Learning to Understand by Evolving Theories

In this paper, we describe an approach that enables an autonomous system to infer the semantics of a command (i.e. a symbol sequence representing an action) in terms of the relations between changes in the observations and the action instances. We present a method of how to induce a theory (i.e. a semantic description) of the meaning of a command in terms of a minimal set of background knowledge. The only thing we have is a sequence of observations from which we extract what kinds of effects were caused by performing the command. This way, we yield a description of the semantics of the action and, hence, a definition.Comment: KRR Workshop at ICLP 201

Momentum Investing: The Case of High-Tech IPOs

We document significant momentum effects in the high-tech IPO aftermarket beyond the initial (underpricing) run-up. Cumulative market-adjusted returns (CMARs) reveal a striking pattern. A local peak of just over 10 percent is reached around 20 trading days post-IPO coinciding with the expiry of the “quiet period”. A global peak (of about 33 percent) is reached after 105 trading days. The CMAR decays fairly rapidly thereafter possibly in anticipation of the expiry of the six-month lockup period. Further, we find strong evidence of a linkage between technical ex-ante observable variables and the momentum build-up. We conjecture that visceral factors may at least partially underlie the investor behavior that gives rise to the bubble-like CMAR pattern

Design of Rectenna using RF Harvesting for Batteryless IoT Sensors

In this paper, we propose a compact and highly efficient Rectenna design (rectifying antenna), operating on ISM band with the centre frequency of 2.4 GHz. A RF to DC conversion through Schottky diode (HSMS2860) is used to generate the dc voltage to operate a battery-less IoT Sensor for RF power harvesting using the designed Rectenna. We have achieved more than 80% efficiency through Advanced Design System (ADS-2016) simulation software at different power densities. Further a rectenna circuit is designed using RF to DC Schottky detector diode and a microstrip patch antenna. The rectenna circuit design is simulated through ADS 2016 simulation software. The Battery less sensor requires 2V- 2.5V dc voltage to perform an optimum performance. As per simulation and theoretical/practical modeling we have achieved more than 80% efficiency at single Schottky diode and its operating from 915 MHz to 5.8 GHz. Rectenna operates at lower power densities start from 0.4uW/cm. The proposed rectenna design is a possible candidate to be used as sensors/devices at frequency of 2.4GHz with current technologies e.g. ZigBee, Wi-Fi, BLE etc and future probable application could be long range radio sensor using the latest new generation LoRa technology its line of sight range between 10km-20km

Hysteroscopy: a boon in abnormal uterine bleeding

Background: Aim of the study was to analyze retrospectively the efficacy of hysteroscopy in the diagnosis of abnormal uterine bleeding (AUB).Methods: Eighty-six women in the reproductive and perimenopausal age group (20-50 years) visiting the gynaecology OPD from March 2018 to February 2019 with the complaints of abnormal uterine bleeding were enrolled in the study. All the patients who underwent hysteroscopic examination were subjected to endometrial curettage; which was sent for histopathological examination (HPE). The hysteroscopic findings were then corelated and compared with HPE.Results: Mean age of the patients was 37.2 years. Around 60.46% patients presented within six months of complaints. Clinically, 54.65% were diagnosed as menorrhagia, 37.2% as polymenorrhoea and 8.13% as intermenstrual bleeding. On hysteroscopy, 44.1% showed abnormal pathology. The positive findings including polyps (8.13%), calcification (3.48%), submucous myoma (12.79%), necrotic mass and forgotten IUCD (2.32%) and adhesions in one case. On the other hand, the findings of histopathology; 56 patients (65.11%) had normal / proliferative / atrophic endometrium, 17 (19.76%) had hyperplasia, 10 (11.62%) had polyps and 3 (3.48%) had calcified endometrium. There was no significant difference between two modalities for normal / proliferative / atrophic endometrium. The HPE diagnosed slightly higher patients of hyperplasia as compared to hysteroscopy. Hysteroscopy diagnosed a higher number of patients with submucous myoma and necrotic mass.Conclusions: Hysteroscopy provided additional visual information for some pathologies which otherwise would remain undiagnosed by HPE

The case for market inefficiency: investment style and market pricing

The level of informational efficiency of security markets has been a contentious issue among the academic and broader community over the last 35 years. This study highlights the growth in popularity in investment styles over this period, where investment decisions are made with only limited reference to available information and no concern with fair value (eg momentum investors and index investors). This paper models the market behaviour of fundamental, momentum and index investors and then simulates the behaviour of security prices in a market composed of investors following these three styles. Evidence is found to suggest that compositions of investment styles that are fairly typical of the mix of investors in current-day markets will lead to anomalous price behaviour similar to that found by other writers: an underreaction to new information which often gives rise to a subsequent overreactio

Comparative evaluation of Nano-Hydroxyapatite preparation and Calcium Sucrose Phosphate on microhardness of deciduous teeth after iron drop exposure - An in-vitro study

To evaluate and compare the microhardness of deciduous teeth treated with nano-hydroxyapatite and calcium sucrose phosphate after iron drop exposure. Twenty healthy anterior deciduous teeth were collected and stored in 0.9% saline solution at room temperature. All the teeth were immersed in artificial saliva in an incubator shaker at 37° for an hour and then subjected to Vickers microhardness test at 100g load for 5 seconds. The teeth were then immersed in iron drop for 5 minutes, twice daily, rinsed with distilled water and kept in artificial saliva. This procedure was repeated for 7 days and teeth were subjected to microhardness testing. Further, the teeth were divided in two groups, each group containing 10 teeth. In group I, nanohydroxyapatite preparation and in group II, calcium sucrose phosphate were applied for 10 minutes, twice daily for 7 days and subjected again to microhardness testing again. Vickers microhardness analysis revealed that iron drop exposure to teeth caused significant decrease in microhardness (p<0.05). Application of nanohydroxyapatite preparation in Group I showed significantly increased enamel microhardness (206.90) than that after iron drop exposure. Similarly, application of calcium sucrose phosphate in Group II showed significantly increased enamel microhardness (200.89) than that after iron drop exposure. Statistical difference was seen between the two groups, with nanohydroxyapatite preparation showing increased microhardness than calcium sucrose phosphate. Nanohydroxyapatite preparation and calcium sucrose phosphate have remineralizing effect over teeth affected by acid challenge of iron drops, nanohydroxyapatite preparation showing better results than calcium sucrose phosphate

Cardiovascular disease risk: it is complicated, but race and ethnicity are key, a Bayesian network analysis

BackgroundCardiovascular diseases are the leading cause of morbidity and mortality in the United States. Despite the complexity of cardiovascular disease etiology, we do not fully comprehend the interactions between non-modifiable factors (e.g., age, sex, and race) and modifiable risk factors (e.g., health behaviors and occupational exposures).ObjectiveWe examined proximal and distal drivers of cardiovascular disease and elucidated the interactions between modifiable and non-modifiable risk factors.MethodsWe used a machine learning approach on four cohorts (2005–2012) of the National Health and Nutrition Examination Survey data to examine the effects of risk factors on cardiovascular risk quantified by the Framingham Risk Score (FRS) and the Pooled Cohort Equations (PCE). We estimated a network of risk factors, computed their strength centrality, closeness, and betweenness centrality, and computed a Bayesian network embodied in a directed acyclic graph.ResultsIn addition to traditional factors such as body mass index and physical activity, race and ethnicity and exposure to heavy metals are the most adjacent drivers of PCE. In addition to the factors directly affecting PCE, sleep complaints had an immediate adverse effect on FRS. Exposure to heavy metals is the link between race and ethnicity and FRS.ConclusionHeavy metal exposures and race/ethnicity have similar proximal effects on cardiovascular disease risk as traditional clinical and lifestyle risk factors, such as physical activity and body mass. Our findings support the inclusion of diverse racial and ethnic groups in all cardiovascular research and the consideration of the social environment in clinical decision-making