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News Article | April 20, 2017
Site: phys.org

Magdon-Ismail is the co-founder of Venmo, the payment service that allows people to send each other cash for any purpose whatsoever. He spoke with the AP about how Venmo got started and how his unique upbringing helped spark the concept for Venmo, which is now owned by PayPal. Below are the highlights of the interview, edited for length and clarity. Q: How did you and your co-founder come up with the idea for Venmo? A: We came up with the idea over a series of brainstorming sessions. The first one was at a bar in Philadelphia where my friend was playing with his band. There's a common thing bands do where they pass a tip bucket around, and they were asking for everyone in the audience to give them cash to buy some beers at the end of the night if you enjoyed the show. And (Andrew) Kortina and I, the other co-founder of Venmo, were wondering about ways to tip the band without having to go down and put cash in the bucket, and that's kind of where the original idea for Venmo started. We kind of let the idea sit for a while. About two or three weeks later I went up to visit him in New York and we were just hanging out. When I left my place I forgot to take my wallet. I had my BlackBerry with me, and then that's kind of when this behavioral concept of people always carrying their phones everywhere they go started to click with us. Q: As a kid, were you entrepreneurial? Were you into coming up with business ideas? A: I was kind of into more of the arts and entertainment than I was in entrepreneurship, actually. I did a lot of theatre and music growing up. I was born and raised in Zimbabwe and then I moved to Zambia and Uganda. It was only when I was 14 that I moved to America. With my time in Africa I didn't really have sort of these aspirations of building companies. However when I got to America I moved to Virginia—Fairfax County—and eventually I went to Langley High School, and I started to be surrounded by a lot of kids that had parents that were building their companies and starting companies. Q: When you think about financial transactions, you typically think about this assurance of privacy and security. Do you think that some of the privacy and security issues are less important to millennial customers than they were to maybe an older generation of traditional banking? A: No, no, no. I think privacy is very, very important, in fact, in Venmo it's also very important. On Venmo you can be completely private. You can make all your payments private. It's just, I do think millennials are more open to sharing things about themselves, however there are millennials that want to be completely private and they should be allowed to do that. Q: You were acquired by Braintree, who sold you to PayPal. Do you have any regrets about selling the company or that initial acquisition? A: I have no regrets about selling the company to Braintree or PayPal. I think it was really, really good and a really, really good outcome for the people of Venmo. A lot of people have asked me in the past, 'you think you could've made more money if you just held on to Venmo a little longer?' The way I tell it, Braintree saved Venmo's life. We were in a very bad financial state right before the acquisition to the point where Braintree actually paid our salaries in advance because we didn't have enough cash in our bank account to cover our expenses, and I think we couldn't have wished for Venmo anything better than that acquisition. Q: Any advice that you'd give yourself during that period of hardship, looking back at that experience now? A: Have faith. I tell myself all the time. Just kind of follow your instinct and your gut and believe in whatever you're working on or doing or thinking about. Sometimes I need to remind myself that that's the best approach to living. That's advice I give myself almost every day. Explore further: Fast money: Banks making it easier to split the tab


Spassova M.A.,U.S. Environmental Protection Agency | Miller D.J.,U.S. Environmental Protection Agency | Eastmond D.A.,University of California at Riverside | Nikolova N.S.,Langley High School | And 4 more authors.
Environmental and Molecular Mutagenesis | Year: 2013

Mutagenic agents have long been inferred to act through low-dose linear, nonthreshold processes. However, there is debate about this assumption, with various studies interpreting datasets as showing thresholds for DNA damage and mutation. We have applied rigorous statistical analyses to investigate the shape of dose-response relationships for a series of in vitro and in vivo genotoxicity studies using potassium bromate (KBrO3), a water ozonation byproduct that is bioactivated to a reactive species causing oxidative damage to DNA. We analyzed studies of KBrO3 genotoxicity where no-effect/threshold levels were reported as well as other representative datasets. In all cases, the data were consistent with low-dose linear models. In the majority of cases, the data were fit either by a linear (straight line) model or a model which was linear at low doses and showed a saturation-like downward curvature at high doses. Other datasets with apparent upward curvature were still adequately represented by models that were linear at low dose. Sensitivity analysis of datasets showing upward curvature revealed that both low-dose linear and nonlinear models provide adequate fits. Additionally, a simple biochemical model of selected key processes in bromate-induced DNA damage was developed and illustrated a situation where response for early primary events suggested an apparent threshold while downstream events were linear. Overall, the statistical analyses of DNA damage and mutations induced by KBrO3 are consistent with a low-dose linear response and do not provide convincing evidence for the presence of a threshold. © 2012 Wiley Periodicals, Inc.


Choi W.,Langley High School | Lee J.H.,Luminescent
Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013 | Year: 2013

Rapid single nucleotide polymorphism (SNP) with 1, 1'-oxalylimidazole chemiluminescence (ODI-CL) detection was developed for the early diagnosis of human mad-cow disease. Mutated single strand DNA (ssDNA) sequence discovered from patients having human mad-cow disease rapidly hybridize with complementary probe conjugated with chemiluminescent dye. The hybridization between target ssDNA and complementary probe was dependent on four different variables such as pH, temperature, incubation time, and the type of nanoparticles (e.g., multi-walled carbon nanotubes, graphene oxide) capable of capturing mismatched ssDNAs and excess complementary probe. However, three different types of mismatched ssDNAs also slowly hybridize with complementary probe with the increase of incubation time. The problem was solved by using ODI-CL detection instead of fluorescence detection of conventional SNP because ODI-CL is about 100 times more sensitive than fluorescence. In other words, it was possible to reduce the interaction between mismatched ssDNAs and complementary probe with short incubation time (15 minutes) using highly sensitive ODI-CL detection. Based on the results, in conclusion, it is expected that SNP with ODI-CL can be applied as a cost-effective, rapid, and simple analytical method to diagnose and prognose various diseases.


Choi J.,Langley High School | Choi J.,Luminescent | Kim Y.-T.,Clemson University | Lee J.H.,Luminescent
Analyst | Year: 2010

A novel competitive 1,1′-oxalyldiimidazole (ODI) chemiluminescent enzyme immunoassay (CLEIA) was developed as a method for rapid and simple screening of melamine in milk. Fat existing in milk acts as an inhibitor in the competitive binding interaction of melamine and anti-melamine in the presence of melamine-conjugated horseradish peroxidase. Thus, the calibration curve and sensitivity of competitive ODI CLEIA for the quantification of melamine in fat free milk were wider and better than those in milk containing fat. However, a centrifuge is not a good method for removing the inhibitor because a portion of the melamine is also removed with the fat. The incubation time (20 min) for the competitive binding interaction of anti-melamine and melamine in 20% milk diluted with PBS buffer of pH 7.4 was longer than that (10 min) in 100% milk even though the sensitivity of the former was better than latter. The limit of detection (1.12 ppb) determined in rapid ODI CLEIA (dynamic range: 3.8-125 ppb) for the quantification of melamine in 20% milk not containing fat was lower than those (6.3 and 9.0 ppb) calculated in relatively time-consuming luminol CLEIA and enzyme-linked immunosorbent assay (ELISA). Also, we expect that ODI-CLEIA (dynamic range: 62.5-2000 ppb) capable of directly quantifying melamine in 100% milk without any pretreatment can be applied as a new and simple method for rapid screening of melamine in milk. © 2010 The Royal Society of Chemistry.


Cho H.,Langley High School | Cho H.,Luminescent | Lee S.,Langley High School | Lee S.,Luminescent | Lee J.H.,Langley High School
Analyst | Year: 2012

The roles of CdS nanocrystals (quantum dots) stabilized by oleic acid ligands in toluene were investigated in the 1,1′-oxalyldiimidazole chemiluminescence (ODI-CL) reaction generated under various environmental conditions. CdS excited by high-energy intermediates formed in ODI-CL reaction emitted dim CL. Also, CdS acted as a catalyst to enhance the yield of high-energy intermediates, capable of transferring energy to fluorescent molecules, in aqueous ODI-CL reactions, whereas it acted as a strong quencher, capable of inhibiting the CL emission of excited fluorescent molecules, in non-aqueous ODI-CL reactions. Based on the role of CdS in the aqueous ODI-CL reaction, the limit of detection (LOD = signal/noise = 3, 0.1 μM) determined to quantify glucose using aqueous ODI-CL reaction in the presence of 2.75 μM CdS was four times lower than that in the absence of CdS. The range of recovery determined in the aqueous ODI-CL reaction in the presence of CdS was 91.7-104%. We expect that the aqueous ODI-CL reaction in the presence of CdS can be applied as a highly sensitive sensor in various research fields such as bioanalytical chemistry, environmental engineering, homeland security, and toxicology. This journal is © 2012 The Royal Society of Chemistry.


Son Y.,Pusan National University | Nam J.-S.,Pusan National University | Jang M.-K.,Pusan National University | Jung I.-A.,Langley High School | And 2 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2013

In this study, we evaluated the antiobesity effects of Vigna nakashimae (VN) extract and elucidated the underlying mechanisms. VN extract suppressed adipocyte differentiation and significantly attenuated the expression of adipogenic genes in 3T3-L1 cells. It decreased the expression of peroxisome proliferatoractivated receptor γ (PPARγ) and its target genes in fully differentiated 3T3-L1 cells. Moreover, it enhanced the phosphorylation of AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase (ACC), and increased the expression of fatty acid oxidation genes. In high-fat diet (HFD) fed mice, VN extract suppressed HFD-induced increases in body weight, epididymal fat tissue weight, and hepatic lipid levels, and decreased the plasma levels of triacylglycerols, fatty acid, total cholesterol, and inflammatory cytokines. Consistently with in vitro study results, VN extract prevented HFDinduced increases in the expression of PPARγ and its target genes, and restored the decrease in the phosphorylation of AMPK and ACC in epididymal fat and liver tissues. These findings suggest that Vigna nakashimae prevents obesity through suppression of PPARγ expression and activation of AMPK, and that it might be a useful dietary supplement for the prevention of obesity.


Nam J.S.,Pusan National University | Chung H.J.,Pusan National University | Jang M.K.,Pusan National University | Jung I.A.,Langley High School | And 3 more authors.
Nutrition Research and Practice | Year: 2013

Leaf of Sasa borealis, a species of bamboo, has been reported to exhibit anti-hyperglycemic effect. However, its antidiabetic mechanism is not fully understood. In this study, we examined whether an extract of S. borealis activates AMP-activated protein kinase (AMPK) and exerts anti-hyperglycemic effects. Treatment with the S. borealis extract increased insulin signaling and phosphorylation of AMPK and stimulated the expression of its downstream targets, including PPARa, ACO, and CPT-1 in C2C12 cells and PPARa in HepG2 cells. However, inhibition of AMPK activation attenuated insulin signaling and prevented the stimulation of AMPK target genes. The S. borealis extract increased glucose uptake in C2C12 cells and suppressed expression of the gluconeogenic gene, PEPCK in HepG2 cells. The extract significantly reduced blood glucose and triglyceride levels in STZ-induced diabetic mice. The extract enhanced AMPK phosphorylation and increased Glut-4 expression in the skeletal muscle of the mice. These findings demonstrated that the S. borealis extract exerts its anti-hyperglycemic effect through activation of AMPK and enhancement of insulin signaling. © 2013 The Korean Nutrition Society and the Korean Society of Community Nutrition.


Spassova M.A.,U.S. Environmental Protection Agency | Miller D.J.,U.S. National Institutes of Health | Nikolov A.S.,Langley High School
Oxidative Medicine and Cellular Longevity | Year: 2015

We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO 3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO 3 -caused oxidative damage. Our modeling revealed that sustained exposure to KBrO 3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemical's toxicity dose dependence based on the dose-response of early genotoxic events. © 2015 Maria A. Spassova et al.


PubMed | U.S. Environmental Protection Agency, Langley High School and U.S. National Institutes of Health
Type: | Journal: Oxidative medicine and cellular longevity | Year: 2015

We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO3-caused oxidative damage. Our modeling revealed that sustained exposure to KBrO3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemicals toxicity dose dependence based on the dose-response of early genotoxic events.


PubMed | Langley High School
Type: Journal Article | Journal: The Analyst | Year: 2012

The roles of CdS nanocrystals (quantum dots) stabilized by oleic acid ligands in toluene were investigated in the 1,1-oxalyldiimidazole chemiluminescence (ODI-CL) reaction generated under various environmental conditions. CdS excited by high-energy intermediates formed in ODI-CL reaction emitted dim CL. Also, CdS acted as a catalyst to enhance the yield of high-energy intermediates, capable of transferring energy to fluorescent molecules, in aqueous ODI-CL reactions, whereas it acted as a strong quencher, capable of inhibiting the CL emission of excited fluorescent molecules, in non-aqueous ODI-CL reactions. Based on the role of CdS in the aqueous ODI-CL reaction, the limit of detection (LOD = signal/noise = 3, 0.1 M) determined to quantify glucose using aqueous ODI-CL reaction in the presence of 2.75 M CdS was four times lower than that in the absence of CdS. The range of recovery determined in the aqueous ODI-CL reaction in the presence of CdS was 91.7-104%. We expect that the aqueous ODI-CL reaction in the presence of CdS can be applied as a highly sensitive sensor in various research fields such as bioanalytical chemistry, environmental engineering, homeland security, and toxicology.

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