In an interview DMT researcher Dr. Steven Barker did for “DMT: The Spirit Molecule” documentary, he cited an intriguing unpublished animal LSD study. Barker stated in the interview that following LSD administration to rats, it was found that their 5-MEO-DMT levels surged 1000% and their DMT levels rose 400%. This led him to postulate that there lies the possibility that mammals have an endogenous hallucinatory system and that a lot of hallucinogens might just be activating that system rather than simply acting on their own. This study could be replicated using LSD, psilocybin, and even non-serotonergic compounds such as Ketamine and MDMA.
15. The effects of breathing exercises Wim Hof Method, Holotropic Breathwork, Joe Dispenza’s meditation on DMT synthesis and release. Hundreds of thousands of people who have partaken in extended breathing exercises have reported “hallucinatory” experiences comparable to DMT (many who have tried both have confirmed). Possibly a PET scan in which the proper tracers have been developed can be utilized to measure fluctuations in endogenous DMT synthesis in the brain prior, during, and following these breathing practices. Based on the recent 2019 DMT study, it wouldn’t be surprising to see an upregulation of DMT alongside fluctuations in other common neurotransmitters dopamine, serotonin, and norepinephrine.
16. The effects of meditation and yoga techniques on DMT synthesis and release. While there are many different types of meditations (Transcendental, Mindfulness, Zen) and Yoga (Kriya, Kundalini), nearly all of them have been experientially reported to induce significant alterations in consciousness. However, identifying the biochemical correlates of these experiences has not been undertaken involving endogneous DMT.
17. The effects of external magnetic fields (God Helmet, tDCS, tACs, etc.) on the brain, DMT synthesis and release. Many subjects who have undergone exposure to ultra weak magnetic fields via Dr. Michael Persinger’s “God Helmet“ have reported “mystical” experiences. Dr. Persinger would observe increases in gamma wave power from these exposures and also hypothesized that DMT could be involved as a biochemical modulator of these experiences. However, a formal study has yet to take place regarding the “God Helmet” in regards to DMT upregulation. In addition, while the neuroplastic properties of exogenous DMT and Ayahuasca have been well documented, transcranial direct current stimulation (tDCs) and transcranial alternating current stimulation (tACs) have also been observed to induce neuroplasticity. Further research into the potential upregulation of endogenous DMT during and following tDCS/tACs therapy could provide insights into the mechanisms of action.
18. The effects of Light devices such as Ajna Light, Lucia Light, Pandora Star on DMT synthesis and release. These light systems that have been specifically developed to induce altered states of consciousness have been reported to consistently generate visionary experiences. A definitive study to better understand the mechanisms for these visionary experiences and possibly endogenous DMT’s role in them is necessary.
19. The effects of general hypnosis on DMT synthesis and release. One of the commonalities in terms of the above mentioned techniques hypothesized to correlate with DMT upregulation is that they generally are based on inducing a relaxative, trance state. Hypnosis is predicated upon specifically inducing a relaxed, trance state in order for the subject to increase their receptivity to suggestion. One of the mysterious states of deep hypnosis is labeled as “The Esdaile State” in which a person’s body can become extremely stiff and seemingly impervious to pain. This is interesting in light of studies indicating the analgesic effects of 5-MEO-DMT (Brain Research – 1985, Acta Pharmacologica et Toxicologica – 1986, Physiology & Behavior – 1987, Journal of Neurotransmission – 1988.) A study measuring whether a standard induction and hypnotic deepening techniques (various levels) without any specific instructions alters DMT synthesis and release would be important to better understand the physiological correlates of hypnosis.
20. The effects of specific visionary hypnosis on DMT synthesis and release. While the previously suggested study is based on the effects of general hypnosis on endogenous DMT, this study would be based on specific hypnotic instructions. What we are referring to when stating “specific instructions” has to do with a subject asked to visualize an occurrence or even visualize things like an “Out of Body Experience” (Sage Open – 2015, Cortex – 2017, The International Journal of Clinical and Experimental Hypnosis – 2019). Periphery hypnosis studies indicate that the body can respond to specific instructions and possibly release specific biochemicals when in the trance state. A study regarding specific visual based instructions while under hypnosis would provide insights into potentially DMT’s role in inducing these experiences. An even more adventurous study could involve people who have ingested exogenous DMT to be hypnotically “regressed” to that experience and verifying whether they can re-experience the DMT moments in this manner.
21. The effects of sensory deprivation tank exposure on DMT synthesis and release. This would be a challenging study to carry out but it’s possible once less invasive yet specific correlates of endogenous DMT upregulation have been identified (such as EEG bands). Sensory deprivation tank exposure consists of floating in 93.5 degree (F) water infused with 800 pounds of epsom salt. The concentration of salt creates a viscosity in the water allowing a person to remain effortlessly buoyant. The subject then has the option to float in low light conditions or complete darkness. In a 2018 PLOS One study, subjects reported commonly experiencing feelings such as extreme tranquility and euphoria, Less commonly reported experiences were auditory & visual hallucinations as well as “Out of Body Experiences”. Based on the euphoric effects of sub-psychedelic doses of DMT in Rick Strassman’s study, we hypothesize that endogenous DMT could be upregulated from sensory deprivation tank exposure.
22. The effects of audio (music, binaural beats) on DMT synthesis and release. Different types of purported audio entrainment tracks have been reported to induce altered states of consciousness. While visual hallucinatory properties are rare in terms of the acute effects of audio exposure, heightened emotional response and neuroplasticity have been well documented as a consequence of regular music exposure. There is the likelihood that modest upregulation of endogenous DMT coincides with these effects of music and sound.
23. The effects of prolonged darkness on DMT synthesis and release. While sleep quarters and sensory deprivation offer modest exposure to darkness, “dark room retreats” consist of eastern spiritual practices in which a person is willfully sequestered to a pitch black environment anywhere from a few days to a few weeks. Throughout this exposure to darkness and prolonged meditation, many experiencers have reported profound visionary states. A member of our advisory panel, Dr. Edith Ubuntu Chan describes some of her experiences during an 11-day dark room retreat in this article. It’s largely been speculated that changes in DMT synthesis take place from this prolonged exposure to complete darkness however a formal study is in order to better understand the mechanisms of these visionary states.
24. The effects of singing/chanting on DMT synthesis and release. Singing and chanting have long been integrated in various cultures worldwide as methods of inducing altered states. Pilot studies regarding the physiological effects of the famous “OM” mantra observed limbic deactivation/vagus nerve stimulation (fMRI) as well as a significant global increase in theta wave power (EEG study) following 30 minutes of the exercise. There lies the possibility that the physical vibrations and/or specific oscillatory rhythms of certain regions of the nervous system contribute to altered secretions of certain biochemicals including DMT.
25. The effects of dietary inputs and fasting on DMT levels. While we believe it’s clear that orally ingested DMT has little effects on endogenous DMT levels, there lies the possibility certain dietary factors can lead to upregulation or downregulation of monoamine oxidase (MAO) activity. MAO is the enzyme that deaminates DMT as well as other monoamines (dopamine, serotonin, norepinephrine). It appears that many different substances inhibit MAO activity which might potentially lead to increases in endogenous DMT synthesis and release (natural herbs, tobacco). A 2009 study in the Journal of Physiology and Biochemistry observed that prolonged fasting (3 days) in rats induced a 50% reduction in MAO activity in intra-abdominal adipose tissue. A 1992 study in the Journal of Pineal Research measured for changes in tryptophan, serotonin, 5-HIAA, and melatonin in the brain and the gastrointestinal tract of fed mice compared to mice fasted for 24 and 48 hrs. There were variations in many of these compounds when comparing fed to fasted mice but melatonin was found to have increased in all tissues of the fasted mice especially in the stomach and brain tissue. There’s potential that specific dietary inputs and/or fasting regimens can create alterations DMT synthesis & release leading to neuroplastic effects and changes in cognition/mood.
26. The potential secretion of DMT throughout the gastrointestinal tract (similar to serotonin & melatonin). While the biochemicals serotonin and melatonin are most well known for having a pineal origin and modulating brain function, it is confirmed that more than 90% of serotonin is synthesized in the gut and that the gut contains 400 times more melatonin than the pineal gland. A 2005 study found significant amounts of bufotenine (5-HO-DMT) in the stool of humans. The researchers proposed that glandular epithelial cells of the small and large intestine are possibly the source of bufotenine in the stool. Further study is necessary to better understand the possible synthesis and release of all 3 DMT(s) in the gut and their possible role in gut barrier integrity.
27. Measure fluctuations of endogenous magnetic field generation and endogenous DMT release fluctuations. While communication throughout the body is largely perceived to be an electro-chemical endeavor, physics 101 dictates that electrical oscillations generate magnetic fields. Magnetoencephalography (MEG) is the type of equipment utilized to measure fluctuations in magnetic fields generated by the brain. Being that ultra-weak magnetic fields (1 to 5 microtesla) such as those created by the “God Helmet” can influence perception as well as the recent discovery that humans can sense earth’s magnetic field (25 to 65 microteslas), the influence of magnetic fields in terms of perceptual changes and biochemical release is an interesting field of inquiry.
28. Measure biophoton emanation fluctuations and endogenous DMT release fluctuations. Biophotons are photons of light that are generated within the body and are constantly radiated from the body surface. These spontaneous emissions are thought to be associated with generation of free radicals due to energy metabolic processes. Mammalian brains have been observed to produce biophotons between 200 (ultraviolet) and 1,300 nanometers (near infrared). Alterations in biophoton count emanation and wavelengths have been observed to coincide with meditation, cancer cell proliferation, and visualization. Some scientists hypothesize that myelinated axons could serve as biophotonic waveguides and that potential neuronal biophotonic communication should be explored. Better understanding the various wavelengths of light particle emanations and endogenous DMT synthesis and release would provide further insights into the biophotonic activity of altered states.
29. The correlations between DMT synthesis/release and interbrain synchronization between 2 or more mammals. There are various studies indicating that humans can experience interbrain synchronization when communicating with each other via eye contact, physically touching, while listening to music together, and using verbal communication. Other studies indicate that brain synchronization between subjects is possible without any obvious traditional form of communication (sound, sight, touch, smell). The effects of exogenous DMT have been experientially reported to increase a “feeling” of connectivity with others. There lies the potential that this feeling of being “in-sync” with another person(s) coincides with DMT upregulation in a subtle manner.
30. The potential correlations between sleep paralysis and DMT synthesis and release. Sleep paralysis is a phenomena described as generally taking place immediately prior to falling asleep or during moments of waking up from sleep. The common description is based on having an inability to move one’s body and some people even describe hallucinatory images. While roughly 8 percent of the population experiences sleep paralysis regularly, a much higher percentage of people have experienced the phenomena at least once in their lives. Exploring any possible correlations between endogenous DMT and sleep paralysis would generate important insights into the experience.
31. The potential correlations between “Out of Body Experiences” and DMT. The “Out of Body Experience” (OBE) has been described as the experience of seeing one’s own body from above or alongside itself. There are various methods in which OBE’s have been induced in people including but not limited to cardiac arrest, physical trauma, hypnosis, and meditation. There are even organizations such as “The Monroe Institute“ and “The International Academy of Consciousness“ that have developed specific OBE techniques over decades of research. Due to the various methods of accessing OBE’s and the commonality of occurrence, further research into the biochemical correlations and possibly DMT with the phenomena is needed.
32. Measure complementary endogenously produced compounds during and following cardiac arrest such as Alpha-Endopsychosin, Morphine, Adrenochrome, Dynorphin, and Gamma-hydroxybutric Acid (GHB). While DMT is the most popularly discussed endogenous hallucinatory compound, these other biochemicals have also been proposed as potential biochemical correlates of “hallucinatory” experiences. A replication of these studies listed above alongside the measurement of all these chemicals alongside the three DMT’s and monoamine oxidase inhibitors would provide a comprehensive picture of the biochemical soup that correlates with the experience.
33. A peripheral nervous system investigation of DMT synthesis. While the focus of the DMT research is largely based on the effects on the brain, it seems as though there is enough evidence to explore it’s role in the periphery. DMT has been observed to exude anti-inflammatory effects via the Sigma-1 receptor throughout the central nervous system and the peripheral nervous system. Exploring the potential of mast cell synthesis of DMT might offer some insights being that mast cells synthesize serotonin and melatonin in the periphery. The effects of peripheral DMT and myelin formation is also an interesting field of inquiry being that myelin sheath thickness dictates the potential speed of signal transmission.
Exogenous DMT Research
34. The effects of exogenous DMT on wound healing. Dr. Ede Frecksa wrote an article regarding the potentiality of DMT to modulate tissue regeneration in the periphery via stimulation of the Sigma-1 receptor. In this study we would apply DMT to the site of the wound healing and monitor the healing process compared to an untreated wound of another animal. There lies the possibility that much like melatonin has been observed to accelerate wound repair, DMT exudes similar abilities based on it’s anti-oxidant, anti-inflammatory actions.
35. The effects of exogenous DMT on bone fracture healing. While bone fracture healing is viewed as a more complex process then superficial wound healing, it would offer additional insights into the potential multi-faceted roles endogenous DMT could play in regeneration. While melatonin has been observed to accelerate bone fracture healing in animal studies, it would be important to compare the effects of DMT on similar fractures to deduce which compound provides a greater effect.
36. The effects of sub-psychedelic DMT doses on mood, neuroplasticity, and depression.In Rick Strassman’s exogenous DMT study in the early 1990’s, he administered varying levels of DMT to the volunteers. Two of the four doses were sub-psychedelic meaning that the amount of DMT administered failed to induce any visionary experiences. However, mood alteration and feelings of euphoria were reported at doses of 0.05mg/kg. There lies the potentiality that consistent administration of sub-psychedelic doses of DMT can provide significant improvements in mood, depression, and even influence neuroplasticity in humans without the visionary effects of high dose DMT. A 2019 study of microdosing DMT in rats observed positive effects in mood and anxiety.
37. The administration of DMT and melatonin synchronously while measuring subsequent experiential effects. One of the heavily speculated topics regarding naturally induced altered states of consciousness is the role of melatonin. While melatonin has been observed to follow a circadian rhythm in which it’s secretion levels increase during the night and decrease during the day, there is also research indicating that it is brain wave dependent. Canadian neuroscientist, Dr. Ranjie Singh has done research in this specific field and has confirmed that melatonin secretion can be altered via inducing relaxative techniques. Precisely how melatonin and DMT interact in terms of modulating dreams and other visionary experiences has yet to clinically researched. A future study in which melatonin is administered alongside DMT while measuring for any significantly different effects than DMT alone would provide some insights into the effects of the combination.
38. The effects of DMT on brain direct current (DC) measurements as well as magnetic field changes inside and outside of the body. Many people who have experienced DMT have expressed an occurrence of perceived physical inner pressure or tension associated with the journey. We hypothesize that distinct changes in the electric oscillatory activity throughout the brain and body possibly coincide with a change in magnetic fields measured internally as well as externally surrounding the body. Some insights could be generated by administering DMT intravenously to subjects and measuring the alterations in electric fields, magnetic fields, and biophotonic emanations during the experience.
39. Prolonged intravenous DMT and the effects on human perception (both sub-psychedelic and psychedelic). This appears to be a study that Imperial College in the UK is interested in attempting to carry out. While it seems as though the focus will be to keep a sustained level of “breakthrough” DMT levels in the human system, there are also interesting possibilities from prolonged sub-psychedelic doses of DMT in a person. While the high doses would attempt to allow the researchers and subjects to map out the visionary realms, the low doses could afford insights into the rapid, emotionally therapeutic potential of DMT.
40. Observe the cerebral cascade effect levels of exogenous DMT in order to better understand the biochemical matrix balance of endogenous DMT upregulation. This study would be aimed at better understanding the balance of biochemicals leading to the experiential effects of exogenous DMT as well as naturally induced visionary states. In Dr. Rick Strassman’s exogenous DMT human study he observed a dose dependent increase in blood concentrations of β-Endorphin, cortisol, corticotropin, and prolactin levels (growth hormone rose equally to all doses). This data alludes to the notion that exogenous DMT does not act singularly and instead creates it’s effects by inducing multiple chemical release alongside it’s own receptor agonistic properties. This is not unlike the possible correlations of the 2015 Proceedings of National Academy of Sciences study which observed that numerous neurotransmitters increased significantly following cardiac arrest. DMT levels were not measured in this study but it’s clear that if DMT is upregulated in the brain directly following cardiac arrest that it is not solely responsible for the experience. There lies the potentiality that the amount of DMT involved in modulating the NDE experience is much less than the amount needed to induce a mystical experience exogenously due to the naturally supportive roles of multiple neurotransmitters acting in synergy.
41. (Warning: Controversial) Death with dignity + DMT intravenous. In 2016, a story broke about a woman named Betsy Davis who had been suffering from severe complications of amyotrophic lateral sclerosis (ALS). She decided to throw a farewell party to her friends prior to taking her own life utilizing the End of Life Option Act. Davis’ would request that everyone attending the 2-day party refrain from crying in her presence and instead to use the time to remember the great times in her life. While this is a sensitive topic there is the possibility that some patients that utilize the End of Life Option Act are curious about the after life. A subjective study in which the patient administers the lethal concoction and their friends/family/volunteers simultaneously receiving intravenous DMT might provide some insight. Dr. Raymond Moody has done extensive research into the phenomena of “Shared Death Experiences” which seemingly might have some potential overlap.