953 research outputs found
Film Review: Yoo Hoo, Mrs. Goldberg
No full textThe author presents a review of the documentary Yoo Hoo, Mrs. Goldberg
Data for "Prediction of Phakic Intraocular Lens Vault Using Machine Learning of Anterior Segment Optical Coherence Tomography Metrics"
No full textPrediction of Phakic Intraocular Lens Vault Using Machine Learning of Anterior Segment Optical Coherence Tomography Metrics.
Authors: Kazutaka Kamiya, MD, PhD1, Ik Hee Ryu, MD, MS2, Tae Keun Yoo, MD2, Jung Sub Kim MD2, In Sik Lee, MD, PhD2, Jin Kook Kim MD2, Wakako Ando CO3, Nobuyuki Shoji, MD, PhD3, Tomofusa, Yamauchi, MD, PhD4, Hitoshi Tabuchi, MD, PhD4.
Author Affiliation: 1Visual Physiology, School of Allied Health Sciences, Kitasato University, Kanagawa, Japan, 2B&VIIT Eye Center, Seoul, Korea, 3Department of Ophthalmology, School of Medicine, Kitasato University, Kanagawa, Japan, 4Department of Ophthalmology, Tsukazaki Hospital, Hyogo, Japan.
We hypothesize that machine learning of preoperative biometric data obtained by the As-OCT may be clinically beneficial for predicting the actual ICL vault. Therefore, we built the machine learning model using Random Forest to predict ICL vault after surgery.
This multicenter study comprised one thousand seven hundred forty-five eyes of 1745 consecutive patients (656 men and 1089 women), who underwent EVO ICL implantation (V4c and V5 Visian ICL with KS-AquaPORT) for the correction of moderate to high myopia and myopic astigmatism, and who completed at least a 1-month follow-up, at Kitasato University Hospital (Kanagawa, Japan), or at B&VIIT Eye Center (Seoul, Korea).
This data file (RFR_model(feature=12).mat) is the final trained random forest model for MATLAB 2020a.
Python version:
***************************************************************
from sklearn.model_selection import train_test_split
import pandas as pd
import numpy as np
from sklearn.ensemble import RandomForestClassifier
from sklearn.ensemble import RandomForestRegressor
# connect data in your google drive
from google.colab import auth
auth.authenticate_user()
from google.colab import drive
drive.mount('/content/gdrive')
# Change the path for the custom data
# In this case, we used ICL vault prediction using preop measurement
dataset = pd.read_csv('gdrive/My Drive/ICL/data_icl.csv')
dataset.head()
#optimal features (sorted by importance) :
# 1. ICL size 2. ICL power 3. LV 4. CLR 5. ACD 6. ATA
# 7. MSE 8.Age 9. Pupil size 10. WTW 11. CCT 12. ACW
y = dataset['Vault_1M']
X = dataset.drop(['Vault_1M'], axis = 1)
# Split the dataset to train and test data
# For a simple validation test, we split data to 8:2
train_X, test_X, train_y, test_y = train_test_split(X, y, test_size=0.2, random_state=0)
# Optimal parameter search could be performed in this section
parameters = {'bootstrap': True,
'min_samples_leaf': 3,
'n_estimators': 500,
'criterion': 'mae'
'min_samples_split': 10,
'max_features': 'sqrt',
'max_depth': 6,
'max_leaf_nodes': None}
RF_model = RandomForestRegressor(**parameters)
RF_model.fit(train_X, train_y)
RF_predictions = RF_model.predict(test_X)
importance = RF_model.feature_importances
Young Investigator: Michelle J Yoo
No full text Supervisor’s supporting comments I have always been impressed with Michelle’s ability to conduct research in an independent and yet highly effective manner. Part of her research in my group has examined the use of affinity columns to examine drug–protein binding with serum proteins, such as human serum albumin. This work is extremely important to the fields of pharmaceutical chemistry and clinical chemistry in providing the data needed for the development of new drugs or in the optimization of treatments for patients with new, or existing, drugs. Another topic that Michelle has examined in her research is the use of new supports based on monolithic materials and ultrafast-extraction methods for affinity-based separations of biological samples and high-throughput screening of drug–protein binding. She was the lead author on a review written on this topic and also has several research publications related to this area of work. During her graduate studies, Michelle has emerged as a real leader in my group. She has excellent people and communication skills and is highly motivated in her pursuit of an advanced degree in analytical chemistry and bioanalysis. I have extremely high expectations for her in the future as she continues her career. Nominated by: David S Hage, University of Nebraska, Department of Chemistry, Hamilton Hall 704, Lincoln, NE 68588, USA </jats:p
Accessing and using multilanguage information by users searching in differenct information retrieval systems
No full textThere is an underlying assumption in the exchange of scholarly information that knowledge will be transferred across country borders, cultures, and languages. It is this sharing of scholarly information is considered an essential pre-requisite necessary for the advancement of knowledge. Nonetheless, in the current English dominant environment of information retrieval (IR) systems, there are numerous obstacles confronting users who seek to access and use non-English information.
The purposes of this study are: to explore the information behaviors of those seeking non-English information; to identify difficulties of individuals' experiences when accessing and using non-English information in current IR systems; to develop an explanatory model determining how person characteristics, experiential knowledge, and situation factors influence search behaviors and evaluations of bibliographic information.
Two separate studies are conducted to explore the above issues: an online questionnaire of users of multilanguage information retrieval systems; and an experiment with individuals accessing information on different topics using different languages and systems. The participants in these studies include academic researchers and library personnel and are individuals who regularly interact with Chinese, Japanese, Korean and English records via IR systems.
The survey and experiment participants note the lack of non-English access via indexing terms, the lack of non-English records in major online databases which index journals, the lack of English translation of abstracts, and the lack of coherent and understandable access to non-Roman language materials. The users of non-English information expect to have a system with cross language information retrieval functions providing clear access to full text non-English information. Importantly, having understandable bibliographic records are essential when individuals make decisions on their expected use of non-English documents.
The experiment data analyses reveal there are different IR system search behaviors by subjects' with different language backgrounds, professions, language knowledge, topic knowledge and its target language, especially comparing English with non-English searches. An explanatory model for non-English searching model was built based on various statistical analyses of experiment data. The model depicts the importance of statistically significant relationships among person characteristics and experiential knowledge which explain search behaviors and intention to use retrieved information when individuals seek non-English/non-Roman alphabet information.Ph.D.Includes bibliographical references (p. 226-238)by Yoo Jin H
Kochosa sharae Framenau & Castanheira & Yoo 2023, sp. nov.
No full textKochosa sharae sp. nov. (Figs 20, 22A–E) Holotype. Male, Flinders Chase National Park, 4 km W Rocky River Headquarters, Kangaroo Island (35º 57'00''S 136º42'30''E, South Australia, AUSTRALIA), E. G. Matthews, J. A. Forrest, 1–7 November 1990 (SAM NN13502). Etymology. The specific epithet is a matronym honouring a good friend of the senior author, Shar Ramamurthy, currently Senior Manager, Environmental Water at the Department of Environment, Land, Water and Planning (Victoria), for her support during the mutual times at Melbourne University. Other material examined. Australia: South Australia: 2 males, Snug Cove, 9 km NNE, Kangaroo Island, 35º47'19''S 136º48'59''E (NN13503–4). Diagnosis. Male pedipalp morphology of K. sharae sp. nov. is similar to that of K. fleurae sp. nov., both sharing a digitiform basoembolic apophysis; however, it is comparatively smaller and more curved in K. sharae sp. nov. (Fig. 22E). Description. Male (based on holotype, SAM NN13502). Cephalothorax. Dorsally dark brown; broad median light band narrowing posteriorly; lateral light bands distinct; white setae throughout (Fig. 22A). Sternum dark brown with few white setae (Fig. 22B). Abdomen. Dorsally dark olive brown; cardiac mark continuous, narrowest posteriorly and there bordered by black spots (Fig. 22A). Venter light olive-brown, anteriorly somewhat darker (Fig. 22B). Pedipalps (Figs 22C–E). Patella of distinct light brown colouration with white setae; tegular apophysis round lobe, almost translucent; basoembolic apophysis digitiform and curved; embolus straight medially, curved basally and then apically. (Fig. 22E) Legs. Brown with darker annulations; spination of leg I: femur. 2 dorsum, 1 apicodorsal, 1 apicoprolateral, 1 apicoretrolateral (very small); tibia. 3 ventral pairs, 2 prolateral, 2 retrolateral; metatarsus. 3 ventral pairs, 1 apicoventral, 2 prolateral, 1 apicoprolateral, 2 retrolateral, 1 apicoretrolateral. Measurements: TL 4.84, CL 2.67, CW 1.99. Eyes: AME 0.10, ALE 0.10, PME 0.24, PLE 0.23. Row of eyes: AE 0.64, PME 0.76, PLE 0.96. Sternum (length/width) 1.21/0.99. Labium (length/width) 0.36/0.38. AL 2.17, AW 1.49. Legs: Length of segments: Pedipalp 1.00+0.91+-+0.81=2.72, I 1.80+2.01+1.44+0.96=6.21; II 1.68+2.04+1.4 6+0.96=6.14, III 1.68+1.84+1.56+0.91=5.99; IV 2.06+2.32+2.30+1.24=7.92. Variation. Size (range, mean ± s.d.): TL 4.60–4.84, 4.75 ± 0.13; CL 2.65–2.72, 2.68 ± 0.04; CW 1.85–1.99, 1.91 ± 0.07, n = 3. One of the males was much darker than the one illustrated here and with less distinct median carapace band and abdominal cardiac mark. Female. Unknown. Life history and habitat preferences. There is no information on the habitat of this species; the three males of K. sharae sp. nov. were found between October to November suggesting this to be a spring-mature species. Distribution. Kochosa sharae sp. nov. is only known from western Kangaroo Island, South Australia (Fig. 20).Published as part of Framenau, Volker W., Castanheira, Pedro De S. & Yoo, Jung-Sun, 2023, The artoriine wolf spiders of Australia: the new genus Kochosa and a key to genera (Araneae: Lycosidae), pp. 301-357 in Zootaxa 5239 (3) on page 338, DOI: 10.11646/zootaxa.5239.3.1, http://zenodo.org/record/763479
Kochosa tongiorgii Framenau & Castanheira & Yoo 2023, sp. nov.
No full textKochosa tongiorgii sp. nov. (Figs 27, 30A–E) Holotype. 1 male, Davies Creek National Park (17º00'S 145º34'E, Queensland, AUSTRLIA), 26 November 1992 – 15 April 1993, R. J. & S. Raven, P. & E. Lawless (QM S83707). Etymology. The specific epithet is a patronym for the late Paolo Tongiorgi (1936–2018) for his contribution to wolf spider taxonomy. The senior author has fond memories of Paolo’s support during his work on Arctosa cinerea Fabricius, 1777 (e.g., Framenau 1995). Other material examined. 4 males, 1 juvenile, same data as holotype (QM S19781). Diagnosis. Males of K. tongiorgii sp. nov. differ from all other species within the genus by the unique colouration of the carapace; dense white setae cover it almost entirely except for the flanks of the cephalic area (Fig. 30A). The long and tapering embolus is opposed by a sclerotised, digitiform process originating at the retrolateral edge of the apical division, unique within the genus (Fig. 30E). The female of K. tongiorgii sp. nov. is unknown. Description Male (based on holotype, QM S83707). Cephalothorax. Dorsally dark brown, covered almost entirely (except cephalic flanks) by white, short and stout setae (Fig. 30A). Sternum brown (Fig. 30B). Abdomen. Dorsally dark brown with continuous cardiac mark, dense cover of white shot and stout setae obscure colouration as on carapace (Fig. 30A). Venter olive-grey, centrally somewhat lighter (Fig. 30B). Pedipalps (Fig. 30C–E). Embolic base exposed; tegular apophysis broadly subtriangular; embolus narrow and long; apical part of embolus supported by trough-shaped structure; sclerotised process opposing embolus. Legs. Brown, femora darkest; spination of leg I: femur: 3 dorsal; tibia: 3 ventral pairs and 1 apicoventral; metatarsus: 4 ventral pairs, 1 prolateral, 1 apicoprolateral. Measurements. TL 3.46, CL 1.93, CW 1.25. Eyes: AME 0.07, ALE 0.06, PME 0.17, PLE 0.17. Row of eyes: AE 0.47, PME 0.63, PLE 0.70. Sternum (length/width) 0.81/0.72. Labium (length/width) 0.24/0.28. AL 1.62, AW 0.94. Legs: Length of segments: Pedipalp 0.71+0.67+-+0.64=2.02, I 1.21+1.60+1.03+0.74=4.58; II 1.21+1.49+1.0 3+0.71=4.44, III 1.10+1.28+1.14+0.64=4.16; IV 1.67+1.92+1.82+0.89=6.30. Variation. Size (range, mean ± s.d.): TL 3.46–3.71, 3.57 ± 0.15; CL 1.93–2.20, 2.06 ± 0.10; CW 1.25–1.40, 1.30 ± 0.06, n = 5. There was not major difference in colour pattern in any of the males, although the abdomen was somewhat lighter in one specimen. Female. Unknown. Life history and habitat preferences. Unknown. Distribution. Kochosa tongiorgii sp. nov. is only know from the type locality, Davies Creek National Park, north-eastern Queensland (Fig. 27).Published as part of Framenau, Volker W., Castanheira, Pedro De S. & Yoo, Jung-Sun, 2023, The artoriine wolf spiders of Australia: the new genus Kochosa and a key to genera (Araneae: Lycosidae), pp. 301-357 in Zootaxa 5239 (3) on page 350, DOI: 10.11646/zootaxa.5239.3.1, http://zenodo.org/record/763479
Kochosa fleurae Framenau & Castanheira & Yoo 2023, sp. nov.
No full textKochosa fleurae sp. nov. (Figs 13, 14A–E) Holotype. Male, Skylark Road, Whipstick (36º37'30''S 144º16'00″E, Victoria, AUSTRALIA), J. Shield, 10–17 December 1998, Whipstick Forest Survey MS # 138 (MV K-8672). Etymology. The specific epithet is a matronym for a very good friend of the senior author, Fleur de Crespigny (currently Head, Dementia Unit at the Australian Institute of Health and Welfare, Canberra). Other material examined. 2 males, Skylark Road, Whipstick, 36º37'30''S 144º16'00″E (MV K-7728). Diagnosis. Males of K. fleurae sp. nov. are separated from those of all other species of the genus by their unique long and sharp basoembolic apophyses and flat and broad embolus (Fig. 14E). They are most similar to K. asterix sp. nov. but differ from those due to the ventrally folded basoembolic apophysis (Fig. 14E). The female of K. fleurae sp. nov. is unknown. Description. Male (based on holotype, MV K-8672). Cephalothorax. Dorsally dark brown; median light band slightly narrowing posteriorly, covered with white setae; lateral light bands broad and covered with white setae (Fig. 14A). Sternum dark brown (Fig. 14B). Abdomen. Dorsally light olive grey; cardiac mark continuous bordered by indistinct dark brown discolourations in posterior half (Fig. 14A). Venter brown (Fig. 14B). Pedipalps (Fig. 14C–E). Embolus broad and flat and tapering to apex; basoembolic apophysis distinct, long and pointing retrolaterally; tegular apophysis forms a small round lobe situated apically on tegulum. Legs. Light brown with irregular darker discolourations; spination of leg I: femur: 4 dorsal, 2 retrolateral (very small); tibia: 4 ventral pairs (apical pair small), 2 prolateral, 1 retrolateral; metatarsus: 4 ventral pairs (apical pair small and closer), 2 prolateral; 1 apicoprolateral, 1 retrolateral. Measurements. TL 4.39, CL 2.49, CW 1.64. Eyes: AME 0.10, ALE 0.10, PME 0.31, PLE 0.30. Row of eyes: AE 0.48, PME 0.65, PLE 0.79. Sternum (length/width) 0.99/0.92. Labium (length/width) 0.28/0.34. AL 1.99, AW 1.35. Legs: Length of segments: Pedipalp 0.84+0.28+0.36+0.88 = 2.36, I 1.42+1.83+1.17+0.85=5.27; II 1.42+1.78 +1.17+0.89=5.26, III 1.35+1.49+1.24+0.74=4.82; IV 1.85+2.24+2.14+1.07=7.30. Variation. Size (range, mean ± s.d.): TL 4.39 – 5.82, 4.93 ± 0.75; CL 2.49 – 3.18, 2.78 ± 0.35; CW 1.64–1.91, 1.75 ± 0.14, n = 3. Both other males are of similar colouration as the holotype. Female. Unknown. Life history and habitat preferences. The three males of K. fleurae sp. nov. were found in Whipstick Westringia (Westringia crassifolia) shrub and forest between October and December. Westringia crassifolia is listed as Endangered in Victoria and Australia and this conservation rating may also be applied to K. fleurae sp. nov. if the species is a habitat specialist relying on this species. Distribution. Only known from and around the type locality, Whipstick (Victoria) (Fig. 13).Published as part of Framenau, Volker W., Castanheira, Pedro De S. & Yoo, Jung-Sun, 2023, The artoriine wolf spiders of Australia: the new genus Kochosa and a key to genera (Araneae: Lycosidae), pp. 301-357 in Zootaxa 5239 (3) on pages 325-326, DOI: 10.11646/zootaxa.5239.3.1, http://zenodo.org/record/763479
Mechanisms of greater cardiomyocytes functions on conductive nanoengineered composites for cardiovascular applications. [Corrigendum]
No full textStout DA, Yoo J, Noemi Santiago-Miranda AN, Webster TJ International Journal of Nanomedicine 2012,7:5653&ndash;5669An author was incorrectly listed as Noemi Santiago-Miranda A, but should be listed as:Santiago-Miranda AN.In addition, the correct spelling for Santiago-Miranda AN institution affiliation is Mayag&uuml;ez instead of Mayag&uuml;es.Read the original articl
Kochosa timwintoni Framenau & Castanheira & Yoo 2023, sp. nov.
No full textKochosa timwintoni sp. nov. (Figs 27, 28A–E, 29A–D) Holotype. Male, West Mt Barren (34º13'S 119º26'E, Western Australia, AUSTRALIA), R. J. McKay, 15 July 1970, on sand (WAM T86692). Etymology. The specific epithet is a patronym honouring the Western Australian author Tim Winton for his ongoing environmental advocacy (i.e., Winton 2008). His novels have given the senior author hours of pleasure and time of reflection. Other material examined (4 males, 6 females). Australia. Western Australia: 1 male, West Mt Barren, 34º13'S 119º26'E (WAM 71 /499); 2 females, same locality (WAM 71 /856–7); 1 female (WAM 70 /209), same locality; 2 males, same locality (WAM T86693); 3 females, same locality (WAM70 /246a–c). Diagnosis. Males of K. timwintoni sp. nov. can be easily separated from other species of Kochosa gen. nov. by the unique light brown to yellow, broad base of the embolus (Fig. 28C, E). They are most similar to those of K. westralia sp. nov., but in addition to the embolus, the first species has a triangular and pointing retrolaterally basoembolic apophysis, whereas it is broad and round in K. westralia sp. nov. (Figs 28E vs 31E). The epigyne of female K. timwintoni sp. nov. has a distinct median septum similar to K. obelix sp. nov. and K. westralia sp. nov., but the posterior transverse part is much broader, so that the median septum forms and inverted “T” (Figs 29C vs 19D, 32C). Description. Male (based on holotype, WAM T86692). Cephalothorax. Dorsally dark brown; indistinctly lighter medially (Fig. 28A); broad lateral bands with white setae (Fig. 28A); Sternum dark shiny brown (Fig. 28B). Abdomen. Dorsally dark olive-grey; cardiac mark continuous, but almost dissolved into two spots (Fig. 28A). Venter uniformly olive-grey (Fig. 28B). Pedipalps (Figs 28C–E). Cymbium comparatively broad; embolic division almost entirely exposed; tegular apophysis reduced, shark-tooth-shaped; basoembolic apophysis somewhat duckbill-shaped, pointing retrolatrally (Fig. 28E); embolus with light brown base, apically stout. Legs. Dark brown, with light annulations; spination of leg I: femur: 3 dorsal (apical one small), 1 apicoprolateral; tibia: 3 ventral pairs, 1 prolateral; metatarsus: 3 ventral pairs, 1 apicoventral, 2 prolateral, 1 apicoprolateral, 1 retrolateral, 1 apicoretrolateral. Measurements. TL 3.91, CL 2.34, CW 1.64. Eyes: AME 0.09, ALE 0.08, PME 0.26, PLE 0.21. Row of eyes: AE 0.47, PME 0.70, PLE 0.86. Sternum (length/width) 0.98/0.86. Labium (length/width) 0.19/0.30. AL 1.72, AW 1.56. Legs: Length of segments (femur + patella/tibia + metatarsus + tarsus = total length): Pedipalp 0.81+0.56+- +0.81=2.19, I 1.53+1.63+1.28+0.86=5.30; II 1.35+1.72+1.40+0.81=5.28, III 1.40+1.63+1.21+0.70=4.93; IV 1.93 +2.12+2.02+0.91=6.98. Variation. Size (range, mean ± s.d.): TL 3.91–4.40, 4.07 ± 0.22; CL 2.30–2.70, 2.44 ± 0.18; CW 1.64–2.00, 1.81 ± 0.15, n = 4. There is little colour variation between the males examined here except for somewhat lighter legs in one specimen. Female (based on WAM 70/246a; epigyne dorsal WAM 70/246b). Cephalothorax and abdomen. Colouration and setae-arrangement generally as male, but light median and lateral carapace bands less distinct (Fig. 29A, B). Epigyne (Fig. 29C, D). Ventral view: median septum inverted T-shaped (Fig. 29C); dorsal view (based on WAM 70/246b): spermathecal heads spherical, comparatively large, spermathecal stalks basally curved (Fig. 29D). Legs. Light brown with dark annulations; spination of leg I: femur: 3 dorsal; tibia: 3 ventral pairs, 1 prolateral; metatarsus: 3 ventral pairs and 1 apicoventral, 2 prolateral; 1 apicoprolateral; 1 retrolateral; 1 apicoretrolateral. Measurements. TL 5.50, CL 2.55, CW 1.70. Eyes:AME 0.11, ALE 0.09, PME 0.25, PLE 0.23. Row of eyes: AE 0.67, PME 0.85, PLE 1.16. Sternum (length/width) 1.00/0.90. Labium (length/width) 0.40/0.47. AL 2.60, AW 2.30. Pedipalp 0.75+0.77+-+0.75=2.27, I 1.61+1.75+1.10+0.65=5.10, II 1.45+1.66+1.05+0.65=4.81, III 1.25+1.71+1.26 +0.65=4.76, IV 2.05+2.01+2.01+0.75=6.82. Variation. Size (range, mean ± s.d.): TL 5.32–5.62, 5.46 ± 0.13; CL 2.50–2.55, 2.50 ± 0.08; CW 1.70–1.95, 1.81 ± 0.10, n = 4. The females of K. timwintoni sp. nov. are generally poorly preserved and it is therefore difficult to assess any colour variation. Life history and habitat preferences. Males and females of K. timwintoni sp. nov. were found in July and August suggesting reproductive activity in winter. The habitat preferences appear unusual, as specimens were found “on sand” or “on sand plain”, in contrast to most other species of Kochosa gen. nov. which appear to prefer forests or woodland. Distribution. Only know from the type locality, West Mt Barren, Western Australia (Fig. 27).Published as part of Framenau, Volker W., Castanheira, Pedro De S. & Yoo, Jung-Sun, 2023, The artoriine wolf spiders of Australia: the new genus Kochosa and a key to genera (Araneae: Lycosidae), pp. 301-357 in Zootaxa 5239 (3) on pages 347-350, DOI: 10.11646/zootaxa.5239.3.1, http://zenodo.org/record/763479
A Service of zbw Leibniz-Informationszentrum Wirtschaft Leibniz Information Centre for Economics -Attribution 4.0 International (CC BY 4.0) Reexamining the Schmalensee effect
No full textStandard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in Reexamining the Schmalensee effect Jeong-Yoo Kim Abstract The author reexamines the Schmalensee effect from a dynamic perspective. Schmalsensee's argument suggesting that high quality can be signaled by high prices is based on the assumption that higher quality necessarily incurs higher production cost. In this paper, the author argues that firms producing high-quality products have a stronger incentive to lower the marginal cost of production cost because they can then sell larger quantities than low-quality firms can. If this dynamic effect is large enough, then the Schmalensee effect degenerates and, thus, low prices signal high quality. This result is different from the Nelson effect relying on the assumption that only the high-quality product can generate repeat purchase, because the result is valid even if low-quality products can also be purchased repeatedly. The author characterizes a separating equilibrium in which a highquality monopolist invests more to reduce cost and, as a result, charges a lower price. Separation is possible due to a difference in quantities sold in the second period across qualities. JEL D82 L1
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